JPH02193100A - Radiation image conversion panel - Google Patents

Abstract

PURPOSE:To endure repeated use to obtain a radioactive conversion panel without deterioration of sensitivity by forming the protection layer of a radiation image conversion panel having a phosphor layer and protection layer with the use of an application film containing fluorocarbon resin of organic solvent solubility. CONSTITUTION:As for a phosphor layer, for instance, an accelerated phosphor and a binding agent are added into a proper solvent to mix it so as to prepare application liquid in which the accelerated phosphor is uniformly scattered in a binding agent solution. After a prepared phosphor is uniformly applied to the surface of a supporter, it is dried. As for a protection film, a protection film formation material application liquid containing fluorocarbon resin of organic solvent solubility is uniformly applied to the surface of the phosphor with the use of a doctor blade and the like to dry. As fluorocarbon resin, for example, a polymer and the like of olefin containing fluorine are mentioned and its content is about 30% or more, preferably 50% or more, and furthermore 70% or more.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to 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 utilizes a radiographic panel (also referred to as a stimulable phosphor sheet) containing a photostimulable phosphor, and uses radiation transmitted through or emitted from the subject to be detected by the panel's photostimulable phosphor. The stimulable phosphor is absorbed by the phosphor, and then the stimulable phosphor is excited by electromagnetic waves (excitation light) such as visible light or infrared rays in a time-series manner, so that it 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 the radiation image of the subject or subject as a visible image based on the obtained electrical signal. It is.

On the other hand, after the reading is completed, the remaining image is erased from the panel, and then the panel is prepared for the next photographing. That is, the radiation image conversion panel is used repeatedly.

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. Furthermore, in contrast to conventional radiography, which consumes radiographic film for each imaging session, this radiographic image conversion method uses the radiographic image conversion panel repeatedly, which is advantageous in terms of resource conservation and economic efficiency. It is.

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 the surface of the support, but if the phosphor layer is self-supporting, the support is not necessarily required.

The stimulable phosphor layer includes not only a stimulable phosphor layer and a binder that contains and supports the stimulable phosphor in a dispersed state, but also a layer that does not contain a binder and is formed by a vapor deposition method or a sintering method. One that is composed only of aggregates of stimulable phosphor is known. Additionally, the applicant has already filed a patent application for a radiation image conversion panel having a stimulable phosphor layer in which the gaps between stimulable phosphor aggregates are impregnated with a polymeric substance (Japanese Patent Application No. No. 96803). In any of these phosphor layers, the stimulable phosphor has the property of exhibiting stimulated luminescence when irradiated with excitation light after absorbing radiation such as X-rays. The radiation emitted from the specimen is absorbed by the stimulable phosphor layer of the radiation image conversion panel in proportion to the radiation dose, and a radiation image of the subject or subject is formed on the panel as an image of accumulated radiation 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.

Generally, a protective film is provided on the surface of the stimulable phosphor layer opposite to the support (the surface not facing the support) to protect the phosphor layer from chemical alteration or physical damage. Protects from strong impacts.

The protective film can be formed by coating the phosphor layer with a solution prepared by dissolving a transparent organic polymer material such as a cellulose derivative or polymethyl methacrylate in an appropriate solvent, or a film made of polyethylene. A protective film-forming sheet such as an organic polymer film such as terephthalate or a transparent glass plate is formed separately and attached to the surface of the phosphor layer using an appropriate adhesive, or a phosphor layer is formed by vapor-depositing an inorganic compound. A film formed on a layer is known.

Among these, protective films formed by coating generally have strong adhesive strength with the phosphor layer and have the advantage that they can be manufactured through relatively simple steps. In particular, as previously filed by the applicant, a radiation image storage panel having a protective film formed at the same time as the phosphor layer by simultaneous multilayer coating has a higher adhesion between the protective film and the phosphor layer than conventional panels. It not only has high strength but also excellent sensitivity and image quality (see Japanese Patent Application Laid-Open No. 61-61100 and Japanese Patent Application Laid-open No. 80100-1982).

