JPH02278198A - Manufacture of radiation image conversion panel - Google Patents

Abstract

PURPOSE:To get higher sharpness and granularity by putting a fulorescent sheet on a carrier body and by adhering the sheet to the carrier body through compressing them at a temperature higher than a softening point or a melting point of a binder. CONSTITUTION:A fluorescent sheet consists of a binder and a stimulated phosphorescent body. Those two materials are put on a carrier body at a temperature higher than a softening point or a melting point of the binder, and simultaneously compressed. As fluorescent crystals dispersed in the binder of the sheet get pressurized at a condition having a certain degrees of freedom, and also the sheet gets pressurized at a condition not being fixed to the carrier, the pressure works in a direction to arrange the fluorescent crystals in a good order, even if the pressure is high enough to break-down the crystals in case that the sheet be fixed firmly, and, at the same time, the pressure works in a direction to spread the sheet widely and thinly. As the results, the packing of the fluorescent bodies can be improved without breaking-down the crystals and also a much better image quality (sharpness- granularity) can be obtained.

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 stimulable phosphor, and the panel converts the radiation transmitted through or emitted from the subject into By absorbing the stimulable phosphor into the stimulable phosphor, and then exciting the stimulable phosphor with electromagnetic waves (excitation light) such as visible light or infrared rays in a chronological order, the stimulable phosphor is accumulated in the stimulable phosphor. A device that emits radiation energy as fluorescence (stimulated luminescence light), reads this fluorescence photoelectrically to obtain an electrical signal, and reproduces a developable radiation image of the subject or subject based on the obtained electrical signal. It is.

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 very high utility value especially in direct 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 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 amount of radiation, and the radiation image of the subject or subject is stored on the panel. is formed as an accumulated image of radiation energy. This accumulated image can be emitted as stimulated luminescence light by irradiation with E excitation light, and this stimulated luminescence light can be read photoelectrically. By converting the energy into energy signals, it becomes possible to visualize the accumulated radiation energy.

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 that the absorption of radiation such as X-rays is also high, resulting in a higher sensitivity and at the same time an improvement in 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.

The present applicant has developed a radiation image conversion panel that has a phosphor layer densely packed with phosphors, in which the porosity of the phosphor layer is reduced by compressing the phosphor layer. and has already filed an application for its manufacturing method (
JP-A-59-126299, JP-A-59-126
(See Publication No. 300).

In the radiation image conversion panel described above, the density of the phosphor in the phosphor layer was made higher than that of previous radiation image conversion panels by compressing the phosphor layer. the result,
This radiation image conversion panel has excellent sharpness, but on the other hand, there is a problem in that the phosphor is partially destroyed by the compression process, so the graininess may actually deteriorate. there were.

[Summary of the Invention] An object of the present invention is to provide a method for manufacturing a radiation image storage panel that can reduce the porosity in a phosphor layer without destroying the phosphor.

Another object of the present invention is to provide a method for producing a radiation image conversion panel that can produce a radiation image conversion panel that has excellent sharpness and graininess.

The second object of the present invention is to produce a radiation image storage panel substantially composed of a support and a phosphor layer provided on the support and comprising a binder and a stimulable phosphor. A method comprising: a) forming a phosphor sheet made of a binder and a stimulable phosphor; b) placing the phosphor sheet on a support and heating the phosphor sheet to a temperature higher than the softening temperature or melting point of the binder. This can be achieved by a method for producing a radiation image storage panel, comprising the step of adhering the phosphor sheet onto a support while compressing it at a temperature of

In the present invention, the phosphor sheet to become the phosphor layer is compressed at a temperature higher than the softening temperature or melting point of the binder, and at the same time as it is placed on the support. Therefore, during 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 crystals that form the phosphor layer The sheet is subjected to pressure without being fixed to a support. Therefore, even if the phosphor sheet is fixed under pressure that would destroy the crystals, it will work to orient the phosphor crystals and at the same time work to spread the sheet thinly.

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

Preferred embodiments of the present invention are listed below.

(1) A method for producing a radiation image storage panel, characterized in that the distribution mixture is a thermoplastic elastomer.

(2) The binder has a softening temperature or melting point of 30 to 30
A method for producing a radiation image storage panel, characterized in that the panel is made of a thermoplastic elastomer having a temperature of 0°C.

