JPH0631916B2 - Radiation image conversion panel - Google Patents

Description

Description: 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, and more specifically, to a radiation image conversion panel containing iodine. The present invention relates to a radiation image conversion panel using a fluorescent substance.

[Technical Background of the Invention and Prior Art] Recently, as a method for obtaining a radiation image as an image, Japanese Patent Laid-Open No.
A radiation image conversion method using a stimulable phosphor as described in JP-A-12145 is proposed and put to practical use. The radiation image conversion method uses a radiation image conversion panel containing a stimulable phosphor (also referred to as a stimulable phosphor sheet), and the radiation transmitted through a subject or the radiation emitted from a subject is stored in the panel. Accumulated in the stimulable phosphor by absorbing it in the stimulable phosphor, and then exciting the stimulable phosphor in time series with electromagnetic waves (excitation light) such as visible light and infrared rays. The emitted radiation energy is emitted as fluorescence (stimulated luminescence), the fluorescence is photoelectrically read to obtain an electric signal, and the obtained electric signal is imaged.

According to this method, compared with the conventional radiographic method using a combination of a radiographic film and an intensifying screen, it is possible to obtain a radiographic image having a large amount of information with a much smaller radiation dose. There is. Therefore, this method has a very high utility value particularly in direct medical radiography such as X-ray photography for the purpose of medical diagnosis.

The radiation image conversion panel used in the above radiation conversion method has, as a basic structure, a support and a stimulable phosphor layer provided on one surface thereof. The surface of the stimulable phosphor layer opposite to the support (the surface not facing the support) is generally provided with a transparent protective film. Protects against chemical alteration or physical shock.

The stimulable phosphor layer is composed of a stimulable phosphor and a binder that contains and supports the stimulable phosphor in a dispersed state. The stimulable phosphor layer absorbs radiation such as X-ray and then emits excitation light. It has the property of exhibiting stimulated emission upon irradiation. 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 the subject is displayed on the panel. It is formed as an accumulated image of radiation energy. This accumulated image can be emitted as stimulated emission light by irradiating the excitation light, and the accumulated image of radiation energy is imaged by photoelectrically reading this stimulated emission light and converting it into an electric signal. It becomes possible to do.

Although the radiation image conversion method is a very advantageous image forming method as described above, the radiation image conversion panel used in this method is also similar to the intensifying screen used in the conventional radiographic method,
It is desired to provide an image having high sensitivity and good image quality (sharpness, graininess, etc.). In particular, when the human body is used as a subject, it is desired that the sensitivity of the panel be as high as possible in order to reduce the exposure dose as much as possible.

Hitherto, as a stimulable phosphor used in a radiation image conversion panel, a divalent europium-activated barium fluorohalide phosphor (BaFX: Eu ²⁺ ; where X is I, or I and Cl and / or Br , A divalent europium-activated barium halide phosphor (BaXX ′: E)
u ²⁺ ; provided that X and X ′ are at least one halogen selected from Cl, Br and I, and X ≠
X ′, and at least one of X and X ′ contains I), a cerium-activated rare earth oxyhalide phosphor (LnOX: Ce; where Ln is at least one rare earth element selected from Y, La and lanthanide) And
X is I, or I and Cl and / or Br),
And a bismuth-activated alkali metal halide phosphor (M ^I X: Bi; where M ^I is Rb and / or Cs
And X is I, or I and Cl and / or Br) and the like containing iodine as a phosphor component is proposed.

However, when these iodine-containing stimulable phosphors are used, iodine is liberated from the phosphors to form iodine molecules (I ₂ ), so that the stimulable phosphor layer is gradually colored yellow. Tend to be. The radiation image conversion panel in which the stimulable phosphor layer is yellowed as described above has a problem that the sensitivity is significantly lowered.

In order to prevent yellowing of the panel as described above, the applicant has a group consisting of a compound having an epoxy group in the stimulable phosphor layer and / or a phosphorous acid ester, an organic tin compound and an organic acid metal salt. A patent application has already been filed for a radiation image conversion panel containing at least one compound selected from the above (Japanese Patent Application Nos. 61-25571 and 61-90618).

SUMMARY OF THE INVENTION It is an object of the present invention to provide a radiation image conversion panel in which yellowing is prevented.

Another object of the present invention is to provide a radiation image conversion panel with improved sensitivity.

Another object of the present invention is to provide a radiation image conversion panel having improved deterioration resistance over time.

In the radiation image conversion panel having the support, the stimulable phosphor layer, the adhesive layer, and the protective film in this order, the stimulable phosphor layer disperses the stimulable phosphor containing iodine. In the state of containing and supporting a binder, and in each of the stimulable phosphor layer and the adhesive layer, at least one compound selected from the group consisting of phosphite ester, organotin compound and organic acid metal salt and / or This can be achieved by the radiation image storage panel of the present invention, which is characterized by containing a compound having an epoxy group.

In the present specification, organic acid metal salt does not include organic tin.

That is, the present invention provides a phosphorous acid ester, an organotin compound and an organic compound not only in the stimulable phosphor layer of a radiation image conversion panel using a stimulable phosphor containing iodine as a phosphor component but also in the adhesive layer. By containing at least one compound selected from the group consisting of acid metal salts and / or a compound having an epoxy group, prevention of yellowing of the panel and significant improvement in sensitivity are realized.

