JPH08220663A - Silver halide photographic sensitive material and method for forming x-ray picture - Google Patents

Abstract

PURPOSE: To provide a silver halide photographic sensitive material having high sensitivity and high picture quality and excellent in scrach resistance and superrapid processability and to furnish a method for forming an X-ray picture. CONSTITUTION: This silver halide photographic sensitive material has >=2 photosensitive silver halide emulsion layers respectively on both sides of a transparent substrate. The emulsion layer closest to the substrate contains a soild dispersed dye having the maximum absorption wavelength between 520-560nm, the average diameter of the silver halide grains contained in the emulsion layer is controlled to <=80% of the average diameter of the silver halide grains contained in the emulsion layer other than the emulsion layer on the same side. An X-ray picture is formed by using such a silver halide photographic sensitive material.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a silver halide photographic light-sensitive material having a photosensitive silver halide emulsion layer on a support and an X-ray image forming method.
The present invention also relates to a silver halide photographic light-sensitive material having excellent scratch resistance and excellent ultra-rapid processability, and an X-ray image forming method.

[0002]

2. Description of the Related Art In medical X-ray silver halide photographic light-sensitive materials, images are sharp and have excellent graininess in order to avoid early detection and misdiagnosis of lesions by photographing various parts of a living body. Is required.

Since the sharpness and graininess of the light-sensitive material affect the visibility of an image and the amount of information thereof, it is extremely important for enhancing the diagnostic ability.

However, in a direct medical X-ray photographic light-sensitive material coated with emulsion on both sides, light emitted from one fluorescent intensifying screen passes through the adjacent silver halide emulsion layer and the light is emitted. Is spread by the support and causes a crossover exposure phenomenon in which the silver halide emulsion layer on the opposite side is imagewise exposed, which is a major factor that deteriorates the sharpness of the image.

Reduces crossover exposure from both sides,
Many proposals have been made to improve the sharpness, for example, JP-A-61-132945, U.S. Pat. No. 4,130,428, and British Patent No. 821352 in which a dye is used in a silver halide emulsion layer or a constituent layer. Etc. However, in these methods, the presence of the dye in the emulsion layer causes the photographic sensitivity to decrease due to the reason that the dye moves to an adjacent layer during coating or storage.

In US Pat. No. 4,803,150, a finely dispersed solid dye is applied as a crossover cut layer below the emulsion layer to substantially eliminate crossover exposure and significantly improve sharpness. The technology is disclosed.
However, because a new crossover cut layer is provided,
Since the amount of binder increases and the drying property deteriorates, there is a drawback that it is not suitable for rapid processing. JP-A-2-266346,
In order to improve this drawback, there is disclosed a technique in which two or more emulsion layers are included and one or more of the emulsion layers contains a solid dispersed dye. However, by simply using this technique, As described above, the influence of the dye on the emulsion causes a decrease in photographic sensitivity. Furthermore, although this technology can improve the drying property, it is essentially only improving by reducing the amount of binder, and conversely, because the pressure resistance deteriorates due to the increase in transport speed in rapid processing, it is still quick. Not suitable for processing.

Particularly in the field of medical light-sensitive materials, rapid processing is strongly desired because the number of X-ray images is increased due to the rapid increase in the number of diagnoses and the number of inspection items, and it is necessary to notify the patient of the diagnosis result as soon as possible. Especially, there are strong demands for angiography and intraoperative imaging.

Further, a medical radiation image is usually formed by combining a fluorescent intensifying screen and a photographic light-sensitive material for X-rays, and the image is given to the radiation image on the fluorescent intensifying screen in addition to the image quality of the light-sensitive material itself. The impact is also very large.

When performing X-ray photography, the combination of the fluorescent intensifying screen and the silver halide photographic light-sensitive material to be used is not particularly specified, but when high-sensitivity photography is required, for example, in the lumbar spine. In photographing, head angiography, magnifying, etc., it is usual to use a high-intensity fluorescent intensifying screen in combination with a standard or high-sensitivity silver halide photographic light-sensitive material. When the image quality is particularly important, for example, in simple imaging of the chest, imaging of the stomach, imaging of bones, a combination of a high-sensitivity fluorescent intensifying screen and a standard-sensitivity silver halide photographic light-sensitive material is used. It is normal. Therefore, the combination of the high-sensitivity fluorescent intensifying screen and the light-sensitive material reduces the sharpness of the image, while the low-sensitivity combination of the fluorescent intensifying screen and the light-sensitive material results in low sensitivity.

Japanese Unexamined Patent Publication (Kokai) No. 3-21898 discloses a method for improving sharpness and graininess by increasing the packing density of phosphors in a fluorescent intensifying screen. Regarding X-ray light-sensitive materials, by combining X-ray light-sensitive materials having silver halide emulsion layers with different photographic characteristics on the front and back and fluorescent intensifying screens with different front and back, crossover light is cut and sharpness is improved. And the tolerance for exposure variations are improved.
No. 266344 is disclosed. This technique aims to obtain various image contrasts by changing the combination with the fluorescent intensifying screen, but in practice, the graininess deteriorates and the diagnosability deteriorates.

Conventionally, image graininess, sharpness, and contrast have been mentioned as factors that greatly affect the image quality of medical X-ray images. Regarding the graininess, for example, by combining the standard photosensitive material SR-G and the standard fluorescent intensifying screen SRO-250 (both made by Konica), X-ray generation that is a normal chest imaging condition Tube tube voltage 11
In the region of 0 KVp or more, 50% or more of the deterioration of graininess is based on the X-ray quantum mottle, and this quantum mottle is X
This greatly deteriorates the graininess and image quality of line photographs. Further, in the case of a combination using a high-sensitivity X-ray film, the quantum mottle is further increased and the image quality is deteriorated.

In order to improve the image quality of X-ray photography, it is necessary to reduce and improve the sharpness while reducing the quantum mottle. This is because when the crossover light of the X-ray photosensitive material itself is cut to improve the sharpness, the image quality is not necessarily improved due to the deterioration of the graininess corresponding to the sharpness improvement. Therefore, as disclosed in JP-A-3-21898 as described above, a method of increasing sharpness and graininess by increasing the packing density of the phosphor of the radiation fluorescent intensifying screen has been carried out.

In the case where a photosensitive material having a phosphor filling rate of 66% or less and a fluorescent intensifying screen and a large amount of crossover light cut is used, the graininess of the sharpness improving portion deteriorates. . Therefore, the crossover light of the X-ray photosensitive material itself is designed to exceed 20% to balance the image quality of graininess and sharpness. However, the image quality of the obtained X-ray photographic image is not sufficient, and further improvement has been desired.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a silver halide photograph having high sensitivity, high image quality, excellent scratch resistance, and ultra-rapid processing property. It is to provide a light-sensitive material and an X-ray image forming method.

[0015]

The above object of the present invention is solved by the following constitution.

1) In a silver halide photographic light-sensitive material having two or more light-sensitive silver halide emulsion layers on both sides of a transparent support, the silver halide emulsion layer closest to the support has a thickness of 520 to 560 nm. Containing a dye in the solid dispersion state having a maximum absorption wavelength between them, and the average grain size of silver halide grains contained in the silver halide emulsion layer is the same as that of the silver halide emulsion layer on the same side. A silver halide photographic light-sensitive material characterized in that the average grain size of silver halide grains contained in a silver emulsion layer is 80% or less.

2) In the above-mentioned silver halide photographic light-sensitive material, the silver coverage of the silver halide emulsion layer closest to the support is the same as the silver coverage of silver halide emulsion layers other than the silver halide emulsion layer on the same side. 50% or less of the silver halide photographic light-sensitive material described in 1 above.

