JP2002122959A - Heat developable material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat developable material which ensures high sensitivity and low fog, improves heat resistance (the rise of fog density) and light resistance (the lowering of maximum density) after development and has superior image preservability. SOLUTION: In a heat developable material with a photosensitive layer containing photosensitive silver halide grains, an organic silver salt, a reducing agent and a binder and a layer adjacent to the photosensitive layer on the base, 1 a polyhalomethane compound having a phosphazene nucleus in its molecule is incorporated into at least one of the layers. 2 In the above item 1, a polyvinyl acetate derivative or a poly(meth)acrylic acid derivative is used as the binder. 3 In the above items 1 and 2, a phthalazin compound is further used. 4 In the above items, the binder is applied in the presence of a crosslinker.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-developable material for forming an image by heat development, and more particularly to a heat-developable material capable of obtaining high sensitivity and low fog, and improving light resistance and fog density after development or lowering the maximum density. The present invention relates to a heat-developable material which is suppressed and has excellent image preservability.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for photothermographic materials which do not generate waste liquid due to wet processing from the viewpoints of environmental protection and workability in the fields of medical treatment and printing. Technologies relating to photothermographic materials for photographic technology capable of forming images have 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 light-sensitive materials which are liquid-developed in the range of 25 ° C. to 45 ° C. and are called heat developing materials.

Conventionally, a heat developing material of this type has a photosensitive layer containing high-sensitivity silver halide grains spectrally sensitized with a dye, an organic silver salt, and a reducing agent, and light irradiated toward the photosensitive layer. An anti-irradiation layer (A) that prevents light from passing through without being absorbed and being irregularly reflected at the interface of the support, the intermediate layer, the adhesive layer, and the like.
I) or a backing layer (B
C), and a protective layer is provided on the photosensitive layer and the BC layer to prevent scratches during handling.

Generally, a heat-developable material is easy to process because an image is formed only by heat development after exposure, but it is important to improve the storability of the image after development because there is no fixing step. I have. In order to improve image storability after development, it is good to develop the image at a high temperature so that an image appears. However, if the development temperature is too high, fogging is likely to occur and the sensitivity is lowered. Therefore, development is generally performed at a temperature around 120 ° C. ± 10 ° C.

The use of a mercapto compound to reduce fog is disclosed in JP-A-63-301037, JP-A-5-341432, JP-A-5-509182, and
No. 00-19681. But,
All of these mercapto compounds have little effect of suppressing fog, and it is difficult to obtain high sensitivity, and there is a limit in improving storage stability.

A polyhalomethane compound has been proposed as a fogging inhibitor for a heat-developable photosensitive material because it can release halogen radicals by light or thermal excitation to reduce fog. For example, U.S. Pat. Nos. 3,874,946, 4,452,885, 4,546,075, 4,756,999, 5,340,712, and JP-B-54-165. And JP-A-50-137126, JP-A-7-2781, JP-A-9-265150, and JP-B-2-32614. However, the polyhalomethane compounds disclosed therein have the following
Mainly one to three polyhalomethane substituents in the molecule,
It cannot be said that fog reduction due to the release of halogen is sufficiently high. Various chemical structures have been devised for the group bonded to the polyhalomethane group in order to enhance the halogen releasing effect, but it cannot be said that sufficient performance has yet been obtained. This is because sensitivity is often lowered when the ability to release halogen radicals is high, and when the ability to release halogen radicals is small, it is difficult to suppress fog and improve image storability.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-developable material having high sensitivity and low fog in photographic performance, and a heat-developable material having excellent image storability after heat development. To provide.

[0008]

The above object is achieved by the following (1).
(5).

(1) A photosensitive layer containing photosensitive silver halide grains, an organic silver salt, a reducing agent and a polymer binder on a support, and an adjacent layer adjacent to the photosensitive layer and containing a polymer binder Wherein at least one of the photosensitive layer and the adjacent layer contains a polyhalomethane compound having a phosphazene nucleus in a molecule.

(2) The heat-developable material as described in (1) above, wherein the polyhalomethane compound is represented by the general formula (M).

(3) As a polymer binder in at least one of the photosensitive layer and the adjacent layer, a polyvinyl acetate derivative;
The heat-developable material according to the above (1) or (2), comprising a polyacrylic acid derivative or a polymethacrylic acid derivative.

