JPH0261599A - Manufacture of radiation image transformation panel - Google Patents

Abstract

PURPOSE:To sinter without the unevenness of quality by sintering two or more sheet-like formed phosphor layer formation material on condition that they are laminated through a ceramic paper substantially containing no organic substances. CONSTITUTION:Powder-like material composed of particles of accelerated phosphor is used as phosphor layer formation material. Further a dispersion containing the particles of accelerated phosphor and bonding agent can be used. Next, powder-like material composed of the phosphor particles prepared or the dispersion containing the phosphor and the bonding agent is formed in the form of a sheet. In the case where the phosphor layer formation material is powder-like material for forming, the powder-like material is pushed in a forming mold to form. In the case where the phosphor layer formation material is the dispersion, the dispersion is applied to a proper board to form it or make it flow in the forming mold to form it. Next, obtained sheet-like forming material is sintered. A ceramic paper is sandwiched to laminate many sheet-like formed materials, which are sintered by a burning treatment at one time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] 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.

[Technical Background of the Invention and Prior Art] As an alternative to conventional radiography, there is a radiation image conversion method using a stimulable phosphor as described in, for example, Japanese Unexamined Patent Publication No. 55-12145. Are known.

This method uses a radiation image conversion panel (also called a stimulable phosphor sheet) containing a photostimulable phosphor, and converts the radiation transmitted through or emitted from the object into a radiation image conversion panel containing a photostimulable phosphor. The stimulable phosphor is absorbed by the phosphor, and then exposed to electromagnetic waves (excitation light) such as visible light and infrared rays.
By excitation in a time series with
This fluorescence is photoelectrically read to obtain an electrical signal, and based on the obtained electrical signal, a radiation image of the subject or subject is reproduced as a visible image.

According to this radiation image conversion method, it is possible to obtain a radiation image with a rich amount of information with a much lower exposure dose compared to the conventional radiography method that uses a combination of a radiographic film and an intensifying screen. It has the advantage of being possible. Therefore, this method has a very high utility value especially in direct medical radiography such as x*m shadows for the purpose of medical diagnosis.

The radiation image conversion panel used in the radiation image conversion method is
The basic structure consists of a support and a stimulable phosphor layer provided on one side of the support.

Note that a support is not necessarily required when the phosphor layer is self-supporting. Also, the surface of this stimulable phosphor layer opposite to the support (the surface not facing the support)
Generally, a transparent protective film is provided to protect the phosphor layer from chemical alteration or physical impact.

A stimulable phosphor layer generally consists of a stimulable phosphor and a binder that contains and supports the stimulable phosphor in a dispersed state.The stimulable phosphor absorbs radiation such as X-rays and then absorbs excitation light. It has the property of exhibiting stimulated luminescence when irradiated. 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 displayed on the panel. It is formed as an image of accumulated energy. This accumulated image can be emitted as stimulated luminescence light by irradiating the excitation light, and by photoelectrically reading this stimulated luminescence light and converting it into an electrical signal, the accumulated image of radiation energy can be visualized. It becomes possible to do so.

The radiation image conversion method is a very advantageous image forming method as mentioned above, but the radiation image conversion panel used in this method is similar to the intensifying screen used in conventional radiography.
It is desired that the image quality is high and provides an image with good image quality (sharpness, graininess, etc.).

The sensitivity of a radiation image conversion panel basically depends on the total amount of stimulated luminescence of the stimulable phosphors contained in the panel, and this total amount of luminescence depends not only on the luminance of the phosphors themselves but also on the fluorescence It also varies depending on the content of phosphor in the body layer. A high content of phosphor also means high absorption of radiation such as X-rays, resulting in higher sensitivity and at the same time improved image quality (particularly graininess). On the other hand, if the phosphor content in the phosphor layer is constant,
The denser the phosphor particles are packed, the thinner the layer thickness can be, so the spread of excitation light due to scattering can be reduced, and relatively high sharpness can be obtained.

Up until now, the phosphor layer has generally been formed by preparing a coating solution in which stimulable phosphor particles are dispersed in a binder solution, and applying this coating solution using a conventional coating method such as a doctor blade or roll coater. This is done by applying the coating onto a support or another sheet and then drying it. In the radiation image storage panel formed in this way, which has a phosphor layer in which phosphor particles are dispersed in a binder, there are limits to the content and packing density of the phosphor in the phosphor layer. It was difficult to obtain sufficiently satisfactory sensitivity and image quality.

