JPH0452600A - Manufacture of radiation image converting panel - Google Patents

Abstract

PURPOSE:To enhance sharpness and graininess by a method wherein a phosphor sheet is superposed on a support while tension is applied to the phosphor sheet and both of them are heat-treated under pressure by a heating calender roll. CONSTITUTION:A coating solution for forming a phosphor sheet is prepared to be applied to a temporary support and, after drying, the coating layer is peeled off from the temporary support to form the phosphor sheet 13. A coating solution for forming an under coating layer is prepared to be applied to a support 15 to form an undercoating layer. Further, a coating solution for forming a light reflecting layer is prepared to be applied to the undercoating layer to form the undercoating layer and the light reflecting layer on the support 15. Then, the sheet 13 and the support 15 are superposed one upon another using a calendering treatment apparatus consisting of a calender roll 11, a torque roll 12 and a tension pick-up roll 14 and subjected to heating calendering treatment under a predetermined condition. Next, a transparent film whose single surface is coated with an adhesive is bonded after calendering treatment to form a transparent protective film. By this method, the voids in a phosphor layer can be reduced without destructing a phosphor.

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 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.

In addition, a transparent protective film is usually provided on the surface of the stimulable phosphor layer opposite to the support (the surface not facing the support), and the phosphor layer is protected from chemicals. Protects from 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.

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 its manufacturing method, and the application has already been published (see JP-A-59-126299 and JP-A-59-126300).

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 present invention is a method for producing a radiation image conversion panel substantially composed of a support and a phosphor layer provided on the support and comprising a binder and a stimulable phosphor, comprising: a) a step of forming a phosphor sheet consisting of a binder and a stimulable phosphor, b) overlapping the phosphor sheet and the support while applying tension to the phosphor sheet, and stacking this with a heated calendar roll; The manufacturing method is characterized by comprising the steps of applying pressure and heat treatment and thereby bonding the phosphor sheet to a support.

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 bonded onto 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, when the manufacturing method of the present invention is used, the phosphor crystals are arranged so as to be oriented even under conditions that would destroy the crystals if the phosphor sheet was fixed and subjected to compression treatment. At the same time, the phosphor sheet itself is also thinly stretched and expanded. Therefore, according to the manufacturing method of the present invention, in the radiation image conversion panel obtained, the phosphor crystals are not destroyed, the phosphor filling rate is improved,
At the same time, the orientation of the phosphor is improved, and a homogeneous and thin phosphor layer can be easily formed.

Further, the compression step in the present invention is performed while applying tension to the phosphor sheet. That is, according to the research of the present inventor, when a laminate of a phosphor sheet and a support is simply placed on a calender roll and subjected to heat and pressure treatment, the phosphor sheet that has been compressed becomes more compact than the support. It was found that the phosphor layer of the resulting radiation image conversion panel is likely to suffer from problems such as wrinkles, distortion, and non-uniform adhesion. Therefore, in the present invention, the occurrence of the above-mentioned trouble can be effectively and easily avoided by carrying out the calender roll treatment while applying tension to the phosphor sheet. Therefore, the radiation image conversion panel manufactured according to the present invention can provide images with particularly excellent image quality such as graininess and sharpness.

Preferred embodiments of the present invention are listed below.

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

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

(5) Adjust the tension applied to the phosphor sheet so that the length of the phosphor sheet under heating is 1.01 to 2.5 times the length before applying tension and heating. , a method for manufacturing a radiation image conversion panel according to the present invention.

(6) Adjust the tension applied to the phosphor sheet so that the length of the phosphor sheet under heating is 1.05 to 1.5 times the length before applying tension and heating. , a method for manufacturing a radiation image conversion panel according to the present invention.

(7) The tension applied to the phosphor sheet is 10 to 700.
A method for producing a radiation image storage panel according to the invention, adjusting within the range of g/cm.