(4) The heat-developable material as described in (1), (2) or (3) above, wherein at least one of the photosensitive layer and the adjacent layer further contains a phthalazine compound.

(5) The polymer binder in at least one of the photosensitive layer and the adjacent layer is cross-linked by a cross-linking agent selected from compounds having an isocyanate group, an alkoxysilane group, a vinylsphone group or a carbodiimide group. The heat developing material according to the above (1), (2), (3) or (4), which is characterized in that:

The present invention is directed to a heat development method having a photosensitive layer containing photosensitive silver halide grains, an organic silver salt, a reducing agent and a polymer binder, and an adjacent layer adjacent to the photosensitive layer and containing a polymer binder. This problem has been solved by including a polyhalomethane compound having a phosphazene nucleus in a molecule in at least one of the photosensitive layer and an adjacent layer of the photosensitive layer, and the polyhalomethane compound further comprises phthalazine By using in combination with the compound, the image storability after thermal development can be further improved,
The inventors have found that the image storage stability can be further improved by crosslinking the polymer binder contained in the photosensitive layer of the heat-developable material or the layer adjacent thereto with the crosslinking agent, thereby achieving the present invention.

It is well known that a compound having a phosphazene nucleus is contained in a polyester resin, a polyolefin resin, a vinyl chloride resin or the like, and it is considered that it is difficult to contain the compound in the polymer binder of the present invention. Although it has been considered that the compound having a phosphazene nucleus can be dispersed and contained in the polymer binder of the present invention by polyhalomethane conversion, and it is considered that it depends on the molecular structure. The present invention is based on the finding that the reaction is suppressed at a low temperature without deterioration and has an effect of improving the image storability, and such an effect is unexpectedly obtained.

Further, a phthalazine compound is known as a toning agent in a heat-developable material and can change the brown color of heat-developable silver to a black tone in the present invention. By using in combination with the compound, fog is suppressed,
It was not expected to have a combined effect of improving sensitivity and image storability.

Hereinafter, the present invention will be described in detail. The polyhalomethane compound having a phosphazene nucleus used in the present invention in a molecule (hereinafter referred to as “polyhalomethane compound of the present invention”) is obtained by directly adding a polyhalomethane group to a phosphazene nucleus having a so-called cyclotriphosphazene structure having a 6-membered ring skeleton. Or a compound bound indirectly, for example, 2,
It is a compound having a structure obtained by directly or indirectly bonding a polyhalomethane substituent to 2,4,4,6,6-hexachloro-1,3,5-cyclotriphosphazene. The polyhalomethane compound of the present invention is preferably represented by the general formula (M). In the formula, the bonding group represented by L is, for example, -NHCO-, NHSO _2- ,

[0018]

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And the like. Preferred specific examples of the polyhalomethane compound of the present invention are shown below, but are not limited thereto.

[0020]

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[0021]

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[0022]

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In the method for synthesizing the polyhalomethane compound of the present invention, the method for synthesizing the phosphazene nucleus can be referred to US Pat. No. 3,370,020.
The method of polyhalomethanation is described in US Pat.
No. 46, No. 4,452,885, No. 4,546,07
No. 5, each specification and the like can be referred to.

The polyhalomethane compound of the present invention may be contained in at least one of the photosensitive layer and the layer adjacent thereto, but is preferably contained in at least the photosensitive layer.

The polyhalomethane compound of the present invention can be used in an organic solvent such as alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone and acetone, aromatic solvents such as toluene and xylene, and non-aromatic solvents such as normal hexane and decane. It may be added by dissolving it, may be dispersed in water, or may be directly added as a powder or tablet. The used amount can be in the range of 10 ^-6 to 10 ^-2 mol per mol of silver halide. If the amount is less than this range, the effect of improving the image storability intended by the present invention is difficult to be obtained, and if the amount exceeds this range, it becomes unfavorable because of softness or weak coating.

It is preferable to use a phthalazine compound in combination with the polyhalomethane compound of the present invention. The phthalazine compound used in the present invention means phthalazine and a compound obtained by introducing various substituents into a phthalazine ring.
The phthalazine compound preferred in the present invention is a compound having the following substituent introduced into the phthalazine ring.

