JP2007171576A - Substantially non-photosensitive black and white monosheet thermographic recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substantially non-photosensitive black and white monosheet thermographic recording material excellent in silver tone and raw stock preservability, low in fog and excellent also in image preservability under photoirradiation even when the recording material is rapidly processed with a small thermal printer or a diagnosis is made using a high-illuminance X-ray film viewer. <P>SOLUTION: The substantially non-photosensitive black and white monosheet thermographic recording material has an image forming layer containing an organic silver salt, a binder and a reducing agent on a support, wherein the image forming layer contains a leuco dye which develops a color in heat development to form a dye image. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a substantially non-photosensitive black and white monosheet thermographic recording material.

  In recent years, dry processing using photothermographic materials or non-photosensitive thermographic materials has become the mainstream in the field of image formation in place of wet development processing. In particular, dry processing using a non-photosensitive thermographic material is widely used for small heat development processing.

  In thermographic materials, the thermographic imaging process relies on the use of heat to aid in image formation. Typically, the heat sensitive imaging layer is coated on top of a suitable substrate or support such as paper, plastic, metal, glass or the like. The resulting thermographic composition is typically heated to a high temperature of about 60-225 ° C. to form an image. Often the thermographic composition is contacted with a thermal head of a thermographic recording device such as a thermal printer, thermal facsimile or the like.

In such a case, a non-adhesive layer is coated on top of the image forming layer in order to prevent adhesion of the thermographic composition to the thermal head of the apparatus used. As for the image forming layer, thermophotographic materials based on silver salts of long chain fatty acids such as silver behenate are known. Silver behenate is reduced at a high temperature by a silver ion reducing agent such as hydroquinone, substituted hydroquinone, hindered phenol, catechol, pyrogal, methyl gallate, and leuco dye to form an image. It is also known to add other additives to the image forming layer of the thermographic composition to increase its efficiency. For example, US Pat. No. 2,910,377 discloses that the color and density of silver images for such materials can be improved by adding toner to the imaging layer. A toner that mainly increases image density is also called a development accelerator. U.S. Pat. No. 3,080,254 discloses the use of phthalazinone as a toner in thermal copy paper. U.S. Pat. No. 3,847,612 discloses the use of an imaging system combining imidazole and phthalic acid. Image formation can also be improved by combining phthalazine with phthalic acid and other organic acids. Such disclosed combinations are particularly valuable when relatively weak reducing agents such as hindered phenols are used as developers for silver soap. U.S. Pat. No. 4,585,734 discloses that a combination of phthalazine and an active hydrogen-containing heterocyclic compound (e.g., phthalimide, naphthalimide, pyrazole, succinimide, etc.) can be used in a dry silver image system to give a good tint. is doing. In recent years, the processing time has been accelerated, and since a high-illumination Schaukasten is used for mammo film at the time of diagnosis, there is an urgent need to develop technology for maintaining a neutral color tone even under such circumstances. Various attempts have been made to improve the color tone (Patent Documents 1 to 5), but sufficient performance as a film for rapid processing and mammo has not been obtained.
US Patent Application Publication No. 2005/0186521 US Patent Application Publication No. 2005/0186519 US Patent Application Publication No. 2005/0096788 US Patent Application Publication No. 2005/0137387 US Patent Application Publication No. 2005/0137388

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a silver-tone, raw storage even when a rapid thermal processing is performed by a small thermal printer or a diagnosis is performed using a high-illumination shakasten. It is to provide a substantially non-photosensitive black-and-white monosheet thermographic recording material having excellent properties, low fog, and excellent light irradiation image storage stability.

  The above object of the present invention can be achieved by the following constitution.

  1. It has an image forming layer containing an organic silver salt, a binder and a reducing agent on a support, and the image forming layer contains a leuco dye that forms a dye image by color development during heat development. A substantially non-photosensitive black and white monosheet thermographic recording material.

  2. 2. The substantially non-photosensitive black and white monosheet thermographic recording material according to 1, wherein at least one of the maximum absorption wavelengths of the dye image is in the range of 360 nm to 450 nm.

  3. 3. The substantially non-photosensitive black and white monosheet thermographic recording material according to 1 or 2, wherein at least one of the maximum absorption wavelengths of the dye image is in the range of 600 nm to 700 nm.

  4). 4. The substantially non-photosensitive black and white according to any one of 1 to 3, wherein the ratio of the addition amount of the leuco dye to the total of the reducing agents is 0.001 to 0.2 in terms of molar ratio. Monosheet thermographic recording material.

  5. 5. The substantially non-photosensitive black and white monosheet thermographic recording material according to any one of 1 to 4, which contains a compound represented by the following general formula (SF).

General formula (SF)
(R _f − (L ₁ ) _m1 −) _p − (Y) _n1 − (A) _q
[Wherein R _f represents a substituent containing a fluorine atom, L ₁ represents a divalent linking group having no fluorine atom, and Y represents a (p + q) -valent linking group having no fluorine atom. , A represents an anionic group or a salt thereof, m1 and n1 each represents an integer of 0 or 1, p represents an integer of 1 to 3, and q represents an integer of 1 to 3. However, when q is 1, m1 and n1 are not 0 at the same time. ]

  According to the present invention, even when performing rapid processing with a small thermal printer or performing diagnosis using a high-illumination Schaukasten, it is excellent in silver tone, raw storability, low fog, and light irradiation image storability. An excellent substantially non-photosensitive black and white monosheet thermographic recording material (hereinafter also referred to as a thermographic material or a thermophotographic material) can be provided.

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

  In the thermographic material according to the present invention, the structure defined in any one of claims 1 to 4 can be used in a silver color even when rapid thermal development is performed by a small thermal printer or diagnosis is performed using a high illuminance Schaukasten. It was possible to provide a thermographic material having excellent tone and raw storage, low fog and excellent image storage.

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

  As a result of studying various problems of the above-described prior art, the present inventors have conducted light irradiation at the time of using a high illuminance Schaukasten even if the stabilizers and coupler color formers described in Patent Documents 1 to 5 are used. We found that image preservation and color deterioration during rapid processing cannot be improved sufficiently. Thus, as a result of examining various technical means, it has been found that the problem of the present invention can be solved by using a leuco dye that develops a color image upon heat development to form a dye image.

(Image tone)
First, the color tone of an image obtained by thermally developing a thermographic material containing the leuco dye of the present invention will be described.

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

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

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

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

However, as a result of further intensive studies on the thermographic material of the present invention, the horizontal axis is u ^* or a ^* and the vertical axis is CIE 1976 (L ^* u ^* v ^* ) color space or (L ^* a ^* b ^* ) color space. When plotting u ^* , v * or a ^* , b ^* at various photographic densities on a graph with v ^* or b ^* and creating a linear regression line, the linear regression line is within a specific range. By adjusting, it was found that the diagnostic ability was equal to or better than that of conventional wet silver salt thermographic materials. A preferable range of conditions is described below.

(A) The silver images obtained after heat development processing of the thermographic material were measured for the optical densities of 0.5, 1.0, 1.5 and the lowest optical density, and CIE 1976 (L ^* u ^* v ^* ) The determination coefficient (multiple determination) R ^{2 of} the linear regression line created by arranging u ^* and v ^* at the above optical densities on a two-dimensional coordinate with the horizontal axis of the color space u ^* and the vertical axis v ^*. It is preferably 0.998 to 1.000. Furthermore, it is preferable that the v ^* value of the intersection with the vertical axis of the linear regression line is −5 to 5 and the slope (v ^* / u ^* ) is 0.7 to 2.5.

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

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

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

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

  Conventionally, phthalazinone or phthalazine and phthalic acids and phthalic anhydrides are generally used as toning agents. Examples of suitable toning agents are RD17029, U.S. Pat. Nos. 4,123,282, 3,994,732, 3,846,136, 4, No. 021,249 and the like.

  In the present invention, a rapid thermal processing is performed using a small thermal printer. However, there is a problem that the silver tone is greatly deviated from the neutral preferable color tone as compared with the normal processing. In order to solve these problems, the above-described conventional color-adjusting agents are insufficient, and a compound (leuco dye) that forms a dye image by developing color imagewise during heat development is required. . These compounds include leuco dyes that develop color during thermal development and form a dye image having a maximum absorption wavelength of 360 nm to 450 nm, or leuco dyes that develop color during thermal development and form a dye image having a maximum absorption wavelength of 600 nm to 700 nm. Dyes are preferred, but the case of containing both compounds is particularly preferred for obtaining a good silver tone. As these compounds, it is preferable to use leuco dyes described in detail below.

(Leuco dye)
As described above, the thermographic material of the present invention adjusts the color tone using a leuco dye. The leuco dye is preferably any colorless or slightly colored compound that is oxidized to a colored form when heated at a temperature of about 80 ° C. to 200 ° C. for about 0.5 seconds to 30 seconds. Any leuco dye that forms a pigment by oxidation with an oxidant or the like can be used. Compounds that are pH sensitive and can be oxidized to a colored state are useful.

  Representative leuco dyes suitable for use in the present invention are not particularly limited. For example, biphenol leuco dyes, phenol leuco dyes, indoaniline leuco dyes, acrylated azine leuco dyes, phenoxazine leuco dyes, phenodiazine leuco dyes. And phenothiazine leuco dye. Also useful are US Pat. Nos. 3,445,234, 3,846,136, 3,994,732, and 4,021,249. No. 4,021,250, No. 4,022,617, No. 4,123,282, No. 4,368,247, No. 4, No. 461,681 and JP-A-50-36110, 59-206931, JP-A-5-204087, 11-231460, JP-A-2002-169249, 2002-2002. Leuco dye disclosed in Japanese Patent No. 236334.

  In order to adjust to a predetermined color tone, it is preferable to use leuco dyes of various colors singly or in combination of a plurality of types, and to adjust the usage amount by using leuco dyes that develop yellow and cyan colors. Is preferred.

  The color density is preferably adjusted appropriately in relation to the color tone of the developed silver itself. In the present invention, the color tone may be adjusted so that the image has a reflection optical density of 0.01 to 0.05 or a transmission optical density of 0.005 to 0.50, and an image in the above preferable color tone range is obtained. preferable. In the present invention, the sum of the maximum densities at the maximum absorption wavelength of the dye image formed with the leuco dye is preferably 0.01 to 0.50, more preferably 0.02 to 0.30, and particularly preferably 0.0. It is preferable to develop the color so as to have 03 to 0.10. The maximum absorption wavelength of the dye image can be obtained by measuring the spectral absorption spectrum of the thermographic material after heat development.