The present inventors have found that when a stimulable phosphor containing iodine is used in a radiation image conversion panel, the stimulable phosphor layer is likely to turn yellow, and as a result, the stimulable luminescent light emitted from the phosphor is emitted. It was found that the sensitivity of the panel is remarkably lowered because the light in the blue region is absorbed in the stimulable phosphor layer. This yellowing of the stimulable phosphor layer means that iodine is liberated as I ₂ molecules from the phosphor in the coating liquid for forming the phosphor layer during the panel manufacturing process, or the phosphor formed by coating is released. The iodine liberated from the phosphor in the layer is I ₂
It was found to be due to the formation of molecules.

Further, a protective film is usually provided on the side of the stimulable phosphor layer opposite to the side in contact with the support through an adhesive layer for the purpose of physically and chemically protecting the phosphor layer. However, it has been found that not only the stimulable phosphor layer but also the adjacent adhesive layer tends to turn yellow due to liberated I ₂ molecules. In particular, when the protective layer is formed by heating and laminating it, or when the manufactured panel is left under severe conditions such as temperature and humidity, the adhesive softens and comes into contact with the iodine-containing phosphor to release free I ₂ And the adhesive layer tends to yellow. This also causes a reduction in the sensitivity of the panel, since the stimulated emission light is also absorbed by the yellowed adhesive layer.

Further, the yellowing of the stimulable phosphor layer and the adhesive layer impairs the appearance of the panel, which causes a problem of lowering the commercial value.

According to the radiation image storage panel of the present invention, the coating liquid and adhesive solution for forming the stimulable phosphor layer in the panel manufacturing process are each composed of a phosphorous ester, an organotin compound and an organic acid metal salt. By adding at least one compound selected from the above and / or a compound having an epoxy group, iodine liberated from the stimulable phosphor is trapped by these compounds, so that I ₂ molecules are formed in the coating solution. Does not occur, and I ₂ molecules are not generated due to softening of the adhesive when the protective film is formed. Further, since the formed photostimulable phosphor layer and the adhesive layer contain the compound, iodine released from the phosphor is not trapped by these compounds to form I ₂ molecule.

Furthermore, even when the environmental conditions such as temperature and humidity are severe,
It is possible to prevent the release of I ₂ molecules from the phosphor and suppress the decrease in sensitivity.

This is presumably because in the former phosphite ester, organic tin compound and organic acid metal salt, these compounds function as a kind of chelating agent for iodine and effectively capture iodine to be in a stable state. . For example, it is considered that tin in the organotin compound is bound to an iodine atom as a ligand to be in an extremely stable state. As a result, yellowing of the stimulable phosphor layer and the adhesive layer is prevented,
A highly sensitive panel can be obtained. In addition, the appearance shape of the panel does not change color over time, and its commercial value can be maintained.

When an epoxy resin is used as the compound having an epoxy group, the epoxy resin simultaneously functions as a binder and an adhesive, so that the bond between the stimulable phosphor layer and the support is strengthened and the adhesion is improved. The original function of the agent layer can be further enhanced. The case where the binder and / or the adhesive of the stimulable phosphor layer are all made of epoxy resin is also included in the present invention.

In particular, when both the compound having an epoxy group in the stimulable phosphor layer and the adhesive layer and at least one compound selected from the group consisting of phosphite ester, organic tin compound and organic acid metal salt are contained. Can be a panel with even higher sensitivity.

[Structure of the Invention] The radiation image storage panel of the present invention having the above-described preferable characteristics can be manufactured, for example, by the following method.

The support used in the present invention can be arbitrarily selected from various materials used as a support for intensifying screens in conventional radiography or various materials known as a support for radiographic image conversion panels. . Examples of such materials include cellulose acetate, polyester,
Films of plastic substances such as polyethylene terephthalate, polyamide, polyimide, triacetate and polycarbonate, metal sheets such as aluminum foil and aluminum alloy foil, ordinary paper, baryta paper, resin coated paper, pigment paper containing pigments such as titanium dioxide, Examples thereof include paper sized with polyvinyl alcohol and the like. However, in consideration of the characteristics and handling of the radiation image storage panel as an information recording material, a particularly preferable material for the support in the present invention is a plastic film. This plastic film may be kneaded with a light absorbing substance such as carbon black, or may be kneaded with a light reflecting substance such as titanium dioxide. The former is a support suitable for a radiation image conversion panel of high sharpness type, and the latter is a support suitable for a radiation image conversion panel of high sensitivity type.

On the surface of the support, a polymer substance such as gelatin is applied to form an adhesion-imparting layer (undercoat layer) for the purpose of strengthening the bond between the support and the stimulable phosphor layer, or the sensitivity or image quality is improved. For the purpose of improving the antistatic property of the panel, or for providing a light reflecting layer made of a light reflecting substance such as titanium dioxide or zirconium oxide or a light absorbing layer made of a light absorbing substance such as carbon black. An antistatic layer made of a conductive material such as carbon black, In ₂ O ₃ , SnO ₂ may be provided.

Further, as described in JP-A-58-200200, the surface of the support on the side where the phosphor layer is provided (adhesion-imparting layer, light When a reflection layer, a light absorption layer, an antistatic layer, or the like is provided, it means the surface thereof), and minute irregularities may be provided.

A stimulable phosphor layer is formed on this support.

The stimulable phosphor layer, which is a characteristic requirement of the present invention, is a stimulable phosphor containing iodine, and at least one compound selected from the group consisting of phosphorous acid esters, organotin compounds and organic acid metal salts, and And / or a layer containing a binder containing a compound having an epoxy group in a dispersed state.