3) In the above silver halide photographic light-sensitive material, 50% or more of the total projected area of silver halide grains contained in the emulsion layer farthest from the support has an aspect ratio of 3 or more. 3. The silver halide photographic light-sensitive material as described in 1 or 2 above.

4) X-ray energy shows an absorption amount of 45% or more with respect to X-rays of 80 KVp, and the filling rate of the phosphor is 68%.
Imagewise exposure is performed by irradiating X-rays with the silver halide photographic light-sensitive material according to claim 1, 2 or 3 on a fluorescent intensifying screen having a phosphor thickness of 135 μm or more and 200 μm or less. An X-ray image forming method characterized in that the method is performed.

5) In the X-ray image forming method as described in 4 above, the sensitivity of the silver halide photographic light-sensitive material has the same wavelength as the main emission peak wavelength of the fluorescent intensifying screen, and the half width is 15 ±. The amount of exposure required for the density of the exposed surface to be a minimum density of ± 0.5 when exposed to a monochromatic light of 5 nm and developed with a developer having the following composition at a developer temperature of 35 ° C and a development time of 25 seconds
An X-ray image forming method having a sensitivity of 0.027 lux seconds to 0.040 lux seconds.

Developer composition potassium hydroxide 21 g potassium sulfite 63 g boric acid 10 g hydroquinone 26 g triethylene glycol 16 g 5-methylbenzotriazole 0.06 g 1-phenyl-3-mercaptotetrazole 0.01 g glacial acetic acid 12 g 1-phenyl-3-pyrazolidone 1.2 g Glutaraldehyde 5g Potassium bromide 4g Add water to make 1 liter and adjust the pH to 10.0.

6) The silver halide photographic light-sensitive material described in 1, 2 or 3 above is processed by an automatic processor for a total processing time of 40 seconds or less, and X described in 4 or 5 above.
Line image forming method.

Silver halide grains are generally prepared and used in the form of silver halide emulsions containing the grains.

The emulsion used in the silver halide photographic light-sensitive material of the present invention may be any silver halide such as silver iodobromide, silver iodochloride and silver iodochlorobromide. The silver halide grains in the photographic emulsion are all isotropically grown such as cubes, octahedrons, and tetrahedrons, or are polyhedral crystals such as spheres, and twins having plane defects. The silver halide grains contained in the emulsion layer farthest from the support have 50% or more of the total projected area and an aspect ratio of 3 or more. It is preferable.

Particularly preferably, tabular grains having an aspect ratio of 3 or more and 5 or less account for 80% or more of the total projected area.

The aspect ratio as used herein means, in a twin grain having two or more parallel twin planes, when the grain is projected from a direction perpendicular to the twin plane, the projected image of the grain has the same area. It is a ratio (ratio of particle diameter / particle thickness) of a diameter when converted into a circular image and a distance (particle thickness) between two particle surfaces parallel to a twin plane.

The particle size can be obtained, for example, by magnifying the particles with an electron microscope at a magnification of 10,000 to 50,000 times and measuring the diameter of the particles on the print or the area at the time of projection.
(The number of particles measured shall be 1000 or more indiscriminately.)
Similarly, the particle thickness can be obtained by actually measuring an electron micrograph.

The silver halide photographic emulsion which can be used in the present invention can be produced by a known method. Although any method such as an acidic method, a neutral method, or an ammonia method may be used, it is preferable to use a double jet method (simultaneous mixing method) as a method of reacting a soluble silver salt with a soluble halogen salt. As one type of the simultaneous mixing method, a method of keeping pAg constant in a liquid phase in which silver halide is produced, that is, a so-called controlled double jet method can be used. According to this method, a silver halide emulsion having a regular crystal form and a substantially uniform grain size can be obtained.

In determining the addition rate, JP-A-54-48
Reference can be made to 521 and 58-49938.

The silver halide emulsion used in the practice of the present invention comprises the Nudel water washing method and flocculation in order to remove soluble salts after the growth of silver halide grains and to obtain a pAg ion concentration suitable for chemical sensitization. A sedimentation method or the like may be used, and a preferable washing method is, for example, Japanese Patent Publication
A method using an aromatic hydrocarbon aldehyde resin containing a sulfo group described in 35-16086 or a desalting method using a polymer flocculant such as Exemplified G-3 and G-8 described in JP-A-2-7037. Can be mentioned.

In the silver halide emulsion according to the present invention, various hydrophilic colloids for wrapping silver halide are used as a binder. For this purpose, gelatin and other synthetic polymers such as polyvinyl alcohol and polyacrylamide, colloidal albumin,
Photographic binders such as polysaccharides, cellulose derivatives and the like may be used.

In the case of chemical sensitization, ordinary sulfur sensitization,
Reduction sensitization, precious metal sensitization and combinations thereof are used. More specific chemical sensitizers include sulfur sensitizers such as allyl thiocarbamide, thiourea, thiosulfate, thioether and cystine; precious metal sensitizers such as potassium chloroaurate, aurath thiosulfate and potassium chloroparadate. Examples thereof include reduction sensitizers such as tin chloride, phenylhydrazine, and retactone.

The photographic emulsions used in the practice of this invention may be spectrally sensitized with cyanine dyes and the like. The sensitizing dyes may be used alone, or a combination thereof may be used, and the combination of the sensitizing dyes is often used particularly for the purpose of supersensitization.

The photographic light-sensitive material using the silver halide photographic emulsion of the present invention is prepared by the steps before and after physical ripening or chemical ripening of the emulsion.
Various photographic additives can be used.

Examples of compounds that can be used in such a process include Research Disclosure (RD) 17643.
And various compounds described in (RD) 18716 and (RD) 308119. The types and locations of the compounds described in these three (RD) are listed below.

Additive RD-17643 RD-18716 RD-308119 Page Classification Page Page Classification Chemical sensitizer 23 III 648 Upper right 996 III Sensitizing dye 23 IV 648-649 996-8 IV A Desensitizing dye 23 IV 998 IV B Dye 25-26 VIII 649-650 1003 VIII Development accelerator 29 XXI 648 Upper right fog inhibitor / stabilizer 24 IV 649 Upper right 1006-7 VI Whitening agent 24 V 998 V Hardener 26 X 651 Left 1004-5 X Interface Activator 26-27 XI 650 Right 1005-6 XI Plasticizer 27 XII 650 Right 1006 XII Sliding Agent 27 XII Matting Agent 28 XVI 650 Right 1008-9 XVI Binder 26 XXII 1003-4 IX Support 28 XVII 1009 XVII Examples of the support used in the silver halide photographic light-sensitive material include those described in the above RD. Suitable supports are plastic films and the like, and the support surface has good adhesiveness of the coating layer. In order to do so, an undercoat layer may be provided, or corona discharge or ultraviolet irradiation may be performed. Then, the emulsion according to the present invention can be coated on both sides of the support thus treated.

The silver halide photographic light-sensitive material of the present invention has two or more light-sensitive silver halide emulsion layers on each side of a transparent support, and the emulsion layer closest to the support has a thickness of 520 to 560 nm. Contains a solid disperse dye having a maximum absorption wavelength.

The solid dispersion referred to in the present invention means that the dye does not exist in the molecular state in the layer of the light-sensitive material and is dispersed and exists as a solid having a size that cannot be substantially diffused in the layer.

In practice, the dye is placed in a ball mill container and ball mill dispersed with the surfactant and beads of zirconium oxide. Thereafter, an aqueous gelatin solution is added to stabilize the solution to obtain a dye solution. As the dispersion method, for example, the method described in JP-A-63-197943 may be used.

