JPH0631909B2 - 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 utilizing a stimulable phosphor. More specifically, the present invention relates to a radiation image conversion panel using a stimulable phosphor containing iodine.

[Technical Background of the Invention and Prior Art] As a method for obtaining a radiographic image as an image, a so-called radiographic method using a combination of a radiographic film having an emulsion layer made of a silver salt light-sensitive material and an intensifying screen has hitherto been used. It's being used. Recently, as an alternative method to the above radiographic method, a radiation image conversion method using a stimulable phosphor, such as that described in JP-A-55-12145, has been receiving attention. This radiation image conversion method utilizes a radiation image conversion panel (stimulable phosphor sheet) having a stimulable phosphor, and irradiates radiation transmitted through a subject or emitted from the subject to the panel. Radiation accumulated in the stimulable phosphor by absorbing the stimulable phosphor in a time series and then exciting the stimulable phosphor with electromagnetic waves (excitation light) such as visible light and infrared rays. 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 radiation image conversion method, there is an advantage that a radiation image having a large amount of information can be obtained with a much smaller radiation dose as compared with the conventional radiographic method. Therefore, this radiographic image conversion method is extremely useful in direct medical radiography such as X-ray radiography for the purpose of medical diagnosis.

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

The phosphor layer is composed of a stimulable phosphor and a binder which contains and supports the stimulable phosphor in a dispersed state. The stimulable phosphor absorbs radiation such as X-rays and then emits visible light and It has a property of emitting light (stimulated luminescence) when irradiated with electromagnetic waves (excitation light) such as infrared rays. Therefore,
Radiation transmitted through or emitted from the subject is absorbed by the phosphor layer of the radiation image conversion panel in proportion to the amount of radiation, and the radiation image of the subject or subject is on the radiation image conversion panel. Is formed as an accumulated image of. This accumulated image can be emitted as stimulated emission by being excited in time series by the electromagnetic wave, and the accumulated image of radiation energy can be imaged by photoelectrically reading this stimulated emission and converting it into an electric signal. Can be converted.

The radiographic image conversion method is a very advantageous image forming method as described above, but the radiographic image conversion panel used in this method has high sensitivity like the intensifying screen used in the conventional radiographic method. It is desired to provide an image having excellent 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 lanthanides) And
X is I, or I and Cl and / or Br),
And 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 iodine is proposed as a phosphor component.

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

The present applicant has already filed a patent application for a radiation image conversion panel obtained by adding a compound having an epoxy group to the phosphor layer in order to prevent yellowing of the panel as described above (Japanese Patent Application No. 61-61). -25571).

SUMMARY OF THE INVENTION An object of the present invention is to provide a radiation image conversion panel with improved sensitivity.

The above-mentioned object is a radiation image conversion panel having a support and a phosphor layer made of a binder which contains and supports the stimulable phosphor provided in a dispersed state on the support, wherein the stimulable phosphor is A radiation image conversion panel, which is a phosphor containing iodine, wherein the phosphor layer contains at least one compound selected from the group consisting of phosphite esters, organic tin compounds and organic acid metal salts. can do.

Further, the above-mentioned object is a support, and in the radiation image conversion panel having a phosphor layer comprising a binder provided in a dispersed state and supporting a stimulable phosphor provided thereon, the stimulable phosphor is A phosphor containing iodine, wherein the phosphor layer contains a compound having an epoxy group, and at least one compound selected from the group consisting of phosphorous acid esters, organic tin compounds and organic acid metal salts. Can be achieved by the radiation image conversion panel.

The organic acid metal salt does not include tin organic acid.

That is, the present invention is a phosphor layer of a radiation image conversion panel using a stimulable phosphor containing iodine as a phosphor component, at least one selected from the group consisting of phosphite ester, organotin compound and organic acid metal salt. By incorporating the compound (1) or a mixture of the compound and a compound having an epoxy group, a marked improvement in the sensitivity of the panel is realized.

The present inventors have found that when a stimulable phosphor containing iodine is used in a radiation image conversion panel, the phosphor layer is easily discolored into yellow, and as a result, stimulated emission light emitted from the phosphor, particularly It has been found that the sensitivity of the panel is significantly reduced because the light in the blue region is absorbed in the phosphor layer. The yellowing of the phosphor layer is caused by iodine from the phosphor in the coating liquid for forming the phosphor layer during the panel manufacturing process.
Or liberated becomes ₂ molecule, or iodine liberated from phosphor coating formed phosphor layer has been found that due to the formation of the I ₂ molecule.