The stimulable phosphor containing iodine used in the present invention,
The composition of the phosphor contains iodine. That is, it contains iodine as at least one of the matrix component, additive component and activator component of the phosphor.

This stimulable phosphor containing iodine is a phosphor that exhibits stimulable light when irradiated with excitation light after being irradiated with radiation as described above, but from a practical viewpoint, the wavelength is 400 to
300 with excitation light (for example, laser such as He-Ne laser and semiconductor laser) in the range of 900 nm
A phosphor that exhibits stimulated emission in the wavelength range of up to 500 nm is desirable.

Examples of the iodine-containing stimulable phosphor used in the radiation image storage panel of the present invention include (1) Japanese Patent Application Laid-Open No. 55-12145 (Ba1 _-X , M2 ⁺ _X ) FX. : YA (however, M ²⁺ is Mg,
At least one of Ca, Sr, Zn, and Cd, X is at least one of Cl, Br, and I, A is Eu, Tb, Ce, Tm, Dy, Pr, Ho,
At least one of Nd, Yb, and Er, and x is 0 ≦ x ≦ 0.6, y is 0 ≦ y ≦ 0.2), and the rare earth element-activated alkaline earth represented by the composition formula Metal Fluorohalide Phosphor; Further, this phosphor may contain the following additives: Li described in JP-A-56-74175.
X ′, BeX ″ ₂ , M ^III X ₃ (provided that X ′, X ″ and X are at least one of Cl, Br and I, respectively; M ^III is a trivalent metal); Be described in Japanese Patent No. 160078
O, MgO, CaO, SrO, BaO, ZnO, Al ₂
O ₃ , Y ₂ O ₃ , La ₂ O ₃ , In ₂ O ₃ , SiO ₂ , Ti
O ₂ , ZrO ₂ , GeO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅
And metal oxides such as ThO ₂ ; Z described in JP-A-56-116777.
r, Sc; B described in JP-A-57-23673, As described in JP-A-57-23675,
Si; M described in JP-A-58-206678
L (where M is at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs; L is Sc, Y, La, Ce, Pr, Nd, Pm,
Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, L
u, Al, Ga, In, and at least one trivalent metal selected from the group consisting of Tl); A baked product of a tetrafluoroboric acid compound described in JP-A-59-27980. Hexafluorosilicic acid, hexafluorotitanic acid, and hexafluorozirconic acid monovalent or divalent metal salts described in JP-A-59-47289; Na
X '(wherein X'is at least one of Cl, Br and I); V and C described in JP-A-59-56480.
Transition metals such as r, Mn, Fe, Co and Ni; M described in JP-A-59-75200
^{I X ', M' II X} "2, M III X 3, A ( however, M ^I is Li, Na, K, is at least one alkali metal selected from the group consisting of Rb, and Cs; M ^'II Is B
at least one divalent metal selected from the group consisting of e and Mg; M ^III is Al, Ga, In, and T
is at least one trivalent metal selected from the group consisting of l; A is a metal oxide; X ′, X ″ and X are at least one halogen selected from the group consisting of F, Cl, Br and I, respectively. M ^I described in JP-A-60-101173.
X '(provided that M ^I is at least one alkali metal selected from the group consisting of Rb and Cs; X'is at least one halogen selected from the group consisting of F, Cl, Br and I); M ^II 'described in Japanese Patent Laid-Open No. 61-23679
X ′ ₂ · M ^II ′ X ″ ₂ [wherein M ^II ′ is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; X ′ and X ″ are Cl and B, respectively.
at least one halogen selected from the group consisting of r and I, and X ′ ≠ X ″); and L described in Japanese Patent Application No. 60-106752.
nX ″ ₃ [where Ln is Sc, Y, La, Ce, P
r, Nd, Pm, Sm, Gd, Tb, Dy, Ho, E
at least one rare earth element selected from the group consisting of r, Tm, Yb and Lu; X ″ is F, Cl, Br
And at least one halogen selected from the group consisting of I); and (2) M ^II X ₂ · aM ^II X ′ ₂ : xEu ²⁺ (provided that M is present in JP-A-60-84381 ^{). II} is B
at least one alkaline earth metal selected from the group consisting of a, Sr and Ca; X and X ′ are Cl,
At least one halogen selected from the group consisting of Br and I, and X ≠ X '; and a is 0.1 ≦ a ≦ 10.0 and x is 0 <x ≦ 0.2) A divalent europium-activated alkaline earth metal halide phosphor represented by the following composition formula; Further, the phosphor may contain the following additives: JP-A-60-166379 Is M ^I
X ″ (where M ^I is at least one alkali metal selected from the group consisting of Rb and Cs; X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I); K described in JP-A-60-221483
X ″, MgX ₂ , M ^III X ′ ₃ (where M ^III is S
at least one trivalent metal selected from the group consisting of c, Y, La, Gd and Lu; X ″, X and X
′ Is at least one halogen selected from the group consisting of F, Cl, Br and I); B described in JP-A-60-228592; B: described in JP-A-60-228593. Is Si
O _2, P ₂ O ₅ oxide such; are described in JP 61-120882 Laid Li
X ″, NaX ″ (where X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I); Si described in JP-A-61-120883.
O: Sn described in JP-A-61-120885
X ″ ₂ (where X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I); Cs described in JP-A-61-235486.
X ″, SnX ₂ (wherein X ″ and X are at least one halogen selected from the group consisting of F, Cl, Br and I); and Cs described in JP-A-61-235487.