The particle size of the solid disperse dye used in the present invention may be 0.3 μm or less, preferably 0.1 μm or less. Alternatively, a needle type may be used. The amount of the dye used in the present invention is not particularly limited, but usually 5 mg to 300 mg per 1 m ² of the light-sensitive material, preferably 50
It is mg to 150 mg.

As the dye, a dye exhibiting absorption having a maximum absorption wavelength between 520 and 560 nm in a solid dispersion state is preferably used. Specifically, they are nonionic (poly) methine dyes including, for example, merocyanine, oxonol, hemioxonol, styryl and arylidene dyes.

Specific compounds include I-1 to 16, II-1 to 3, III-1 to 21, IV-1 to 11 described in JP-A-2-264936 and 1 described in JP-A 1-172828. ~ 2 / O, 1-23 / A can be used.

In the present invention, the average grain size of silver halide grains contained in the emulsion layer closest to the support is the average grain size of silver halide grains contained in the other emulsion layers.
80% or less. It is particularly preferably 30% or more and 70% or less.

More preferably, the amount of silver attached to the emulsion layer closest to the support is 50% or less of the amount of silver attached to the other emulsion layers. Particularly preferably, it is 20% or more and 40% or less.

The silver halide photographic light-sensitive material of the present invention comprises
In addition, if necessary, an antihalation layer, an intermediate layer, a filter layer, etc. can be provided.

In the photographic light-sensitive material of the present invention, the photographic emulsion layer and other hydrophilic colloid layers can be coated on the support or other layers by various coating methods. For coating, a dip coating method, a roller coating method, a curtain coating method, an extrusion coating method, a slide hopper method, or the like can be used. For more information, Research Disclosure, No. 176
Volume, page 27-28, section "Coating procedures" can be used.

The processing of the light-sensitive material of the present invention is carried out, for example, by the above-mentioned R
D-17643 XX to XXI, pages 29 to 30 or 308119 XX to XXI, 1
Treatment with a treatment solution as described on pages 011 to 1012 may be performed.

Developers for black and white photographic processing include dihydroxybenzenes (eg hydroquinone), 3-pyrazolidones (eg 1-phenyl-3-pyrazolidone), aminophenols (eg N-methyl-aminophenol).
Etc. can be used alone or in combination.
It should be noted that the developer may be any known one such as preservative, alkaline agent, pH.
A buffering agent, an antifoggant, a film hardener, a development accelerator, a surfactant, an antifoaming agent, a toning agent, a water softener, a solubilizing agent, a viscosity imparting agent and the like may be used as necessary.

A fixing agent such as thiosulfate or thiocyanate is used in the fixing solution and may further contain a water-soluble aluminum salt such as aluminum sulfate or potassium alum as a hardening agent. In addition, it may contain a preservative, a pH adjuster, a water softener and the like.

In the present invention, the total processing time (Dry to Dry)
It can be processed very quickly in less than 40 seconds. The term "development process time" or "development time" in the present invention means that the leading edge of the photosensitive material to be processed is immersed in the developing tank solution of an automatic developing machine (hereinafter referred to as "developing machine") and then in the next fixing solution. "Fixing time" is the time from immersion in the fixing tank solution to immersion in the next washing tank solution (stabilizing solution).
"Washing time" refers to the time of immersion in the washing tank liquid. "Drying time" is normally 35 ° C to 10
A drying zone in which hot air of 0 ° C., preferably 40 ° C. to 80 ° C. is blown is installed, and it means the time for entering the drying zone. In the developing treatment of the present invention, the developing time is 3 seconds to 15 seconds, preferably 3 seconds to 10 seconds, and the developing temperature is 25 ° C to 50 ° C.
Is preferable, and 30 ° C to 40 ° C is more preferable. The fixing temperature and time are 20 ° C to 50 ° C, preferably 2 seconds to 12 seconds, and 30 ° C to 40 ° C.
2 to 10 seconds is more preferable. Washing or stabilizing bath temperature and time are 0 to 50 ° C, preferably 2 to 15 seconds, 15 ° C to 40 ° C
And more preferably 2 seconds to 8 seconds. According to the method of the present invention,
The developed, fixed and washed (or stabilized) photographic material is dried through a squeeze roller which squeezes the washing water.
The drying is carried out at 40 ° C to 100 ° C, and the drying time can be appropriately changed depending on the ambient temperature, but it is usually 3 seconds to 12 seconds, particularly preferably 40 ° C to 80 ° C for 3 seconds to 8 seconds. Is. It is more preferable to use a far infrared heater.

In the present invention, the developing time is 10 seconds or less, and the replenishing amount of the developing solution is ² per m ^{2 of the} silver halide photographic light-sensitive material.
It can be processed with less than 00 ml.

When the present invention is applied to medical X-ray radiography, for example, a fluorescent intensifying screen containing a phosphor that emits near-ultraviolet light or visible light as a main component upon exposure to penetrating radiation is used. This is exposed by contacting both surfaces of a light-sensitive material prepared by coating the emulsion of the present invention on both surfaces. Here,
The penetrating radiation is a high energy electromagnetic wave and means X-rays and γ-rays.

Preferred phosphors used in the fluorescent intensifying screen according to the present invention include those shown below.

Tungstate phosphor (CaWO ₄ , MgW
O ₄ , CaWO _4, Pb, etc.), terbium-activated rare earth oxysulfide-based phosphor (Y ₂ O ₂ S: Tb, Gd ₂ O ₂ S: Tb, La ₂ O ₂ S: Tb, (Y.Gd) ₂
O ₂ S: Tb, (Y.Gd) O ₂ S: Tb.Tm, etc.], terbium-activated rare earth phosphate-based phosphor (YPO ₄ : Tb, GdPO ₄ : Tb, LaPO ₄ : Tb
Etc.), terbium-activated rare earth oxyhalide-based phosphors (LaOBr: Tb, LaOBr: Tb.Tm, LaOCl: Tb, LaOCl: Tb.
Tm, LaOCl: Tb.Tm.LaOBr: Tb GdOBr: Tb GdOCl: Tb
Etc.), thulium activated rare earth oxyhalide phosphor (LaOBr: Tm, LaOCl: Tm, etc.), barium sulfate phosphor _{[BaSO 4: Pb, BaSO 4:} Eu 2+, (Ba.Sr) SO 4: Eu ²⁺ etc.],
Divalent eurobium-activated alkaline earth metal phosphate-based phosphor [(Ba ₂ PO ₄ ) ₂ : Eu ²⁺ , (Ba ₂ PO ₄ ) ₂ : Eu ^2+, etc.] Divalent eurobium-activated alkaline earth metal Fluorohalide-based phosphor [BaFCl: Eu ²⁺ , BaFBr: Eu ²⁺ , BaFCl: Eu ²⁺ .Tb, Ba
FBr: Eu ²⁺ .Tb, BaF ₂・ BaCl ・ KCl: Eu ²⁺ , (Ba ・ Mg) F ₂・ BaCl ・
KCl: Eu ^2+, etc.], iodide-based phosphors (CsI: Na, CsI: Tl,
NaI, KI: Tl, etc.), sulfide-based phosphor [ZnS: Ag (Zn.Cd) S:
Ag, (Zn.Cd) S: Cu, (Zn.Cd) S: Cu.Al, etc.], hafnium phosphate-based phosphors (HfP ₂ O ₇ : Cu, etc.), provided that the phosphor used in the present invention is The phosphor is not limited, and any phosphor that emits light in the visible or near-ultraviolet region upon irradiation with radiation can be used.

The fluorescent intensifying screen of the present invention is preferably filled with a phosphor in a gradient particle size structure. In particular, it is preferable to apply large-diameter phosphor particles to the surface protective layer side, and to apply small-diameter phosphor particles to the support side.
The size of 2.0 μm and the large particle size is preferably in the range of 10 to 30 μm.

