JPH0416800A - Fabrication of radiation image conversion panel - Google Patents

Abstract

PURPOSE:To enable obtaining a radiation image having high quality sharpness and fineness by putting a sheet of luminous body consisting of a bonding agent and a stimulable phosphor on a support and contacting them by pressing with a calender roll at the temperature above the softening temperature of the bonding agent. CONSTITUTION:After preliminary heating of a layer body 15 made of a sheet 13 of luminous body consisting of a bonding agent and a stimulable phosphor and a support 14, by a heater 12, they are contacted by pressing with calender rolls 11A, 11B at the temperature above the softening or melting temperature of the bonding agent.

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 the conventional radiographic method, there is a radiation image conversion method using a stimulable phosphor as described in, for example, Japanese Unexamined Patent Publication No. 55-12145. It has been 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,
When the content of phosphor in the phosphor layer is constant, the denser the phosphor particles are packed, the thinner the layer thickness can be, which reduces the spread of excitation light due to scattering. , 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 1 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) Step of forming a phosphor sheet consisting of a binder and a stimulable phosphor, b) placing the phosphor sheet on a support, heating the obtained laminate, and then further heating or A method for producing a radiation image conversion panel, comprising the step of adhering a phosphor sheet onto a support by pressurizing and compressing it at a temperature equal to or higher than the softening temperature or melting point of the binder while keeping it warm. This is what we provide.

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 adhesion 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.

In addition, in the present invention, the laminate of the phosphor sheet and the support is first preheated, and then compressed and bonded using a calender roll (in this case, the roll of the calender roll is heated and the laminate is preheated. The laminate is compressed at a temperature above the softening or melting point of the binder, either by further heating or by keeping the preheating temperature warm, so that the laminate passes through the calender rolls at high speed. It is compressed when it is sufficiently heated. Therefore, for example, if the roll of a calendar roll is heated without preheating, and the laminate is heated only at the same time as compression bonding (in this case, it takes time for the laminate to be sufficiently heated). Therefore, the production amount per unit time is also high compared to the case where the roll has to be passed through the roll at a relatively slow speed.

Preferred embodiments of the present invention are listed below.

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

(2) The binder has a softening temperature or 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 softening temperature or melting point of the binder is 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 above 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 manufacturing a radiation image storage panel, characterized in that the pressure treatment in step b) is performed using a combination of two or more pairs of calender rolls.

(7) A radiation image conversion panel characterized in that the pressure treatment in step b) above is performed using a combination of two or more pairs of calender rolls, and heating is performed at least at one location in front of each pair of rolls. manufacturing method.

(8) A method for producing a radiation image conversion panel, characterized in that the heating in step b) is performed by at least one heater selected from the group consisting of a far-infrared heater, a heat roller, and a hot air heater.

[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 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 to form a laminated layer. A step of adhering the phosphor sheet onto the support by heating the body and then pressing and compressing it at a temperature equal to or higher than the softening temperature or melting point of the binder while further heating or keeping it warm using a calender roll. It has become.

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
B, O,: Cu, Ag, Li2 described in JP-A-54-47883
O・(B202)X: Cu and Li2O・(B202
), : Cu, Ag, SrS:Ce, Sm, SrS:Eu as described in U.S. Pat. No. 3,859,527.

