JP2001021694A - Producing method of radiation image conversion panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a producing method of radiation image conversion panel superior in sharpness and graininess. SOLUTION: Whole process is constituted of at least a phosphor sheet forming process forming a phosphor sheet consisting of combining agent and stimulable phosphor, a layering process for obtaining layering body by layering without adhering and fixing the phosphor sheet onto a support, and a heating and compressing process for compressing the phosphor sheet and adhering to the support by pressing the obtained layering body at a temperature over softening temperature or the melting point of the combining agent. The heating and compressing process is a process for inserting in the nip part of a pair of heated and pressed rolls. The temperature of the roll surface in contact with the support side surface of the layering body is set higher than that of the roll surface of the phosphor sheet side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a radiation image conversion panel used in 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 stimulable phosphor (hereinafter simply referred to as "phosphor") described in, for example, JP-A-55-12145.
There is a case. ) Is known. This method utilizes a radiation image conversion panel (also referred to as a stimulable phosphor sheet) containing a stimulable phosphor, and transmits radiation transmitted through a subject or generated from a subject to the phosphor of the panel. Then, the phosphor is excited by electromagnetic waves (excitation light) such as visible light and infrared light in a time series manner, so that the radiation energy stored in the phosphor is converted into fluorescence (stimulated light). Emission, photoelectrically read this fluorescence to obtain an electric signal,
A radiation image of a subject or a subject is reproduced as a visible image based on the obtained electric signals.

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. Therefore, this method is very useful especially in linear medical radiography such as X-ray radiography for medical diagnosis.

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 one side thereof (hereinafter, may be simply referred to as "phosphor layer"). It consists of: When the phosphor layer is self-supporting, a support is not necessarily required. In general, a transparent protective layer is provided on the surface of the phosphor layer opposite to the support (the surface not facing the support), so that the phosphor layer is chemically altered or Protects against physical shock.

The phosphor layer is generally composed of a phosphor and a binder containing and supporting the phosphor in a dispersed state. The phosphor absorbs radiation such as X-rays and then irradiates with excitation light. It has a property of emitting light. Therefore,
Radiation transmitted through the subject or emitted from the subject is absorbed by the stimulable phosphor layer of the radiation image conversion panel in proportion to the radiation dose, and the radiation image of the subject or the subject is reflected on the panel by radiation energy. Formed as an accumulated 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 radiographic image conversion method is a very useful image forming method as described above, the radiographic image conversion panel used in this method also has a high image quality, like the intensifying screen used in the conventional radiographic method. It is desired to provide an image with high sensitivity and good image quality (sharpness, granularity, etc.).

[0007] The sensitivity of the radiation image conversion panel basically depends on the total stimulating light emission amount of the phosphor contained in the radiation image conversion panel, and the total light emission amount depends only on the light emission luminance of the phosphor itself. It depends on the phosphor content in the phosphor layer. A high content of the phosphor means that the absorption of radiation such as X-rays is also large, so that higher sensitivity can be obtained and at the same time image quality (particularly, 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.

As one of the radiation image conversion panels having a phosphor layer densely filled with phosphors, the applicant of the present application has disclosed a radiation image 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).

In the above-described radiation image conversion panel, the density of the phosphor in the phosphor layer is made higher than that of the conventional radiation image conversion panel by compressing the phosphor layer. As a result, this radiation image conversion panel had excellent sharpness, but on the other hand, the phosphor was partially destroyed by the compression treatment, so that it might be rather deteriorated in terms of granularity. There was a problem.

As a method for solving this, Japanese Patent Laid-Open No. 2-2
No. 78198 discloses that a phosphor sheet serving as a phosphor layer is separately prepared, and then heated and compressed together with a support at a temperature higher than a softening temperature or a melting point of the phosphor layer to compress the phosphor sheet. And a method for simultaneously bonding to a support. According to this method, the filling rate of the phosphor can be improved without destroying the phosphor crystal, and at the same time, the phosphor can be oriented and the phosphor layer can be thinned. Therefore, it has become possible to manufacture a radiation image conversion panel having excellent sharpness and granularity by the method. This method is extremely useful, but further improvement is desired and is being studied continuously.