The fluorescent intensifying screen is manufactured by a step of forming a phosphor sheet composed of a binder and a phosphor, placing the phosphor sheet on a support, and heating the binder sheet at a temperature not lower than the softening temperature or melting point of the binder. It is preferable to manufacture the phosphor sheet in a step of adhering the phosphor sheet to a support while compressing.

For the phosphor sheet which becomes the phosphor layer of the fluorescent intensifying screen, the coating solution in which the phosphor is uniformly dispersed in the binder solution is applied onto a temporary support for forming the phosphor sheet and dried. After that, it can be manufactured by peeling from the temporary support. That is, first, a binder and phosphor particles are added to an appropriate organic solvent and mixed by stirring to prepare a coating liquid in which the phosphor is uniformly dispersed in the binder.

The binder has a softening temperature or melting point of 30.
A thermoplastic elastomer of ℃ to 150 ℃ is used alone or in combination with other binders. Since the thermoplastic elastomer has elasticity at normal temperature and becomes fluid when heated, it is possible to prevent the phosphor from being damaged by the pressure during compression. Examples of thermoplastic elastomers are the group consisting of polystyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, ethylene vinyl acetate, polyvinyl chloride, natural rubber, fluororubber, polyisoprene, chlorinated polyethylene, styrene-butadiene rubber and silicone rubber. At least one thermoplastic elastomer selected from the above is included. The mixing ratio of the thermoplastic resin in the binder may be 10% by weight or more and 100% by weight or less, but the binder should be composed of as many thermoplastic elastomers as possible, particularly 100% by weight of the thermoplastic elastomer. preferable.

Examples of the solvent for preparing the coating solution include lower alcohols such as methanol, ethanol, n-propanol and n-butanol, chlorine atom-containing hydrocarbons such as methylene chloride and ethylene chloride, acetone, methyl ethyl ketone and methyl isobutyl ketone. Ketones, such as
Mention may be made of esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate and butyl acetate, ethers such as dioxane, ethylene glycol monoethyl ester, ethylene glycol monomethyl ester and mixtures thereof.

The mixing ratio of the binder and the phosphor in the coating solution varies depending on the characteristics of the target fluorescent intensifying screen, the kind of the phosphor, etc., but generally the mixing ratio of the binder and the phosphor is 1 :.
It is selected from the range of 1 to 1: 100 (weight ratio), especially 1:
It is preferable to select from the range of 8 to 1:40 (weight ratio).

In the coating liquid, a dispersant for improving the dispersibility of the phosphor in the coating liquid, or for improving the binding force between the binder and the phosphor in the formed phosphor layer. Various additives such as plasticizers may be mixed.

Examples of dispersants include phthalic acid, stearic acid, caproic acid, lipophilic surfactants and the like.

Examples of the plasticizer include triphenyl phosphate, tricresyl phosphate, diphenyl phosphate, and other phosphate esters, diethyl phthalate, dimethoxyethyl phthalate, and other phthalate esters, ethyl phthalyl glycolate, and butyl phthalbutyl glycolate. Examples thereof include glycolic acid esters, polyesters of triethylene glycol and adipic acid, polyesters of polyethylene glycol and aliphatic dibasic acids such as polyesters of diethylene glycol and succinic acid, and the like.

The coating solution containing the phosphor and the binder prepared as described above is uniformly applied to the surface of the temporary support for sheet formation to form a coating film of the coating solution.

As the coating means, for example, a doctor blade, a roll coater, a knife coater or the like can be used.

As the temporary support, for example, those made of various materials such as glass, wool, cotton, paper and metal can be used, but a sheet or roll which is flexible in handling as an information recording material. Those that can be processed into are preferred. From this point, for example, cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, plastic film such as polycarbonate film, aluminum foil, metal sheet such as aluminum alloy foil, general paper and, for example, for photography Base paper, coated paper or base paper for printing such as art paper, baryta paper, resin coated paper, Belgian patent 78
Particularly preferred are processed papers such as papers sized with polysaccharides as described in 4,615, pigment papers containing pigments such as titanium dioxide, papers sized with polyvinyl alcohol and the like.

A coating solution for forming a phosphor layer is applied onto a temporary support, dried, and then peeled from the temporary support to obtain a phosphor sheet which becomes a phosphor layer of a fluorescent intensifying screen. Therefore, it is preferable that the surface of the temporary support is coated with a release agent in advance so that the formed phosphor sheet can be easily separated from the temporary support.

The operation will be described. A sheet for setting the phosphor formed as described above is prepared. This support can be arbitrarily selected from the materials listed for the temporary support.

Known fluorescent intensifying screens may be provided with a subbing layer for imparting adhesiveness by coating a polymer material such as gelatin on the surface of the support in order to strengthen the bond between the support and the phosphor layer,
In order to improve sensitivity and image quality (sharpness, graininess), a light reflecting layer made of a light reflecting substance such as titanium dioxide or a light absorbing layer made of a light absorbing substance such as carbon black may be provided.

The support used in the present invention can also be provided with these various layers, and the structure thereof can be arbitrarily selected according to the desired purpose and application of the fluorescent intensifying screen.

The phosphor sheet obtained by the above is placed on a support, and the phosphor sheet and the phosphor sheet are adhered to the support while being compressed at the softening temperature or the melting point or higher of the binder.

In this way, the sheet can be spread thinly by using the method of crimping without being fixed on the phosphor sheet support in advance, not only preventing the phosphor from being damaged but also fixing the sheet. A higher phosphor filling rate can be obtained with the same pressure as compared with the case of applying the pressure.

Examples of the compression apparatus used for the compression treatment of the present invention include commonly known ones such as a calender roll and a hot press. For example, the compression treatment with a calender roll is performed by placing the phosphor sheet obtained by on a support and passing it at a constant speed between rollers heated to the softening temperature or the melting point or higher of the binder. However, the compression device used in the present invention is not limited to these, and any device can be used as long as it can compress the sheet while heating it. The pressure during compression is 50
It is preferably at least kg / cm ² .

Usually, in the fluorescent intensifying screen, a transparent protective film for physically and chemically protecting the phosphor layer is provided on the surface of the phosphor layer on the side opposite to the side in contact with the support. . It is preferable to install such a transparent protective film also in the fluorescent intensifying screen of the present invention. The thickness of the protective film is generally
It is in the range of 0.1 to 20 μm.

The transparent protective layer is, for example, a cellulose derivative such as cellulose acetate or nitrocellulose, or a synthetic polymer material such as polymethyl methacrylate, polyethylene terephthalate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer. Can be formed by a method in which a solution prepared by dissolving is prepared in a suitable solvent is applied to the surface of the phosphor layer.

Alternatively, a plastic sheet made of polyethylene terephthalate, polyethylene naphthalate, polyethylene, polyvinylidene chloride, polyamide, or the like,
Alternatively, a protective film forming sheet such as a transparent glass plate may be separately prepared and adhered to the surface of the phosphor layer by using an appropriate adhesive.

The protective layer used in the fluorescent intensifying screen of the present invention is preferably a film formed of a coating film containing a fluorine-based resin soluble in an organic solvent. Fluorine-based resin is a polymer of olefin containing fluorine (fluoroolefin),
Alternatively, it refers to a copolymer containing an olefin containing fluorine as a copolymer component. The film formed of the coating film of the fluororesin may be crosslinked. Fluorine-based protective film has the advantage that stains such as plasticizers that come out of the film when it comes into contact with other materials or X-ray film do not easily soak into the protective film, so the stains can be easily removed by wiping. There is.

