JP2003248095A - Radiation image conversion panel and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation image conversion panel having high brightness and little image unevenness. <P>SOLUTION: In producing the radiation image conversion panel, having a stimulable phosphor layer containing stimulable phosphor dispersed in polymer resin on a support body, a phosphor sheet made by spreading the stimulable phosphor layer on the support body is dried and preheated to 30°C to 150°C, pressed and then compressed in a processing. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation image conversion panel using a stimulable phosphor and a method for manufacturing the same, and more specifically, a radiation image conversion panel having excellent brightness and less image unevenness and a method for manufacturing the same. It is about.

[0002]

2. Description of the Related Art Radiation images such as X-ray images are widely used in the fields of disease diagnosis and the like. This X-ray image can be obtained by irradiating the phosphor layer (fluorescent screen) with X-rays that have passed through the subject to generate visible light, which is the same as when taking a normal photo. Then, a so-called radiographic method is widely used in which a silver halide photographic light-sensitive material is irradiated and then developed to obtain a visible silver image.

However, in recent years, a new method of directly taking out an image from a phosphor layer has been proposed instead of an image forming method using a light-sensitive material having a silver halide salt.

As this method, the radiation that has passed through the subject is absorbed by the phosphor, and then the phosphor is excited by, for example, light or thermal energy, so that the radiation energy accumulated by the phosphor is absorbed. Then, there is a method of detecting this fluorescence and imaging it.

Specifically, for example, US Pat. No. 3,85
A radiation image conversion method using a stimulable phosphor (hereinafter, also simply referred to as a phosphor) as described in JP-A No. 9,527 and JP-A No. 55-12144 is known.

This method uses a radiation image conversion panel containing a stimulable phosphor, and the radiation transmitted through the object is applied to the stimulable phosphor layer of the radiation image conversion panel to apply the radiation to each part of the object. Accumulates radiation energy corresponding to the radiation transmission density, and then accumulates in the stimulable phosphor by time-sequentially exciting the stimulable phosphor with electromagnetic waves (excitation light) such as visible light and infrared rays. The emitted radiation energy is emitted as stimulated emission, and the signal due to the intensity of this light is photoelectrically converted to obtain an electric signal, and this signal is recorded, such as a recording material such as a silver halide photographic light-sensitive material, a CRT, etc. Is reproduced as a visible image on the display device.

According to the above radiographic image reproducing method, compared with the conventional radiographic method using a combination of a radiographic film and an intensifying screen, the radiographic image has a much smaller exposure dose and a rich information content. Has the advantage that

As described above, the stimulable phosphor is a phosphor that exhibits stimulated emission when irradiated with excitation light after being irradiated with radiation, but in practice, excitation with a wavelength in the range of 400 to 900 nm is used. A phosphor that emits stimulated emission in the wavelength range of 300 to 500 nm by light is generally used.

A radiation image conversion panel using these stimulable phosphors releases radiation energy by scanning excitation light after storing radiation image information. Therefore, radiation images can be stored again after scanning. It can be used repeatedly. In other words, in the conventional radiographic method, the radiographic film is consumed for each photographing, whereas in the radiographic image conversion method, the radiographic image conversion panel is repeatedly used. It is advantageous.

The superiority or inferiority of the radiation image conversion system using the radiation image conversion panel is greatly influenced by the stimulable emission luminance (also referred to as sensitivity) of the panel and the image quality represented by the obtained graininess and sharpness. Many of the characteristics of (3) are greatly influenced by the characteristics of the stimulable phosphor used and the form of the stimulable phosphor layer. Specifically, the emission intensity of the radiation image conversion panel, the sharpness of the image, the granularity, etc. depend on the size of the phosphor particles, the dispersibility of the phosphor, the uniformity of the phosphor, the filling rate, etc. The body filling rate has a great influence.

As a means for improving the filling rate, Japanese Patent Laid-Open No. 3-2 is known.
No. 1898, glass transition point (hereinafter, also referred to as Tg) 30
Using resin of ~ 150 ° C, the filling rate of stimulable phosphor is 7
A radiation image conversion panel of 0% or more is disclosed, and compression of a phosphor layer (hereinafter, also simply referred to as a coating film) is shown as a means for achieving it. Since the radiation image conversion panel is rubbed against the film or roll under room temperature conditions during use, it is considered that the Tg of the binder resin used is preferably 30 ° C. or higher. However, when a resin having a high Tg is used as the binder resin, the coating film is less likely to be deformed during drying and the filling rate is less likely to increase. Further, when the resulting coating film is compressed, the softening property of the resin is poor, so that the fluorescent substance is loaded and the emission of light is reduced due to the destruction of the crystal structure of the luminous body. In addition, there is a problem in that the compression temperature needs to be increased in order to soften the resin and productivity is deteriorated.

Further, Japanese Patent Publication No. 4-44719 discloses 50
A method for improving the filling rate of the phosphor layer by performing compression treatment at a temperature of ℃ or more is disclosed, but by simply passing pressure between heating rolls at a temperature of 50 ℃ or more,
Since the compression treatment is performed by heating and pressurizing at the same time, the desired compressibility cannot be obtained, or by applying excessive temperature and pressure, the phosphor layer may be deformed or destroyed, resulting in , High brightness is not obtained,
Image unevenness occurs during image reading, which may cause a fatal problem in diagnosis, and urgent improvement is required.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to obtain high brightness.
Another object of the present invention is to provide a radiation image conversion panel with less image unevenness and a manufacturing method thereof.