(Yellow coloring leuco dye)
As described above, the thermographic material of the present invention adjusts the color tone using a leuco dye. In the present invention, a color image forming agent that is preferably used as a yellow chromophoric leuco dye is a color image forming agent that increases its absorbance at 360 nm to 450 nm when oxidized. These color image forming agents are particularly preferably color image forming agents represented by the following general formula (YA).

In the formula, R ₁₁ represents an alkyl group and R ₁₂ represents a hydrogen atom, an alkyl group or an acylamino group, but R ₁₁ and R ₁₂ are not a 2-hydroxyphenylmethyl group. R ₁₃ represents a hydrogen atom or an alkyl group, and R ₁₄ represents a substituent.

  Hereinafter, the compound of the general formula (YA) will be described in detail.

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

  Specifically, methyl group, ethyl group, butyl group, octyl group, iso-propyl group, tert-butyl group, tert-octyl group, tert-pentyl group, sec-butyl group, cyclohexyl group, 1-methyl-cyclohexyl group And a group sterically larger than the iso-propyl group (for example, iso-propyl group, iso-nonyl group, tert-butyl group, tert-amyl group, tert-octyl group, cyclohexyl group, 1-methyl- A cyclohexyl group, an adamantyl group, etc., among which a secondary or tertiary alkyl group is preferable, and a tertiary alkyl group such as a tert-butyl group, a tert-octyl group, or a tert-pentyl group is preferable. Particularly preferred.

Examples of the substituent that R ₁₁ may have include a halogen atom, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, a sulfonamido group, an acyloxy group, an oxycarbonyl group, and a carbamoyl group. , Sulfamoyl group, sulfonyl group, phosphoryl group and the like.

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

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

R ₁₃ represents a hydrogen atom or an alkyl group. The alkyl group is preferably an alkyl group having 1 to 30 carbon atoms, and the description of the alkyl group is the same as that for R ₁₁ . R ₁₃ is preferably a hydrogen atom or an alkyl group having 1 to 24 carbon atoms, and specific examples include a methyl group, an iso-propyl group, and a tert-butyl group. Moreover, it is preferable that any one of R < ₁₂ >, R < ₁₃ > is a hydrogen atom.

R ₁₄ represents a substituent, for example, an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, Pentadecyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (eg, vinyl group, allyl group, 1-propenyl group, ethenyl-2-propenyl group, butenyl group, 3-butenyl group) Group, 2-butenyl group, 1,3-butadienyl group, 3-pentenyl group, 2-pentenyl group, isopropenyl group, hexenyl group, hexadienyl group, 1-methyl-3-propenyl, 1-methyl-3-butenyl, etc. ), Alkynyl groups (eg, ethynyl group, propargyl group, etc.), aryl groups (eg, Group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, biphenylyl group), aromatic heterocyclic group (For example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group (for example, pyrrolidyl group, Imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (for example, Cyclo pliers Oxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc. ), Cycloalkylthio group (for example, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (for example, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (for example, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl) Group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, Aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2 -Pyridylaminosulfonyl group, etc.), acyl groups (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthyl) Carbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group) Group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexyl) Carbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl) Group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexyl Ruaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octyl) Ureido group, dodecylureido group, phenylureido group naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecyl) Sulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethyl Acetylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino Group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (for example, fluorine atom, Chlorine atom, bromine atom, etc.), fluorinated hydrocarbon group (eg, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, nitro group, hydroxy group, mercapto group, silyl Group (for example, Trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, a phenyl diethyl silyl group and the like), and the like. Among these, a particularly preferable substituent is an alkyl group.

  These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

R ₁₄ is preferably an alkyl group having 1 to 30 carbon atoms or an oxycarbonyl group having 2 to 30 carbon atoms, and more preferably an alkyl group having 1 to 24 carbon atoms. Examples of the substituent of the alkyl group include an aryl group, an amino group, an alkoxy group, an oxycarbonyl group, an acylamino group, an acyloxy group, an imide group, and a ureido group, and more preferable examples include an aryl group, an amino group, an oxycarbonyl group, and an alkoxy group. preferable. These alkyl group substituents may be further substituted with these substituents.

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

In the formula, Z represents —S— or —C (R ₂₁ ) (R ₂₁ ′) —, and R ₂₁ and R ₂₁ ′ each represents a hydrogen atom or a substituent.

Examples of the substituent represented by R ₂₁ and R ₂₁ ′ include the same groups as those described in the description of R ₁₄ . R ₂₁ and R ₂₁ ′ are preferably a hydrogen atom or an alkyl group.

R ₂₂ , R ₂₃ , R ₂₂ ′ and R ₂₃ ′ each represents a substituent, and examples of the substituent include an aryl group, a hydroxyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, and a sulfonamide group. Sulfonyl group, phosphoryl group, acyl group, carbamoyl group, ester group, halogen atom and the like. Preferably, both are secondary or tertiary alkyl groups, preferably having 2 to 20 carbon atoms. A tertiary alkyl group is more preferred, t-butyl, t-pentyl and 1-methylcyclohexyl are more preferred, and t-butyl is most preferred.

R ₂₂ , R ₂₃ , R ₂₂ ′ and R ₂₃ ′ are preferably an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, but an alkyl group is more preferable. Examples of the substituent on the alkyl group include the same groups as those described in the description of the substituent described in the description of R ₁₄ .

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

R ₂₄ and R ₂₄ ′ each represent a hydrogen atom or a substituent, and examples of the substituent include the same groups as those described in the description of R ₁₄ .

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

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

  The addition amount of the compound of general formula (YA) (including a hindered phenol compound and a compound represented by general formula (YB)) is preferably in the range of 0.00001 mol to 0.01 mol per mol of silver, More preferably, it is 0.0005 mol-0.01 mol, Most preferably, it is 0.001 mol-0.008 mol.

  Moreover, it is preferable that the addition amount ratio with respect to the sum total of the reducing agent of yellow coloring leuco dye is 0.001-0.2 by molar ratio, and it is more preferable that it is 0.005-0.1. In the thermographic material of the present invention, the sum of the maximum densities at the maximum absorption wavelength of a dye image formed with a yellow color-forming leuco dye is preferably 0.01 to 0.50, more preferably 0.02 to 0.00. The color is preferably adjusted to 30 to 30 and particularly preferably 0.03 to 0.10.

(Cyan coloring leuco dye)
The cyan color-forming leuco dye used in the present invention will be described.

  The thermographic material of the present invention is preferably adjusted in color tone using a cyan color-forming leuco dye.

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

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

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

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

  (Compound represented by general formula (CLA))

In the formula, are R ₃₁ and R ₃₂ a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkoxy group, or a —NHCO—R ₃₀ group (R ₃₀ represents an alkyl group, an aryl group, or a heterocyclic group)? Or R ₃₁ and R ₃₂ are groups which are linked to each other to form an aliphatic hydrocarbon ring, an aromatic hydrocarbon ring or a heterocyclic ring. A ₃ represents a —NHCO— group, a —CONH— group or a —NHCONH— group, and R ₃₃ represents an alkyl group, an aryl group or a heterocyclic group. W ₃ represents a hydrogen atom, a —CONH—R ₃₅ group, a —CO—R ₃₅ group or a —CO—O—R ₃₅ group (R ₃₅ represents an alkyl group, an aryl group or a heterocyclic group), and R _34. Represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkoxy group, a carbamoyl group, or a nitrile group. R ₃₆ represents —CONH—R ₃₇ group, —CO—R ₃₇ group or —CO—O—R ₃₇ group (R ₃₇ represents an alkyl group, aryl group or heterocyclic group) X ₃ represents an aryl group, Represents a heterocyclic group.

In the general formula (CLA), examples of the halogen atom represented by R ₃₁ and R ₃₂ include a fluorine atom, a bromine atom, and a chlorine atom, and the alkyl group includes an alkyl group having up to 20 carbon atoms (for example, Methyl group, ethyl group, butyl group, dodecyl group, etc.). Examples of the alkenyl group include alkenyl groups having up to 20 carbon atoms (for example, vinyl group, allyl group, butenyl group, hexenyl group, hexadienyl group, ethenyl-2-ethyl group). A propenyl group, a 3-butenyl group, a 1-methyl-3-propenyl group, a 3-pentenyl group, a 1-methyl-3-butenyl group, and the like. As the alkoxy group, an alkoxy group having up to 20 carbon atoms (for example, methoxy) Group, ethoxy and the like). Examples of the alkyl group represented by R ₃₀ in the —NHCO—R ₃₀ group include alkyl groups having up to 20 carbon atoms (for example, a methyl group, an ethyl group, a butyl group, a dodecyl group, etc.), and an aryl group. Examples thereof include a group having 6 to 20 carbon atoms such as a phenyl group and a naphthyl group, and examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group. The alkyl group represented by R ₃₃ is preferably an alkyl group having up to 20 carbon atoms, and examples thereof include a methyl group, an ethyl group, a butyl group, and a dodecyl group, and the aryl group preferably has 6 to 20 carbon atoms. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group.

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

Examples of the halogen atom represented by R ₃₄ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkyl group include a chain or cyclic alkyl group such as a methyl group, a butyl group, and dodecyl. Group, cyclohexyl group and the like. Examples of the alkenyl group include alkenyl groups having up to 20 carbon atoms (for example, vinyl group, allyl group, butenyl group, hexenyl group, hexadienyl group, ethenyl-2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl, etc.), and alkoxy groups include, for example, methoxy group, butoxy group, tetradecyloxy group, etc., and carbamoyl Examples of the group include a diethylcarbamoyl group and a phenylcarbamoyl group. Nitrile groups are also preferred. Among these, a hydrogen atom and an alkyl group are more preferable. R ₃₃ and R ₃₄ may be connected to each other to form a ring structure. The above groups can further have a single substituent or multiple substituents. Typical substituents include halogen atoms (eg, fluorine atom, chlorine atom, bromine atom), alkyl groups (eg, methyl group, ethyl group, propyl group, butyl group, dodecyl group), hydroxy group, cyano Group, nitro group, alkoxy group (for example, methoxy group, ethoxy group, etc.), alkylsulfonamide group (for example, methylsulfonamide group, octylsulfonamide group, etc.), arylsulfonamide group (for example, phenylsulfonamide group, naphthyl) Sulfonamide group etc.), alkylsulfamoyl group (eg butylsulfamoyl group etc.), arylsulfamoyl (eg phenylsulfamoyl group etc.), alkyloxycarbonyl group (eg methoxycarbonyl group etc.), An aryloxycarbonyl group (eg phenyloxycarbonyl) Group), amino sulfonamido group, an acylamino group, a carbamoyl group, a sulfonyl group, a sulfinyl group, a sulfoxy group, a sulfo group, an aryloxy group, an alkoxy group, an alkylcarbonyl group, arylcarbonyl group, and an amino carbonyl group.