As a material for forming a protective film, when an organic solvent-soluble fluorine resin is used, this resin was dissolved in an appropriate solvent for preparation. That is, the protective film is formed by uniformly applying a protective film-forming material coating liquid containing an organic solvent-soluble fluorine-based resin on the surface of the phosphor layer using a doctor blade or the like, and drying the coating. The formation of this protective film may be performed simultaneously with the formation of the phosphor by simultaneous multilayer coating.

The fluorine-based resin is a polymer of a fluorine-containing olefin (fluoroolefin) or a copolymer containing a fluorine-containing olefin as a copolymer component, such as polytetrafluoroethylene, polychlorotrifluoroethylene, poly Mention may be made, for example, of ethylene fluoride, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer and fluoroolein-vinyl ether copolymer oven.

Fluorine-based resins are generally insoluble in organic solvents, but copolymers containing fluoroolefin as a copolymer component become soluble in organic solvents due to the constitutional units other than the fluoroolefin to be copolymerized. The protective layer can be easily formed by applying a solution prepared by dissolving in a suitable solvent onto the phosphor layer and drying. Examples of such copolymers include fluoroolefin-vinyl ether copolymers. Further, since polytetrafluoroethylene and its modified products are also soluble in a suitable fluorine-based organic solvent such as a perfluoro solvent, they are protected by coating as in the case of the copolymer containing the above fluoroolefin as a copolymer component. A film can be formed.

The protective film may contain a resin other than the fluorine-based resin, and may contain a crosslinking agent, a hardener, an anti-yellowing agent, and the like. However, in order to sufficiently achieve the above-mentioned object, the content of the fluorine-based resin in the protective film is preferably 30% by weight or more, more preferably 50% by weight or more, and most preferably 70% by weight or more. .

Examples of the resin other than the fluorine-based resin contained in the protective film include polyurethane resin, polyacrylic resin, cellulose derivative, polymethylmethacrylate, polyester and epoxy resin.

The protective film of the fluorescent intensifying screen used in the present invention is either a polysiloxane skeleton-containing oligomer or a perfluoroalkyl group-containing oligomer,
Or you may form from the coating film containing both.

The polysiloxane skeleton-containing oligomer has, for example, a dimethylpolysiloxane skeleton,
It preferably has at least one functional group, for example, a hydroxyl group, and preferably has a molecular weight of 500 to 100,000. In particular, the molecular weight is preferably in the range of 1000 to 10000, and more preferably 3000 to 10000.
Range. Further, an oligomer containing a perfluoroalkyl group such as a tetrafluoroethylene group is
It is desirable that the molecule contains at least one functional group, for example, a hydroxyl group, and the molecular weight is preferably in the range of 500 to 100,000. In particular, the molecular weight is preferably in the range of 100 to 100,000, more preferably 100 to 100,000.

If an oligomer containing a functional group is used, a cross-linking reaction occurs between the oligomer and the protective layer film forming resin at the time of forming the protective film, and the oligomer is incorporated into the molecular structure of the film forming resin. The oligomer is not removed from the protective film even by repeated use of the fluorescent intensifying screen for a long period of time, or the surface of the protective film is cleaned, and the addition effect of the oligomer is effective for a long time. The use of The oligomer is preferably contained in the protective film in an amount of 0.01 to 10% by weight, particularly preferably 0.1 to 2% by weight.

The protective layer may contain perfluoroolefin resin powder or silicone resin powder. As the perfluoroolefin resin powder or silicon resin powder, those having an average particle size of 0.1 to 10 μm are preferable, and particularly preferably 0.3 to 5 μm. These perfluoroolefin resin powders or silicone resin powders are contained in the protective film in an amount of 0.
It is preferably contained in an amount of 5 to 30% by weight, more preferably 2 to 20% by weight, most preferably 5 to 15% by weight.

The protective film of the fluorescent intensifying screen is preferably a transparent synthetic resin layer having a thickness of 5 μm or less formed by coating on the phosphor layer. By using such a thin protective layer, the distance from the phosphor of the fluorescent intensifying screen paper to the silver halide emulsion is shortened, which contributes to the improvement of the sharpness of the obtained X-ray image.

The filling rate of the phosphor in the present invention can be obtained from the following formula from the porosity of the phosphor layer formed on the support.

[0089]

[Equation 1]

However, V; total volume of phosphor layer Vair; air volume in phosphor A; total weight of phosphor px; density of phosphor py; density of binder pair; air density a; of phosphor Weight b; Weight of binder Further, in the formula (1), since the pair is almost 0, the formula (1) can be approximately represented by the following formula (2).

[0091]

[Equation 2]

However, the definitions of V, Vair, px, py, a and b are the same as in the equation (1). In the present invention, the porosity of the phosphor layer is calculated by the equation (2). The filling rate of the phosphor can be calculated by the following equation (3).

[0093]

(Equation 3)

However, the definitions of V, Vair, px, py, a and b are the same as in the equation (1).

The fluorescent intensifying screen of the present invention is 40% or more with respect to the X-ray energy of 80 kVp in the X-ray generator having an intrinsic filtration of 2.2 mm of aluminum depending on the filling rate and thickness of the phosphor. It is preferable to use a combination of the fluorescent intensifying screen A showing the absorption amount of 1) and the fluorescent intensifying screen B showing the absorption amount of 50% or more and having a larger absorption amount than the fluorescent intensifying screen A.
The X-ray absorption amount of the fluorescent intensifying screen can be measured by the following method.

X-rays generated from a tungsten target tube operated at 80 kVp with three-phase power supply were transmitted through an aluminum plate having a thickness of 3 mm and fixed at a position 200 cm from the tungsten anode of the target tube. After reaching the fluorescent intensifying screen, the amount of X-rays transmitted through the fluorescent intensifying screen was measured at a position 50 cm after the phosphor layer of the fluorescent intensifying screen using an ionization type dosimeter, and Calculate the absorption amount. As a reference, the X-ray dose measured at the above measurement position without passing through the fluorescent intensifying screen can be used.

The thickness of the phosphor is preferably 120 μm or less,
The fluorescent intensifying screen A is preferably 120 μm or more, and the fluorescent intensifying screen B is preferably 150 μm or more. More preferably, the filling rate of the phosphor at this time is 65% or more.

In a further preferred embodiment of the present invention, the fluorescent intensifying screen B has an absorption amount for X-rays of 80 kVp.
25% or more, and more preferably 30% or more higher than the absorption amount of

The production of the fluorescent intensifying screen of the present invention is described in JP-A-6-75.
It can be prepared according to the method disclosed in No. 097. That is, the phosphor, the binder, the surface protective layer, the material for the conductive layer, and the process for producing them in combination are described in JP-A-6-
It is preferably prepared according to the method disclosed in No. 75097. Further, it is preferable that large particles are arranged near the surface protective layer of the phosphor by a multilayer coating method or the like.

[0100]

Embodiments of the present invention will be described below. Naturally, the invention is not limited to the examples described below.

Example 1 (Preparation of silver iodide fine particles) <Solution A> 100 g ossein gelatin 8.5 g Distilled water to 2000 ml <Solution B> AgNO ₃ 360 g Distilled water 605 ml <Solution C> KI 352 g Solution A was added to a reaction vessel having a volume of 605 ml with distilled water, and solution B and solution C were added at a constant rate over 30 minutes by the simultaneous mixing method while maintaining the temperature at 40 ° C and stirring. The pAg during the addition was kept at 13.5 by a conventional pAg control means. The silver iodide formed is β-AgI and γ-Ag with an average grain size of 0.06 μm.
It was a mixture of I. This emulsion is called a silver iodide fine grain emulsion.