X ″, Ln ³⁺ (where X ″ is F, Cl, Br and I
Is at least one halogen selected from the group consisting of; Ln is Sc, Y, Ce, Pr, Nd, Sm, Gd,
It is at least one rare earth element selected from the group consisting of Tb, Dy, Ho, Er, Tm, Yb and Lu); (3) LnOX: xA described in JP-A-55-12144 (however, Ln is at least one of La, Y, Gd, and Lu; X is at least one of Cl, Br, and I; A is at least one of Ce and Tb; and x is 0. <X <0.1) A rare earth element-activated rare earth oxyhalide phosphor represented by the composition formula; (4) M ^III OX: xCe (provided that M ^{III is} disclosed in JP-A-58-69281). Is Pr, Nd, P
m, Sm, Eu, Tb, Dy, Ho, Er, Tm, Y
b, and at least one trivalent metal selected from the group consisting of Bi; X is at least one of Cl, Br, and I; x is 0 <x <0.1) cerium activated trivalent metal oxyhalide phosphors represented by the formula; (5) are described in Japanese Patent Application No. Sho 60-70484 Pat M ^I X: xBi (However, M ^I is selected from the group consisting of Rb and Cs X is at least one halogen selected from the group consisting of Cl, Br and I; and x is 0 <x <
A bismuth-activated alkali metal halide phosphor represented by a composition formula (a numerical value in the range of 0.2); (6) M ^II ₅ (PO ₄ ) ₃ X described in JP-A-60-141783. : XEu ²⁺ (However, M ^II is C
at least one alkaline earth metal selected from the group consisting of a, Sr and Ba; X is at least one halogen selected from the group consisting of F, Cl, Br and I; x is 0 <x ≦ 0 ., A divalent europium-activated alkaline earth metal halophosphate phosphor represented by the composition formula: (7) M ^II ₂ BO ₃ described in JP-A-60-157099. X: xEu ²⁺ (However, M ^II is Ca, Sr
And at least one alkaline earth metal selected from the group consisting of Ba; X is at least one halogen selected from the group consisting of Cl, Br, and I; x
Is a numerical value in the range of 0 <x ≦ 0.2), and is a divalent europium-activated alkaline earth metal haloborate phosphor represented by a composition formula; (8) Described in JP-A-60-157100. M ^II ₂ PO ₄ X: xEu ²⁺ (where M ^II is Ca, Sr
And at least one alkaline earth metal selected from the group consisting of Ba; X is at least one halogen selected from the group consisting of Cl, Br, and I; x
Is a numerical value in the range of 0 <x≤0.2), and is a divalent europium-activated alkaline earth metal halophosphate phosphor represented by a composition formula; (9) described in JP-A-60-217354. M ^II HX: xEu ²⁺ (where M ^II is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba; X is at least one selected from the group consisting of Cl, Br and I) Is halogen; x is 0
<Divalent europium-activated alkaline earth metal hydrohalide phosphor represented by a composition formula of <x ≦ 0.2); (10) JP-A-61-21183. LnX ₃ · aLn′X ′ ₃ : xCe ³⁺ (where Ln and Ln ′ are at least one rare earth element selected from the group consisting of Y, La, Gd and Ln, respectively;
X and X ′ are at least one halogen selected from the group consisting of F, Cl, Br and I, and
And X ≠ X ′; and a is 0.1 ≦ a ≦ 10.0
(X is a numerical value in the range of 0 <x ≦ 0.2), and a cerium-activated rare earth composite halide phosphor represented by the composition formula: (11) Japanese Patent Laid-Open No. 61-21182. LnX ₃ · aM ^I X ′: xCe ³⁺ (where Ln is Y,
Is at least one rare earth element selected from the group consisting of La, Gd and Lu; M ^I is Li, Na, K, C
at least one alkali metal selected from the group consisting of s and Rb; X and X ′ are respectively Cl, B
at least one halogen selected from the group consisting of r and I; and a is a numerical value in the range of 0 <a ≦ 10.0 and x is a numerical value in the range of 0 <x ≦ 0.2). cerium activated rare earth halide phosphor represented by the composition formula; (12) LnPO disclosed in JP 61-40390 discloses ₄ · _{aLnX 3:} xCe ³⁺ (although, Ln is Y, La, Gd and At least one rare earth element selected from the group consisting of Lu; X is at least one halogen selected from the group consisting of F, Cl, Br and I; and a is 0.1 ≦ a ≦ 10.0 Cerium-activated rare earth halophosphate phosphor represented by the composition formula: x is a numerical value in the range, and x is a numerical value in the range of 0 <x ≦ 0.2. (13) Described in Japanese Patent Application No. 60-78151 Has been sX · aRbX ': xEu ²⁺ (However, X and X' is at least one halogen, respectively Cl, selected from the group consisting of Br and I; and a is 0 <
a is a numerical value in the range of 10.0, and x is 0 <x ≦ 0.2
Divalent europium activated cesium halide, rubidium phosphor represented by a composition formula in the range which is of numbers); and (14) M is described in Japanese Patent Application No. Sho 60-78153 Pat ^II X ₂ · aM ^I X ′: xEu ²⁺ (where M ^II is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; M ^I is at least one selected from the group consisting of Li, Rb and Cs Alkali metal; X and X ′ are each at least one halogen selected from the group consisting of Cl, Br and I; and a is a numerical value in the range of 0.1 ≦ a ≦ 20.0 and x is x. A divalent europium-activated composite halide phosphor represented by a composition formula of 0 <x ≦ 0.2).