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

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

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

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

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

  These groups may include photographically useful groups.

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

  (Compound represented by general formula (CLB))

In the formula, R ₄₁ , R ₄₂ , R _4a and R _4b each independently represent a hydrogen atom, an aliphatic group, an aromatic group, an alkoxy group, an aryloxy group, an acylamino group, a sulfonamide group, a carbamoyl group, or a halogen atom. . R ₄₃ represents a hydrogen atom, an aliphatic group, an aromatic group, an acyl group, an alkoxycarbonyl group, an aryloxycarboquinyl group, a carbamoyl group, a sulfamoyl group, or a sulfonyl group. X ₄₁ and X ₄₂ represents a substituent. m41 and m42 represent an integer of 0 to 5.

When there are a plurality of X ₄₁ and X ₄₂ , each X ₄₁ and X ₄₂ may be the same or different.

In the general formula (CLB), specific examples of the aliphatic group represented by R ₄₁ , R ₄₂ , R _4a, and R _4b include hydrocarbon groups such as an alkyl group, an alkenyl group, and an alkynyl group. These hydrocarbon groups preferably have 1 to 25 carbon atoms, and more preferably 1 to 20 carbon atoms. Examples of the alkyl group having 1 to 25 carbon atoms include a methyl group, an ethyl group, a propyl group, an iso-propyl group, a tert-butyl group, a pentyl group, and a hexyl group, such as a cycloalkyl group (for example, a cyclohexyl group and a cyclopentyl group). Alkenyl group (for example, ethenyl-2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, etc.), alkynyl group ( For example, an ethynyl group, a 1-propynyl group, a propargyl group, etc.) can be mentioned.

Specific examples of the aromatic group represented by R ₄₁ , R ₄₂ , R _4a and R _4b include aryl groups (also referred to as aromatic hydrocarbon groups, aromatic carbocyclic groups, etc.) (for example, phenyl groups, Naphthyl group, etc.), heterocyclic groups (for example, pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, sulfolanyl group, piperidinyl group, pyrazolyl group, Tetrazolyl group, etc.).

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Specific examples of the substituent represented by X ₄₁ and X ₄₂ include an alkyl group having 1 to 25 carbon atoms (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, Cyclohexyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group, etc.), alkenyl group (vinyl, allyl, butenyl, hexenyl, hexadienyl, ethenyl-2-propenyl, 3-butenyl, 1-methyl-3-propenyl, 3- Pentenyl, 1-methyl-3-butenyl, etc.), alkynyl group (ethynyl, propargyl group, etc.), glycidyl group, acrylate group, methacrylate group, aryl group (phenyl group etc.), aryl group (phenyl, naphthyl group etc.), complex Ring group (pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, furyl group, Loryl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, sriphoranyl group, piperidinyl group, pyrazolyl group, tetrazolyl group, etc.), halogen atom (chlorine atom, bromine atom, iodine atom, fluorine atom etc.), alkoxy group (methoxy) Group, ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group, hexyloxy group, cyclohexyloxy group, etc.), aryloxy group (phenoxy group etc.), alkoxycarbonyl group (methyloxycarbonyl group, ethyloxycarbonyl group, Butyloxycarbonyl group), aryloxycarbonyl group (phenyloxycarbonyl group, etc.), sulfonamide group (methanesulfonamide group, ethanesulfonamide group, butanesulfonamide group, hexanesulfonamide group, Rohexanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl group (aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, phenylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), urethane group (methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, phenylureido group, 2-pyridylureido group etc.), acyl group (acetyl group, propionyl group, butanoyl group) , Hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), carbamoyl group (aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propyl) Aminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), amide group (acetamido group, propionamide group, butanamide group, hexaneamide group, benzamide group, etc.), alkyl Sulfonyl group or arylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group), sulfonamide group (for example, methylsulfonamide group, octylsulfone) Amide group, phenylsulfonamide group, naphthylsulfonamide group, etc.), amino group (amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group) An anilino group, 2-pyridylamino group), a cyano group, a nitro group, a sulfo group, a carboxy group, hydroxy group, can be exemplified Okizamoiru group. Further, these groups may be further substituted with these groups.

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

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

  The compound represented by the general formula (CLB) can be synthesized with reference to the description of a conventionally known method, for example, Japanese Patent Publication No. 7-45477.

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

  The addition amount of the cyan coloring leuco dye is usually 0.00001 mol / Ag 1 mol to 0.05 mol / Ag 1 mol, preferably 0.0005 mol / Ag 1 mol to 0.02 mol / Ag 1 mol, more preferably 0.001 mol / Ag1 mol to 0.01 mol / Ag1 mol. The addition ratio of the cyan color-forming leuco dye to the total of the reducing agents is preferably 0.001 to 0.2, more preferably 0.005 to 0.1, in terms of molar ratio.

  In the thermographic material of the present invention, the sum of the highest densities at the maximum absorption wavelength of the dye image formed by the cyan leuco dye is preferably 0.01 to 0.50, more preferably 0.02 to 0.30, particularly It is preferable to develop the color so as to have 0.03 to 0.10.

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

The compounds represented by the general formulas (YA) and (YB) and the coloring leuco dye can be added by the same method as the reducing agent addition method. You may make it contain in a coating liquid by arbitrary methods, such as a dispersion form, and may make it contain in a thermographic material.
The reducing agent, the compounds of the general formulas (YA) and (YB), and the cyan color-forming leuco dye are preferably contained in the image forming layer containing an organic silver salt, but one is used for the image forming layer and the other is used for the image forming. You may make it contain in the non-image forming layer adjacent to a layer, and may make both contain in a non-image forming layer.
Further, when the image forming layer is composed of a plurality of layers, they may be contained in separate layers.

《Reducing agent》
The reducing agent according to the present invention will be described.

  The reducing agent according to the present invention is capable of reducing silver ions in the image forming layer during heat development, and is also referred to as a developer.

  In the thermographic material according to the invention, as reducing agent, an organic compound containing at least one active hydrogen atom bonded to O, N or C, as is the case with aromatic di- and tri-hydroxy compounds It is preferable that 1,2-dihydroxy-benzene derivatives such as catechol, 3- (3,4-dihydroxyphenyl) propionic acid, 1,2-dihydroxybenzoic acid, phenol, hindered phenol, pyrogallol (1,2,3, trihydroxybenzene ), Ascorbic acid derivatives, gallic acid and esters, such as methyl gallate, ethyl gallate, propyl gallate, tannic acid and 3,4-dihydroxy-benzoic acid esters are preferred, such as EP 0697333 and Those described in EP-A-0903625 are particularly preferred.

Combinations of reducing agents that when heated can be reactive partners in the reduction of one or more substantially light-insensitive organic silver salts can also be used. For example, combinations of sterically hindered phenols and sulfonyl hydrazide reducing agents as disclosed in US Pat. No. 5,464,738; disclosed in US Pat. No. 5,496,695. Trityl hydrazide and formyl-phenyl-hydrazide as described in U.S. Pat. No. 5,545,505, U.S. Pat. No. 5,545,507 and U.S. Pat. No. 5,558,983. Trityl hydrazide and formyl-phenyl-hydrazide as disclosed and various auxiliary reducing agents; as disclosed in US Pat. No. 5,545,515 and US Pat. No. 5,635,339 Acrylonitrile compounds; and 2-substituted malonodia as disclosed in US Pat. No. 5,654,130 Dehydro compounds. The amount of the reducing agent used is preferably 1 × 10 ⁻² to 10 mol, particularly preferably 1 × 10 ^{−2 to} 1.5 mol, per mol of silver.

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

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

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

  In the present invention, among these aliphatic carboxylic acid silvers, the silver behenate content is preferably 50 mol% or more, more preferably 80 mol% to 100 mol% or less, based on the total aliphatic carboxylic acid silver. It is preferable to use 90 to 99.99 mol% of fatty acid silver.

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

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

  The average sphere equivalent diameter of the non-photosensitive aliphatic carboxylic acid silver salt means the diameter of the sphere having the same volume as the volume of one particle of the non-photosensitive aliphatic carboxylic acid silver salt. The particle volume can be obtained from the projected area and thickness of the particles observed by the above, and the diameter when converted to a sphere having the same volume as that volume can be obtained by averaging. In order to control the average sphere equivalent diameter of the non-photosensitive aliphatic carboxylic acid silver salt, it is necessary to increase the potassium salt ratio during preparation of the aliphatic carboxylic acid silver salt as described above, or to disperse the image forming layer. This can be easily performed by appropriately adjusting the particle diameter, mill peripheral speed, and dispersion time of the zirconia beads used during dispersion of the liquid. In the present invention, the average sphere equivalent diameter of the non-photosensitive aliphatic carboxylic acid silver salt is preferably 0.05 μm to 0.50 μm, more preferably 0 in order to obtain a sufficient density after heat development. .10 μm to 0.45 μm, particularly preferably 0.15 μm to 0.40 μm.

  In addition to the non-photosensitive aliphatic carboxylic acid silver salt used in the present invention, the organic silver that may be used as necessary includes an organic silver salt having a core-shell structure (for example, JP-A-2002-23303), Silver salt of polyvalent carboxylic acid (for example, EP1246001 and JP2004-061948), polymer silver salt (for example, JP2000-292881, JP2003-295378-2003-295811, etc.) Can also be used.

