JP2002116300A - Radiation luminescence panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a radiation luminescence panel having little image nonuniformities, high filling factor and high sensitivity. SOLUTION: When a luminescence layer of a radiation luminescence panel is formed by applying, polymer dispersing agent consisting of copolymer, having a single functional group at a molecule end or comb-shaped copolymer which has a plurality of functional groups in the molecule side chain is contained in luminescence application liquid.

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 in a radiation image conversion method using a stimulable phosphor, and a method for converting transmitted radiation into visible light and / or ultraviolet radiation by the phosphor. The present invention relates to a radiation emitting panel such as an intensifying panel for X-ray photography.

[0002]

2. Description of the Related Art As an alternative to the conventional radiographic method, there is known a radiation image conversion method using a stimulable phosphor as described in, for example, JP-A-55-12145. This method uses a radiation image conversion panel (a stimulable phosphor sheet) containing a stimulable phosphor, and transmits radiation transmitted through a subject or emitted from a subject to the stimulable phosphor of the panel. And then stimulating the stimulable phosphor with electromagnetic waves (excitation light) such as visible light and infrared light in a time-series manner, so that the radiation energy accumulated in the stimulable phosphor is (Stimulated emission light), and the fluorescence is photoelectrically read to obtain an electric signal.
Then, a radiation image of the subject or the subject is reproduced as a visible image based on the obtained electric signal. 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 operation, this radiographic image conversion method uses a 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, an inorganic or organic support and a stimulable phosphor layer provided on the surface thereof. Since the stimulable phosphor of the phosphor layer has a property of exhibiting stimulable emission when irradiated with excitation light after absorbing radiation such as X-rays, the stimulable phosphor is transmitted through the subject or emitted from the subject. Radiation is absorbed by the stimulable phosphor layer of the radiation image conversion panel in proportion to the radiation dose, and a radiation image of a subject or a subject is formed on the panel as a radiation energy accumulation image. 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.

Although the radiation image conversion method is a very advantageous image forming method as described above, the radiation image conversion panel used in this method has the same high sensitivity as the intensifying screen used in the conventional radiography. In addition, it is desired to provide an image having good image quality (sharpness, granularity, etc.).

[0006] The sensitivity of the radiation image conversion panel basically depends on the total stimulable luminescence amount of the stimulable phosphor contained in the panel, and the total luminous amount depends only on the luminous brightness of the phosphor itself. It depends on the phosphor content in the phosphor layer. Since a high content of the phosphor means that the absorption of radiation such as X-rays is large, a higher sensitivity is obtained, and at the same time, the image quality (particularly the granularity) is improved. On the other hand, when the phosphor content in the phosphor layer is constant, the layer thickness can be reduced as the phosphor particles are more densely packed, so that the spread of excitation light due to scattering is reduced. And a relatively high sharpness can be obtained.

[0007] The applicant of the present invention has proposed a radiation image conversion panel having a phosphor layer densely filled with phosphors, in which the porosity of the phosphor layer is reduced by compressing the phosphor layer. An image conversion panel and a method for manufacturing the same have already been filed (see JP-A-59-126299 and JP-A-59-126300).

[0008]

In the above-mentioned radiation image conversion panel, the density of the phosphor in the phosphor layer is higher than that of the conventional radiation image conversion panel and the density unevenness is obtained by compressing the phosphor layer. Was reduced. as a result,
Although this radiation image conversion panel had excellent sharpness, such compression processing sometimes left uneven density of the phosphor, which resulted in uneven emission of the panel and image quality. However, there is a problem that there is a case where is not enough.

In general, the coating liquid for the phosphor layer dissolves the binder resin well at the time of high shearing at the time of dispersion and coating, the viscosity is moderately low, and the shearing force at the time of dispersion becomes heat energy and may be lost. It is preferable that the particles are small and that the aggregates of the phosphor particles can be easily crushed. On the other hand, it is preferable that the particles are so-called thixotropic and have high viscosity and are hard to flow at the time of low shearing during drying after coating.

That is, in order to uniformly disperse the phosphor particles, it is preferable that the viscosity of the coating solution is low.
In order to uniformly fill the phosphor particles after drying and obtain a phosphor coating film having a uniform thickness, it is preferable that the coating solution has a high viscosity, and contradictory properties are required for the coating solution, While the dispersion of the phosphor particles is good,
It is not easy to obtain a phosphor layer with low noise and less unevenness.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a radiation-emitting panel which has less image unevenness, a high filling rate of a phosphor, and a good sensitivity.

It is also disclosed in JP-A-10-246800 that a binder having a hydrophilic polar group is contained in the binder of the phosphor layer of the radiation intensifying screen and the radiation image conversion panel. However, the first object of the invention described herein is to improve the sharpness, for which a hydrophilic functional group is randomly introduced into a binder or a part of the binder, and the present invention As described above, the use of a polymer dispersant comprising a copolymer having a functional group at the molecular end or a comb-type copolymer having a plurality of functional groups at the molecular side chains has not been shown, and the present invention is not described at all. No suggestion.