Sm, The□: Er, and La2O2S: E
u, Sm1 ZnS described in JP-A-55-12142
: Cu, Pb, BaO-xAf□03:Eu (however, 0.8≦X≦10), and M I I Q x
sio2: A (However, M” is Mg, Ca, Sr, Z
n, Cd, or Ba, and A is Ce, Tb, Eu,
Tm, Pb, Tj2, Bi, or Mn, and X is
0.5≦X≦2.5), as described in JP-A-55-12143 (
a 1-x-y 1M g x , Ca y )
F X : aE u ” (where X is at least one of CI and Br, and
<x+y≦0.6 and xy≠0, and a is 10−
6≦a≦5X10-2), LnO described in JP-A-55-12144
X: xA (Ln is at least one of La, Y, Gd, and Lu, X is CIL and Br
A is at least one of Ce and Tb, and X is 0<x<0.1), as described in JP-A-55-12145 (Ba
,,,M") FX: yA (However, M" is M
At least one of g, Ca, Sr, Zn, and Cd, X is at least one of CJ2, Br, and I, A is Eu, Tb, Ce, Tm, Dy, Pr, Ho
, Nd, Yb, 8, and Er, where X is 0≦X≦0.6 and y is 0≦y≦0.2), JP-A-55-843897 Ba listed in the official gazette
FX: Phosphor expressed by xCe, yA JP-A-1983-
M-th FX-xA described in Publication No. 160078
: yLn [However, M" is Ba, Ca, Sr%M
at least one of g, Zn, and Cd, A is B
e01Mg01CaO,5rO1B a O,Z n
O, A Rz 03 , Y2O3, La2O3, In
2O3, SiO2, TiO□, ZrO2, GeO2, S
At least one of nO2, Nb2O5, Ta2o5, and TaO2, Ln is Eu, Tb, Ce, Tm,
Dy, Pr, Ho, Nd, Yb, Er, Sm,
and at least one of Gd, X is CIl, Br
, and at least one of ■, and X and y
are 5X10-5≦X≦0.5 and o<y≦, respectively.
A phosphor represented by the composition formula of
al-x, M”X) F2-a BaX2
: yEu, zA [However, M” is helillium,
at least one of 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, S and 2 are each 0.5≦a≦1.2
5.0≦X≦1.10-6≦y≦2X10-', and O<z≦10-2] A phosphor is described in JP-A-57-23673. There is (B
at-x, Mth) F2-aBaX2:yEu,
zB [However, M'' is at least one of helium, magnesium, calcium, strontium, zinc, and cadmium, X is at least one of chlorine, bromine, and iodine, and a, x, y, and Z are 0.5≦a≦1.25.0≦X≦1.10-6, respectively
≦y≦2×10−1, and O<z≦2×1O−’] A phosphor is described in Japanese Patent Application Laid-Open No. 57-23675 (“a
l-X 9M”x) F2 ・a BaX2:
yEu, zA [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 is at least one of arsenic and silicon. species, a, x, y, and Z are each 0.5≦a≦1.25.0≦X≦1, to-'≦
A phosphor represented by the following compositional formula where y≦2X10-' and 0<z≦5X10-', M"' described in JP-A-58-69281
OX: xCe [However, M port 1 is PrNd%P
m, 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.
Either or both of these, and X is 0
A phosphor represented by the composition formula <x<0.1], Ba described in JP-A No. 58-206678
n-X MX, 2Lx/2 FX: yEu'' [M represents at least one alkali metal selected from the group consisting of Li, Na, Rh, and Cs;
L is Sc, Y, La, Ce, PrNd, Pm, Sm,
Gd, Tb, Dy, Ho.

Er, Tm, Yb, Lu, Al1, Ga, In,
and T1; X represents at least one halogen selected from the group consisting of CM, Br, and ■; and X represents 0-2≦X≦ 0.5, y is o<y≦0,1, a phosphor represented by the composition formula BaF described in JP-A No. 59-27980.
X −xA: yEu” [where X is Cll, 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] XM3 described in JP-A No. 59-38278
(PO4)2-NX2:3'A, M3(PO4)2:y
A and nReX3-mAX'2: xEu, nReX
, -mAX'2: xEu, ySm, M'X -aM
"X'・bM"'X"3: Phosphor represented by cA, BaFX described in JP-A No. 59-47289
-xA: yEu'' [where, X is at least one kind of halokene selected from the group consisting of C1, Br, and I; A fired product of at least one compound selected from the group of hexafluoro compounds consisting of salts of monovalent or divalent metals:
And, X is 10-6≦X≦0.1, and y is o<y≦0.
A phosphor represented by the composition formula 1], JP-A-59-
BaFX-xNaX described in Publication No. 56479
':aEu' [Tatashi, X and Xo are each C1
1, Br, and I;
and a are 0<x≦2 and 0<a≦0.2, respectively
A phosphor represented by the composition formula of
X-xNaX':yEu": zA [The Mth is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca, and and at least one halogen selected from the group consisting of I; A is V, Cr,
is at least one transition metal selected from Mn, Fe, Co, and Ni: and X is 0<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" -cM
ll+X"' -xA: yEu" [However, M"
is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr, and Ca, and MT is Li, N
a, Rh, and Cs; M'' is at least one divalent metal selected from the group consisting of Be and Mg; M'' is Al1. at least one trivalent metal selected from the group consisting of Ga, In, and Tj2; A is a metal oxide; X is CI2. Br, and I
X', X" and X" are at least one halogen selected from the group consisting of F, CIL, Br, and I; and a is 0≦ a≦2, b is O≦b≦10-2
, C is 0≦C≦10-2, and a+b+c≧10-6; X is O<x≦0.5, y is o<y≦0.2]. , M”X described in Japanese Patent Application Laid-Open No. 60-84381
2- aM"X': xEu" [t, M" is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; X and X' are Ca
, Br, and I, and X≠X': and a is 0.1≦a≦10.0, and X is 0<x≦0.2. ] A stimulable phosphor represented by the composition formula M" described in JP-A-60-101173
FX -aM'X':xEu" [However, M"
is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr and Ca; M' is at least one kind of alkali metal selected from the group consisting of Rb and Cs; X is selected from CI2, Br and I; at least one species of halogen selected from the group; x' is F, C
11, Br, and I; and a and X are 0≦a≦4.0 and 0<x≦02, respectively. Exhaustible phosphor, M'X described in JP-A No. 62-25189
:xBi [where 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 C2, Br and I; and X is O<x A stimulable phosphor represented by the composition formula [with a numerical value in the range of ≦0.2],
etc. can be mentioned.