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

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

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

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

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

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

The organic silver salt of the present invention can be used in a desired amount, preferably 0.1g / m ² ~5g / m ² as silver amount, more preferably ^{0.3g / m 2 ~3g / m 2} , more preferably it is ^{0.5g / m 2 ~2g / m 2} .

(binder)
In the thermographic material of the present invention, the image forming layer and the non-image forming layer according to the present invention can contain a binder for various purposes.

  The binder contained in the image forming layer according to the present invention is capable of supporting an organic silver salt, silver halide grains, a reducing agent, and other components. Suitable binders are transparent or translucent and generally colorless. Yes, natural polymers, synthetic polymers, copolymers, and other media for forming a film, for example, those described in paragraph “0069” of JP-A No. 2001-330918.

  Among these, preferred binders for the image forming layer are polyvinyl acetals, and particularly preferred is polyvinyl butyral. These will be described in detail later.

  For non-image forming layers such as overcoat layers and undercoat layers, especially protective layers and backcoat layers, cellulose esters that are polymers with higher softening temperatures, especially polymers such as triacetyl cellulose and cellulose acetate butyrate Is preferred. In addition, as needed, said binder can be used in combination of 2 or more type.

The binder includes —COOM, —SO ₃ M, —OSO ₃ M, —P═O (OM) ₂ , —O—P═O (OM) ₂ , —N (R) ₂ , —N ⁺ (R) _3. (M represents a hydrogen atom or an alkali metal base, R represents a hydrocarbon group), a copolymer in which at least one polar group selected from an epoxy group, —SH, —CN, etc. is introduced by copolymerization or addition reaction It is preferable to use, and —SO ₃ M and —OSO ₃ M are particularly preferable. The amount of such a polar group is 1 × 10 ⁻¹ to 1 × 10 ⁻⁸ mol / g, preferably 1 × 10 ⁻² to 1 × 10 ⁻⁶ mol / g.

  Such a binder is used in an effective range to function as a binder.

The effective range can be easily determined by one skilled in the art. For example, as an index for holding at least the organic silver salt in the image forming layer (image forming layer), the ratio of the binder to the organic silver salt is preferably 15: 1 to 1: 2 (mass ratio), and particularly 8: A range of 1-1: 1 is preferred. That is, the binder amount of the photosensitive layer is preferably from the viewpoint of suppressing the increase in the concentration of the unexposed portion is ^{1.5g / m 2 ~6g / m 2} , more preferably 1.7 g / m ² to 5 g / M ² .

  It is preferable that the glass transition temperature (Tg) of the binder used by this invention is 70 to 105 degreeC. Tg can be obtained by measuring with a differential scanning calorimeter, and the intersection of the baseline and the endothermic peak slope is defined as Tg. Tg in the present invention is determined by the method described in “Polymer Handbook” III-139-179 (1966, Wiley and Sun, Inc.) by Brand Wrap et al.

  Tg when the binder is a copolymer resin is obtained by the following formula.

Tg (copolymer) (° C.) = V ₁ Tg ₁ + v ₂ Tg ₂ +... + V _n Tg _{n
Wherein, v 1, v 2 ··· v} n represents the mass fraction of the monomer in the _{copolymer, Tg 1, Tg 2 ··· Tg} n from each monomer in the copolymer Tg (° C.) of the obtained single polymer is represented. The accuracy of Tg calculated according to the above equation is ± 5 ° C.

  Use of a binder having a Tg of 70 ° C. to 105 ° C. is preferable because a sufficient maximum density can be obtained in image formation.

  The binder according to the present invention has a Tg of 70 ° C. to 105 ° C., a number average molecular weight of 1,000 to 1,000,000, preferably 10,000 to 500,000, and a degree of polymerization of about 50 to 1,000. belongs to. Examples of the polymer or copolymer containing an ethylenically unsaturated monomer as a constituent unit include those described in paragraph No. “0069” of JP-A No. 2001-330918.

  Of these, particularly preferred examples include methacrylic acid alkyl esters, methacrylic acid aryl esters, and styrenes. Among such polymer compounds, a polymer compound having an acetal group is preferably used. Even a polymer compound having an acetal group is more preferably a polyvinyl acetal having an acetoacetal structure. For example, U.S. Pat. Nos. 2,358,836, 3,003,879, and Examples thereof include polyvinyl acetals shown in 2,828,204 specification, British Patent 771,155 specification and the like.

  As the polymer compound having an acetal group, a compound represented by the general formula (V) described in [150] of JP-A No. 2002-287299 is particularly preferable.

As the polyurethane resin that can be used in the present invention, known resins such as polyester polyurethane, polyether polyurethane, polyether polyester polyurethane, polycarbonate polyurethane, polyester polycarbonate polyurethane, and polycaprolactone polyurethane can be used. Moreover, it is preferable to have a total of 2 or more hydroxy groups, at least one at each polyurethane molecule end. Since the hydroxy group is cross-linked with a polyisocyanate as a curing agent to form a three-dimensional network structure, the hydroxy group is more preferably contained in the molecule. In particular, it is preferable that the hydroxy group is at the molecular end because the reactivity with the curing agent is high. The polyurethane preferably has 3 or more hydroxy groups at the molecular terminals, and particularly preferably 4 or more. In the present invention, when polyurethane is used, Tg is 70 ° C. to 105 ° C., an elongation at break of 100% to 2000%, breaking stress is 0.5N / mm ² ~100N / mm ² is preferred.

  These polymer compounds (polymers) may be used alone or in a blend of two or more.

  In the image forming layer according to the present invention, the polymer is preferably used as a main binder. The main binder here refers to “a state in which the polymer occupies 50% by mass or more of the total binder in the image forming layer”. Therefore, other polymers may be blended and used within a range of less than 50% by weight of the total binder. These polymers are not particularly limited as long as they can be arbitrarily mixed with the polymer of the present invention. More preferably, a polyvinyl acetate, a polyacryl resin, a urethane resin, etc. are mentioned.

  An organic gelling agent may be contained in the image forming layer. Incidentally, the organic gelling agent referred to here has a function of giving a yield value to the system by adding it to an organic liquid, such as polyhydric alcohols, and eliminating or reducing the fluidity of the system. The compound which has.

  It is also a preferred embodiment that the image forming layer coating solution contains an aqueous dispersed polymer latex. In this case, a polymer latex in which 50% by mass or more of the total binder in the coating solution for the image forming layer is dispersed in water is preferable. Further, when a polymer latex is used in the preparation of the image forming layer, 50% by mass or more of the total binder in the image forming layer is preferably a polymer latex-derived polymer, and more preferably 70% by mass or more.

  Here, the polymer latex is a water-insoluble hydrophobic polymer dispersed as fine particles in a water-soluble dispersion medium. As the dispersion state, the polymer is emulsified in a dispersion medium, the emulsion is polymerized, the micelle is dispersed, or the polymer molecule has a partially hydrophilic structure, and the molecular chain itself is molecularly dispersed. Any of these may be used. The average particle diameter of the dispersed particles is preferably 1 to 50,000 nm, more preferably in the range of about 5 to 1,000 nm. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution.

  The polymer latex that can be used in the thermographic material of the present invention may be a so-called core / shell type latex other than a normal polymer latex having a uniform structure. In this case, it may be preferable to change the Tg of the core and the shell. The minimum film-forming temperature (MFT) of the polymer latex according to the present invention is preferably -30 ° C to 90 ° C, more preferably about 0 ° C to 70 ° C. Further, a film-forming auxiliary may be added to control the minimum film-forming temperature.

  The film-forming aid, also called a plasticizer, is an organic compound (usually an organic solvent) that lowers the minimum film-forming temperature of polymer latex. For example, “Synthetic Latex Chemistry (Souichi Muroi, published by Polymer Publishing Co., Ltd.) , 1970).

  Examples of the polymer species used for the polymer latex include acrylic resins, vinyl acetate resins, polyester resins, polyurethane resins, rubber resins, vinyl chloride resins, vinylidene chloride resins, polyolefin resins, and copolymers thereof. The polymer may be a linear polymer, a branched polymer, or a crosslinked polymer. The polymer may be a so-called homopolymer in which a single monomer is polymerized or a copolymer in which two or more monomers are polymerized. In the case of a copolymer, it may be a random copolymer or a block copolymer. The molecular weight of the polymer is a number average molecular weight and is usually about 5,000 to 1,000,000, preferably about 10,000 to 100,000. When the molecular weight is too small, the mechanical strength of the image forming layer is insufficient, and when the molecular weight is too large, the film forming property is poor and both are not preferable.

  The polymer latex preferably has an equilibrium water content at 25 ° C. and 60% RH (relative humidity) of 0.01% by mass to 2% by mass, more preferably 0.01% by mass to 1% by mass. It is. For the definition and measurement method of the equilibrium moisture content, for example, “Polymer Engineering Course 14, Polymer Material Testing Method (Edited by Polymer Society, Jinshokan)” can be referred to.

  Specific examples of the polymer latex include each latex described in “0173” of JP-A No. 2002-287299. These polymers may be used alone or in combination of two or more as required. As a polymer seed | species of a polymer latex, what contains about 0.1 mass%-10 mass% of carboxylic acid components, such as an acrylate or a methacrylate component, is preferable.

  Furthermore, if necessary, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose or the like may be added within a range of 50% by mass or less of the total binder. The addition amount of these hydrophilic polymers is preferably 30% by mass or less based on the total binder of the image forming layer.

  Regarding the order of addition of the organic silver salt and the aqueous dispersed polymer latex in the preparation of the coating solution for the image forming layer, any of these may be added first or simultaneously, but preferably the polymer latex is used. Later.

  Furthermore, it is preferable that an organic silver salt and further a reducing agent are mixed before adding the polymer latex. In addition, after mixing the organic silver salt and the polymer latex, if the temperature for aging is too low, the coating surface shape is impaired, and if it is too high, there is a problem that fog increases, so the coating solution after mixing is 30 ° C. to 65 ° C. It is preferable that the above time is elapsed. Furthermore, it is preferable that the aging is performed at 35 ° C. to 60 ° C., and the aging at 35 ° C. to 55 ° C. is particularly preferable. In order to maintain the temperature in this way, it is sufficient to keep the temperature of the coating solution preparation tank or the like.