[0013]

According to the present invention, there is provided a radiation emitting panel comprising at least a support and a phosphor layer provided on the support, wherein the phosphor layer comprises a phosphor, A polymer dispersant comprising a copolymer having one functional group at a molecular terminal or a comb-shaped copolymer having a plurality of functional groups in a molecular side chain.

A radiation-emitting panel is a radiation image conversion panel containing a stimulable phosphor or an X-ray for converting transmitted radiation into visible light and / or ultraviolet radiation using a non-stimulable phosphor. This is a wide concept including photographic intensifying panels.

The functional group is preferably a basic type functional group. The amount of the polymer dispersant added is preferably 0.001% by weight to 1% by weight based on the phosphor. The phosphor may be a stimulable phosphor.

[0016]

According to the radiation-emitting panel of the present invention, the phosphor layer comprises a phosphor and a comb-shaped copolymer having one functional group at a molecular end or a plurality of functional groups at a molecular side chain. Since it contains a polymer dispersant consisting of a polymer, the dispersibility of the phosphor particles is improved, and the viscosity of the phosphor layer coating solution is improved, and the coating solution is rapidly dried and fluidized in the drying zone. Thus, a uniform and smooth phosphor coating film can be obtained, and a phosphor filling rate is high, and a good radiation sensitive panel with less image unevenness and sensitivity can be obtained.

That is, the phosphor layer has a coating thickness of about
Due to the thickness of 500 μm, convection due to transport vibration and solvent evaporation occurs in the coating film until the coating film dries, but by including a polymer dispersant in the phosphor layer coating solution,
It is considered that the viscosity of the coating liquid can be increased and the flow of the coating liquid can be prevented, so that a dried coating film having a uniform filling degree and thickness can be obtained. Moreover, while the polymer dispersant as described above is thickened, it dissolves the binder resin well, has a moderately low viscosity, easily breaks up the aggregates of the phosphor particles, and reduces the phosphor particles. Since it can be uniformly dispersed, it is possible to obtain a radiation-emitting panel with less image unevenness and a high phosphor filling rate and good sensitivity.

By making the functional group of the polymer dispersant a basic type functional group, the solubility in an organic solvent and a binder contained in the phosphor layer coating solution is improved, and the dispersibility of the phosphor particles is improved. Can be improved.

When the amount of the polymer dispersant added is from 0.001% by weight to 1% by weight based on the phosphor, the above effect can be further enhanced.

It is to be noted that the present invention provides a panel for converting transmitted radiation into visible light and / or ultraviolet radiation using a non-stimulable phosphor, for example, improving the image quality of a phosphor layer such as an intensifying panel for X-ray photography. However, it is extremely useful in a radiation image conversion panel using a stimulable phosphor.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial sectional view of a radiation-emitting panel according to the first embodiment of the present invention.

As shown in FIG. 1, a radiation-emitting panel generally has a structure in which a phosphor layer 1 is laminated on a support 3 and a protective layer 2 is further laminated on the phosphor layer 1. Protective layer 2
Protects the phosphor layer from physical impact and chemical alteration. Hereinafter, based on this radiation-emitting panel,
Each layer will be described.

