JP2002107870A - Heat developable material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart an aptitude for the production and recycling of a base used in a heat developable material, to provide a heat developable material free of the deterioration of its photographic performance and having high sensitivity, low fogging and high sharpness and to provide a medical heat developable material which will not stain intensifying screen even after radiographing repeated many times. SOLUTION: In the heat developable material with a photosensitive layer, containing photosensitive silver halide grains, an organic silver salt, a reducing agent and a binder and a binder-containing layer adjacent to the photosensitive layer on the base with an undercoat layer, an anthraquinone dye, having a carboxyl or hydroxyl group, is fixed on a binder with a crosslinker in the undercoat layer or in the layer between the undercoat layer and the photosensitive layer.

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 expanding the suitability for production and recycling of a support to be used. The present invention relates to a heat-developable medical material having low fog, high sharpness, and free from intensifying screen stains.

[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 viewpoint of environmental protection and workability in the medical field. In particular, high-resolution and clear black images are formed by thermal development. Technologies relating to photothermographic materials for photographic technology that can be used are commercialized and rapidly spreading. 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.

[0003] Conventionally, this type of medical heat developing material has been
A photosensitive layer containing a highly sensitive silver halide particle spectrally sensitized with a dye, an organic silver salt and a reducing agent on a polyester support colored with a blue dye, and light irradiated toward the photosensitive layer is absorbed. Layer for preventing irregular reflection at the interface of the support, intermediate layer, adhesive layer, etc.
Layer) or a backing layer (BC) provided on the opposite side of the support.
And a protective layer is provided on the photosensitive layer and the BC layer to prevent scratches during handling. The use of the support colored with a blue dye is intended to make the silver image observed on the Schaukasten clear and easy to observe, but the use of the support is limited by coloring the support. There are disadvantages. The colored support may not be used for printing materials that require other transparency, or when using a used support, it may be difficult to distinguish between a non-colored support and a colored support. . There is a method such as coloring the undercoat or the layer between the photosensitive layer and the undercoat without coloring the support, or coloring the support slightly and using it together with the coloring of the undercoat layer or the layer between the photosensitive layer and the undercoat. . The problem with coloring in the undercoat layer and the layer between the undercoat layer and the photosensitive layer is that the dye used for coloring diffuses and moves to the photosensitive layer or the protective layer of the photosensitive layer. Fogging increases when diffused and moved to the photosensitive layer,
The sensitivity is reduced and sharpness is deteriorated. Further, when the dye is diffused to the protective layer, the dye is transferred to the intensifying screen in X-ray photography. The sensitivity is lowered due to the insufficient light quantity due to the light absorption by the dye, and when the transfer portion and the non-transfer portion are mixed, an image having unevenness is obtained. In order to prevent the transfer, it is necessary to fix the dye to the undercoat layer and the layer between the undercoat layer and the photosensitive layer. As a fixing method, there is a method in which a dye is dispersed in fine particles and fixed. The problem with the fine particle dispersion method is that if a dye that is not dispersed in any part is mixed, a large image defect will occur. In addition, there are disadvantages such as poor stagnation and preservation of the dye solution in which fine particles are dispersed. As time passes, problems such as aggregation and precipitation of the fine particles occur.
Therefore, it is better not to fix the particles but to chemically fix them to the binder. When gelatin is used as a hydrophilic binder, there is a method of immobilizing a dye on gelatin, but a heat-developable material in which no gelatin is used or the amount of gelatin used is within 30% by mass of the total binder is used. However, since a polymer having a low water content after drying is used, the immobilization is not as complete as that of gelatin. It is thought that when the fixation is complete, the sensitivity of the photographic performance decreases, the fog increases, the photographic performance during high-temperature storage decreases, the sharpness increases, the dye deteriorates less to light, and the light resistance improves. But no good way was found.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide the support with the suitability for production and recycling.
The aim of this optimization is to provide a high-sensitivity, low-fog, high-sharpness heat-developable material without deteriorating photographic performance. It is an object of the present invention to provide a heat-developable medical heat-free material.

[0005]

The above object of the present invention has been attained by the following constitutions.

[0006] 1. In a heat-developable material having a photosensitive layer containing photosensitive silver halide grains, an organic silver salt, a reducing agent and a binder on a support having an undercoat layer, and a layer adjacent to the photosensitive layer and containing a binder, A heat-developable material characterized in that an anthraquinone dye having a carboxyl group or a hydroxyl group is fixed to a binder with a crosslinking agent in a layer or in a layer between the undercoat layer and the photosensitive layer.

