JP2002258433A - Photothermographic image forming material and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photothermographic image forming material ensuring low fog, high sensitivity and high density and excellent in image preservability and to provide an image forming method less liable to cause interference fringes and giving a uniform finish of development in relation to image formation. SOLUTION: In the photothermographic image forming material having a photosensitive layer containing photosensitive silver halide grains of 20-80 nm average grain diameter, an organic silver salt, a reducing agent and a binder on the base, the photosensitive layer comprises a first photosensitive layer closest to the base and a second photosensitive layer adjacent to the first photosensitive layer, the content of the photosensitive silver halide grains is smaller in the first photosensitive layer than in the second photosensitive layer and the contents of a hydrazide compound and a vinyl compound having an electron withdrawing group in its molecule in the photosensitive layer are larger in the first photosensitive layer than in the second photosensitive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photothermographic image forming material capable of obtaining low fog, high sensitivity and high density, and having good image storability. The present invention relates to an image forming method capable of obtaining a developed finish.

[0002]

2. Description of the Related Art In recent years, in the medical field, from the viewpoint of environmental protection and workability, a photographic material which forms an image by light or heat treatment and which does not generate waste liquid due to wet processing has been strongly desired. The technology relating to photothermographic materials for photographic technology, which can form a high-resolution and clear black image by development using both heat, has been commercialized and rapidly spread. Since these photothermographic materials are usually developed at a temperature of 80 ° C. or higher, they are distinguished from conventional wet photographic light-sensitive materials which are liquid-developed in the range of 25 ° C. to 45 ° C., and are called photothermographic image forming materials.

This photothermographic image forming material (hereinafter abbreviated as photothermographic material) enables thermal development by including silver halide particles, organic silver salts, a reducing agent and the like in a photosensitive layer. . However, after heat development, in the unexposed areas, the photosensitive silver halide and the reducing agent remain at the same time, so that fog increases and the density of high-density areas of 2.5 or more decreases. It was necessary to solve the problem that storage stability deteriorated.

One solution is to have a compound which generates an acid or an oxidizing agent by light or heat. These techniques are disclosed in US Pat. Nos. 3,874,946 and 4,452,8.
No. 85, No. 4,546,075, No. 4,756,99
9, No. 5,340,712, JP-B-54-165
JP-A-50-137126, JP-A-7-2781
No. 9-265150, and the like. However, the polyhalomethane compound has a side effect of suppressing the development progress of the image area, and has a problem that it is difficult to obtain high sensitivity.

As a method for obtaining high sensitivity, there is disclosed a technique using a hydrazide compound having an action of accelerating development in addition to an efficient chemical sensitization or spectral sensitizer. And JP-A-8-234393 and JP-A-8-234393.
No. 1-65020. The hydrazide is in particular at a concentration of 2.
Since it has an action of accelerating the development of a high-density portion such as 5 or more, it is applied to a photosensitive material for printing as a high contrast agent.
Separately, as a method of obtaining high sensitivity as a development accelerating compound,
Use of a vinyl compound having an electron-withdrawing group is described in JP-A-11-95366 and JP-A-11-231559. The vinyl compound also has an effect of accelerating the development of a high-density portion having a density of 2.5 or more, and is therefore applied to a photosensitive material for printing as a high contrast agent.

Therefore, there is a method of using a compound which generates an acid or an oxidizing agent by light or heat during storage in order to improve the image storability, but these compounds have a side effect of lowering the sensitivity. Another technique was needed to obtain.
Combining these technologies reduces fog and achieves high sensitivity.

As a method of obtaining high sensitivity, in a wet processing silver halide photographic material which is not a heat development method,
A technique for providing two photosensitive layers is known. The reason for this is that the portion of the photosensitive layer close to the support (lower layer) has less incident light for photosensitization than the surface, so that the lower layer is made more sensitive to increase the development efficiency of silver halide grains and to increase the substantially higher efficiency. This is a technique to obtain sensitivity. In order to increase the sensitivity of the lower layer, a development-sensitizing sensitizer such as chemical sensitization, spectral sensitization or hydrazide was used. This was a method of increasing the sensitivity of silver halide grains in the lower photosensitive layer or obtaining a high contrast.

However, in a photothermographic material in which silver halide grains, an organic silver salt and a reducing agent are present, if the photosensitive layer is divided into two layers and the sensitivity of the lower photosensitive layer is merely increased, low fog, high sensitivity, High density and image storability could not all be improved to a satisfactory level.

In recent years, image formation of photothermographic materials has involved
The method of exposing with a laser has become widespread. Due to the coherent characteristics of the laser beam, there is also a problem that two beams reflected by the laser incident light at the front and back interfaces of the support interfere with each other to cause unevenness. As a method for avoiding this interference, a longitudinal multi-exposure method in which laser beams having different wavelengths are superposed to form a multiplexed wave by eliminating coherent characteristics of the laser, or a two-beam irradiating a plurality of laser beams having different wavelengths There is an irradiation method, a so-called double beam exposure method and the like. Each of these methods is a method for reducing the coherent characteristics, and there is a problem that an excessive amount degrades the image quality.

