JP2549912B2 - Manufacturing method of radiation image conversion panel - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for producing a radiation image conversion panel used in a radiation image conversion method using a stimulable phosphor.

[Technical Background and Prior Art of the Invention] 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 or the like is known. Are known. This method utilizes a radiation image conversion panel (also referred to as a stimulable phosphor sheet) containing a stimulable phosphor,
Radiation transmitted through the subject or generated from the subject is absorbed by the stimulable phosphor of the panel, and then the stimulable phosphor is an electromagnetic wave (excitation light) such as visible light or infrared light.
The radiation energy accumulated in the stimulable phosphor is fluorescent (stimulated luminescence) by being excited in time series with
The fluorescence signal is photoelectrically read to obtain an electric signal, and the radiation image of the subject or the subject is reproduced as a visible image based on the obtained electric signal.

According to this radiographic image conversion method, it is possible to obtain a radiographic image with a large amount of information at a much lower exposure dose compared to the radiographic method using a combination of a conventional radiographic film and an intensifying screen. There is an advantage that you can.
Therefore, this method has a very high utility value especially in linear medical radiography such as X-ray photography for the purpose of 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 surface thereof. In addition, when the phosphor layer is self-supporting, a support is not always necessary. In addition, a transparent protective film is generally provided on the surface of the photostimulable phosphor layer opposite to the support (the surface not facing the support), and the phosphor layer is chemically treated. Protects against severe alteration or physical shock.

The stimulable phosphor layer is generally composed of a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state. The stimulable phosphor layer absorbs radiation such as X-ray and then emits excitation light. It has the property of exhibiting stimulated emission upon irradiation.
Therefore, the 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 subject is radiated on the panel. It is formed as an accumulated image of 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 this stimulated emission light and converting it into an electric signal. It becomes possible to do.

The radiation image conversion method is a very advantageous image forming method as described above, but the radiation image conversion panel used in this method has high sensitivity as in the intensifying screen used in the conventional radiographic method. In addition, it is desired that the image gives a good image quality (sharpness, graininess, etc.).

The sensitivity of the radiation image conversion panel basically depends on the total stimulable emission amount of the stimulable phosphor contained in the panel, and the total luminescence amount depends not only on the emission luminance of the phosphor itself,
It also depends on the content of the phosphor in the phosphor layer. A large content of the phosphor also means a large absorption for radiation such as X-rays, so that higher sensitivity can be obtained and at the same time, image quality (particularly graininess) is improved. on the other hand,
In the case where 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 can be reduced. And a relatively high sharpness can be obtained.

The applicant of the present application, as one of the radiation image conversion panels having a phosphor layer densely packed with a phosphor, a radiation image conversion panel in which the porosity of the phosphor layer is reduced by compressing the phosphor layer. And its manufacturing method have already been applied (see JP-A-59-126299, 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.

[Summary of the Invention] An object of the present invention is to provide a method of manufacturing a radiation image conversion panel capable of reducing the porosity of a phosphor layer without destroying the phosphor.

Another object of the present invention is to provide a method of manufacturing a radiation image storage panel capable of manufacturing a radiation image conversion panel having excellent sharpness and excellent granularity.

The above object is a method for producing a radiation image storage panel of the present invention, which is substantially composed of a support and a phosphor layer composed of a binder and a stimulable phosphor provided on the support. A) a step of forming a phosphor sheet composed of a binder and a stimulable phosphor, b) a step of laminating the phosphor sheet on a support without adhering and fixing it, and c) obtained A step of compressing the phosphor sheet and adhering it to a support by pressing the laminate at a softening temperature of the binder or at a temperature equal to or higher than the melting point of the laminate by calender rolls; This can be achieved by the method of manufacturing the image conversion panel.

In the present invention, the compression of the phosphor sheet to be the phosphor layer is performed at the softening temperature or melting point of the binder or higher and at the same time when the binder is placed on the support. For this reason, at the time of compression, the phosphor crystals dispersed in the binder of the phosphor layer (phosphor sheet) are subjected to pressure with a certain degree of freedom, and the phosphor to be the phosphor layer The sheet is subjected to pressure without being fixed to the support. Therefore, even if the pressure that would break the crystal if the phosphor sheet is fixed,
At the same time it acts to orient the phosphor crystals, and at the same time acts to stretch and unroll the sheet.