(Preparation of Solid Fine Particle Dispersion of Spectral Sensitizing Dye) The following spectral sensitizing dyes (A) and (B) were added at a ratio of 100: 1 to water preliminarily adjusted to 27 ° C., and a high speed stirrer was used. A solid fine particle dispersion of the spectral sensitizing dye was obtained by stirring with a (dissolver) at 3500 rpm for 30 to 120 minutes. At this time, the concentration of the sensitizing dye (A) was adjusted to 2%.

Sensitizing dye (A): 5,5′-dichloro-9-ethyl-3,
Anhydrous 3'-di (3-sulfopropyl) oxacarbocyanine sensitizing dye (B): 5,5'-di (butoxycarbonyl) -1,1'diethyl-3,3'-di (4-sulfobutyl) ) Benzimidazolocarbocyanine sodium salt anhydrous (Preparation of hexagonal tabular seed emulsion) A hexagonal tabular seed emulsion Em-A having a silver iodide content of 2.0 mol% was prepared by the following method.

[0104] <solution A> ossein gelatin 60.2g Distilled water _{20.0l HO- (CH 2 CH 2 O} ) n- [CH (CH 3) CH 2 O] 17 - (CH 2 CH 2 O) mH (n + m = 5 ~ 7) 10% methanol solution 5.6ml KBr 26.8g 10% H ₂ SO ₄ 144ml <Solution B> AgNO ₃ 1487.5g Make distilled water 3500ml <Solution C> KBr 1029g KI 29.3g Distilled water 3500ml <Solution D> 1.75N KBr aqueous solution Solution A and solution C are added to solution A using the mixing stirrer disclosed in Japanese Patent Publication Nos. 58-58288 and 58-58289 at the following potential control amount of 35 ° C. 64.1 ml of each was added to the double-sided mixing method over a period of 2 minutes to perform nucleation.

After stopping the addition of Solution B and Solution C, 60
The temperature of solution A was raised to 60 ° C. over a period of time, and solution B and solution C were again added by the simultaneous mixing method at a flow rate of 68.5 ml / min for 50 minutes.

During this period, the silver potential (measured with a silver ion selective electrode using a saturated silver-silver chloride electrode as a reference electrode) was controlled to be +6 mV using the solution D. 3% KOH after addition
The pH was adjusted to 6 by means of desalting and washing with water to give a seed emulsion Em-A. Seed emulsion Em-A prepared in this way
90% or more of the total projected area of silver halide grains consists of hexagonal tabular grains with a maximum adjacent side ratio of 1.0 to 2.0, the hexagonal tabular average thickness is 0.07 μm, and the average diameter (converted to a circle diameter) is 0.5 μm. The coefficient was found to be 25% by electron microscope observation.

(Preparation of Tabular Emulsion Em-1) A tabular silver iodobromide emulsion Em-1 containing 1.3 mol% of silver iodide was prepared using the following 5 kinds of solutions.

[0108] <solution A> ossein gelatin _{29.4g HO- (CH 2 CH 2 O} ) n- [CH (CH 3) CH 2 O] 17 - (CH 2 CH 2 O) mH (n + m = 5~ 7) 10% methanol solution 1.25 ml seed emulsion Em-A 1.91 mol equivalent Make up to 3000 ml with distilled water <Solution B> 3.50N AgNO ₃ aqueous solution 1976 ml <Solution C> KBr 823g Make 1976 ml with distilled water <Solution D> Iodide Equivalent to 0.077 mol of silver fine particle emulsion <Solution E> 1.75 KBr aqueous solution Using the mixing stirrer shown in Japanese Patent Publication Nos. 58-58288 and 58-58289 at the following potential control amount of 60 ° C, Solution A and Solution By using the simultaneous mixing method (triple jet method), 110 ml of each of B and solution C and the total amount of solution D were mixed with each other for 40 minutes so that the flow rate at the end of addition was double the flow rate at the start of addition. Additional growth of the coating layer was performed.

Then, the remaining coating liquids of solution B and solution C were continuously processed by the double jet method for 70 minutes so that the flow rate at the end of addition was 1.5 times the flow rate at the start of addition. Was grown.

During this period, the silver potential was controlled to be +20 mV by using the solution D.

After the addition is completed, in order to remove excess salts,
Precipitation desalting was performed by the method described below.

1. The reaction liquid after mixing was brought to 40 ° C., and 20 g / AgX 1 mol of the exemplified coagulating gelatin agent G-3 was added to the mixture to give 56 wt%.
Add acetic acid to reduce the pH to the value shown in Table 1, leave it still, and decant it.

2. Add 1.8 l / AgX 1 mol of pure water at 40 ° C and add 1
After stirring for 0 minutes, leave still and decant.

3. Repeat step 2 above once more.

4. After that, add 15 g / AgX 1 mol of gelatin, sodium carbonate and water to adjust the pH to 6.0 and disperse to 450 cc / AgX1.
Finish to a mole.

Approximately 3000 particles of Em-1 were observed and measured by an electron microscope, and the shape was analyzed.
The tabular grains were 0.73 μm and grain thickness was 0.15 μm, and the coefficient of variation was 24%.

Adjustment of EM-2 (silver iodobromide tabular emulsion) In the adjustment method of EM-1, the average circle equivalent diameter of 0.55 μm and the average thickness were changed by changing the silver ion potential during the adjustment.
A 0.27 μm silver iodobromide emulsion EM-2 was prepared.

(Preparation of monodisperse cubic seed emulsion EM-B) <Solution A> Ocein gelatin 30 g KBr 1.25 g Nitric acid (0.1 N) 150 ml Distilled water to 7700 ml <Solution B> KBr 6 g KI 0.16 g Distilled water <Solution C> KBr 680g KI 20g Distilled water to 2480ml <Solution D> Silver nitrate 8.4g Nitric acid (0.1N) 32ml Distilled water to 740ml <Solution E> Silver nitrate 991.6g Nitric acid (0.1N) 80ml Solution B and solution D were added over 10 minutes by double jet method to solution A which was vigorously stirred at 60 ° C. with distilled water to 2480 ml. Then, the solution C and the solution E were added by the double jet method over 140 minutes. At this time, the initial addition flow rate is 1/8 of the final addition flow rate.
So I sensitized linearly with time. While these solutions were being added, the pH was constantly adjusted to 2 and pAg = 8. After the addition is complete, raise the pH to 6 with sodium carbonate and
Immediately after adding 150 g, desalting and washing with water
A silver iodobromide monodisperse cubic seed emulsion EM-B containing 0.3 μm of silver iodide (2 mol%) was obtained. According to electron microscope observation, the generation rate of twins was 1% or less in number.

(Preparation of Normal Crystal Core / Shell Emulsion EM-3) A normal crystal emulsion EM-3 containing 2.0 mol% AgI was prepared using the following 5 kinds of solutions.

[0120] <solution A> ossein gelatin _{75.5g HO- (CH 2 CH 2 O} ) n- [CH (CH 3) CH 2 O] 17 - (CH 2 CH 2 O) mH (n + m = 5.7) 15% 10% aqueous methanol solution Emulsion EM-B 2.98 mol equivalent Make up to 4000 ml with distilled water <Solution B> AgNO ₃ 46.2 g Add ammonia solution equivalent to AgNO ₃ and distilled water to 259 ml.
<Solution C> AgNO ₃ 647.6g Add ammonia solution equivalent to AgNO ₃ and distilled water to 1088m.
L <Solution D> KBr 22.6g KI 13.5g Distilled water to 259ml <Solution E> KBr 453.3g Distilled water to 1088ml Solution A is kept at 40 ° C in the reaction vessel, and further ammonia water and acetic acid are added. The pH was adjusted to 9.5.

After adjusting the pAg to 7.3 with an ammoniacal silver ion solution, the solution B and the solution D were added by the double jet method while keeping the pH and pAg constant, and silver iodobromide containing 30 mol% of silver iodide was added. The layers were allowed to form.