As another approach, a photothermographic material is provided with an antihalation layer for suppressing reflected light, but there is a problem that excessive antihalation reduces the sensitivity. In order to suppress reflection by utilizing light scattering in silver halide grains, there is a method in which the photosensitive layer is divided into two layers and low-sensitivity silver halide grains are contained in the photosensitive layer close to the support. Has a problem that the sensitivity of the photothermographic material is lowered. As a method of preventing interference due to reflection of incident light, a satisfactory method has not yet been found.

[0011]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a photothermographic image forming material capable of obtaining low fog, high sensitivity and high density and having excellent image storability.
Another object of the present invention is to provide an image forming method which is less likely to cause interference unevenness during image formation and gives a uniform development finish.

[0012]

An object of the present invention is to provide a photosensitive composition containing photosensitive silver halide grains having an average grain size of 20 to 80 nm, an organic silver salt, a reducing agent and a binder on a support. In a photothermographic image forming material having a layer, the photosensitive layer comprises a first photosensitive layer closest to a support and a second photosensitive layer adjacent to the first photosensitive layer, and the content of the photosensitive silver halide grains is Photothermographic image formation in which the first photosensitive layer <the second photosensitive layer, the content of the hydrazide compound in the photosensitive layer and the content of the vinyl compound having an electron-withdrawing group in the molecule is the first photosensitive layer> the second photosensitive layer Achieved by the material. The photosensitive silver halide grains of the second photosensitive layer of the photothermographic image forming material are chemically sensitized with an unstable sulfur or selenium compound, and at least one of the photosensitive silver halide grains of the photosensitive layer is oxidized. Heat treatment in the presence of an agent, and at least one of -NH- of -NHNH- groups of the hydrazide compound.
Is a benzoyl group which may have a substituent, a phenyl group,
It is a preferred embodiment that both have a group selected from a triphenylmethyl group and that the vinyl compound having an electron withdrawing group has an electron donating group at the same time.

[0013] It is an object of the present invention that the scanning laser light for recording an image on the photothermographic image forming material is a double beam having the same wavelength and different incident angles. It is also achieved by an image forming method, which is exposure by a multi-laser scanning exposure device.

Hereinafter, the present invention will be described in detail. The photothermographic material (especially for medical use) of the present invention comprises two different photosensitive layers containing at least photosensitive silver halide grains, an organic silver salt, a reducing agent and a binder, on an undercoated support. Can be manufactured. The two photosensitive layers are characterized by containing photosensitive silver halide grains described below and hydrazide compounds and / or vinyl compounds in different amounts. That is, a first photosensitive layer closest to the support and a second photosensitive layer adjacent to the photosensitive layer are provided on the support. If necessary, a second photosensitive layer may be provided via an intermediate layer. Is also good.

It is necessary that the content per unit area of the photosensitive silver halide grains in the first photosensitive layer is smaller than the content of the silver halide grains in the second photosensitive layer. At this time, the hydrazide compound and / or the vinyl compound contained in the first photosensitive layer is characterized by being larger than the content of the compounds contained in the second photosensitive layer. The amount at this time may be either mass or molar equivalent.

A protective layer is usually provided on the photosensitive layer. A backing layer or a backing protective layer may be provided on the back side of the photosensitive layer with respect to the support, or a photosensitive layer may be provided on both sides. The following are hydrazide compounds, vinyl compounds, organic silver salts, reducing agents, photosensitive silver halide grains, chemical sensitizers for increasing the sensitivity of silver halide grains, oxidizing agents, and spectral sensitizers added to the photosensitive layer. The sensitizer, the binder, the crosslinking agent that crosslinks the binder, the phthalazine compound that is a color tone agent or an accelerator, and the like will be sequentially described in detail.

(Hydrazide compound) As the hydrazide compound which is a development accelerator, a compound having a -CONHNHCO- bond is preferable, and a particularly preferable hydrazide compound is a carbonyl (-CO-) group or a sulfonyl (-SO _2- ) A compound in which groups are linked. A preferred structure can be represented by the following general formula (I).

[0018]

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In the formula, R ₁₁ represents an aromatic group having a benzene ring or a naphthalene ring, a heterocyclic group having a pyridine ring, a pyrrole ring, a thiophene ring or a furan ring, and a triphenylmethyl group. It may have a substituent. As a substituent, McGraw-Hill in 1940
Book Company (McGrawHill Book Co.,
N. Y. ) Published by Physical Organic
Chemistry (Physical Organic C
Chemistry), p. 78. P. Hamm
ett (LP Hammett) has a substituent constant of -1.0 to
Any substituent within the range of 1.0 can be selected. Further, in 1958, D.C. H. McDaniel
(DH MacDaniel), H.M. C. Brown
(H. C. Brown) et al.—Substituents modified by J. Org. Chem., 1958, 23, 42, Journal of Organic Chemistry.
It may be the one described on page 0. L represents a linking group, representing a carbonyl group, a sulfonyl group, a sulfinyl group, or the like, and n represents 1 or 0. R ₁₂ represents an alkyl group having 1 to ₁₂ carbon atoms (eg, methyl, ethyl, butyl, octyl, methoxymethyl) and an alkoxy group having 1 to 12 carbon atoms (eg, methoxy, ethoxy, butoxy, octoxy).