Examples of the substituent include a halogen atom, a cyano group, a hydroxy group, an optionally substituted alkyl group, an alkenyl group, an alkynyl group, an alkoxy group,
An aromatic group, a heterocyclic group and the like. The alkyl group, alkenyl group, alkynyl group, and alkoxy group each preferably have 1 to 60 carbon atoms, particularly preferably 1 to 40 carbon atoms. When the number of carbon atoms exceeds 60, good effects on fog suppression, color tone and storage stability cannot be obtained. The substitution position of the above substituent may be 1 except for the 2-position and 3-position of the phthalazine ring.
Substituents can be introduced at positions from position 8 to position 8.

Specific examples of the phthalazine compound used in the present invention are shown below, but the present invention is not limited thereto.

(F1) phthalazine (f2) 6-aminophthalazine (f3) 5-methylphthalazine (f4) 6-chlorophthalazine (f5) 6-isopropylphthalazine (f6) 6- (4,6-tert) -Amylphenyl)
Phthalazine (f7) 6-phenylphthalazine (f8) 6-methoxyphthalazine (f9) 1,4-dimethylphthalazine (f10) 5,6-dimethoxyphthalazine (f11) 6-isobutylphthalazine In the present invention, phthalazine The compound may be dissolved in an organic solvent such as an alcohol such as methanol or ethanol, a ketone such as methyl ethyl ketone or acetone, or an aromatic solvent such as toluene or xylene or a non-aromatic solvent such as normal hexane or decane. Good, can be dispersed in water,
Powders or tablets may be added directly. The used amount can be in the range of 10 ^-6 to 10 ^-2 mol per mol of silver halide. If the amount is less than this range, it is difficult to obtain the effect of improving the image storability of the present invention, and if the amount exceeds this range, it becomes unfavorable because of softness or weak coating.

Next, photosensitive silver halide grains, organic silver salts, reducing agents, binders, cross-linking agents, and other materials used in the heat-developable material of the present invention will be described in order.

The photosensitive silver halide grains contained in the photosensitive layer of the heat-developable material of the present invention 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, in an ammonia emulsion emulsion. It can be prepared in advance by any method such as a sexual method and an acidic method, and then mixed with other components of the present invention and introduced into the composition used in the present invention. In this case, in order to sufficiently contact the photosensitive silver halide particles with the organic silver salt, for example, US Pat. Nos. 3,706,564 and 3,706,565
No. 3,713,833, No. 3,748,14
No. 3, British Patent No. 1,362,970, means for using a polymer other than gelatin such as polyvinyl acetal, and British Patent No. 1,354,186.
Means for enzymatically degrading the gelatin of a light-sensitive silver halide emulsion as described in U.S. Pat.
As described in Japanese Patent Application No. 076,539, 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 grains preferably have a small grain size in order to suppress white turbidity after image formation and to obtain good image quality. 0.1 in average particle size
μm or less, preferably 0.01 to 0.1 μm, particularly 0.1 μm.
02 to 0.08 μm is preferred. There is no particular limitation on the shape of the silver halide grains, and cubic or octahedral so-called normal crystals or non-normal crystals such as spherical, rod-shaped, or tabular grains can be used. 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 grains is suitably not more than 50% by mass, preferably from 25 to 0.1% by mass, more preferably from 15 to 0% by mass, based on the total mass of the silver halide and the organic silver salt. .1% by mass. As the photosensitive silver halide grains, a part of the organic silver salt may be converted to silver halide by using a silver halide forming component, and various conditions such as a reaction temperature, a reaction time, and a reaction pressure in this step are as follows. The reaction temperature can be appropriately set in order to minimize energy consumption during production. Usually, the reaction temperature is −23 ° C. to 74 ° C., the reaction time is 0.1 second to 72 hours, and the reaction pressure is atmospheric pressure. Is preferably set to.

The photosensitive silver halide grains 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, a tin compound, a chromium compound or a combination thereof. can do. The method and procedure of the chemical sensitization are described in, for example, U.S. Pat.
No. 22430, No. 51-78319, No. 51-81
No. 124 and other publications.