[0014]

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

1. In a method for producing a radiation image conversion panel having a stimulable phosphor layer containing a stimulable phosphor dispersed in a polymer resin on a support, the stimulable phosphor layer is provided on the support. Apply and dry the phosphor sheet at 30 ℃
As described above, the method for producing a radiation image conversion panel is characterized in that, in a state of being preheated at 150 ° C. or less, the compression treatment is performed by heating and pressurizing under conditions of 30 ° C. or more and 150 ° C. or less.

2. The applied pressure is 100 N / c as a linear pressure.
m or more and 5 kN / cm or less, The manufacturing method of the radiation image conversion panel of said 1 characterized by the above-mentioned.

3. A radiation image conversion panel manufactured by the method for manufacturing a radiation image conversion panel according to the item 1 or 2.

4. The stimulable phosphor is Eu-added BaF.
The radiation image conversion panel according to the above item 3, which is an I compound.

As a result of extensive studies in view of the above problems, the present inventor has found that a radiation image having a stimulable phosphor layer containing a stimulable phosphor dispersed in a polymer resin on a support. In the method for manufacturing a conversion panel, a phosphor sheet obtained by applying the stimulable phosphor layer onto a support and drying the phosphor sheet at 30 ° C. or higher is used.
By pre-heating at 150 ° C. or lower and subsequently performing compression treatment by heating and pressurizing under conditions of 30 ° C. or higher and 150 ° C. or lower, flexibility of the phosphor layer at the time of compression treatment is increased, and It has been found that it is possible to obtain a radiation image conversion panel that can be compressed with a reduced load, and as a result, has a high compression rate, high brightness, and improved image unevenness.

In addition, by setting the pressure during the compression treatment to a linear pressure of 100 N / cm or more and 5 kN / cm or less, or by using an Eu-added BaFI compound as the stimulable phosphor, the above-mentioned effect is further enhanced. The present invention has been found to be further exerted, and the present invention has been completed.

The details of the present invention will be described below. In the invention according to claim 1, in the method for producing a radiation image conversion panel having a stimulable phosphor layer containing a stimulable phosphor dispersed in a polymer resin on a support, the stimulable Apply the phosphor layer on the support, dry the phosphor sheet,
When preheated above 30 ℃ and below 150 ℃,
The feature is that the compression treatment is performed by heating and pressurizing at a temperature of not less than 0 ° C and not more than 150 ° C.

First, the preheating and compression treatment according to the present invention will be described. The present invention is characterized in that a stimulable phosphor layer is coated on a support, dried to form a phosphor sheet, and then preheated before compression treatment.

FIG. 1 is a schematic view showing an example of the manufacturing flow of the radiation image conversion panel (phosphor sheet) of the present invention.

In FIG. 1, first, a stimulable phosphor layer coating liquid is applied by a coater 3 to a support 1 which is fed from a supply roll 2 in a conveying direction D, and then a drying zone 4 is applied.
Then, hot air is blown from the nozzles arranged above and below to dry. Next, the dried support 1 (or phosphor sheet) on which the stimulable phosphor layer has been applied is heated to 30 to 150 ° C. by the preheater 5 in the preheating section, and then the temperature is maintained. In this state, the compression processing unit composed of the heating roll 6 and the pressure roll 7 performs processing, and the winding roll 8 winds it up.

FIG. 2 is an enlarged view of the preheating section and the compression processing section. In the present invention, it is preferable that the preheating and compression processing section horizontally conveys and processes the phosphor sheet 1.

The preheater 5 used in the preheating section is not particularly limited as long as it can uniformly heat the surface of the support to be conveyed, and as the heat source, for example, an infrared heater or a ceramic heater can be used.

Next, the compression processing step will be described. The compression treatment of the phosphor sheet referred to in the present invention means coating a stimulable phosphor layer on a support or a support provided with an undercoat layer,
After drying under desired conditions, a stimulable phosphor layer is formed into a phosphor sheet, and after passing through the above preheating section, for example, a calender roll, or a pressure roll and heatable heating facing it. It refers to treatment by applying temperature and pressure using a roll. In the present invention, it is preferable to use the latter method.

In the present invention, by performing this compression treatment, the first effect is that the filling rate of the stimulable phosphor in the stimulable phosphor layer can be improved, resulting in high emission brightness and sharpness. The second effect is that by applying specific pressure and heating conditions, it is possible to obtain high uniformity of the phosphor sheet during the compression treatment.

There are no particular restrictions on the compression method that can be used in the present invention, but for example, "Handbook of Resin Processing Technology (Polymer Society of Japan): Nikkan Kogyo Shimbun, June 12, 1965. Can be applied with reference to the method described in.

The heating and pressure rolls that can be used in the present invention include, for example, a heating roll, a cored bar made of aluminum or the like, and a coating layer or surface made of a hard resin or the like on the cored bar if necessary. Layers are provided. A heating means, for example, a halogen heater or the like is provided inside the heating roll, and the temperature during the compression treatment is controlled to a predetermined temperature of 30 to 150 ° C. The heating roll is rotated by a driving force transmitted through a gear by a motor or the like, and the pressure roll is driven to rotate accordingly.