The hydrazide compound can be used not only as a development accelerator but also as a contrast regulator or a high contrast agent. Preferred compounds are shown below, but are not limited thereto.

[0021]

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[0022]

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The method of adding the hydrazide compound to the coating solution is as follows. May be
It may be dispersed in water and added to the photosensitive layer, the protective layer, the backing layer, and the backing protective layer. Preferred layers are photosensitive layers and non-photosensitive layers adjacent to photosensitive layers.

The total amount of the protective layer for the photosensitive layer or the backing layer or the protective layer for the backing layer may be 1 mg to 10 g / m ² on the one side of the support.
It is preferred that If the amount is less than the above range, the effect of promoting the development of the hydrazide compound and the effect of increasing the contrast cannot be obtained.

(Vinyl compound) The vinyl compound used in the present invention can be called a 1-hydroxyethylene derivative, and preferably has at least one electron-withdrawing group at the 2-position. Further, those having an electron withdrawing group and an electron donating group at the 2-position are preferred. Further, when the electron withdrawing group is 2
May be provided. The electron-withdrawing or electron-donating group has a substituent constant of -1.0 to 0 from among the substituents described in the Hammett's rule described in the hydrazide compound and the additional substituents such as Mac Daniel and Brown. Electron donating groups and 0 to 1.0 electron withdrawing groups can be selected. The structure of a particularly preferred vinyl compound is represented by the following general formula (I
Indicated by I).

[0026]

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In the formula, at least one of R ₂₁ and R ₂₂ represents an electron withdrawing group, and the other represents an electron withdrawing group or an electron donating group. As these substituents, the Hammett substituent described in the above hydrazide compound or the electron withdrawing group or electron donating group of Mac Daniel and Brown can be selected. Further, R ₂₁ and R ₂₂ may be bonded to each other to form a saturated or unsaturated ring having a 5- or 6-membered cyclic structure.
Further, it may be a heterocycle into which a hetero atom has been introduced. These rings may further have substituents such as those mentioned by Hammett and MacDaniel. Preferred vinyl compounds are shown below.

[0028]

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[0029]

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The method for adding the vinyl compound to the coating solution is exactly the same as that for the hydrazide compound. Preferred additive layers are a photosensitive layer and a layer adjacent to the photosensitive layer. The amount used is exactly the same as the hydrazide compound, and the total amount used on one side of the support is preferably 1 mg to 10 g / m ² . If the amount is less than this range, the effect of promoting the development (high sensitivity) and high contrast of the vinyl compound cannot be obtained, and if the amount exceeds this range, the coating property deteriorates and fogging increases.

(Organic silver salt) The organic silver salt contained in the photothermographic material is a reducible silver source, and organic acids, heteroorganic acids and silver salts of acid polymers containing a reducible silver ion source can be used. Used. Also useful are organic or inorganic silver salt complexes wherein the ligand has a total stability constant for silver ions of 4.0 to 10.0. Preferred organic acids for forming organic silver salts are gallic acid, oxalic acid, behenic acid, stearic acid,
Palmitic acid, lauric acid, arachidic acid, arachidonic acid, docosanoic acid and the like can be mentioned.

(Reducing Agent) Examples of the reducing agent preferably used are described in US Pat. Nos. 3,770,448 and 3,773,5.
No. 12, No. 3,593,863, etc.,
Typically, the following compounds are mentioned.

K-1: 1,1-bis (2-hydroxy-
3,5-dimethylphenyl) -3,5,5-trimethylhexane K-2: bis (2-hydroxy-3-t-butyl-5-
Methylphenyl) methane K-3: 2,2-bis (4-hydroxy-3-methylphenyl) propane K-4: 4,4-ethylidene-bis (2-t-butyl-
6-Methylphenol) K-5: 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane The above compound is used by dispersing in water or dissolving in an organic solvent. As the organic solvent, alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, and aromatic solvents such as toluene and xylene can be arbitrarily selected. The amount of reducing agent used is 1 × per mole of silver.
It is 10 ^-2 to 10 mol, preferably 1 × 10 ^{-2 to} 1.5 mol.

(Photosensitive Silver Halide Particles) The photosensitive silver halide particles can be prepared by any method known in the field of photographic technology such as a single jet method or a double jet method, for example, by an ammonia method emulsion, a neutral method, or an acid method. Or the like, and then mixed with other components and introduced into the composition used in the present invention. In this case, in order to sufficiently contact the photosensitive silver halide with the organic silver salt, for example, as a protective polymer for preparing the photosensitive silver halide, US Pat. Nos. 3,706,564 and 3,7
06,565, 3,713,833, 3,74
No. 8,143, British Patent No. 1,362,970, etc., means using a polymer other than gelatin such as polyvinyl acetal, and photosensitive halogenation as described in British Patent No. 1,354,186. Means for enzymatic degradation of silver emulsion gelatin or US Pat. No. 4,076,539
As described in the above item, various means such as a method of omitting the use of a protective polymer by preparing photosensitive silver halide grains in the presence of a surfactant can be applied.