That is, according to the present invention, it is possible to improve the filling rate of the phosphor without destroying the phosphor crystal, at the same time, orient the phosphor, and further spread the phosphor layer thinly.

 The preferred embodiments of the present invention are listed below.

(1) A method for producing a radiation image storage panel, wherein the binder is a thermoplastic elastomer.

(2) The binder has a softening temperature or a melting point of 30 to 300 ° C.
A method for producing a radiation image storage panel, which is a thermoplastic elastomer.

(3) The binder has a softening temperature or melting point of 30 to 200 ° C.
A method for producing a radiation image storage panel, which is a thermoplastic elastomer.

(4) The binder has a softening temperature or melting point of 30 to 150 ° C.
A method for producing a radiation image storage panel, which is a thermoplastic elastomer.

(5) A method for producing a radiation image conversion panel, characterized in that, prior to the step b), an adhesion-imparting layer and / or a light-reflecting layer are provided on the support in advance.

(6) A method for manufacturing a radiation image conversion panel, wherein the pressurization in the step b) is performed at a pressure of 50 Kgw / cm ² or more.

[Structure of the Invention] The method for manufacturing the radiation image storage panel of the present invention will be described in detail below.

The method for producing a radiation image conversion panel of the present invention comprises: a) a step of forming a phosphor sheet comprising a binder and a stimulable phosphor; b) laminating the phosphor sheet on a support without adhering and fixing the same. And c) a step of applying the obtained laminate to a calendar roll and pressing the laminate at a temperature equal to or higher than the softening temperature or melting point of the binder, thereby compressing the phosphor sheet and adhering it to the support. It consists of.

 First, step a) will be described.

The phosphor sheet serving as the phosphor layer of the radiation image conversion panel was coated with a coating solution in which the stimulable phosphor was uniformly dispersed in a binder solution on a temporary support for forming the phosphor sheet, and dried. Thereafter, it can be manufactured by peeling off from the temporary support.

The phosphors used in the present invention will be described below.