According to the radiation image conversion panel of the present invention, at least one compound selected from the group consisting of phosphite, an organic tin compound and an organic acid metal salt in the coating liquid for forming the phosphor layer in the panel manufacturing process, or By adding a compound having an epoxy group together with these compounds, iodine liberated from the stimulable phosphor does not form an I ₂ molecule because it is trapped by these compounds. Further, since the phosphor layer formed by coating contains the above compound, iodine released from the phosphor is not trapped by these compounds to form I ₂ molecule. It is speculated that this is because the compound functions as a chelating agent for iodine, effectively traps iodine, and becomes stable. For example, in an organic tin compound, it is considered that tin in the compound is bound to an iodine atom as a ligand and becomes extremely stable. As a result, yellowing of the phosphor layer is prevented and a highly sensitive panel can be obtained.

Further, the panel in which the phosphor layer contains a compound having an epoxy group and at least one compound selected from the group consisting of phosphite ester, organic tin compound and organic acid metal salt has higher sensitivity.

Further, when an epoxy resin is used as a compound having an epoxy group, the epoxy resin simultaneously has a function as a binder, and therefore, in addition to the improvement in sensitivity as described above, the adhesive force between the support and the phosphor layer is increased. Can be increased. It should be noted that a case where all the binders are epoxy resins without using other binders is also included in the present invention.

[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.

The surface of the support is coated with a high molecular substance such as gelatin to form an adhesion-imparting layer for the purpose of strengthening the bond between the support and the phosphor layer, or titanium dioxide, oxidized for the purpose of improving sensitivity or image quality. For the purpose of providing a light reflecting layer made of a light reflecting substance such as zirconium or a light absorbing layer made of a light absorbing substance such as carbon black, or for improving the antistatic performance of the panel, carbon black, In ₂
O _3, an antistatic layer comprising a conductive material such as SnO ₂ may be provided.

Further, as described in JP-A-58-200200, for the purpose of improving the sharpness of the image, the surface of the support on the phosphor layer side (the surface of the support on the phosphor layer side is provided with adhesiveness). When a layer, a light reflection layer, a light absorption layer or an antistatic layer is provided, it means the surface thereof), and minute irregularities may be provided.

Next, a phosphor layer is formed on the support. The phosphor layer, which is a characteristic requirement of the present invention, disperses a stimulable phosphor containing iodine and at least one compound selected from the group consisting of phosphorous acid esters, organic tin compounds and organic acid metal salts. A layer consisting of a binder to support contained in the state, or a stimulable phosphor containing iodine, and at least one compound selected from the group consisting of phosphites, organotin compounds and organic acid metal salts, and an epoxy group It is a layer comprising a compound having the compound and a binder containing and supporting the mixture of the compound 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 stimulated emission upon irradiation with excitation light after irradiation with radiation as described above, but from a practical standpoint, the wavelength is 400-
300 with excitation light (for example, laser such as He-Ne laser and semiconductor laser) in the range of 900 nm
It is desirable to use a phosphor that exhibits stimulated emission in the wavelength range of up to 500 nm.