Among the above stimulable phosphors, divalent europium-activated alkaline earth metal fluoride halide-based phosphors containing iodine, divalent europium-activated alkaline earth metal halide-based phosphors containing iodine, iodine Rare earth element-activated rare earth oxyhalide-based phosphors containing bismuth and bismuth activated alkali metal halide-based phosphors containing iodine are particularly preferable because they exhibit high-intensity stimulated emission. However, the stimulable phosphor containing iodine used in the present invention is not limited to the above-mentioned phosphor, and contains iodine as a phosphor composition, and when irradiated with excitation light after irradiation with radiation. Any phosphor may be used as long as it exhibits stimulated emission.

A typical phosphite ester (phosphorus chelate) used in the present invention is a compound represented by the following general formula [I] or [II].

(However, A is an oxygen atom or a sulfur atom; R ¹ ,
R ² , R ³ and R ⁴ are each a hydrogen atom, an alkyl group or an aryl group, and may be the same or different from each other; X ¹ is a group consisting of a carbon atom, an oxygen atom and / or a hydrogen atom. Examples of preferable phosphite include (1) triphenylphosphite (2) Diphenyldecyl phosphite (3) Didecyl phenyl phosphite (4) Tridecyl phosphite (C ₁₀ H ₂₁ O) ₃ P (5) Trioctyl phosphite (C ₈ H ₁₇ O) ₃ P (6) Tridodecyl phosphite (C ₁₂ H ₂₅ O) ₃ P (7 ) Trioctadecyl phosphite (C ₁₈ H ₃₇ O) ₃ P (8) Trinonylphenyl phosphite (9) tridodecyl trithiophosphite (C ₁₂ H ₂₅ S) can be exemplified ₃ P.

The compounds represented by the above general formula [I] or [II] may be used alone or in combination.

The organotin compound used in the present invention is, for example, a compound represented by the following general formula [III].

(However, R ⁵ and R ⁶ are each a hydrogen atom, an alkyl group or an aryl group, and may be the same or different from each other; Y ¹ , Y ² , Y ³ and Y ⁴ are an alkyl group and an aryl group, respectively. A group, a fatty acid, a fatty acid derivative, a mercaptan or a mercapto acid, which may be the same or different from each other; X ² is an oxygen atom, a sulfur atom or maleic acid; N is 0 or an integer of 1 or more. ) Generally, an organotin compound tends to exist relatively stably in a state where a part of the organic ligand bonded to tin is replaced with halogen or the like. In the above general formula [III], Y ¹ to Y ⁴
It is believed that at least one of the ligands is replaced by iodine to stabilize it.

Examples of preferred organotin compounds include dioctyl tin mercapto, monobutyl tin trimethyl maleate,
Monobutyltin trioctyl maleate, dibutyltin dilaurate, dibutyltin laurate methyl maleate, dibutyltin dioleyl maleate, dibutyltin dimethyl maleate, dibutyls maleate, dibutyltin methoxymethyl maleate, dibutyltin dimaleate and dibutyltin. Mention may be made of mixtures with dimethyl maleate, dibutyltin dioctyl maleate, dibutyltin dioctyl thioglycolate, dibutyltin dilauryl mercaptide, tribenzyltin octyl maleate, tribenzyltin trimethylmaleate.

The organic acid metal salt used in the present invention is, for example, a compound represented by the following general formula [IV].

(R ⁷ COO) _m M [IV] (wherein R ⁷ is an alkyl group or an aryl group which may have a substituent having 1 to 20 carbon atoms; M is calcium, zinc, cadmium or barium; m Is 1
It is considered that the organic acid metal salt having the above general formula [IV] is partially substituted with iodine to form (R ⁷ COO) _{m −1} MI. However, in this specification, the metal of the organic acid metal salt does not include tin.

Examples of the organic acid in the organic acid metal salt include octylic acid, lauric acid, stearic acid, oleic acid, ricinoleic acid, naphthenic acid, 2-ethylhexylic acid, resin acid, synthetic carboxylic acid, benzoic acid, salicylic acid, and organic phosphorous acid. Can be mentioned. The organic acid may also be phenol and alkylphenol.

Examples of preferable organic acid metal salts include barium stearate, barium laurate, barium ricinoleate, barium naphthalate, barium 2-ethylhexoate,
So-called metal soaps such as calcium stearate, calcium laurate, calcium ricinoleate, zinc stearate, zinc laurate, zinc ricinoleate, and zinc 2-ethylhexoate can be mentioned.

The phosphite ester, the organotin compound and the organic acid metal salt may be used alone or in combination of two or more compounds.

Further, the compound having an epoxy group used in the present invention has at least one epoxy group in one molecule. Is to have.

The epoxy group-containing compound may be a monomer or a polymer. Examples of monomers include 1,2-epoxypropane and 1,2-epoxybutane. Examples of the polymer include bisphenol A type epoxy resin represented by the following general formula.

When the epoxy group-containing compound is a polymer, it is preferable since it can function as a binder as well as an additive for preventing yellowing. All the binders in the phosphor layer may be epoxy group-containing compounds.

At least one compound selected from the phosphite ester, the organic tin compound and the organic acid metal salt and the epoxy group-containing compound may be used alone, or may be used in combination.