[0007] 2. 2. The heat-developable material according to item 1, wherein the crosslinking agent is a crosslinking agent having an isocyanate group, an alkoxysilane group, or a carbodiimide group.

[0008] 3. The photosensitive layer of the heat-developable material or a layer adjacent to the photosensitive layer has a binder made of polyacetal or a water-dispersible hydrophobic polymer, and the binder is cross-linked with the cross-linking agent described in the item 2. 1 or 2 above
2. The heat developing material according to 1.

4. 4. The heat-developable material as described in any one of the above items 1 to 3, wherein the binder used for the undercoat layer or the photosensitive layer of the heat-developable material is a polymer having a carboxyl group or a hydroxyl group.

[0010] 5. 5. The dye according to any one of 1 to 4, wherein the dye immobilized on the binder has an absorption maximum in the range of 580 nm to 680 nm, and the concentration at the absorption maximum is 0.05 to 0.5. 2. The heat developing material according to 1.

Hereinafter, the present invention will be described in detail. The heat-developable medical material of the present invention has at least one layer colored with a blue dye between an undercoat layer or an undercoat layer and a photosensitive layer,
Further, the photosensitive layer has at least two layers including a photosensitive layer and a layer adjacent to the photosensitive layer, and includes a BC layer provided on the opposite side of the photosensitive layer, and in some cases, a protective layer thereof.
The photosensitive layer of the heat-developable material contains photosensitive silver halide grains that may be sensitized with a spectral sensitizing dye, and the photosensitive layer or an adjacent layer thereof includes an organic silver salt serving as a silver source. A reducing agent for developing a silver salt to form a silver image is contained.

The blue dye used in the undercoat layer or the layer between the undercoat layer and the photosensitive layer of the heat-developable material of the present invention is a "compound having an anthraquinone nucleus having a carboxyl group or a hydroxyl group" (hereinafter referred to as AQH and AQH). Abbreviated), photosensitive silver halide grains, organic silver salts, reducing agents, binders, cross-linking agents, etc. will be further described later. The intermediate layer between the undercoat layer and the photosensitive layer may be an anti-irradiation (AI) layer containing a dye for preventing irradiation, or may be an applicability improving layer for improving applicability of the photosensitive layer. Although it may be a development control layer for improving the developability of the photosensitive layer, in the present invention, the AI layer will be described below irrespective of the presence of an irradiation inhibitor.

(AQH) AQH has an anthraquinone mother nucleus, and the structure referred to as the anthraquinone mother nucleus is a structure in which the 9th and 10th positions of anthracene are oxidized.
It can be referred to as 0-anthracenedione or 9,10-dioxoanthracene. Utilizing a functional group such as an amino group, a hydroxyl group or a carboxyl group, a vinyl group, an acid chloride group, and a halogen atom (chlorine, bromine or iodine) in the mother nucleus, a carboxyl group or a hydroxyl group and a substituent containing these groups are used. The compound introduced. A method for synthesizing an anthraquinone nucleus and a derivative thereof is disclosed in JP-A-6-0060.
No. 23, No. 6-097784, No. 9-176084
No. 11-502865, and the like. In the method of introducing a carboxyl group or a hydroxyl group into the mother nucleus, a substituent having a carboxyl group or a hydroxyl group may be introduced into the anthraquinone mother nucleus, or an alkyl group capable of being a carboxyl group, a cyano group,
Derivation may be performed after introducing an alkylcarboxy group.
The hydroxyl group may also be synthesized by introducing a halogenated hydroxyalkyl group or a halogenated hydroxyalkyloxy group.

AQH used in the present invention has an absorption maximum of 5
Within the range of 80 nm to 680 nm, but 600 to 6
Those having an absorption maximum of 40 nm are preferred.

Preferred examples of AQH used in the present invention are shown below, but are not limited thereto.

[0016]

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[0017]

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[0018]

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The AQH used in the present invention includes organic solvents 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. May be added by dissolving in water, may be dispersed in water,
Powders or tablets may be added directly. The used amount can be in the range of 10 ^-5 mol to 10 ^-2 mol per mol of silver halide. When the amount is within this range, the concentration at the absorption maximum obtained is 0.05 to 0.5. Preferably, it is 0.15 to 0.5.

