JP2003075955A - Photothermographic imaging material with improved silver tone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photothermographic imaging material having high sensitivity and low fog, improving silver tone and less liable to scuffing because of high film strength. SOLUTION: In the photothermographic imaging material comprising photosensitive silver halide grains, an organic silver salt, a reducer for the organic silver salt and a binder on a support, at least one star burst molecular compound of the formula A1 -(B1 )n1 -(B2 )n2 -(B3 )n3 -...-(Bn )nn is contained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a photothermographic image forming material, and more particularly to a photothermographic image forming material having excellent scratch resistance.

[0002]

2. Description of the Related Art In recent years, a photothermographic material that does not produce waste liquid associated with a wet process has been strongly desired in the fields of medical treatment and printing from the viewpoint of environmental protection and workability. Technologies relating to photothermographic materials capable of forming images and used in photographic technology have been commercialized and rapidly spread. Since these photothermographic materials are usually developed at a temperature of 80 to 140 ° C., they are called photothermographic image forming materials, which are distinguished from conventional photosensitive materials which are liquid-developed in the range of 25 to 45 ° C. There is.

This type of photothermographic image-forming material has hitherto been irradiated to a photosensitive layer containing a highly sensitive silver halide grain spectrally sensitized with a dye, an organic silver salt and a reducing agent, and the photosensitive layer. It is composed of an antihalation layer (AH layer) which prevents light from passing through without being absorbed and being reflected by an interface of the support, an intermediate layer or an adhesive layer, or a backing layer (BC layer) provided on the opposite side of the support. Further, a protective layer for preventing scratches during handling is provided on the photosensitive layer and the BC layer.

In general, a photothermographic image-forming material is a physical development in which fine silver halide is used as a physical development nucleus while precipitating silver ions from an organic silver salt, so that the developed silver has a yellow color tone after development. As it is easy to use, we use a toning agent to make it black. The toning agent has a property of adsorbing silver halide and organic silver, and controls the growth of the silver filament during development to prevent the color tone from changing to a yellow tone. A preferable performance as a color tone agent is that the color tone can be changed to black tone or cold black tone without deteriorating photographic sensitivity and storability. Phthalazine compounds in photothermographic image-forming materials are commonly used as a compound capable of promoting development to enhance sensitivity and making developed silver a black tone, but nano-sized silver halide fine particles are iridium, rhodium or Dope of noble metal atoms such as ruthenium and spectral sensitizing dyes cause silver tone to deteriorate when highly sensitized.
There is a need for good additives that do not degrade the silver tone.

In addition to phthalazine, the use of polyhalomethane compounds is disclosed in JP-A-63-40611, JP-A-59-57234 and JP-A-59-90842.
And Japanese Patent Application Laid-Open No. 2001-171063. However, in all cases, the polyhalomethane compound aims at the effect as a photofogging inhibitor, and does not aim at improving the silver tone. With polyhalomethane compounds, the effect of improving the silver tone is not sufficient, and it is difficult to obtain high sensitivity. A disulfide compound is generally used as an antifoggant, but has a small effect of improving the silver color tone. The compounds described above control the growth of filaments of developed silver by the action of silver halide grains or silver ions electrostatically or by binding as a ligand of a complex, hydrogen bonding or the like. As another method of controlling the growth of the silver filament, there is a method of adjusting the film of the photosensitive layer or the film of a layer adjacent to the photosensitive layer with a crosslinking agent. A cross-linking agent may be used to suppress the growth of the developed silver filament in order to make the silver color tone a cold black tone, but there is a problem that depending on the type of the cross-linking agent, the yellowness increases and the transparency is impaired. The color turbidity due to the cross-linking agent is because the cross-linking agent reacts with other additives to generate a new bonding group, and the group absorbs visible light spectroscopically. Aldehyde-based cross-linking agents and aziridine-based cross-linking agents often cause visible absorption and cause color turbidity (residual color).

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photothermographic image-forming material which has high sensitivity and low fog in photographic performance, has improved silver tone and is excellent in scratch resistance.

[0007]

The above objects of the present invention have been achieved by the following constitutions.

1. Photosensitive silver halide grains on a support,
A photothermographic image-forming material containing an organic silver salt, a reducing agent and a binder for the organic silver salt, containing at least one starburst molecular compound represented by the general formula (1). Photographic material.

2. 2. The photothermographic image-forming material as described in 1 above, which contains at least one starburst molecular compound in the photosensitive layer or a layer adjacent to the photosensitive layer.

3. 2. The photothermographic image-forming material as described in 1 above, which contains at least one phthalazine compound represented by the general formula (2).

4. 2. The photothermographic image-forming material as described in 1 above, wherein the photosensitive layer or a layer adjacent to the photosensitive layer contains at least one mercapto compound represented by the general formula (3).

5. 2. The photothermographic image-forming material as described in 1 above, wherein the photosensitive layer or a layer adjacent to the photosensitive layer contains at least one disulfide compound represented by the general formula (4).