By the way, in implementing the radiation image conversion method, the radiation image conversion panel is used for radiation irradiation (recording the radiation image), excitation light irradiation (reading the recorded radiation image), and erasing light irradiation (remaining radiation image recording). It is used repeatedly in a cycle called "erasure". The movement of the radiation image conversion panel to each step is carried out by a conveying means such as a belt or roller, and after the cycle is completed, the panels are usually stacked and stored. However, when a radiation image storage panel having a protective film formed by coating as described above is used repeatedly in this manner, the sensitivity of the panel may gradually decrease.

Like the intensifying screen used in conventional radiography, the radiation image conversion panel is also desired to have high sensitivity and provide images with good image quality (sharpness, granularity, etc.). Preventing the decrease in sensitivity as described above is an important issue.

[Summary of the Invention] An object of the present invention is to provide a radiation image conversion panel having a protective film formed by coating, which does not cause a decrease in sensitivity even when used as a green coating. .

The above object is to provide a radiation image storage panel of the present invention having a phosphor layer made of a stimulable phosphor and a protective film, in which the protective film is formed of a coating film containing a fluororesin soluble in an organic solvent. This can be achieved by a radiation image conversion panel characterized by being a membrane.

However, the fluororesin herein refers to a polymer of an olefin containing fluorine (fluoroolefin) or a copolymer containing an olefin containing fluorine as a copolymer component.

Further, the film formed by the coating film of the above-mentioned fluororesin may be crosslinked.

As a result of researching the cause of the above-mentioned decrease in sensitivity, the inventor of the present application found that
We have discovered that the cause of this problem is that plasticizers seeping out from conveying members such as belts and rollers contaminate the surface of the panel's protective film that comes into direct contact with these conveying members. The present invention has been made based on this knowledge.

In other words, since conveyance members such as the belts and rollers mentioned above are generally made of materials such as rubber or plastic containing plasticizers, when the radiation image conversion panel is conveyed, there is no possibility of seepage from the belts or rollers. The plasticizers and the like contaminate the surface of the panel's protective film that comes into direct contact with these conveying members. Normally, readout of a radiation image conversion panel by irradiation with excitation light is performed from the surface on the protective film side, so dirt on the surface of the protective film prevents the passage of excitation light and stimulated luminescence light during readout, resulting in a decrease in sensitivity. bring about.

However, the conventional protective film made of an organic polymer material formed by coating has the disadvantage that the dirt caused by the above-mentioned conveying member seeps into the inside of the protective film and cannot be removed by wiping or the like.

Therefore, the radiation image conversion panel of the present invention is difficult to absorb stains caused by plasticizers exuding from conveying members such as belts and rollers, and stains attached to the surface can be easily removed by wiping. This is a radiation image conversion panel having a protective film formed by.

A protective film made of a fluororesin does not allow stains such as plasticizers exuding from conveying members such as belts and rollers to penetrate into the inside of the protective film, so the stains can be easily removed by wiping or the like.

The radiation image conversion panel of the present invention uses a fluororesin soluble in an organic solvent as a material for forming a protective film, so it can be easily prepared by dissolving this resin in an appropriate solvent, applying a solution prepared and drying. Can be formed into a film.

Preferred embodiments of the present invention are listed below.

(1) The above fluororesin is at least one fluororesin selected from the group consisting of a copolymer containing a fluoroolefin as a copolymer component, polytetrafluoroethylene, and polytetrafluoroethylene. Characteristic radiation image conversion panel.

(2) The fluororesin is at least one fluororesin selected from the group consisting of a copolymer of fluoroolefin and vinyl ether, polytetrafluoroethylene, and modified polytetrafluoroethylene. A radiation image conversion panel.

(3) A radiation image storage panel, wherein the fluororesin is at least one fluororesin selected from the group consisting of a copolymer of fluoroolefin and vinyl ether and a modified polytetrafluoroethylene.

(4) A radiation image storage panel, wherein the fluororesin is a copolymer of fluoroolefin and vinyl ether.

(5) A radiation image storage panel, wherein the fluororesin is polytetrafluoroethylene or a modified product thereof.

(6) A radiation image conversion panel characterized in that the fluororesin component in the protective film is 30% by weight or more.

(7) A radiation image storage panel characterized in that the fluororesin component in the protective film is 50% by weight or more.

(8) The fluororesin component in the above protective film is 70fi%
A radiation image conversion panel characterized by the above.

(9) A radiation image storage panel characterized in that the fluororesin in the protective film is crosslinked.

