JP2001141896A - Radiation image conversion panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve dirt prevention capability, humidity prevention capability and durability of radiation image conversion panel. SOLUTION: For a radiation image conversion panel 10 consisting of a support 3, a fluorescent layer 1 of at least stimulable phosphor and a protection film 2 piled on the fluorescent layer 1, fluoride resin film of thickness of 1 μm to 10 μm where a protection film 2 is laminated on the fluorescent body film 1. The light transmittivity against stimulated phosphor light and excited light of wave length of 400 nm to 900 nm of fluoride resin film is made 90% to 100%.

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 used for a radiation image conversion method using a stimulable phosphor.

[0002]

2. Description of the Related Art As an alternative to the conventional radiographic method, for example, a radiation image conversion method using a stimulable phosphor as described in JP-A-55-12145 is known. This method uses a radiation image conversion panel (storage phosphor sheet) containing a stimulable phosphor,
Radiation transmitted through the subject or emitted from the subject is absorbed by the stimulable phosphor of the panel, and then the stimulable phosphor is chronologically irradiated with electromagnetic waves (excitation light) such as visible light and infrared light. By exciting, the radiation energy stored in the stimulable phosphor is emitted as fluorescence (stimulated light), and the fluorescence is photoelectrically read to obtain an electric signal. Based on this, a radiation image of the subject or the subject is reproduced as a visible image. The panel after reading is prepared for the next photographing after the remaining image is erased. That is, the radiation image conversion panel is used repeatedly.

According to this radiographic image conversion method, a radiographic image with a large amount of information can be obtained with a much smaller exposure dose than the radiographic method using a combination of a conventional radiographic film and an intensifying screen. There is an advantage that it can be obtained. Furthermore, in contrast to the conventional radiographic method, which consumes radiographic film for each photographing, the radiographic image conversion method uses the radiographic image conversion panel repeatedly, which is advantageous in terms of resource conservation and economic efficiency. It is.

The radiation image conversion panel used in the radiation image conversion method has, as a basic structure, a support and a stimulable phosphor layer provided on the surface of the support. However,
When the phosphor layer is self-supporting, a support is not necessarily required. The stimulable phosphor layer usually comprises a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state. However, as the stimulable phosphor layer, a layer composed of only an aggregate of the stimulable phosphor without a binder formed by a vapor deposition method or a sintering method is known. Further, there is known a radiation image conversion panel having a stimulable phosphor layer in which a polymer substance is impregnated in a gap between stimulable phosphor aggregates. In any of these phosphor layers, the stimulable phosphor is X
When irradiated with excitation light after absorbing radiation such as radiation, it has the property of stimulating luminescence, so radiation transmitted through a subject or emitted from a subject is proportional to the amount of radiation. Absorbed by the stimulable phosphor layer of the image conversion panel, a radiation image of the subject or the subject is formed on the panel as an accumulated image of radiation energy. This accumulated image can be emitted as stimulated emission light by irradiating the excitation light, and the accumulated image of radiation energy is imaged by photoelectrically reading the stimulated emission light and converting it into an electric signal. It is possible to do.

[0005] A protective film is usually provided on the surface of the stimulable phosphor layer (the surface not facing the support) to protect the phosphor layer from chemical alteration or physical impact. are doing. The protective film is formed by applying a solution prepared by dissolving a transparent organic polymer substance such as a cellulose derivative or polymethyl methacrylate in an appropriate solvent onto the phosphor layer, or polyethylene. An organic polymer film such as terephthalate or a sheet for forming a protective film such as a transparent glass plate is separately formed and provided on the surface of the phosphor layer using an appropriate adhesive, or an inorganic compound is deposited on the phosphor by vapor deposition or the like. Those formed on a layer are known. Among them, a protective film in which an organic polymer film is adhered by lamination has advantages in that it generally has a high adhesive strength to a phosphor layer and can be manufactured by a relatively simple process.