6. 2. The photothermographic image forming material as described in 1 above, wherein at least one kind of the reducing agent represented by the general formula (5) is contained in the photosensitive layer or a layer adjacent to the photosensitive layer.

7. 2. The photothermographic image-forming material as described in 1 above, wherein the binder is crosslinked with at least one crosslinking agent selected from an isocyanate compound, a vinylsulfonyl compound, an epoxy compound and an alkoxysilane compound.

The present invention will be described in more detail. The “starburst molecular compound” used in the present invention is a molecule or atom in which three or more same or different kinds of molecules or groups of atoms are bonded to a central atom or a group of central atoms, and the same kind or different kinds of molecules or atoms are further added to the molecule or group of atoms. It is a compound in which a group repeats bonding and the atomic group spreads in a star shape to form a molecule. These compounds are chemical letters (Chemical Let)
ter), 1989, pages 1145 and 1991.
Defined on page 1731 of the year. Such molecules are also called dendrimers (resin-like molecules). The first atomic group generated by the first chemical bond to the central atom or molecule
It is called a generational molecule, and a molecule in which atomic groups are propagated so as to spread like a star in the second generation is called a second generation molecule. The number of generations can be increased (proliferation) by sequentially spreading the molecules in concentric circles. Preferred starburst molecular compounds for the present invention include first generation molecules up to at most 100,000 generation molecules. The propagation of generations may be performed by condensation polymerization, addition polymerization, ionic polymerization, coordination polymerization, or radical polymerization method in addition to the sequential reaction. Polymerization growth can be grown to levels of thousands to tens of thousands at a time. The growth up to the middle may be carried out by a sequential reaction, and thereafter the growth may be carried out by a combination of polymerization methods and the like. Normally, the second to twentieth generations are used.

When the atom is placed at the center, nitrogen, phosphorus, aluminum, boron, zinc, tin, silicon, iridium, rhodium, palladium, scandium, praseodymium, ruthenium, iron and the like have a valence of 3 or more and 6 or less. Atoms are preferred. Particularly preferred atoms are nitrogen atom, phosphorus atom or boron atom.

When the molecule is placed at the center, various polyfunctional molecules can be mentioned. For example, pigment molecules, dyes,
There are silver tone improving agents, antifoggants, anti-printing agents, ultraviolet absorbers, crosslinking agents, development accelerators and developers.

The starburst molecular compound preferred in the present invention is also a "starburst molecular compound having π electrons" because it has one or more π electrons in the molecule. Since the starburst molecular compound can proliferate three-dimensionally, it can have a structure of molecular sphere and can be present in the photothermographic image-forming material of the present invention in a nano-sized molecular sphere state. Functional molecules in the center (UV absorber, visible light absorber, infrared absorber, radical releasing agent, adsorbent,
The method of providing a development accelerator, a developer, an antifoggant, etc.) controls the reaction of the functional molecule, and thus obtains favorable photographic performance. Even when the above-mentioned functional molecule is not provided, the orientation, viscoelasticity, glass transition point, melting point, etc. of the molecule interact with the binder or additive of the layer of the photothermographic image forming material to improve developability and storability. Can be improved.
The usual addition, condensation, polymerization reaction and the like can be referred to for the synthesis method of these compounds.

In the starburst molecular compound represented by the general formula (1), A ₁ , B ₁ , B ₂ , B ₃ and B _n are 3
A hexavalent atom (for example, nitrogen, phosphorus, boron, aluminum, zinc, tin, silicon, gallium, iron, scandium, praseodymium, rhodium, iridium, ruthenium, platinum, palladium) or a ring (for example, triazine ring,
Phosphazene ring, porphyrin ring, phthalocyanine ring,
A benzene ring or a pyridine ring). The aromatic ring or hetero ring may have a substituent on the ring, and the substituent includes an alkyl group (eg, methyl group, ethyl group and hexyl group), an alkoxy group (eg, methoxy group, ethyloxy group and Hexyloxy group, etc.), hydroxy group, cyano group, halogen atom (eg, chlorine atom, fluorine atom, bromine atom, etc.) and the like. Or functional molecule (absorbs or absorbs ultraviolet rays, visible rays, infrared rays, etc.)
A group of atoms forming n1 represents a positive integer of 3 to 6, n2 and n3 to nn represent positive integers of 2 to 6. Preferred starburst molecular compounds are shown below.

[0020]

[Chemical 6]

[0021]

[Chemical 7]

[0022]

[Chemical 8]

[0023]

[Chemical 9]

[0024]

[Chemical 10]

[0025]

[Chemical 11]

[0026]

[Chemical 12]

[0027]

[Chemical 13]

[0028]

[Chemical 14]

The starburst molecular compound of the present invention can be added to the coating solution by a known addition method. That is, it can be added by dissolving it in alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone and acetone, polar solvents such as dimethyl sulfoxide and dimethylformamide, and the like.