(3) The binder has a softening temperature or melting point of 30 to 20
A method for producing a radiation image storage panel, characterized in that the panel is made of a thermoplastic elastomer having a temperature of 0°C.

(4) The binder has a softening temperature or melting point of 30 to 15
A method for producing a radiation image storage panel, characterized in that the panel is made of a thermoplastic elastomer having a temperature of 0°C.

(5) A method for producing a radiation image conversion panel, which comprises providing an adhesive layer and/or a light reflecting layer on a support in advance, prior to step b).

(6) A method for producing a radiation image storage panel, characterized in that the compression in step b) is performed using a calendar roll.

(7) Compression in step b) above to 50 gw/c
A method for manufacturing a radiation image conversion panel, characterized in that the manufacturing method is performed at a pressure of m2 or more.

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

The method for producing a radiation image storage panel of the present invention includes a) forming a phosphor sheet made of a binder and a stimulable phosphor, b) placing the phosphor sheet on a support, and following the steps of 1. The phosphor sheet is bonded onto a support while being compressed at a temperature higher than the softening temperature or melting point of the agent.

First, step a) will be described.

The phosphor sheet that becomes the phosphor layer of the radiation image conversion panel is
It can be manufactured by applying a coating liquid in which the stimulable phosphor is uniformly dispersed in a binder solution onto a temporary support for forming a phosphor sheet, drying it, and then peeling it off from the temporary support.

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

As mentioned above, a stimulable phosphor is a phosphor that exhibits stimulated luminescence when irradiated with radiation and then irradiated with excitation light.
From a practical standpoint, it is desirable that the phosphor be a phosphor that exhibits stimulated luminescence in the wavelength range of 300 to 500 nm when excited by excitation light in the wavelength range of 400 to 900 nm. Examples of the stimulable phosphor used in the method of manufacturing the radiation image storage panel of the present invention include Ba5 described in JP-A-48-80487.
O,: AX and 5rSO,: AX described in JP-A-48-80489; phosphor represented by AX; Li described in JP-A-53-39277;
2B 407: Cu, Ag, JP-A-1983-
Li2O・(B20
□) X: Cu and Li20・(B 2 02
) X 2 Cu, A g
, SrS:Ce, Sm, SrS:Eu as described in U.S. 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-xAj220):Eu (however, 0.8≦X≦10), and M"O xsi02
:A (However, Ml is Mg, Ca, Sr, Zn, Cd
, or Ba, where A is Ce, Tb, Eu, Tm, P
b, Tll, Bi.

or Mn, and X is 0.5≦X≦2.5)
, described in Japanese Patent Application Laid-Open No. 55-12143 (Ba
t-x-y, Mgx, Cay) FX:aEu'' (where X is at least one of C2 and Br,
X and y are 0x+y≦0.6 and xy≠0, and a is 10-'≦a≦5X10-', LnO described in JP-A-55-12144
X: xA (Ln is at least one of La, Y, Gd, and Lu, X is CfL and Br
A is at least one of Ce and Tb; (Ba, -X, M2°1) FX: yA (However, M2°
is at least one of Mg, Ca, Sr, Zn, and Cd, X is at least one of C1, Br, and ■, A is Eu, Tb, Ce, Tm, Dy, Pr
, Ho, Nd, Yb, and Er, where X is 0≦X≦0.6, and y is 0≦y
≦0.2), Ba described in JP-A No. 55-843897
FX: Phosphor expressed by xCe, yA JP-A-1983-
M”FX-xA described in Publication No. 160078:
yLn [Tatashi, Ml are Ba, Ca, Sr, Mg, Z
n, and at least one of Cd, A is Bed,
MgO1CaO, SrO, Bad, ZnO, Al2O2
,Y.