[Configuration of the Invention] The radiation image conversion panel of the present invention will be described in detail below.

First, the stimulable phosphor constituting the phosphor layer of the radiation image conversion panel of the present invention will be described.

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, a phosphor that exhibits stimulated luminescence in a wavelength range of 300 to 500 nm by excitation light in a wavelength range of 400 to 900 nm is desirable. Examples of stimulable phosphors used in the radiation image storage panel of the present invention include SrS:Ce, Sm, and SrS:Eu, which are described in US Pat. No. 3,859,527.

Sm, The□: Er, and La2O2S: Eu
, Sm.

ZnS described in Japanese Patent Application Laid-Open No. 55-12142
: Cu, Pb, Ba0-xAl2O3:Eu (however, 0.8≦X≦10), and M"O-xS i
O7:A (However, M'l is Mg.

Ca, Sr, Zn, Cd, or Ba, and A is Ce
, Tb, Eu, Tm, Pb, Tl, Bil or Mn, and X is 0.5≦X≦2.5), as described in JP-A-55-12143 (B
a l -X-y, Mgx, Ca, ) FX:
aEu 2 + (However, X is at least one of CI and Br, and X and y are o<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 La, Y.

At least one of Gd and Lu, X is at least one of C1 and Br, A is Ce and Tb
and X is 0<x<0.
1), described in JP-A-55-12145 (Ba
t-111M"X) F X : yA (M" is at least one of Mg, Ca, Sr, Zn, and Cd, Eu, Tb, Ce, Tm, Dy
, Pr, Ho, Nd%Yb, and Er; X is 0≦X≦0.6; y is
0≦y≦0.2), M” described in JP-A-55-160078
FX -xA: yLn [However, M" is Ba, C
a, at least one of Sr, Mg, Zn, and Cd, A is Be05Mg01CaO1SrOSBaO1
ZnO%AIl, 03, Y.

03, La203. In203.5i02, TiO2,
ZrO2, Gem2.5n02, Nb2O5, Ta
20 at least one of r, s and The2, LnldEu, Tb, Ce, Tm, Dy, Pr,
At least one of Ho, Nd, Yb, Er, Sm, and Gd, X is at least one of C1, Br, and I, and X and y are each 5x
lO-'≦X≦0.5, and o<y≦0.2]
The phosphor represented by the composition formula is
at-x, MII, 1) F2 ・aBaX2:yE
u, 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 zirconium and scandium. It is a kind of a, x, y,
and Z are respectively 0.5≦a≦1.25.0≦X≦1
．． 10-6≦y≦2XIO-' and 0<z≦10
-2] Phosphor represented by the composition formula, JP-A-57
-23673 (Ba,...,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 2 are each 0.5
≦a≦1.25.0≦X≦1.10-6≦y≦2×10
-1, and O<z≦2
,,M eyes)F2-aBaX,: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, A is at least one of arsenic and silicon, a, x, y, and 2 are each 0.5
≦a≦1.25.0≦X≦1.10-6≦y≦2X10
A phosphor represented by the composition formula "" and O<z≦5X10-', M"' described in JP-A-58-69281
OX: xCe [However, M1■ is Pr, Nd%
Pm, 3m%Eu, Tb, Dy, Ho, Er, Tm,
At least one trivalent metal selected from the group consisting of Yb and Bi, X is either one or both of Cf2 and Br, and X satisfies O<x<0.
A phosphor represented by the composition formula of
t-X M)l/2 LX/2 FX: yEu”[
However, M represents at least one alkali metal selected from the group consisting of Li, Na, Rb, g, and Cs; L represents Sc, Y, La%Ce, PrNd%Pm,
Sm, Gd, Tb, Dy, Ho.

Er, 7m%Yb, Lu, Al,, Ga, I
represents at least one type of trivalent metal selected from the group consisting of n, and Tu; X represents at least one type of halogen selected from the group consisting of C1l, Br, and 1; and X represents 10-2≦X ≦0. 5y is o<y≦
A phosphor represented by the composition formula of
X-xA: yEu” [However, X is Cff1.B
r, and at least one kind of halogen selected from the group consisting of ■; zA 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] BaF described in JP-A-59-47289
X −xA: yEu” [However, X is.