Fine particles may be dispersed in water or an organic solvent without being dissolved in water or a solvent to which the starburst molecular compound of the present invention is added. To disperse the fine particles, the starburst molecular compound of the present invention is subjected to sand mill dispersion using glass beads or zirconia fine particle media, the solution is jetted at high speed from a narrow tube to crush it on a hard plate, or a liquid of a thin tube from two directions is used. Any of the methods of colliding and dispersing may be used. Fine particles are dispersed in an aqueous solution with an average particle size of 1 nm or more 1
The size is preferably 0 μm or less, and the particle distribution is preferably narrow. In order to disperse in an aqueous solution, it is preferable that bubbles are less likely to be generated by stirring.

The starburst molecular compound of the present invention is preferably added to a layer in which an additive such as a silver halide, an organic silver salt and a reducing agent is present and a layer adjacent to the layer.

The addition amount of the starburst molecular compound represented by the general formula (1) of the present invention is preferably 1 × 10 ^-8 to 1 × 10 ^-1 mol, and particularly 1 × 10 ^-5 to 1 per mol of silver. × 1
It is 0 ^-2 mol. Even when it is added to a layer other than the silver-free photosensitive layer, the addition amount can be determined by converting it into a unit area. If the addition amount is large, the sensitivity is lowered, the contrast is lowered, the maximum density is lowered, and the like. If the addition amount is insufficient, it is difficult to obtain the silver tone improving effect of the present invention.

Phthalazine compound represented by the general formula (2)
Where R₃, R_Four, R_Five, R₆, R ₇And R₈Is that
Hydrogen atom, halogen atom, cyano group, hydroxy group,
Amino groups, sulfonic acid groups and their salts (eg sulfonic acid
Sodium, Potassium Sulfonate and Lithium Sulfonate
Um, etc.), carboxylic acid groups and salts thereof (eg carboxylic acid
Sodium, potassium carboxylate, lithium carboxylate
Etc.), phosphate groups and their salts (eg sodium phosphate, phosphoric acid
Potassium and lithium phosphate, etc.), C1-20 al
Kill group (eg, methyl group, ethyl group, butyl group, octyl group
Tyl group and dodecyl group, etc., alkenyl group (eg,
Propenyl group, butenyl group and butadienyl group, etc.),
Alkoxy groups (eg methoxy, ethoxy and
Dodecyloxy group, etc.), 5-membered or 6-membered fragrance, respectively
Group groups (eg, phenyl and naphthyl groups) and
Heterocycle (eg, pyridyl group, imidazolyl group, tricycle
Azolyl group and oxazolyl group). Phthalazi
The method of using the compound is the starburst molecularization of the present invention.
A method similar to that of compound can be adopted. General below
A preferred specific example represented by formula (2) is shown.

[0034]

[Chemical 15]

In the mercapto compound represented by the general formula (3) of the present invention, W ₁ represents an NH group, an oxygen atom, a sulfur atom and a CH ₂ group, and Q is a 6-membered optionally substituted group. Aromatic ring groups (eg phenyl and naphthyl groups)
And a substituent on the ring Q is a hydrogen atom, a halogen atom,
Cyano group, hydroxy group, amino group, sulfonic acid group and salts thereof (eg sodium sulfonate and potassium sulfonate), carboxylic acid group and salts thereof (eg sodium carboxylate and potassium carboxylate), phosphoric acid group Salts thereof (for example, sodium phosphate and potassium phosphate), alkyl groups having 1 to 20 carbon atoms (for example, methyl group,
An ethyl group, a propyl group and an octyl group), an alkenyl group (eg a pentadienyl group and an isobutenyl group), a 5- or 6-membered aromatic group (eg a phenyl group and a naphthyl group) and a heterocyclic group (eg, Pyridyl group, triazolyl group, imidazolyl group, oxazolyl group and the like). L ₂ is a divalent linking group (eg, ethylene group, butylene group, isobutylene group, phenylene group, sulfonyl group, sulfinyl group, etc.), M is an alkali metal atom (eg, sodium, potassium, lithium, etc.), NH ₄ Represents a group of atoms or a hydrogen atom. p is 0
Or represents 1. Preferred mercapto compounds represented by the general formula (3) of the present invention are shown below.

[0036]

[Chemical 16]

The method of use is the same as that of the starburst molecular compound of the present invention. In the disulfide compound represented by the general formula (4) of the present invention, Y ₁ and Y ₂ each may have a substituent, and are a 5- or 6-membered aromatic ring group (for example, a phenyl group and a naphthyl group). Etc.) or a heterocyclic group (for example, a pyridyl group, a pyrimidyl group, a furyl group and a thiophenyl group), and a substituent on the ring is a hydrogen atom, a halogen atom, a cyano group, a hydroxy group, an amino group or a sulfonic acid group. Salts thereof (eg, lithium sulfonate and sodium sulfonate), carboxylic acid groups and salts thereof (eg sodium carboxylate and lithium carboxylate), phosphoric acid groups and salts thereof (eg sodium phosphate and potassium phosphate), An alkyl group having 1 to 20 carbon atoms (for example, a methyl group, an ethyl group, an octyl group, a dodecyl group, an octodecyl group, etc.), an alkeny Group (eg, propenyl group, pentadiene group, etc.), 5- or 6-membered aromatic group (eg, phenyl group, naphthyl group, etc.) or heterocyclic group (eg, pyridyl group, piperidyl group, pyrimidyl group, thiophenyl group) And a furyl group). Preferred specific examples of the disulfide compound represented by the general formula (4) of the present invention are shown below.