First, the phosphor of the radiation-emitting panel of the present invention
The case where the phosphor in the layer is a stimulable phosphor will be described.
The stimulable phosphor was irradiated as described above
After that, it is a phosphor that shows stimulated emission when irradiated with excitation light
However, from a practical point of view, the excitation wavelength is in the range of 400 to 900 nm.
Fluorescent light that emits photostimulated light in the wavelength range of 300 to 500 nm
Preferably, it is a light body. Radiation image conversion panel of the present invention
Examples of the stimulable phosphor used in the
BaSO described in 80487_Four: AX and JP-A-48-80
SrSO described in Issue 489_Four: AX phosphor
Li described in JP-A-53-39277_TwoB_FourO₇: Cu, Ag, JP
Li described in No. 54-47883_TwoO ・ (B_TwoO_Two) x: Cu and
Li_TwoO ・ (B_TwoO_Twox: Cu, Ag, in U.S. Pat.No. 3,859,527
Listed SrS: Ce, Sm, SrS: Eu, Sm, ThO_Two: Er, and
And La_TwoO_TwoS: Eu, Sm, Z described in JP-A-55-12142
nS: Cu, Pb, BaOxAl_TwoO_Three: Eu (0.8 ≦ x ≦ 10)
And M^IIOxSiO_Two: A (but M^IIIs Mg, Ca, Sr, Zn,
Cd or Ba, A is Ce, Tb, Eu, Tm, Pb, Tl, Bi
Or Mn, and x is 0.5 ≦ x ≦ 2.5).
No. 12143 (Ba_1-Xy, Mg_X, Ca_y) FX: aEu
²⁺(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^-2And JP-A-55-1214
LnOX: xA described in No. 4 (where Ln is La, Y, G
at least one of d and Lu; X is Cl and Br
At least one of them, A is at least one of Ce and Tb
And x is 0 <x <0.1).
No. 55-12145 (Ba_1-X, M²⁺ _X) FX: yA (ta
But M²⁺Is the lesser of Mg, Ca, Sr, Zn, and Cd
X is at least one of Cl, Br and I
Species, A is Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb and Er
X is 0 ≦ x ≦ 0.6, y
Is 0 ≦ y ≦ 0.2), and described in JP-A-55-843897.
BaFX: a phosphor represented by xCe · yA M described in JP-A-55-160078^IIFX xA: yLn (ta
But M^IIIs the smallest of Ba, Ca, Sr, Mg, Zn and Cd.
At least one kind, A is BeO, MgO, CaO, SrO, BaO, ZnO, Al
_TwoO_Three, Y_TwoO_Three, La_TwoO_Three, In_TwoO_Three, SiO_Two, TiO_Two, ZrO_Two, GeO_Two, S
nO_Two, Nb_TwoO_Five, Ta_TwoO_FiveAnd ThO_TwoAt least one of
Species, Ln is Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Sm
X is Cl, Br and I
Where x and y are each 5
× 10^-Five≤ x ≤ 0.5, and 0 <y ≤ 0.2)
Phosphors represented by JP-A-56-116777.
(Ba_1-X, M^II _X) F_Two・ ABaX_Two: yEu, zA (where M^IIIs berili
, Magnesium, calcium, strontium, sub
At least one of lead and cadmium, X is a salt
At least one of iodine, bromine and iodine;
At least one of ruconium and scandium
Wherein a, x, y, and z are each 0.5 ≦ a ≦ 1.
25, 0 ≦ x ≦ 1, 10^-6≦ y ≦ 2 × 10^-1, And 0 <z ≦ 1
0^-2A phosphor represented by the composition formula:
No. 673 (Ba_1-X, M^II _X) F_Two・ ABaX_Two: yEu, zB
(However, M ^IIIs beryllium, magnesium, and calcium
Medium, strontium, zinc and cadmium
X is at least one of chlorine, bromine and iodine.
A, x, y, and z are each
0.5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1, 10^-6≦ y ≦ 2 × 10^-1, And
And 0 <z ≦ 10^-2Is a phosphor represented by the composition formula:
JP-A-57-23675 (Ba_1-X, M^II _X) F_Two・ AB
aX_Two: yEu, zA (where M^IIIs beryllium, magnesium
Calcium, strontium, zinc and cadmium
X is chlorine, bromine and iodine
At least one of the elements, A is one of arsenic and silicon
A, x, y, and z are
0.5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1, 10 respectively^-6≦ y ≦ 2 × 10^-1,
And 0 <z ≦ 5 × 10^-1Is represented by the composition formula
Phosphor, M described in JP-A-58-69281^IIIOX: xC
e (but M^IIIAre Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, E
at least one selected from the group consisting of r, Tm, Yb and Bi
X is one of Cl and Br
X is 0 <x <0.1
Phosphor) represented by the composition formula of JP-A-58-206678.
Ba as described in_1-XM_{X / 2}L_{X / 2}FX: yEu²⁺(However, M
Is a small number selected from the group consisting of Li, Na, K, Rb and Cs.
L represents Sc, Y, L
a, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Y
b, Lu, Al, Ga, In and Tl
Represents at least one trivalent metal; X is Cl, Br and
At least one halogen selected from the group consisting of
Represents; and x is 10^-2≦ x ≦ 0.5, y is 0 <y ≦ 0.1
A phosphor represented by the composition formula of JP-A-59-27980
BaFX xA: yEu²⁺(However, X is Cl, Br and
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 ≦ 0.1
JP-A-59-38278.
XM listed in the issue_Three(PO_Four)_Two・ NX_Two: yA, M_Three(PO_Four)_Two: yA
And nReX_Three・ MAX ′_Two: xEu, nReX_Three・ MAX ′_Two: xEu, ySm, M^IX
・ AM^IIX ′_Two・ BM^IIIX ″_Three: a phosphor represented by cA, JP-A-59
BaFX xA: yEu described in -47289²⁺(However, X
Is at least selected from the group consisting of Cl, Br and I
A is a halogen; A is hexafluorosilicic acid,
Xafluorotitanic acid and hexafluorozirconium
Hexafluoro which consists of monovalent or divalent metal salts of humic acid
B) calcination of at least one compound selected from the group of compounds
Thing; and x is 10^-6≦ x ≦ 0.1, y is 0 <y ≦
0.1) is disclosed in JP-A-59-5.
BaFX xNaX ': aEu described in No. 6479²⁺(However, X
And X 'are each a small number of Cl, Br and I
X and a are each 0 <x ≦ 2,
And 0 <a ≦ 0.2).
, M described in JP-A-59-56480^IIFX ・ xNaX ′:
yEu²⁺: zA (where M^IIIs the group consisting of Ba, Sr and Ca
At least one alkaline earth metal selected from
X and X 'each consist of Cl, Br and I
At least one halogen selected from the group; A is
At least one selected from V, Cr, Mn, Fe, Co and Ni
Species are transition metals; and x is 0 <x ≦ 2, y is 0
<Y ≦ 0.2, and z is 0 <z ≦ 10^-2Is the composition formula
Phosphor described in JP-A-59-75200.
M^IIFX ・ aM^IX ′ ・ bM ′^IIX ″_Two·cm^IIIX_Three・ XA: yEu²⁺(T
But M^IIIs a member selected from the group consisting of Ba, Sr and Ca
At least a kind of alkaline earth metal; M^IIs Li, N
at least selected from the group consisting of a, K, Rb and Cs
A kind of alkali metal; M '^IIConsists of Be and Mg
At least one divalent metal selected from the group; M^III
Is at least selected from the group consisting of Al, Ga, In and Tl
Is also a trivalent metal; A is a metal oxide; X is C
at least one selected from the group consisting of l, Br and I
X ', X "and X are F, Cl, Br and
At least one halogen selected from the group consisting of
And a is 0 ≦ a ≦ 2 and b is 0 ≦ b ≦ 1
0^-2, C is 0 ≦ c ≦ 10^-2, And a + b + c ≧ 10^-6And x
Is 0 <x ≦ 0.5 and y is 0 <y ≦ 0.2)
Phosphor represented, described in JP-A-60-84381
 M^IIX_Two・ AM^IIX ′_Two: xEu²⁺(However, M^IIIs Ba, Sr and
 At least one alkali selected from the group consisting of Ca
Is an earth metal; X and X 'consist of Cl, Br and I
At least one halogen selected from the group
X ≠ X ′; and a is 0.1 ≦ a ≦ 10.0, x is 0 <
x ≦ 0.2), a stimulable phosphor represented by a composition formula:
M described in JP-A-60-101173^IIFX ・ aM^IX ′: xE
u²⁺(However, M^{II Is}Selected from the group consisting of Ba, Sr and Ca
At least one alkaline earth metal; M^I
Is at least one member selected from the group consisting of Rb and Cs
X is an alkali metal; X is from the group consisting of Cl, Br and I
X 'is at least one halogen selected; X' is F, C
at least one selected from the group consisting of l, Br and I
And a and x are each 0 ≦ a
≦ 4.0 and 0 <x ≦ 0.2)
Stimulable phosphor, M described in JP-A-62-25189
^IX: xBi (where M^IIs selected from the group consisting of Rb and Cs
At least one alkali metal; X is Cl,
At least one member selected from the group consisting of Br and I
X is a number in the range 0 <x ≦ 0.2
Stimulable phosphor represented by the composition formula
be able to.