In the practice of the radiation image conversion method, the radiation image conversion panel includes irradiation of radiation (recording of a radiation image), irradiation of excitation light (reading of a recorded radiation image), and irradiation of erasing light (remaining). It is repeatedly used in a cycle of “erasing a radiation image”. The transition of the radiation image conversion panel to each step is performed by a conveying means such as a belt or a roller. After one cycle, the panels are usually stacked and stored. However, when a radiation image conversion panel having a protective film formed by coating as described above is repeatedly used in this manner, the phosphor layer is deteriorated due to moisture absorption, and dirt is formed on the surface of the protective film. The image quality of the radiation image formed by the radiation image conversion panel tends to gradually decrease due to reasons such as adhesion. As with the conventional radiographic method, it is desired that the radiation image conversion panel also has high sensitivity and gives an image with good image quality (sharpness, granularity, etc.). ,
Preventing the adhesion of dirt is an important issue.

As a protective film capable of preventing a decrease in the sensitivity of the radiation image conversion panel due to the above-mentioned moisture absorption of the phosphor layer and contamination of the protective film surface, the present applicant has already proposed polytetrafluoroethylene and polytrifluoride ethylene. Radiation image conversion panel having a protective film made of film (Japanese Patent Laid-Open No. 61-23709)
No. 7).

However, polytetrafluoroethylene is almost opaque, and polytrifluoroethylene is translucent to opaque. For this reason, although it is possible to prevent a decrease in sensitivity due to deterioration of the phosphor layer due to moisture absorption of the phosphor layer and contamination of the surface of the protective film, practical use is not possible in image quality such as initial sensitivity of the radiation image conversion panel. It was almost difficult to get something to offer.

On the other hand, Japanese Patent Application Laid-Open No. 2-193100 discloses that the protective layer is formed of a coating film containing a fluorine-based resin, but because the coating film is a coating film, a film strength as high as that of a polymer resin film is obtained. It was difficult.

[0010]

When the radiation image conversion panel is repeatedly used, the surface of the protective film of the panel repeatedly comes into contact with the surface of an object such as a rubber roller. As a result, dirt tends to adhere to the surface of the protective film. Since this contamination causes deterioration of the finally obtained radiation image or deterioration of the quality of image information relating to the radiation image, further improvement of the antifouling property of the protective film is desired. On the other hand, in order to prevent the phosphor layer from being deteriorated due to moisture absorption, it is preferable that the protective layer has a moisture-proof property.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide a radiation image conversion panel which has anti-fouling properties, moisture-proofing properties and excellent durability. .

[0012]

According to the present invention, there is provided a radiation image conversion panel comprising at least a phosphor layer comprising a stimulable phosphor and a protective film laminated on the phosphor layer. A fluororesin film having a film thickness of 1 μm to 10 μm laminated on the phosphor layer, wherein the fluororesin film has a light transmittance of 90% to 100 for stimulated emission light and excitation light having a wavelength of 400 nm to 900 nm.
%.

The fluororesin film means a film obtained by copolymerizing a fluorine-based monomer such as ethylene tetrafluoride, ethylene trifluoride, or vinyl fluoride with a monomer containing or not containing fluorine.

The thickness of the fluororesin film is 1 μm
To 10 μm, preferably 1 μm to 6 μm, more preferably 1 μm to 4 μm.

The light transmittance is preferably from 90% to 100%, particularly preferably from 92% to 100%.

[0016]

According to the present invention, there is provided a radiation image conversion panel having at least a phosphor layer composed of a stimulable phosphor and a protective film laminated on the phosphor layer. Therefore, a radiation image conversion panel having extremely excellent antifouling property and moistureproof property can be obtained.

The thickness of the fluororesin film is set to 1
μm to 10 μm.
Since the light transmittance with respect to the stimulated emission light and excitation light of from 00 nm to 900 nm is from 90% to 100%, it is possible to obtain a radiation image conversion panel that is satisfactory in image quality such as sensitivity at the initial stage of use of the radiation image conversion panel. It is possible.