[0038]

[Chemical 17]

The method of using the disulfide compound of the present invention can be the same as that of the starburst molecular compound of the present invention.

In the reducing agent represented by the general formula (5) of the present invention, R'and R "are each an optionally substituted alkyl group having 1 to 25 carbon atoms (eg, methyl group, ethyl group). , Octyl group, dodecyl group and hexadecyl group), alkenyl group (eg propenyl group and pentadienyl group) or cycloalkyl group (eg 1-
A methylcycloalkyl group, a 1-cyclopentyl group, a 4-methylcyclohexyl group and the like), L ₃ is a divalent linking group (for example, a methylene group, an ethylene group, a phenylene group, a cyclohexylene group, a bond of a cyclohexylene group and an alkylene group) Body etc.). At least one of the substituents is particularly preferably a cyclohexyl group or a 1-methylcyclohexyl group. Preferred specific examples of the reducing agent represented by the general formula (5) of the present invention are shown below.

[0041]

[Chemical 18]

The method of using the reducing agent represented by the general formula (5) of the present invention can be the same as that of the starburst molecular compound of the present invention.

Preferred binders used in the present invention are gelatin, cellulose derivatives, polyvinyl alcohol derivatives (including polyacetal), methacrylate polymer derivatives, vinyl acetate derivatives, acrylate polymer derivatives, polyimide derivatives, polyamide derivatives, phenol resin derivatives, Examples include urethane resin derivatives and polyester derivatives. A particularly preferred derivative is a polyvinyl alcohol derivative or a vinyl acetate derivative.

When the binder is used alone to form a film, it can maintain the adhesion to the lower layer and the upper layer and obtain a film strength that is not easily scratched. However, the use of a crosslinking agent further enhances the film adhesion. be able to. However, if the crosslinking reaction is slow, the photographic performance is not stable and the storage stability is deteriorated. The fast-acting, preferred crosslinking agent used in the present invention is an isocyanate group,
Examples thereof include a polyfunctional crosslinking agent having at least two epoxy groups or vinylsulfonyl groups, or an alkoxysilane compound having at least one alkoxysilane group. Preferred crosslinking agents are shown below.

H1 hexamethylene diisocyanate H2 hexamethylene diisocyanate trimer H3 Tolylene Diisocyanate H4 phenylene diisocyanate H5 xylylene diisocyanate

[0046]

[Chemical 19]

The above-mentioned cross-linking agent may be dissolved in water, alcohols, ketones or non-polar organic solvents and added,
It may be added as a solid to the coating solution. The addition amount is preferably equivalent to the crosslinkable group of the binder, but may be increased up to 10 times or may be decreased up to 1/10 or less. If the amount is too small, the crosslinking reaction will not proceed, and if it is too large, the unreacted crosslinking agent deteriorates the photographic properties, which is not preferable.

The photosensitive silver halide used in the photothermographic image-forming material of the present invention can be prepared by a method known in the photographic art such as a single jet method or a double jet method, for example, an ammonia method emulsion, a neutral method, It can be prepared by any method such as an acidic method.

The silver halide is preferably one having a small grain size in order to suppress white turbidity (haze) after image formation and to obtain a good image quality. 10 in average particle size
0 nm or less, preferably 10 nm to 60 nm, especially 20
nm to 50 nm is preferable. The shape of the silver halide is not particularly limited, and it may be cubic or octahedral so-called normal crystal or non-normal crystal spherical, rod-shaped or tabular grain. The silver halide composition is also not particularly limited and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide and silver iodide.

The amount of silver halide is 50% or less, preferably 25% to the total amount of silver halide and organic silver salts described below.
It is 0.1%, more preferably between 15% and 0.1%.

The photosensitive silver halide used in the photothermographic imaging element of this invention is also described in British Patent No. 1,447,4.
As described in Japanese Patent No. 54, when a halogen component such as a halide ion is made to coexist with an organic silver salt-forming component when an organic silver salt is prepared, and silver ions are injected into the component to form an organic silver salt. It can be generated almost simultaneously.

As still another method, a silver halide-forming component is allowed to act on a previously prepared solution or dispersion of an organic silver salt or a sheet material containing the organic silver salt to expose a part of the organic silver salt to light. It can also be converted into a polar silver halide.
The silver halide thus formed is in effective contact with the organic silver salt and exhibits a preferable effect.

These photosensitive silver halides include metals belonging to Groups 6 to 11 of the Periodic Table of the Elements, such as Rh, Ru, Re, Ir, Os, and F, for illuminance failure and gradation adjustment.
Doping (containing) ions such as e, their complexes or complex ions
Can be made. These metal ions may be introduced into the silver halide as a metal salt as they are, but can be introduced into the silver halide in the form of a metal complex or a complex ion. As these transition metal complex and metal complex ion, a hexacoordinated complex ion is preferable.