After adjusting the pH to 9.0 and pAg to 9.0 using acetic acid and KBr, solution C and solution E were added at the same time and grown, and then grown to 90% of the particle size. The pH at this time is 9.0
From 8.20 down gradually.

After adding the KBr solution to adjust the pAg to 11, solution C and solution E were further added to grow while gradually lowering the pH to 8 to obtain a silver iodobromide emulsion containing 2 mol% of silver iodide.

After the addition is completed, in order to remove excess salts,
Precipitation desalination was carried out in the same manner as in EM-1, and an aqueous gelatin solution containing 92.2 g of ossein gelatin was added to 2500 ml,
The mixture was redispersed with stirring to give EM-3.

Approximately 3000 particles of EM-3 were observed and measured by an electron microscope, and the shape was analyzed. The average particle diameter was 0.40.
The particles were monodisperse spherical particles having a size of μm and a distribution of 12%.

Next, the obtained emulsion was spectrally and chemically sensitized by the following methods.

After the emulsion was heated to 50 ° C., the above solid fine particle dispersion was added so that the amount of the sensitizing dye (A) was 460 mg per mol of silver, and then ammonium thiocyanate was added to 7.0 × 10 6 per mol of silver. ^-4 moles, and 6 × 10 ^-6 moles of chloroauric acid and 6 × 10 ^-5 moles of sodium thiosulfate were added for chemical ripening, and 3 × 10 ^-3 moles / Ag of 1 mole of the silver iodide fine grain emulsion was added. , 4-Hydroxy-6-methyl-1,3,3a, 7-tetrazaindene (TAI) stabilized with 3 × 10 ^-2 mol.

(Preparation of Sample) To each of the obtained emulsions, the following various additives were added to prepare emulsion solutions (photosensitive silver halide coating solutions). The amount of addition is shown in an amount per mole of silver halide.

T-Butyl-catechol 400 mg Polyvinylpyrrolidone (molecular weight 10.000) 1.0 g Styrene maleic anhydride copolymer 2.5 g Trimethylolpropane 10 g Diethylene glycol 5 g Nitrophenyl-triphenylphosphonium chloride 50 mg 1,3-Dihydroxybenzene-4-sulfone Ammonium acid 4 g 2-Mercaptobenzindazole-5-sodium sulfonate 1.5 mg nC ₄ H ₉ OCH ₂ CH (OH) CH ₂ N (CH ₂ COOH) ₂ 1g

[0130]

Embedded image

The additives used for the protective layer are as follows. The added amount is shown as an amount per 1 g of gelatin.

Coating liquid for protective layer Area Matting agent composed of polymethylmethacrylate having an average particle size of 7 μm 7 mg Colloidal silica (average particle size 0,013 μm) 70 mg 2,4-dichloro-6-hydroxy-1,3,5-triazine sodium 30 mg salt

[0133]

Embedded image

(CH ₂ = CHSO ₂ CH ₂ ) ₂ O (hardener) 36 mg or more of the coating liquid is shown in Table 1 on a blue-colored polyethylene terephthalate film base having a thickness of 175 μm and subjected to undercoating treatment. Samples 1 to 15 were prepared by uniformly applying the coating composition on both sides and drying. The dyes shown in Table 1 were dispersed by the following method.

Dispersion Method Water and a surfactant alkanol XC (alkylnaphthalene-sulfonate: manufactured by DuPont) were put in a ball mill container, each dye to be added was added, and zirconium oxide beads were put and the container was closed. Disperse in ball mill for days.

Then, an aqueous gelatin solution is added and mixed for 10 minutes, and the beads are removed to obtain a coating solution.

[0137]

[Table 1]

(Production of Fluorescent Intensifying Screen 1) Phosphor Gd ₂ O ₂ S: Tb (Average particle size 1.8 μm) 200 g Binder Polyurethane thermoplastic elastomer Demolac TPKL-5-2625 Solid content 40% (Sumitomo Bayer Urethane Co., Ltd.) 20 g Nitrocellulose (digestibility 11.5%) 2 g Methyl ethyl ketone solvent was added to the above and dispersed by a propeller mixer to prepare a coating liquid for forming a phosphor layer having a viscosity of 25 ps (25 ° C.). (Binder / phosphor ratio = 1/22) Separately, a soft acrylic resin solid content is used as a coating liquid for forming the undercoat layer.
Methyl ethyl ketone was added to 90 g and nitrocellulose 50 g to disperse and mix them to prepare a dispersion having a viscosity of 3 to 6 ps (25 ° C.).

A 250 μm-thick polyethylene terephthalate base (support) in which titanium dioxide was kneaded was placed horizontally on a glass plate, and the above coating solution for forming the undercoat layer was uniformly applied on the support using a doctor blade. From 25 ℃
The coating film was dried by gradually raising the temperature to 100 ° C. to form an undercoat layer on the support. The thickness of the coating film was 15 μm.

Onto this, the above-mentioned phosphor layer forming coating liquid was uniformly applied and dried to a thickness of 150 μm using a doctor blade, and then compressed. The compression was performed using a calender roll at a pressure of 300 kgw / cm ² and a temperature of 80 ° C. After this compression, a transparent protective layer having a thickness of 3 μm was formed by the method described in Example 1 of JP-A-6-75097.

As described above, a fluorescent intensifying screen 1 comprising a support, an undercoat layer, a phosphor layer and a protective layer was produced.

(Production of Fluorescent Intensifying Screen 2) Fluorescent intensifying screen 1 is produced in the same manner as in the production of fluorescent intensifying screen 1, except that the coating liquid for forming the phosphor layer is applied in a thickness of 150 μm and no compression is performed. A radiation fluorescent intensifying screen 2 comprising a support, an undercoat layer, a phosphor layer and a protective layer was produced in the same manner as in.

(Measurement of Characteristics of Radiation Fluorescent Intensifying Screen) 1) Measurement of Sensitivity MRE single-sided silver halide photographic light-sensitive material manufactured by Eastman Kodak Co., Ltd. is placed in front of the radiation fluorescent intensifying screen to be measured against the X-ray source The photosensitive material and then the fluorescent intensifying screen are placed in contact with each other, and the X-ray exposure amount is changed by the distance method.
Stepwise exposure was performed with a width of 0.15. The exposed silver halide photographic light-sensitive material was subjected to development processing by the method described in the measurement of characteristics of silver halide photographic light-sensitive material described later to obtain a measurement sample.

2) Measurement of X-ray Absorption Amount of X-ray generated from a tungsten target tube corresponding to 2.2 mm of aluminum with intrinsic filtration operated at 80 KVp by supplying three-phase power is transmitted through an aluminum plate having a thickness of 3 mm. , Reach the sample radiation fluorescent intensifying screen fixed at a position 200 cm from the tungsten anode of the target tube, and then the X-ray dose transmitted through the fluorescent intensifying screen at a position 50 cm after the phosphor layer of the fluorescent intensifying screen. Dose measurement using an ionization type dosimeter, X
The amount of line absorption was determined. As a reference, the X-ray dose at the measurement position measured without passing through the fluorescent intensifying screen was used.

Table 2 shows the measured values of the X-ray absorption amount of each of the obtained fluorescent intensifying screens.

[0146]

[Table 2]

(Evaluation of Sensitivity of Photosensitive Material) Using a filter having the spectral characteristic shown in FIG. 1, a tungsten light source having a color temperature of 2856K (the light of 545 nm by the filter [the main emission wavelength of the radiation fluorescent intensifying screen to be used together later) Was used as irradiation light and SR-G (manufactured by Konica Corporation) was exposed as a sample for comparison and a sample for comparison, and its sensitivity was measured. That is, 1 /
The sample light-sensitive material was irradiated for 25 seconds to be exposed.