Further, since the fluororesin film is provided by lamination instead of coating, the film strength can be increased, and a radiation image conversion panel having excellent durability can be obtained.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A radiation image conversion panel according to the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a radiation image conversion panel showing one embodiment of the present invention. The radiation image conversion panel of the present invention has at least a phosphor layer composed of a stimulable phosphor and a protective film, except for a case where the phosphor layer also has a function as a support. In the radiation image conversion panel described above, a support is provided on the back surface of the phosphor layer opposite to the side on which the protective film is provided, and this will be described as an example. A radiation image conversion panel 10 shown in FIG. 1 has a configuration in which a phosphor layer 1 is laminated on a support 3 and a protective film 2 is laminated on the phosphor layer 1.

The stimulable phosphor is stimulated when irradiated with excitation light.
Although it is a phosphor that emits light, it has a wavelength of 4
With excitation light in the range of 00 nm to 900 nm, 30
Phosphor showing stimulated emission in the wavelength range of 0 nm to 500 nm
It is desirable that The radiation image conversion panel of the present invention
Examples of the stimulable phosphor used include U.S. Pat.
859,527: SrS: Ce, Sm, S
rS: Eu, Sm, ThO₂: Er and La₂O₂
S: Eu, Sm, Zn described in JP-A-55-12142.
S: Cu, Pb, BaO.xAl₂O₃: Eu (just
0.8 ≦ x ≦ 10), and M^IIOxSiO₂:
A (however, M^IIIs Mg, Ca, Sr, Zn, Cd
Or Ba, and A is Ce, Tb, Eu, Tm, Pb,
Tl, Bi or Mn, and x is 0.5 ≦ x ≦
2.5), described in JP-A-55-12143.
(Ba_1-xy, Mg_x, Ca_y) FX: aEu²⁺
(Where X is at least one of Cl and Br)
And x and y are 0 <x + y ≦ 0.6 and xy ≠
0 and a is 10^-6≦ a ≦ 5 × 10^-2),
LnOX: xA described in JP-A-55-12144 (only
And Ln is at least one of La, Y, Gd, and Lu.
X is at least one of Cl and Br
A is at least one of Ce and Tb,
X is 0 <x <0.1).
No. 145 (Ba)_1-x, M²⁺ _x) FX: yA
(However, M²⁺Represents Mg, Ca, Sr, Zn, and C
at least one of d, X is Cl, Br and I
At least one of them, A is Eu, Tb, Ce, Tm,
Dy, Pr, Ho, Nd, Yb, and Er
At least one, and x is 0 ≦ x ≦ 0.6, y is 0
.Ltoreq.y.ltoreq.0.2).
M described^IIFX xA: yLn (where M ^IIIs B
a, Ca, Sr, Mg, Zn, and a small amount of Cd
At least one kind, A is BeO, MgO, CaO, SrO, B
aO, ZnO, Al₂O₃, Y₂O₃, La₂O₃, I
n₂O₃, SiO₂, TiO₂, ZrO₂, GeO₂,
SnO₂, Nb₂O₅, Ta₂O₅, And ThO₂of
At least one of them, Ln is Eu, Tb, Ce, T
m, Dy, Pr, Ho, Nd, Yb, Er, Sm, and
X is Cl, Br, and at least one of Gd and Gd.
X and y are at least one of
5 × 10 each^-5≦ x ≦ 0.5 and 0 <y ≦ 0.2
JP-A-56-11)
No. 6777 (Ba)_1-x, M^II _x) F₂ ・
aBaX₂: YEu, zA (where M^IIIs Belliriu
, Magnesium, calcium, strontium,
X is a salt, at least one of lead and cadmium
At least one of nitrogen, bromine and iodine, A is
At least one of zirconium and scandium
A, x, y, and z are each 0.5 ≦ a
≦ 1.25, 0 ≦ x ≦ 1, 10^-6≦ y ≦ 2 × 1
0^-1, And 0 <z ≦ 10^-2Is the composition formula
The phosphor (B) described in JP-A-57-23673 is disclosed.
a_1-x, M^II _x) F₂ ・ ABaX ₂: YEu, z
B (however, M^IIIs beryllium, magnesium, cal
Of Cium, Strontium, Zinc and Cadmium
X is chlorine, bromine, and iodine
A, x, y, and z are:
0.5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1, 10^-6
≦ y ≦ 2 × 10^-1, And 0 <z ≦ 2 × 10^-1In
Phosphor) represented by the composition formula of JP-A-57-236.
No. 75 (Ba)_1-x, M^II _x) F₂ ・ ABa
X ₂: YEu, zA (where M^IIIs beryllium, ma
Gnesium, calcium, strontium, zinc and
At least one of cadmium, X is chlorine, bromine,
And at least one of iodine and A is arsenic and
At least one of silicon, a, x, y, and
And z are respectively 0.5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1,
10^-6≦ y ≦ 2 × 10^-1, And 0 <z ≦ 5 × 10
^-1Phosphor represented by the composition formula:
-69281^IIIOX: xCe (just
Then M^IIIAre Pr, Nd, Pm, Sm, Eu, Tb,
Group consisting of Dy, Ho, Er, Tm, Yb, and Bi