For this reason, a radiation image conversion panel has been proposed that has a phosphor layer in which phosphor particles are not dispersed in a binder, but in which phosphors form aggregates.

As a method for forming a phosphor layer consisting only of a stimulable phosphor without containing a binder, for example, US Pat.
No. 59,527 describes that the storage medium is composed of a phosphor obtained by a hot pressing method, and JP-A-61-73100 describes that a phosphor layer is formed using a baking method. A method for forming the is described.

The applicant has proposed a radiation image conversion panel having a support and a phosphor layer made of a stimulable phosphor provided on the support, in which the phosphor layer is sintered. We have already filed a patent application for a radiation image conversion panel, which is characterized by being made of human body, and a method for manufacturing the same.

(Japanese Unexamined Patent Publication No. 19600/1983, Patent Application No. 167/1983
No. 630) Furthermore, the applicant has proposed that the phosphor layer is made of a sintered stimulable phosphor or a vapor-deposited stimulable phosphor, and that the phosphor layer is impregnated with a polymeric substance. A patent application has already been filed for a radiation image conversion panel and its manufacturing method (Japanese Patent Application No. 62-96803).

In these phosphor layers, the phosphor particles are not dispersed but aggregated. That is, these phosphor layers either do not contain any polymeric material, or even if they do, the polymeric material is impregnated into the phosphor layer, and the polymeric material is an aggregate of phosphor. It exists in gaps (for example, in the case of a sintered phosphor layer, in the grain boundaries and/or pores of the phosphor).

As mentioned above, a phosphor layer made of aggregates of stimulable phosphors can be manufactured by a sintering method, a vapor deposition method, or the like. In other words, even if the phosphor layer contains a polymeric substance, a phosphor layer that does not contain any polymeric substance at all is created by a sintering method or vapor deposition method, and then the phosphor layer is impregnated with the polymeric substance. It can be manufactured by

When manufacturing a sintered phosphor layer made of aggregates of stimulable phosphor as described above by a sintering method, the manufacturing process is as follows:
The method consists of the following steps:) forming a phosphor layer-forming material containing a stimulable phosphor into a sheet shape; and ii) firing the molded product to sinter the phosphor. Among these, step i) above involves filling a mold with powdered phosphor and molding it under pressure, or dispersing or suspending the phosphor in a solvent together with a binder, dispersant, etc. This is carried out by preparing a coating liquid, applying this coating liquid to a substrate to form a phosphor film, and then decomposing or evaporating the binder, dispersant, etc. by heating.

On the other hand, in step ii) above, the molded product is placed in a furnace,
This is done by firing in a neutral or reducing atmosphere. At this time, it is desired to sinter a large number of molded products at the same time with uniform quality in one firing process (batch) in order to reduce manufacturing costs. However, simply arranging the molded products in a two-dimensional manner does not allow sufficient use of the space inside the furnace, making it impossible to reduce manufacturing costs. Furthermore, if the molded products are simply stacked together and then fired, there is a risk that the molded products will bond together due to sintering, and the overlapping parts of the molded products will not be able to fully react during firing through the gas phase. Since this is not done, the overlapping portion (the plane of the molded product, that is, the portion that becomes the light-receiving surface of the phosphor layer) is not sufficiently fired, resulting in decreased sensitivity and uneven quality.

[Summary of the Invention] An object of the present invention is to provide a method for manufacturing a radiation image conversion panel that can simultaneously sinter a large number of phosphor layer-forming material molded products with uniform quality in -times of firing treatment. It is something to do.

The above object is to form two or more sheet-shaped phosphor layers in the method of manufacturing a radiation image conversion panel having a sintered phosphor layer made of aggregates of stimulable phosphors according to the present invention. This can be achieved by a method for manufacturing a radiation image storage panel characterized in that a phosphor layer is formed by sintering materials in a laminated state with ceramic paper that does not substantially contain organic matter interposed therebetween.

The above-mentioned sintered phosphor layer also includes a phosphor layer formed by sintering and then impregnated with a polymeric substance.

The ceramic paper (T#, also referred to as machine fiber paper) used in the present invention is a sheet formed from an aggregate of ceramic fibers whose main components are aluminum oxide, silicon dioxide, etc., as will be described in detail later. .