O7, La20), In2O3,5i02, TiO2,
ZrO2, GeO2, 5n02, Nb2O6, Ta20
6, and at least one of ThO2, Ln is E
u, Tb, Ce, Tm, Dy, Pr, )(o, Nd
, Yb, Er, Sm, and Gd, X is at least one of C1, Br, and I, and X and y each satisfy 5xlO-5≦X
≦0.5, and o<y≦0.2].
a, -y, M' x) F2 ・aBaX2yEu, 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, A is at least one of zirconium and scandium, a, x, y, and Z are each 0.5≦a≦1.25.0≦X≦1.10
Phosphor represented by the composition formula -6≦y≦2X10-' and 0<z≦10-2], JP-A-57-236
Described in Publication No. 73 (Bat-x, M”x)
F2 ・aBaX2: yEu, zB [However, M" 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 each 0.5≦a≦1
．． 25.0≦X≦1.1O-6≦y≦2×10-' and O<z≦2X10-' A phosphor described in JP-A-57-23675 (Ba
, -2,M' x)F2 ・aBaX2yEu,zA
[However, Ml is at least one of helillium, 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 Z are each 0.5
≦a≦1.25.0≦X≦1.10-6≦y≦2×10
-゛, and a phosphor represented by the composition formula of J with 0<z≦5X10-', M"O described in JP-A-58-69281
X: xCe [However, MII is Pr, NdPm,
Sm, Eu, Tb, Dy, Ho,
Er.

At least one trivalent metal selected from the group consisting of Tm, Yb, and Bi, X is one or both of Cl2 and Br, and X is 0<x
A phosphor represented by the composition formula <0.1] B described in JP-A-58-206678
a l-x M x /2 L 11 /2 F X
: y E u ” [However, M is Li, Na,
Represents at least one alkali metal selected from the group consisting of Rb and Cs; L represents Sc, Y, La, Cs;
e, Pr, Nd, Pm, Sm, Gd, Tb, DyvHo
, Er, Tm, Yb, Lu, An, Ga, In, and TIl; X represents at least one halogen selected from the group consisting of Cil, Br, and I; and X is 10-2≦X≦0.5, and y is o<y≦0.1. BaF
X −xA: yEu” [Tatashi, X is C2, B
r, and at least one kind of halogen selected from the group consisting of ■; 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] x M described in JP-A No. 59-38278
3 (P 04)2・N X2:y A, M3(P
OJ2:yA and nReX3-mAX'2:xE
u, nReX3・mAX'2: xEu, ySm, M'
X -aM"X'・b M"'X":+:CA
BaFX-xA described in JP-A No. 59-47289: yEu2+ [However, X is at least one halogen selected from the group consisting of C1l, Br, and I, and zA is , a fired product of at least one compound selected from the hexafluoro compound group consisting of monovalent or divalent metal salts of hexafluorosilicic acid, hexafluorotitanic acid, and hexafluorozirconic acid; and X is 10-6 ≦
BaFX-xNaX':aEu'', a phosphor represented by the composition formula: [However, X and X゛ are Cl3, Br, and ■
A phosphor is at least one of the following, and X and a are respectively 0<x≦2 and O<a≦0.2. The listed M”
FX-xNaX':yEu'':zA [However, Ml is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; X and X'' are C1, B'', and At least one halogen selected from the group consisting of I, and zA is V, Cr,
At least one transition metal selected from Mn, FeCO3 and Ni: and X is 0<x≦2, y is 0
<, y≦0.2, and Z is O<z≦10−2]
A phosphor represented by the composition formula M”F described in Japanese Patent Application Laid-open No. 75200/1983
X-aM'X'・bM'"X"2cM"X-
'2 HxA: yEu"" [However, Ml is Ba,
is at least one alkaline earth metal selected from the group consisting of Sr and Ca, and M + is Li, Na,
is at least one alkali metal selected from the group consisting of Rh and Cs; M゛1 is Be and M
is at least one divalent metal selected from the group consisting of g, and M Ill is All, Ga, In, and Tρ
at least one trivalent metal selected from the group consisting of; A is a metal oxide; X is at least one halogen selected from the group consisting of Cfi, Br, and I; and x” is F, Cl3, Br,
and ■ at least one kind of halogen selected from the group consisting of: and a is 0≦a≦2, b is 0≦b≦1
0-2, C is 0≦C≦to-' and a+b+c≧10-
6, where X is O<x≦0.5 and y is o<y≦0.2. ”X
2 ・aM"X' 2 :xEu'° [However, Ml
is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca;
1, at least one halogen selected from the group consisting of Br and ■, and X≠X゛; and a
is 041≦a≦10.0, and X is 0<x≦0.2]
A stimulable phosphor represented by the composition formula M" described in JP-A-60-101173
FX-aM 'X': xEu'' [However,
Ml is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr and Ca; Ml is at least one kind of alkali metal selected from the group consisting of Rb and Cs; X is selected from Cl, Br and I; is at least one kind of halogen selected from the group;
, Cfl, Br, and I; and a and X are 0≦a≦4,0 and O<x≦0.2, respectively]. Exhaustible phosphor, M'X described in JP-A No. 62-25189
:xBi [where Ml is at least one alkali metal selected from the group consisting of Rb and C5;
is at least one kind of halogen selected from the group consisting of Cft, Br and I: and X is O<x≦0.2
Examples include a stimulable phosphor represented by the composition formula [with a numerical value in the range].