On the other hand, the pressure roll is provided with a cored bar made of aluminum or the like, and a coating layer and a surface layer on the cored bar as required.

As a compression treatment method using a calender roll, for example, the calender roll may have a single structure, or a plurality of calender rolls may be used in parallel for processing. There is no limitation on the structure of the calender roll or the type of resin, but examples thereof include a high-rigidity base body using an iron material as an inner core and a roller whose outer peripheral surface is covered with, for example, an outer cylinder made of a hard resin. Examples thereof include Ellagras (manufactured by Kinyo Metal Co., Ltd.) and Mirrortex Roll (manufactured by Yamauchi Rubber Co., Ltd.).

In the invention according to claim 2, it is preferable that the pressure during the compression treatment is a linear pressure of 100 N / cm to 5 kN / cm, preferably a linear pressure of 1 to 4 kN / cm.
The condition is cm. By performing the compression condition in the range defined above, the filling rate of the stimulable phosphor layer, the smoothness is improved, as a result, image unevenness of the stimulable phosphor is reduced,
Good sharpness can be obtained. In particular, under the above conditions, the compressibility of the phosphor layer near the support is increased, which is preferable.

Under the above conditions, the linear pressure is 100 N /
If the temperature is less than 30 cm and the temperature is 30 ° C. or less, sufficient compressibility and smoothness cannot be obtained, and the linear pressure is 5 kN / cm or more,
When the temperature is 150 ° C. or higher, the stimulable phosphor particles may be destroyed and the support may be deformed, which is not preferable.

Next, each component of the radiation image conversion panel of the present invention will be described. The stimulable phosphor that can be used in the present invention has a wavelength of 400 to 900 nm.
Phosphors that exhibit stimulated emission in the wavelength range of 300 to 500 nm with excitation light in the range are generally used.

Examples of phosphors that can be preferably used in the radiation image conversion panel of the present invention will be given below, but the present invention is not limited thereto.

(1) (Ba _1-X , M (II) _X ) FX: yA described in JP-A-55-12145 (wherein
M (II) is at least one of Mg, Ca, Sr, Zn and Cd, X is at least one of Cl, Br and I, A is Eu, Tb, Ce, Tm, Dy, P
At least one of r, Ho, Nd, Yb, and Er, and 0 ≦ x ≦ 0.6, y is 0 ≦ y ≦ 0.
2) The rare earth element-activated alkaline earth metal fluorohalide phosphor represented by the composition formula; The phosphor may further contain the following additives.

A) X ', BeX ", M (III) X'" ₃ , described in JP-A-56-74175, wherein
X ′, X ″, and X ′ ″ are at least one of Cl, Br, and I, respectively, and M (III) is a trivalent metal. B) Be described in JP-A-55-160078.
O, MgO, CaO, SrO, BaO, ZnO, Al ₂
O ₃ , Y ₂ O ₃ , La ₂ O ₃ , In ₂ O ₃ , SiO ₂ , Ti
O ₂ , ZrO ₂ , GeO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅
And metal oxides such as ThO ₂ c) Z described in JP-A-56-116777
r, Sc d) Be described in JP-A-57-23673, As) described in JP-A-57-23675,
Sif) M. described in JP-A-58-206678
L, in the formula, M is at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs, and L is Sc, Y, La, Ce, Pr, Nd, Pm, S.
m, Gd, Tb, Dy, Ho, Er, Tm, Yb, L
g) at least one trivalent metal selected from the group consisting of u, Al, Ga, In, and Tl) A fired product of a tetrafluoroboric acid compound described in JP-A-59-27980; 59-2728
Calcinated products of monovalent or divalent metal salts of hexafluorosilicic acid, hexafluorotitanic acid and hexafluorozirconic acid described in JP-A No. 59-56.
NaX 'described in Japanese Patent No. 479, wherein X'is C
at least one of l, Br and I h) V and C described in JP-A-59-56480
Transition metals such as r, Mn, Fe, Co and Ni; M (I) X 'described in JP-A-59-75200.
M '(II) X " ₂ , M (III) X'" ₃ , A, in the formula, M
(I) is at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs,
M '(II) represents at least one divalent metal selected from the group consisting of Be and Mg, and M (III) represents Al, G
at least one trivalent metal selected from the group consisting of a, In, and Tl, A is a metal oxide,
X ', X "and X'" are each at least one halogen selected from the group consisting of F, Cl, Br and I i) M described in JP-A-60-101173
(I) X ′, wherein M (I) is at least one alkali metal selected from the group consisting of Rb and Cs,
X'is at least one halogen selected from the group consisting of F, Cl, Br and I. j) M (I) described in JP-A No. 61-23679.
I) ′ X ′ ₂ · M (II) ′ X ″ ₂ , where M (II) ′ is B
at least one alkaline earth metal selected from the group consisting of a, Sr and Ca; X ′ and X ″ are at least one halogen selected from the group consisting of Cl, Br and I, and X ′. ≠ X ″;
Further, LnX ″ ₃ described in JP-A-61-264084, in which Ln is Sc, Y, La, Ce,
Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, E
at least one rare earth element selected from the group consisting of r, Tm, Yb and Lu; X ″ is F, Cl, Br
And at least one halogen selected from the group consisting of I and I.