At least one trivalent metal selected from the group consisting of
l and / or Br
And x is 0 <x <0.1).
Phosphor described in JP-A-58-206678.
_1-xM_{x / 2}L_{x / 2} FX: yEu²⁺(However,
M is selected from the group consisting of Li, Na, K, Rb and Cs.
L represents at least one alkali metal;
Sc, Y, La, Ce, Pr, Nd, Pm, Sm, G
d, Tb, Dy, Ho, Er, Tm, Yb, Lu, A
1, Ga, In, and Tl.
Represents at least one trivalent metal; X is Cl, Br,
At least one halo selected from the group consisting of
And x represents 10^-2≦ x ≦ 0.5, y
Satisfies 0 <y ≦ 0.1).
BaFX.x described in JP-A-59-27980
A: yEu²⁺(Where X is Cl, Br, and I
At least one halogen selected from the group consisting of
A is a calcined product of a tetrafluoroborate compound;
And x is 10^-6≦ x ≦ 0.1, y is 0 <y ≦ 0.
A phosphor represented by the composition formula:
BaFX.xA: yEu described in No. 47289²⁺(T
X is selected from the group consisting of Cl, Br and I
Is at least one halogen;
Fluorosilicic acid, hexafluorotitanic acid and hexafu
From the salts of monovalent or divalent metals of fluorodisilconic acid
At least one selected from the group consisting of hexafluoro compounds
And x is 10^-6≤x
≦ 0.1, y is 0 <y ≦ 0.1)
Phosphor described in JP-A-59-56479.
FX xNaX ': aEu²⁺(However, X and X '
Is at least one of Cl, Br and I, respectively.
X and a are each 0 <x ≦ 2, and
0 <a ≦ 0.2), a phosphor represented by a composition formula:
M described in JP-A-59-56480^IIFX xNa
X ': yEu²⁺: ZA (where M^IIIs Ba, S
at least one selected from the group consisting of r and Ca
X and X 'are each
At least selected from the group consisting of Cl, Br, and I
Are also a kind of halogen; A is V, Cr, Mn, F
at least one transition selected from e, Co, and Ni
And x is 0 <x ≦ 2, y is 0 <y ≦
0.2 and z is 0 <z ≦ 10^-2Is the composition formula
Phosphors described in JP-A-59-75200
M^IIFX ・ aM^IX'.bM '^IIX " ₂・ CM
^III X "'₃ XA: yEu²⁺(However, M^IIIs
At least one selected from the group consisting of Ba, Sr, and Ca
Are a kind of alkaline earth metal; ^I Is Li, N
a, K, Rb, and a small number selected from the group consisting of Cs
At least a kind of alkali metal; M '^IIAre Be and
At least one type of divalent gold selected from the group consisting of
Genus; M^III Are Al, Ga, In, and Tl
At least one trivalent metal selected from the group consisting of
A is a metal oxide; X is Cl, Br, and I
At least one halogen selected from the group consisting of
X ', X "and X"' represent F, Cl, Br, and
At least one halogen selected from the group consisting of I
And a is 0 ≦ a ≦ 2, b is 0 ≦ b ≦ 1
0^-2, C is 0 ≦ c ≦ 10^-2And a + b + c ≧ 10
^-6X is 0 <x ≦ 0.5, y is 0 <y ≦ 0.2
A phosphor represented by the composition formula:
M described in No. 4381^IIX₂・ AM^IIX '₂: XEu
²⁺(However, M^IIConsists of Ba, Sr and Ca
At least one alkaline earth metal selected from the group
X and X 'are from the group consisting of Cl, Br and I
At least one selected halogen and X ≠ X ’
And a is 0.1 ≦ a ≦ 10.0, x is 0 <x ≦
Stimulable phosphor represented by the following composition formula:
M described in Kaisho 60-101173^IIFX ・ aM^I 
X ': xEu²⁺(However, M^IIAre Ba, Sr and
At least one alkali selected from the group consisting of Ca
Earth metal; M^I Is a group consisting of Rb and Cs
X is at least one alkali metal selected;
At least selected from the group consisting of Cl, Br and I
X 'is F, Cl, Br and I
At least one halogen selected from the group consisting of
And a and x are 0 ≦ a ≦ 4.0 and
And 0 <x ≦ 0.2).
Phosphor, M described in JP-A-62-25189^I 
X: xBi (where MI is a group consisting of Rb and Cs)
At least one alkali metal selected from the group consisting of: X
Is at least selected from the group consisting of Cl, Br and I
Is also a kind of halogen; and x is 0 <x ≦ 0.2
Stimulable fluorescence represented by the composition formula
LnOX: xC described in JP-A-2-229882
e (where Ln is La, Y, Gd, and Lu)
X is at least one of Cl, Br and I
At least one, x satisfies 0 <x ≦ 0.2, and Ln and X
The atomic ratio is 0.500 <X / Ln ≦ 0.998.
And the maximum wavelength λ of the stimulable excitation spectrum is 550 n
Cerium-activated rare earth represented by m <λ <900 nm)
Oxyhalide phosphors, etc.
You.