The stimulable phosphor is a phosphor that emits stimulated emission when irradiated with excitation light after being irradiated with radiation as described above, but from a practical viewpoint, the wavelength is in the range of 400 to 900 nm. A phosphor that exhibits stimulated emission in the wavelength range of 300 to 500 nm by excitation light is desirable. Examples of the stimulable phosphor used in the production process the radiation image storage panel of the present invention, BaSO are described in JP 48-80487 _4: AX and JP 48-80489 Patent Publication Listed SrSO ₄ : AX
In phosphor represented, Li is described in _{JP-A-53-39277 2 B 4 O 7: Cu} ,
Ag, Li ₂ O · (B ₂ O
₂ ) _x : Cu and Li ₂ O. (B ₂ O ₂ ) _x : Cu, Ag, SrS: C described in US Pat. No. 3,859,527.
e, Sm, SrS: Eu, Sm, ThO 2: Er, and _{La 2 O 2 S: Eu,} Sm, are described in JP-A-55-12142 ZnS: Cu, Pb,
BaO.xAl ₂ O ₃ : Eu (where 0.8 ≦ x ≦ 10) and M ^II
O.xSiO ₂ : A (where M ^II is 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), which is described in JP-A-55-12143 (Ba _1-xy , M
g _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, a is 10 ⁻⁶ ≦ a ≦ 5 × 10 ⁻² ), and LnOX: xA described in JP-A-55-12144 (where Ln is La, At least one of 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), described in JP-A-55-12145 (Ba _1-x , M ²⁺
_x ) FX: yA (where M ²⁺ is at least one of Mg, Ca, Sr, Zn, and Cd, X is at least one of Cl, Br, and I, A is Eu, Tb, Ce, Tm, Dy, Pr, Ho, N
at least one of d, Yb, and Er, and x
Is 0 ≦ x ≦ 0.6, and y is 0 ≦ y ≦ 0.2), BaFX: xCe.y described in JP-A-55-84387.
M ^II FX · xA listed in the phosphor Sho 55-160078 discloses represented by A:
yLn [where M ^II is at least one of Ba, Ca, Sr, Mg, Zn, and Cd; A is BeO, MgO, CaO, SrO, BaO, Z
nO, Al ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , In ₂ O ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , G
At least one of eO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , and ThO ₂ , Ln is Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb,
At least one of Er, Sm, and Gd, X is Cl, B
at least one of r and I, wherein x and y are 5 × 10 ⁻⁵ ≦ x ≦ 0.5 and 0 <y ≦ 0.2, respectively] No. 116777 (Ba _1-x , M
^{_{II x) F 2 · aBaX 2}} : yEu, zA [ provided that at least one of the at least one of M ^II is beryllium, magnesium, calcium, strontium, zinc and cadmium,, X is chlorine, bromine, and iodine, A is at least one of zirconium and scandium, 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 ≦ 10 ⁻²
And a phosphor represented by the composition formula (Ba _1-x , M ^II).
_x ) F ₂ · aBaX ₂ : yEu, zB [wherein M ^II is at least one of beryllium, magnesium, calcium, strontium, zinc, and cadmium, X is chlorine, bromine,
And at least one of iodine and a, x,
y and z are respectively 0.5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1, 1
0 ^-6 ≤ y ≤ 2 x 10 ^-1 , and 0 <z ≤ 10 ^-1 ], the phosphor described in JP-A-57-23675 (Ba1 _-x). , M ^II
_x ) F ₂ aBaX ₂ : yEu, zA [where M ^II is at least one of beryllium, magnesium, calcium, strontium, zinc, and cadmium, X is chlorine, bromine,
And at least one of iodine and A is at least one of arsenic and silicon, and a, x, y and z are respectively 0.5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1, 10 ⁻⁶ ≦ y ≦
2 × 10 ⁻¹ and 0 <z ≦ 5 × 10 ⁻¹ ], and M ^III OX: xCe described in JP-A-58-69281.
[However, M ^III is Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, E
at least one trivalent metal selected from the group consisting of r, Tm, Yb, and Bi, X is one or both of Cl and Br, and x is 0 <x <0.1] A phosphor represented by the following formula: Ba _1-x M _{x / 2} described in JP-A-58-206678.
L _{x / 2} FX: _y Eu ²⁺ [where M is Li, Na, K, Rb, and C]
represents at least one alkali metal selected from the group consisting of s; L is Sc, Y, La, Ce, Pr, Nb, Pm, Sm, G
d, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, In, and T
represents at least one trivalent metal selected from the group consisting of l; X represents at least one halogen selected from the group consisting of Cl, Br, and I; and x represents 10 ^-2
.Ltoreq.x.ltoreq.0.5, y is 0 <y.ltoreq.0.1]. BaFX.xA: yE described in JP-A-59-27980.
u ^{2+ wherein} X is at least one halogen selected from the group consisting of Cl, 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] xM ₃ (PO ₄ ) described in JP-A-59-38278
₂・ NX ₂ : yA, M ₃ (PO ₄ ) ₂ : yA and nReX ₃・ mAX ′ ₂ : xEu,
_{nReX 3 · mAX '2: xEu} , ySm, M I X · AM II X' 2 · bM III X "3: c
A phosphor represented by A, BaFXxA: yE described in JP-A-59-47289.
u ²⁺ [where X is at least one halogen selected from the group consisting of Cl, Br and I; A is monovalent or divalent hexafluorosilicic acid, hexafluorotitanic acid and hexafluorozirconic acid] A calcined product of at least one compound selected from the group of hexafluoro compounds consisting of salts of valent metals; and x is 10 ⁻⁶ ≦ x ≦
0.1, y is 0 <y ≦ 0.1], a phosphor represented by the composition formula, BaFX.xNa described in JP-A-59-56479.
X ′: aEu ²⁺ [where X and X ′ are Cl, B
r and at least one of I, and x and a are respectively 0 <x ≦ 2 and 0 <a ≦ 0.2]
The phosphor represented by the composition formula of M ^II FX.xNa described in JP-A-59-56480.
X ′: yEu ²⁺ : zA [where M ^II is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; X and X ′ are Cl, Br, and I, respectively. At least one halogen selected from the group consisting of: A
Is at least one transition metal selected from V, 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 a] phosphor represented by a composition formula of, M ^II FX · aM that is described in JP-A-59-75200
^I X ′ ・ bM ′ ^II X ″ ₂・ cM ^III X ₃・ xA: yEu ²⁺ [However, M
^II is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; M ^I is Li, Na, K, R
b, and at least one alkali metal selected from the group consisting of Cs; M ′ ^II is at least one divalent metal selected from the group consisting of Be and Mg; M ^III is Al, G
a, In, and at least one trivalent metal selected from the group consisting of Tl; A is a metal oxide; X is Cl, Br,
And at least one halogen selected from the group consisting of and I; X ', X ", and X are at least one halogen selected from the group consisting of F, Cl, Br, and I; and a is 0 ≦ a ≦ 2, b is 0 ≦ b ≦ 10 ⁻² ,
c is 0 ≦ c ≦ 10 ⁻² and a + b + c ≧ 10 ⁻⁶ ; x is 0
<X≤0.5, y is 0 <y≤0.2] M ^II X ₂ · aM ^II described in JP-A-60-84381
X ′ ₂ : xEu ²⁺ [where M ^II is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; X and X ′ are selected from the group consisting of Cl, Br and I A stimulable phosphor represented by a composition formula of at least one halogen and X 、 X ′; and a is 0.1 ≦ a ≦ 10.0 and x is 0 <x ≦ 0.2. M ^II FX ・ aM ^I described in JP-A-60-101173
X ′: xEu ²⁺ [wherein M ^II is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; M
^I is at least one alkali metal selected from the group consisting of Rb and Cs; X is at least one halogen selected from the group consisting of Cl, Br and I; X 'is F,
At least one halogen selected from the group consisting of Cl, Br and I; and a and x are each 0 ≦ a
≦ 4.0 and 0 <x stimulable phosphor represented by a composition formula of ≦ 0.2 is], M ^I X are described in JP-A-62-25189: xBi [However, M ^I is Rb and Cs Is at least one alkali metal selected from the group consisting of; X is at least one halogen selected from the group consisting of Cl, Br and I; and x is a number in the range 0 <x ≦ 0.2] Examples thereof include stimulable phosphors represented by a composition formula.