(2) M (II) X ₂ · aM (II) X ′ ₂ : xEu ^{2+ described in} JP-A-60-84381 (wherein M (II) is Ba, Sr or Ca) Is at least one alkaline earth metal selected from the group consisting of; X and X'are at least one halogen selected from the group consisting of Cl, Br and I, and X ≠ X '; and a Is 0.1 ≦ a ≦ 10.0, x is 0 <x ≦
0.2) The divalent europium-activated alkaline earth metal halide phosphor represented by the composition formula; and the phosphor may contain the following additives.

A) M (I) X 'described in JP-A-60-166379, wherein M (I) is Rb and C
at least one alkali metal selected from the group consisting of s; X'is at least one halogen selected from the group consisting of F, Cl, Br and I. b) Described in JP-A-60-221483. K
X ″, MgX ″ ″ ₂ , M (III) X ″ ″ ₃ , where M (II
I) is at least one trivalent metal selected from the group consisting of Sc, Y, La, Gd and Lu; X ″,
X ′ ″ and X ″ ″ are all F, Cl, Br and I
At least one halogen selected from the group consisting of c) B described in JP-A-60-228592,
Si described in JP-A-60-228593
O _2, P ₂ O ₅ oxide such, LiX listed in JP 61-120882 ", NaX", in the formulas, X "at least selected from the group consisting of F, Cl, Br and I D) a kind of halogen Si described in JP-A-61-120883
O: Sn described in JP-A-61-120885
X ″ ₂ , where X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I. e) Cs described in JP-A-61-235486
X ″, SnX ″ ″ ₂ , where X ″ and X ′ ″ are at least one halogen selected from the group consisting of F, Cl, Br and I; and JP-A-61-23.
CsX ″, Ln ³⁺ , in the formula:
X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I; Ln is Sc, Y, C
e, Pr, Nd, Sm, Gd, Tb, Dy, Ho, E
It is at least one rare earth element selected from the group consisting of r, Tm, Yb and Lu.

(3) LnOX: xA described in JP-A-55-12144 (wherein Ln is La, Y, G
at least one of d and Lu; X is Cl, B
at least one of r and I; A is Ce and T
At least one of b; x is 0 <x <0.1) A rare earth element-activated rare earth oxyhalide phosphor represented by a composition formula.

(4) M (II) OX: xCe described in JP-A-58-69281 (wherein M (II) is P
r, Nd, Pm, Sm, Eu, Tb, Dy, Ho, E
at least one metal oxide selected from the group consisting of r, Tm, Yb, and Bi; X is at least one of Cl, Br, and I; x is 0 <x <0.1
Is a cerium-activated trivalent metal oxyhalide phosphor.

(5) M (I) X: xBi described in JP-A-62-25189 (wherein M (I) is at least one alkali metal selected from the group consisting of Rb and Cs). X is at least one halogen selected from the group consisting of Cl, Br and I; and x is a numerical value in the range of 0 <x ≦ 0.2). Metal halide phosphor.

(6) M (II) ₅ (PO ₄ ) ₃ X: xEu ²⁺ described in JP-A-60-141783 (wherein
M (II) is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba; X is F,
A divalent europium-activated alkaline earth metal haloline represented by the composition formula: at least one halogen selected from the group consisting of Cl, Br and I; x is a numerical value in the range of 0 <x ≦ 0.2. Phosphate phosphor.

(7) M (II) ₂ BO ₃ X: xEu ²⁺ (in the formula, M (I
I) is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba; X is Cl, B
a divalent europium-activated alkaline earth metal haloborate represented by the composition formula: at least one halogen selected from the group consisting of r and I; x is a numerical value in the range of 0 <x ≦ 0.2. Phosphor.

(8) M (II) ₂ (PO ₄ ) ₃ X: xEu ²⁺ described in JP-A-60-157100 (wherein
M (II) is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba; X is C
a divalent europium-activated alkaline earth metal haloline represented by the composition formula: at least one halogen selected from the group consisting of 1, Br and I; x is a numerical value in the range of 0 <x ≦ 0.2. Phosphate phosphor.

(9) M (II) HX: xEu ²⁺ described in JP-A-60-217354 (wherein M (II) is at least one selected from the group consisting of Ca, Sr and Ba) Alkaline earth metal; X is at least one halogen selected from the group consisting of Cl, Br and I; x is a numerical value in the range of 0 <x ≦ 0.2) Divalent europium activated alkaline earth metal hydrohalide phosphor.

(10) LnX ₃ .aLn'X ' ₃ : xCe ³⁺ described in JP-A-61-211173 (wherein Ln and Ln' are each of Y, La, Gd and Lu). At least one rare earth element selected from the group; X and X'each being at least one halogen selected from the group consisting of F, Cl, Br and I, and X ≠ X '; and a is 0.1 <a
A numerical value in the range of ≦ 10.0, and x is a numerical value in the range of 0 <x ≦ 0.2).