[0011] The heating and compression treatment is usually performed by inserting a laminate composed of a phosphor sheet and a support into the nip portion of a pair of heated rolls. The control has not been performed, or has been performed by increasing the temperature of the roll surface on the phosphor sheet side.

[0012]

Accordingly, the present invention provides
A method for producing a radiation image conversion panel, in which a phosphor sheet to be a phosphor layer is separately prepared and heated and compressed at a temperature equal to or higher than the softening temperature or the melting point of the phosphor layer together with the support, and further sharpened. An object of the present invention is to provide a manufacturing method capable of manufacturing a radiation image conversion panel excellent in degree and granularity.

[0013]

The above object is achieved by the present invention described below. That is, the present invention, at least,
A phosphor sheet forming step of forming a phosphor sheet comprising a binder and a stimulable phosphor, and a laminating step of laminating the phosphor sheet on a support without bonding and fixing the same to obtain a laminate. By pressing the laminate at a temperature equal to or higher than the softening temperature or the melting point of the binder,
A heating and compressing step of compressing the phosphor sheet and bonding the phosphor sheet to the support, wherein the heating and compressing step is performed at a nip portion of a pair of heated and pressurized rolls. A step of inserting the laminate, wherein the temperature of the roll surface in contact with the support-side surface of the laminate is set higher than the temperature of the roll surface on the phosphor sheet side of the radiation image conversion panel It is a manufacturing method.

The temperature of the pair of rolls in the heating and compression step is set higher than the temperature of the other roll in contact with the surface of the laminate on the phosphor sheet side, so that the support can pass through the support. The generated heat uniformly heats the phosphor layer in the thickness direction. As a result, the compression becomes more uniform in the thickness direction, and a more excellent sharpness and granular radiation image conversion panel can be manufactured.

In the present invention, the temperature difference between the pair of roll surfaces is preferably in the range of 5 to 100 ° C., and the temperature of the roll surface that comes into contact with the phosphor sheet side surface of the laminate is adjusted to , Preferably in the range of 20 to 150 ° C.

Further, in the present invention, it is preferable that the phosphor sheet formed in the phosphor sheet forming step further contains a polyisocyanate, and the binder in the phosphor sheet is a thermoplastic elastomer. preferable.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a radiation image storage panel of the present invention will be described in detail below. The present invention provides a phosphor sheet forming step of forming a phosphor sheet comprising at least a binder and a stimulable phosphor, and laminating the phosphor sheet on a support without bonding and fixing the phosphor sheet. The resulting laminating step, the resulting laminate, by pressing the laminate at a temperature equal to or higher than the softening temperature or the melting point of the binder, a heat compression step of compressing the phosphor sheet and bonding to the support. , Consisting of The phosphor layer of the radiation image conversion panel obtained by going through such a process,
The porosity is low and the filling rate is high. In the radiation image conversion panel, a protective layer is generally provided on the phosphor layer.

Hereinafter, the respective manufacturing steps of the present invention, the protective layer generally provided on the phosphor layer, and other configurations will be sequentially described.

1) Phosphor Sheet Forming Step The phosphor sheet serving as the phosphor layer of the radiation image conversion panel is:
It can be formed by applying a coating solution in which a stimulable phosphor is uniformly dispersed in a binder solution on a temporary support for forming a phosphor sheet, drying and peeling off the temporary support.

The phosphor used in the present invention will be described below. The stimulable phosphor is a phosphor that emits stimulable light when irradiated with radiation and then with excitation light as described above, but from a practical viewpoint, the wavelength is 400 to 900 n.
It is desirable that the phosphor exhibit a photostimulated emission in the wavelength range of 300 to 500 nm by the excitation light in the range of m.
Examples of the stimulable phosphor used in the method for producing a radiation image storage panel of the present invention include:

BaSO ₄ : AX described in JP-A-48-80487 and JP-A-48-80489
No. SrSO disclosed in Japanese _4: phosphor represented by AX, JP Li ₂ are described in 53-39277 JP _{B 4 O 7: Cu, Ag} , JP 54-47883 JP Li ₂ O · listed in _{(B 2 O 2) x:} Cu and _{Li 2 O · (B 2 O} 2) x: Cu, Ag,