In the present invention, the photosensitive silver halide grains can be sensitized with a spectral sensitizing dye, if necessary, and as the spectral sensitizing dye, for example, JP-A-63-159814.
No., 60-140335, 63-231437
No., 63-259,651 and 63-304242
Nos. 63-15245, U.S. Pat.
Nos. 6,39,414, 4,740,455, 4,741,966, 4,751,175, 4,835,096 and the like. Sensitizing dyes can be used. Sensitizing dyes useful in the present invention include, for example, Research Disclosure.
Item 17643 IV-A (p.2, December 1978)
3), Item 1831X (p.4, August 1978)
37) or in the literature cited. In particular, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of various scanner light sources can be advantageously selected. For example, compounds described in JP-A-9-34078, JP-A-9-54409 and JP-A-9-80679 are preferably used.

The organic silver salt contained in the heat-developable material of the present invention is a reducible silver source, and organic acids, heteroorganic acids and acid polymer silver salts containing a reducible silver ion source are used. . Also useful are organic or inorganic silver salt complexes in which the ligand has a total stability constant for silver ions of 4.0 to 10.0. Examples of organic silver salts are ResearchD
No. 17029 and 29996, and include the following: salts of organic acids (eg, salts of gallic acid, oxalic acid, behenic acid, stearic acid, palmitic acid, lauric acid, etc.) and the like.

The reducing agent contained in the heat-developable material of the present invention reduces an organic silver salt to form a silver image. Examples of preferred reducing agents are described in U.S. Pat. Nos. 3,770,448, 3,773,512, and 3,593,863, and Research Disclosure.
17029 and 299963, and specific examples include the following. (K1) 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane (K2) bis (2-hydroxy-3-tert-butyl-5-methylphenyl) methane (K3) 2,2-bis (4-hydroxy-3-methylphenyl) propane (K4) 4,4-ethylidene-bis (2-tert-butyl-6-methylphenol) (K5) 2,2-bis ( 3,5-Dimethyl-4-hydroxyphenyl) propane The reducing agent is dispersed in water or dissolved in an organic solvent to be contained in a coating solution for a photosensitive layer or a coating solution for an adjacent layer, and contained in these layers. be able to. 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 the reducing agent used is suitably in the range of 1 × 10 ^-2 to 10 mol per mol of silver,
Preferably it is 1 × 10 ^{-2 to} 1.5 mol.

As the polymer binder for the photosensitive layer of the heat-developable material of the present invention and the layer adjacent thereto and other non-photosensitive layers, a colorless transparent or translucent polymer binder is usually used. Polymer binders include polyvinyl butyral, polyacrylamide, polystyrene, polyvinyl acetate, polyurethane, polyacrylate, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, vinyl chloride-vinyl acetate copolymer, styrene -Butadiene-acrylic copolymer.

In the present invention, it is preferable to use a polyvinyl acetate derivative, a polyacrylic acid derivative or a polymethacrylic acid derivative as the binder.

In the present specification, a polyvinyl acetate derivative means a polymer (including a copolymer) having a monomer unit of vinyl acetate or a derivative thereof, and a polyacrylic acid derivative means acrylic acid. Or a polymer having an acrylic acid ester monomer unit (including a copolymer), and a polymethacrylic acid derivative is a polymer having a methacrylic acid or methacrylic acid ester monomer unit ( Including copolymers).

In the present invention, at least 70% of the total binder contained in each layer of the photosensitive layer and the adjacent layer.
The mass% is preferably a polyvinyl acetate derivative, a polyacrylic acid derivative or a polymethacrylic acid derivative.

The copolymer component of the vinyl acetate derivative or the poly (meth) acrylic acid derivative is a linear, branched or cyclic alkyl ester having 1 to 12 carbon atoms which may have a substituent of acrylic acid and methacrylic acid. The copolymerization ratio is preferably from 0 to 50 mol% in the case of a polyvinyl acetate derivative, and preferably from 80 to 99.9 mol% in the case of a poly (meth) acrylic acid derivative. 100 ~
It is preferably 3000, and particularly preferably in the range of 200 to 2000.

The binder used in the present invention is preferably one having a low equilibrium water content of the coating film after drying to form a film, and particularly having a low water content, for example, an organic solvent-based cellulose acetate, Mention may be made of cellulose acetate butyrate and polyacetal.