[0049] (11) LnX ₃ · aM that are described in ^{JP-A-61-21182 (I) X'3: xCe 3+} ,
(In the formula, Ln is at least one rare earth element selected from the group consisting of Y, La, Gd, and Lu; M
(I) is at least one alkali metal selected from the group consisting of Li, Na, K, Cs and Rb; X and X ′ are at least one halogen selected from the group consisting of Cl, Br and I, respectively. And a is a numerical value in the range of 0 <a ≦ 10.0, and x is 0 <x ≦
A cerium-activated rare-earth composite halide-based phosphor represented by a composition formula of 0.2).

(12) LnPO ₄ .aLnX ₃ : xCe ³⁺ described in JP-A-6140390 (wherein
Ln is at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; X is F, Cl,
At least one halogen selected from the group consisting of Br and I; and a is a numerical value in the range of 0.1 ≦ a ≦ 10.0 and x is a numerical value in the range of 0 <x ≦ 0.2. ) A cerium-activated rare earth halophosphate phosphor represented by the composition formula (1).

(13) CsX: aRbX ': xEu ²⁺ described in JP-A-61-2336888,
(Wherein X and X ′ are at least one halogen selected from the group consisting of Cl, Br and I respectively; and a is a numerical value in the range of 0 <a ≦ 10.0,
x is a numerical value in the range of 0 <x ≦ 0.2), which is a divalent europium-activated cesium rubidium halide phosphor represented by the composition formula.

(14) M (II) X ₂ .aM (I) X ': xE described in JP-A-61-236890.
u ²⁺ , where M (II) is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; M (I) is selected from the group consisting of Li, Rb and Cs At least one alkali metal; X and X ′ are each at least one halogen selected from the group consisting of Cl, Br and I; and a is a numerical value in the range of 0.1 ≦ a ≦ 20.0. , X is 0 <x
A divalent europium-activated composite halide phosphor represented by the composition formula: ≦ 0.2).

Among the above stimulable phosphors, it is preferable that the stimulable phosphor particles contain iodine, for example, a divalent europium-activated alkaline earth metal fluoride halide system containing iodine. Phosphor, divalent europium-activated alkaline earth metal halide phosphor containing iodine, rare earth element-activated rare earth oxyhalide phosphor containing iodine, and bismuth-activated alkali metal halide phosphor containing iodine Is preferable because it exhibits high-intensity stimulated emission. In the invention according to claim 4,
The photostimulable phosphor is characterized in that it is a Eu-added BaFI compound.

There is no particular limitation on the polymer resin as the binder which can be used in the present invention, and examples thereof include polyurethane, polyester, vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-chloride. Vinylidene copolymer, vinyl chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (nitrocellulose, etc.), styrene-butadiene copolymer, various synthetic rubber resins, phenol resin , Epoxy resin, urea resin, melamine resin, phenoxy resin, silicone resin, acrylic resin, urea formamide resin and the like. Among these, polyurethane, polyester,
It is preferable to use a vinyl chloride copolymer or the like.

The crosslinking agent that can be used in the present invention is not particularly limited, and examples thereof include polyfunctional isocyanates and their derivatives, melamine and its derivatives, amino resins and their derivatives, and the like.
A polyfunctional isocyanate compound is used as a cross-linking agent. For example, Coronate H manufactured by Nippon Polyurethane Co., Ltd.
X, Coronate 3041 and the like.

In the present invention, the polymer resin and the cross-linking agent are added to a suitable solvent, for example, the solvent used in the preparation of the coating solution for the stimulable fluorescent layer, and this is mixed sufficiently to prepare a coating solution.

The amount of the cross-linking agent used varies depending on the characteristics of the intended radiation image conversion panel, the type of material used for the stimulable phosphor layer and the support, the type of polymer resin used for the undercoat layer, etc. Considering the maintenance of the adhesive strength of the stimulable phosphor layer to the support, 50% by mass relative to the polymer resin
It is preferable to add it at the following ratio, particularly preferably 15 to 50% by mass.

As the support used in the radiation image conversion panel of the present invention, various polymer materials are used. In particular, a material that can be processed into a flexible sheet or web for handling as an information recording material is preferable, and from this point, a cellulose acetate film, a polyester film, a polyethylene terephthalate film, a polyethylene naphthalate film, a polyamide film, a polyimide. Plastic films such as films, triacetate films and polycarbonate films are preferred.

The layer thickness of these supports varies depending on the material of the support used, etc., but is generally 80 μm to 10 μm.
It is 00 μm, and more preferably 80 μm to 500 μm from the viewpoint of handling. The surface of these supports may be a smooth surface, or may be a matte surface for the purpose of improving the adhesiveness with the stimulable phosphor layer.

Further, these supports may be provided with an undercoat layer on the surface on which the stimulable phosphor layer is provided for the purpose of improving the adhesiveness with the stimulable phosphor layer.

In the coating liquid for the stimulable phosphor layer, the mixing ratio of the binder and the stimulable phosphor varies depending on the characteristics of the intended radiation image conversion panel, the kind of the phosphor, etc. The ratio of the binder to 100 parts by mass is 1 to
20 parts by mass is preferable, but from the viewpoint of brightness and sharpness of the obtained radiation image conversion panel, it is preferable that the binder is small, and the range of 2 to 10 parts by mass is more preferable from the viewpoint of easy application.