SrS: Ce, Sm, SrS: Eu, S described in US Pat. No. 3,859,527.
m, ThO ₂ : Er, and La ₂ O ₂ S: Eu, Sm,
Zn described in JP-A-55-12142
S: Cu, Pb, BaO.xAl ₂ O ₃ : Eu (however,
0.8 ≦ x ≦ 10) and M ^II O.xSiO ₂ : A
(However, M ^II is Mg, Ca, Sr, Zn, Cd, or Ba, and A is Ce, Tb, Eu, Tm, Pb, T
l, Bi, or Mn, and x is 0.5 ≦ x ≦ 2.
5),

(Ba _1-xy , Mg _x , Ca _y ) FX: aEu described in JP-A-55-12143
²⁺ (where X is at least one of Cl and Br, x and y are 0 <x + y ≦ 0.6 and x
y ≠ 0, a is 10 ⁻⁶ ≦ a ≦ 5 × 10 ⁻² ), and LnOX: xA described in JP-A-55-12144 (where Ln is La, Y, Gd , And Lu, X is at least one of Cl and Br, A is at least one of Ce and Tb, and x is 0 <x <0.1),

(Ba _1-x , M ²⁺ _x ) FX: yA described in JP-A-55-12145 (where M ²⁺ is Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Zn) ²⁺ , and at least one of Cd ²⁺ , X is at least one of Cl, Br, and I, A is Eu, Tb, Ce, Tm, Dy,
At least one of Pr, Ho, Nd, Yb, and Er, and x is 0 ≦ x ≦ 0.6, and y is 0 ≦ y ≦
0.2) and BaFX: xCe. Described in JP-A-55-843897. Phosphor represented by yA

M ^II FX · xA: yLn described in JP-A-55-160078 [where M ^II is B
at least one of a, Ca, Sr, Mg, Zn, and Cd, A is BeO, MgO, CaO, SrO, B
aO, ZnO, Al ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , In
₂ O ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , GeO ₂ , Sn
At least one of O ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , and ThO ₂ , Ln is Eu, Tb, Ce, Tm, Dy, P
at least one of r, Ho, Nd, Yb, Er, Sm, and Gd, X is at least one of Cl, Br, and I, and x and y are each 5 × 10
^-5 ≦ x ≦ 0.5, and 0 <y ≦ 0.2].

[0026] Japanese Patent Application Laid-Open No. 56-116777 discloses
(Ba_1-x, M^II _x) F_Two・ ABaX_Two: YEu,
zA [where M^IIIs beryllium, magnesium, cal
Cium, strontium, zinc, and cadmium sac
X is chlorine, bromine, and iodine
A is zirconium and scandi
At least one of a, x, y, and
And z are 0.5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1, 1 respectively.
0^-6≦ y ≦ 2 × 10^-1, And 0 <z ≦ 10 ^-2Is]
A phosphor represented by the composition formula:

(Ba _{1 -x} , M ^II _x ) F ₂ .aBaX ₂ : yEu, z described in JP-A-57-23673.
B [where M ^II is at least one of beryllium, magnesium, calcium, strontium, zinc, and cadmium, X is at least one of chlorine, bromine, and iodine, and a, x, y, and z are 0.5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1, 10 ⁻⁶ ≦ y ≦
2 × 10 ⁻¹ and 0 <z ≦ 10 ⁻¹ ],

(Ba _{1 -x} , M ^II _x ) F ₂ .aBaX ₂ : yEu, z described in JP-A-57-23675
A [where M ^II is at least one of beryllium, magnesium, calcium, strontium, zinc, and cadmium, X is at least one of chlorine, bromine, and iodine, and A is at least one of arsenic and silicon. And a, x, y, and z are each 0.
5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1, 10 ⁻⁶ ≦ y ≦ 2 × 10
^-1 and 0 <z ≦ 5 × 10 ⁻¹ ],

M ^III OX: xCe described in JP-A-58-69281 [where M ^III is Pr, N
d, Pm, Sm, Eu, Tb, Dy, Ho, Er, T
at least one trivalent metal selected from the group consisting of m, Yb, and Bi, X is one or both of Cl and Br, and x is 0 <x <
0.1], a phosphor represented by a composition formula:

Ba _1-x M _{x / 2} L _{x / 2} FX: yEu ²⁺ described in JP-A-58-206678 [provided that
M represents at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs;
Are Sc, Y, La, Ce, Pr, Nb, Pm, Sm,
Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, A
represents at least one trivalent metal selected from the group consisting of 1, Ga, In, and Tl; X represents Cl, Br,
And x represents 10 ⁻² ≦ x ≦ 0.5, and y satisfies 0 <y ≦ 0.1], and a phosphor represented by a composition formula:

BaFX.xA: yEu ²⁺ described in JP-A-59-27980 [where X is C
A is at least one halogen selected from the group consisting of l, Br, and I; A is a calcined product of a tetrafluoroborate compound; and x is 10 ⁻⁶ ≦ x ≦ 0.
1, y is 0 <y ≦ 0.1], a phosphor represented by a composition formula:

[0032] xM ₃ (PO ₄₎ as described in _{JP-A-59-38278 2 · NX 2: yA,} M 3 (P
O ₄ ) ₂ : yA and nReX ₃ .mAX ′ ₂ : xEu, n
_{ReX 3 · mAX '2: xEu} , ySm, M I X · AM II
X ′ ₂ .bM ^III X ″ ₃ : a phosphor represented by cA,

BaFX.xA: yEu ²⁺ described in JP-A-59-47289, wherein X is C
A is at least one halogen selected from the group consisting of l, Br and I; A is hexafluorosilicic acid,
It is a calcined product of at least one compound selected from the group of hexafluoro compounds consisting of monovalent or divalent metal salts of hexafluorotitanic acid and hexafluorozirconic acid; and x is 10 ⁻⁶ ≦ x ≦ 0.1 , Y is 0
<Y ≦ 0.1], a phosphor represented by a composition formula:

BaFX.xNaX ': aEu ²⁺ described in JP-A-59-56479, wherein X and X' are at least one of Cl, Br and I, respectively, a is 0 <x ≦
2, and 0 <a ≦ 0.2], a phosphor represented by M ^II FX.xNaX ′: yEu ²⁺ : zA described in JP-A-59-56480.
M ^II is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; X and X ′ are at least one halogen selected from the group consisting of Cl, Br, and I, respectively. Yes; A is V,
X is at least one transition metal selected from Cr, Mn, Fe, Co, and Ni; and x is 0 <x ≦
2, y is 0 <y ≦ 0.2, and z is 0 <z ≦ 10 ^-2 ].

[0035] M ^II FX · aM are described in JP 59-75200 Publication ^{I X '· bM' II X} "2 · cM III
X "'3.xA: yEu2 + [where M ^II is Ba,
Sr, and is at least one alkaline earth metal selected from the group consisting of Ca; M ^I is Li, Na, K,
Rb, and is at least one alkali metal selected from the group consisting of Cs; M ^'II is at least one trivalent metal selected from the group consisting of Be and Mg;
M ^III is at least one trivalent metal selected from the group consisting of Al, Ga, In, and Tl; A is a metal oxide; X is at least one selected from the group consisting of Cl, Br, and I X ',
X ″ and X ″ ″ are at least one halogen selected from the group consisting of F, Cl, Br, and I;
A is 0 ≦ a ≦ 2, b is 0 ≦ b ≦ 10 ⁻² , and c is 0
≦ c ≦ 10 ⁻² and a + b + c ≧ 10 ⁻⁶ ; x is 0
<X ≦ 0.5, y is 0 <y ≦ 0.2], a phosphor represented by a composition formula:

M ^II X ₂ · aM ^II X ′ ₂ : xEu ²⁺ described in JP-A-60-84381 [where M ^II
Is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; X and X 'are C
at least one halogen selected from the group consisting of l, Br and I, and X ≠ X ′; and a
Is 0.1 ≦ a ≦ 10.0 and x is 0 <x ≦ 0.2]
A stimulable phosphor represented by the composition formula:

The M ^II FX · aM ^I X are described in JP 60-101173 Laid ': xEu ²⁺ [However, M
^II is Ba, is at least one alkaline earth metal selected from the group consisting of Sr and Ca; M ^I is at least one alkali metal selected from the group consisting of Rb and Cs; X is Cl, Br and I X ′ is F, at least one halogen selected from the group consisting of
At least one halogen selected from the group consisting of Cl, Br and I;
≦ a ≦ 4.0 and 0 <x ≦ 0.2], a stimulable phosphor represented by a composition formula:

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 Cl, Br and X is at least one halogen selected from the group consisting of I; and x is 0 <x ≦
And a stimulable phosphor represented by the composition formula:

The M ^II X ₂ .aM ^II X ' ₂ : xEu ²⁺ stimulable phosphor described in the above-mentioned JP-A-60-84381 has the following additives. ^II X ₂ · a
M ^II X ' ₂ may be contained in the following ratio per mole.