Note that the above Japanese Patent Application Laid-Open No. 60-84381 describes
M listed^IIX₂・ AM^IIX '₂: XEu²⁺Photostimulable firefly
The following additives are added to the light body.^IIX₂・ AM
^IIX '₂May be contained in the following proportions per mole
No. BM described in JP-A-60-166379^IX "
(However, M^I Is selected from the group consisting of Rb and Cs
X "is F,
At least selected from the group consisting of Cl, Br and I
A kind of halogen, and b is 0 <b ≦ 10.0
BKX "described in JP-A-60-221483.
・ CMgX "'₂・ DM^III X ""₃(However, M
^III Is a group consisting of Sc, Y, La, Gd and Lu
At least one trivalent metal selected, X ",
X "'and X" "are both from F, Cl, Br and I
At least one halogen selected from the group consisting of
And b, c and d are respectively 0 ≦ b ≦ 2.0, 0
≦ c ≦ 2.0, 0 ≦ d ≦ 2.0, and 2 × 10
^-5.Ltoreq.b + c + d); JP-A-60-228592.
YB (where y is 2 × 10^-4≦ y ≦ 2 ×
10^{− 1}Described in JP-A-60-228593.
BA (where A is SiO₂And P₂O₅Consists of
At least one oxide selected from the group; and
b is 10^-4≦ b ≦ 2 × 10^-1JP-A-61-61
BSiO described in JP-A-120883 (where b is 0 <
b ≦ 3 × 10^-2And JP-A-61-120885.
BSnX "₂ (However, X "is F, Cl,
At least one member selected from the group consisting of Br and I
Halogen and b is 0 <b ≦ 10^-3In
BCsX "described in JP-A-61-235486.
・ CSnX "' ₂ (However, X "and X" 'are each
At least one selected from the group consisting of F, Cl, Br and I
Are a kind of halogen, and b and c are
0 <b ≦ 10.0 and 10 respectively^-6≦ c ≦ 2 × 10
^-2And JP-A-61-235487.
BCsX "・ yLn³⁺(However, X "
At least one selected from the group consisting of F, Cl, Br and I
Ln is Sc, Y, Ce, P
r, Nd, Sm, Gd, Tb, Dy, Ho, Er, T
at least one selected from the group consisting of m, Yb and Lu
Is a kind of rare earth element, and b and y are each
0 <b ≦ 10.0 and 10^-6≦ y ≦ 1.8 × 1
0^-1Is).