Next, the organic silver salt, reducing agent, photosensitive silver halide particles, binder, cross-linking agent, mercapto compound and the like used in the heat developing material of the present invention will be described in order.

(Organic Silver Salt) The organic silver salt contained in the heat-developable material of the present invention is a reducible silver source, and an organic acid, a heteroorganic acid and an acid polymer containing a reducible silver ion source. Salts and the like are used. Further, when the ligand is 4.0 to 1
Organic or inorganic silver salt complexes having a total stability constant for silver ions of 0.0 are also useful. An example of a silver salt is Resea
rc Disclosure Nos. 17029 and 299
63 and includes: salts of organic acids (eg, salts of gallic acid, oxalic acid, behenic acid, stearic acid, palmitic acid, lauric acid, etc.) and the like.

(Reducing Agent) Examples of preferred reducing agents contained in the heat-developable material of the present invention are described in US Pat. No. 3,770,44.
No. 8, 3,773, 512, 3,593, 863
No., etc., and Research Disclo
Sure Nos. 17029 and 29996, and include:

K1: 1,1-bis (2-hydroxy-
3,5-dimethylphenyl) -3,5,5-trimethylhexane K2: bis (2-hydroxy-3-t-butyl-5-methylphenyl) methane K3: 2,2-bis (4-hydroxy-3- Methylphenyl) propane K4: 4,4-ethylidene-bis (2-t-butyl-6
-Methylphenol) K5: 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane The compound shown above 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 the reducing agent to be used is 1 × 10 ^-2 to 10 mol, preferably 1 × 10 ^-2 to 1 mol per mol of silver.
5 moles.

(Photosensitive Silver Halide Particles) The photosensitive silver halide contained in the photosensitive layer of the heat-developable material of the present invention is:
Any method known in the field of photographic technology such as a single jet or double jet method, for example, an ammonia method emulsion, a neutral method, prepared in advance by any method such as an acid method, and then mixed with other components of the present invention. It can be mixed and introduced into the composition used in the present invention. In this case, in order to sufficiently contact the photosensitive silver halide and the organic silver salt,
For example, US Pat. Nos. 3,706,564 and 3,7 as protective polymers for preparing photosensitive silver halide.
No. 06,565, No. 3,713,833, No. 3,
No. 748,143 and British Patent No. 1,362,970. Means using a polymer other than gelatin such as polyvinyl acetal, and British Patent No. 1,3.
Means for enzymatically decomposing gelatin in a light-sensitive silver halide emulsion as described in US Pat. No. 54,186, or photosensitive halide as described in US Pat. No. 4,076,539. By preparing silver particles in the presence of a surfactant, various means such as a means for omitting the use of a protective polymer can be applied.

The photosensitive silver halide preferably has a small grain size in order to suppress white turbidity after image formation and to obtain good image quality. The average particle size is 0.
1 μm or less, preferably 0.01 to 0.1 μm, particularly preferably 0.02 to 0.08 μm. 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-shaped, 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 silver halide is 50% by mass or less, preferably 25 to 0.1% by mass, more preferably 15 to 0.1% by mass, based on the total amount of the silver halide and the organic silver salt described below. It is. Various conditions such as a reaction temperature, a reaction time, and a reaction pressure in the step of converting a part of the organic silver salt into silver halide using the above-mentioned silver halide forming component can be appropriately set according to the purpose of production. , Usually the reaction temperature is-
It is preferable that the reaction time is 23 ° C. to 74 ° C., the reaction time is 0.1 second to 72 hours, and the reaction pressure is set to the atmospheric pressure.

The photosensitive silver halide prepared by the above-mentioned various methods includes, for example, sulfur-containing compounds, gold compounds,
Platinum compounds, palladium compounds, silver compounds, tin compounds,
Chemical sensitization can be performed by a chromium compound or a combination thereof. The method and procedure of the chemical sensitization are described in, for example, U.S. Pat. No. 4,036,650, British Patent No. 1,518,850, and the like.
No. 22430, No. 51-78319, No. 51-811
No. 24 and the like.