Further, the JP 60-84381 No. M ^II X ₂ · aM ^II X described in the _'2: xEu ²⁺ stimulable phosphor, additives such as shown below M ^II X ₂ · aM ^II X ′ ₂ may be contained in the following ratio per 1 mol.

BM described in JP-A-60-166379
^IX "(M^IIs selected from the group consisting of Rb and Cs
X "is at least one alkali metal, and X" is F, Cl, B
at least one member selected from the group consisting of r and I
And b is 0 <b ≦ 10.0);
BKX ″ and cMgX described in Sho 60-221483_Two・ DM
^IIIX ′_Three(However, M^IIIIs Sc, Y, La, Gd and Lu
At least one trivalent metal selected from the group consisting of
X ”, X and X ′ are all F, Cl, Br and I
At least one halogen selected from the group consisting of
And b, c and d are each 0 ≦ b ≦ 2.0,
0 ≦ c ≦ 2.0, 0 ≦ d ≦ 2.0, and 2 × 10^-Five≤b + c
+ d); yB described in JP-A-60-228592
(However, y is 2 × 10^-Four≦ y ≦ 2 × 10^-1JP-A-60
BA (where A is SiO _TwoAnd
And P_TwoO_FiveAt least one oxide selected from the group consisting of
And b is 10^-Four≦ b ≦ 2 × 10^-1);
BSiO described in No. 61-120883 (where b is 0 <b
≦ 3 × 10^-2Is described in JP-A-61-120885.
BSnX ″_Two(However, X ″ is composed of F, Cl, Br and I.
At least one halogen selected from the group consisting of
And b is 0 <b ≦ 10^-3Described in JP-A-61-235486.
BCsX ″ and cSnX listed_Two(However, X ″ and X are
A small number selected from the group consisting of F, Cl, Br and I, respectively.
At least a kind of halogen, and b and c are
0 <b ≦ 10.0 and 10 respectively^-6≦ c ≦ 2 × 10^-2In
BCs described in JP-A-61-235487
X ″ ・ yLn³⁺(However, X ″ consists of F, Cl, Br and I
Ln is at least one halogen selected from the group
Sc, Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb
At least one rare earth selected from the group consisting of
And b and y are each 0 <b ≦
10.0 and 10 ^-6≦ y ≦ 1.8 × 10^-1Is).