According to the method for manufacturing a radiation image conversion panel of the present invention, a large number of the molded articles can be arranged with ceramic papers sandwiched therebetween depending on the number of sheets of ceramic paper used, so that the space in the furnace can be sufficiently saved. Not only can it be used, but the molded products will not be sintered and bonded together.

Furthermore, since ceramic paper is porous, reactions occur through the gas phase even in the areas where the molded product and the ceramic paper overlap, so that there is no reduction in sensitivity or unevenness in quality.

Preferred embodiments of the present invention are listed below.

(1) Alternately stacking the sheet-shaped phosphor layer forming material and the ceramic paper in the vertical direction;
A method for producing a radiation image conversion panel, which comprises firing.

(2) Alternately stacking the sheet-shaped phosphor layer forming material and the ceramic paper in a horizontal direction;
A method for producing a radiation image conversion panel, which comprises sandwiching and firing the panel.

(3) The phosphor layer forming material formed into the sheet shape is
A method for producing a radiation image conversion panel comprising only a stimulable phosphor.

(4) A method for producing a radiation image conversion panel, wherein the stimulable phosphor is a divalent europium-activated alkaline earth metal halide phosphor.

(5) A method for producing a radiation image storage panel, wherein the ceramic paper is heat-treated in a temperature range of 300°C to 650°C in a neutral or oxidizing atmosphere.

(6) A method for manufacturing a radiation image conversion panel, characterized in that the heat treatment is performed while the ceramic paper and the sheet-shaped phosphor layer forming material are alternately laminated.

(7) The above sintering was carried out for 50 minutes in a neutral or reducing atmosphere.
A method for manufacturing a radiation image conversion panel, characterized in that the manufacturing method is carried out at a temperature range of 0°C to 1000°C.

(8) The sintering is carried out for 70 minutes in a neutral or reducing atmosphere.
A method for manufacturing a radiation image conversion panel, characterized in that the manufacturing method is carried out at a temperature range of 0°C to 950°C.

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

First, the stimulable phosphor will be described.

Hereinafter, a margin photostimulable phosphor is a phosphor that exhibits stimulated luminescence when irradiated with radiation and then irradiated with excitation light, as described above.
From a practical standpoint, a phosphor that exhibits stimulated luminescence in a wavelength range of 300 to 500 nm by excitation light in a wavelength range of 400 to 900 nm is desirable. Examples of stimulable phosphors used in the method of manufacturing the radiation image storage panel of the present invention include SrS:Ce, Sm, and SrS:Eu, which are described in US Pat. No. 3,859,527.

Sm, Th02:Er, and La2O2S:Eu,
Sm.

ZnS described in Japanese Patent Application Laid-Open No. 55-12142
:Cu, Pb%Ba0-xAl2O3:Eu (however,
0.8≦X≦10), and M”0−xsic12
:A (However, M! is Mg, Ca, Sr, Zn, Cd
, or Ba, where A is Ce, Tb, Eu, Tm%P
b, TIL, Bi.

or Mn, and X is 0.5≦X≦2.5)
, described in Japanese Patent Application Laid-Open No. 55-12143 (B
a+-! −F 9Mg I + CaF ) F
X “aEu” (where, X is at least one of C1 and Br, and X and y are O< x +
y≦0.6 and xy≠0, and a is 1o-6≦a
≦5xlO-2), LnO described in JP-A-55-12144
X: xA (Ln is La, Y.

At least one of Gd and Lu, X is at least one of C1 and Br, A is Ce and Tb
and X is 0<x<0.
1), described in JP-A-55-12145 (B
a 1- II I M ” x ) F X:
yA (However, M 2+ is Mg, Ca, Sr, Zn,
and Cd, X is CIL, Br
, and at least one of ■, A is Eu, Tb,
At least one of Ce, Tm%Dy1Pr, Ho, Nd, Yb, and E, and X is 0≦X
≦0.6, y is 0≦y≦0.2), M” described in JP-A-55-160078.
FX-xA:yLn [However, Ml is Ba%Ca%Sr
, Mg%Zn, and at least one of Cd, A
is Bed, MgO, CaO1SrO, BaO1ZnO1
AJ! ,O,,Y2O3,La2O3,In2O2,5
i02, TiO2, ZrO2, GeO2, 5n02, N
b.