In addition, as described in the above-mentioned Japanese Patent Application Laid-Open No. 60-84381,
M"X2- aM"X'2: xE
The u” stimulable phosphor contains the following additives:
It may be contained in the following proportions per mole of X2·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 Rb and Cs, X" is at least one kind of halogen selected from the group consisting of F, CR5Br and ■, and b is o<bSiO,
0): bKX"cMgX"2-dM"X"'3 which is not described in JP-A No. 60-221483
(However, Ml is at least one trivalent metal selected from the group consisting of Sc, Y, La, Gd and Lu,
X'' Both X'' and X'' are at least one kind of halogen selected from the group consisting of F, C2, Br and I, and s, c and d each satisfy 0≦b≦2.
0, O≦C≦2゜0.0≦d≦2.0, and 2
X10-'≦b+c+a); JP-A-60-228
yB described in Publication No. 592 (however, y is 2X
10"'≦y≦2xlO-'): JP-A-1983
bA (Tatashi,
A is at least one oxide selected from the group consisting of 5in2 and R20, and b is 10-4≦b
≦2×10−″); bSiO (j: dashi, b is 0<b
≦3x 10-'); JP-A-61-120885
bSnX" 2 (However, X
" is at least one kind of halogen selected from the group consisting of F, Cfl, Br and I, and b is o<b
bCsX'' and cSnX''2 (where X'' and X'' are respectively from the group consisting of F, CIl, Br and At least one kind of halogen is selected, and b and C are respectively o<bSiO,
0 and 10-6≦C≦2×10-2): and bCs described in JP-A No. 235487 in 1987
X"・y Ln'.

(However, X" is at least one kind of halogen selected from the group consisting of F, Cfl, Br and I, and Ln is Sc, Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy
, Ho, Er, Tm, Yb and Lu, and b and y are respectively o<bSiO, 0 and 10-6≦
y≦1.8x t o-').

Among the stimulable phosphors listed in JY, divalent europium-activated alkaline earth metal halide phosphors and cerium-activated rare earth oxyhalide 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.

Add the above-mentioned stimulable phosphor and binder to a suitable solvent and mix thoroughly to prepare a coating solution in which the stimulable phosphor is uniformly dispersed in the binder solution. .

As the binder, a thermoplastic elastomer that is elastic at room temperature and becomes fluid when heated is preferably used. Examples of thermoplastic elastomers include polystyrene, polyolefin, polyurethane, polyester,
Examples include polyamide, polybutadiene, ethylene vinyl acetate, polyvinyl chloride, natural rubber, fluororubber, polyisoprene, chlorinated polyethylene, styrene-butadiene rubber, and silicone rubber.

Among the above thermoplastic elastomers, those having a softening temperature or melting point of 30°C to 300°C are generally used, preferably 30°C to 200°C, and 30°C to 15°C.
It is more preferable to use one at 0°C.

Examples of solvents for preparing coating solutions include lower alcohols such as methanol, ethanol, n-propanol, and n-butanol; chlorine-containing hydrocarbons such as methylene chloride and ethylene chloride; acetone, methyl ethyl ketone, and methyl isobutyl ketone. Ketones such as; esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate, and butyl acetate; ethers such as dioxane, ethylene glycol ethyl ether, and ethylene glycol monomethyl ether; and mixtures thereof. be able to.

The mixing ratio of the binder and the stimulable phosphor in the coating solution varies depending on the characteristics of the intended radiation image conversion panel, the type of phosphor, etc., but generally the mixing ratio of the binder and the stimulable phosphor is 1. :1 to 1:100 (weight/jt ratio), and particularly preferably from 1.8 to 140 (weight ratio).