Cf2. Br, and at least one kind of halogen selected from the group consisting of summer; and X is 10-6≦X≦o, 1.
y is o<y≦0.1] A phosphor B described in JP-A No. 59-56479
aFX −xNaX′:aEu” [where X and
a phosphor represented by the composition formula: o is at least one of Cl, Br, g and I, and X and a are O<x≦2 and 0<a≦0.2, respectively; M”F described in Japanese Patent Application Laid-Open No. 59-56480
X −xNaX':yEu": zA [However, M"
is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca;
are 5 respectively C1 and Br.

and A is at least one type of halogen selected from the group consisting of; A is at least one type of transition metal selected from V, cr, Mn, FeCO1, and Ni;
and phosphor represented by the composition formula: M”F listed in the official gazette
X-aM'X'-bM'"X"2"cMllll
xl, XA: yEu” [However, M” is Ba,
is at least one kind of alkaline earth metal selected from the group consisting of Sr and Ca, and Mt is Li, Na,
, Rh, and at least one alkali metal selected from the group consisting of Cs; M"1 is Be and Mg
is at least one divalent metal selected from the group consisting of; M'' is at least one trivalent metal selected from the group consisting of Ga, In, and TIL; A is a metal oxide; ;X is at least one halogen selected from the group consisting of Cfl, Br, and I;
'x'' and x'' are at least one kind of halogen selected from the group consisting of F, Cft, Br, and I: and a is 0-≦a≦2b is 0≦b≦10-'
c is 0≦C≦1O-2, and a+b+c≧10-8; X is 0<x≦0.5, y is o<y≦0.2]
A phosphor represented by the composition formula M”X described in JP-A No. 60-84381
2- aM"X',: xEu" [However, M" is B
a, at least one alkaline earth metal selected from the group consisting of Sr and Ca; X and X' are Cl2
, Br, and I, and X#X'; and a is 0.1≦a≦10.0, and X is O<x≦0.2. A stimulable phosphor represented by the compositional formula of at least one alkaline earth metal selected from the group; Ml is Rb and C
at least one alkali metal selected from the group consisting of s; X is at least one halogen selected from the group consisting of cIL, Br and I; xo is F, C
l3. at least one halogen selected from the group consisting of Br and I; and a and X are each 0
A stimulable phosphor represented by the composition formula: ≦a≦4.0 and 0<x≦0.2, M' described in JP-A-62-25189
X:xBi [where Ml is at least one alkali metal selected from the group consisting of Rh and C8:
X is at least one halogen selected from the group consisting of C2, Br and 1; 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, the M"X2 .aM"X' 2 :xEu2+ stimulable phosphor described in the above-mentioned Japanese Patent Application Laid-open No. 60-84381 contains the following additives M"X2 .
It may be contained in the following proportions per aM"X' 21-1-7L/per.

bM described in JP-A-60-166379
lx" (However, Ml is at least one kind of alkali metal selected from the group consisting of Rh and Cs, and X"
is at least one kind of halogen selected from the group consisting of F, CIl, Br and 1, and b is o<b
≦10.0); bKX"-CMgX"2-dM"' described in JP-A No. 60-221483
X"3 (However, 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 both F.

At least one halogen selected from the group consisting of Cm, Br, and summer, and s, c, and d are each O≦b≦2.0.0≦C≦2゜0.0≦d≦2.0
and 2X10"'≦b+c+d); yB(
However, y is 2XIO-'≦y≦2X10-')
; b described in Japanese Patent Application Laid-Open No. 60-228593
A (However, A is at least one kind of oxide selected from the group consisting of SiO2 and P2O5, and b is 10-4≦b≦2X10-''): JP-A-61
- bSin described in Publication No. 120883 (however, b is o<b≦3X10-2); JP-A-61-
bSnX"2 (
However, X" is at least one kind of halogen selected from the group consisting of F, Cl2, Br and I, and
is o<b≦10′″3): JP-A-81-2354
bCsX"/cSnX" (described in Publication No. 86)
However, X'' and Xl are each at least one kind of halogen selected from the group consisting of F, CIL, Or, and I, and b and C are each o<b≦10
．． 0 and 1O-6≦C≦2×10-2); and b described in JP-A-61-235487.
CsX" y L n 31"(X" is F%
At least one halogen selected from the group consisting of C1l, Br field and I, Ln is Sc% Y, Ce, P
r, Nd, Sm.