05, Ta2O@, and at least one of ThO2, Ln is Eu%Tb%Ce, TmlDy%Pr,
Ho% At least one of Nd, Yb, Er, Sm, and Gd, X is at least one of CJ2, Br, and ■, and X and y are each 5×
10-s≦X≦0.5, and o<y≦0.2]
The phosphor represented by the composition formula is
a+-1,M”X)F2 ・aBaX2 :yEu,
zA [However, Ml 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 zirconium and scandium. , a, x, y, and 2 are respectively 0.5≦a≦1.25, O≦X≦1.
10-'≦y≦2X10-', and O<z≦10-2
A phosphor represented by the composition formula, JP-A-57-2
3673 (Ba+-in M”
x) F2 ・aBaX2 :yEu, zB [However, MI 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 2 are each 0.5
≦a≦1.25, O≦X≦1.10-”≦y≦2×10
-゛, and O<z≦2×10-''], which is described in Japanese Patent Application Laid-open No. 57-23675 (B
a, -1, M-tension x) F2 ・aBaX2 : yEu, z
A [However, Mx 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. , a, x, y, and 2 are each 0
．． 5≦a≦1.25.0≦X≦1.10-6≦y≦2×
to-', and O<z≦5X10-';
X: xCe [However, Ml is Pr, NdPm%S
m, Eu, Tb, Dy, Ho, Er.

Tm% Yb, and at least one trivalent metal selected from the group consisting of Bi, X is one or both of C1 and Br, and X is O<x<
A phosphor represented by the composition formula of
a r-z M I /2 L! /2 F
: y E u ” [However, M is Li, Na,
Represents at least one alkali metal selected from the group consisting of Rb% and Cs; L is Sc, Y, La, C
e, Pr, Nd% Pm% Sm, Gd, Tb,
Dy.

Ho, Er% Tm% Yb, Lu% An,
Ga.

represents at least one trivalent metal selected from the group consisting of In and Tu; X represents at least one halogen selected from the group consisting of C1, Br, and ■; and X represents 10-2≦X ≦0.5, y is o<y≦
A phosphor represented by the composition formula of
X −xA: yEu” [However, X is C1, B
r, and at least one halogen selected from the group consisting of summer; A is a fired product of a tetrafluoroboric acid compound; and X is 10-6≦X≦0.1, y
is a phosphor represented by the composition formula: o<y≦0.1], described in JP-A-59-47289,
FX −xA: yEu” [However, X is C1,
Br, and at least one halogen selected from the group consisting of; A is from the hexafluoro compound group consisting of monovalent or divalent metal salts of hexafluorosilicic acid, hexafluorotitanic acid, and hexafluorozirconic acid; It is a baked product of at least one selected compound: and X is 10-6≦X≦0.1, and y is o<
y≦0.1], a phosphor represented by the composition formula BaFX-
xNaX':aEu'' [where X and Xo are at least one of C1%Br and I, respectively, and X and a are 0<x≦2 and 0<a≦
A phosphor represented by the composition formula:
FX −xNaX′:yEu”: zA [However, M
l is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca;
o is at least one kind of halogen selected from the group consisting of C2, Br, and ■; A is V, C
r, Mn.

is at least one transition metal selected from Fe, COl and Ni; and X is O<x≦2, y is 0<y
≦0.2, and 2 is 0<z≦10-2.
bM'"X"2・cM"X"2・xA: y
Eu'' [However, MI is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; MI is at least one kind selected from the group consisting of Li%Na, Rb, and Cs. is an alkali metal; Mol is at least one divalent metal selected from the group consisting of Be and Mg; B411 is A2, Ga
, In, and TJZ; A is a metal oxide; X is at least one halogen selected from the group consisting of C1, Br, and ■ Q; X'x" and X"
° is F, Cl3. , Br, and at least one kind of halogen selected from the group consisting of I; and a
is 0≦a≦2, b is 0≦b≦10-'c is 0≦C≦10
-2 and a+b+c≧1O−6: X is O<x≦0
．． 5, y is 0<y≦0.2] A phosphor represented by the composition formula M” described in JP-A-60-84381.
X2- aM"
o is at least one kind of halogen selected from the group consisting of C2, Br, and summer, and X#X'; and a is 0.1≦a≦10.0, and X is O<x≦0. A stimulable phosphor represented by the composition formula:
FX-aM'X':xEu"" [However, Ml is B
Ml is at least one alkaline earth metal selected from the group consisting of a, Sr and Ca; Ml is Rb and Cs
is at least one kind of alkali metal selected from the group consisting of: X is at least one kind of halogen selected from the group consisting of C1, Br and ■: x° is F, Cl
3, at least one kind of halogen selected from the group consisting of Br and ■: and a and X are each 0≦
A stimulable phosphor represented by the following composition formula where a≦4.0 and O<x≦0.2, M'X described in JP-A No. 62-25189
:xBi [where Ml is at least one alkali metal selected from the group consisting of RbS and C3:
X is at least one kind of halogen selected from the group consisting of Cl2, Br and I; and X is 0<x≦0.
Examples include a stimulable phosphor represented by the composition formula:

Furthermore, M"
The following additives are mixed into the stimulable phosphor.
It may be contained in the following proportions per mole of 2.aM"X'2.

bM described in JP-A-60-166379
Ix゛ (However, Ml is at least one kind of alkali metal selected from the group consisting of Rbi and Cs, and X''
is at least one kind of halogen selected from the group consisting of F, C1t, Br and ■, and b is o<b≦1
0.0); described in Japanese Patent Application Laid-Open No. 60-221483.
M”X-”! (Tatashi, M seal is Sc, Y, La%
is at least one kind of trivalent metal selected from the group consisting of Gd and Lu; , c and d are respectively 0≦b≦2.0.0≦C≦2.0.0≦d≦
2.0 and 2 x 10-'≦b+c+d): yB described in JP-A-60-228592 (however, y is 2x I Q-'≦y≦2X1
0-'); bA described in JP-A No. 60-228593 (However, A is 5i02 and P2O
at least one oxide selected from the group consisting of 5, where b is 10-4≦b≦2X10'')
bS described in Japanese Patent Application Laid-Open No. 61-120883
in (however, b is o<b≦3 x 10-”)
; Described in Japanese Patent Application Laid-open No. 120885/19866
bSnX・"2 (where x" is at least one kind of halogen selected from the group consisting of FlCIL, Br and I, and b is o<bSin-3); described in JP-A-61-235486 bCsX″
・cSnX"°2 (where x" and x" are at least one kind of halogen selected from the group consisting of tLF, CIL, Br and ≦10.0 and 10-6≦C≦
2×10-2); and JP-A-61-23548
bCsX”・y L n ” described in the 7-ship bulletin
(However, X'' is at least one kind of halogen selected from the group consisting of F, CIL, Br and I, and Ln is Sc, Y, Ce, Pr% Nd, Sm.

Gd, Tb, Dy, Ho, Er%Tm, Yb and Lu
at least one rare earth element selected from the group consisting of, and b and y each satisfy o<b≦10.0.
and 10-6≦y≦1.8X 10-').

Among the above-mentioned stimulable phosphors, divalent europium-activated alkaline earth metal halide phosphors are particularly preferred because they exhibit high-intensity stimulated luminescence. However, the stimulable phosphor used in the present invention is not limited to the above-mentioned phosphors, and any phosphor that exhibits stimulated luminescence when irradiated with radiation and then irradiated with excitation light can be used. There may be.

Remains 1" The phosphor layer can be formed, for example, by the following manufacturing process.

That is, the manufacturing process of the phosphor layer consists of a step of molding a phosphor layer forming material containing a stimulable phosphor into a sheet shape, and a step of sintering this molded product.

In the process of forming the phosphor layer forming material into a sheet shape,
As the material for forming the phosphor layer, a powder made of particles of the above-mentioned stimulable phosphor can be used.

Moreover, a dispersion containing particles of the above-mentioned stimulable phosphor and a binder can also be used as the material for forming the phosphor layer. In this case, the stimulable phosphor and binder are added to a suitable solvent and then thoroughly mixed to prepare a dispersion in which phosphor particles are uniformly dispersed in the binder solution.

As the binder, it is preferable to use a substance that has suitable properties in terms of the dispersibility of the phosphor, or the divergence in the debonding process performed by heat treatment prior to sintering. Examples of this include paraffin (e.g., carbon number: 16 to 4)
0, melting point: 37.8 to 64.5°C): Wax (natural waxes include: candelilla wax, carnauba wax, rice wax, vegetable waxes such as wood wax, beeswax, lanolin, spermaceti wax, etc.) Animal waxes, montan wax, mineral waxes such as ozokerite ceresin, and synthetic waxes include: coal-based synthetic waxes such as polyethylene wax and Fischer-Tropsch wax.