The silver halide used in the present invention can be sensitized with a spectral sensitizing dye if necessary. For example, JP-A-63-159814, JP-A-60-140335, JP-A-6-140335
Nos. 3-231437, 63-259651 and 63
-304242, 63-15245, etc.,
U.S. Pat. Nos. 4,639,414 and 4,740,4
No. 55, No. 4,741,966, No. 4,751,
Sensitizing dyes described in each specification such as 175 and 4,835,096 can be used. Useful sensitizing dyes for use in the present invention include, for example, Research D
issue Item 17643 IV-A (1
December 978, p. 23), and the document described or cited in Item 1831X (p. 437, August 1978). 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.

(Binder) As the polymer binder used in the photosensitive layer or the non-photosensitive layer of the heat-developable material of the present invention, polyvinyl butyral, polyacrylamide, polystyrene,
Examples include polyvinyl acetate, polyurethane, polyacrylate, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, vinyl chloride-vinyl acetate copolymer, and styrene-butadiene-acryl copolymer. After further drying, after forming a film, those having a low equilibrium water content of the coating film are preferred, and particularly those having a low water content include, for example, organic solvent-based cellulose acetate, cellulose acetate butyrate and polyacetal. it can. Polyacetal refers to a polymer obtained by producing polyvinyl alcohol by saponifying polyvinyl acetate and reacting the polyvinyl alcohol with an aldehyde compound.A preferred polyacetal in the present invention is a polyacetal that has been acetalized with butyraldehyde. Preferred are polyacetals obtained by acetalization with butyral and acetaldehyde (polyacetals in a narrow sense). 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.

(Crosslinking agent) The binder alone can maintain the adhesion to the lower layer and the upper layer and obtain a film strength which is hard to be damaged by forming a film alone. Film 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 have at least two isocyanate groups.
Crosslinking agents having at least two carbodiimide groups, alkoxysilane crosslinking agents having at least two alkoxy groups, and vinylsulfonyl crosslinking agents having at least two vinylsulfonyl groups. Preferred crosslinking agents are shown below.

H1: hexamethylene diisocyanate H2: trimer of hexamethylene diisocyanate H3: tolylene diisocyanate H4: phenylene diisocyanate H5: xylylene diisocyanate H6: 1,3-bis (isocyanate methyl) ) Cyclohexane H7: tetramethylene xylylene diisocyanate H8: m-isopropenyl α, α-dimethylbenzyl isocyanate H9: phenylaminopropyltrimethoxysilane H10: p-methylphenylpropyltrimethoxysilane H11: dimethylaminopropyltrimethoxysilane H12 : Diethoxyaminopropyltriethoxysilane H13: 1,3-bis (vinylsulfonamido) propane H14: 1,2-bis (vinylsulfonamido) ethane H1 : 1,3-bis (vinyl sulfonamido) -2-
Hydroxypropane H16: bis (vinylsulfonamide) ether carbodiimide crosslinking agents (H17 to H21) are shown below.

[0032]

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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.

(Dye optionally used in AI layer or BC layer) The heat developing material of the present invention is provided with an AI layer or a BC layer for preventing irradiation or halation of the heat developing material, if necessary. The dye used in the AI layer or the BC layer may be any dye that absorbs image exposure light, and a preferred example is described in JP-A-2-216140.
And dyes described in JP-A Nos. 7-13295 and 7-11432 and U.S. Pat. No. 5,380,380,635.

(Matting agent) The matting agent may be either an organic substance or an inorganic substance. Examples of the inorganic matting agent include silica described in Swiss Patent No. 330,158 and Swiss Patent No. 330,158. Polystyrene or polymethacrylate according to US Pat.
For example, polyacrylonitrile described in Japanese Patent No. 079,257 and polycarbonate described in US Patent No. 3,022,169 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. In the present invention, the particle diameter of the matting agent indicates the diameter converted into a sphere.
The matting agent used in the present invention has an average particle size of 0.5 to 1
0 μm, more preferably 1.0 to
It is 8.0 μm. The matting agent has a monodispersity of 50 or less, more preferably 40 or less, and particularly preferably 20 or less. here,
The monodispersity of the particles is represented by a number obtained by dividing the standard deviation of the particle size by the average value of the particle size and multiplying by 100. The method for adding the matting agent according to the present invention may be a method in which the matting agent is dispersed in a coating liquid in advance, or a method in which the coating liquid is applied and then the matting agent is sprayed before drying is completed. You may.