Specific examples of the ligand include halogen, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aco ligands, nitrosyl, thionitrosyl and the like, preferably aco, nitrosyl and Thionitrosyl and the like. When an aco ligand is present, it preferably occupies one or two of the ligands.

Specific examples of particularly preferred doped metal atoms are:
Rhodium (Rh), Ruthenium (Ru), Rhenium (R
e), iridium (Ir) and osmium (Os).

One kind of these metal complexes or complex ions may be used, or two or more kinds of the same metal and different kinds of metals may be used in combination.

The content of these metal ions, metal complexes and complex ions is generally 1 × 10 ^-9 to 1 × 10 ^-2 mol, preferably 1 mol, per mol of silver halide. It is x10 ^-8 to 1 x 10 ^-4 mol. An excessive amount of addition causes a decrease in sensitivity, a soft tone, and a decrease in maximum density, which is not preferable. A compound providing an ion or a complex ion of these metals is preferably added at the time of silver halide grain formation and incorporated into the silver halide grain. Preparation of the silver halide grain, that is, nucleation, growth and physical ripening. , It may be added at any stage before and after the chemical sensitization, but it is particularly preferable to add it at the stage of nucleation, growth and physical ripening, more preferably at the stage of nucleation and growth. It is preferably added at the stage of nucleation. Upon addition, it may be added in several divided portions, or it may be added uniformly in the silver halide grains, or in JP-A-63-29603, JP-A-2-306236 and JP-A-2-306236.
-167545, 4-76534, 6-110
As described in JP-A No. 146, JP-A No. 5-273683, etc., the particles can be contained with a distribution.

These metal compounds can be added after being dissolved in water or a suitable organic solvent (eg alcohols, ethers, glycols, ketones, esters, amides). A method of adding an aqueous solution of the powder of (1) or an aqueous solution of a metal compound and NaCl, KCl together to a water-soluble silver salt solution or a water-soluble halide solution during grain formation, or a silver salt solution and a halide solution. When mixed at the same time, it is added as a third aqueous solution to prepare silver halide grains by a three-liquid simultaneous mixing method, a method in which a necessary amount of an aqueous solution of a metal compound is charged into a reaction vessel during grain formation, or a halogen There is a method of adding and dissolving another silver halide grain which is previously doped with a metal ion or a complex ion at the time of preparing silver halide.

The photosensitive silver halide prepared by the above-mentioned various methods includes, for example, sulfur-containing compounds, gold compounds,
Chemical sensitization can be performed with a platinum compound, a palladium compound, or a combination thereof. For the method and procedure for this chemical sensitization, see US Pat. No. 4,036,6.
50, British Patent Nos. 1,518,850, JP-A-51-22430, JP-A-51-78319, and JP-A-51-78319.
No. 1-81124.

In the present invention, a matting agent is preferably contained on the photosensitive layer side, and a matting agent is preferably arranged on the surface of the photosensitive material in order to prevent scratching of the image after heat development. Is preferably contained in an amount of 0.5 to 30% with respect to the total binder on the photosensitive layer side.

When a non-photosensitive layer is provided on the side opposite to the photosensitive layer with a support sandwiched between them, it is preferable to include a matting agent in at least one layer on the non-photosensitive layer side so as to improve the slip property of the photosensitive material and the adhesion of fingerprints. For prevention, it is preferable to dispose a matting agent on the surface of the light-sensitive material, and the matting agent is 0.5 to 40% by mass with respect to the total binder in the layer on the side opposite to the light-sensitive layer side.
It is preferable to contain.

The material of the matting agent used in the present invention may be either an organic substance or an inorganic substance. For example, as the inorganic substance, silica described in Swiss Patent No. 330,158 and the like, and as the organic substance, US Pat. No. 2,322,03
No. 7, etc., starch derivatives, such as Belgian Patent No. 625,451 and British Patent No. 981,198, polyvinyl alcohols described in Japanese Patent Publication No. 44-3643, Swiss Patent No. 330,158. Or polymethacrylate described in U.S. Pat.
Organic matting agents such as polyacrylonitrile described in US Pat. No. 079,257 and polycarbonate described in US Pat. No. 3,022,169 can be used.

The shape of the matting agent may be either a fixed shape or an amorphous shape, but a fixed shape is preferable, and a spherical shape is preferably used. The size of the matting agent is represented by the diameter when the volume of the matting agent is converted into a spherical shape. In the present invention, the particle size of the matting agent refers to the spherically converted diameter.

The matting agent used in the present invention preferably has an average particle size of 0.5 μm to 10 μm, more preferably 1.0 μm to 8.0 μm. The coefficient of variation of particle size distribution ((standard deviation of particle diameter) / (average value of particle diameter) × 100) is preferably 50% or less, more preferably 40% or less, and particularly preferably The matting agent is preferably 30% or less.