  For coating of the image forming layer coating solution, it is preferable to use a coating solution that has been mixed for 30 minutes to 24 hours after mixing the organic silver salt and the aqueous dispersed polymer latex, and more preferably, 60 minutes after mixing. It is to make -12 hours pass, and it is especially preferable to use the coating liquid which passed 120 minutes-10 hours.

  Here, “after mixing” means after the organic silver salt and the aqueous polymer latex are added and the additive material is uniformly dispersed.

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

  As the crosslinking agent used, various crosslinking agents conventionally used for photographic thermographic materials, for example, aldehyde-based, epoxy-based, ethyleneimine-based, vinylsulfone-based, described in JP-A-50-96216, Sulfonic acid ester-based, acryloyl-based, carbodiimide-based, and silane compound-based crosslinking agents are used, and preferred are isocyanate-based, silane compound-based, epoxy-based compounds, and acid anhydrides shown below.

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

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

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

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

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

  Examples of the silane compound include compounds represented by general formulas (1) to (3) disclosed in JP-A-2001-264930.

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

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

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

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

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

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

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

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

  Specific examples of the quaternary onium compound include triphenyltetrazolium.

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

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

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

General formula (SE1)
Q ₁ -NHNH-Q ₂
In the formula, Q ₁ represents an aromatic group or a heterocyclic group bonded to —NHNH—Q ₂ at a carbon atom, and Q ₂ represents a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, An arylsulfonyl group or a sulfamoyl group is represented.

In the general formula (SE1), the aromatic group or heterocyclic group represented by Q ₁ is preferably a 5- to 7-membered unsaturated ring. Preferred examples include benzene ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, 1,2,4-triazine ring, 1,3,5-triazine ring, pyrrole ring, imidazole ring, pyrazole ring, 1,2 , 3-triazole ring, 1,2,4-triazole ring, tetrazole ring, 1,3,4-thiadiazole ring, 1,2,4-thiadiazole ring, 1,2,5-thiadiazole ring, 1,3,4 -Oxadiazole ring, 1,2,4-oxadiazole ring, 1,2,5-oxadiazole ring, thiazole ring, oxazole ring, isothiazole ring, isoxazole ring, thiophene ring, etc. are preferable, and these Also preferred are fused rings in which the rings are fused together.

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

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

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

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

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

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

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

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

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

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

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

(Thermal solvent)
The thermographic material of the present invention preferably contains a thermal solvent. Here, the thermal solvent is defined as a material capable of lowering the heat development temperature by 1 ° C. or more as compared with a thermographic material that does not contain a thermal solvent with respect to the thermal solvent-containing thermographic material. More preferably, the material can lower the heat development temperature by 2 ° C. or more, and particularly preferably the material that can lower the temperature by 3 ° C. or more.

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

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

  Y may further have a substituent, and may have a group represented by Z as a substituent. Y will be described in more detail. In general formula (TS), Y is a linear, branched or cyclic alkyl group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 25 carbon atoms such as a methyl group or an ethyl group. N-propyl group, iso-propyl group, sec-butyl group, tert-butyl group, tert-octyl group, n-amyl group, tert-amyl group, n-dodecyl group, n-tridecyl group, octadecyl group, icosyl Group, docosyl group, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 25 carbon atoms such as vinyl group and allyl group). Group, 2-butenyl group, 3-pentenyl group, etc.), aryl group (preferably having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms). Preferably they are 6-25, for example, a phenyl group, p-methylphenyl group, a naphthyl group etc. are mentioned), a heterocyclic group (preferably C2-C20, More preferably, 2-16, Especially preferably, 2-12, and examples thereof include a pyridyl group, a pyrazyl group, an imidazolyl group, and a pyrrolidyl group. These substituents may be further substituted with other substituents.

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

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

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

In the present invention, the amount of hot solvent is preferably in a range of from ^{0.01g / m 2 ~5.0g / m 2} , more preferably from ^{0.05g / m 2 ~2.5g / m 2} , more preferably is ^{0.1g / m 2 ~1.5g / m 2} .

  The thermal solvent is preferably contained in the image forming layer. Moreover, although the said thermal solvent may be used independently, you may use it in combination of 2 or more type. In the present invention, the thermal solvent may be contained in the coating liquid by any method such as a solution form, an emulsified dispersion form, or a solid fine particle dispersion form, and may be contained in the thermographic material.

  As a conventionally known emulsification dispersion method, an emulsion such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate is dissolved using an auxiliary solvent such as ethyl acetate or cyclohexanone to mechanically prepare an emulsion dispersion. A method is mentioned.

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

(Anti-fogging and image stabilizer)
In any constituent layer of the thermographic material of the present invention, an antifoggant for preventing fogging during storage before heat development, and an image stabilizer for preventing image deterioration after heat development are provided. It is preferable to make it contain.

  The antifogging and image stabilizer that can be used in the thermographic material of the present invention will be described.

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

  When the reducing agent used in the present invention has an aromatic hydroxy group (—OH), particularly in the case of bisphenols, a non-reducing compound having a group capable of forming a hydrogen bond with these groups It is preferable to use together.

  Specific examples of particularly preferred hydrogen bonding compounds in the present invention include, for example, compounds (II-1) to (II-40) described in paragraphs [0061] to [0064] of JP-A-2002-90937. Is mentioned.

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

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

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

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

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

(Toning agent)
The thermographic material of the present invention forms a photographic image by heat development processing, and contains a toning agent (toner) for adjusting the color tone of silver as needed dispersed in a normal (organic) binder matrix. It is preferable.

  Examples of suitable toning agents used in the present invention include Research Disclosure (RD) 17029, U.S. Pat. Nos. 4,123,282, 3,994,732, and 3, No. 846,136 and No. 4,021,249, and the like, for example.

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

(Fluorosurfactant)
In the present invention, a fluorine-based surfactant represented by the following general formula (SF) is preferably used in order to improve film transportability and environmental suitability (accumulation in a living body) in a thermal printer (heat development processing apparatus). It is done.

General formula (SF)
(R _f − (L ₁ ) _n1 −) _p − (Y) _m1 − (A) _q
In the formula, R _f represents a substituent containing a fluorine atom, L ₁ represents a divalent linking group having no fluorine atom, Y represents a (p + q) -valent linking group having no fluorine atom, A represents an anionic group or a salt thereof, n1 and m1 each represents an integer of 0 or 1, p represents an integer of 1 to 3, and q represents an integer of 1 to 3. However, when q is 1, n1 and m1 are not 0 at the same time.

In the general formula (SF), R _f represents a substituent containing a fluorine atom. Examples of the substituent containing a fluorine atom include a fluorinated alkyl group having 1 to 25 carbon atoms (for example, a trifluoromethyl group). Trifluoroethyl group, perfluoroethyl group, perfluorobutyl group, perfluorooctyl group, perfluorododecyl group and perfluorooctadecyl group) or fluorinated alkenyl group (for example, perfluoropropenyl group, perfluorobutenyl group, Perfluorononenyl group, perfluorododecenyl group, etc.). R _f preferably has 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms. R _f preferably has 2 to 12 fluorine atoms, more preferably 3 to 12 fluorine atoms.

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

  A represents an anionic group or a salt thereof, and examples thereof include a carboxylic acid group or a salt thereof (sodium salt, potassium salt and lithium salt), a sulfonic acid group or a salt thereof (sodium salt, potassium salt and lithium salt), sulfuric acid Examples thereof include a half ester group or a salt thereof (sodium salt, potassium salt and lithium salt), and a phosphoric acid group or a salt thereof (sodium salt and potassium salt).

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

The fluorine-based surfactant represented by the general formula (SF) is an alkyl compound having 1 to 25 carbon atoms into which a fluorine atom is introduced (for example, trifluoromethyl group, pentafluoroethyl group, perfluorobutyl group, perfluorooctyl). Group and a compound having a perfluorooctadecyl group) and an alkenyl compound (for example, a perfluorohexenyl group and a perfluorononenyl group), a trivalent to hexavalent alkanol compound in which no fluorine atom is introduced, and a hydroxy group, respectively. A compound obtained by addition reaction or condensation reaction with an aromatic compound or hetero compound having 3 to 4 (partially _Rf -converted alkanol compound) is further converted into an anionic group (A) by, for example, sulfate esterification. Can be obtained.

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

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

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

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

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

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

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

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

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

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

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

1) Type of matting agent (inorganic or organic powder) contained in the layer on the side having the image forming layer and the layer opposite to the side having the image forming layer, average particle size, addition amount, surface treatment method 2) Matting agent Dispersion conditions (type of disperser used, dispersion time, type of beads used for dispersion, average particle size, type and amount of dispersant used during dispersion, type of polar group of binder, polar group content)
3) Drying conditions at the time of application (application speed, distance from the application surface of the hot air blowing nozzle, amount of dry air), residual solvent amount 4) Type of filter used for filtering the coating liquid, filtration time 5) Calendar treatment after application Are carried out under the conditions (for example, calendar temperature 40 ° C. to 80 ° C., pressure 490 N / cm (50 kg / cm) to 2940 N / cm (300 kg / cm), line speed 20 m / min to 100 m / min, nip number 2 6) In the present invention, the value of Rz (E) / Rz (B) is preferably 0.1 to 0.7, and particularly the value of Rz (E) / Rz (B) is 0.2 to 0. .6 is preferable, and 0.3 to 0.55 is more preferable. Here, (E) represents the outermost surface on the image forming layer side, and (B) represents the outermost surface on the back coat layer side opposite to the image forming layer. By setting it as this range, the transportability of the film is good, and the occurrence of uneven density during thermal development can be remarkably improved.

  In the present invention, the value of Ra (E) / Ra (B) is preferably 0.6 to 1.5, and particularly the value of Ra (E) / Ra (B) is 0.6 to 1. .3 is preferable, and 0.7 to 1.1 is more preferable. By setting it within this range, the increase in fog over time is small, the transportability of the film is good, and the occurrence of uneven density during thermal development can be further improved.

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

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

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

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

1) Objective lens: × 10.0, Intermediate lens: × 1.0
2) Measurement range: 463.4 μm × 623.9 μm
3) Pixel size: 368 × 238
4) Filter: Cylindrical correction and tilt correction 5) Smoothing: Medium smoothing 6) Scanning speed: Low
Ra, Rz, and Rt were defined according to JIS surface roughness (B 0601). For each sample of 10 cm × 10 cm, the sample was divided into 100 in a grid pattern at 1 cm intervals, the center of each square region was measured, and the average value was obtained from 100 measurements.