Further, M described in JP-A-60-84381 described above
^II X ₂・ aM ^II X ′ ₂ : xEu ²⁺ Stimulable phosphor contains the following additives in the following ratio per mole of M ^II X ₂・ aM ^II X ′ ₂ : Is also good.

JP bM ^I X that are described in 60-166379 JP "(where, M ^I is at least one alkali metal selected from the group consisting of Rb and Cs, X 'is F, Cl, Br and I At least one halogen selected from the group consisting of: and b is 0 <b ≦ 10.0);
BKX ″ · cMgX ₂ · dM ^III X described in Japanese Patent No. 1483
′ ₃ (where M ^III is at least one trivalent metal selected from the group consisting of Sc, Y, La, Gd and Lu,
X ″, X and X ′ are all F, Cl, Br and I
Is 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 ⁻⁵ ≦ b
+ C + d); yB described in JP-A-60-228592 (where y is 2 × 10 ⁻⁴ ≦ y ≦ 2 × 10 ⁻¹ ); JP-A-60-228593. BA as described (where A is at least one oxide selected from the group consisting of SiO ₂ and P ₂ O ₅ , and b is 10 ⁻⁴ ≦ b ≦ 2 ×
10 ^-1 is); bSiO that are described in JP 61-120883 Laid (where, b is 0 <b ≦ 3 is a × 10 ^-2); described in JP-A No. 61-120885 Laid BSnX ″ ₂ (where X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I, and b is 0 <b ≦
10 a ^-3); JP 61-235486 discloses to have bCsX "· cSnX _{2 (however,} X" which is described and X are each F, Cl, at least one selected from the group consisting of Br and I Halogen, and b and c are 0 <b ≦ 10.0 and 10 ⁻⁶ ≦ c ≦ 2 × 10 ⁻² respectively);
And bCsX ″ described in JP-A No. 61-235487.
YLn ³⁺ (where X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I, and Ln is
Sc, Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb
And at least one rare earth element selected from the group consisting of Lu, and b and y are each 0 <b ≦
10.0 and 10 ⁻⁶ ≦ y ≦ 1.8 × 10 ⁻¹ ).

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-mentioned phosphor, and may be any phosphor that exhibits stimulated emission when irradiated with excitation light after irradiation with radiation. It may be.

As described above, the stimulable phosphor and the binder are added to an appropriate solvent and mixed sufficiently to prepare a coating solution in which the stimulable phosphor is uniformly dispersed in the binder solution.