Iodine liberated from the stimulable phosphor does not form I ₂ molecules because it is efficiently captured by these compounds, and therefore the stimulable phosphor layer does not turn yellow. In particular, it is preferable to use a compound such as a phosphite ester in combination with an epoxy group-containing compound because deterioration over time (decrease in sensitivity) can be prevented more effectively than when they are used alone.

Examples of the binder used in the stimulable phosphor layer in the present invention include proteins such as gelatin, polysaccharides such as dextran, or natural polymer substances such as gum arabic; and polyvinyl butyral and polyvinyl acetate. Represented by synthetic polymer substances such as nitrocellulose, ethyl cellulose, vinylidene chloride / vinyl chloride copolymer, polyalkyl (meth) acrylate, vinyl chloride / vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol, linear polyester, etc. There may be mentioned a binder. Particularly preferred among such binders are nitrocellulose, linear polyesters, polyalkyl (meth) acrylates, mixtures of nitrocellulose and linear polyesters, mixtures of nitrocellulose and polyalkyl (meth) acrylates and It is a mixture of polyurethane and polyvinyl butyral. In addition, these binders may be crosslinked.

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

First, an iodine-containing stimulable phosphor, a compound such as a phosphite ester for preventing yellowing and a binder are added to a suitable solvent, and these are sufficiently mixed to obtain a phosphor particle and a binder solution in a binder solution. A coating solution in which particles of the compound are uniformly dispersed is prepared.

Examples of the solvent for preparing the coating liquid include lower alcohols such as methanol, ethanol, 1-propanol, 2-propanol and n-butanol; chlorine atom-containing hydrocarbons such as methylene chloride and ethylene chloride; acetone, methyl ethyl ketone and methyl isobutyl. Ketones such as ketones; esters of lower fatty acids with lower alcohols such as methyl acetate, ethyl acetate, butyl acetate; ethers such as dioxane, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether; toluene; and mixtures thereof. You can

The mixing ratio of the binder and the stimulable phosphor in the coating liquid (however, when all the binder is an epoxy group-containing compound, it is equal to the ratio of the compound and the phosphor) is the desired radiation image conversion. Generally, the mixing ratio of the binder and the phosphor is selected from the range of 1: 1 to 1: 100 (weight ratio), though it depends on the characteristics of the panel, the type of the phosphor, the amount of the epoxy group-containing compound added, and the like. And it is preferable to select from the range of 1: 8 to 1:40 (weight ratio).

The addition amount of the phosphite ester, the organic tin compound and the organic acid metal salt varies depending on the type and amount of the stimulable phosphor and the type of binder, but is generally 0.0001 to 3 with respect to the phosphor. It is in the range of% by weight, preferably 0.
It is in the range of 003 to 0.3% by weight. The addition amount of the epoxy group-containing compound is generally 0.0 with respect to the phosphor.
It is in the range of 01 to 10% by weight, preferably 0.03 to
It is in the range of 3% by weight. When the amount of the epoxy group-containing compound added is less than 0.001% by weight, almost no yellowing-preventing effect is obtained, while when it is more than 10% by weight, even if all the binder is the compound, the yellowing effect is low. Although it has the effect of preventing the deterioration, it will adversely affect various characteristics such as the light emitting characteristics of the phosphor, the flexibility of the panel, and the durability.

The coating liquid contains a dispersant for improving the dispersibility of the phosphor in the coating liquid, and a binding force between the binder and the phosphor in the stimulable phosphor layer after formation. Various additives such as a plasticizer for improving may be mixed. Examples of dispersants used for such purpose include phthalic acid, stearic acid, caproic acid, lipophilic surfactants and the like. Examples of plasticizers include phosphoric acid esters such as triphenyl phosphate, tricresyl phosphate, diphenyl phosphate; phthalic acid esters such as diethyl phthalate and dimethoxyethyl phthalate; ethyl phthalyl glycolate, butyl phthalyl butyl glycolate, etc. And a polyester of polyethylene glycol and an aliphatic dibasic acid, such as a polyester of triethylene glycol and adipic acid, a polyester of diethylene glycol and succinic acid, and the like.

The coating liquid prepared as described above is then uniformly applied to the surface of the support to form a coating film of the coating liquid.
This coating operation can be performed by using an ordinary coating means such as a doctor blade, a roll coater or a knife coater.

Then, the formed coating film is gradually heated and dried to complete the formation of the stimulable phosphor layer on the support. The layer thickness of the stimulable phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the type of the stimulable phosphor, the mixing ratio of the binder and the phosphor, etc., but is usually 20 μm to 1
mm. However, this layer thickness is preferably 50 to 500 μm.

Next, a transparent protective film is provided on the surface of the stimulable phosphor layer opposite to the side in contact with the support through an adhesive layer for the purpose of physically and chemically protecting the phosphor layer. To be

The adhesive layer, which is the second characteristic requirement of the present invention, comprises at least one compound selected from the group consisting of the above phosphite ester, organotin compound and organic acid metal salt, and / or
Alternatively, it is a layer composed of an adhesive which contains and supports a compound having an epoxy group in a dispersed state.

The phosphite ester, organotin compound, organic acid metal salt and compound having an epoxy group used for preventing yellowing of the adhesive layer are selected from the compounds used for the stimulable phosphor layer. You can These compounds contained in the stimulable phosphor layer and the adhesive layer may be the same as or different from each other.