Gd%Tb, Dy1Ho, Er, Tm, Yb and Lu
at least one rare earth element selected from the group consisting of, where b and y are o<b≦10.0 and 10-6≦y≦1.8×10-1, respectively).

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

The stimulable phosphor layer of the radiation image storage panel of the present invention is not only composed of a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state, but also a stimulable phosphor layer without a binder. It may be a phosphor layer composed only of phosphor aggregates, or a phosphor layer in which gaps between stimulable phosphor aggregates are impregnated with a polymeric substance.

The method for manufacturing the radiation image storage panel of the present invention will be described below, taking as an example the case where the phosphor layer is composed of a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state.

The phosphor layer can be formed on the support, for example, by the following method.

First, the above-mentioned stimulable phosphor and binder are added to a suitable solvent and thoroughly mixed to prepare a coating solution in which the stimulable phosphor is uniformly dispersed in the binder solution.

Examples of binders for the phosphor layer include proteins such as gelatin,
Polysaccharides such as dextran, or natural polymers such as gum arabic: and polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, vinylidene chloride/vinyl chloride copolymer, polyalkyl (meth)acrylate, vinyl chloride/vinyl acetate Binders typified by synthetic polymeric materials such as copolymers, polyurethanes, cellulose acetate butyrate, polyvinyl alcohol, linear polyesters, etc. may be mentioned. Particularly preferred among such binders are nitrocellulose, linear polyester,
These are polyalkyl (meth)acrylates, polyurethanes, mixtures of nitrocellulose and linear polyesters, and mixtures of nitrocellulose and polyalkyl (meth)acrylates.

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

The support can be arbitrarily selected from materials known as supports for conventional radiation image storage panels. Examples of such materials include films of plastic substances such as cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, polycarbonate, metal sheets such as aluminum foil, aluminum alloy foil, regular paper, baryta paper, resin. Examples include coated paper, pigment paper containing pigments such as titanium dioxide, paper sized with polyvinyl alcohol, and plates or sheets of ceramics such as alumina, zirconia, magnesia, and titania.

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 their configurations 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).

After forming the coating film on the support as described above, the coating film is dried to complete the formation of the stimulable phosphor layer on the support. The thickness of the phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the type of phosphor, the mixing ratio of the binder and the phosphor, and is usually 20 μm to 1 mm.

However, it is preferable that the layer thickness is 50 to 500 μm.

In addition, the stimulable phosphor layer does not necessarily need to be formed by directly applying a coating solution onto the support as described above, but can be formed by separately applying it onto a sheet such as a glass plate, metal plate, or plastic sheet. After a phosphor layer is formed by applying a liquid and drying, the phosphor layer may be pressed onto a support, or the support and the phosphor layer may be bonded together using an adhesive.

Next, a protective film formed of a coating film of a fluororesin soluble in an organic solvent, which is a characteristic feature of the radiation image storage panel of the present invention, will be described.

The protective film of the radiation image storage panel of the present invention is prepared by applying a coating liquid of a protective film forming material containing a fluororesin soluble in an organic solvent.
It is formed by applying it uniformly to the surface of the phosphor layer using a doctor blade or the like and drying it. Of course, this protective film may be formed simultaneously with the formation of the phosphor layer by simultaneous multilayer coating.

Fluorine resins are polymers of olefins containing fluorine (fluoroolefins) or copolymers containing olefins containing fluorine as a copolymer component, such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride. , polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, and fluoroolefin-vinyl ether copolymer.

Fluororesins are generally insoluble in organic solvents, but copolymers containing fluoroolefins as copolymer components are
Some other structural units (other than fluoroolefins) to be copolymerized may be soluble in organic solvents, so it can be easily dissolved by dissolving the resin in an appropriate solvent and coating the solution on the phosphor layer and drying it. A protective film can be formed. An example of such a copolymer is a fluoroolefin-vinyl ether copolymer. In addition, polytetrafluoroethylene and its alterants are also soluble in suitable fluorinated organic solvents such as perfluorosolvents, so they can be coated similarly to the copolymers containing the above-mentioned fluoroolefins as copolymer components. A protective film can be formed by this method.