Hardened and oil-based synthetic waxes such as mustard oil, fatty acid amides, and ketones) Niresin (polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, vinylidene chloride/vinyl chloride copolymer, polyalkyl (meth)acrylate, vinyl chloride/vinyl acetate copolymer,
(polyurethane cellulose acetate butyrate, polyvinyl alcohol, linear polyester), etc. Proteins such as gelatin, polysaccharides such as dextran, or gum arabic can also be used.

Examples of solvents include lower alcohols such as methanol, ethanol, n-propanol, and n-butanol; chlorine-containing hydrocarbons such as methylene chloride and ethylene chloride; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; methyl acetate; Esters of lower fatty acids and lower alcohols such as ethyl acetate and butyl acetate; ethers such as dioxane, ethylene glycol monoethyl ether, and ethylene glycol monomethyl ether; and mixtures thereof.

The mixing ratio of the binder and the stimulable phosphor in the above dispersion varies depending on the type of phosphor and the molding conditions and sintering conditions described below, but generally the mixing ratio of the binder and the stimulable phosphor is 1: 1 to 1:300 (weight ratio), and particularly preferably from 1:20 to 1:150 (weight ratio).

Note that the dispersion liquid may contain additives such as a dispersant for improving the dispersibility of the phosphor. Examples of dispersants used for such purposes include phthalic acid, stearic acid, caproic acid, lipophilic surfactants, and the like.

The powder made of the phosphor particles prepared as described above or the dispersion containing the phosphor particles and a binder is then formed into a sheet.

When the material for forming the phosphor layer is a powder, it is preferable to press the powder into a mold to form a sheet. A rectangular mold is usually used for molding. In addition, when the phosphor layer forming material is a dispersion liquid, the usual coating method (for example, doctor blade, etc.)
It is preferable to apply the powder onto a suitable substrate and form it into a sheet, or to form it into a sheet by pouring it into a mold in the same way as the powder.

When the material for forming the phosphor layer is a dispersion containing a stimulable phosphor and a binder, a binder process is performed. This process is
The binder in the dispersion liquid is heated at a relatively low temperature (100%
-450°C). Due to the diffusion of the binder in this low temperature range, components other than the stimulable phosphor, such as the binder, volatilize or carbonize at around 300 to 400°C, and further become carbon dioxide, which can be easily removed. Preferably, the time for cold aeration is in the range of 0.5 to 6 hours.

When molded on a substrate by coating, the molded product is peeled off from the substrate after this heat treatment to obtain a sheet-like molded product composed only of the stimulable phosphor.

In the above molding step, compression treatment may be performed,
Sometimes, when the material for forming the phosphor layer is a powder, compression treatment is performed. The compression treatment is carried out, for example, by press molding, and is preferably carried out by applying a pressure in the range of 1 x 102 to 1 x 10'kg/crn'. This makes it possible to further increase the relative density of the resulting phosphor layer.

Next, the sheet-like molded product obtained as described above is sintered.

The present invention is characterized in that a large number of sheet-shaped molded products are stacked with ceramic paper sandwiched between them, and the large number of molded products are simultaneously sintered in one firing process (batch).

Ceramic paper is also called inorganic fiber paper and is made of aluminum oxide (AI1203), silicon dioxide (Sin,
) is formed into a sheet from an aggregate of ceramic fibers whose main components are This ceramic paper is
It is produced by dispersing ceramic fibers in water, using essentially the same method used to produce regular paper in a paper machine.

Therefore, it is essentially porous and has high heat resistance.

However, since ceramic fibers do not have the entanglement characteristic of cellulose fibers, they cannot be made into a sheet using only ceramic fibers. Therefore, an organic component is usually contained as a binder.

This organic component carbonizes during firing and blackens the molded product, resulting in a decrease in the sensitivity of the manufactured radiation image storage panel. 19 Therefore, the ceramic paper used in the present invention is
It is necessary to remove organic components before sintering the phosphor. For example, in a neutral or oxidizing atmosphere,
By heat-treating in the temperature range of .degree. C. to 650.degree. C., ceramic paper substantially free of organic matter can be obtained. This heat treatment may be performed in advance before laminating the ceramic paper and the sheet-like molded product described above, or may be performed in the laminated state before sintering the phosphor, but This is preferable because it does not deteriorate the phosphor.