(8) The tension applied to the phosphor sheet is 20 to 500.
A method for producing a radiation image storage panel according to the invention, adjusting within the range of g/cm.

[Description 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 conversion panel of the present invention includes a) forming a phosphor sheet made of a binder and a stimulable phosphor, and b) forming a phosphor sheet while applying tension to the phosphor sheet. The phosphor sheet is laminated with a support and subjected to pressure and heat treatment using a heated calendar roll, thereby bonding the phosphor sheet onto the support.

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, and then peeling it off from the temporary support after drying.

The stimulable phosphor used in the present invention is a phosphor that exhibits stimulated luminescence when it is irradiated with radiation and then irradiated with excitation light as described above, but from a practical point of view, the wavelength is 40.
300 to 5 by excitation light in the range of 0 to 900 nm.
It is desirable that the phosphor be a phosphor that exhibits stimulated luminescence in a wavelength range of 0.00 nm.

Examples of the stimulable phosphor used in the method of manufacturing the radiation image storage panel of the present invention include BaS described in JP-A-48-80487.
O4: AX and SrSO4 described in JP-A-48-80489: Phosphor represented by AX, Li2 described in JP-A-53-39277
B4O, :Cu, Ag, Li2 described in JP-A-54-47883
0-(B202),: Cu and Li2O・(Bz
02) X: Cu, Ag, US Patent No. 3,859,
SrS described in No. 527: Ce, Sm,
SrS:Eu.

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

ZnS described in Japanese Patent Application Laid-Open No. 55-12142
:Cu, Pb, Ba0-xA120):Eu(However,
0.8≦X≦10), and M”0−xsi02:
A (However, Ml 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)
, is described in Japanese Patent Application Laid-open No. 55-12143 (B
at-x-y+ Mg x, Ca y) FX: aEu
”(However, X is at least one of C1 and Br, X and y are 0<x+y≦0.6, and x
y≠0 and a is 10-6≦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 C1L
and Br, A is Ce and T
At least one of b, and X is 0<x<0
．． 1), described in JP-A-55-12145 (Ba
, -1, M"x) FX: yA (However, M is M
At least one of g, Ca, Sr%Zn, and Cd, X is at least one of CIl, Br, and I, A is Eu, Tb, Ce, 7m%Dy%Pr%H
o% At least one of 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 [However, M” is Ba, Ca, Sr, Mg, Z
n, and at least one of Cd, A is Be01
Mg0. CaO, 5rO1BaO1ZnO1AJ220
．． ,Y2O2,La2O3,In2O3,5i02,T
iO2, ZrO2, GeO2, 5n02, Nb.

05, Ta205, and ThO2, and Ln is Eu, Tb, Ce, or Tm.

Dy, Pr, )io, Nd%Yb, Er, S
m, and at least one of Gd, X is CI, B
r, and at least one of I, and X and y are respectively 5 X 10-'≦X≦0.5, and o
A phosphor represented by the composition formula <y≦0.2] is described in JP-A-56-116777 (B
a1-X+ M”X)F2・aBaX2:yE
u, 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. and a, x, y
, and 2 are respectively 0.5≦a≦1.25.0≦X≦
1.10-G≦y≦2xlO-' and O<z≦1
A phosphor represented by the composition formula of
7-23673 (B a r
-1, M ” z ) F 2 ・a B a X 2
:yEu, zB [where Ml is at least one of helillium, magnesium, calcium, strontium, zinc, and cadmium, and X is chlorine, bromine,
and at least one of iodine, a, x, y
, and Z are respectively 0.5≦a≦1.25.0≦X≦
1.10-6≦y≦2×10-” and O<z≦2
A phosphor represented by the composition formula of
at-In M” x) F 2 ・aBaX2 :yE
u, 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 arsenic and silicon. and a, x, y, and 2 are each 0.5≦a≦1.25.0≦X≦1.10−G≦y≦
2×10−′, and O<z≦5×10−′], M”O described in JP-A-58-69281
X: xCe [However, Mll is Pr, Nd,
Pm, Sm, Eu, Tb, Dy, Ho,
At least one trivalent metal selected from the group consisting of Er, Tm, Yb, and Bi, and X is C1 and Br.
one or both of these, and X is O
A phosphor represented by the composition formula <x<0.1], B described in JP-A No. 58-206678
a r-x M x /2 L x /2 F X:
y E u ” [However, M is Li, Na, R
h, and at least one alkali metal selected from the group consisting of Cs: L represents Sc, Y, La, Ce;
, Pr, Nd, Pm% Sm, Gd, Tb, Dy.