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, the phosphor may contain the following additives: L described in Japanese Patent Application No. 54-150873.
iX ′, BeX ″ ₂ , M ^III X ″ ″ ₃ (where X ′,
X ″ and X ″ ″ are each at least one of Cl, Br and I; M ^III is a trivalent metal); Be described in Japanese Patent Application No. 55-160078.
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, Rb, and is at least one alkali metal selected from the group consisting of Cs; M ^'II is at least one trivalent metal selected from the group consisting of Be and Mg; M ^III is At least one trivalent metal selected from the group consisting of Al, Ga, In, and Tl; A is a metal oxide; X ', X "and X"' are F, Cl, Br and I, respectively. Which is at least one halogen selected from the group consisting of: 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 described in Japanese Patent Application No. 59-145385
^II ′ X ′ ₂ · M ^II ′ X ″ ₂ [where M ^II ′ is Ba, Sr
And at least one alkaline earth metal selected from the group consisting of Ca; X ′ and X ″ are each C
at least one halogen selected from the group consisting of 1, Br 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) The divalent europium-activated alkaline earth metal halide phosphor represented by the following composition ratio: The phosphor may contain the following additives: Japanese Patent Application No. 60-166379. 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 Japanese Patent Application No. 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 ″ ″ are all selected from the group consisting of F, Cl, Br and I At least one halogen); B described in Japanese Patent Application No. 59-84356; Si described in Japanese Patent Application No. 59-84358.
Oxides such as O ₂ and P ₂ O ₅ ; L described in Japanese Patent Application No. 59-240451
iX ″, NaX ″ (where X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I); S described in Japanese Patent Application No. 59-240452.
iO: S described in Japanese Patent Application No. 59-240454
nX " ₂ (where X" is at least one halogen selected from the group consisting of F, Cl, Br and I); Cs described in Japanese Patent Application No. 60-78033.
X ″, SnX ″ ″ ₂ (wherein X ″ and X ″ ″ are at least one halogen selected from the group consisting of F, Cl, Br and I); and Japanese Patent Application No. 60-78035. Cs listed
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 JP 60-70484 specification 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 of (0.2); (6) M ^II ₅ (PO ₄ ) ₃ described in Japanese Patent Application No. 58-247237. X: 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 And a divalent europium-activated alkaline earth metal halophosphate phosphor represented by a composition formula
((7) M ^II ₂ BO ₃ X: xEu ₂₊ described in Japanese Patent Application No. 59-13153 (M ^II is Ca, S
at least one alkaline earth metal selected from the group consisting of r and 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 a divalent europium-activated alkaline earth metal haloborate phosphor represented by a composition formula; (8) described in Japanese Patent Application No. 59-13154. 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 the divalent europium-activated alkaline earth metal halophosphate phosphor is represented by the composition formula; (9) described in Japanese Patent Application No. 59-74364. M ^II HX: xEu ₂₊ (wherein M ^II is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba; X is at least selected from the group consisting of Cl, Br and I) Is a kind of halogen; x is 0
<Divalent europium-activated alkaline earth metal hydrohalide phosphor represented by the composition formula of <x ≦ 0.2) (10) Described in Japanese Patent Application No. 59-142010. LnX ₃ · aLn′X ′ ₃ : xCe ₃₊ (where L
n and Ln ′ are at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; X and X ′ are at least one halogen selected from the group consisting of F, Cl, Br and I, respectively. And X ≠ X ′; and a is 0.1 <a ≦ 1
A numerical value in the range of 0.0, and 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 Application No. 59-141489. LnX ₃ · aM ^I X ′: xCe ₃₊ (where Ln is at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; M ^I is Li; Na,
At least one alkali metal selected from the group consisting of K, Cs and Rb; X and X ′ are each C
is at least one halogen selected from the group consisting of 1, Br, 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. (12) LnPO ₄ .aLnX ₃ : xCe ₃₊ (provided that LnPO ₄ .aLnX ₃ : xCe ₃₊ is disclosed in Japanese Patent Application No. 59-163361.
Is at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; X is F, Cl, Br
And at least one halogen selected from the group consisting of I and I; and a is a numerical value in the range of 0.1 ≦ a ≦ 10.0 and x is a numerical value in the range of 0 <x ≦ 0.2)
(13) CsX · aRbX ′: xEu ₂₊ described in Japanese Patent Application No. 60-78151 (wherein X and X ′ are Cl respectively). , Br and I is at least one halogen selected from the group consisting of; 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₊ (However, M ^II is B
at least one alkaline earth metal selected from the group consisting of a, Sr and Ca; M ^I is at least one alkali metal selected from the group consisting of Li, Rb and Cs; X and X ′ are each Cl , At least one halogen selected from the group consisting of Br and I; and a is a numerical value in the range of 0.1 ≦ a ≦ 20.0 and x is a numerical value in the range of 0 <x ≦ 0.2. There is a divalent europium-activated composite halide phosphor represented by the composition formula (1);

Among the above stimulable phosphors, a divalent europium-activated alkaline earth metal fluoride halide phosphor containing iodine, a divalent europium-activated alkaline earth metal halide phosphor containing iodine, iodine The rare earth element-activated rare-earth oxyhalide-based phosphor containing and the bismuth-activated alkali metal halide-based phosphor containing iodine exhibit particularly high photostimulable luminescence, and thus are particularly preferable.
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.