Among the above stimulable phosphors, a divalent europium-activated alkaline earth metal halide-based phosphor and a cerium-activated rare earth oxyhalide phosphor are particularly preferred because they exhibit high-luminance stimulable emission. However, the stimulable phosphor used in the present invention is not limited to the above-described phosphors, and any phosphor can be used as long as it exhibits stimulable emission when irradiated with radiation and then irradiated with excitation light. There may be.

The stimulable phosphor layer of the radiation image storage panel of the present invention is not only composed of a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state, but also containing no binder. It may be composed of only a stimulable phosphor aggregate or a phosphor layer in which a polymer substance is impregnated in a gap between the stimulable phosphor aggregates.

Here, a method for producing a phosphor layer will be described by taking as an example a case where the phosphor layer comprises a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state.

The phosphor layer can be formed on a support by the following known method. First, a stimulable phosphor and a binder are added to a solvent, and the mixture is sufficiently mixed with a disperser such as a dissolver to prepare a coating solution in which the stimulable phosphor is uniformly dispersed in a binder solution. . The mixing ratio between the binder and the stimulable phosphor in the coating solution varies depending on the characteristics of the intended radiation image conversion panel, the type of the phosphor, etc.
Generally, the mixing ratio between the binder and the phosphor is from 1: 1 to 1:
The ratio is selected from the range of 100 (weight ratio), and particularly preferably from the range of 1: 8 to 1:40 (weight ratio). The coating solution containing the phosphor and the binder prepared as described above is then uniformly applied to the surface of the support to form a coating film. This coating operation is performed by a normal coating means,
For example, it can be carried out by using an extrusion coater, a slide coater, a doctor blade, a roll coater, a knife coater or the like.

The support can be arbitrarily selected from materials known as supports for conventional radiation image conversion panels. In a known radiation image conversion panel, a phosphor layer is provided to enhance the bond between the support and the phosphor layer or to improve the sensitivity or image quality (sharpness, granularity) of the radiation image conversion panel. A polymer material such as gelatin is applied to the surface of the support on the side to provide an adhesion-imparting layer, or a light-reflective layer made of a light-reflective material such as gadolinium oxide, or a light-absorbing material such as carbon black It is known to provide an absorption layer or the like. The support used in the present invention can also be provided with these various layers, and the configuration thereof can be arbitrarily selected depending on the desired purpose and application of the radiation image storage panel.

As described in JP-A-58-200200, the surface of the support on the side of the phosphor layer (the surface of the support on the side of the phosphor layer) is used for the purpose of improving the sharpness of the obtained image. In the case where an adhesiveness-imparting layer, a light-reflecting layer, a light-absorbing layer, or the like is provided on the surface, the surface thereof may be finely uneven by embossing or the like. After forming a coating on the support as described above, the coating is dried to complete the formation of the stimulable phosphor layer on the support.
The thickness of the phosphor layer depends on the characteristics of the intended radiation image conversion panel, the kind of the phosphor, the mixing ratio of the binder to the phosphor, and the like, but is usually 20 μm to 1 mm.
More preferably, it is 0 to 500 μm. The stimulable phosphor layer does not necessarily need to be formed by directly applying a coating solution on the support as described above. For example, a separate sheet such as a glass plate, a metal plate, or a plastic sheet may be used. After forming a phosphor layer by applying a coating solution on top and drying, pressing this onto a support, or bonding the support and the phosphor layer using an adhesive or the like Good.