Iodine liberated from the stimulable phosphor in the stimulable phosphor layer is efficiently captured by the above compound, so that the formation of I ₂ molecules in the adhesive is prevented, and thus the yellowing of the adhesive layer is prevented. be able to. In particular, by using a compound such as a phosphite ester in combination with an epoxy group-containing compound, it is possible to more effectively prevent deterioration over time (decrease in sensitivity) as compared with the case of using the former alone or the latter alone. You can

Examples of the adhesive used in the adhesive layer in the present invention include polyacrylic resin, polyester resin, polyurethane resin, polyvinyl acetate resin and ethylene.
Examples thereof include vinyl acetate-based copolymers. The adhesive is not limited to the above resins, and for example, any resin conventionally known as an adhesive can be used.

The adhesive layer can be formed together with the protective film on the stimulable phosphor layer by the following method, for example.

First, the compound for preventing yellowing and the resin are added to an appropriate solvent and mixed sufficiently to prepare an adhesive solution. As the solvent for preparing the adhesive solution, the solvent used in forming the phosphor layer described above can be used.

The addition amount of the compound for preventing yellowing varies depending on the kind and amount of the stimulable phosphor in the phosphor layer, the kind of adhesive, etc., but the compound is a phosphite ester, an organotin compound or an organic compound. In the case of an acid metal salt, it is generally in the range of 0.003 to 30% by weight, preferably 0.01 to 1% by weight, based on the adhesive. When it is an epoxy group-containing compound, it is generally 0.03 to 1 with respect to the adhesive.
It is in the range of 00% by weight, and preferably in the range of 1 to 30% by weight.

This adhesive solution is applied uniformly on the surface of a transparent thin film for a protective film by using an ordinary coating means such as a doctor blade, a roll coater, or a knife coater to form a coating film. Is laminated on the stimulable phosphor layer with the coating film facing downward to complete the formation of the adhesive layer and the protective film on the phosphor layer.

Examples of the material of the protective film include a transparent thin film separately formed from polyethylene terephthalate, polyethylene, vinylidene chloride, polyamide and the like. The thickness of the transparent protective film is preferably about 3 to 20 μm.

The layer thickness of the adhesive layer varies depending on the type of resin, the types of materials used for the phosphor layer and the protective film, etc., but is usually in the range of 0.1 to 10 μm.

The radiation image storage panel of the present invention may have its end portion coated with a polymer substance, and the edge sticking may also contain the above-mentioned compound for preventing yellowing. In that case, the content of the phosphite ester, the organotin compound and the organic acid metal salt, and the content of the epoxy group-containing compound are each generally 0.003 to 30% by weight with respect to the polymer substance constituting the border. And 0.03 to 1
It is in the range of 00% by weight.

JP-A-55-163500, JP-A-57-963
As described in Japanese Patent Publication No. 00, etc., the radiation image storage panel of the present invention may be colored with a coloring agent,
The sharpness of the image obtained by coloring can be improved. Further, as described in JP-A-55-146447, in the radiation image storage panel of the present invention, white powder may be dispersed in the stimulable phosphor layer for the same purpose.

Next, examples and comparative examples of the present invention will be described. However,
Each of these examples does not limit the invention.

[Example 1] Polyacrylic resin (Dianal BR107, manufactured by Mitsubishi Rayon Co., Ltd.), aliphatic isocyanate (crosslinking agent: Desmodur Z4370, manufactured by Sumitomo Bayer Urethane Co., Ltd.), nitrocellulose (RS120, Daicel Chemical Industries) (stock)
Manufactured by K.K.), silicon dioxide (particle diameter: 2 to 3 μm) and bisphenol A type epoxy resin (average molecular weight: 800) are added to methyl ethyl ketone with the following composition to give a viscosity of 2.5.
A coating solution for forming an undercoat layer of ~ 6 PS (25 ° C) was prepared.

Composition of coating liquid for undercoat layer Polyacryl resin 100 g Aliphatic isocyanate 3 g Nitrocellulose 3 g Silicon dioxide 20 g Epoxy resin 10 g Carbon kneaded polyethylene terephthalate film (support, thickness) in which this coating liquid was placed horizontally on a glass plate : 250 μm) and was evenly coated with a doctor blade. After coating, the support on which the coating film was formed was placed in a dryer to dry the coating film, and an undercoat layer having a layer thickness of about 30 μm was formed on the support.

Next, a divalent europium-activated barium phosphor stimulable: the particles and the binding agent (BaFBr _0.85 I _0.15 0.001Eu ²⁺⁾ using a propeller mixer after addition of methyl ethyl ketone by the following composition And stir thoroughly to mix,
The phosphor particles are uniformly dispersed, the mixing ratio of the binder and the phosphor is 1:30 (weight ratio), and the viscosity is 25 to 35 PS (25
A coating solution for forming a phosphor layer (.degree. C.) was prepared.

Composition of coating liquid for phosphor layer Photostimulable phosphor layer 120.0 g Polyacrylic resin 3.2 g Nitrocellulose 0.4 g Epoxy resin 0.4 g This coating liquid was applied to the undercoat layer surface of the support on which the lower layer was formed. Was evenly coated with a doctor blade. Then, after coating, the support on which the coating film is formed has a temperature of 90 ° C. and a wind speed of 1.
It was heat-dried for 10 minutes under the condition of 0 m / sec. Thus, a stimulable phosphor layer having a layer thickness of about 150 μm was formed on the support.

Next, polyester resin (adhesive; Byron ^# 30
0, Toyobo Co., Ltd.), epoxy resin and methyl ethyl ketone were mixed in the following composition to prepare a 2 wt% adhesive solution.