  In the present invention, the case where the layer containing the matting agent is the outermost layer is one of the preferred embodiments. That is, even when a non-image forming layer is provided on the image forming layer side of the thermographic material of the present invention or on the opposite side of the image forming layer with the support sandwiched, the outermost layer is used for controlling the surface roughness, etc. It is preferable to use organic or inorganic powder as the matting agent.

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

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

  In the present invention, it is preferable that the surface treatment is performed with an Si compound or an Al compound. When such a surface-treated powder is used, the dispersion state when the matting agent is dispersed can be improved. The content of Si or Al is preferably 0.1% by mass to 10% by mass of Si and 0.1% by mass to 10% by mass of Al, more preferably Si. 0.1 mass% to 5 mass%, Al is 0.1 mass% to 5 mass%, Si is 0.1 mass% to 2 mass%, Al is 0.1 mass% to 2 mass% Is particularly preferred. The mass ratio of Si and Al is preferably Si <Al. The surface treatment can be performed by the method described in JP-A-2-83219.

  The average particle diameter of the powder in the present invention is the average diameter in the case of spherical powder, the average major axis length in the case of acicular powder, and the maximum diagonal length of the plate-like surface in the case of plate-like powder. Mean values can be easily obtained from measurement with an electron microscope.

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

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

  The addition amount is usually 1.0% by mass to 20% by mass, preferably 2.0% by mass to 15% by mass with respect to the amount of binder used for the outermost layer (including the crosslinking agent in the binder amount), More preferably, it is 3.0 mass%-10 mass%.

  The average particle diameter of the organic or inorganic powder contained in the outermost layer on the side opposite to the image forming layer across the support is usually 2.0 μm to 15.0 μm, preferably 3.0 μm to 12.0 μm. More preferably, it is 4.0 μm to 10.0 μm. The addition amount is usually 0.2% by mass to 10% by mass, preferably 0.4% by mass to 7% by mass, with respect to the amount of binder used in the outermost layer (including the crosslinking agent in the binder amount), More preferably, it is 0.6 mass%-5 mass%.

  The variation coefficient of the particle size distribution is preferably 50% or less, more preferably 40% or less, and particularly preferably 30% or less. Here, the variation coefficient of the particle size distribution is a value represented by the following equation.

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

(Dye, pigment)
In the thermographic material of the present invention, a filter layer is formed on the same side as or opposite to the image forming layer in order to control the amount of light transmitted through the image forming layer or the wavelength distribution, or a dye or pigment is formed on the image forming layer. It is preferable to contain.

  As the dye used, known compounds that absorb light in various wavelength regions can be used.

(Support)
Examples of the support material used in the thermographic material of the present invention include various polymer materials, glass, wool cloth, cotton cloth, paper, metal (aluminum, etc.) and the like. What can be processed into a flexible sheet or roll is preferred. Therefore, as a support in the thermographic material of the present invention, cellulose acetate film, polyester film, polyethylene terephthalate (PET) film, polyethylene naphthalate (PEN) film, polyamide film, polyimide film, cellulose triacetate film (TAC) or polycarbonate ( PC) film or the like is preferable, and a biaxially stretched PET film is particularly preferable. The thickness of the support is about 50 μm to 300 μm, preferably 70 μm to 180 μm.

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

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

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

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

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

  As a binder used in these protective layers and backcoat layers, a polymer having a glass transition point (Tg) higher than that of the image forming layer and hardly causing scratches or deformation, such as cellulose acetate, cellulose acetate butyrate, cellulose acetate propio. Polymers such as nates are selected from the binders described above.

  For gradation adjustment or the like, two or more image forming layers may be provided on one side of the support or one or more layers on both sides of the support.

(Application of component layers)
The thermographic material of the present invention is preferably formed by preparing a coating solution in which the above-described constituent materials are dissolved or dispersed in a solvent, applying a plurality of these coating solutions simultaneously, and then performing a heat treatment. Here, "multiple simultaneous multi-layer coating" means that a coating solution for each constituent layer (for example, an image forming layer, a protective layer) is prepared, and each layer is repeatedly coated and dried when it is coated on a support. Instead, it means that each constituent layer can be formed in such a state that a multilayer coating and drying process can be performed simultaneously. That is, the upper layer is provided before the remaining amount of all the solvents in the lower layer reaches 70% by mass or less (more preferably 90% by mass or less).

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

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

In the present invention, it is preferable to select an appropriate amount according to the purpose of the thermographic material in the present invention. However, for the purpose of medical images, 0.3 g / m ² or more, 1.5 g / m ² The following is preferable, and 0.5 g / m ² or more and 1.5 g / m ² or less are more preferable.

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

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

In the present invention, preferably the thermographic material is contained in a range of solvents 5mg / m ² ~1,000mg / m ² at the time of development, more preferably to be a 10mg / m ² ~150mg / m ² To adjust.

  By adjusting to the above range, a thermographic material having high sensitivity, low fog, and high maximum density is obtained. Examples of the solvent include those described in paragraph “0030” of JP-A No. 2001-264930. However, it is not limited to these. These solvents can be used alone or in combination of several kinds.

  In addition, content of the said solvent in thermographic material can be adjusted with conditions changes, such as temperature conditions in the drying process after an application | coating process. The content of the solvent can be measured by gas chromatography under conditions suitable for detecting the contained solvent.

(Packaging body)
When storing the thermographic material of the present invention, it is necessary to use a packaging material having a low oxygen permeability and / or moisture permeability in order to prevent changes in density and fogging over time, or to improve curling and curling. It is preferable to package. The oxygen permeability is preferably 50 ml / m ² or less per day at 25 ° C. and 1.01325 × 10 ⁵ Pa, more preferably 10 ml / m ² or less, and even more preferably 1.0 ml / m ² or less. . The moisture permeability is preferably 0.01 g / m ² · 40 ° C · 90% RH · day or less (according to JIS Z0208 cup method), more preferably 0.005 g / m ² · 40 ° C. · 90% RH · Day or less, more preferably 0.001 g / m ² · 40 ° C · 90% RH · day or less.

  Specific examples of the packaging material for the thermographic material include, for example, JP-A-8-254793, JP-A-2000-206653, JP-A-2000-235241, JP-A-2002-062625, JP-A-2003-015261. JP, JP 2003-057790, JP 2003-084397, JP 2003-098648, JP 2003-098635, JP 2003-107635, JP 2003-131337. JP-A-2003-146330, JP-A-2003-226439, JP-A-2003-228152, and the like.

  Further, the porosity in the package is 0.01% to 10%, preferably 0.02% to 5%. Nitrogen sealing is performed so that the nitrogen partial pressure in the package is 80% or more, preferably 90%. % Or better. The relative humidity in the package is preferably in the range of 10% RH to 60% RH, and more preferably 40% RH to 55% RH or less.

  Further, in the cutting process and the packaging process, in order to prevent image defects such as scratches and white spots, the cleanliness is US federal standard 209d class 10,000 as disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-341145. It is preferable to work in the following environment.

(Thermographic processing)
Thermographic imaging uses an infrared heat source in an analog fashion by direct exposure through the image or by reflection from the image, or preferably in the case of a substantially non-photosensitive thermographic material containing an infrared absorbing compound. By applying heat image-wise on a pixel-by-pixel basis, for example using an Nd-YAG laser or other infrared laser, or by direct thermal imaging using a thermal head.

In thermal printing, the image signal is converted into electrical pulses and then selectively transmitted to a thermal printhead via a driver circuit. Thermal printheads consist of microscopic heat resistor components that convert electrical energy into heat via the Joule effect. The operating temperature of a normal thermal print head is in the range of 300-400 ° C., the heating time per pixel can be less than 1.0 milliseconds, the pressurization of the thermal print head and the recording material The contact is, for example, 200 to 1000 g / linear cm, to ensure excellent heat transfer, ie a pressure of 5000 to 50,000 g / cm ² for a contact area (nip) of 200 to 300 μm.

  If the outermost layer on the same side as the thermal element of the support is not a protective layer, contact the image-wise heating of the recording material using the thermal printhead to avoid direct contact between the thermal printhead and this outermost layer. However, it can be removed through a resin sheet or web from which the recording material cannot transfer during heating.

  The activation of the heating component can be output-modulated or pulse-length modulated at a constant output. European Patent Application No. 654355 discloses an image forming method by image-wise heating using a thermal head having a heating component to which a voltage can be applied. In this method, activation of the heating component has a duty cycle ( duty cycled) in a pulsed manner. EP 622217 discloses an imaging method using a direct thermal imaging element that produces an improvement in continuous tone reproduction.

  The image-wise heating of the recording material can also be carried out using an electrically resistive ribbon introduced into the material. Image- or pattern-wise heating of the recording material can also be performed using ultrasonically modulated pixels.

(Industrial use)
Thermographic imaging for the creation of transparencies for use in reflective prints and especially in the medical diagnostic field where black-imaged transparencies are widely used in inspection methods operated using light boxes Can be used.

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

  Unless otherwise specified, “%” in the examples represents “mass%”.

Example 1
<< Preparation of undercoated photographic support >>
Corona of 8 W · min / m ² on both sides of a 175 μm thick polyethylene terephthalate film with an optical density of 0.150 (measured with a Densitometer PDA-65 manufactured by Konica Corporation) colored with the following blue dye and heat-fixed biaxially. The photographic support subjected to the discharge treatment was subjected to subbing. That is, the undercoat coating liquid a-1 was applied to one surface of this photographic support so that the dry film thickness was 0.2 μm at 22 ° C. and 100 m / min, and dried at 140 ° C. to form an image. A layer (image forming layer) side undercoat layer was formed (referred to as an undercoat underlayer A-1). Moreover, the following undercoat coating liquid b-1 was applied to the opposite surface as a backing layer undercoat layer at 22 ° C. and 100 m / min so that the dry film thickness was 0.12 μm, and dried at 140 ° C. An undercoat conductive layer having an antistatic function (referred to as undercoat underlayer B-1) was applied on the backing layer side. A corona discharge of 8 W · min / m ² is applied to the upper surfaces of the subbing lower layer A-1 and the subbing lower layer B-1, and the following subbing coating solution a-2 is dried on the lower subbing layer A-1. The film was coated at 33 ° C. and 100 m / min so as to have a film thickness of 0.03 μm, and dried at 140 ° C. to form an undercoat upper layer A-2. -2 was coated at 33 ° C. and 100 m / min to a dry film thickness of 0.2 μm, dried at 140 ° C. to form an undercoating upper layer B-2, and the support was further heat treated at 123 ° C. for 2 minutes. The sample was wound up under the conditions of 50 ° C. and 50% RH to prepare a subtracted sample.