Polyacetal is a polymer obtained by producing polyvinyl alcohol by saponifying polyvinyl acetate and reacting the polyvinyl alcohol with an aldehyde compound. Polyacetal is obtained by reacting polybutyral and acetaldehyde acetalized with butyraldehyde. Acetalized polyacetals (polyacetals in a narrow sense) are preferred. Preferred polyacetals for the present invention are
The degree of saponification of polyvinyl acetate is 60 to 99.9%, and acetalization is theoretically present up to 1% to 100%, but practically preferably 20% to 95%. If the degree of acetalization is low, the number of hydroxyl groups is increased, and the photographic performance is weak against humidity. If the degree of acetalization is high, the reaction temperature and time are severe, and the cost and productivity are reduced. For water-based coatings, copolymers of styrene and butadiene as water-dispersed polymers, copolymers of styrene and alkyl acrylates or alkyl methacrylates, and copolymers of alkyl acrylates and alkyl methacrylates Can be mentioned. Further, as the above-mentioned water-dispersed polymer, it is preferable to use fine particles having an average particle diameter in the range of 1 nm to several μm and dispersed in an aqueous dispersion medium. The water-dispersed polymer is particularly preferably hydrophobic because it can improve water resistance while being widely used as a binder for aqueous coating. The degree of polymerization of the polymer can be freely selected from about 10 to about 10,000, but 100 to 6000 is preferable from the viewpoint of applicability and productivity in synthesis.

The binder alone forms the respective layers of the heat-developable material, thereby maintaining the adhesion to the lower layer and the upper layer and imparting a film strength that is hardly damaged. However, the use of a crosslinking agent further increases the film strength. Adhesion and film strength can be increased. Preferred crosslinking agents for the present invention are those having an alkoxysilane group, an isocyanate group, an epoxy group (glycidyl group), a vinylsulfonyl group or a carbodiimide group. Particularly preferred crosslinking agents are those having at least two isocyanate groups and those having at least two carbodiimide groups.
Carbodiimide crosslinking agents having at least two vinyl sulfonyl groups, alkoxysilane crosslinking agents having at least two alkoxy groups, and vinylsulfonyl crosslinking agents having at least two vinylsulfonyl groups. Examples of preferred crosslinking agents are shown below.

(H1) hexamethylene diisocyanate (H2) trimer of hexamethylene diisocyanate (H3) tolylene diisocyanate (H4) phenylene isocyanate (H5) xylylene diisocyanate (H6) 1,3 -Bis (isocyanatomethyl) cyclohexane (H7) tetramethylene xylylene diisocyanate (H8) m-isopropenyl α, α-dimethylbenzyl isocyanate (H9) phenylaminopropyltrimethoxysilane (H10) p-methylphenylpropyltrimethoxy Silane (H11) Dimethylaminopropyltrimethoxysilane (H12) Diethoxyaminopropyltriethoxysilane (H13) 1,3-bis (vinylsulfonamido) propane (H14) 1,2-bis (vinyl) Suhon'amido) ethane (H15) 1,3-bis (vinyl scan Hong) -2-
Hydroxypropane (H16) bis (vinylsulfonamide) ether

[0047]

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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 added as a solid to 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.

The heat-developable material of the present invention may have either a form in which the photosensitive layer is provided on only one side of the support or a form in which the photosensitive layer is provided on both sides. When the photosensitive layer is provided only on one side of the support, a form having a BC layer (backside layer) provided on the opposite side of the photosensitive layer and, in some cases, a protective layer thereof is included. The layer adjacent to the photosensitive layer is, for example, an irradiation prevention layer (AI layer) below the photosensitive layer and a protective layer above.

The heat-developable material of the present invention is provided with an AI layer for preventing irradiation of the heat-developable material and / or a BC layer for preventing halation of the heat-developable material, if necessary.
The dye used in the C layer may be any dye that absorbs image exposure light, and is preferably US Pat.
A heat-decolorable dye described in, for example, Japanese Patent No. 237 is used. If the dye is not heat-decolorable, the amount used is limited to a range that does not cause image damage to the heat-developable material, but if it is a heat-decolorable dye, it is necessary to add a sufficient amount of the dye. it can.

The heat-developable material of the present invention can be provided with a protective layer. The protective layer preferably contains a matting agent. The matting agent may be any of an organic substance and an inorganic substance. Examples of the inorganic matting agent include Swiss Patent No. 3
Silica described in US Pat. No. 30,158, Swiss Patent No. 3
No. 30,158, polystyrene or polymethacrylate; U.S. Pat. No. 3,079,257, polyacrylonitrile; U.S. Pat.
A matting agent composed of polycarbonate or the like described in Japanese Patent No. 22,169 can be used.