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, chlorinated polyethylene, styrene-butadiene rubber, and silicone rubber. Can be mentioned.

Among the above thermoplastic elastomers, those having a softening temperature or a melting point of 30 ° C to 300 ° C are generally used, but those having a softening temperature of 30 ° C to 200 ° C are preferable, and those having a temperature of 30 ° C to 150 ° C are preferably used. More preferred.

Examples of the solvent for preparing the coating liquid include lower alcohols such as methanol, ethanol, n-propanol and n-butanol; hydrocarbons containing chlorine atoms such as methylene chloride and ethylene chloride; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone. 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 is
Depending on the characteristics of the intended radiation image conversion panel, the type of phosphor, etc., generally, the mixing ratio of the binder and the phosphor is selected from the range of 1: 1 to 1: 100 (weight ratio), and It is particularly preferable to select from the range of 1: 8 to 1:40 (weight ratio).

The coating solution has a dispersant for improving the dispersibility of the phosphor in the coating solution, and also for improving the binding force between the binder and the phosphor in the formed phosphor layer. Various additives such as a plasticizer may be mixed. Examples of dispersants used for such purposes include:
Examples include phthalic acid, stearic acid, caproic acid, and lipophilic surfactants. Examples of plasticizers include phosphoric acid esters such as triphenyl phosphate, tricresyl phosphate, diphenyl phosphate; phthalic acid esters such as diethyl phthalate and dimethoxyethyl phthalate; ethyl phthalyl glycolate, butyl phthalyl butyl glycolate, etc. And a polyester of polyethylene glycol and a fatty acid dibasic acid, such as a polyester of triethylene glycol and adipic acid, a polyester of diethylene glycol and succinic acid, and the like.

The coating liquid 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 liquid. This coating operation can be performed by using an ordinary coating means such as a doctor blade, a roll coater or a knife coater.

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

A coating solution for forming a phosphor layer is applied onto a temporary support, dried, and then peeled from the temporary support to obtain a phosphor sheet which will 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, step b) in the method for producing a radiation image storage panel of the present invention will be described.

First, apart from the phosphor sheet formed as described above,
A support for the radiation image conversion panel is prepared. This support can be arbitrarily selected from the same material as the temporary support used when forming the phosphor sheet.

In a known radiation image conversion panel, a phosphor layer is provided in order to strengthen the bond between the support and the phosphor layer, or to improve the sensitivity or image quality (sharpness, graininess) of the radiation image conversion panel. The surface of the side support is coated with a polymer substance such as gelatin to form an adhesion-imparting layer, or a light-reflecting layer made of a light-reflecting substance such as titanium dioxide, or a light-absorbing substance made of a light absorbing substance such as carbon black. It is known to provide an absorbing layer and the like.
The support used in the present invention can also be provided with these various layers, and their configuration can be arbitrarily selected according to the desired purpose and application of the radiation image conversion panel.

Further, as described in JP-A-58-200200, the surface of the support on the phosphor layer side (the surface of the support on the phosphor layer side) 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, it means the surface thereof).

Next, the phosphor sheet obtained by step a) is subjected to a step [step b)] of laminating the phosphor sheet on a support without being adhered and fixed, and then the obtained laminate is subjected to a calender roll to soften the binder. The step [step c)] of compressing the phosphor sheet and adhering it to the support is carried out by pressing the laminate at a temperature or a temperature equal to or higher than the melting point.
The pressure treatment (compression adhesion treatment) with a calendar roll is
It is carried out by passing the above-mentioned laminated body at a constant speed between rollers heated to a softening temperature or melting point of the binder or higher.

The pressure during compression is generally 50 kgw / cm ² or more.

The porosity of the phosphor layer formed on the support as described above can be logically determined by the following formula (I).

(However, V: total volume of phosphor layer Vair: air volume in phosphor layer A: total weight of phosphor layer ρ _x : density of phosphor ρ _y : density of binder ρ air: density of air a: fluorescence Weight of body b: Weight of binder) Further, in the formula (I), since ρair is almost 0, the formula (I) can be approximately represented by the following formula (II).

(However, V, Vair, A, ρ _x , ρ _y , a, and b
In the present invention, the porosity of the phosphor layer was calculated by the formula (II).

Further, the filling rate of the phosphor can be obtained by the following formula (III).