In addition, when obtaining a sheet-like molded product from a dispersion containing a stimulable phosphor and a binder, as mentioned above, a step is required to diffuse components other than the stimulable phosphor, such as the binder. However, it is preferable that this step be carried out in advance before laminating with ceramic paper in between, and that the molded article is composed only of the stimulable phosphor in the laminating step.

The arrangement of the sheet-like molded product and the ceramic paper is as shown in FIG. 1, for example. In FIG. 1, sheet-shaped phosphor layer forming material 1a and ceramic paper 2a are alternately stacked vertically on a heat-resistant plate 3. The heat-resistant plate 3 can be made of, for example, a quartz plate. Further, a heat-resistant material may be further placed on the top surface of the laminate of the molded product and ceramic paper as a weight.

FIG. 2 shows another example of the arrangement of the sheet-like molded product and the ceramic paper. In FIG. 2, a sheet-like molded product 1b and a ceramic paper 2b are stacked horizontally and held by a holding tool 4.

In the above state, the phosphor layer forming material is sintered.

Sintering is performed, for example, in a firing furnace such as an electric furnace. The sintering temperature and sintering time vary depending on the type of phosphor layer forming material, the shape and condition of the sheet-shaped molded product, and the type of stimulable phosphor used therein, but in general, the sintering temperature is 500°C. The temperature is in the range of 1000°C to 1000°C, preferably 7
The temperature range is from 00 to 950°C. Further, the sintering time is generally in the range of 0.5 to 6 hours, preferably in the range of 1.5 to 2 hours. The sintering atmosphere is usually a nitrogen gas atmosphere, a neutral gas atmosphere such as an argon gas atmosphere, a nitrogen gas atmosphere containing a small amount of hydrogen gas, or a -
A weakly reducing atmosphere such as a carbon monoxide atmosphere containing carbon oxides is used.

Note that the compression treatment may be performed during the sintering process as described above, but it may also be performed during the sintering process. That is,
Sintering may be performed while performing compression treatment.

The thickness of the phosphor layer formed in this manner varies depending on the characteristics of the intended radiation image conversion panel, but is usually 20 μm to 1 mm.

However, the thickness of this layer is preferably 50 to 500 μm.

The phosphor layer formed by the above method is further coated with the following materials to provide strength against physical impact and environmental changes.
It may also be impregnated with a polymeric substance.

Next, a support is provided on one surface of the formed phosphor layer.

The support used in the present invention can be arbitrarily selected from various materials used as supports for intensifying screens in conventional radiography methods or materials known as supports for radiation image conversion panels. . Examples of such materials include cellulose acetate, polyester,
Films of plastic materials such as polyethylene terephthalate, polyamide, polyimide, triacetate, polycarbonate, metal sheets such as aluminum foil, aluminum alloy foil, ceramic plates such as alumina, zirconia, magnesia, titania, ordinary paper, baryta paper, resin coating. Examples include paper, pigment paper containing pigments such as titanium dioxide, and paper sized with polyvinyl alcohol. When a plastic film is used, a light-absorbing substance such as carbon black may be kneaded into it, or a light-reflecting substance such as titanium dioxide may be kneaded into it. The former is a support suitable for a high sharpness type radiation image conversion panel, and the latter is a support suitable for a high sensitivity type radiation image conversion panel.

In known radiation image conversion panels, 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, granularity) of the radiation image conversion panel. A polymeric substance such as gelatin is coated on the surface of the support on the side to be coated to form an adhesion imparting layer, or a light reflective layer made of a light reflective substance such as titanium dioxide, or a light absorbing substance such as carbon black. Providing a light absorption layer is also practiced. The support used in the present invention can also be provided with these various layers.

Furthermore, as described in JP-A No. 58-200200, in order to improve the sharpness of images, adhesives are added to the surface of the support on the phosphor layer side (the surface of the support on the phosphor layer side). When an imparting layer, a light reflecting layer, a light absorbing layer, etc. are provided, fine irregularities may be uniformly formed on the surface (meaning the surface thereof).

Attachment of the support to the phosphor layer is carried out by applying a generally used adhesive to one side of the support and then pressing one side of the phosphor layer onto that surface.

It is preferable that a transparent protective film be provided on the surface of the phosphor layer opposite to the side in contact with the support for the purpose of physically and chemically protecting the phosphor layer.