The method for adding the matting agent according to the present invention may be a method in which the matting agent is preliminarily dispersed in a coating solution and then coated.
A method of spraying the matting agent after applying the coating solution and before the completion of drying may be used. When adding a plurality of types of matting agents, both methods may be used in combination. The amount of the matting agent added can be appropriately determined at a level at which haze does not become a problem depending on the size of the matting particles.
It is preferable to use 0.01 mg / m ^{2 to 1} g / m ² . If added excessively, haze becomes a problem.

As the support, a support such as polyethylene terephthalate, polyethylene naphthalate or syndiotactic polystyrene is preferable, and biaxially stretched or heat-fixed has high optical isotropy and good dimensional stability.
It is preferable that the thickness is from μm to 400 μm.

As the exposure method, Japanese Patent Laid-Open No. 9-30486
No. 9, No. 9-311403, and Japanese Patent Laid-Open No. 2000-2000.
Laser exposure can be carried out by the method described in Japanese Patent No. 10230. For exposure of the photothermographic image forming material of the present invention, it is desirable to use a light source suitable for the color sensitivity imparted to the photosensitive material. For example, when the sensitive material is made to be sensitive to infrared light, it can be applied to any light source in the infrared light range, but the laser power is high and the photosensitive material can be transparent. From the above points, the infrared semiconductor laser (780 nm, 820 nm) is more preferably used.

An apparatus for developing a photothermographic image forming material is
JP-A No. 11-65067 and 11-72897.
No. 11-84619 and No. 11-84619 can be used.

[0069]

EXAMPLES The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1 Preparation of undercoated photographic support Commercially available biaxial stretching heat colored blue to 0.170 with optical density
Fixed 175 μm thick polyethylene terephthalate
Corona discharge treatment (8W / m ²・ Minute)
Apply the undercoat coating solution a-1 below on one side and dry.
Dried to form the undercoat layer A-1, and on the opposite surface,
Coating solution b-1 is applied and dried to undercoat the back layer side.
It was designated as Layer B-1.

Undercoat coating liquid a-1 Butyl acrylate (30% by mass) t-Butyl acrylate (20% by mass) Styrene (25% by mass) 2-Hydroxyethyl acrylate (25% by mass) Copolymer latex liquid (solid content 30%) 0.08 g / m ² hexamethylene-1,6-bis (ethylene urea) 0.008 g / m ² undercoat coating liquid b-1 butyl acrylate (40 mass%) styrene (20 mass%) glycidyl acrylate (40 (% By mass) copolymer latex liquid (solid content 30%) 0.08 g / m ² hexamethylene-1,6-bis (ethylene urea) 0.008 g / m ² subsequently, undercoat layer A-1 and undercoat layer B -1 is subjected to corona discharge of 8 W / m ² · min, and the undercoat layer A-
The following undercoating upper layer coating liquid a-2 was coated on 1 as the undercoating upper layer A-2 to a dry film thickness of 0.1 μm,
On the undercoat layer B-1, the undercoat upper layer coating solution b-2 described below was applied so as to have a dry film thickness of 0.1 μm.

Undercoat upper layer coating liquid a-2 Gelatin 0.4 g / m ² silica particles (average particle size 2 μm) 0.01 g / m ² Undercoat upper layer coating liquid b-2 Styrene-butadiene copolymer latex liquid (solid content 20%) 0.08 g / m ² polyethylene glycol (mass average molecular weight 900) 0.036 g / m ² silica particles (average particle diameter 3 μm) 0.01 g / m ² Preparation of photosensitive silver halide emulsion A Inert gelatin 7 in 900 ml of water After dissolving 0.5 g and 10 mg of potassium bromide to adjust the temperature to 35 ° C. and pH to 3.0, 370 ml of an aqueous solution containing 74 g of silver nitrate and potassium bromide and iodide having a molar ratio of (98/2) equivalent thereto. 370 ml of an aqueous solution containing potassium iodide was added over 10 minutes by the controlled double jet method while maintaining the pAg at 7.7. Then 4-hydroxy-6-methyl-
0.3 g of 1,3,3a, 7-tetrazaindene was added, the pH was adjusted to 5.0 with NaOH, and the average particle size was adjusted to 0.
Cubic silver iodobromide grains having a grain size variation coefficient of 8% and a [100] plane ratio of 87% were obtained. This emulsion was coagulated and sedimented using a gelatin coagulant, desalted, and then added with 0.1 g of phenoxyethanol, pH 5.9 and pAg 7.5.
To obtain a photosensitive silver halide emulsion A.

Preparation of Powdered Organic Silver Salt A 111.4 g of behenic acid, 83.8 g of arachidic acid and 54.9 g of stearic acid were dissolved in 4720 ml of pure water at 80 ° C. Next, 540.2 ml of a 1.5 M / L sodium hydroxide aqueous solution was added while stirring at high speed, and the mixture was sufficiently stirred. Next, 6.9 ml of concentrated nitric acid was added and then cooled to 55 ° C. to obtain an organic acid sodium salt solution. With the temperature of the organic acid sodium salt solution kept at 55 ° C., 450 ml of pure light silver halide emulsion A (containing 0.038 mol of silver) and pure water
Was added and stirred for 5 minutes. Next, 1M / L silver nitrate solution 7
60.6 ml was added over 2 minutes, the mixture was further stirred for 20 minutes, water-soluble salts were removed by filtration, and the mixture was dried.