Note that the coating solution contains a dispersant to improve the dispersibility of the phosphor in the coating solution, and a dispersant to improve the bonding force between the binder and the phosphor in the phosphor layer after formation. Various additives such as plasticizers may be mixed. Examples of dispersants used for such purposes include phthalic acid, stearic acid, caproic acid, lipophilic surfactants, and the like. Examples of plasticizers include phosphate esters such as triphenyl phosphate, tricresyl phosphate, and diphenyl phosphate; phthalate esters such as diethyl phthalate and dimethoxyethyl phthalate; ethyl phthalyl ethyl glycolate, butyl phthalyl glycolate, etc. Polyesters of polyethylene glycol and aliphatic dibasic acids, such as polyesters of triethylene glycol and adipic acid and polyesters of diethylene glycol and succinic acid, can also be mentioned.

The coating liquid containing the phosphor and binder prepared as described above is then uniformly applied to the surface of a temporary support for sheet formation to form a coating film of the coating liquid. This coating operation can be carried out using conventional coating means such as a doctor blade, roll coater, knife coater, etc.

Temporary supports include, for example, glass, metal plates, various materials used as supports for intensifying screens in conventional radiography, or supports for radiation image conversion panels. It can be arbitrarily selected from materials known as . Examples of such materials include:
Films of plastic materials such as cellulose acetate 5 polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, polycarbonate, metal sheets such as aluminum foil, aluminum alloy foil, ordinary paper, baryta paper, resin coated paper, pigments such as titanium dioxide, etc. Examples include pigment paper containing pigment, paper sized with polyvinyl alcohol, plates or sheets of ceramics such as alumina, zirconia, magnesia, and titania.

A coating solution for forming a phosphor layer is applied onto a temporary support, and after drying, it is peeled off from the temporary support to obtain a phosphor sheet that will become a phosphor layer of a radiation image conversion panel.

Therefore, it is preferable to apply a release agent to 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 manufacturing a radiation image storage panel of the present invention will be described.

First, a support for a radiation image conversion panel is prepared separately from the phosphor sheet formed as described above.

This support can be arbitrarily selected from the same materials as the temporary support used when forming the phosphor sheet.

In 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 ceratin is coated on the surface of the side support to form an adhesion-imparting layer, or a light-reflecting layer made of a light-reflecting substance such as titanium oxide, or a light-absorbing substance such as carphone black. It is known to provide a light absorption layer or the like. In the present invention, the Hl undulating support can also be provided with these various layers, and their configurations can be arbitrarily selected depending on the purpose, use, etc. of the desired radiation image storage panel.

Generally speaking, as described in JP-A-58-200200, in order to improve the sharpness of the obtained image, the surface of the support on the phosphor layer side (the phosphor layer side of the support) When an adhesion-imparting layer, a light-reflecting layer, a light-absorbing layer, or the like is provided on the surface of the substrate, minute irregularities may be formed on the surface (meaning the surface thereof).

The phosphor sheet obtained in step a) is placed on a support and adhered onto the support while being compressed at a temperature equal to or higher than the softening temperature or melting point of the binder.

Examples of compression devices used for the compression treatment of the present invention include commonly known devices such as calender rolls and hot presses. For example, the compression treatment using calender rolls is carried out by placing the 4Q phosphor sheet in step a) on support-F and passing it at a constant speed between rollers heated above the softening temperature or melting point of the binder. It will be done. However, the compression device used in the present invention is not limited to these devices, and any device may be used as long as it can compress the sheet as described above while heating it.

The pressure during compression is generally 50 kgw/cm2 or more.

The porosity of the phosphor layer formed on the support as described above can be theoretically determined by the following equation (1).

Below margin Vair/V= (a+b)p x p y V A (ap r
+ bρx )Vair/V= (a+b)ρ x p yV-A (apy+
bρ x)V [(a” b)pxpy-apyp
a ir −b ρ x ρ air] (however,
V : Total volume of the phosphor layer Vair : Volume of air in the phosphor layer A : Total weight of the phosphor layer ρx : Density of the phosphor ρ, : Density of the binder ρair : Density of air a : Weight of the phosphor b : weight of binder) Furthermore, in equation l), ρair is almost 0, so
Equation (1) can be approximately expressed by the following equation (rr).