After the exposure, the photosensitive material of the sample is processed by the automatic processor FP.
A development process was performed on the M-5000 (manufactured by Fuji Photo Film Co., Ltd.) at 35 ° C. for 25 seconds (total processing time 90 seconds) with the developer described above. After peeling off the photosensitive layer on the surface opposite to the exposed surface, the density was measured to obtain a characteristic curve. The exposure amount required to reach the minimum density +0.5 was calculated from the characteristic curve, and the sensitivity is shown in Table 2 as "lux seconds". In calculating the exposure dose, the illuminance of light emitted from a tungsten light source and transmitted through the above-mentioned filter was measured with an IM-3 illuminometer (manufactured by Topcon Corporation).

<Evaluation of Sensitometry> The obtained photosensitive material sample was sandwiched between fluorescent intensifying screens 1 and 2, and penetrometer B was used.
After X-ray irradiation through the mold (made by Konica Medical) SRX-503
Using an automatic processor, the SR-DF processing solution was used for processing at a developing temperature of 35 ° C. for a total processing time of 45 seconds. (Both manufactured by Konica) At this time, the replenishment amount of the processing solution is 210 m for both the developing solution and the fixing solution.
It was set to l / m ² .

The sensitivity was shown as a relative value with the reciprocal of the X-ray exposure amount required to obtain the density of Sample 1 being the minimum density of +1.0 as 100.

The results are shown in Table 3.

<Evaluation of ultra-rapid processability> After each sample was sandwiched with the fluorescent intensifying screen 1 and irradiated with X-rays in the same manner as in the evaluation of sensitometry.
The SRX-503 automatic processor was modified so that the processing time was as follows, and the processing was performed with the SR-DF processing solution at a developing temperature of 35 ° C. The replenishing amount of the processing solution was 125 ml / m ² for both the developing solution and the fixing solution.

Table 3 shows the sensitivities at this time.

Development time: 8 seconds Fixing time: 6.3 seconds Water washing time: 3.4 seconds Water washing-drying (squeeze): 2 seconds Drying time: 5.3 seconds Total processing time: 25
Second, the evaluation of the drying property with an automatic processor was performed as follows. Large-angle size (35.6 × 35.6 x) exposed using the above automatic processor and processing agent so that the density after development processing will be about 1.0.
70 samples of 35.6 cm) were continuously processed. Subsequently, five samples for evaluation were similarly treated continuously, and the sample film immediately after the completion of drying was evaluated by touch.

The drying air temperature was 50 ° C.

The evaluation criteria are as follows.

A: It is completely dry (dry state) B: There is a slightly moist part (substantially usable level) C: It is moist and sticks when the films are overlapped D: Painted < Evaluation of scratch resistance> Each sample was kept under constant temperature and humidity of 23 ° C and relative humidity of 42% for about 1 hour, and under this condition, a commercially available nylon scrubbing brush was used to rub a load of 100 g / cm2. After that, it was developed with the above-mentioned automatic developing machine while being unexposed and visually evaluated.

The evaluation criteria are as follows.

A: Almost no scratches B: Practically no problem, but some scratches C: Scratches are noticeable and practically problematic D: Very many scratches, width of scratches Thick and dense density <Evaluation of sharpness and graininess> For each fluorescent intensifying screen / photosensitive material combination evaluated for sensitivity, a Kyoto Kagaku chest phantom with 120 KVp (3 mm thick aluminum equivalent filter attached) X-ray Using a source, a phantom was placed at a distance of 140 cm, an anti-scattering grid with a grid ratio of 8: 1 was placed behind it, and a light-sensitive material and a fluorescent intensifying screen were placed behind it to take pictures.

In each of the photographs, the X-ray exposure amount was adjusted by changing the exposure time so that the highest density portion of the lung field was 1.8 ± 0.5. The obtained photograph was visually observed, and the graininess and sharpness were evaluated according to the following evaluation criteria.

Graininess Evaluation Criteria A: Almost inconspicuous B: Slightly conspicuous C: Slightly obstructive in interpretation of images D: Very conspicuous in obstruction of interpretation of images Sharpness evaluation criterion A: Very sharp B: Good but slightly blurred Yes C: Blurring is noticeable and there is some difficulty in interpretation. D: Interpretation is difficult due to blur

[0162]

[Table 3]

From the above results, the light-sensitive material of the present invention has high sensitivity, high image quality, excellent pressure resistance, and ultra-rapid processing property.
Excellent in sensitivity and dryness.

[0164]

According to the present invention, it is possible to provide a silver halide photographic light-sensitive material and an X-ray image forming method which have high sensitivity, high image quality, excellent scratch resistance, and excellent ultra-rapid processability.

[Brief description of drawings]

FIG. 1 is a spectrum curve showing characteristics of a green filter used in combination with a tungsten light source for sensitivity measurement of a silver halide photographic light-sensitive material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G03C 5/26 G03C 5/26 5/30 5/30 G21K 4/00 G21K 4/00 A

Claims (6)

[Claims] 1. A silver halide photographic light-sensitive material having two or more light-sensitive silver halide emulsion layers on each side of a transparent support, wherein the silver halide emulsion layer closest to the support has a wavelength of 520 to 560 nm. Containing a dye in the solid dispersion state having a maximum absorption wavelength between them, and the average grain size of silver halide grains contained in the silver halide emulsion layer is the same as that of the silver halide emulsion layer on the same side. A silver halide photographic light-sensitive material characterized in that the average grain size of silver halide grains contained in a silver emulsion layer is 80% or less. 2. In the above silver halide photographic light-sensitive material, the silver coverage of the silver halide emulsion layer closest to the support is the same as the silver coverage of silver halide emulsion layers other than the silver halide emulsion layer on the same side. 50% or less of the silver halide photographic light-sensitive material according to claim 1. 3. In the silver halide photographic light-sensitive material, 50% or more of the total projected area of silver halide grains contained in the emulsion layer farthest from the support has an aspect ratio of 3
It is above, The silver halide photographic light-sensitive material of Claim 1 or 2 characterized by the above. 4. A fluorescent sensitization which shows an absorption amount of 45% or more for X-rays having an X-ray energy of 80 KVp, a filling rate of the phosphor of 68% or more, and a thickness of the phosphor of 135 μm or more and 200 μm or less. An X-ray image forming method, wherein imagewise exposure is performed by irradiating paper with X-rays sandwiching the silver halide photographic light-sensitive material according to claim 1, 2 or 3. 5. The X-ray image forming method according to claim 4, wherein the sensitivity of the silver halide photographic light-sensitive material has the same wavelength as the main emission peak wavelength of the fluorescent intensifying screen, and the full width at half maximum is Exposure required to achieve a minimum density of ± 0.5 when exposed with monochromatic light of 15 ± 5 nm and developing with the developer of the following composition at a developer temperature of 35 ° C and a developing time of 25 seconds. An X-ray image forming method, characterized in that it has a sensitivity of 0.027 lux seconds to 0.040 lux seconds. Developer composition potassium hydroxide 21g potassium sulfite 63g boric acid 10g hydroquinone 26g triethylene glycol 16g 5-methylbenzotriazole 0.06g 1-phenyl-3-mercaptotetrazole 0.01g glacial acetic acid 12g 1-phenyl-3-pyrazolidone 1.2g glutaraldehyde 5g Potassium bromide 4g After adding water to make 1 liter, adjust the pH to 10.0. 6. The total processing time of the silver halide photographic light-sensitive material according to claim 1, 2 or 3 is 40 using an automatic processor.
The X-ray image forming method according to claim 4, wherein the processing is performed in seconds or less.