Among the stimulable phosphors described above, a divalent europium-activated alkaline earth metal halide-based phosphor and a cerium-activated rare earth oxyhalide-based phosphor are particularly preferable 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 radiation-emitting panel of the present invention is
Transmissive radiation with visible light and
And / or panels for converting to ultraviolet radiation, for example
The phosphor used for radiographic intensifying screens
As a tungstate-based phosphor (CaWO_Four, MgW
O_Four, CaWO_Four: Pb), terbium-activated rare earth oxysulfide
Phosphor (Y_TwoO_TwoS: Tb, Gd_TwoO_TwoS: Tb, La_TwoO_TwoS: Tb, (Y, Gd)_TwoO
_TwoS: Tb, (Y, Gd) O_TwoS: Tb, Tm etc.), Terbium activated rare earth
Phosphate phosphors (YPO_Four: Tb, GdPO_Four: Tb, LaPO_Four: Tb
Terbium-activated rare earth oxyhalide-based fireflies
Optical body (LaOBr: Tb, LaOBr: Tb, Tm, LaOCl: Tb, LaOCl: Tb, T
m, LaOCl: Tb, Tm, LaOBr: Tb, GdOBr: Tb, GdOCl: Tb
Thulium-activated rare earth oxyhalide phosphor
(LaOBr: Tm, LaOCl: Tm, etc.), barium sulfate based phosphor
(BaSO_Four: Pb 、 BaSO_Four:EU²⁺, (Ba, Sr) SO_Four:EU²⁺Such),
Bivalent europium activated alkaline earth metal phosphate-based fireflies
Light body (Ba_Three(PO_Four)_Two:EU²⁺, Ba_Three(PO_Four)_Two:EU²⁺Etc.)
Europium activated alkaline earth metal fluoride halides
Phosphor (BaFCl: EU²⁺, BaFBr: Eu²⁺, BaFCl: EU²⁺, Tb, Ba
FBr: Eu²⁺, Tb, BaF_Two・ BaCl_Two・ KCl: Eu²⁺, (Ba ・ Mg) F_Two・ BaCl
_Two・ KCl: Eu ²⁺Etc.), iodide-based phosphors (CsI: Na, CsI: T
l, NaI, KI: Tl), sulfide-based phosphors (ZnS: Ag, (Zn, C
d) S: Ag, (Zn, Cd) S: Cu, (Zn, Cd) S: Cu, Al, etc.), phosphoric acid
Hafnium-based phosphor (HfP_TwoO₇: Cu etc.), tantalate
Based phosphor (YTaO_Four, YTaO_Four: Tm, YTaO_Four: Nb 、 (Y, Sr) TaO
_4-x: Nb, LuTaO_Four, LuTaO_Four: Nb 、 (Lu, Sr) TaO_4-x: Nb, Gd
TaO_Four: Tm, Gd_TwoO_Three・ Ta_TwoO_Five・ B_TwoO_Three: Tb)
Can be However, the phosphor used in the present invention is
It is not limited to these, but can be
Use any phosphor that emits light in the visible or near ultraviolet region.
Can be

Hereinafter, a radiation image conversion panel using a stimulable phosphor will be described. In the case of a sensitizing panel for X-ray photography, it can be manufactured in a similar manner using known materials and methods.

As the binder used in the present invention, a thermoplastic elastomer which has elasticity at ordinary temperature and becomes fluid when heated is suitably used. Examples of the thermoplastic elastomer include polystyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, ethylene vinyl acetate, polyvinyl chloride, natural rubber, fluorine rubber, polyisoprene, chlorinated polyethylene, styrene-butadiene rubber, and silicone rubber. I can give it.

Of the above-mentioned thermoplastic elastomers, those having a softening temperature or melting point of 30 ° C. to 300 ° C. are generally used, and those having a softening temperature of 30 ° C. to 200 ° C. are preferably used. It is more preferable to use

The above binder is sufficiently mixed with a stimulable phosphor and a solvent to prepare a coating liquid in which the stimulable phosphor is uniformly dispersed in a binder solution.

Examples of the solution include methanol, ethanol,
lower alcohols such as n-propanol, n-butanol and diacetone alcohol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; esters of lower fatty acids such as methyl acetate, ethyl acetate and butyl acetate with lower alcohols; ethylene Ethers such as glycol monopropyl ether; hydrocarbons such as toluene, xylene and cyclohexane;
And mixtures thereof.

The mixing ratio between the binder and the stimulable phosphor in the coating solution varies depending on the desired characteristics of the radiation image conversion panel, the type of the phosphor, and the like. Is selected from the range of 1: 1 to 1: 100 (weight ratio), and is particularly preferably selected from the range of 1: 8 to 1:40 (weight ratio).

The polymer dispersant contained in the phosphor layer is composed of a copolymer having one functional group at a molecular terminal or a comb copolymer having a plurality of functional groups at a molecular side chain. Here, the comb copolymer is a copolymer having a molecular structure as shown in FIG. 2 (FIG. 2 is a conceptual schematic diagram of the comb copolymer). In FIG. 2, R represents an OH group, an amine group, an amino group,
Represents a basic functional group such as a quaternary ammonium base. Comb copolymers having a plurality of functional groups in the molecular side chains have good or relatively good solubility in organic solvents and binders, are not toxic to the human body and have little harm, It is necessary that the luminous efficiency is not reduced and that the cost is as low as possible. An amine group or an amino group is preferable.