The shape of the matting agent may be either regular or irregular, but is preferably regular and spherical. The size of the matting agent is represented by a diameter when the volume of the matting agent is converted into a sphere. When the particle size of the matting agent is represented by a spherical converted diameter, the matting agent used in the present invention preferably has an average particle size of 0.5 to 10 μm, more preferably 1.0 to 8.0 μm. . Further, the matting agent has a coefficient of variation of the particle size distribution of preferably 50% or less, more preferably 40% or less, and particularly preferably 20% or less. The method for adding the matting agent may be a method in which the matting agent is dispersed in a coating solution in advance, or a method in which the matting agent is sprayed after the coating solution is applied and before the drying is completed.

As a support for the heat-developable material of the present invention,
Supports such as paper, synthetic paper, nonwoven fabric, metal foil, and plastic film can be used, and a composite sheet obtained by combining these can be used arbitrarily.

The method of exposing the heat-developable material of the present invention is optional. As the exposure method, for example, Japanese Patent Application Laid-Open No. 9-304869
No. 9-311403 and JP-A-2000-1023
Exposure with a laser can be carried out by the method described in each of the publications.

As the apparatus for developing the heat developing material of the present invention, a known apparatus can be used. For example, JP-A-11-
Nos. 65067, 11-72897 and 84619
The devices described in the above publications can be used.

[0056]

EXAMPLES Examples of the present invention will be described below, but embodiments of the present invention are not limited thereto.

Example 1 << Preparation of Subbed Substrate >> A polyethylene terephthalate support having a thickness of 175 μm was subjected to a corona discharge treatment of 12 W / m ² · min on both sides, and the following subbing coating solution a- 1
Is applied to a dry film thickness of 0.6 μm and dried to form an undercoat layer A-1.
-1 was applied to a dry film thickness of 0.6 μm and dried to form an undercoat layer B-1. (Subbing coating solution a-1) Copolymer latex liquid of butyl acrylate (30% by mass), t-butyl acrylate (20% by mass), styrene (25% by mass), 2-hydroxyethyl acrylate (25% by mass) (Solid content 30
% Liquid) (undercoating coating solution b-1) A copolymer latex liquid of butyl acrylate (40% by mass), styrene (20% by mass), and glycidyl acrylate (40% by mass) (solid content 30%)
%) Diluted 15-fold. Subsequently, on the upper surface of the undercoat layer A-1 and the undercoat layer B-1,
By applying a corona discharge of 12 W / m ² · min, the following undercoating layer A-1 is coated and dried on the undercoating layer A-1 to form an undercoating layer A-2. -1 was coated with an undercoating layer coating solution b-2 described below and dried to form an undercoating layer B-2 having an antistatic function. (Undercoating upper layer coating solution a-2) 1: 2 (mass ratio) copolymer of styrene and butadiene 0.4 g / m ² silica particles (average particle size 3 μm) 0.05 g / m ² (undercoating upper layer coating solution) b-2) of styrene and butadiene 1: 2 ( "Preparation of photosensitive layer coating solution" mass ratio) copolymer 0.4 g / m ² tin oxide fine particles (average particle size 16 nm) 0.023 g / m ² (halogenated Preparation of Silver Particle Emulsion A) After dissolving 7.5 g of inert gelatin and 10 mg of potassium bromide in 900 ml of water and adjusting the temperature to 28 ° C. and the pH to 3.0, 370 ml of an aqueous solution containing 74 g of silver nitrate and (98/2) Aqueous solution containing a molar ratio of potassium bromide and potassium iodide in an equimolar amount to silver nitrate was added over 10 minutes by a controlled double jet method while maintaining pAg 7.7. Synchronously with the addition of silver nitrate, sodium salt of hexachloroiridium was added at 10 ^-6 mol / mol of silver. Thereafter, 0.3 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, the pH was adjusted to 5 with NaOH, the average particle size was 0.036 μm, and the variation coefficient of the projected diameter area was 8
%, And a [100] face ratio of 87% were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant and desalting treatment, and then water was added to make up to 160 ml. (Preparation of water-dispersed organic silver salt) Behenic acid (111.4 g), arachidic acid (83.8 g), and stearic acid (54.9 g) were dissolved in 3980 ml of pure water at 80 ° C. Next, while stirring at high speed, 540.2 m of a 1.5 mol aqueous sodium hydroxide solution
After adding 6.9 ml of concentrated nitric acid, the mixture was cooled to 55 ° C. to obtain a sodium organic acid solution. While maintaining the temperature of the organic acid sodium acid solution at 55 ° C., the silver halide grain emulsion A (containing 0.038 mol of silver) and pure water 420
ml was added and stirred for 5 minutes. Next, 760.6 ml of a 1 mol silver nitrate solution was added over 2 minutes, the mixture was further stirred for 20 minutes, and water-soluble salts were removed by filtration. Thereafter, the filtrate was repeatedly washed with deionized water and filtered until the conductivity of the filtrate reached 2 μS / cm, and finally dried after centrifugal dehydration. << Coating on the photosensitive layer side >> The following layers were sequentially formed on the support provided with the undercoat layer to prepare a heat development material sample. The drying was performed at 45 ° C. for 1 minute. (AI layer coating composition) Binder: 0.4 g / m ² C1 (dye) described in Table 1 1.2 × 10 ⁻⁵ mol / m ² Polyhalomethane compound: described in Table 1 1.0 × 10 ⁻⁴ mol / m ² For the formation of the photosensitive layer, a coating solution of the following composition was prepared, and was applied and dried so as to have the following amount. 1.3 as silver
An amount of the organic silver salt preparation of 6 g / m ² was mixed with the polymer binder.