[0040] JP-A-60-166379 describes
BM^IX "(where M^IIs from Rb and Cs
At least one alkali metal selected from the group consisting of
X ″ is selected from the group consisting of F, Cl, Br and I
Is at least one halogen, and b is 0 <
b ≦ 10.0); Japanese Patent Application Laid-Open No. 60-221483
BKX ".cMgX 'described in the report_Two・ DM
^IIIX "'_Three(However, M^IIIAre Sc, Y, La, Gd
At least one trivalent selected from the group consisting of
X ″, X ′ and X ″ ″ are all F, C
at least one selected from the group consisting of l, Br and I
Species, 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);
The yB (ta) described in JP-A-60-228592.
However, y is 2 × 10^-Four≦ y ≦ 2 × 10^-1);
The bA described in JP-A-60-228593 (Ta)
However, A is SiO_TwoAnd P_TwoO_FiveSelected from the group consisting of
At least one oxide, and b is 10^-Four≤
b ≦ 2 × 10^-1JP-A-61-120883
BSiO (where b is 0 <b ≦)
3 × 10^-2JP-A-61-120885)
BSnX ″ described in_Two(However, X ″ is F, C
at least one selected from the group consisting of l, Br and I
Species b, and b is 0 <b ≦ 10 ^-3In
Described in JP-A-61-235486.
BCsX ″ .cSnX′2 (where X ″ and X ′
Is selected from the group consisting of F, Cl, Br and I
At least one halogen, and b and
c is 0 <b ≦ 10.0 and 10 respectively.^-6≦ c ≦ 2
× 10^-2And JP-A-61-235487.
BCsX ″ · yLn described in the gazette³⁺(However,
X "is 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
a small number selected from the group consisting of r, Tm, Yb and Lu
At least one kind of rare earth element, and b and y are
0 <b ≦ 10.0 and 10 respectively^-6≦ y ≦ 1.8 ×
10^-1Is).

Among the above stimulable phosphors, 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 phosphor, and any phosphor can be used as long as the phosphor exhibits stimulable emission when irradiated with radiation and then irradiated with excitation light. There may be.

As described above, the stimulable phosphor and the binder are added to an appropriate solvent and mixed well to prepare a coating solution in which the stimulable phosphor is uniformly dispersed in the binder solution. I do. As the binder, a thermoplastic elastomer having elasticity at normal temperature and having fluidity 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,
Examples include chlorinated polyethylene, styrene-butadiene rubber, silicone rubber, and copolymers thereof.

Of the above-mentioned thermoplastic elastomers, those having a softening temperature or a melting point of 20 ° C. to 150 ° C. are generally used, and those having a softening temperature or 30 ° C. to 130 ° C. are preferable.
It is more preferable to use one having a temperature of 30 ° C to 100 ° C.

Examples of the solvent for preparing the coating solution include lower alcohols such as methanol, ethanol, n-propanol and n-butanol; hydrocarbons containing a chlorine atom such as methylene chloride and ethylene chloride; acetone, methyl ethyl ketone and methyl isobutyl ketone. Ketones; esters of lower fatty acids such as methyl acetate, ethyl acetate and butyl acetate with lower alcohols; ethers such as dioxane, ethylene glycol monoethyl ether and ethylene glycol monomethyl ether; 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 kind of the phosphor, and the like. Is selected in the range of 1: 1 to 1: 100 (weight ratio), and particularly preferably in the range of 1: 8 to 1:40 (weight ratio).

In order to form a phosphor layer having higher mechanical strength, it is preferable to add a crosslinking agent to the coating solution. By adding the cross-linking agent, the binder constituting the phosphor layer is cross-linked, and a phosphor layer having high mechanical strength is formed. The crosslinking agent that can be used is not particularly limited, and examples thereof include a polyisocyanate, a melamine resin, a melamine-based amino resin, a benzoguanamine-based amino resin, a urea resin, a polyamide resin, and an acrylic resin. Among them, polyisocyanate has compatibility with various resins, and is preferable from the viewpoint of non-yellowing and flexibility.