The photosensitive silver halide preferably has a small grain size in order to suppress haze after image formation and to obtain good image quality. 2 in average particle size
0-80 nm, preferably 30-60 nm, especially 35-
55 nm is preferred. The shape of the silver halide is not particularly limited, and may be cubic, octahedral, so-called normal crystals, or non-normal crystals, such as spherical, rod-like, or tabular grains. The silver halide composition is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide.

The amount of the photosensitive silver halide is suitably 50% by mass or less, preferably 25 to 0.1% by mass, more preferably 1% by mass, based on the total amount of the silver halide and the organic silver salt.
The range is 5 to 0.1% by mass. The reaction temperature, the reaction time and the reaction time when a step of converting a part of the organic silver salt into silver halide by using a silver halide forming component (halogen salts such as potassium bromide and sodium chloride and various halides) are included. Various conditions such as a reaction pressure can be appropriately set according to the purpose of production.

(Chemical Sensitizer) The photosensitive silver halide prepared by the above-mentioned various methods can be chemically sensitized with, for example, a sulfur-containing compound, a gold compound, a platinum compound, a palladium compound, a silver compound, or a combination thereof. can do. The method and procedure of this chemical sensitization are described, for example, in US Pat. No. 4,036,650, British Patent 1,518,
No. 850, JP-A-51-22430 and JP-A-51-783.
Nos. 19 and 51-81124 can be referred to.

Particularly preferred chemical sensitizers are unstable sulfur compounds or selenium compounds which can generate silver sulfide or silver selenide when heat is applied in the presence of silver halide grains. Preferred compounds are compounds based on thiourea or selenourea, in which the amino group of each basic structure is substituted with an alkyl group having 1 to 12 carbon atoms or a phenyl group having an electron-withdrawing or electron-donating substituent. Is preferred. Another preferred structure is a phosphoselenide or phosphosulfide compound. Sulfur or selenium is bonded to a phosphorus atom, and at the same time, an alkyl group having 1 to 12 carbon atoms (methyl, ethyl, butyl, octyl, etc.) or an aromatic group (phenyl, naphthyl, p-chlorophenyl,
2,3,4,5,6-pentachlorophenyl). Preferred examples of the compound are shown below.

[0039]

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(Oxidizing Agent) The oxidizing agent used in the present invention is preferably hydrogen peroxide, a chloramine compound, a tetrazolium compound, or the like. The tetrazolium compound includes an alkyl group (methyl, ethyl, butyl, octyl, etc.) or an alkoxy group (methoxy, ethoxy, butoxy, octoxy, etc.), a sulfo group in at least one of the phenyl groups of the 1,3,5-triphenyltetrazolium compound. It is preferable to introduce a carboxyl group, a hydroxyl group, a hydroxyethoxy group, a cyano group, a nitro group or the like.

The preferable addition amount of the oxidizing agent is 1 × 10 ⁻⁸ to 1 × 10 ⁻² mol per 1 mol of silver halide. The oxidizing agent is preferably added in combination with the above-mentioned unstable sulfur compound which is a chemical sensitizer. The following compounds are particularly preferable as the oxidizing agent, but are not limited thereto.

PZ-1: hydrogen peroxide PZ-2: chloramine-B (sodium N-chlorobenzenesulfonamide) PZ-3: chloramine-T (sodium N-chloro-4-methyllbenzenesulfonamide) PZ- 4: 1,3,5-trimethoxyphenyltetrazolium chloride PZ-5: 1,3,5-trimethylphenyltetrazolium chloride PZ-6: 1,3,5-triphenyltetrazolium chloride The oxidizing agent is a silver halide particle. Is dissolved in water or an organic solvent after the formation of
It is preferably added in the range of from ^10-8 to 1 mol, preferably from 1 × ^10-7 to ^10-2 mol, most preferably from 1 × ^10-6 to 1 × ^10-3 mol. After the addition, the treatment is performed at a temperature of 30 ° C. to 97 ° C. for 1 minute to 8 hours, preferably for 5 minutes to 1 hour.

As for the method of adding the oxidizing agent and the chemical sensitizer, it is preferable to perform the chemical sensitization after adding the oxidizing agent and performing the oxidation treatment, but the chemical sensitization may be performed during the oxidation treatment. Oxidation treatment may be performed after chemical sensitization. Further, the oxidation treatment may be performed both before and after the chemical sensitization. The conditions in that case may be the same or different.

(Spectral Sensitization) The silver halide grains can be sensitized with a spectral sensitizing dye if necessary. For example, JP-A Nos. 63-159841, 60-140335, and 6
Nos. 3-231437, 63-259651 and 63
-304242, 63-15245, U.S. Patent Nos. 4,639,414, 4,740,455, 4,741,966, 4,751,175, and 4,835,096 And the like.