In the present invention, the compound contained in the phosphor layer in order to prevent yellowing of the phosphor layer is at least one compound selected from the group consisting of phosphorous acid esters, organic tin compounds and organic acid metal salts. These compounds have a function of effectively trapping iodine liberated from the fluorescent substance and inhibiting the formation of I ₂ molecules. That is, it functions as a chelating agent.

A typical phosphite ester (phosphorus chelate) used in the present invention is a compound represented by the following general formula [I] or general formula [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 these may be the same or different from each other; X ¹ is composed of a carbon atom, an oxygen atom and a hydrogen atom. Examples of preferable phosphite ester are (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 compound represented by the above general formula [I] or [II] is
Each 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 these may be the same or different from each other; Y ¹ , Y ² , Y ³ and Y ⁴ are respectively An alkyl group, an aryl group, a fatty acid, a fatty acid derivative, a mercaptan or a mercapto acid, and these may be the same or different from each other; X ² is an oxygen atom, a sulfur atom or maleic acid; and n is (Organic tin compound is an integer of 0 or 1 or more) Generally, a part of the organic ligand bonded to tin is substituted with halogen or the like, and thus it is likely to exist relatively stably. In the above general formula [III], it is considered that at least one ligand of Y ¹ to Y ⁴ is substituted with iodine to be stabilized.

Examples of preferred organotin compounds include dioctyltin mercapto, monobutyltin-trimethylmaleate,
Monobutyltin-trioctyl maleate, dibutyltin-dilaurate, dibutyltin-laurate-methyl maleate, dibutyltin-dioleyl maleate, dibutyltin-dimethylmaleate, dibutyltin-maleate, dibutyltin-methoxymethylmaleate, dibutyltin-dimaleate and dibutyltin- Mention may be made of mixtures with dimethyl maleate, dibutyltin-dioctyl maleate, dibutyltin-dioctylthioglycolate, dibutyltin-dilauryl mercaptide, tribenzyltin-octylmaleate, tribenzyltin-trimethylmaleate.

The organic acid metal salt used in the present invention is represented by, for example, 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 a positive integer) In the organic acid metal salt having the above general formula [IV], it is considered that a part of the organic acid is replaced with iodine to form (R ⁷ COO) _m-1 MI. However, the organic acid metal salt used in the present invention does not include organic tin.

Examples of the organic acid metal salt used in the present invention 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. It is a metal salt of an organic acid such as. The organic acid of this organic acid metal salt may be phenol or alkylphenol.

Examples of such organic acid metal salts include barium stearate, barium laurate, barium ricinoleate,
Barium naphthenate, barium 2-ethylhexoate, calcium stearate, calcium laurate,
Examples include so-called metal soaps such as calcium ricinoleate, zinc stearate, zinc laurate, zinc ricinoleate, and zinc 2-ethylhexoate.

As described above, the phosphorous acid ester, the organic tin compound and the organic acid metal salt may be contained in the phosphor layer singly, or may be contained in the phosphor layer by appropriately combining two or more kinds. . That is, it is sufficient that at least one of these compounds is contained in the phosphor layer, and as a result, yellowing of the phosphor layer is prevented.

The addition amount of the compound is the type and amount of the stimulable phosphor,
Although it varies depending on the kind of the binder and the like, it is generally in the range of 0.0001 to 3% by weight, preferably 0.003 to 0.3% by weight, based on the phosphor.

Furthermore, in combination with the above compound, a compound having an epoxy group may be contained in the phosphor layer. However,
The compound having an epoxy group is not only used as an additive,
It may be used as the binder itself.

A compound having an epoxy group is a compound having 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. Note that all the binders may be epoxy group-containing compounds.

Iodine the phosphite liberated from the stimulable phosphor, not only at least one compound of the organotin compound and an organic acid metal salt, in order to be efficiently captured by the epoxy group-containing compound, I ₂ It does not form molecules and therefore the phosphor layer does not turn yellow. By using both of these compounds in combination, deterioration over time (decrease in sensitivity) can be prevented more effectively than in the case of using the former alone or the latter alone.