The addition amount of the crosslinking agent in the coating solution is as follows:
Although it depends on the type of the binder and the cross-linking agent and cannot be unconditionally determined, it is preferably in the range of 0 to 50% by weight, more preferably 3 to 30% by weight, based on the binder.

The coating solution contains a dispersant for improving the dispersibility of the phosphor in the coating solution, and a binding force between the binder and the phosphor in the formed phosphor layer. Various additives such as a plasticizer for improving and an anti-yellowing agent may be mixed. Examples of dispersants used for such purposes include phthalic acid, stearic acid,
Caproic acid, lipophilic surfactants and the like can be mentioned. Examples of the plasticizer include phosphate esters such as triphenyl phosphate, tricresyl phosphate, and diphenyl phosphate;
Phthalates such as diethyl phthalate and dimethoxyethyl phthalate; ethylphthalylethyl glycolate;
Glycolic acid esters such as butyl phthalyl butyl glycolate; and polyesters of polyethylene glycol and fatty acid dibasic acid such as polyesters of triethylene glycol and adipic acid, and polyesters of diethylene glycol and succinic acid.

The coating solution containing the phosphor and the binder prepared as described above is then uniformly applied to the surface of the temporary support for sheet formation to form a coating film of the coating solution. I do. This coating operation is performed by a normal coating means, for example,
It can be performed by using a doctor blade, a roll coater, a knife coater or the like.

The temporary support is, for example, a 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, polyester, polyethylene terephthalate, polyamide, polyimide,
Films of plastic substances such as triacetate and polycarbonate, metal sheets such as aluminum foil and aluminum alloy foil, ordinary paper, baryta paper, resin coated paper, pigment paper containing pigments such as titanium dioxide, paper sized with polyvinyl alcohol, etc. , Alumina, zirconia, magnesium, titania, and other ceramic plates or sheets.

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.

2) Laminating Step The phosphor sheet formed in the preceding step is laminated on the support without being adhered and fixed to form a laminate with the support. This support can be arbitrarily selected from the same materials as the temporary support used when forming the phosphor sheet.

In a known radiation image conversion panel, the phosphor layer is used to strengthen 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 which the surface is provided to form an adhesion-imparting layer, or a light-reflective layer made of a light-reflective material such as titanium dioxide, or a light-absorbing material such as carbon black It is known to provide a light absorbing layer made of 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.

Further, as described in JP-A-58-200200, in order to improve the sharpness of the obtained image, the surface of the support on the side of the phosphor layer (the side of the support on the side of the phosphor layer) is used. When an adhesiveness-imparting layer, a light-reflecting layer, a light-absorbing layer, or the like is provided on the surface of the substrate (which means the surface), fine irregularities may be formed.

3) Heat Compression Step The laminate obtained in the preceding step is compressed (heat-compressed) at a temperature not lower than the softening temperature of the binder or not lower than the melting point thereof, so that the phosphor sheet is compressed. Adhere to the support. The heat compression at this time is generally performed by inserting the laminate into a nip portion of a pair of heated rolls (so-called calender rolls). At this time, it may be continuously inserted through a plurality of pairs of rolls. In addition, as a material of these rolls, metal, plastic, or the like is used. The insertion speed is generally achieved by passing the sheet at a constant speed.

The pressure at the time of compression is not particularly limited.
It is generally 0 kgw / cm ² or more. In addition,
It is generally preferable that the time between the phosphor sheet forming step and the heating and compressing step be within 10 days, but the same applies to the present invention.

5) Protective Layer In a normal radiation image conversion panel, as described above, on the surface of the phosphor layer opposite to the side in contact with the support, the phosphor layer is physically and chemically protected. Is provided with a transparent protective layer (transparent protective layer). Such a transparent protective layer is preferably provided also for a radiation image conversion panel according to the production method of the present invention.

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

6) Other Structures The radiation image conversion panel has an edge-adhering layer on at least one end (side surface) of the radiation image conversion panel in order to improve transport resistance, particularly impact resistance and contamination resistance. Can be provided.