[Preparation of aqueous polyester A-1 solution]
35.4 parts by weight of dimethyl terephthalate, 33.63 parts by weight of dimethyl isophthalate, 17.92 parts by weight of dimethyl sodium 5-sulfoisophthalate, 62 parts by weight of ethylene glycol, 0.065 parts by weight of calcium acetate / monohydrate, After transesterification of 0.022 parts by mass of manganese acetate tetrahydrate under a nitrogen stream while distilling off methanol at 170 to 220 ° C., 0.04 parts by mass of trimethyl phosphate and a polycondensation catalyst were used. 0.04 parts by mass of antimony oxide and 6.8 parts by mass of 1,4-cyclohexanedicarboxylic acid were added, and at a reaction temperature of 220 to 235 ° C., a theoretical amount of water was distilled off for esterification.

  Thereafter, the inside of the reaction system was further depressurized and heated over about 1 hour, and finally subjected to polycondensation at 280 ° C. and 133 Pa or less for about 1 hour to synthesize aqueous polyester A-1. The obtained aqueous polyester A-1 had an intrinsic viscosity of 0.33, an average particle size of 40 nm, and Mw = 80000 to 100,000.

  Next, 850 ml of pure water was placed in a 2 L three-necked flask equipped with a stirring blade, a reflux condenser, and a thermometer, and 150 g of aqueous polyester A-1 was gradually added while rotating the stirring blade. After stirring for 30 minutes at room temperature, the mixture was heated to an internal temperature of 98 ° C. over 1.5 hours and dissolved at this temperature for 3 hours. After completion of the heating, the mixture was cooled to room temperature over 1 hour and allowed to stand overnight to prepare a 15% by mass aqueous polyester A-1 solution.

[Preparation of Modified Aqueous Polyester B-1-2 Solution]
Into a 3 L four-necked flask equipped with a stirring blade, a reflux condenser, a thermometer and a dropping funnel, 1900 ml of the 15% by mass aqueous polyester A-1 solution was placed, and the internal temperature was adjusted to 80 ° C. while rotating the stirring blade. Until heated. Into this, 6.52 ml of a 24 mass% aqueous solution of ammonium peroxide was added, and a monomer mixture (28.5 g of glycidyl methacrylate, 21.4 g of ethyl acrylate, 21.4 g of methyl methacrylate) was dropped over 30 minutes. The reaction is continued for another 3 hours. Then, it cooled and filtered to 30 degrees C or less, and prepared the modified aqueous polyester B-1 solution (vinyl-type component modification | denaturation ratio 20 mass%) whose solid content concentration is 18 mass%.

  The solid content concentration was the same except that the vinyl modification ratio was 36% by mass and the modified components were styrene: glycidyl methacrylate: acetoacetoxyethyl methacrylate: n-butyl acrylate = 39.5: 40: 20: 0.5. An 18% by mass modified aqueous polyester B-2 solution (vinyl component modification ratio 20% by mass) was prepared.

[Production of Acrylic Polymer Latex C-1 to C-3]
Acrylic polymer latexes C-1 to C-3 having the monomer composition shown in Table 1 were synthesized by emulsion polymerization. The solid content concentration was 30% by mass.

[Image forming layer side undercoat coating solution a-1]
Acrylic polymer latex C-3 (solid content 30%) 70.0 g
Water dispersion of ethoxylated alcohol and ethylene homopolymer (solid content 10%) 5.0g
Surfactant (A) 0.1g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

<< Image Forming Layer Side Undercoat Layer Coating Solution a-2 >>
Modified aqueous polyester B-2 (18% by mass) 30.0 g
Surfactant (A) 0.1g
Spherical silica matting agent (Nippon Shokubai Co., Ltd. Sea Hoster KE-P50)
0.04g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

[Backing layer side undercoat coating solution b-1]
Acrylic polymer latex C-1 (solid content 30%) 30.0 g
Acrylic polymer latex C-2 (solid content 30%) 7.6 g
SnO ₂ sol 180.0g
(SnO ₂ sol synthesized by the method described in Example 1 of Japanese Patent Publication No. 35-6616 was heated and concentrated so that the solid content concentration was 10% by mass, and then adjusted to pH = 10 with ammonia water)
Surfactant (A) 0.5g
PVA-613 (PVA manufactured by Kuraray Co., Ltd.) 5% by weight aqueous solution 0.4 g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

[Backing layer side undercoat upper layer coating solution b-2]
Modified aqueous polyester B-1 (18% by mass) 145.0 g
Spherical silica matting agent (Nippon Shokubai Co., Ltd. Sea Hoster KE-P50)
0.2g
Surfactant (A) 0.1g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

  A backcoat layer and a backcoat layer protective layer having the following composition were coated on the undercoat layer B-2 of the support on which the undercoat layer had been applied.

<Preparation of backcoat layer coating solution>
While stirring 830 g of methyl ethyl ketone (MEK), 84.2 g of cellulose acetate propionate (manufactured by Eastman Chemical: CAP482-20) and 4.5 g of polyester resin (Bostic: VitelPE2200B) were added and dissolved. Next, 4.5 g of a fluorosurfactant (Asahi Glass Co., Ltd .: Surflon KH40) dissolved in 43.2 g of methanol and 2.3 g of a fluorosurfactant (Dainippon Ink Co., Ltd .: MegaFag F120K) were dissolved in the dissolved solution. Add and stir well until dissolved. Next, 2.5 g of oleyl oleate was added and stirred to prepare a backcoat layer coating solution.

<Preparation of backcoat layer protective layer (surface protective layer) coating solution>
The backcoat layer protective layer was also prepared in the same manner as the backcoat layer coating solution at the following composition ratio. Silica was dispersed in MEK at a concentration of 1% with a dissolver type homogenizer, and finally added.

Cellulose acetate propionate (10% MEK solution) 15.0 g
(Manufactured by Eastman Chemical: CAP482-20)
Monodispersed silica having a monodispersity of 15% (average particle size: 10 μm) 0.03 g
(Surface treatment with 1% aluminum of the total mass of silica)
C ₈ F ₁₇ (CH ₂ CH ₂ O) ₁₂ C ₈ F ₁₇ 0.075 g
Fluorine-based surfactant (SF-17) 0.01g
Fluoropolymer (FM-1) 0.05g
Stearic acid 0.1g
0.1 g butyl stearate
α-Alumina (Mohs hardness 9) 0.1g

<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 potassium 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 potassium solution. While maintaining the temperature of the above fatty acid potassium solution at 55 ° C., 450 ml of pure water was added and stirred for 5 minutes. Next, 468.4 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 with deionized water and drainage were 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). A powder organic silver salt A that has been dried and dried to a moisture content of 0.1% under the operating conditions (inlet 65 ° C., outlet 40 ° C.) of nitrogen gas atmosphere and dryer hot air temperature Got.

  In addition, the infrared moisture meter was used for the moisture content measurement of an organic silver salt composition.

<Preparation of preliminary dispersion A>
As a binder for an image forming layer (image forming layer), 14.57 g of SO ₃ K group-containing polyvinyl butyral (Tg 75 ° C., containing 0.2 mmol / g of —SO ₃ K group) was dissolved in 1457 g of MEK, and VMA-GETZMANN Preliminary dispersion A was prepared by gradually adding and thoroughly mixing the above-mentioned powdered organic silver salt A500 g while stirring with a dissolver DISPERMAT CA-40M type.

<Preparation of image forming layer dispersion A>
Media type disperser DISPERMAT filled with 80% of the internal volume of 0.5 mm diameter zirconia beads (Toray Industries, Inc .: Treceram) so that the residence time in the mill is 1.5 minutes using a pump. An image forming layer dispersion A 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 solution>
A stabilizer solution was prepared by dissolving 1.0 g of Stabilizer 1 and 0.31 g of potassium acetate in 4.97 g of methanol.

<Preparation of 2-chlorobenzoic acid solution>
1.488 g 2-chlorobenzoic acid, 2.779 g Stabilizer 2 and 365 mg 5-methyl-2-mercaptobenzimidazole are dissolved in 31.3 ml MEK in the dark to prepare a 2-chlorobenzoic acid solution did.

<Preparation of additive solution a>
Reducing agent (compound and amount described in Table 2), 0.159 g of yellow chromophoric leuco dye of general formula (YB) (compound described in Table 2), 0.159 g of cyan chromophoric leuco dye (in Table 2) Described compound), 1.54 g of 4-methylphthalic acid, was dissolved in 110.0 g of MEK to obtain an additive solution a.

<Preparation of additive liquid b>
1.56 g antifoggant 2, 0.5 g antifoggant 3, 0.5 g antifoggant 4, 0.5 g antifoggant 5, 3.43 g phthalazine dissolved in 40.9 g MEK and added b.

<Preparation of additive liquid c>
The silver saving agent (SE1-1) 0.05g was melt | dissolved in MEK39.95g, and it was set as the addition liquid c.

<Preparation of additive liquid d>
0.5 g of potassium p-toluenethiosulfonate and 0.5 g of antifoggant 6 were dissolved in 9.0 g of MEK to obtain an additive solution d.

<Preparation of additive liquid e>
An antifoggant containing 1.0 g of vinyl sulfone [(CH ₂ ═CH—SO ₂ CH ₂ ) ₂ CHOH] was dissolved in 9.0 g of MEK to obtain an additive solution e.