The protective film of the radiation image conversion panel of the present invention may contain a resin other than a fluororesin, or may contain a crosslinking agent, a hardening agent, an anti-yellowing agent, etc. as described below. good. However, in order to fully achieve the above-mentioned purpose, the content of the fluororesin in the protective film is suitably 30% by weight or more, preferably 50% by weight.
The content is preferably 70% by weight or more.

Examples of resins other than fluororesin contained in the protective film of the radiation image storage panel of the present invention include polyurethane resins, polyacrylic resins, cellulose derivatives, polymethyl methacrylate, polyester resins, and epoxy resins. can.

Furthermore, the fluororesin used in the present invention is preferably crosslinked, since this increases the strength of the resin and increases the durability as a protective film.

Therefore, the above-mentioned coating liquid for the protective film forming material may contain a resin other than the fluororesin, a crosslinking agent, etc., and may further contain an anti-yellowing agent.

In addition, for the purpose of improving the sharpness of the obtained image, at least one of the above layers constituting the radiation image conversion panel of the present invention is colored so that it absorbs excitation light and does not absorb stimulated luminescence light. It may be colored with an agent (see Japanese Patent Publication No. 54-23400).

Examples and comparative examples of the present invention are described below. However, the present invention is not limited to this example.

[Example 1] As a phosphor layer forming material, phosphor: BaFBro, 8I. , , :0.001
600 g of Eu'', 15.8 g of polyurethane resin (Desmolak 4125, manufactured by Jubilee Urethane ■), and 2.0 g of bisphenol A type epoxy resin were added to a mixed solvent of methyl ethyl ketone and toluene (1:1), and dispersed with a propeller mixer. So, the viscosity is 25
A coating solution of ~30 PS was prepared.

This coating solution was applied onto the undercoat paste using a doctor blade, and then dried at 100° C. for 15 minutes to form a phosphor layer.

Next, as protective film forming materials, fluororesin: fluoroolefin-vinyl ether copolymer (Lumiflon LP100 manufactured by Asahi Glass ■) 70 g, crosslinking agent: isocyanate (Desmodur Z4370 manufactured by Sumitomo Bayer Urethane ■) 25 g, bisphenol A type epoxy 5 g of the resin was added to a mixed solvent of toluene and isopropyl alcohol (1:1) to prepare a coating liquid with a viscosity of 2 to 3 PS. This coating liquid was applied onto the phosphor layer previously formed as described above using a doctor blade, and then heated at 120°C for 30 minutes.
Heat treated for 0 minutes to heat cure and dry to a thickness of 1
A protective film of 0 μm was provided.

The radiation image storage panel of the present invention was manufactured in the manner described above.

[Comparative Example 1] In Example 1, the protective film forming material was a polyurethane resin (Desmolac 4125 manufactured by Bayer Urethane ■).
70 g, crosslinking agent: isocyanate (Desmodur Z4370 manufactured by Sumitomo Bayer Urethane ■) 25 g, bisphenol A type epoxy resin 5 g.

A radiation image conversion panel was manufactured in the same manner as in Example 1 except for the following.

[Example 2] In Example 1, the protective film forming material was a fluorine-based tree fI.
: Fluoroolefin-vinylethyl copolymer (Lumiflon LF200 manufactured by Asahi Glass ■) 75 g, crosslinking agent: hexamethylol melamine 25 g, bisphenol A type epoxy resin 5 g, yellowing inhibitor: alkyl diallylphosphite 1 g.

A radiation image conversion panel of the present invention was manufactured in the same manner as in Example 1 except for the following.

[Comparative Example 2] In Example 2, the protective film forming material was 75 g of polyurethane resin (Lisbon 3354 manufactured by Dainippon Ink ■).
, Cross-linking agent: 25 g of isocyanate (Sumidur L manufactured by Jujube Bayer Urethane ■).

A radiation image storage panel was produced in the same manner as in Example 2, except that 5 g of bisphenol A type epoxy resin and 1 g of alkyl diallylphosphite as anti-yellowing agent were used.

-1゛reno.

The following conveying member was placed on the surface of the protective film of the four types of radiation image conversion panels manufactured as described above.