The amount of the epoxy group-containing compound added varies depending on the type and amount of the stimulable phosphor, the amount of the compound such as the phosphite ester, the type of binder, etc. It is in the range of 10% by weight, preferably in the range of 0.03 to 3% by weight. When the addition amount of the epoxy group-containing compound is less than 0.001% by weight, the synergistic yellowing preventing effect due to this is hardly obtained.
On the other hand, when the amount is more than 10% by weight, even if all the binders are the compounds, there is an effect of preventing yellowing, but the luminescent properties of the phosphor, flexibility of the panel, durability, etc. It will have an adverse effect.

In the present invention, examples of the binder used in the phosphor layer 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. Note that these binders may be crosslinked with a crosslinking agent.

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

First, a stimulable phosphor and a binder, at least one compound selected from the group consisting of the above phosphite ester, an organotin compound and an organic acid metal salt, and in some cases, a compound having an epoxy group is added to a suitable solvent. Then, these are thoroughly mixed to prepare a coating solution in which the phosphor particles and the above compound are uniformly dispersed in the binder solution.

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; lower fatty acids such as methyl acetate, ethyl acetate, butyl acetate, lower alcohols and esters; dioxane,
Ethers such as ethylene glycol monoethyl ether and ethylene glycol monomethyl ether; toluene;
And a mixture thereof can be mentioned.

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 is equal to the ratio of the compound and the phosphor), the target radiation image conversion panel. Generally, the mixing ratio of the binder and the phosphor is from 1: 1 to 1, though it varies depending on the characteristics of, the type of the phosphor, the amount of the epoxy group-containing compound added (when the epoxy group-containing compound is used as an additive), 1: 100 (weight ratio)
It is preferable to select from the range of, and especially from the range of 1: 8 to 1:40 (weight ratio).

The coating liquid contains a dispersant for improving the dispersibility of the phosphor in the coating liquid, and also for improving the binding force between the binder and the phosphor in the formed phosphor layer. Various additives such as plasticizers may be mixed. Examples of dispersants used for such purpose include:
Examples thereof include phthalic acid, stearic acid, caproic acid and lipophilic surfactants. 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 phosphor layer on the support. The layer thickness of the phosphor layer is the characteristics of the intended radiation image conversion panel,
The thickness is usually 20 μm to 1 mm, although it varies depending on the type of phosphor, the mixing ratio of the binder and the phosphor, and the like. However, this layer thickness is preferably 50 to 500 μm.

The phosphor layer does not necessarily have to be formed by directly applying the coating liquid on the support as described above.For example, the coating liquid may be separately applied on a sheet such as a glass plate, a metal plate, or a plastic sheet. After the phosphor layer is formed by drying, the phosphor layer may be bonded to the support by pressing it on the support or by using an adhesive.

A transparent protective film may be provided on the surface of the phosphor layer opposite to the side in contact with the support for the purpose of physically and chemically protecting the phosphor layer.

The transparent protective film may be, for example, a cellulose derivative such as cellulose acetate or nitrocellulose; or a transparent polymer material such as polymethylmethacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, or vinyl chloride / vinyl acetate copolymer. It can be formed by a method in which a solution prepared by dissolving a high-molecular substance in a suitable solvent is applied to the surface of the phosphor layer. Alternatively, it can also be formed by a method of adhering a transparent thin film separately formed from polyethylene terephthalate, polyethylene, polyvinylidene chloride, polyamide or the like to the surface of the phosphor layer with an appropriate adhesive. The thickness of the transparent protective film thus formed is
It is preferably about 0.1 to 20 μm.

In addition, the radiation image storage panel of the present invention may be provided with an edge sticker which is covered with a polymer film at the end thereof. Then, when the edge sticking is provided, it is preferable that the coating liquid also contains the compound according to the present invention for preventing yellowing as described above.

Further, JP-A-55-163500 and JP-A-57-
As described in Japanese Patent Publication No. 96300, the radiation image conversion panel of the present invention may be colored with a coloring agent, and the sharpness of an 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 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 present invention.

[Example 1] bivalent europium-activated barium phosphor of the stimulable: particles ^{_{(BaFBr 0.85 I 0.15 0.001Eu 2+)}} 12
0 g, 24 g of a methyl ethyl ketone solution of acrylic resin (solid content: 10% by weight), 6 g of a methyl ethyl ketone solution of nitrocellulose (solid content: 10% by weight), and a methyl ethyl ketone solution of diphenyldecyl phosphite (molecular weight: 374) (solid content: 50 Wt%) 0.04 g
Was added to 18 g of methyl ethyl ketone, and then sufficiently stirred and mixed by using a propeller mixer to uniformly disperse the phosphor particles, the mixing ratio of the binder and the phosphor was 1:40 (weight ratio), and the viscosity was 25-. A coating solution of 30PS (25 ° C) was prepared.