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

represents at least one type of trivalent metal selected from the group consisting of In and T1; X represents at least one type of halogen selected from the group consisting of Cl3, Br, and I; 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 I; 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] XM described in JP-A-59-38278
S(P 04)z・N X2:)' A, M3(P
04) 2:3'A and nReX3-mAX'2:
xEu, nReX3-mAX'2: xEu, ySm,
M"X -aM"X'2- bM1Y'X"3:c
The phosphor represented by A is BaFX-xA described in JP-A No. 59-47289: yEu" [However, X is at least one halogen selected from the group consisting of C1, Br, and I. 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; 10-6≦X
≦0.1, y is o<y≦0.1], BaFX-xNaX':aEu'' described in JP-A-59-56479 [However,
X and X' are each at least one of C1, Br, and I, and X and a are each O<x
≦2, and 0 < a≦0.2] A phosphor represented by the composition formula M" described in JP-A No. 59-56480
FX-xNaX':yEu'': zA [However, Ml
is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca;
are at least one kind of halogen selected from the group consisting of C1, Br, and I, respectively; A is V, Cr,
is at least one transition metal selected from Mn, Fe, Co, and Ni: and X is O<x≦2, y is o<y≦0.2, and Z is O<z≦10-2. be]
A phosphor represented by the composition formula M”F described in Japanese Patent Application Laid-open No. 75200/1983
X-aM'X'-bM'"X"2-cM"
X"', -xA: yEu" [However, Ml is Ba
, Sr, and Ca; Ml is at least one alkali metal selected from the group consisting of Li, Na, %Rb, and Cs; M' 1 is Be and Mg
is at least one divalent metal selected from the group consisting of: M1 is at least one trivalent metal selected from the group consisting of AfL, Ga, In, and Tl; A is a metal oxide; X is At least one halogen selected from the group consisting of C1, Br, and 1);
'x''' and X''' are at least one kind of halogen selected from the group consisting of F, Cl3, Br, and I: and a is 0≦a≦2, and b is O≦b≦10-
2. C is 0≦C≦10-2, and a+b+c≧10-G
, where X is 0<x≦0.5, and y is o<y≦0.2]. '
X 2- aM' is at least one kind of halogen selected from xsx'; and a is 0.1≦a≦10.0, and X is 0<x≦0.
A stimulable phosphor represented by the composition formula of
FX -aM'
and Cs; X is at least one halogen selected from the group consisting of CI, Br and I; x' is F%CIL, Br;

and at least one kind of halogen selected from the group consisting of 1; and a and X are each 0≦a≦4.
A stimulable phosphor represented by the composition formula: 0 and 0<x≦0.2;
: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 C1, Br, and can be mentioned.