Preparation of Coating Solution for Photosensitive Layer Each of the following layers was sequentially formed on the support having the undercoating described above so that the photosensitive layer side was A-2, and samples 101 to 113 were prepared.
Was produced. The drying was carried out at 75 ° C. for 1 minute.

Photosensitive layer side coating first layer: antihalation layer (AH) layer Binder (PVB-1: degree of polymerization 600) 1.2 g / m ² antihalation dye (C1) 2 × 10 ⁻⁵ mol / m ² Second layer: photosensitive layer The photosensitive layer was prepared by adding the following composition to a methyl ethyl ketone solution to prepare a coating solution.

Organic silver salt (including silver halide) Silver amount 1.2 g / m ² Binder (PVB-1: degree of polymerization 600) 5.6 g / m ² Crosslinking agent: Formaldehyde 0.2 mmol / m ² Sensitizing dye (A1) 2.1 × 10 ⁻⁴ mol / Ag1 mol Antihalation dye: (C1) 1.1 × 10 ⁻⁵ mol / m ² Starburst molecular compound represented by general formula (1): Table 1. Description 1.3 × 10 ⁻⁴ mol / m ² antifoggant 1: pyridinium hydrobromide perbromide 0.3 mg / m ² antifoggant 2: isothiazolone 1.2 mg / m ² developer: 2,5-di- (Tert-Butyl) -4-methylphenol 3.3 mmol / m ² Third layer: protective layer Binder (cellulose acetate butyrate) 1.2 g / m ² Silica matting agent (number average particle diameter 3 μm) 0.5 g / m ²

[0077]

[Chemical 20]

A back layer and a protective layer for the back layer were coated on the side opposite to the photosensitive layer (undercoating B-2 layer side).

Back layer surface coating First layer: Back layer Binder (PVB-1: degree of polymerization 600) 1.2 g / m ² Dye C1 (same as AH and photosensitive layer) 70 mg / m ² Second layer: back layer Protective layer Cellulose acetate butyrate 0.8 g / m ² Matting agent (PMMA: number average particle size 3 μm) 0.02 g / m ² Surfactant (polyfluorooctyloxyethyl sulfonic acid) 0.02 g / m ^{2 For} photographic performance The conditions for evaluation exposure and development are 81 for the photothermographic image forming material.
It was exposed with a laser sensitometer having a semiconductor laser of 0 nm, and then subjected to heat development treatment at 120 ° C. for 8 seconds using a heating drum. At that time, exposure and development are 25 ° C. and relative humidity is 50.
I went to a room where the humidity was adjusted to%. The sensitivity and fog of the obtained image were evaluated by an automatic densitometer. The sensitivity was evaluated by the reciprocal of the ratio of the exposure dose that gives a density 0.3 higher than the fog.
For the measurement of fog, an unexposed sample was thermally developed and the density was measured. The evaluation of silver tone is a visual five-level sensory evaluation method, rank 5 is the best black tone, rank 1 is the worst yellowish color tone, and rank 3 is a color tone of a level that is practically no problem, and rank 4 is Between Rank 5 and Rank 3, Rank 2 was between Rank 3 and Rank 1.

For the evaluation of scratch resistance, the sample was rubbed while applying a load of 5 kPa with an uneven roller having a depth of 3 μm, and the scratch level was visually evaluated. Table 1 shows the results of evaluation with 5 as the level without scratches, 1 as the level with the most scratches, and 3 as the level with moderate and practically no problem.

[0081]

[Table 1]

When the starburst molecular compound of the present invention is used, a photothermographic image-forming material having low fog in photographic characteristics, high sensitivity, excellent silver color tone, and scratch resistant can be obtained.

Example 2 As in Example 1, the starburst molecular compound represented by the general formula (1) shown in Table 2 was added to the photosensitive layer at 2.2 × 10 ⁻⁴ mol / m ² and the general formula (2). ) Was added to the photosensitive layer in an amount of 4.2 × 10 ⁻⁴ mol / m ² to give Sample 2
01-210 was produced. Performance evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

[0084]

[Table 2]

From the results of Example 2, it is understood that when the compound of the present invention and the phthalazine compound are used, the silver color tone is excellent and the scratch resistance is improved.

Example 3 As in Example 1, the starburst molecular compound represented by the general formula (1) shown in Table 3 was used in the photosensitive layer at 1.8 × 10 ⁻⁴ mol / m ² and the general formula (3). ) Is added to the photosensitive layer in an amount of 2.4 × 10 ⁻⁴ mol / m ² to give Sample 3
01 to 312 were produced. Performance evaluation was performed in the same manner as in Example 1. The results are shown in Table 3.