A roller made of polyurethane rubber, a belt made of nitrile rubber, a belt made of polyester, a suction cup made of nitrile rubber, and a conveying member larger than that placed thereon were left for 24 hours at a temperature of 60° C. and a humidity of 80%. Next, after wiping the surface of the protective film with isopropyl alcohol, X-ray irradiation is performed, followed by excitation with He-Ne laser light and reading.
The effect of dirt on the image was observed.

As a result of observation, no change was observed on the images in any of Examples 1.2, but in all of the radiation image conversion panels of Comparative Example 1.2, there was a sensitivity change in the contact area with the above-mentioned conveying member. A decrease was observed.

Furthermore, when observing the surface of the protective film, in all of the radiation image conversion panels of Comparative Example 1.2, discoloration was observed in the contact area with the above-mentioned conveying member, but in all of the panels of Example 1.2, No changes were observed.

= 2? Regarding the panels of Example 1.2 and Comparative Example 1.2, the sensitivity (stimulated luminescence amount) of the part that was in contact with the conveying member was calculated from the image data read in Comparative Test 1, and the sensitivity with respect to the conveying member was calculated. Changes in sensitivity before and after contact were compared.

The results are shown in Table 1. However, in Table 1, the numerical values are relative values with the sensitivity before contact as 100.

The following margins are shown in Table 1 Polyurethane Nitrile Rubber Polyester Nitrile Rubber Belt Belt Sucker Example 1 Rear Example 2 Rear 100 Comparative Example 1 Rear Comparative Example 2 As is clear from Table 1, Example 1. The radiation image conversion panel of the present invention in No. 2 shows only a sensitivity decrease of about 5% at most (as shown in Comparative Test 1, this degree of sensitivity decrease is at a level that is completely unrecognizable on images). In contrast, the panel of the comparative example shows a decrease in sensitivity of at least 17%.

[Example 3] In Example 1, 70 g of fluoroolefin-vinyl ether copolymer (Fluonate, manufactured by Dainippon Ink. Example 1 except that 30 g of Sumidur N made of urethane was used.
A radiation image conversion panel of the present invention was manufactured in the same manner as described above.

[Example 4] On the phosphor layer formed in the same manner as in Example 1, a 5% by weight solution of a fluorine-based organic solvent of a modified polytetrafluoroethylene resin (Cytotsubu manufactured by Asahi Glass ■) was applied using a doctor blade. After coating, it was dried for 10 minutes at room temperature. Further heat at 120°C to completely remove residual solvent.
This was dried for 5 minutes to form a protective film with a thickness of 10 μm, thereby producing a radiation image storage panel of the present invention.

[Example 5] Fluororesin: Modified polytetrafluoroethylene, 11 bodies (TEFLON AF-1600 manufactured by Tuhon) for 7 y
Basic organic solvent (FLυ0RINER manufactured by Sumitomo 3M)
TFC-75) to prepare a 4% by weight solution. A radiation image storage panel of the present invention was manufactured in the same manner as in Example 4, except that this solution was used as the protective film forming material coating liquid.

A comparative test similar to Comparative Test 1 was conducted on the radiation image conversion panels of Examples 3 to 5 manufactured as described above.

As a result, it was found that the radiation image conversion panels of Examples 3 to 5 had no change in the images before and after contact with the conveying member. A comparative test similar to Comparative Test 2 was conducted.

The results are shown in Table 1. However, in Table 2, the numerical values are relative values with the sensitivity before contact as 100.

Margin Table 2: Polyurethane Nitrile Rubber Polyester Nitrile Rubber Belt Belt Suction Cup Back 100 As is clear from Table 2, the radiation image conversion panels of the present invention of Examples 3 to 5 have a maximum The sensitivity decreases by only about 5%.

As is clear from the results of the above examples and comparative tests, the radiation image conversion panel of the present invention is free from stains caused by plasticizers that seep out from conveying members such as belts and rollers, and can be easily removed by wiping. It has a protective film that can be formed by coating.

Patent applicant: Fuji Photo Film Co., Ltd. Representative: Yasuo Yanagawa, patent attorney

Claims (1)

[Claims] 1. A radiation image conversion panel having a phosphor layer made of a stimulable phosphor and a protective film, characterized in that the protective film is a coating film containing a fluororesin soluble in an organic solvent. A radiographic image conversion panel.