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

It is described in Japanese Patent Application Laid-Open No. 60-166379
M'X'' (where Ml is at least one alkali metal selected from the group consisting of Rh and Cs, x
″ is at least one kind of halogen selected from the group consisting of F, C1l, Br@, and I, and b is o<bs
iO, 0); described in Japanese Patent Application Laid-Open No. 60-221483 6bKX"・cMgX"2 @ dM"
X"-z (t-dashi, Ml is at least one trivalent metal selected from the group consisting of Sc, Y, La, Gd and Lu, and Xo xl and xl are both F%Cf.

at least one species of halogen selected from the group consisting of Br and I, and s, c and d are each 0≦
b≦2.0, 0≦C≦2.0.0≦d≦2.0, and 2xlO−s≦b+c+d): JP-A-1987
-yB described in Publication No. 228592 (however, y
bA described in JP-A No. 60-228593 (wherein A is at least one oxide selected from the group consisting of 5i02 and P20I); , and b is 10-4
≦b≦2X10-"'l'exists); JP-A-61-120
bsiO described in Publication No. 883 (where b is o<
b≦3×10−′); JP-A-61-1208
bSnX”2 (however, x
” is at least one kind of halogen selected from the group consisting of F, CIL, BrJ5 and ■, and b is o<b
s10 bow); bCsX''-cSnX-'2 (however, X
” and xl are at least one kind of halogen selected from the group consisting of F, C1, Br, and summer, respectively, and b and C are o<bs10.0 and 10, respectively.
-6≦C≦2 x 10-'); and JP-A No. 6
bCsX” described in Publication No. 1-235487
-yLn'' (where X'' is at least one kind of halogen selected from the group consisting of F, Cf, Br and I,
Ln is Sc%Y, Ce, Pr, Nd, Sm, Gd, Tb
% At least one rare earth element selected from the group consisting of Dy, Ho, Er, Tm, Yb and Lu, and bs and y are o<bs10.0S and 1, respectively.
0-'≦y≦1.8X10-').

Among the above-mentioned stimulable phosphors, 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. It's okay to be lazy.

Thereafter, the margin stimulable phosphor and the binder are added to a suitable solvent and mixed 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; and acetone, methyl ethyl ketone, and methyl isobutyl ketone. Ketones: esters of lower fatty acids and lower alcohols such as methyl acetate, 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 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 ratio), and particularly preferably 1:8 to 1:40 (weight ratio).

The coating liquid also contains a dispersant to improve the dispersibility of the phosphor in the coating liquid, 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. and 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.

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, 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, and 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 in detail.

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 in forming the phosphor sheet, but is preferably a plastic support.

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 side support to form an adhesion-imparting layer, or a light-reflecting layer made of a light-reflecting substance such as titanium dioxide, or a light-reflecting layer made of a light-absorbing substance such as carbon black. It is known to provide an absorbent layer or the like. The support used in the present invention can also be provided with these various layers, and the structure of the layer can be arbitrarily selected depending on the purpose, use, etc. of the desired radiation image storage panel.

Furthermore, 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 surface of the support on the phosphor layer side) When an adhesion-imparting layer, a light-reflecting layer, a light-absorbing layer, etc. are provided, minute irregularities may be formed on the surface (meaning the surface thereof).

In step b), while applying tension to the phosphor sheet produced as described above, the phosphor sheet and the support are overlapped, and this is subjected to pressure and heat treatment using a heating calendar roll, thereby This is a step of bonding a phosphor sheet onto a support to obtain a radiation image storage panel.

A schematic diagram of an example of a tensioning device and calender roll system used to carry out step b) is shown in FIG.

In FIG. 1, the calender roll 11 includes an upper roll l
1a and a lower roll 11b. The device for applying tension to the phosphor sheet is shown as a torque roll 12 in FIG. This torque roll 12
The phosphor sheet 13 manufactured in step a) is wrapped around the torque roll 12 and the calender roll 11.
A desired tension (load) is applied to the phosphor sheet 13 due to the difference in rotation speed, rotation timing, etc. between the two. The tension (load) applied to the phosphor sheet 13 is detected by a load detection means such as a tension book-up roll 14, and the tension (load) detected there
is transmitted to the calender roll 11 or the torque roll 12 as necessary, and used to adjust the rotation conditions of each.

The support 15 is fed from a roll (not shown) separate from the phosphor sheet 13, and immediately before entering the calender roll 11,
The support and the phosphor sheet are overlapped.