The coating agent for forming the border layer is not particularly limited. For example, a linear polyester or a linear polyester and a vinyl chloride / vinyl acetate copolymer described in JP-A-62-3700 can be used. And an organic solvent-soluble fluororesin described in JP-A-4-2998. Also, Japanese Patent Laid-Open No. 7-14
No. 0300, which includes a silicone-based polymer and a polyisocyanate in detail. A radiation image storage panel having an edge-adhered layer formed with such a coating material has extremely high transport resistance, particularly impact resistance. And contamination resistance can be achieved.

The radiation image conversion panel is manufactured as described above. For the purpose of improving the sharpness of the obtained image, at least one of the above-mentioned layers (excluding the bordering layer) is colored with a coloring agent that absorbs the excitation light and does not absorb the stimulated emission light. (See JP-B-59-23400).

In the present invention, the heating and compressing step comprises:
This is a step of inserting the laminate into the nip portion of a pair of heated rolls, wherein the temperature of the other roll surface is set higher than the temperature of the roll surface in contact with the phosphor sheet side surface of the laminate. It is essential. By doing so, the heat passing through the support heats the phosphor layer more uniformly in the thickness direction. As a result, the compression becomes more uniform in the thickness direction, and a more excellent sharpness and granular radiation image conversion panel can be manufactured.

In the present invention, the temperature difference between the pair of roll surfaces is preferably in the range of 5 to 100 ° C., more preferably in the range of 10 to 80 ° C.
The temperature is more preferably in the range of 20 to 70 ° C. 5 ℃
When the temperature difference approaches, the effect of the present invention is not sufficiently obtained. On the other hand, when the temperature difference exceeds 100 ° C.,
Due to too much heat passing through the support, the phosphor layer is not uniformly heated in the thickness direction. As a result, uniform compression may not be performed.

The temperature of the roll in contact with the surface of the laminate on the phosphor sheet side must be not less than the softening temperature or the melting point of the binder, but the upper limit is not more than 150 ° C. The temperature is preferably 130 ° C. or lower, more preferably 100 ° C. or lower. If the temperature exceeds 150 ° C., depending on the material used, the phosphor sheet may be too soft, so that uniform compression may not be performed.

[0065]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Comparative Example 1 (1) Formation of Phosphor Sheet (Composition of Coating Solution for Phosphor Sheet Formation) Phosphor: BaFBr _0.85 I _0.15 : Eu ²⁺ 200 g Binder: polyurethane elastomer (Dainippon Ink Chemicals) Industrial Co., Ltd., Bandex T-5265H) 7.4 g Crosslinking agent: polyisocyanate (Coronate HX manufactured by Nippon Polyurethane Co., Ltd.) 0.6 g Additive: Epoxy resin (Yuika Shell Epoxy Co., Ltd., Epi Coat 1001) 2 g

The material having the above composition was added to methyl ethyl ketone, and dispersed using a propeller mixer.
(25 ° C.) A phosphor sheet forming coating solution was prepared. This was applied on polyethylene terephthalate (temporary support, thickness 180 μm) coated with a silicone release agent, dried, and then peeled off from the temporary support to form a phosphor sheet. The obtained phosphor sheet was stored for 7 days.

(2) Formation of Undercoat Layer (Light Reflecting Layer) (Composition of Undercoat Layer-Forming Coating Solution) Fine particles of gadolinium oxide (Gd ₂ O ₃ ) (particles of 90% by weight of the preceding particles) Binder: Soft acrylic resin (Chriscoat P-1018GS, 20% by weight solution, manufactured by Dainippon Ink and Chemicals, Inc.) 150 g Low molecular weight organic component: ethyl Phthalylethyl glycolate 3.0 g Conductive agent: ZnO whisker 10 g Colorant: ultramarine 0.4 g

The material having the above composition was replaced with methyl ethyl ketone 22
In addition to 0 g, the mixture was dispersed using a propeller mixer to prepare a coating solution for forming an undercoat layer having a viscosity of 6 PS (25 ° C.). 300 μm thick polyethylene terephthalate (support)
Is placed horizontally on a glass plate, and the above coating liquid for forming an undercoat layer is uniformly applied on a support using a doctor blade. Then, the coating film is dried, and the undercoat layer (light (Reflection layer) (thickness of undercoat layer: 20 μm).