(Binder) Polymer binders used for the photosensitive layer or the non-photosensitive layer of the photothermographic material include polyvinyl butyral, polyacrylamide, polystyrene, polyvinyl acetate, polyurethane, polyacrylate, and styrene-butadiene. Examples thereof include a polymer, an acrylonitrile-butadiene copolymer, a vinyl chloride-vinyl acetate copolymer, and a styrene-butadiene-acrylic acid copolymer. After coating and drying to form a film, those having a low equilibrium water content of the coating film are preferable, and particularly those having a low water content include, for example, organic solvent-based cellulose acetate, cellulose acetate butyrate, and polyacetal. Can be. Polyacetal produces polyvinyl alcohol by saponifying polyvinyl acetate,
The polyacetal obtained by reacting the polyvinyl alcohol with an aldehyde compound means a polyacetal which is preferably acetalized with butylaldehyde and a polyacetal which is acetalized with acetaldehyde (polyacetal in a narrow sense). Acetalization theoretically exists up to 1 to 100%, but practically the range of 20 to 95% is preferable.

(Crosslinking agent) The binder can maintain the adhesion to the lower layer and the upper layer by forming the film alone, and can obtain a film strength which is hard to be damaged. Adhesion and film strength can be increased. Preferred crosslinking agents for the present invention are those having an isocyanate group, a vinylsulfonyl group or an epoxy group. Particularly preferred crosslinking agents include polyfunctional crosslinking agents having at least two isocyanate groups, vinylsulfonyl groups or epoxy groups in the molecule.

Specific examples of preferred crosslinking agents are shown below. H-1: hexamethylene diisocyanate H-2: hexamethylene diisocyanate trimer H-3: tolylene diisocyanate H-4: p-phenylene diisocyanate H-5: xylylene diisocyanate H-6 : 1,3-bis (isocyanatomethyl) cyclohexane H-7: tetramethylene xylylene diisocyanate H-8: mi-propenyl-α, α-dimethylbenzyl isocyanate

[0048]

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The crosslinking agent may be added by dissolving it in water, alcohols, ketones or non-polar organic solvents.
It may be dispersed and added as a solid in the coating solution. The addition amount is preferably equivalent to the group to be crosslinked, but may be increased up to 10 times or reduced to 1/10 or less. If the amount is too small, the crosslinking reaction does not proceed. If the amount is too large, the unreacted crosslinking agent deteriorates photographic properties, which is not preferable.

(Phthalazine compound) In the present invention, it is preferable to use a phthalazine compound as a development accelerator or a color tone agent. Particularly, a phthalazine compound having a substituent at the 1,4,6,7-position of the phthalazine ring is preferable. Examples of the substituent include an aliphatic group such as an alkyl group or an alkenyl group which may have 1 to 26 carbon atoms, an aromatic group such as a phenyl group and a naphthyl group, a pyridyl group, a furyl group, a pyrimidyl group, and an imidazole group. And a thiophenyl group.

The phthalazine compound is added to the coating solution by dissolving it in a ketone such as ethyl ketone or acetone, or an organic solvent such as an aromatic solvent such as toluene or xylene or a non-aromatic solvent such as normal hexane or decane. May be
It may be dispersed in water and added to the photosensitive layer, the protective layer, the backing layer, and the backing protective layer. The amount used is preferably such that the total amount used for the photosensitive layer or the protective layer of the photosensitive layer is 1 mg to 10 g / m ² . If the amount is less than this range, the phthalazine compound does not have the effect of promoting development and the effect of improving color tone. If the amount exceeds this range, coatability and fog increase, which is not preferable.

Preferred specific examples of the phthalazine compound are shown below.

[0053]

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(Dye) The photothermographic material of the present invention may contain an antihalation layer or an antihalation antihalation layer (AH layer) or a backing layer (BC) if necessary.
Layer) is provided. The dye used in the AH layer or the BC layer may be any dye that absorbs image exposure light,
Preferred examples are described in JP-A-2-216140 and 7-1.
No. 3295, No. 7-11432, U.S. Pat.
And the dyes described in U.S. Pat.

(Support) As the support, polyethylene terephthalate (PET), polyethylene naphthalate (PEN) or syndiotactic polystyrene (SP)
S) and the like are preferable, and those having a thickness of 50 to 400 μm, which is biaxially stretched or heat-fixed, has high optical isotropy and good dimensional stability, are preferable.

Next, an image forming method using the photothermographic material of the present invention will be described. (Image exposure) JP-A-9-304869 and JP-A-9-304869 describe exposure methods for photothermographic materials.
Laser exposure can be performed according to the method described in JP-A-311403 and JP-A-2000-10230. In the exposure of the photothermographic material of the present invention, it is desirable to use a light source appropriate for the color sensitivity imparted to the photographic material. For example,
If the photographic material can be felt in infrared light, it can be applied to any light source in the infrared light range, but from the viewpoint that the laser power is high power, the photographic material can be made transparent, etc. Infrared semiconductor laser (780 nm, 810 n
m) is preferably used.

The exposure is preferably performed by laser scanning exposure, but various methods can be adopted as the exposure method. For example, as a first preferred method, there is a method using a laser scanning exposure machine in which the angle (incident angle) between the exposure surface of the photographic material and the scanning laser beam does not become substantially perpendicular. Here, “not substantially perpendicular” means that the angle is most perpendicular to the laser scanning, preferably 55 to 88 degrees, more preferably 60 to 86 degrees.
Degrees, more preferably 65-84 degrees, most preferably 70 degrees.
Say ~ 82 degrees.