In addition, the M"X2- a M"
It may be contained in the following proportions per mole of M"X'.

bM described in JP-A-60-166379
"X" (where Ml is at least one alkali metal selected from the group consisting of Rh and Cs,
” is at least one kind of halogen selected from the group consisting of F, CI2, Br and summer, and b is o<b≦
1O90): b described in JP-A No. 60-221483 is X"-cMgX"°・dMllll
X"" (Tat, M"' is at least one trivalent metal selected from the group consisting of Sc, Y, La, Gd and Lu, and X", X"° and X" are all F, Ca
, Br and I, and s, c and d are each,
0≦b≦2.0, O≦C≦2.0.0≦d≦2.0, and 2XlO-5≦b+c+d); described in JP-A-60-228592 yB (where y is 2X10-'≦y≦2X10-'): bA described in JP-A-60-228593 (however, A is selected from the group consisting of SiO2 and P2O5) It is at least one kind of oxide, and when dried, b is 10-
4≦b≦2xlO-'; JP-A-61-1208
bSiO described in Publication No. 83 (where b is o<b
bSnX”2 (where X' is at least one halogen selected from the group consisting of F, C1!, Br and I); , and b is o<bSiO
-3): bCsX"-cSnX"' (However, X"
and X″′ are each at least one kind of halogen selected from the group consisting of F, Cl3, Br and 1,
b and C are respectively 0〈bSiO,0 and 10-6≦C≦2xlO-2), and JP-A No. 6
bCsX” described in Publication No. 1-235487
y L n 3+ (However, X" is at least one kind of halogen selected from the group consisting of F, Cn, Br and I, and Ln is Sc, Y%Ce, Pr, Nd, Sm, G
d, TbDy, Ho, Er, Tm, Ybj, 5 and Lu
at least one rare earth element selected from the group consisting of, and b and y are respectively o<bSiO,
0 and 10-6≦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. There may be.

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; acetone, methyl ethyl ketone, and methyl isobutyl ketone. Ketones: Esters of lower fatty acids such as methyl acetate, ethyl acetate, and butyl acetate and lower alcohols; 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 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 butyl glycolate, etc. Glycolic acid esters: Examples include 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, 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, the process P in the method for manufacturing a radiation image conversion panel of the present invention
Let's talk about 1b).

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, or is preferably a support made of plastic.

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 oxide, or a light-absorbing substance such as carbon black. It is known to provide a light absorption layer or the like. The support used in the present invention can also be provided with various stiff layers, and the structure thereof 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), the phosphor sheet produced as described above is placed on the support to form a laminate, the laminate is preheated with a heater, and then bonded with a calendar roll while being further heated or kept warm. This is a process of compressing the phosphor sheet at a temperature higher than the softening temperature or melting point of the agent and adhering (bonding) it onto the support.

Hereinafter, this step b) will be explained in detail with reference to the attached drawings.

FIGS. 1(a) to 1(d) are diagrams schematically showing how step b) of the present invention is performed in each embodiment. In FIG. 1(a), a laminate 15 of a phosphor sheet 13 and a support 14 is preliminarily heated by a heater 12, and then heated (or kept warm), compressed, and bonded by calender rolls IIA and IIB. Ru. As this heater 12, for example, a far infrared heater or a hot air heater is used. In FIG. 1(a), the heater 12 is placed on the side of the phosphor sheet 13 and on the side of the support 14.
Although the laminate 15 is heated from both sides, it is of course possible to heat only from one side.