In FIG. 2, the main chain represented by jaggedness, and
The side chain shown in the form of a string is a copolymer or polymer of a vinyl compound, or a macromer or polymer such as a polyester compound. Molecular weight (Mw) about 10,000 to 100
It is preferably 10,000, and particularly preferably about 50,000 to 500,000.

When the polymer dispersant is a copolymer having one functional group at the molecular terminal, the functional group referred to here is also OH group, amine group, amino group, 4th
It is a basic functional group such as a quaternary ammonium base, and more preferably an amine group or an amino group. Preferably, the molecular weight (Mw) is about 2000 to 100,000.

The amount of the polymer dispersant added depends on the phosphor.
It is preferably from 0.0001% to 5% by weight, more preferably from 0.001% to 1% by weight, further preferably from 0.01% to 0.5% by weight.

The polymer dispersant comprising a copolymer having one functional group at the molecular terminal or a comb-type copolymer having a plurality of functional groups in the molecular side chain according to the present invention is Solsperse from Zeneca Corporation. 9000, 13000 series, 17000, 18000, 24000G
R, 24000SC, 28000, 32000 series, and are commercially available under the trade names of 33500, 38500, and may be used. Of these, 24000GR is more preferably used.

The coating solution may contain various additives such as a plasticizer for improving the bonding strength between the binder and the phosphor in the formed phosphor layer.
Examples of plasticizers used for such purposes include phosphate esters such as triphenyl phosphate, tricresyl phosphate and diphenyl phosphate; phthalate esters such as diethyl phthalate and dimethoxyethyl phthalate; ethyl phthalate glycolate Glycolic acid esters such as ruethyl and butylphthalylbutyl glycolate; and polyesters of polyethylene glycol and aliphatic dibasic acid such as polyesters of triethylene glycol and adipic acid, polyesters of diethylene glycol and succinic acid, and the like. be able to.

The coating solution containing the phosphor and the binder prepared as described above is uniformly applied to the surface of the temporary support for forming a sheet to form a coating film of the coating solution. This coating operation can be performed by using ordinary coating means, for example, an extrusion coater, a slide coater, a doctor blade, a roll coater, a knife coater, or the like.

The temporary support is, for example, glass, a metal plate,
Alternatively, it can be arbitrarily selected from various materials used as a support for an intensifying screen (or an intensifying screen) in a conventional radiographic method or a material known as a support for a radiation image conversion panel. Examples of such materials include cellulose acetate, polyethylene terephthalate, polyethylene naphthalate, polyamide,
Polyimide, films of plastic substances such as polycarbonate, aluminum foil, metal sheets such as aluminum alloy foil, ordinary paper, baryta paper, resin coated paper, pigment paper containing pigments such as titanium dioxide,
Examples include paper or sheets sized with polyvinyl alcohol or the like, and plates or sheets of ceramics such as alumina, zirconia, magnesia, and titania.

A coating solution for forming a phosphor layer is applied on a temporary support, dried, and then peeled off from the temporary support to form a phosphor sheet to be a phosphor layer of a radiation image conversion panel. Therefore, it is preferable to apply a release agent on the surface of the temporary support in advance so that the formed phosphor sheet can be easily peeled off from the temporary support.

Next, a support for the radiation image conversion panel is prepared separately from the phosphor sheet formed as described above. This support can be arbitrarily selected from the same materials as the temporary support used when forming the phosphor sheet.

In order to strengthen the bond between the support and the phosphor layer,
Alternatively, in order to improve the sensitivity or image quality (sharpness, granularity) of the radiation image conversion panel, a polymer material such as a polyester copolymer or an acrylic resin copolymer is provided on the surface of the support on which the phosphor layer is provided. It is known to provide an adhesiveness-imparting layer by applying a coating material, or to provide a light-reflective layer made of a light-reflective substance such as titanium dioxide, or a light-absorbing layer made of a light-absorbing substance such as carbon black. Regarding the support used in the present invention,
These various layers can be provided, and their configuration can be arbitrarily selected according to the purpose, use, and the like of the radiation image storage panel.

As described in JP-A-59-200200, 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. When an adhesiveness-imparting layer, a light-reflecting layer, a light-absorbing layer, or the like is provided on the surface, it means the surface), and fine irregularities may be formed on the surface.

The phosphor sheet obtained by dispersion coating is placed on a support and adheres to the support while compressing at a temperature not lower than the softening temperature or melting point of the binder. Since the coating of the phosphor sheet is homogenized by the comb copolymer, by applying a pressure treatment to the phosphor sheet, the filling rate of the phosphor can be further increased, and the phosphor coating is uniformly compressed. be able to.