(Support) The support is preferably a support such as polyethylene terephthalate, polyethylene naphthalate or syndiotactic polystyrene.
A film having a thickness of 50 μm to 400 μm, which is axially stretched and heat-fixed, has high optical isotropy, and has good dimensional stability.

(Image Exposure) As an exposure method, see
JP-A-304869, JP-A-9-311403 and JP-A-2
000-10230, and the like.

(Heat Developing Apparatus) Examples of the apparatus for developing a heat developing material include those described in JP-A Nos. 11-65067, 11-72897, and 11-84619.

[0040]

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.

<< Undercoat Coating Solution 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 (30% solids) is diluted 15-fold.

<< Undercoat Coating Solution b-1 >> A copolymer latex liquid (solid content: 30%) of butyl acrylate (40% by weight) styrene (20% by weight) glycidyl acrylate (40% by weight) is diluted 15 times. .

Subsequently, the undercoat layer A-1 and the undercoat layer B-1
A 12 W / m ² · min corona discharge is applied to the upper surface of the undercoating layer A-1. On the undercoat layer B-1, and a lower undercoat layer B-2 (for BC layer) having an antistatic function by coating and drying the following undercoat upper layer coating solution b-2. .

<< Lower Coating Upper Layer Coating Solution a-2 >> 1: 2 copolymer of styrene and butadiene 0.4 g / m ² silica particles (average particle size 3 μm) 0.05 g / m ² AQH: described in Table 1 1 × 10 ^-5 mol / m ² << Undercoat upper layer coating solution b-2 >> 1: 2 copolymer of styrene and butadiene 0.4 g / m ² Conductive tin oxide fine particles (average particle diameter 16 nm) 0.023 g / m ² .

<Preparation of silver halide grain emulsion A>
After dissolving 7.5 g of inert gelatin and 10 mg of potassium bromide in 0 ml 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) molar ratio of potassium bromide and potassium iodide is 0.43
370 ml of an aqueous solution containing 6 mol was added over 10 minutes by a controlled double jet method while maintaining 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, 4-hydroxy-6-methyl-1,3,3
a, 7-Tetrazaindene was added to 0.3 g, and the pH was adjusted to 5 with NaOH to obtain a cubic iodobromide having an average grain size of 0.036 μm, a variation coefficient of the projected diameter area of 8%, and a [100] face ratio of 87%. Silver particles were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant and desalting treatment.
l.

<Preparation of Water-Dispersed Organic Silver Salt> 111.4 g of behenic acid and 83.8 of arachidic acid were added to 3980 ml of pure water.
g and 54.9 g of stearic acid were dissolved at 80 ° C. Next, while stirring at a high speed, 540.2 ml of a 1.5 mol aqueous sodium hydroxide solution was added, 6.9 ml of concentrated nitric acid was added, and 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 420 ml of pure water were 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, it was centrifugally dehydrated and dried.

<Coating of Photosensitive Layer and BC Layer> The following layers on the photosensitive layer side and on the BC side were coated on the support provided with the undercoat layer. The drying was performed on both the photosensitive layer side and the BC side by 4 times each.
Performed at 5 ° C. for 1 minute.

<< Coating on BC Layer Side >> On the back surface side, a coating solution prepared from the following composition was simultaneously coated and dried so as to have the following coating amount to form a BC layer.

<< Application of BC Layer >> Binder: PVB-1 (described later) 1.8 g / m ² Dye: C1 2.1 × 10 ⁻⁵ mol / m ² << Application of BC Protective Layer >> Cellulose Acetate Butyrate 1 g / m ² matting agent (PMMA: average particle size 5 μm) 0.12 g / m ² <Coating on photosensitive layer side><< Application of AI layer >> Binder: described in Table 1 0.4 g / m ² Dye: C1 A coating solution of the following composition was prepared for forming a 2 × 10 ⁻⁵ mol / m ² photosensitive layer, and the coating solution was coated and dried so that the following amount was obtained. 1.3 as silver
An amount of the organic silver salt preparation of 6 g / m ² was mixed with the polymer binder.

[0051] Binder: Table 1 2.6 g / m ² 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: K1 3.3 mmol / m ² << Surface protective layer >> A coating solution prepared by adding the following composition was coated on the photosensitive layer so as to have the following amount. Coating and drying were performed to form a surface protective layer.