The beam spot diameter on the photographic material exposure surface when the laser light is scanned on the photographic material is preferably 200 μm or less, more preferably 100 μm or less. This is preferable because the spot diameter is smaller in that the “shift angle” of the laser incident angle from the perpendicular can be reduced.
Note that the lower limit of the beam spot diameter is 10 μm. By performing such laser scanning exposure, it is possible to reduce image quality deterioration due to reflected light, such as occurrence of interference fringe-like unevenness.

As another method, it is preferable that the exposure of the photographic material is performed using a laser scanning exposure machine that emits a scanning laser beam which is a vertical multi. Image quality deterioration such as generation of interference fringe-like unevenness is reduced as compared with the scanning laser beam in the longitudinal single mode. To achieve vertical multiplication, a method such as multiplexing, using return light, or superimposing high frequency is preferable. In addition, the vertical multi means that the exposure wavelength is not single, and usually,
The distribution of the exposure wavelength may be 5 nm or more, preferably 10 nm or more. The upper limit of the exposure wavelength distribution is not particularly limited, but is usually about 60 nm.

Further, as another embodiment, it is preferable to form an image by scanning exposure using two or more lasers. Such an image recording method using a plurality of lasers is used in an image writing means of a laser printer or a digital copier which writes an image by a plurality of lines in one scan due to a demand for high resolution and high speed. Technology,
For example, it is known from JP-A-60-166916. This is a method in which a laser beam emitted from a light source unit is deflected and scanned by a polygon mirror to form an image on a photoreceptor via an fθ lens or the like. This is the same laser scanning principle as a laser imager or the like. An optical device.

(Heat Developing Apparatus) An apparatus for developing a photothermographic material is disclosed in JP-A-11-65067 and JP-A-11-72897.
And the devices described in JP-A-11-84619 and the like can be used.

[0062]

EXAMPLES The present invention will be described below with reference to examples, but embodiments of the present invention are not limited thereto. Unless otherwise specified, “%” in the examples represents “% by mass”.

Example 1 <Preparation of Subbed Support> A PET support having a thickness of 175 μm was subjected to a corona discharge treatment of 12 W / m ² · min.
On one surface, the following undercoating coating solution a-1 was dried to a thickness of 0.6 μm.
Is applied and dried to provide an undercoat layer A-1,
On the other side, the following undercoating coating solution b-1 was dried to a dry film thickness of 0.
It was applied to a thickness of 6 μm and dried to form an undercoat layer B-1. (Undercoating solution a-1) A butyl acrylate / t-butyl acrylate / styrene / 2-hydroxyethyl acrylate (30/20/25/25%) copolymer latex liquid (solid content 30%) was diluted 15 times. . (Subbing coating solution b-1) butyl acrylate / styrene /
A glycidyl acrylate / (40/20/40%) copolymer latex liquid (solid content 30%) is diluted 15-fold.

Subsequently, the surface of the undercoat layers A-1 and B-1 was subjected to a corona discharge treatment of 12 W / m ² · min, and the undercoat layer A-1 was coated with the following undercoat upper layer coating solution a -2 is applied and dried to provide an undercoating upper layer A-2 (photosensitive layer side), and an undercoating layer B-
On top of No. 1, a lower pulling upper layer B-2 (BC layer side) having an antistatic function by applying and drying the following lower pulling upper layer coating solution b-2 was provided. (Undercoat upper layer coating solution a-2) Styrene-butadiene 1: 2 copolymer 0.4 g / m ² butyl acrylate / t-butyl acrylate / styrene / 2-hydroxyethyl acrylate / methacrylic acid (30/20 / 25/20/5%) Copolymer Latex liquid (solid content 30%) 0.3 g / m ² (Undercoat upper layer coating solution b-2) Styrene-butadiene 1: 2 copolymer 0.4 g / m ² Conductive tin oxide fine particles (average particle diameter 16 nm) 0.023 g / m ² butyl acrylate / t-butyl acrylate / styrene / 2-hydroxyethyl acrylate / methacrylic acid (30/20/25/20/5%) copolymer A latex solution (solid content: 30%) 0.3 g / m ² An AH layer, a first photosensitive layer, a second photosensitive layer, and a protective layer having the following composition were simultaneously formed on the undercoated support thus prepared. Multi-layer coating was performed. Prior to the application of the photosensitive layer, a BC layer and a BC layer protective layer were simultaneously applied in multiple layers. First, a silver halide was prepared prior to coating, and then an organic silver salt was prepared. <Preparation of silver halide> In 900 ml of water, 7.5 g of inert gelatin and 10 mg of potassium bromide were dissolved and adjusted to a temperature of 12 ° C. and a pH of 3.0, and 370 ml of an aqueous solution containing 74 g of silver nitrate and potassium bromide were added. Aqueous solution containing potassium and potassium iodide (98/2 molar ratio) in equimolar amounts to silver nitrate 3
70 ml was added over 10 minutes by the controlled double jet method while keeping pAg at 7.7. Synchronously with the addition of silver nitrate, the sodium salt of hexachloroiridium was added at 1 × 10 ^-6 mol / mol of silver. Thereafter, 0.3 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene (hereinafter abbreviated as ST-1) was added, the pH was adjusted to 5 with sodium hydroxide, and the average was adjusted. Particle size 3
An emulsion comprising cubic silver iodobromide grains having a diameter of 8 nm, a variation coefficient of the projected diameter area of 8%, and a [100] face ratio of 87% was obtained. This emulsion was coagulated and precipitated using a gelatin coagulant, desalted, and dried to obtain 56 g of a powder. The average particle diameter was changed as follows using this preparation method as a reference formulation.