Below margin V [(a+b)ρtsupy co---(II) (However, V, Vair, A, p X, py,
In the present invention, the porosity of the phosphor layer was calculated using equation (II).

Further, the filling rate of the phosphor can be determined by the following equation (III).

apy V [(a+b)ρ x p yE---(III
) (However, V, Vair, A, p X, py,
The definitions of a and b are the same as in formula (1)) In a normal radiation image conversion panel, a phosphor layer is formed on the surface of the phosphor layer on the side opposite to the side in contact with the support as described above. A transparent protective film is provided for physical and chemical protection. Such a transparent protective film is preferably provided also in the radiation image conversion panel according to the present invention.

The transparent protective film may be made of, for example, a cellulose derivative such as cellulose acetate or nitrocellulose; or a synthetic polymer material such as polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, or vinyl chloride/vinyl acetate copoir. It can be formed by applying a solution prepared by dissolving a transparent polymer substance in a suitable solvent onto 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 using an appropriate adhesive. It can also be formed by the following method.

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, 1
A colored layer that absorbs excitation light but does not absorb stimulated emission light may be added to at least one of the layers mentioned above (see Japanese Patent Publication No. 59-23400).

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

[Example 1] As a coating liquid for forming a phosphor sheet, phosphor: BaF
Bro 910 r:Eu"・---・-200g Binder: Polyurethane (Sumitomo Bayer Urethane Desmolac TPKL-5-
2625 [solid content 40%])・22.5g Anti-yellowing agent:
Epoxy resin (oiled shell epoxy ■ Epicoat 1001) ・・・・・ 1. Add Og to a 1:1 mixed solvent of methyl ethyl ketone and 2-propenol and disperse with a propeller mixer until the viscosity is 3.
A 0PS (25°C) coating solution was prepared (binder/phosphor ratio = 1720). Polyethylene terephthalate (temporary support, thickness 1
After drying, the phosphor sheet was peeled off from the temporary support to form a phosphor sheet.

On the other hand, as a coating liquid for forming a light reflective layer, BaFBr (90% of particles with a particle size in the range of 1 to 5 μm) was used.
Contains)...214g Soft acrylic resin solid content...25.7g Epoxy resin...
...10.7g nitrocellulose (nitrification degree 11.5
%, solid content 1011%)...64g to 5
It was added to methyl ethyl ketone and dispersed with a propeller mixer to prepare a dispersion having a viscosity of 25 to 35 PS (25°C).

Separately, as a coating liquid for forming an undercoat layer, 90 g of soft acrylic resin solids and 50 g of nitrocellulose were added to methyl ethyl ketone and dispersed and mixed. and the viscosity is 3 to 8 PS (
25°C) was prepared.

A polyethylene terephthalate (support) with a thickness of 300 μm was placed horizontally on a glass plate, and the coating solution for forming the undercoat layer was uniformly applied onto the support using a doctor blade, and then the temperature was gradually increased from 25°C to 100°C. The coating film was dried by raising the temperature to 100.degree. C. to form an undercoat layer on Support-F (coating film thickness: 215 μm). Furthermore, the above-mentioned coating solution for forming a light-reflecting layer was coated (coating film thickness: 60 μm) and dried in the same manner to form an undercoat layer and a light-reflecting layer on the support. The previously prepared phosphor sheet was placed on top of this and compressed.

Compression was done using calender rolls at 400K g w.
It was carried out continuously at a pressure of / cm 2 and a temperature of 80 °C. Due to this compression, the phosphor sheet and the light reflecting layer on the support were completely fused together.

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

In the manner described above, a radiation image storage panel comprising a support, an undercoat layer, a light reflection layer, a phosphor layer, and a transparent protective film was manufactured.

[Actual bK Example 2] In Example 1, the pressure during compression was set to 600 g w
/cm2.
4′? A radiation image conversion panel was manufactured, which consisted of a body, a Σ coating layer, a light reflecting layer, a phosphor layer, and a transparent protective film.

[Example 3] In Example 1, the pressure during compression was set to 800K g w.
/cm'', but in the same manner as in Example 1, a radiation image storage panel was produced comprising a support, an undercoat layer, a light reflection layer, a phosphor layer, and a transparent protective film.