Examples of the compression apparatus used for the compression processing include generally known apparatuses such as a calender roll and a hot press. For example, the compression treatment using a calender roll is performed by placing a phosphor sheet obtained by dispersion coating on a support and passing the phosphor sheet at a constant speed between rollers heated to a temperature higher than the softening temperature or melting point of the binder. . However, the compression device used in the present invention is not limited to these devices, and may be any device capable of compressing the above-mentioned sheet while heating it. The pressure at the time of compression is preferably 5 MPa or more.

In a normal radiation image conversion panel, as described above, a transparent protective layer for physically and chemically protecting the phosphor layer is provided on the surface of the phosphor layer opposite to the side in contact with the support. A membrane is provided. Such a transparent protective film is preferably provided also for the radiation image conversion panel according to the present invention.

The transparent protective film is made of, for example, a fluororesin copolymer, cellulose derivatives such as cellulose acetate and nitrocellulose; or polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, etc. Can be formed by applying a solution prepared by dissolving the above transparent synthetic resin in an appropriate solvent to the surface of the phosphor layer. Alternatively, a plastic sheet made of polyethylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polyvinylidene chloride, polyamide, and the like; and a protective film forming sheet such as a transparent glass plate are separately formed, and are appropriately bonded to the surface of the phosphor layer. It can also be formed by a method such as bonding using an agent. The thickness of the protective film is preferably in the range of about 0.1 to 20 μm.

Further, for the purpose of improving the sharpness of the obtained image, at least one of the above layers may be provided with a coloring layer which absorbs excitation light but does not absorb stimulated emission light. No. 59-23400).

Hereinafter, the present invention will be described more specifically with reference to examples.

EXAMPLES (Example 1) First, a phosphor sheet was manufactured. BaFBr _0.85 I _0.15 : Eu ²⁺ (particle size 3
1000 parts of μmφ / 7μmφ = 5/5) 236.6 parts of polyurethane resin as binder (purified product of Pandex T-5205, 15% methyl ethyl ketone (MEK) solution, manufactured by Dainippon Ink and Chemicals, Inc.), polyisocyanate as crosslinking agent (Nippon Polyurethane Industry
4.5 parts of Coronate HX (100% solids)) and an epoxy resin (EP1001 manufactured by Yuka Shell Epoxy Co., Ltd.) as a yellowing inhibitor
50% MEK solution) 20.0 parts, ultramarine as a colorant (Daiichi Kasei Kogyo Co., Ltd., SM-1) 0.02 parts, comb copolymer having multiple basic functional groups in the molecular side chain (Zeneca ( Solsperse Co., Ltd.
24000GR) Add 0.5 parts to MEK, disperse by disperser,
A coating solution having a viscosity of 4 Pa · s (20 ° C.) was prepared.

A polyethylene terephthalate coated with a silicone release agent (temporary support, thickness 180 μm)
After coating on top and drying, it was peeled off from the temporary support to form a phosphor sheet (250 μm thickness).

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 of 1 to 5 μm) in 30 parts,
Soft acrylic resin (Chris Coat P-1018G as binder)
S, 20% solution; Dainippon Ink and Chemicals, Inc.) 30 parts, phthalate ester 3.5 parts, ZnO whisker 10 as conductive agent
Parts and 0.4 parts of ultramarine blue as a colorant were added to MEK, and dispersed and mixed using a disper to prepare a coating liquid for forming a reflection (undercoat) layer having a viscosity of 0 Pa · s (20 ° C.). After evenly coating on a 300 μm thick polyethylene terephthalate support,
After drying the coating film, a reflective layer (layer thickness: 20 μm) is formed on the support.
m) formed.

Further, the phosphor sheet prepared above was placed on the reflection layer formed on the support and compressed. Compression was performed continuously using a calender roll under the conditions of a pressure of 50 MPa, an upper roll temperature of 90 ° C., a lower roll temperature of 75 ° C., and a feed speed of 2.0 m / min. By this compression, the phosphor sheet and the support were completely fused.
The thickness of the phosphor layer after fusion was 220 μm.

Next, a protective layer was formed. 50 parts of a fluoroolefin / vinyl ether copolymer (Lumiflon LF-504X (40% solution), manufactured by Asahi Glass Co., Ltd.) as a fluorine resin, and a polyisocyanate (Sumidur N3500,
9 parts of Sumitomo Chemical Co., Ltd., 0.3 parts of reactive silicone (Silaprene FM-DA26, manufactured by Chisso Corporation) as a slip agent, and dibutyltin dilaurate (KS1260, Kyodo Chemical Co., Ltd.) as a catalyst
0.003 parts, Eposter S as melamine resin particles
6) 10 parts were dissolved in MEK to prepare a coating solution having a viscosity of 30 mPa · s. This coating solution was applied on 9 μm polyethylene terephthalate, heat-treated at 120 ° C. for 30 minutes, thermally cured, and dried.After that, a polyester-based adhesive layer was provided on the back surface, and the adhesive layer and the phosphor layer were 100 A protective film was formed by heat deposition at 5 ° C. and 5 ° C.