Silver halide grains having an average grain size of 10 nm:
The temperature at which the solution containing potassium bromide and potassium iodide and the silver nitrate solution are added by a double jet is set to 5 ° C.
Further, 0.2 g of ST-1 was previously added to and dissolved in the gelatin solution.

Silver halide grains having an average grain size of 100 nm: The temperature of the standard formulation was adjusted to 36 ° C. and added by double jet over 16 minutes. After chemical sensitization was completed by double jet addition, the temperature was set to 52 ° C.
The chemical sensitizers of the present invention described in Table 2 were added in an amount of 10 ^-5 mol per mol of silver halide, followed by chemical ripening for 60 minutes.
In the case of carrying out the oxidation treatment, the oxidation treatment agents shown in Tables 1 and 2 are added in an amount of 10 ^-5 mol per mol of silver halide, and the mixture is added at 48 ° C.
For 46 minutes. <Preparation of organic silver salt> Behenic acid 1 was added to 3980 ml of pure water.
11.4 g, arachidic acid 83.8 g, stearic acid 5
4.9 g were melted at 80 ° C. Next, while stirring at a high speed, 540.2 ml of a 1.5 mol aqueous sodium hydroxide solution
Was added and 6.9 ml of concentrated nitric acid was added, followed by cooling to 55 ° C. to obtain a sodium organic acid solution. The temperature of this solution is 5
After stirring for 5 minutes while maintaining the temperature at 5 ° C., 760.6 ml of a 1 mol aqueous silver nitrate solution was added over 2 minutes, and the mixture was further stirred for 20 minutes and filtered to remove water-soluble salts. Thereafter, water washing with deionized water and filtration were repeated until the conductivity of the filtrate reached 2 μS / cm, and finally, after centrifugal dehydration and drying, 358 g of organic silver salt flakes were obtained. <Coating of photosensitive layer and BC layer> On the undercoated support,
The following layers on the photosensitive layer side and the BC layer side were coated. The drying was performed at 45 ° C. for 1 minute on both the photosensitive layer side and the BC layer side. <Coating on BC layer side> On the BC layer side, a BC prepared by dissolving the following composition in a methyl ethyl ketone (MEK) solvent
The layer and the BC protective layer coating solution were simultaneously coated and dried so as to have the following amounts to form a BC layer. (BC layer composition) Binder (PVB-1) 1.8 g / m ² Crosslinker (H-2) 1 × 10 ⁻⁴ mol / m ² Dye (F-1) 2.2 × 10 ⁻⁵ mol / m ²

[0067]

Embedded image

(BC protective layer composition) Binder (cellulose acetate butyrate) 1.1 g / m ² Matting agent (fine silica particles having an average particle diameter of 6 μm) 0.1 g / m ² <Coating on photosensitive layer side> Photosensitive layer On the side, the following AH layer, the first
Each layer coating solution prepared by dissolving the photosensitive layer, the second photosensitive layer, and the surface protective layer composition in a MEK solvent was simultaneously coated and dried so as to have the following coating weight to form a photosensitive layer. (AH layer composition) Binder (cellulose acetate butyrate) 0.4 g / m ² Dye (F-1) 1.3 × 10 ⁻⁵ mol / m ² (first photosensitive layer composition) Silver halide particle powder Organic silver salt flakes described in Tables 1 and 3 Hydrazide compounds described in Tables 1 and 3 Vinyl compound tables described in Tables 1 and 3 Binder (PVB-1) 2.6 g / m ² Spectral sensitizing dye (SD-1) ) 2 × 10 ^-5 mol / m ² antifoggant -1 (pyridinium hydrobromide perbromide) 0.3 mg / m ² antifoggant-2 (isothiazolone) 1.2 mg / m ² reducing agent (K-1) 3 × 10 ^-4 mol / m ²

[0069]

Embedded image

(Second photosensitive layer composition) Silver halide particle powder described in Tables 2 and 4 Organic silver salt flake described in Tables 2 and 4 Hydrazide compound described in Tables 2 and 4 Vinyl compound described in Tables 2 and 4 Binder (PVB-1) ) 2.6 g / m ² sensitizing dye (SD-1) 2 × 10 exits ^-5 mol / m ² antifoggant -1 (pre) 0.3 mg / m ² antifoggant-2 (supra) 1 0.2 mg / m ² reducing agent (K-1) 3 × 10 ^-4 mol / m ² (surface protective layer composition) Cellulose acetate butyrate 1.2 g / m ² Phthalazine 0.2 g / m ² 4-methylphthalic acid 0 .7g / m ² tetrachlorophthalic acid 0.2 g / m ² tetrachlorophthalic anhydride 0.5 g / m ² was thus prepared samples 101-136.