Cellulose acetate butyrate 1.2 g / m ² Phthalazine 0.2 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 particle size 5 μm) 0.5 g / m ² AQH: described in Table 1 1.0 × 10 ⁻⁴ equivalents / m ^{2 The} binder is 2 of a copolymer of polyacetal and styrene and butadiene. Seeds were used. In the former case, methyl ethyl ketone (MEK) was used as the organic solvent, and the styrene-butadiene polymer was formed by aqueous coating in which additives were dispersed in fine particles. As the polyacetal, polyvinyl acetate having a polymerization degree of 500 was saponified by 98%, and then 86% of the remaining hydroxyl groups were butyralized (abbreviated as PVB-1). PVB-1 is B
It was also used as a binder for layer C. In the copolymer of styrene and butadiene, styrene and butadiene were emulsion-copolymerized by a conventional method with a mass composition ratio of 1: 2 (abbreviated as SB-1).

[0053]

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<Evaluation of photographic performance>
After storing at 5 ° C under an atmosphere of 48% relative humidity for 3 days,
Exposure with a 810 nm semiconductor laser exposure sensitometer,
After heating at 120 ° C. for 8 seconds after the exposure, the obtained sample was immediately used as a sample to determine fog and sensitivity. Further, a part of the developed sample was stored in a high-temperature atmosphere of 60 ° C. and 20% RH for 3 days as a heat resistance test, and then an increase in fog was measured. In addition, a part of the developed sample was used as a light resistance test,
The sample was placed on a 0-lux sharksten for 10 hours, and the decrease in the maximum concentration (ΔDmax) of the placed sample was measured. The sensitivity was evaluated by the reciprocal of the ratio of the exposure amount giving a density higher than the fog density by 0.3, and was expressed by relative evaluation using the sample 101 as a reference (100). The heat resistance is better as the increase in fog of the heat test sample is smaller than that of the sample immediately, and the light resistance is better as the decrease in the maximum density is smaller.

(Recyclability of Support) Separation of the support and the coated material on the support from the used thermal developing material is 30 cm.
0.3cm × 0.3cm sample piece of × 30cm size
Cut into small pieces and put into a 1 liter glass beaker.
20 ml of 5% sodium hydroxide and 1 ml of hypochlorous acid
After the addition, the mixture was boiled at 100 ° C. for 60 minutes to observe the peeling of the coated material on the support. The case where a transparent support was obtained was evaluated as “suitable”, and the case where it was not obtained was evaluated as “unsuitable”.

[0056]

[Table 1]

[0057]

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As can be seen from Table 1, when the AQH of the present invention and the crosslinking agent of the present invention are used, the dye is fixed, the fog at the time of heat development is reduced, and photographic characteristics with high sensitivity are obtained, and sharpness, weather resistance and heat resistance are improved. It turns out that it is excellent. Further, since the support does not contain a dye, there is an advantage that the used heat-developable material can be used to separate the coated material from the support and reuse the support.

[0059]

According to the present invention, a heat-developable material having high sensitivity, low fog, and high sharpness can be imparted to the support used for the heat-developable material by imparting production suitability and recyclability, without deteriorating photographic performance. Thus, it was possible to provide a medical heat-developable material free from stains on an intensifying screen even after many X-ray photographing processes.

Claims (5)

[Claims] 1. A heat-sensitive layer comprising 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 and containing a binder, on a support having an undercoat layer. A heat-developable material, wherein an anthraquinone dye having a carboxyl group or a hydroxyl group is fixed to a binder with a crosslinking agent in an undercoat layer or in a layer between the undercoat layer and the photosensitive layer. 2. The heat developing material according to claim 1, wherein the crosslinking agent is a crosslinking agent having an isocyanate group, an alkoxysilane group or a carbodiimide group. 3. The cross-linking agent according to claim 2, wherein the photosensitive layer of the heat-developable material or a layer adjacent to the photosensitive layer has a binder made of polyacetal or a water-dispersible hydrophobic polymer. The heat-developable material according to claim 1, wherein the heat-developable material is used. 4. The heat according to claim 1, wherein the binder used in the undercoat layer or the photosensitive layer of the heat developing material is a polymer having a carboxyl group or a hydroxyl group. Development material. 5. The dye immobilized on the binder has an absorption maximum in the range of 580 nm to 680 nm, and the concentration at the absorption maximum is 0.05 to 0.5. 5. The heat-developable material according to any one of 4.