Binder: described in Table 1 2.6 g / m ² polyhalomethane compound: described in Table 1 3.2 × 10 ⁻⁴ mol / m ² Spectral sensitizing dye A1 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: Exemplified compound K1 3.3 mmol / m ² (surface protective layer) The surface protective layer was formed by coating and drying on the photosensitive layer so that the following amount was obtained.

Cellulose acetate butyrate 1.2 g / m ² 4-methylphthalic acid 0.7 g / m ² Tetrachlorophthalic acid 0.2 g / m ² Tetrachlorophthalic anhydride 0.5 g / m ² Silica matting agent (average 0.5 g / m ² polyhalomethane compound: described in Table 1 1.0 × 10 ⁻⁴ mol / m ^{2 As} the binder, use was made of two kinds of polyacetal and a copolymer of styrene and butadiene. In the case of (1), methyl ethyl ketone (MEK) was used as the organic solvent, and the styrene-butadiene copolymer was formed by aqueous coating in which additives were dispersed in fine particles. The polyacetal was prepared by saponifying 98% of polyvinyl acetate having a polymerization degree of 500 and then butyralizing 86% of the remaining hydroxyl groups (hereinafter referred to as “PVB-1”). The copolymer of styrene and butadiene was prepared by emulsion copolymerization of styrene and butadiene by a conventional method with a mass composition ratio of 1: 2 (“SB
-1 "). The compound 5 (T1 described below) used in Example 7 of JP-B-2-32614 was used as a comparative polyhalomethane compound. << Coating on BC Layer >> On the back surface side, each coating solution for the BC layer and its protective layer prepared so as to have the following composition was applied and dried to form the BC layer and the protective layer. (BC layer composition) PVB-1 (binder) 1.8 g / m ² C1 (dye) 1.2 × 10 ⁻⁵ mol / m ² (BC protective layer coating solution) Cellulose acetate butyrate 1.1 g / m ² Matting agent (PMMA: average particle diameter 5 μm) 0.12 g / m ²

[0060]

Embedded image

<< Evaluation >> (Photo Performance) The heat-developable material sample prepared above was divided into three, and one of them was stored at 25 ° C. in an atmosphere of 48% relative humidity for 3 days, and then exposed to an 810 nm semiconductor laser. A sample obtained by exposing with a sensitometer and heating at 120 ° C. for 8 seconds after the exposure was used as an immediate sample (processing is referred to as “immediate processing”). The second sample was exposed with a laser exposure sensitometer in the same manner as the first sample, and the test sample after development was allowed to stand on a 1000 lux Sharksten for 10 hours.
x, light resistance test among image storability) were measured. The third sample was exposed with a laser exposure sensitometer in the same manner as the first sample, developed, and then stored in a dark room at 55 ° C. and a relative humidity of 20% for 3 days (heat resistance in image storability). ) Was measured. The laser exposure and development processing of the normal humidity sample were performed in a room conditioned at 25 ° C. ± 1 ° C. and a relative humidity of 48% ± 1%.