(However, V, Vair, A, ρ _x , ρ _y , a, and b
Is the same as the formula (I).) In a normal radiation image conversion panel, the phosphor layer is physically and chemically attached to the surface of the phosphor layer opposite to the side in contact with the support as described above. A transparent protective film is provided for protection. Such a transparent protective film is preferably installed also in the radiation image storage panel according to the present invention.

The transparent protective film may be, for example, a cellulose derivative such as cellulose acetate or nitrocellulose; or a transparent polymer material such as polymethylmethacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer. It can be formed by a method in which a solution prepared by dissolving a high-molecular substance in a suitable solvent is applied to the surface of the phosphor layer. Alternatively, polyethylene terephthalate,
A plastic sheet made of polyethylene naphthalate, polyethylene, polyvinylidene chloride, polyamide, etc .; and a protective film forming sheet such as a transparent glass plate are separately formed and adhered to the surface of the phosphor layer by using an appropriate adhesive. It can also be formed by the method of.

The thickness of the protective film is generally in the range of about 0.1 to 20 μm.

Furthermore, in order to improve the sharpness of the obtained image,
An adhesive layer that absorbs excitation light but not stimulated emission light may be added to at least one of the above layers (see Japanese Examined Patent Publication No. 59-23400).

Next, examples of the present invention will be described. However, each of these examples does not limit the present invention.

[Example 1] As a coating solution for forming a phosphor sheet, phosphor: BaFBr _0.9 I _0.1 : Eu ²⁺ ...... 200 g Binder: Polyurethane (Sumitomo Bayer Urethane Co., Ltd. Desmorac TPKL-5-2525 [solid content 40%], softening temperature 45
℃) …… 22.5g Anti-yellowing agent: Epoxy resin (Yukaka Sierpoxy Co., Ltd. Epicoat 1001) …… 1.0g was added to a 1: 1 mixed solvent of methyl ethyl ketone and 2-propanol, and dispersed with a propeller mixer, Viscosity 30
A coating solution of PS (25 ° C.) was prepared (binder / phosphor ratio = 1 /
20). This was applied onto polyethylene terephthalate (temporary support, thickness 180 μm) coated with a silicone-based release agent, dried and then peeled from the temporary support to form a phosphor sheet.

On the other hand, as a coating liquid for forming the light reflecting layer, BaFBr (containing 90% of particles having a particle diameter in the range of 1 to 5 μm) ...
… 214 g Soft acrylic resin solid content …… 25.7 g Epoxy resin …… 10.7 g Nitrocellulose (nitrification degree 11.5%, solid content 10% by weight)…
64 g was added to methyl ethyl ketone and dispersed by a propeller mixer to prepare a dispersion liquid having a viscosity of 25 to 35 PS (25 ° C.).

Separately, as a coating liquid for forming an undercoat layer, soft acrylic resin solid content ...... 90 g nitrocellulose ...... 50 g is added to methyl ethyl ketone, dispersed and mixed to give a viscosity of 3
A dispersion of ~ 6PS (25 ° C) was prepared.

A 300 μm thick polyethylene terephthalate (support) is placed horizontally on a glass plate, and the above undercoat layer forming coating solution is uniformly applied on the support using a doctor blade, and then gradually from 25 ° C to 100 ° C. The coating film was dried by elevating the temperature to form an undercoat layer on the support (coating film thickness: 15 μm). Further, the above-mentioned coating solution for forming a light reflection layer was applied (thickness of the coating film: 60 μm), and dried similarly to form an undercoat layer and a light reflection layer on the support. The phosphor sheet prepared first was placed on this, and compression was performed.

The compression was continuously performed using a calender roll at a pressure of 400 Kgw / cm ² and a temperature of 80 ° C. With this compression,
The phosphor sheet and the light-reflecting layer on the support were completely fused.

After this compression, a transparent protective film was formed by adhering a transparent polyethylene terephthalate film (thickness 10 μm) coated with a polyester adhesive on one side with the adhesive side facing down.

As described above, a radiation image conversion panel composed of the support, the undercoat layer, the light reflection layer, the phosphor layer, and the transparent protective film was manufactured.

Example 2 In the same manner as in Example 1 except that the pressure at the time of compression was 600 KgW / cm ² , the support, the undercoat layer, the light reflection layer, the phosphor layer, and the transparent protective film were formed. A constructed radiation image conversion panel was produced.