As the calender roll, a calender roll similar to that used for calendering in the manufacture of magnetic recording tapes can be used, for example. A calender roll usually consists of a pair of rolls (a metal roll, a combination of a roll and a metal roll, a combination of a metal roll and a rubber roll, a combination of a rubber roll and a rubber roll, etc.). The phosphor sheet produced in step a) and the support are laminated into a sheet and processed by passing between a pair of rolls under pressure. Calendar roll treatment usually takes 50 to 20
00 kg w/cm2 pressure and 30~
It is carried out at a temperature of 200°C.

The tension applied to the phosphor sheet is usually such that the length of the phosphor sheet under heating is 1.01 to 2.5 times (preferably 1.05 times) the length before applying tension and heating. ~1.
5 times), that is, the elongation rate is 1 to 150%.
(preferably 5 to 50%).

In order to achieve the stretching conditions as described above, the tension applied to the phosphor sheet is adjusted within a range of, for example, 10 to 700 g/cm (preferably 20 to 500 g/cm). However, the tension applied to the phosphor sheet varies depending on the material, thickness, etc. of the phosphor sheet.

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

Vair/V= (a+b>pxpyV-A (apr+bpx)V[
(a+b) ρ xpy −apypair −b
px ρ air (where, V: Total volume of the phosphor layer Vair: Air volume in the phosphor layer A: Total weight of the phosphor layer ρ, : Density of the phosphor ρy: Density of the binder ρair: Density of the air a : weight of phosphor, b = weight of binder) In the above equation (1), since ρair is approximately 0, equation (1) can be approximately expressed by the following equation (II).

Vair/V= (a+b)p x p y V A (ap y 10bp x)V [(a+b) ρ summer ρ y 1
(II) (However, V, Vair, A, l:) x, ρ
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 (m).

Aaρy V [(a+b)ρ, ρy] ---(m) (However, V, Vair, A, ρ0, ρ7, a,
and b are the same as in formula (1)) In a normal radiation image conversion panel, the phosphor layer is physically attached to the surface of the phosphor layer on the side opposite to the side in contact with the support as described above. and a transparent protective film for 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 a transparent material such as 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 copolymer. It can be formed by coating the surface of the phosphor layer with a solution prepared by dissolving a polymeric substance in an appropriate solvent. Alternatively, plastic sheets made of polyethylene terephthalate, polyethylene naphthalate, polyethylene, polyvinylidene chloride, polyamide, etc.:
Alternatively, a protective film-forming sheet such as a transparent glass plate may be separately formed and adhered to the surface of the phosphor layer using a suitable adhesive.

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

Furthermore, for the purpose of improving the sharpness of the obtained image, a colored layer that absorbs excitation light but does not absorb stimulated emission light may be added to at least one of the above layers (Japanese Patent Publication No. 59-23400 (see issue).

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

[Example 1] As a coating liquid for forming a phosphor sheet, phosphor: BaFBro 91o, :Eu”
200 g Binder: Polyurethane elastomer (Bayer Urethane ■ Desmolak 4125 [solid content 40%]) 22.5 g Anti-yellowing agent: Epoxy resin (oiled shell epoxy ■ Epicoat 1007) 1.0 g was mixed with methyl ethyl ketone and 2-propyl Add to the 1:1 mixed solvent of the tool and disperse with a propeller mixer to reach a viscosity of 35P.
A coating solution of S (25° C.) was prepared (binder/phosphor ratio = 1/20). This was applied onto a polyethylene terephthalate sheet (temporary support, thickness: 180 μm) coated with a silicone mold release agent, dried, and then 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.
s%, solid content 10% by weight) 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).

Furthermore, as a coating liquid for forming an undercoat layer, soft acrylic resin solid content 90g nitrocellulose
50 g was added to methyl ethyl ketone and mixed to prepare a dispersion having a viscosity of 3 to 6 PS (25°C).