Further, as shown in FIG. 1(b), two or more pairs of calender rolls may be used to perform two or more stages of compression. That is, in FIG. 1(b), the laminate 25 of the phosphor sheet 23 and the support 24 is preheated by the first stage heater 22, and is heated by the first stage calender roll (referred to as the - next roll). ) 21A and 21B heat (or keep warm) and pressurize. Subsequently, this laminate 25 is heated by the second stage heater 22°,
Second stage calendar roll (referred to as secondary roll) 21
'A, 21' B is pressurized to complete the compression bonding.

In the case of FIG. 1(b), as in the case of FIG. 1(a), the heaters 22, 22'' do not necessarily have to be on both sides of the laminate 25, but on either the phosphor sheet 23 side or the support 24 side. However, when using two or more stages of calender rolls as shown in FIG. 1(b), it is preferable to preheat at least one place in front of each stage of calender rolls.

The heater for preheating the laminate is not limited to a far-infrared heater or a hot air heater such as 12.22 shown in FIG.
A beat roller as shown in C) and (d) may also be used.

That is, in FIG. 1(c), the laminate 35 is exposed to the phosphor sheet 33 by the contact heat generated by the beat roller 32.
The calender roll 3 is heated from both sides of the support 34.
1A and 31B are compression bonded. of course,
In this case as well, the beat rollers do not necessarily have to be on both sides of the laminate 35, but may be on either the phosphor sheet 33 side or the support 34 side.

An embodiment in which two-stage compression is performed using a beat roller as a heater is shown in FIG. 1(d). In this case too,
As in the case of (b), the heaters 42 and 42' do not necessarily have to be on both sides of the laminate 45, but rather
It may be on either the side or the support 44 side, but it is preferable to heat at least one place in front of the calender roll at each stage.

Preheating with a heater starts from a temperature where the temperature of the phosphor sheet is 20°C lower than the softening temperature or melting point of the binder.
It is preferable that the temperature be increased by 0°C.

The pressure of the calender roll is 50 kgw/cm2 when compressing only one stage as shown in Fig. 1 (a) and (c).
In the case of two stages as shown in Fig. 1(b) and (d), the secondary roll is 10 to 1000 kgw/cm2 and the secondary roll is 50 to 2000 kgw/cm2.
A pressure of 2 is appropriate.

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. As mentioned above, a calender roll usually consists of a pair of rolls (a combination of a metal 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 sheet-like laminate of the phosphor sheet and the support produced in step a) is processed by passing it between a pair of rolls under pressurized conditions.

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

Vair/'/ (a+b) p. 9 y V A (apy”
bρX )V[(a+b)pXpy −apy pai
r -tlx ρair] (Tap, V: Total volume of the phosphor layer Vair: Air volume in the phosphor layer A: Total weight of the phosphor layer ρ8: Density of the phosphor ρy: Density of the binder pair: Air Density a : weight of phosphor b = weight of binder) Furthermore, in formula (I), pair is approximately 0, so formula (I) can be approximately expressed by formula (II) below.

Vair/V= (a”b)px ρy V A (apy ” b9
x ) (II) (Tatashi, V, Vair, A, ρ8, ρ2, a,
The definitions of and b are the same as in equation (1)) Furthermore, the filling rate of the phosphor can be determined by the following equation (Illr).

Margin below V [(a+b)ρ. ρy] AaρAV [(a”b) p X ρy ] (m)
The definitions of a and b are the same as in formula (1)) In a normal radiation image conversion panel, a phosphor layer is placed 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 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. The phosphor layer can be formed by coating the surface of the phosphor layer with a solution prepared by dissolving a polymeric substance in an appropriate solvent. Or a plastic sheet 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, in order to improve the sharpness of the resulting 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 (see Japanese Patent Publication No. 5'123400).

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 9101: Eu”
200 g Binder: Polyurethane elastomer (Bayer Urethane Desmolac TPKL-5-
2625 [solid content 40%]) 22.5g of anti-yellowing agent, epoxy resin (oiled shell epoxy ■ Epicoat 1007) was added to a 1:1 mixed solvent of methyl ethyl ketone and 2-propanol, and mixed with a propeller mixer. Dispersed, viscosity is 30P
A coating solution of S (25°C) was prepared (binder/phosphor ratio =
1/20). This is a polyethylene terephthalate sheet (temporary support, thickness 1
After drying, the binder is peeled off from the temporary support to form a phosphor sheet. Vicat softening temperature of the binder is 45° C. [ASTM D1525]).