<Preparation of image forming layer coating solution>
In an inert gas atmosphere (nitrogen 97%), 50 g of the image-forming layer dispersion (described in Table 2) and 15.11 g of MEK were kept at 21 ° C. with stirring, and antifoggant 1 (10% methanol solution) 390 μl was added and stirred for 1 hour. Subsequently, 167 μl of a stabilizer solution was added and stirred for 10 minutes, and then 1.32 g of the 2-chlorobenzoic acid 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., 0.5 g of additive d, 0.5 g of additive e, and 13.31 g of binder used in preliminary dispersion A were added and stirred for 30 minutes, and then tetrachlorophthalic acid (9 .4% MEK solution) 1.084 g was added and stirred for 15 minutes. While further stirring, 12.43 g of additive liquid a, 1.6 ml of Desmodur N3300 / Movey aliphatic isocyanate (10% MEK solution), 4.27 g of additive liquid b, and 1.0 g of additive liquid c were added. By sequentially adding and stirring, an image forming layer coating solution was obtained.

  The chemical structures of the additives used for the preparation of each coating solution including the stabilizer solution and the image forming layer coating solution are shown below.

<Preparation of image forming layer protective layer lower layer (surface protective layer lower layer)>
Acetone 5g
MEK 21g
Cellulose acetate propionate 2.30g
(Manufactured by Eastman Chemical: CAP-141-20, glass transition temperature Tg = 190 ° C.)
7g of methanol
Phthalazine 0.25g
_{CH 2 = CHSO 2 CH 2 CH} 2 OCH 2 CH 2 SO 2 CH = CH 2 0.035g
C ₁₂ F ₂₅ (CH ₂ CH ₂ O) ₁₀ C ₁₂ F ₂₅ 0.01 g
Fluorine-based surfactant (SF-17) 0.01g
Stearic acid 0.10g
Butyl stearate 0.10g
α-Alumina (Mohs hardness 9) 0.10g
<Preparation of image forming layer protective layer upper layer (surface protective layer upper layer)>
Acetone 5g
21g of methyl ethyl ketone
Cellulose acetate propionate 2.3g
(Manufactured by Eastman Chemical: CAP-141-20 glass transition temperature Tg = 190 ° C.)
Paraloid A-21 (Rohm and Haas) 0.08g
Benzotriazole 0.03g
7.00g of methanol
Phthalazine 0.25g
Monodispersed 15% monodispersed silica (average particle size: 3 μm) 0.140 g
(Surface treatment with 1% by mass of aluminum based on the total mass of silica)
_{CH 2 = CHSO 2 CH 2 CH} 2 OCH 2 CH 2 SO 2 CH = CH 2 0.035g
C ₁₂ F ₂₅ (CH ₂ CH ₂ O) ₁₀ C ₁₂ F ₂₅ 0.01 g
Fluorosurfactant (SF-17) 0.005g
Fluorine polymer (FM-1) 0.01g
Stearic acid 0.10g
Butyl stearate 0.10g
α-Alumina (Mohs hardness 9) 0.10g
The upper layer and the lower layer of the image forming layer protective layer were formed by the same method as the preparation of the backcoat layer coating solution at the above composition ratio. As for the silica, similarly to the backcoat layer protective layer, MEK was dispersed with a dissolver type homogenizer at a concentration of 1% by mass, and finally added and stirred to obtain a coating solution for the upper and lower layers of the image forming layer protective layer. .

<Preparation of thermographic material>
The backcoat layer coating solution and the backcoat layer protective layer coating solution prepared as described above were extruded onto the undercoating upper layer B-2 so as to have a dry film thickness of 1.5 μm, respectively. Application was performed in minutes. The drying was performed for 5 minutes using a drying air having a drying temperature of 100 ° C. and a dew point temperature of 10 ° C.

  The image forming layer coating solution and the image forming layer protective layer (surface protective layer) coating solution are simultaneously coated on the subbing upper layer A-2 at an application speed of 50 m / min using an extrusion coater. The thermographic material samples 101 to 114 shown in Table 2 were prepared. Application is a dry film thickness of 10.5 μm for the image forming layer, and an image forming layer protective layer (surface protective layer) is 3.0 μm in dry film thickness (surface protective layer upper layer 1.5 μm, surface protective layer lower layer 1.5 μm). Then, 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.

  The obtained thermographic material (101 to 114) had a Beck smoothness of 6000 seconds on the image forming layer side surface, and a Beck smoothness of the backcoat layer side surface of 9000 seconds. Moreover, when the surface roughness was measured about the samples 101-114, they were Rz (E) / Rz (B) = 0.40 and Rz (E) = 1.4 micrometers.

  Rz (B) was 3.5 μm. Ra (E) was 0.09 μm. Ra (B) was 0.12 μm. Regarding samples 101 to 112, an absorption peak at a maximum absorption wavelength of 420 nm due to the yellow coloring leuco dye was observed.

  In addition, with respect to Samples 101 to 106, 109 to 111, and 113, absorption peaks having a maximum absorption wavelength of 640 nm due to the cyan coloring leuco dye were observed. In addition, an absorption peak at a maximum absorption wavelength of 620 nm due to the cyan color-forming leuco dye was observed for Samples 107 to 108.

  For sample 109, in the preparation of powdered organic silver salt A in sample 103, instead of behenic acid 130.8 g, arachidic acid 67.7 g, stearic acid 43.6 g, and palmitic acid 2.3 g, behenic acid 259. Sample 109 was prepared in the same manner as Sample 103 except that 4 g and arachidic acid 0.5 g were used.

Sample 110 was the same as Sample 103 except that the fluorine-based activator of the backcoat layer protective layer and the image forming layer protective layer (upper layer and lower layer) in Sample 103 was changed from SF-17 to C ₈ F ₁₇ SO ₃ Li. Thus, a sample 110 was produced.

For sample 111, SO ₃ K group-containing polyvinyl butyral (Tg 75 ° C., containing 0.2 mmol / g SO ₃ K) was used as the image-forming layer binder in the preparation of preliminary dispersion A in sample 103. Sample 111 was produced in the same manner as Sample 103, except that ₃ K group-containing polyvinyl butyral (Tg 65 ° C., SO ₃ K contained 0.2 mmol / g) was used.

<Thermographic printing>
Substantially non-photosensitive thermographic material samples 101-114 made as described above were printed at 14 mm / sec and a line-time of 3.5 milliseconds instead of 7.1 milliseconds. 508 dpi (dpi is 2.54 cm per inch), modified to operate at 75 μm length (in the transport direction) and 50 μm wide thermal head resistors are output-modulated to produce various image densities Printed on a DRYSTAR ^™ 4500 printer from AGFA-GEVAERT having a resolution of.

(Packaging material)
PET 10 μm / PE 12 μm / Aluminum foil 9 μm / Ny 15 μm / Polyethylene 50% containing carbon 3%, oxygen permeability: 0.02 ml / m ² per day at 25 ° C. and 1.01325 × 10 ⁵ Pa, moisture permeability: 0.001 g / Barrier bag of m ² · 40 ° C · 90% RH · day (according to JIS Z0208 cup method).

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

<Image density>
The maximum density (D _max ) of the image measured through a visible filter was measured using a MACBETH ^™ TR924 densitometer.

《Fog》
The minimum density (D _min ) of the image measured through a visible filter was measured using a MACBETH ^™ TR924 densitometer.

《Silver tone》
A chest X-ray image was baked on each heat-development thermographic material sample, and the silver color after processing was visually evaluated using a Schaukasten. A wet-processed laser imager film manufactured by Konica Minolta Co., Ltd. was used as a standard sample at this time, and the color tone relative to the standard sample was visually evaluated by 0.5 increments according to the following criteria.

5: The same color tone as the standard sample 4: Almost the same preferred color tone as the standard sample 3: Level slightly different from the standard sample, but practically no problem 2: Color tone clearly different from the standard sample 1: Unpleasant color tone different from the standard sample << Light Irradiation Image Preservability >>
Each thermographic material sample was heat-developed in the same manner as described above, and the change in the image after standing for 10 days after being pasted on a 1000 lux Schaukasten was visually evaluated in 0.5 increments according to the following criteria. .

5: Almost no change 4: Slight color change observed 3: Partial color change and fog increase observed 2: Color change and fog increase observed in considerable part 1: Color change and fog increase The increase is remarkable and strong density unevenness occurs on the entire surface.
Evaluation of raw storage stability was made by storing the image recording material as it was packed in the packaging material before heat development for 10 days under conditions of 50 ° C. and 40% relative humidity, and then opening it again at 25 ° C. and 40% relative humidity. Thermal development was performed, and thermal development was performed at 25 ° C. and a relative humidity of 40% before storage, and the density change (ΔDmin) of the white background before and after storage was measured.

  The results are also shown in Table 2.

  From Table 2, the sample of the present invention has a light irradiation image storability and a raw storability even when it is rapidly developed with a small thermal printer or diagnosed with a high illuminance Shakasten compared to the comparative sample. It is clear that it has excellent properties, low fog, and excellent silver tone.

  Further, comparing Samples 111 and 103, it was found that Sample 103 had better characteristics with respect to fog increase during high-temperature storage.

Claims (5)

It has an image forming layer containing an organic silver salt, a binder and a reducing agent on a support, and the image forming layer contains a leuco dye that forms a dye image by color development during heat development. A substantially non-photosensitive black and white monosheet thermographic recording material. 2. The substantially non-photosensitive black and white monosheet thermographic recording material according to claim 1, wherein at least one of the maximum absorption wavelengths of the dye image is in a range of 360 nm to 450 nm. The substantially non-photosensitive black and white monosheet thermographic recording material according to claim 1 or 2, wherein at least one of the maximum absorption wavelengths of the dye image is in the range of 600 nm to 700 nm. 4. The substantially non-photosensitive material according to claim 1, wherein the addition ratio of the leuco dye to the sum of the reducing agents is 0.001 to 0.2 in terms of molar ratio. Black-and-white monosheet thermography recording material. The substantially non-photosensitive black and white monosheet thermographic recording material according to any one of claims 1 to 4, comprising a compound represented by the following general formula (SF).
General formula (SF)
(R _f − (L ₁ ) _m1 −) _p − (Y) _n1 − (A) _q
[Wherein R _f represents a substituent containing a fluorine atom, L ₁ represents a divalent linking group having no fluorine atom, and Y represents a (p + q) -valent linking group having no fluorine atom. , A represents an anionic group or a salt thereof, m1 and n1 each represents an integer of 0 or 1, p represents an integer of 1 to 3, and q represents an integer of 1 to 3. However, when q is 1, m1 and n1 are not 0 at the same time. ]