The organic solvent used for preparing the coating liquid for the stimulable phosphor layer is, for example, methanol, ethanol,
Lower alcohols such as isopropanol and n-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, ketones such as cyclohexanone, esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate and n-butyl acetate, dioxane, ethylene glycol monoethyl Examples thereof include ethers, ethers such as ethylene glycol monomethyl ether, aromatic compounds such as triols and xylols, halogenated hydrocarbons such as methylene chloride and ethylene chloride, and mixtures thereof.

The coating liquid contains a dispersant for improving the dispersibility of the phosphor in the coating liquid, and a binder between the binder and the phosphor in the stimulable phosphor layer after formation. Various additives such as a plasticizer for improving the binding strength may be mixed. Examples of dispersants used for such purpose include phthalic acid, stearic acid, caproic acid, lipophilic surfactants and the like. Examples of plasticizers include phosphoric acid esters such as triphenyl phosphate, tricresyl phosphate, diphenyl phosphate; phthalic acid esters such as diethyl phthalate and dimethoxyethyl phthalate; ethyl phthalyl glycolate and butyl phthalyl butyl glycolate. And a glycolic acid ester such as; and a polyester of triethylene glycol and adipic acid, a polyester of polyethylene glycol and an aliphatic dibasic acid such as a polyester of diethylene glycol and succinic acid, and the like. In addition, a dispersant such as stearic acid, phthalic acid, caproic acid, or a lipophilic surfactant is mixed in the coating liquid for the stimulable phosphor layer for the purpose of improving the dispersibility of the stimulable phosphor particles. Good.

The coating liquid for the stimulable phosphor layer is prepared by, for example, a ball mill, a bead mill, a sand mill, an attritor, a three roll mill, a high speed impeller disperser, and Kady.
It is performed using a mill or a dispersing device such as an ultrasonic dispersing machine.

The coating solution prepared as described above is uniformly applied onto the surface of the undercoat layer to form a coating film. As a coating method that can be used, an ordinary coating means such as a doctor blade, a roll coater, a knife coater, an extrusion coater, a comma coater, or a lip coater can be used.

The coating film formed by the above means is then heated and dried to complete the formation of the stimulable phosphor layer on the undercoat layer. The film thickness of the stimulable phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the type of the stimulable phosphor, the mixing ratio of the binder and the phosphor, etc., but is usually 1
0 to 1000 μm, more preferably 10 to 500
μm.

The phosphor sheet having the stimulable phosphor layer coated on the support is cut into a predetermined size. Although any general method can be used for cutting, a cosmetic cutting machine, a punching machine or the like is preferable in terms of workability and accuracy.

The radiation image conversion panel of the present invention is preferably provided with a protective film (also referred to as a protective film) for physically and chemically protecting the surface of the stimulable phosphor layer. It can be appropriately selected depending on the purpose, use and the like.

As the protective layer provided on the radiation image conversion panel of the present invention, a polyester film or a polymethacrylate having an excitation light absorbing layer having a haze ratio of 5% or more and less than 60% as measured by the method described in ASTM D-1003. A film, a nitrocellulose film, a cellulose acetate film or the like can be used, but a stretched film such as a polyethylene terephthalate film or a polyethylene naphthalate film is preferable as the protective layer in terms of transparency and strength, and further, these From the viewpoint of moisture resistance, a polyethylene terephthalate film or a vapor-deposited film obtained by vapor-depositing a thin film of a metal oxide, silicon nitride or the like on a polyethylene terephthalate film is more preferable.

The haze ratio of the film used in the protective layer can be easily adjusted by selecting the haze ratio of the resin film to be used, and a resin film having an arbitrary haze ratio can be easily obtained industrially. . As a protective film for a radiation image conversion panel, one having a very high optical transparency is supposed. As such a highly transparent protective film material, various plastic films having a haze value in the range of 2 to 3% are commercially available. The preferred haze ratio for obtaining the effect of the present invention is 5%.
Or more and less than 60%, more preferably 10% or more 5
It is less than 0%. If the haze ratio is less than 5%, the effect of eliminating image unevenness and linear noise is low, and if it is 60% or more, the effect of improving sharpness is impaired, which is not preferable.

In the present invention, the film used as the protective layer has an optimum moisture-proof property by laminating a plurality of resin films or vapor-deposited films obtained by vapor-depositing a metal oxide on the resin film, in accordance with the required moisture-proof property. Can be
The moisture permeability is preferably at least 50 g / m ² · day or less in consideration of prevention of moisture deterioration of the stimulable phosphor. The method for laminating the resin film is not particularly limited, and any known method may be used.

Further, by providing the excitation light absorption layer between the laminated resin films, the excitation light absorption layer is protected from physical impact and chemical alteration, and stable plate performance can be maintained for a long time, which is preferable. Further, the excitation light absorption layer may be provided at a plurality of positions, or the adhesive layer for laminating may contain a coloring agent to form the excitation light absorption layer.