The transparent protective film may be made of, for example, a cellulose derivative such as cellulose acetate or nitrocellulose; or a synthetic polymeric material such as polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, or vinyl chloride/vinyl acetate copolymer. It can be formed by applying a solution prepared by dissolving a transparent polymer substance in a suitable solvent onto the phosphor layer. Alternatively, a plastic sheet made of polyethylene terephthalate, polyethylene, polyvinylidene chloride, polyamide, etc. and a protective film forming sheet such as a transparent glass plate are formed separately and adhered to the surface of the phosphor layer using an appropriate adhesive. It can also be formed by the following method. The thickness of the transparent protective film thus formed is preferably about 3 to 20 μm.

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

[Example 1] Methyl ethyl ketone was added to a mixture of powdered divalent europium-activated barium fluoride bromide phosphor particles (BaFBr: 0.001Eu") and an acrylic resin to contain the phosphor particles in a dispersed state. Next, this dispersion was sufficiently stirred and mixed using a propeller mixer to ensure that the phosphor particles were uniformly dispersed and that the mixing ratio of the binder and the phosphor particles was 1:20. (weight ratio), viscosity is 35-50
A coating solution of Ps (25° C.) was prepared.

Next, the obtained coating solution was uniformly applied onto a horizontally placed Teflon sheet using a doctor blade. After coating, the Teflon sheet on which the coating film was formed was placed in a dryer, and the temperature inside the dryer was gradually raised from 25° C. to 100° C. to dry the coating film. After drying, the coating film (thickness: 350 μm) was peeled off from the Teflon sheet, placed on a quartz plate, and placed in an electric furnace for 1 hour at 400°C in an air atmosphere to diffuse the binder and sinter. A sheet-like molded product was obtained.

Next, ceramic vapor (MC paper manufactured by Nippon Inuki ■) was heat treated in air at 600° C. for 2 hours to remove organic components.

Twenty sheets of the sheet-like molded product obtained as described above and the heat-treated ceramic vapor were stacked alternately on a quartz plate, and a quartz plate was further placed on top.

The laminate of this sheet-like molded product and ceramic vapor was placed in an electric furnace to sinter the phosphor.

Sintering was performed at a temperature of 800° C. for 2 hours in a nitrogen gas atmosphere. The obtained sintered product was taken out of the electric furnace and cooled to form 20 phosphor layers each consisting of only phosphor and having a layer thickness of 300 μm.

A support was attached to one side of each of the obtained phosphor layers by adhering it to a carbon black-mixed polyethylene terephthalate sheet (support, thickness = 250 μm) using a polyester adhesive.

Furthermore, on the other side of the phosphor layer (opposite to the support), a transparent film of polyethylene terephthalate (thickness: 12 μm, coated with a polyester adhesive) was placed with the adhesive layer side facing down. By placing and adhering, a transparent protective film was formed.

In this way, 20 radiation image conversion panels each consisting of a support, a phosphor layer, and a transparent protective film were manufactured in this order.

- Panel 1 The 20 radiation image conversion panels produced as described above were evaluated by performing a sensitivity test.

In the sensitivity test, 20 radiation image conversion panels were numbered N011 to No. 20 in the order of stacking during firing, and after irradiating each panel with X-rays with a tube voltage of 5 oicvp, He-Ne The sensitivity was measured by excitation with laser light.

The results are shown in Table 1.

The conversion panels in Table 1 (No. 1 to No. 20) have small variations in sensitivity. Therefore, from this example, it is clear that the method for manufacturing a radiation image storage panel of the present invention is capable of simultaneously sintering a large number of phosphor layer forming material molded products with uniform quality in - times of firing treatment (batch). It turns out that

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing an example of lamination of a sheet-like molded material for forming a phosphor layer and ceramic vapor in the present invention. FIG. 2 shows another example of the lamination of the phosphor layer-forming material sheet-like molded product and ceramic vapor in the present invention.
FIG. 2 is a schematic cross-sectional view. As is clear from the results shown in Table 1, 20 radiation images 1a, 1b obtained by the production method of the present invention: Phosphor layer forming material sheet shaped molded products 2a, 2b: Ceramic vapor 3: Heat resistant Plate 4: Gripping tool

Claims (1)

[Claims] 1. In a method for manufacturing a radiation image storage panel having a sintered phosphor layer made of aggregates of stimulable phosphor, two or more sheets of
A radiation image conversion panel characterized in that a phosphor layer is formed by sintering sheet-shaped phosphor layer-forming materials laminated with ceramic paper that does not substantially contain organic matter interposed therebetween. Manufacturing method.