Next, a fluororesin film for a protective film, which is a characteristic feature of the radiation image storage panel of the present invention, will be described. Fluororesin film, as already described, means a film obtained by copolymerizing a fluorine-based monomer such as ethylene tetrafluoride, ethylene trifluoride, or vinyl fluoride with a monomer containing or not containing fluorine,
Specifically, for example, a tetrafluoroethylene / hexafluoropropylene copolymer (FEP, weight ratio: 10 to 7)
0 / 90-30), tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride copolymer (weight ratio: 30-70 / 10-50 / 10-50), tetrafluoroethylene / perfluoroalkyl vinyl ether (PFA, weight Ratio: 10-90 / 90-10), polychlorotrifluoroethylene (PCTFE), ethylene /
Tetrafluoroethylene / third component copolymer (ETFE
System copolymer, weight ratio: 40 to 55/40 to 55/5 to 2
0), ethylene / chlorotrifluoroethylene copolymer (ECTFE, weight ratio: 40-60 / 60-40), fluoroethylene / hydrocarbon vinyl ether copolymer (FEVE, weight ratio: 30-90 / 70-10) ), Polyvinyl fluoride (PVF) and the like. The molecular weight MW of these resins is preferably 10,000 to 1,000,000, more preferably about 50,000 to 600,000. These film resins include Mitsui and
Teflon of DuPont Fluorochemicals Co., Ltd., Tefzel, TeflonAF, Tedlar of DuPont, and Neoflon FEP and Neoflon ETF of Daikin Industries, Ltd.
E, NEOFLON CTFE, NEOFLON VDF, Asahi Glass
Aflon, Aflon FEP, Cytop, Sumitomo 3M Co., Ltd.'s Hostaflon TFA, Hostaflon ET,
Dionin and the like are preferred. The thickness of these fluororesin films is 10 μm or less, preferably 6 μm or less, and more preferably 4 μm or less.

The fluororesin film is usually laminated on the stimulable phosphor layer by a so-called laminating process in which the fluororesin film is bonded by using an adhesive used for laminating the films or thermocompression bonding. Lamination can be performed by, for example, a laminating roll.

The protective film of the radiation image storage panel of the present invention may contain various organic / inorganic fine powders to prevent contamination. The size of the fine powder is preferably about 10 nm to 1 μm, particularly preferably about 20 nm to 0.5 μm. As fine powder, alumina sol, alumina fine powder,
Silica sol, silica fine powder, calcium carbonate fine powder, melamine resin particles, benzoguanamine resin particles, silicone resin particles, fluororesin particles, cured acrylic resin powder,
Polyester resin powder and the like are preferred. Examples will be described below.

(Example 1) First, a phosphor layer was prepared.
As a coating solution for forming a phosphor sheet, a tetrahedral phosphor (BaFBr _0.85 I _0.15 : Eu ²⁺ ) 1000 is used.
g, a binder (polyurethane elastomer; Dainippon Ink and Chemicals, Inc., Pandex T-5265H (solid)) dissolved in methyl ethyl ketone (MEK) to a solid content concentration of 13 wt%, 246 g, and a crosslinking agent (Polyisocyanate; Nippon Polyurethane Industry Co., Ltd., Coronate HX (solid content: 100%)) 3 g, yellowing inhibitor (epoxy resin; Yuka Shell Epoxy Co., Ltd., Epicoat #)
1001 (solid)) was added to 69 g of MEK, and dispersed using a dissolver at 2400 rpm for 2 hours to obtain 3
A coating solution of 0 Ps was used. This coating solution is applied onto a temporary support (a polyethylene terephthalate sheet (thickness: 190 μm) coated with a silicone release agent) using an extrusion coater, dried, and then peeled off from the temporary support to obtain a phosphor sheet (sheet). Thickness: 300 μm, coating width = 300 m
m). This operation was repeated to produce a plurality of phosphor sheets.

Next, a reflection (undercoat) layer was formed. Fine particles of gadolinium oxide (Gd ₂ O ₃ ) (90% by weight of all particles having a particle diameter in the range of 1 to 5 μm) 3
0 parts, as a binder, a soft acrylic resin (Chris Coat
P-1018GS: 20% solution; Dainippon Ink and Chemicals, Inc. 3
0 parts, 3.5 parts of phthalic acid ester, conductive agent: 10 parts of ZnO whisker, 0.4 part of ultramarine blue as a colorant in an appropriate amount of M
In addition to EK, disperse and mix using a propeller mixer,
A coating liquid for forming a reflection (undercoat) layer having a viscosity of 10 PS (20 ° C.) was prepared. Polyethylene terephthalate (support) having a thickness of 300 μm is placed horizontally on a glass plate, and the coating solution for forming an undercoat layer is uniformly applied on the support using a doctor blade, and then the coating film is dried. A reflective layer (layer thickness: 20 μm) was formed on the support.