[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 this coating IIq was dry, a coating for forming a phosphor layer was applied on top of this. The liquid was applied. This was dried by gradually raising the temperature from 25° C. to 100° C. to form a sheet consisting of a support, an undercoat layer, a light reflective layer, and a phosphor layer. Next, this sheet was heated to 400 kg/c using a calender roll in the same manner as in Example 1.
It was compressed at a pressure of m 2 and a temperature of 80°C. moreover,
A protective film was provided by the same method as in Example 1, and the support was
A radiation image storage panel was produced which was composed of a subbing layer, a light reflecting layer, a phosphor layer, and a transparent protective layer.

[Comparative Example 2] In Comparative Example 1, the pressure during compression was set to 600K gw.
/ cm 2 A radiation image conversion panel composed of a support, an undercoat layer, a light reflection layer, a phosphor layer, and a transparent protective film was produced in the same manner as in Comparative Example 1 except that the ratio was 1.2 cm.

[Comparative Example 3] In Comparative Example 1, the pressure during compression was 800K z w
A radiation image conversion panel comprising a support, an undercoat layer, a light-reflecting layer, a phosphor layer, and transparent protection 11Q was produced in the same manner as in Comparative Example 1, except that the ratio was 11Q.

[Comparative Example 4] A radiation image converter constructed from a support, an undercoat layer, a light reflective layer, a phosphor layer, and a transparent protective film in the same manner as in Comparative Example 1 except that no compression was performed. Manufactured the panel.

The phosphor filling rate and the porosity in the phosphor layer of each of the radiation image conversion panels of Examples and Comparative Examples, which were manufactured as described above, are expressed by formula (II). and (III). However, the density of the phosphor is 5.1 g/am3, and the density of the binder is 1.14 g/Cm3.

The results are shown in Table 1.

Below is the margin 1 table Pressure (kg/crn") Phosphor layer 1! Porosity (%) (%) Example 1 Comparative example 1 70゜6 66.7 13.6 18.4 Example 2 Comparative example 2 72.5 68.7 11.3 15.9 Example 3 Comparative Example 3 74.5 70.7 8.8 13.6 Comparative Example 4 None 58.8 28.0 1st
As is clear from the table, the radiation image storage panel manufactured according to the present invention has a higher phosphor filling rate and a lower porosity than the conventionally manufactured panel compressed with the same pressure. It turns out that it is something.

In addition, the image quality of each radiation image storage panel manufactured as described in Section F was evaluated by the method described below. That is, the radiation image conversion panel is
After irradiating the beam, a He-Ne laser beam (632,8
The phosphor is excited by scanning at 50 nm), the stimulated luminescence emitted from the phosphor layer is received and converted into an electrical signal, and this is reproduced as a °C image by an image reproducing device and displayed on the display device F. Got the image. The sharpness is determined by the modulation transfer function (MTF) (spatial frequency: 2 cycles/mm) of the obtained image.
In addition, the graininess (RMS) at doses of 0 and 1 mR was measured.

The results obtained are summarized and shown in graph form in FIG.

In Figure 1, the vertical axis shows sharpness (spatial frequency 2 cycles/
(MTF value at mm), and the higher the plot is, the higher the sharpness is. The horizontal axis indicates graininess, and the farther left the plot is, the better the graininess is.

As is clear from FIG. 1, the radiation image storage panel manufactured according to the present invention has slightly improved sharpness and graininess compared to a conventionally manufactured panel compressed with the same pressure. It can be seen that there has been a significant improvement in gender.

[Brief explanation of drawings]

FIG. 1 is a graph showing the image quality of radiation image conversion panels according to Examples and Comparative Examples. Patent applicant Fuji Photo Film Co., Ltd. Agent Patent attorney Hatao Yanagawa

Claims (1)

[Claims] 1. A method for producing a radiation image storage panel substantially composed of a support and a phosphor layer provided on the support and comprising a binder and a stimulable phosphor, the method comprising: a) a binder and a stimulable phosphor; b) placing the phosphor sheet on a support and supporting the phosphor sheet while compressing it at a temperature equal to or higher than the softening temperature or melting point of the binder; A method for producing a radiation image conversion panel, comprising the step of adhering it onto a body.