[0071]

[Table 1]

[0072]

[Table 2]

[0073]

[Table 3]

[0074]

[Table 4]

The photographic performance of each sample was evaluated. << Evaluation of photographic performance >> The prepared sample was subjected to 25 ° C. and 48% RH
After storing for 3 days in an atmosphere of (relative humidity), 810 n
120 ° C after exposure with a sensitometer for semiconductor laser exposure
Heating and development for 8 seconds, fog, sensitivity,
The highest density ( _Dmax ) was determined.

As the image preserving property, 40 ° C./48% R
The fog value when left in the room H for 30 days was evaluated.
The sensitivity was represented by the reciprocal of the exposure amount giving a density of 0.3, and was represented by a relative sensitivity with the reference being 100. The laser exposure was set to a single mode with an incident angle of 90 degrees.

The results are shown in Tables 5 and 6.

[0078]

[Table 5]

[0079]

[Table 6]

In Tables 5 and 6, * 1 represents the content ratio of silver halide grains in the photosensitive layer per m ² (second
* 2 is the content ratio of hydrazide compound in the photosensitive layer per 1 m ² (first photosensitive layer / second photosensitive layer), * 3 is the ratio of vinyl compound in the photosensitive layer. The content ratio per 1 m ² (first photosensitive layer / second photosensitive layer) is shown.

As can be seen from Tables 5 and 6, the photosensitive silver halide grains having an average grain size according to the present invention were used, and the content of the silver halide grains in the second photosensitive layer was made larger than that in the first photosensitive layer. ,
It can be seen that when the content of the hydrazide compound or vinyl compound in the first photosensitive layer is larger than that in the second photosensitive layer, a photothermographic material excellent in fog, sensitivity, maximum density and storage stability can be obtained. When the silver halide grains are sensitized with the chemical sensitizer of the present invention, high sensitivity is obtained, the maximum density is high, and the storage stability is good.

Example 2 Samples 101, 116, 126 and 130 similar to those of Example 1
And 134 were produced, and the images after exposure and development were evaluated. Here, a method of exposing by changing the incident angle of laser exposure, a laser beam divided into two and a path length of 20 to 100 n were used.
A double beam exposure method of combining and exposing again with a difference of m ± 3 nm was performed, and an exposure method at a wavelength in which a high frequency of 1 MHz was superimposed was performed.

The results are shown in Tables 7 and 8. The evaluation of interference unevenness was performed by visually evaluating interference unevenness at an optical density of 1.0 on the basis of the following five criteria.

5: Level with no unevenness 4: Level where slight unevenness is visible 3: Level where unevenness is visible but practically no problem 2: Level where unevenness is quite visible 1: Level where unevenness is strongly visible

[0085]

[Table 7]

[0086]

[Table 8]

From these results, it can be seen that, when exposing the photothermographic material of the present invention, the incident angle is changed and the angle is preferably between 55 and 88 degrees. Further, it can be seen that the light scattering of the fine particles is reduced by the double beam exposure or the exposure of the high frequency superimposition, the interference unevenness is reduced and the image quality is improved.

[0088]

By using the photothermographic image forming material of the present invention, which has low fog, high sensitivity and high density, and is excellent in image storability, interference unevenness hardly occurs and a uniform development finish can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03D 13/00 G03D 13/00 H

Claims (7)

[Claims] An average particle size of 20 to 80 n on a support.
m, a photosensitive layer comprising a photosensitive layer containing photosensitive silver halide grains, an organic silver salt, a reducing agent and a binder. A second photosensitive layer adjacent to the photosensitive layer, wherein the content of the photosensitive silver halide grains is such that the first photosensitive layer <the second photosensitive layer, the hydrazide compound in the photosensitive layer, and the electron-withdrawing group in the molecule. Content of the vinyl compound having the first photosensitive layer>
A photothermographic image forming material, which is a second photosensitive layer. 2. The photothermographic image forming material according to claim 1, wherein the photosensitive silver halide grains in the second photosensitive layer are chemically sensitized with an unstable sulfur or selenium compound. 3. The photothermographic image forming material according to claim 1, wherein at least one of the photosensitive silver halide grains in the photosensitive layer is heat-treated in the presence of an oxidizing agent. 4. The hydrazide compound, wherein at least one of the —NHNH— groups has a group selected from a benzoyl group, a phenyl group and a triphenylmethyl group which may have a substituent. The photothermographic image forming material according to claim 1. 5. The vinyl compound having an electron-withdrawing group has an electron-donating group at the same time.
4. The photothermographic image forming material according to any one of the above items 3. 6. A scanning laser beam for recording an image on the photothermographic image forming material according to claim 1, wherein the scanning laser beam is a double beam having the same wavelength and different incident angles. Characteristic image forming method. 7. A scanning laser beam for recording an image on the photothermographic image forming material according to any one of claims 1 to 5, wherein the scanning laser beam is an exposure by a laser beam scanning exposure device which is a vertical multi. Image forming method.