Carbon black kneaded polyethylene terephthalate film placed horizontally on a glass plate (support, thickness: 2
50 μm) was coated with this coating solution using a doctor blade while changing the diameter of the opening of the doctor blade. Then, the support having the coating film formed on the coating solution is placed in a dryer, and the temperature inside the dryer is set from 25 ° C to 100 ° C.
The coating film was dried by gradually raising the temperature to ℃. In this way, the phosphor layer was formed on the support with the layer thickness varied in the range of about 200 to 500 μm.

Next, a polyethylene terephthalate film (thickness: 12 μm, with a polyester-based adhesive applied) is placed on the phosphor layer with the adhesive layer side facing down to adhere the transparent protective film. Formed.

Thus, a radiation image conversion panel composed of the support, the phosphor layer and the transparent protective film was produced.

[Comparative Example 1] A support, a phosphor layer and a support were prepared in the same manner as in Example 1 except that 20 g of methyl ethyl ketone was used without adding a diphenyldecyl phosphite solution to the coating solution. A radiation image conversion panel composed of a transparent protective film was manufactured.

X of the tube voltage of 80 KVp was applied to each obtained radiation image conversion panel.
He-Ne laser light (wavelength: 63
The sensitivity was measured by exciting at 2.8 nm). The results are shown in FIG.

FIG. 1 is a graph in which the horizontal axis represents the layer thickness of the phosphor layer and the vertical axis represents the relative sensitivity. In FIG. 1, Curve 1: Radiation image conversion panel containing phosphite (Example 1) Curve 2: Radiation image conversion panel not containing phosphite (Comparative Example 1).

As is clear from FIG. 1, the radiation image storage panel of the present invention containing phosphorous acid ester in the phosphor layer (Example 1) was compared with the radiation image storage panel containing no phosphorous ester (Comparative Example 1). The sensitivity was remarkably improved. Further, in the panel of Comparative Example 1, the yellowing of the phosphor layer was remarkable, and the sensitivity did not change much even if the thickness of the phosphor layer was increased, but the panel of the present invention did not yellow the phosphor layer at all, The sensitivity increased in proportion to the layer thickness.

[Example 2] Example 2 except that 120 g of bismuth-activated cesium iodide phosphor (CsI: 0.001 Bi) was used as the stimulable phosphor and 0.04 g of dioctyltin mercapto was used as the organotin compound in Example 1. By performing the same treatment as the method of 1, the layer thickness on the support is 250 μm.
The phosphor layer of was formed.

Then, the same treatment as in the method of Example 1 was performed to produce a radiation image conversion panel composed of the support, the phosphor layer and the transparent protective film.

Comparative Example 2 The procedure of Example 2 was repeated except that dioctyltin mercapto was not added to the coating solution, to thereby form a support, a phosphor layer and a transparent protective film. A radiation image conversion panel was manufactured.

The sensitivity of each radiation image conversion panel obtained in Example 2 and Comparative Example 2 was measured in the same manner as above. The results are shown in Table 1. In addition, the sensitivity was represented by setting the sensitivity of the panel of Example 2 to 100.

Example 3 In Example 1, a divalent europium-activated barium chlorobromide-based phosphor (BaClBr _0.9 I) was used as the stimulable phosphor.
_0.1 : 0.001Eu ²⁺ ) 120 g, and the same treatment as in Example 1 except that 0.02 g of barium stearate and 0.02 g of zinc stearate are used as the organic acid metal salt to give a support. Layer thickness of about 25
A 0 μm phosphor layer was formed.

Then, the same treatment as in the method of Example 1 was performed to produce a radiation image conversion panel composed of the support, the phosphor layer and the transparent protective film.

[Comparative Example 3] A support, a phosphor layer and a transparent protective film were prepared in the same manner as in Example 3, except that barium stearate and zinc stearate were not added to the coating solution. A radiation image conversion panel composed of

Each of the radiation image conversion panels obtained in Example 3 and Comparative Example 3 was irradiated with X-rays having a tube voltage of 80 KVp, and then excited with semiconductor laser light (wavelength: 780 nm) to measure the sensitivity. The results are shown in Table 2. In addition, the sensitivity was represented by setting the sensitivity of the panel of Example 3 to 100.