(3) Laminating Step and Heat Compression Step The support having the undercoat layer formed thereon in the step of “(2) Formation of the undercoat layer” is provided with “(1) Fluorescence on the undercoat layer side surface”. The phosphor sheet prepared in the step of “formation of body sheet” and stored for 7 days was mounted (not adhered and fixed at this stage) to obtain a laminate, and the laminate was heated and compressed. The heat compression was performed using a calender roll at a pressure of 500 kgw / cm ² , the surface temperatures of the pair of rolls were both 45 ° C., and the feed rate was 0.4 m / min. Was performed continuously under the following conditions. By this compression, the phosphor sheet and the support were completely fused, and the phosphor sheet became a phosphor layer. The thickness of the phosphor layer after fusion was 210 μm.

(4) Formation of Transparent Protective Layer After the above heat compression treatment, a transparent film of polyethylene terephthalate (thickness: 10 μm) coated with a polyester-based adhesive on one side was placed with the adhesive side on the phosphor layer side. The transparent protective layer was formed by adhering to the substrate. As described above, the support, the undercoat layer (light reflection layer), the phosphor layer,
In addition, a radiation image storage panel of Example 1 including a transparent protective layer was manufactured.

Example 1 In Comparative Example 1, the phosphor sheet was stored for one day, and the surface temperature of a pair of calender rolls was changed to the upper roll (side in contact with the phosphor layer).
A radiation image conversion panel was manufactured in the same manner as in Example 1 except that the temperature was 45 ° C., and the temperature of the lower roll (the side in contact with the support) was 60 ° C.

Example 2 A radiation image conversion panel was manufactured in the same manner as in Example 1 except that the phosphor sheet was stored for 14 days.

Comparative Example 2 A radiation image conversion panel was manufactured in the same manner as in Example 1, except that the phosphor sheet was stored for 14 days.

[Evaluation of Image Quality of Radiation Image Conversion Panel] Examples 1-2 and Comparative Examples 1-2 produced as described above.
The image quality of each of the radiation image conversion panels was evaluated by the method described below.

That is, after irradiating each radiation image conversion panel with X-rays having a tube voltage of 80 KVp, it is scanned with a He-Ne laser beam (632.8 nm) to excite the phosphor in the phosphor layer. The stimulated emission emitted from the 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. Modulation transfer function (MTF) of the obtained image (air conditioning frequency: 2 cycles / m
m) to determine the sharpness and the granularity (RMS) at a dose of 0.1 mR. The obtained results are shown in Table 1 below.
Shown in

[0077]

[Table 1]

As is clear from Table 1, the radiation image conversion panels of Examples 1 and 2 in which the lower roll was set higher than the upper roll had good sharpness and granularity. It can be seen that the samples have good sharpness and granularity even when the storage days are 14 days.

[0079]

As described above, according to the manufacturing method of the present invention, a radiation image conversion panel having extremely excellent sharpness and granularity can be manufactured.

Claims (6)

[Claims] 1. A phosphor sheet forming step of forming a phosphor sheet comprising at least a binder and a stimulable phosphor, and laminating the phosphor sheet on a support without bonding and fixing the phosphor sheet. And a heat compression step of compressing the phosphor sheet and bonding it to the support by pressing the laminate at a temperature equal to or higher than the softening temperature or the melting point of the binder. Wherein the heating and compressing step is a step of inserting the laminate into a nip portion of a pair of heated and pressurized rolls; A method of manufacturing a radiation image conversion panel, wherein a temperature of a roll surface in contact with a surface is set higher than a temperature of a roll surface on the phosphor sheet side. 2. The temperature difference between the pair of roll surfaces is 5 to 5.
The method according to claim 1, wherein the temperature is in a range of 100C. 3. The method of manufacturing a radiation image conversion panel according to claim 1, wherein the temperature of the roll surface in contact with the phosphor sheet side surface of the laminate is 150 ° C. or less. 4. The method of manufacturing a radiation image conversion panel according to claim 1, wherein a period between the phosphor sheet forming step and the heat compression step is set within 10 days. 5. The method of manufacturing a radiation image storage panel according to claim 1, wherein the phosphor sheet formed in the phosphor sheet forming step further contains a polyisocyanate. 6. The manufacturing method of a radiation image storage panel according to claim 1, wherein the binder in the phosphor sheet formed in the phosphor sheet forming step is a thermoplastic elastomer. Method.