On the other hand, as a coating liquid for forming a light reflective layer, BaFBr (containing 90% particles with a particle size in the range of 1 to 5 μm), 214 g of soft acrylic resin, solid content of 25.7 g of epoxy resin
10.7g nitrocellulose (nitrification degree 11.5
%, solid content 10% by weight) 64g,
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).

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. An undercoat layer was formed on the support (thickness of coating film = 15 μm). Further, 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 heated and compressed at a feeding speed of 2 m/min using a pair of calender rolls and a far-infrared heater as shown in Figure 1 (a) of the attached drawings. processed.

A thermocouple (measurement error: ±t o"c) was inserted into the phosphor sheet to measure the temperature inside the sheet just before compression, and it was 70°C. The pressure of the calender roll at this time was 600 kg w. /cm2.

By the above heating and compression treatment, the phosphor sheet and the light reflection layer on the support were completely fused together, and the thickness of the phosphor sheet (phosphor layer) was 175 μm.

After this heating and compression 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 pressure of the calender roll was 500 kg w/c
tn”, a phosphor sheet (
Example I except that the thickness of the phosphor layer was 185 μm.
A radiation image storage panel was manufactured in exactly the same manner as A.

[Comparative Example 1] In FIG. 1(a), the example was the same except that the heating compression treatment was performed at a feed rate of 2 m/min by heating the support side roll IIB without turning on the far-infrared heater 12. A radiation image storage panel was manufactured in the same manner as in Example 1.

[Comparative Example 2] In FIG. 1(a), the example was the same except that the heating compression treatment was performed at a feed rate of 2 m/min by heating the support side roll IIB without turning on the far-infrared heater 12. A radiation image conversion panel was manufactured in the same manner as in Example 2.

[Comparative Example 3] A radiation image conversion panel was manufactured in the same manner as in Comparative Example 1 except that the feeding speed was 0.2 m/min.

[Comparative Example 4] A radiation image conversion panel was manufactured in the same manner as in Comparative Example 2, except that the feeding speed was 0.2 m/min.

The image quality of the radiation image conversion panels obtained in Example 1.2 and Comparative Examples 1.2.3 and 4 of Paul's was evaluated by the method described below.

That is, each radiation image conversion panel has a tube voltage of 80 KVp.
After irradiating with X-rays, He-Ne laser light (632
. Obtained. The modulation transfer function (MTF) of the obtained image (
The sharpness was measured by spatial frequency = 2 cycles/mm) and the graininess (RMS) at doses of 0, 1 mR.

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

In Figure 2, the vertical axis shows sharpness (spatial frequency 2 cycles/
MTF value at mm) is taken, 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. 2, the radiation image conversion panel manufactured according to the present invention exhibits superior image quality to the radiation image conversion panels of comparative examples (Comparative Examples 1 and 2) manufactured at the same feed speed. In addition, if you try to obtain an image quality equivalent to that of the present invention using the method of the comparative example, it will be 1/1 of that of the manufacturing method of the present invention.
It was found that it had to be manufactured at a feed rate that was 10 times slower.

[Brief explanation of drawings]

FIGS. 1(a) to 1(d) are schematic diagrams showing several systems used for manufacturing the radiation image storage panel of the present invention. FIG. 2 is a graph showing the image quality of radiation image conversion panels according to Examples and Comparative Examples. 11A, IIB, 21A, 21B, 31 A13
1B, 41A, 41B: Calendar rolls 12, 22,
22' 32, 42, 42': Heater 13.23.33.43: Phosphor sheet 14.24.3
4.44: Support 15.25.35.45: Laminate patent applicant Fuji Photo Film Co., Ltd. Agent Patent attorney Yasushi Yanagawa 10-2 Graininess (RMS) (a) (C) Figure ( b)

Claims (1)

[Scope of 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. a) forming a phosphor sheet made of a binder and a stimulable phosphor; b) placing the phosphor sheet on a support, heating the resulting laminate, and then rolling it with a calender roll. A radiation image storage panel characterized by comprising the steps of: adhering the phosphor sheet onto the support by pressurizing and compressing the binder at a temperature higher than the softening temperature or melting point of the binder while further heating or keeping it warm. manufacturing method.