The phosphor sheet prepared above was placed on the reflective layer formed on the support, and compression was performed. Compression is performed using a calendar roll at 500 kgw / cm.
² pressure, upper roll temperature 90 ° C, lower roll temperature 7
The operation was continuously performed at 5 ° C. and a feed speed of 1.0 m / min. By this compression, the phosphor sheet and the support were completely fused. The thickness of the phosphor layer after fusion is 220μ.
m.

Subsequently, a protective film was formed. Perfluoroalkyl resin (manufactured by Daikin Industries, Ltd .: NEOFLON FEP,
(Light transmittance: about 92%) was stretched to form a 6 μm film, which was then adhered to a 25 μPET temporary support. The surface of the perfluoroalkyl resin film was subjected to corona discharge treatment to provide an adhesive layer (adhesive application weight 2 g / m ² ). This FEP polymer film is laminated using a laminating roll,
After bonding to the phosphor layer via an adhesive layer, the PET temporary support was peeled off and an embossed pattern was formed. As a result, a protective film having a surface roughness (Ra = 0.2 μm) was obtained, and the panel was completed.

Example 2 A panel was completed in the same manner as in Example 1 except that the thickness of the film used for the protective film of Example 1 was changed to 3 μm.

Comparative Example 1 A panel was completed in the same manner as in Example 1 except that a 6 μm-thick PET film was used in place of the FEP polymer film used in Example 1.

(Evaluation Experiment) Luminous intensity and sharpness Luminous intensity was measured by applying a tube voltage of 80 to each radiation image conversion panel.
After irradiating with kVp X-rays, the panel was excited with He-Ne laser light (wavelength: 632.8 nm), the amount of stimulated emission of each panel was measured, and the relative value with the measured value of Comparative Example 1 being 100%. Was evaluated.

The sharpness (MTF) is obtained by measuring the sharpness (resolution) of each panel at a spatial frequency of 2 cycles / mm using a test chart for X-ray MTF measurement in the same manner as in the measurement of emission intensity. Was evaluated.

2. Antifouling property The antifouling property of each protective film surface of the radiation image conversion panel was measured by the following method. First, the radiation image conversion panel was cut into a rectangle of 25.2 cm × 30.3 cm to prepare a measurement sample. Next, the panel was moved with a rubber roller used in a radiation image converter to 10,000
After reciprocating and rubbing the panel and rubber roller repeatedly,
The protective film surface of the sample was visually observed and evaluated. The evaluation was performed based on the following three levels.

A: Almost no dirt adhered B: Dirt slightly adhered, but not practically problematic C: Dirt adhered much The results are shown in Table 1.

[0041]

[Table 1] As is clear from Table 1, the protective film of the radiation image storage panel of the present invention has excellent antifouling property and has a film thickness of 1 μm to 10 μm.
m, wavelength 400 nm to 900 of fluororesin film
90% light transmittance for stimulated emission light and excitation light
To 100%, it was possible to obtain a radiation image conversion panel having high emission intensity and sharpness and good image quality.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a radiation image conversion panel according to a first embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 stimulable phosphor layer 2 protective film 3 support 10 radiation image conversion panel

Claims (3)

[Claims] 1. A radiation image conversion panel having at least a phosphor layer made of a stimulable phosphor and a protective film laminated on the phosphor layer, wherein the protective film is laminated on the phosphor layer. Is a fluororesin film having a thickness of 1 μm to 10 μm.
A radiation image conversion panel having a light transmittance of 90% to 100% for stimulated emission light and excitation light of 0 nm to 900 nm. 2. The film thickness of the fluororesin film is 1 μm.
The radiation image conversion panel according to claim 1, wherein the thickness of the radiation image conversion panel is in the range of 6 to 6 m. 3. The radiation image conversion panel according to claim 1, wherein the light transmittance is from 92% to 100%.