[0087]

[Table 3]

When the starburst molecular compound and mercapto compound of the present invention are used, a photothermographic image forming material excellent in silver tone and scratch resistance can be obtained.

Example 4 In the same manner as in Example 1, the starburst molecular compound represented by the general formula (1) shown in Table 4 was added to the photosensitive layer at 1.6 × 10 ⁻⁴ mol / m ² and the general formula (4). (3) was added to the photosensitive layer at 3.1 × 10 ⁻⁴ mol / m ² to prepare Samples 401 to 412. Performance evaluation was performed in the same manner as in Example 1. The results are shown in Table 4.

[0090]

[Table 4]

When the starburst molecular compound and disulfide compound of the present invention are used, it is possible to obtain a photothermographic image forming material having low fog and excellent silver color tone and scratch resistance.

Example 5 In the same manner as in Example 1, the starburst molecular compound represented by the general formula (1) shown in Table 5 was used in the photosensitive layer at 2.2 × 10 ⁻⁴ mol / m ² and ^{2 as} a reducing agent. Samples 501 to 512 were prepared by using 3.3 mmol / m ^{2 of} the bisphenol compound represented by the general formula (5) instead of 5,5-di- (tert-butyl) -4-methylphenol. Performance evaluation was performed in the same manner as in Example 1. The results are shown in Table 5.

[0093]

[Table 5]

When the starburst molecular compound of the present invention and the reducing agent of the present invention are used, a photothermographic image forming material having low fog and excellent silver color tone and scratch resistance can be obtained.

Example 6 As in Example 1, the starburst molecular compound represented by the general formula (1) shown in Table 6 was added to the photosensitive layer in an amount of 1.8 × 10 ⁻⁴ mol / m ² , and The cross-linking agent of the invention was added to the photosensitive layer in an amount of 0.2 mmol / m ² instead of formaldehyde. The photographic performances of the obtained samples 601 to 612 were evaluated in the same manner as in Example 1. The obtained results are shown in Table 6.

[0096]

[Table 6]

When the starburst molecular compound and the crosslinking agent of the present invention are used, a photothermographic image forming material having a low fog and excellent silver color tone and scratch resistance can be obtained.

[0098]

According to the present invention, it is possible to provide a photothermographic image forming material having high sensitivity, low fog, improved silver tone, and high film strength which is hardly scratched.

Claims (7)

[Claims] 1. A photothermographic image-forming material containing a photosensitive silver halide grain, an organic silver salt, a reducing agent and a binder for the organic silver salt on a support, which is represented by the following general formula (1). A photothermographic image-forming material comprising at least one starburst molecular compound. [Chemical 1] [In the formula, A ₁ , B ₁ , B ₂ , B ₃ and B _n are trivalent to hexavalent atoms or a group of atoms forming a ring, n1 is a positive integer of 3 to 6, and n2 and n3 to nn are 2 Represents a positive integer of ~ 6. ] 2. The photothermographic image-forming material according to claim 1, wherein at least one starburst molecular compound is contained in the photosensitive layer or a layer adjacent to the photosensitive layer. 3. The photothermographic image-forming material according to claim 1, which contains at least one kind of phthalazine compound represented by the following general formula (2). [Chemical 2] [Wherein R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each a hydrogen atom, a halogen atom, a cyano group, a hydroxy group, an amino group, a sulfonic acid group and its salt, a carboxylic acid group and its A salt, a phosphoric acid group and a salt thereof, an alkyl group having 1 to 20 carbon atoms, an alkenyl group, an alkoxy group, a 5-membered or 6-membered aromatic group and a heterocyclic group, respectively. ] 4. The photothermographic image-forming material according to claim 1, wherein at least one mercapto compound represented by the following general formula (3) is contained in the photosensitive layer or a layer adjacent to the photosensitive layer. . [Chemical 3] [In the formula, W ₁ is an NH group, an oxygen atom, a sulfur atom and CH ₂
Represents a group, Q represents a 5- or 6-membered aromatic or heterocyclic group which may have a substituent, L ₂ represents a divalent linking group, M represents a hydrogen atom or Na, K And an alkali metal atom such as Li atom, and p represents 0 or 1. ] 5. The photothermographic image-forming material according to claim 1, wherein the photosensitive layer or a layer adjacent to the photosensitive layer contains at least one disulfide compound represented by the following general formula (4). . [Chemical 4] [In the formula, Y ₁ and Y ₂ each represent a 5-membered or 6-membered aromatic ring group or hetero ring group which may have a substituent. ] 6. The photothermographic image-forming material according to claim 1, wherein at least one reducing agent represented by the following general formula (5) is contained in the photosensitive layer or a layer adjacent to the photosensitive layer. . [Chemical 5] [In the formula, R ′ and R ″ represent a substituent, and L ₃ represents a divalent linking group.] 7. The photothermographic image according to claim 1, wherein the binder is crosslinked with at least one crosslinking agent selected from an isocyanate compound, a vinylsulfonyl compound, an epoxy compound and an alkoxysilane compound. Forming material.