The sensitivity and fog of the above immediate sample and image storage test sample were measured with a densitometer. The sensitivity is evaluated by the reciprocal of the ratio of the exposure amount that gives a density 0.3 higher than the fog density, and expressed as a relative evaluation using the sample 101 as a reference (100). It was expressed by the difference and the decrease of the highest concentration in the light fastness test. The smaller the increase value of the fog or the decrease value of the maximum density, the better the image storability. Table 1 shows the results.

[0063]

[Table 1]

(Note) In Table 1, "PHM" means a polyhalomethane compound. From Table 1, it was found that the sample using the polyhalomethane compound of the present invention, while using the polyhalomethane compound for comparison, had the highest density at which photographic performance (sensitivity and fog) and image preservability (light fastness) during thermal development were obtained. It can be seen that the decrease in image quality and the increase in fog, which is the image storage stability (heat resistance), are small.

Example 2 A sample was prepared and its performance was evaluated in the same manner as in Example 1, except that a polyhalomethane compound and a phthalazine compound (PT
Z) was added to the AI layer, photosensitive layer and protective layer in the following amounts, and tested for image storability.

Addition amount PHM: Addition amount of AI layer, photosensitive layer and protective layer is the same as in Example 1. PTZ: AI layer 1 × 10 ^-4 mol / m ² Photosensitive layer 2 × 10 ^-4 mol / m ² Protection Layer 1 × 10 ⁻⁴ mol / m ^{2 The} relative sensitivity was calculated with the sample number 201 as 100.

The results are shown in Table 2 below.

[0068]

[Table 2]

From Table 2, it can be seen that when a phthalazine compound is used in combination with the polyhalomethane compound of the present invention, the fog of immediate processing and the increase in sensitivity and image storage stability (heat resistance) are small, and the image storage stability (light resistance) is the highest. It can be seen that the decrease in concentration is small.

Example 3 A heat-developable material sample was prepared in the same manner as in Example 1. In this example, a crosslinking agent containing a polyhalomethane compound was used.
Added to I layer, photosensitive layer or protective layer. In the photosensitive layer,
2.8 × 10 ^-4 mol / m ^{2 was} added, and 0.8 was added to the protective layer.
× 10 ^-4 mol / m ^2, the AI layer 0.9 × 10 ^-4 mol /
m ^{2 was} added. In addition, the same crosslinking agent was used in the same sample. Photographic performance and image storability were evaluated as in Example 1. The results are shown in Table 3 below.

[0071]

[Table 3]

From Table 3, it can be seen that when a phthalazine compound crosslinking agent is used in combination with the polyhalomethane compound of the present invention, image storability (heat resistance, ie, increase in fog, and light resistance, ie, decrease in maximum density) are improved.

[0073]

According to the present invention, a heat-developable material can be obtained in which high sensitivity and low fog are obtained by heat development, and the image storage properties (light resistance and heat resistance) after heat development are improved.

Claims (5)

[Claims] 1. A photosensitive layer containing photosensitive silver halide grains, an organic silver salt, a reducing agent and a polymer binder on a support,
A heat developing material having an adjacent layer adjacent to the photosensitive layer and containing a polymer binder, wherein at least one of the photosensitive layer and the adjacent layer contains a polyhalomethane compound having a phosphazene nucleus in a molecule. Heat developing material. 2. The heat developing material according to claim 1, wherein the polyhalomethane compound is represented by the following general formula (M). Embedded image Wherein each X is the same or different, represents chlorine or bromine, each L is the same or different, represents a linking group, each n is the same or different, 0 or 1 It is. 3. The polymer binder in at least one of the photosensitive layer and the adjacent layer contains a polyvinyl acetate derivative, a polyacrylic acid derivative or a polymethacrylic acid derivative. The heat-developable material as described above. 4. The photothermographic material according to claim 1, wherein at least one of the photosensitive layer and the adjacent layer further contains a phthalazine compound. 5. The method according to claim 1, wherein the polymer binder in at least one of the photosensitive layer and the adjacent layer is cross-linked by a cross-linking agent selected from compounds having an isocyanate group, an alkoxysilane group, a vinylsphone group or a carbodiimide group. 5. The heat-developable material according to claim 1, 2, 3, or 4.