[Example 4] divalent europium-activated barium phosphor of the stimulable: particles ^{_{(BaFBr 0.85 I 0.15 0.001Eu 2+)}} 12
0 g, acrylic resin methyl ethyl ketone solution (solid content: 10% by weight) 24 g, nitrocellulose methyl ethyl ketone solution (solid content: 10% by weight) 6 g, diphenyldecyl phosphite (molecular weight: 374) methyl ethyl ketone solution (solid content: 50% by weight) %) 0.04 g, and bisphenol A type epoxy resin (average molecular weight: 90
0) Methyl ethyl ketone solution (solid content: 50% by weight)
After 2 g was added to 18 g of methyl ethyl ketone, the mixture was sufficiently stirred and mixed using a propeller mixer to uniformly disperse the phosphor particles, and the binder and the phosphor had a mixing ratio of 1:40 (weight ratio) and a viscosity of 25. A coating solution of -30 PS (25 ° C) was prepared.

Carbon black kneaded polyethylene terephthalate film placed horizontally on a glass plate (support, thickness: 2
This coating solution was applied onto 50 μm) using a doctor blade. After the coating, the support on which the coating film was formed was placed in a dryer, and the temperature inside the dryer was gradually raised from 25 ° C. to 100 ° C. to dry the coating film.
Thus, a phosphor layer having a layer thickness of about 400 μm was formed on the support.

Next, a polyethylene terephthalate film (thickness: 12 μm, with a polyester-based adhesive applied) is placed on the phosphor layer with the adhesive layer side facing down to adhere the transparent protective film. Formed.

Thus, a radiation image conversion panel composed of the support, the phosphor layer and the transparent protective film was produced.

[Comparative Example 4] The method of Example 1 except that 2 g of a methyl ethyl ketone solution of a bisphenol A type epoxy resin (average molecular weight: 900) was used in place of 0.04 g of the methyl ethyl ketone solution of diphenyldecyl phosphite in Comparative Example 4. By performing the same treatment, a radiation image conversion panel composed of a support, a phosphor layer and a transparent protective film was manufactured.

The radiation image conversion panels (Example 4 and Comparative Example 4) were irradiated with X-rays having a tube voltage of 80 KVp, and then excited with He-Ne laser light (wavelength: 632.8 nm) to measure the sensitivity.

Next, the radiation image conversion panels obtained in Example 4 and Comparative Example 4 were evaluated by a deterioration characteristic test.

As for the deterioration characteristic test, the panel is at room temperature of 60 ° C and relative humidity of RH80.
% Atmosphere for 7 days.

After standing, the sensitivity of each panel was measured in the same manner as above. The results are shown in Table 3. Note that the sensitivity is represented by setting the sensitivity of each panel before the deterioration characteristic test (before standing) to 100, and the results of Example 1 are also shown.

As is apparent from Table 3, the radiation image conversion panel of the present invention (Example 4) containing the phosphorous ester and the epoxy group-containing compound in the phosphor layer contained only the phosphorous ester in the phosphor layer of the present invention. The sensitivity was still higher than that of the image conversion panel (Example 1) and the radiation image conversion panel containing only the epoxy group-containing compound listed for comparison (Comparative Example 4).

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the layer thickness of the phosphor layer and the relative sensitivity for the radiation image conversion panel containing the phosphite of the present invention (curve 1) and the conventional radiation image conversion panel (curve 2). is there.

Claims (17)