Composition of adhesive solution Polyester-based resin 1.9 g Epoxy resin 0.1 g Methyl ethyl ketone 98 g This coating solution is uniformly applied onto a transparent film of polyethylene terephthalate (protective film, thickness: 10 μm) using a doctor blade and applied. A film was formed. Then, the transparent film was placed with the coating side facing down and laminated on the stimulable phosphor layer to form an adhesive layer and a transparent protective film having a layer thickness of 1.5 μm.

In this way, a radiation image conversion panel composed of the support, the undercoat layer, the stimulable phosphor layer, the adhesive layer and the transparent protective film was produced.

[Comparative Example 1] The same procedure as in Example 1 was carried out except that 2.0 g of the polyester resin was used in Example 1 without adding the epoxy resin to the adhesive solution. A radiation image conversion panel composed of a fluorescent layer, an adhesive layer and a transparent protective film was manufactured.

Each of the obtained radiation image conversion panels was evaluated by the following sensitivity test and forced deterioration test.

(1) Sensitivity test After irradiating the radiation image conversion panel with X-rays having a tube voltage of 89 KVp, He-Ne laser light (wavelength: 632.8 nm)
It was excited with and the sensitivity was measured.

(2) Forced deterioration test Radiation image conversion panel temperature 60 ℃, relative humidity 80% RH
After leaving it for 1 week under the condition of 1, the sensitivity was measured in the same manner as above.

The above results are summarized in Table 1.

As is clear from Table 1, the radiation image conversion panel of the present invention (Example 1) containing an epoxy group-containing compound in the stimulable phosphor layer and the adhesive layer was prepared by the stimulable phosphor layer and the adhesive during production. There was no yellowing of the agent layer, and the radiation image conversion panel in which the epoxy group-containing compound was not included in the adhesive layer (Comparative Example 1) had higher sensitivity during production and was superior in aging resistance.

Claims (10)

[Claims] 1. A radiation image conversion panel having a support, a stimulable phosphor layer, an adhesive layer and a protective film in this order,
The stimulable phosphor layer is composed of a binder that supports the stimulable phosphor containing iodine in a dispersed state, and the stimulable phosphor layer and the adhesive layer each contain a phosphite ester and an organic tin. A radiation image conversion panel comprising at least one compound selected from the group consisting of a compound and an organic acid metal salt and / or a compound having an epoxy group. 2. The adhesive layer contains at least one compound selected from the group consisting of phosphite esters, organotin compounds and organic acid metal salts in an amount of 0.003 to 3 relative to the adhesive.
The radiation image storage panel according to claim 1, wherein the radiation image storage panel is contained in an amount of 0% by weight. 3. The stimulable phosphor layer comprises a phosphite ester,
At least one compound selected from the group consisting of an organic tin compound and an organic acid metal salt is contained in the range of 0.0001 to 3% by weight with respect to the stimulable phosphor. The radiation image conversion panel according to item 1. 4. The phosphite is represented by the following general formula [I]:
A compound represented by the following formula and a compound represented by the following general formula [II]: Claim 1
The radiation image conversion panel according to the item. (However, A is an oxygen atom or a sulfur atom; R ¹ ,
R ² , R ³ and R ⁴ are each a hydrogen atom, an alkyl group or an aryl group, and may be the same or different from each other; X ¹ is a group consisting of a carbon atom, an oxygen atom and / or a hydrogen atom. is there) 5. The organotin compound is represented by the following general formula [II
The radiation image conversion panel according to claim 1, which is a compound represented by the formula [I]. (However, R ⁵ and R ⁶ are each a hydrogen atom, an alkyl group or an aryl group, and may be the same or different from each other; Y ¹ , Y ² , Y ³ and Y ⁴ are an alkyl group and an aryl group, respectively. A group, a fatty acid, a fatty acid derivative, a mercaptan or a mercapto acid, which may be the same or different from each other; X ² is an oxygen atom, a sulfur atom or maleic acid; n is 0 or an integer of 1 or more. ) 6. The radiation image conversion panel according to claim 1, wherein the organic acid metal salt is a compound represented by the following general formula [IV]. (R ⁷ COO) _m M [IV] (wherein R ⁷ is an alkyl group or an aryl group which may have a substituent having 1 to 20 carbon atoms; M is calcium, zinc, cadmium or barium; m Is 1
Is an integer greater than or equal to) 7. The adhesive layer according to claim 1, wherein a compound having an epoxy group is contained in an amount of 0.03 to 100% by weight with respect to the adhesive. Radiation image conversion panel. 8. The stimulable phosphor layer contains a compound having an epoxy group in an amount of 0.001 to 10% by weight based on the stimulable phosphor. A radiation image conversion panel according to claim 1. 9. The compound having an epoxy group is 1, 2
The radiation image storage panel according to claim 1, wherein the radiation image storage panel is at least one compound selected from the group consisting of epoxypropane, 1,2-epoxybutane, and epoxy resin. 10. A divalent europium-activated alkaline earth metal fluoride halide phosphor containing iodine as the stimulable phosphor layer, and a divalent europium-activated alkaline earth metal halide fluorescent as containing iodine. Body, containing a rare earth element-activated rare earth oxyhalide-based phosphor containing iodine, and at least one stimulable phosphor selected from the group consisting of bismuth-activated alkali metal halide-based phosphor containing iodine. The radiation image conversion panel according to claim 1, which is characterized in that.