The protective film may be adhered to the stimulable phosphor layer through an adhesive layer, but the structure is provided so as to cover the phosphor surface (hereinafter, also referred to as sealing or sealing structure). Is more preferable. In sealing the phosphor plate, any known method may be used, but the outermost resin layer on the side in contact with the phosphor sheet of the moisture-proof protective film is a resin film having heat-sealing property, and it is moisture-proof. This is one of the preferable modes in that the property protection film can be fused and the work of sealing the phosphor sheet can be made efficient.
Furthermore, the moisture-proof protective film is arranged on the upper and lower sides of the phosphor sheet, and the peripheral edge thereof is an area outside the peripheral edge of the phosphor sheet. The sealing structure is preferable because moisture can be prevented from entering from the outer peripheral portion of the phosphor sheet.
Further, the moisture-proof protective film on the support surface side is 1
By using a laminated moisture-proof film obtained by laminating aluminum films having more layers, it is possible to more reliably reduce the ingress of moisture, and this sealing method is also easy in terms of work, which is preferable. In the method of heat fusion with the impulse sealer, heat fusion in a reduced pressure environment is more preferable in terms of preventing displacement of the phosphor sheet in the moisture-proof protective film and eliminating moisture in the atmosphere.

It is preferable that the resin layer, which is the outermost layer having the heat-fusible property, on the side of the moisture-proof protective film in contact with the phosphor surface and the phosphor surface are not adhered. The term "non-adhesive" as used herein means that, even if the phosphor surface is microscopically in point contact with the moisture-proof protective film, the phosphor surface and the moisture-proof protective film are almost discontinuous optically and mechanically. It is a state that can be treated as a body. Further, the above-mentioned resin film having heat-fusible property is a resin film that can be fused by a commonly used impulse sealer, and for example, ethylene vinyl acetate copolymer (EVA), polypropylene (PP) film, polyethylene ( PE) film and the like can be mentioned, but the present invention is not limited thereto.

[0075]

[Production of Radiation Image Conversion Panel 1]

(Preparation of phosphor) In order to synthesize a europium-activated barium fluoroiodide stimulable phosphor precursor, 2780 ml of BaI ₂ aqueous solution (3.6 mol / L) and 27 ml of EuI ₃ aqueous solution (0.15 mol / L) are prepared. Was placed in the reactor. The reaction mother liquor in this reactor was kept warm at 83 ° C. with stirring. Next, ammonium fluoride aqueous solution (8 mol / L)
322 ml was poured into the reaction mother liquor using a roll pump to form a precipitate. Keep warm and stir 2 after injection
The precipitate was aged for a period of time. Next, the precipitate was separated by filtration, washed with ethanol, and then dried in vacuum to obtain europium-activated barium fluoroiodide crystals. In order to prevent changes in particle shape due to sintering during firing, and changes in particle size distribution due to fusion between particles, 0.2% by mass of ultrafine alumina powder was added, and the surface of the crystal was thoroughly stirred with a mixer. Ultra fine particles of alumina were uniformly adhered to the surface. This was filled in a quartz boat and fired in a hydrogen atmosphere in a tube furnace at 850 ° C. for 2 hours, and then classified to prepare a europium-activated barium fluoroiodide phosphor having an average particle size of 4 μm. .

(Preparation of Phosphor Layer Coating Solution) 100 g of the phosphor prepared above and 16.7 g of a polyester resin (manufactured by Toyobo Co., Ltd., Byron 63SS solid content concentration 30%) were mixed with methyl ethyl ketone-toluene (1: 1) mixed solvent. And disperse with a propeller mixer to obtain a viscosity of 2.5-
The phosphor layer coating solution was prepared by adjusting to 3.0 Pa · s.

(Preparation of Phosphor Sheet) <Preparation of Phosphor Sheet 1> Using the phosphor layer coating solution prepared above, using the production line shown in FIG. 1, a doctor blade as a coater and a thickness of 250 μm. On the polyethylene terephthalate support of, the coating width is 10
Coat to a film thickness of 230 μm at 00 mm, and apply 10
After being dried at 0 ° C. for 15 minutes, the phosphor sheet 1 was produced by winding as it was without performing preheating and compression treatment.

<Preparation of Phosphor Sheet 2> In preparation of the above-mentioned phosphor sheet 1, after coating and drying the phosphor layer, it is passed through a compression treatment section composed of a pressure roll and a heating roll as shown in FIG. After performing compression processing, wind it up,
A phosphor sheet 2 was produced.

As for the compression treatment conditions, the phosphor sheet conveyance conditions were as follows: Method A shown in FIG. 2 without preheating, and the compression treatment was performed at a heating temperature of 80 ° C. and a linear pressure of 1 kN / cm. I went there.

<Production of Phosphor Sheet 3> In the production of the above-mentioned phosphor sheet 2, the preheating section provided with a ceramic heater was passed through before the compression treatment, and the conditions were as described below. A phosphor sheet 3 was produced.

The conditions for carrying the phosphor sheet are as follows:
The method A described in FIG. 2 was used, the temperature of the preheating part was 50 ° C., the temperature of the compression treatment part was 80 ° C., and the linear pressure was 1 kN / c.
I went in m.

<Preparation of Phosphor Sheets 4 to 17> Table 1 shows the preheating temperature, the preheating method, the temperature of the compression treatment section and the linear pressure condition according to the methods of the phosphor sheets 2 and 3. In the same manner except that the phosphor sheet 4 is changed to
~ 17 were produced. The contact heating, which is the preheating method described in Table 1, was performed by disposing the same heating roll used in the compression treatment section.