[Claims] 1. A radiation image conversion panel comprising a support and a phosphor layer comprising a binder, which is provided on and supports the stimulable phosphor in a dispersed state, wherein the stimulable phosphor is A radiation image conversion panel which is a phosphor containing iodine, wherein the phosphor layer contains at least one compound selected from the group consisting of phosphorous acid esters, organic tin compounds and organic acid metal salts. 2. At least one compound selected from the group consisting of the phosphorous acid ester, the organic tin compound and the organic acid metal salt is contained in the phosphor layer in an amount of 0.0 to 0.1% with respect to the stimulable phosphor.
The radiation image conversion panel according to claim 1, wherein the radiation image conversion panel is contained in the range of 03 to 03% by weight. 3. At least one compound selected from the group consisting of phosphite ester, organotin compound and organic acid metal salt is contained in the phosphor layer in an amount of 0.0
The radiation image conversion panel according to claim 2, wherein the radiation image conversion panel is contained in the range of 03 to 0.3% by weight. 4. The phosphite is represented by the following general formula [I]:
The radiation image conversion panel according to claim 1, which is a compound represented by the formula (1) and / or a compound represented by the general formula (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 these may be the same or different from each other; X ¹ is composed of a carbon atom, an oxygen atom and a hydrogen atom. Is the basis) 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 these may be the same or different from each other; Y ¹ , Y ² , Y ³ and Y ⁴ are respectively An alkyl group, an aryl group, a fatty acid, a fatty acid derivative, a mercaptan or a mercapto acid, and these may be the same or different from each other; X ² is an oxygen atom, a sulfur atom or maleic acid; and 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 a positive integer) 7. A divalent europium-activated alkaline earth metal fluoride halide phosphor containing iodine, and a divalent europium-activated alkaline earth metal halide phosphor containing iodine as the stimulable phosphor. , A rare earth element-activated rare earth oxyhalide-based phosphor containing iodine, and a bismuth-activated alkali metal halide-based phosphor containing iodine, wherein the phosphor is at least one phosphor selected from the group consisting of: A radiation image conversion panel according to claim 1. 8. A radiation image conversion panel comprising a support and a phosphor layer comprising a binder which is provided on and supports the stimulable phosphor in a dispersed state, wherein the stimulable phosphor is A phosphor containing iodine, wherein the phosphor layer contains a compound having an epoxy group, and at least one compound selected from the group consisting of phosphorous acid esters, organic tin compounds and organic acid metal salts. Radiation image conversion panel. 9. At least one compound selected from the group consisting of the above phosphite ester, an organic tin compound and an organic acid metal salt is contained in the phosphor layer in an amount of 0.0 or more with respect to the stimulable phosphor.
The radiation image conversion panel according to claim 8, wherein the radiation image conversion panel is contained in the range of 001 to 3% by weight. 10. A phosphor layer containing at least one compound selected from the group consisting of phosphorous acid esters, organic tin compounds and organic acid metal salts in an amount of 0.1.
The radiation image storage panel according to claim 9, wherein the radiation image storage panel is contained in the range of 003 to 0.3% by weight. 11. A compound represented by the following general formula [I] and / or a general formula [II]
The radiation image conversion panel according to claim 8, which is a compound represented by the formula (9). (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 these may be the same or different from each other; X ¹ is composed of a carbon atom, an oxygen atom and a hydrogen atom. Is the basis) 12. The radiation image storage panel according to claim 8, wherein the organotin compound is 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 these may be the same or different from each other; Y ¹ , Y ² , Y ³ and Y ⁴ are respectively An alkyl group, an aryl group, a fatty acid, a fatty acid derivative, a mercaptan or a mercapto acid, and these may be the same or different from each other; X ² is an oxygen atom, a sulfur atom or maleic acid; and n is 0 or an integer of 1 or more) 13. The organic acid metal salt according to the following general formula [IV]:
The radiation image conversion panel according to claim 8, which is a compound represented by the formula (9). (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 a positive integer) 14. The compound having an epoxy group is contained in the phosphor layer in an amount of 0.001 to 10% by weight based on the stimulable phosphor.
The radiation image conversion panel according to claim 8, wherein the radiation image conversion panel is included in the range. 15. The compound having an epoxy group is contained in the phosphor layer in an amount of 0.03 to 3% by weight based on the stimulable phosphor. 1
The radiation image conversion panel according to item 4. 16. The compound having an epoxy group is 1,
The radiation image storage panel according to claim 8, which is at least one compound selected from the group consisting of 2-epoxypropane, 1,2-epoxybutane, and an epoxy resin. 17. The stimulable phosphor is a divalent europium-activated alkaline earth metal fluoride halide phosphor containing iodine, or a divalent europium-activated alkaline earth metal halide phosphor containing iodine. , A rare earth element-activated rare earth oxyhalide-based phosphor containing iodine, and a bismuth-activated alkali metal halide-based phosphor containing iodine, wherein the phosphor is at least one phosphor selected from the group consisting of: A radiation image conversion panel according to claim 8.