300 μm thick polyethylene terephthalate sheet (
The support) 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 raised from 25°C to 100°C to dry the coated film. to form an undercoat layer (thickness of coating film: 1
5μm). Furthermore, the above coating liquid for forming a light reflective layer was applied (coating film thickness = 60 μm) and dried in the same manner.
An undercoat layer and a light reflective layer were formed on the support.

Using a calendering device consisting of a calender roll, a torque roll, and a tension pick-up roll as shown in Figure 1, the phosphor sheet, the undercoat layer thereon, and the support with a light-reflecting layer were layered under the following conditions. The mixture was heated and calendered.

Roll temperature (upper roll) 80°C Roll temperature (lower roll) 80°C Calender roll applied pressure 500 kgw/cm2 Phosphor sheet feeding speed 1 m/min Phosphor sheet applied tension 30 g/cm By the above heat compression treatment, The phosphor sheet and the light reflecting layer on the support were completely fused together.

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

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.

[Example 2] The tension added to the phosphor sheet during heating calendering was 15
The same operation as in Example 1 was performed except that the thickness was changed to 0 g/cm, and the support, undercoat layer, light reflection layer, phosphor layer,
A radiation image storage panel constructed from a transparent protective film was manufactured.

[Example 3] The tension added to the phosphor sheet during heating calendering was set to 50
The same operation as in Example 1 was performed except that the thickness was changed to 0 g/cm, and the support, undercoat layer, light reflection layer, phosphor layer,
A radiation image storage panel constructed from a transparent protective film was manufactured.

[Comparative Example 1] A system of a calender roll 21 without a tensioning device as shown in FIG.
a, 21b, the tension applied to the phosphor sheet during heating calendering is set to Og/cm
A radiation image conversion panel comprising a support, an undercoat layer, a light reflection layer, a phosphor layer, and a transparent protective film was manufactured by carrying out the same operation as in Example 1, except that the following was changed.

゛ Sheet heating Example --- Comparative example Tension (g/ctn> Thickness (μm) Elongation rate before compression treatment and after compression treatment (%) 7 40 B6 of 2 panels
The image quality of the radiation image conversion panels obtained in Examples 1 to 3 and Comparative Example 1 was evaluated by the method described below.

That is, after irradiating the radiation image conversion panel with X-rays with a tube voltage of 8°KVp, a He-Ne laser beam (632,
8 nm) to excite the phosphor, receive stimulated luminescence emitted from the phosphor layer, convert it into an electrical signal, and reproduce this as an image using an image reproducing device to obtain an image on a display device. Ta.

Modulation transfer function (MTF) of the obtained image (spatial frequency =
sharpness by 2 cycles/mm) and 10 m
The graininess (RMS) in H dose was measured.

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

In Figure 3, 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. 3, the radiation image conversion panel manufactured according to the present invention has a higher sharpness than a radiation image conversion panel in which the phosphor sheet is heated and compressed without applying tension. It can be seen that they are almost the same and that the graininess is clearly improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a system of a tensioning device and a calender roll used in manufacturing the radiation image storage panel of the present invention. FIG. 2 is a schematic diagram showing a calender roll system without a tensioning device. FIG. 3 is a graph showing the image quality of radiation image conversion panels according to Examples and Comparative Examples. 11.21: Calendar rolls 11a, 21a: Upper calender roll flb, 21b: Lower calender roll 12: Torque roll (load applying means) 13° 23: Phosphor sheet: Tension kick-up roll 15° 25: Support body

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; Step of forming a phosphor sheet consisting of an exhaustible phosphor, b) Overlapping the phosphor sheet and the support while applying tension to the phosphor sheet, and pressurizing and heating this with a heating calendar roll. A manufacturing method comprising the steps of: treating the phosphor sheet, thereby bonding the phosphor sheet onto a support.