(Preparation of Moisture-Proof Protective Film) As the protective film on the phosphor layer coated surface side of the above prepared phosphor sheets 1 to 17, the following constitution (A) was used.

Structure (A) NY15 /// VMPET12 /// VMPET12 /
// PET12 /// CPP20 NY: Nylon PET: Polyethylene terephthalate CPP: Casting polypropylene VMPET: Alumina-deposited PET (commercially available product: manufactured by Toyo Metallizing Co., Ltd.) μm).

The above "///" means a dry lamination adhesive layer, and the thickness of the adhesive layer is 3.0 μm. The used adhesive for dry lamination is
A two-component reactive urethane adhesive was used.

The protective film on the back surface side of the support of the phosphor sheet is CPP 30 μm / aluminum film 9 μm /
A dry laminated film having a constitution of polyethylene terephthalate (PET) 188 μm was used. In this case, the thickness of the adhesive layer was 1.5 μm, and a two-component reactive urethane adhesive was used.

(Preparation of Radiation Image Conversion Panel) The phosphor sheets 1 to 17 prepared above were cut into squares each having a side of 20 cm, and the peripheral edge portion thereof was depressurized using the above-mentioned moisture-proof protective film. Radiation image conversion panels 1 to 17 were produced by fusion and sealing using an impulse sealer. The distance from the fused portion to the peripheral edge of the phosphor sheet is 1
Fused to have a size of mm. The heater of the impulse sealer used for fusing has a width of 3 mm.

<< Evaluation of Radiation Image Conversion Panel >> Each of the radiation image conversion panels produced as described above was evaluated as follows.

(Measurement of Luminance) For each radiation image conversion panel, the luminance was measured by irradiating the X-ray of a tube voltage of 80 kVp from the rear surface side of the phosphor sheet support, and then the panel was irradiated with He.
-Operated by Ne laser light (633 nm) to be excited, and stimulated emission emitted from the phosphor layer is received by a light receiver (spectral sensitivity S-
(5) Photoelectron multiplier tube, and measure its intensity,
This is defined as brightness, and displayed as a relative value with the brightness of the radiation image conversion panel 1 being 100.

(Evaluation of Image Unevenness) After irradiating each radiation image conversion panel with X-rays having a tube voltage of 80 kVp, the panel was turned to H level.
Excitation is performed by scanning with an e-Ne laser beam (633 nm),
The photostimulated luminescence emitted from the phosphor layer is received by a photodetector (spectral sensitivity S
-5 photoelectron image multiplier) to receive the light and convert it into an electric signal, which is reproduced as an image by an image reproducing device, enlarged by 2 times from the output device and printed out, and the obtained printed image is visually observed. Then, the appearance of image unevenness was evaluated.
Regarding the image unevenness, a five-level rank evaluation from 1 to 5 was performed according to the criteria shown below.

5: No image unevenness 4: Light image unevenness in 1 to 2 places in the plane 3: Light image unevenness in 3 to 4 places in the plane 2: 3 to 4 places in the plane Image unevenness is seen, one of them
Table 2 shows the evaluation results obtained as a result of the image unevenness at 5 or more points in the plane.

[0092]

[Table 1]

As is clear from Table 1, after the photostimulable phosphor layer according to the present invention is applied and dried, the amount defined by the present invention 3
By preheating at 0 ° C. or higher and 150 ° C. or lower, then heating and pressing at 30 ° C. or higher and 150 ° C. or lower to perform compression treatment, high brightness can be obtained and image unevenness of the radiation image conversion panel can be reduced. I was able to confirm. Further, it is understood that the effect is further improved by adopting the linear pressure condition defined in claim 2 of the present invention.

[0094]

According to the present invention, it is possible to provide a radiation image conversion panel having high brightness and less image unevenness, and a manufacturing method thereof.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a manufacturing flow of a radiation image conversion panel (phosphor sheet) of the present invention.

FIG. 2 is an enlarged view showing a preheating unit and a compression processing unit according to the present invention.

[Explanation of symbols]

1 Support (phosphor sheet) 2 supply rolls 3 coaters 4 drying zone 5 preheater 6 heating rolls 7 Pressure roll 8 winding roll

Claims (4)

[Claims] 1. A method for producing a radiation image conversion panel having a stimulable phosphor layer containing a stimulable phosphor dispersed in a polymer resin on a support, wherein the stimulable phosphor layer is used. In a state where the phosphor sheet coated with and dried on a support is preheated at 30 ° C or higher and 150 ° C or lower, 30 ° C or higher,
A method of manufacturing a radiation image conversion panel, which comprises heating and pressurizing under a condition of 150 ° C. or lower to perform compression processing. 2. The pressure is 100 N / cm as a linear pressure.
The radiation image conversion panel manufacturing method according to claim 1, wherein the radiation energy is 5 kN / cm or less. 3. A radiation image conversion panel manufactured by the method for manufacturing a radiation image conversion panel according to claim 1. 4. The stimulable phosphor is Eu-added BaFI.
The radiation image conversion panel according to claim 3, wherein the radiation image conversion panel is a compound.