Example 3 In the same manner as in Example 1 except that the pressure at the time of compression was 800 KgW / cm ² , the support, the undercoat layer, the light reflection layer, the phosphor layer, and the transparent protective film were formed. A constructed radiation image conversion panel was produced.

[Comparative Example 1] After forming an undercoat layer in the same manner as in Example 1, a coating liquid for forming a reflective layer was applied, and before the coating film was dried,
The phosphor layer-forming coating liquid was subsequently applied thereon. The temperature was gradually raised from 25 ° C. to 100 ° C. and drying was performed to form a sheet comprising a support, an undercoat layer, a light reflection layer, and a phosphor layer. Next, this sheet was compressed using a calender roll in the same manner as in Example 1 at a pressure of 400 Kg / cm ² and a temperature of 80 ° C. Further, a protective film was provided by the same method as in Example 1, and the support, the undercoat layer, the light reflection layer, the phosphor layer,
A radiation image conversion panel composed of a transparent protective film was manufactured.

[Comparative Example 2] In Comparative Example 1, the support, undercoat layer, light reflecting layer, phosphor layer, and transparent protective film were prepared in the same manner as in Comparative Example 1 except that the pressure during compression was 600 Kgw / cm ^2. A constructed radiation image conversion panel was produced.

[Comparative Example 3] In Comparative Example 1, the support, undercoat layer, light reflecting layer, phosphor layer, and transparent protective film were formed in the same manner as in Comparative Example 1 except that the pressure during compression was 800 Kgw / cm ^2. A constructed radiation image conversion panel was produced.

[Comparative Example 4] In Comparative Example 1, a radiation image conversion comprising a support, an undercoat layer, a light reflecting layer, a phosphor layer and a transparent protective film was carried out in the same manner as in Comparative Example 1 except that no compression was carried out. The panel was manufactured.

Phosphor filling rate and porosity of the radiation image conversion panel phosphor layer In the phosphor layer of each of the radiation image conversion panels of Examples and Comparative Examples produced as described above, the phosphor filling rate and the porosity are defined as (II ) And equation (III).
However, the density of the phosphor is 5.1 g / cm ³ and the density of the binder is 1.
It is 14 g / cm ³ .

 The results are shown in Table 1.

As is clear from Table 1, the radiation image storage panel manufactured according to the present invention has a higher phosphor packing rate and a higher porosity than the panel manufactured by the conventional manufacturing method, which is compressed under the same pressure. It turns out that it has been lowered.

Evaluation of Image Quality of Radiation Image Conversion Panel The image quality of each radiation image conversion panel manufactured as described above was evaluated by the method described below. That is, the radiation image conversion panel is irradiated with X-rays with a tube voltage of 80 KVp, then scanned with He-Ne laser light (632.8 nm) to excite the phosphor, and the stimulated emission emitted from the phosphor layer is received. Then, it was converted into an electric signal, which was reproduced as an image by the image reproducing device to obtain an image on the display device. Modulation transfer function (MTF) of the obtained image (air conditioning frequency: 2 cycles /
mm), and the granularity (RMS) at a dose of 0.1 mR was measured.

 The obtained results are shown together in the form of a graph in FIG.

Figure 1 shows the vertical axis with sharpness (spatial frequency 2 cycles / m
The MTF value at m) is taken, and the higher the plot, the higher the sharpness. The horizontal axis indicates the graininess, and the more plotted to the left, the better the graininess.

As is apparent from FIG. 1, the radiation image conversion panel manufactured according to the present invention has a sharpness as compared with a panel manufactured by the conventional manufacturing method, which is compressed under the same pressure.
It can be seen that the grain size is slightly improved, and the graininess is greatly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the image quality of radiation image conversion panels according to Examples and Comparative Examples.

Claims (1)

(57) [Claims] 1. A method for producing a radiation image conversion panel, which is essentially composed of a support, and a phosphor layer comprising a binder and a stimulable phosphor provided on the support, which comprises: a. ) A step of forming a phosphor sheet composed of a binder and a stimulable phosphor, b) a step of laminating the phosphor sheet on a support without adhering and fixing it, and c) a calendar of the obtained laminate. A step of pressing the laminate at a softening temperature of the binder or at a temperature equal to or higher than the melting point of the binder, thereby compressing the phosphor sheet and adhering it to the support; Manufacturing method.