Lastly, border application was performed. 70 parts of a silicone polymer (polyurethane having a polydimethylsiloxane unit, dialomer SP-3023 (15 wt% solution (solvent: mixed solvent of MEK and toluene), manufactured by Dainichi Seika Co., Ltd.)) 70 parts, polyisocyanate (cross Nate D-70 (50 wt% solution, manufactured by Dainichi Seika Co., Ltd.) 3 parts, epoxy resin (EP1001 (solid); Yuka Shell Epoxy Co., Ltd.) as a yellowing inhibitor 0.6
Parts, reactive silicone (Silaprene F
0.13 parts of M-DA26 (manufactured by Chisso Corporation) was added to 15 parts of MEK and dissolved to prepare a coating solution for forming an edge bonding.

A coating solution for forming an edge bond is applied to each side surface of the panel composed of the support, the reflective layer, the phosphor layer, and the protective film prepared above, and dried sufficiently at room temperature to obtain an edge having a thickness of 25 μm. Form a cured paste film, support, undercoat layer, phosphor layer,
A radiation image conversion panel composed of a protective film and a cured edge film was produced.

(Example 2) In Example 1, a comb-shaped copolymer having a plurality of basic functional groups in the molecular side chain of the phosphor sheet composition was prepared, and one basic functional group was provided at the molecular end. A radiation image conversion panel was manufactured in the same manner except that Solsperse 9000, a linear polymer, was used.

Example 3 Radiation was carried out in the same manner as in Example 1 except that the amount of the comb copolymer having a plurality of basic functional groups in the molecular side chain of the phosphor sheet composition was reduced to 1 part. An image conversion panel was manufactured.

Comparative Example 1 A radiation image conversion panel was prepared in the same manner as in Example 1, except that no comb copolymer having a plurality of basic functional groups was added to the molecular side chains of the phosphor sheet composition. Was manufactured.

(Comparative Example 2) In Comparative Example 1, instead of the polyurethane resin used as the binder of the phosphor sheet,
Isophorone diisocyanate / adipic acid / 1,6-hexanediol / neopentyl glycol = 50/20/20/1
A radiation image conversion panel was obtained in the same manner except that polyurethane of 0, SO ₃ Na = 10 ⁻⁶ mol / g was used.

Comparative Example 3 In Example 1, a comb-shaped copolymer having a plurality of acidic functional groups was used instead of the comb-shaped copolymer having a plurality of basic functional groups in the molecular side chain of the phosphor sheet composition. A radiation image storage panel was obtained in the same manner except that Solsperse 26000 which was a copolymer was used.

(Evaluation of Image Quality of Radiation Image Conversion Panel) After irradiating the radiation image conversion panel with X-rays having a tube voltage of 80 kVp, H
Excite the phosphor by scanning with e-Ne laser light (632.8 nm),
The stimulated emission emitted from the phosphor layer was received and converted into an electric signal, which was reproduced as an image by an image reproducing device to obtain an image on a display device. The amount of stimulated emission was measured from the obtained phosphor layer, the sharpness was determined by the modulation transfer function (MTF) (spatial frequency: 2 cycles / mm) of the obtained image, and the granularity at a dose of 0.1 mR ( RM). Irradiation unevenness 3c inside the radiation image conversion panel of 35.5cm square
It was divided into m-squares and evaluated by the difference between the average values of the light emission amounts of the respective sections. Table 1 shows the results.

[0064]

[Table 1] As is clear from the above results, the radiation image conversion panel of the present invention is composed of a copolymer having one functional group at a molecular terminal or a comb-type copolymer having a plurality of functional groups on a molecular side chain. Since a polymer dispersant is contained in the phosphor layer, the phosphor particles can be uniformly dispersed in the phosphor layer, and the light emission amount, sharpness, and granularity are equal to or higher than those of the conventional, and the light emission unevenness is significantly increased. An improved radiation image conversion panel having improved and less image unevenness was obtained.

On the other hand, as in the conventional case, a binder having a functional group at random or non-uniformly in part of a linear molecule is used (Comparative Examples 1 and 2). With the polymer dispersant (Comparative Example 3), the emission unevenness was not improved.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a radiation-emitting panel according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a comb copolymer.

[Explanation of symbols]

 Reference Signs List 1 phosphor layer 2 protective layer 3 support

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01T 1/00 G01T 1/00 B G03B 42/02 G03B 42/02 B

Claims (4)

[Claims] 1. A radiation-emitting panel comprising at least a support and a phosphor layer provided on the support, wherein the phosphor layer has a phosphor and a copolymer having one functional group at a molecular end. A radiation-emitting panel, comprising: a polymer dispersant comprising a combined copolymer or a comb-shaped copolymer having a plurality of functional groups in a molecular side chain. 2. The radiation-emitting panel according to claim 1, wherein the functional group is a basic-type functional group. 3. The radiation-emitting panel according to claim 1, wherein the amount of the polymer dispersant added is 0.001% by weight to 1% by weight based on the phosphor. 4. The radiation-emitting panel according to claim 1, wherein the phosphor is a stimulable phosphor.