JP2005330490A - Stimulable phosphor and its preparation process, and radiation image transformation panel and its preparation process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stimulable phosphor, which exhibits no deterioration of its performance due to moisture absorption and can be used in a fine condition for a long period, and its preparation process, and also to provide a radiation image conversion panel and its preparation process. <P>SOLUTION: The preparation process of a stimulable phosphor comprises following steps: (A) a step of forming a precursor of the stimulable phosphor; (B) a step of firing the above precursor in the presence of a metal oxide and (C) a step of coating the above fired precursor with a silane coupling agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photostimulable phosphor and a method for producing the same, and a radiation image conversion panel and a method for producing the same. More specifically, the photostimulability that can be used in a good condition for a long time with little performance deterioration due to moisture absorption. The present invention relates to a phosphor, a manufacturing method thereof, a radiation image conversion panel, and a manufacturing method thereof.

  Radiation images such as X-ray images are often used for disease diagnosis and the like. In order to obtain this X-ray image, the X-ray that has passed through the subject is irradiated onto the phosphor layer (phosphor screen), thereby generating visible light, which is the same as when taking a normal picture with a silver salt. So-called radiographs, which are developed by irradiating a film using a film, are used. However, in recent years, a method has been devised in which an image is directly extracted from a phosphor layer without using a film coated with silver salt.

  In this method, radiation transmitted through the subject is absorbed by the phosphor, and then the phosphor is excited by light or thermal energy, for example, so that the radiation energy accumulated by the absorption is emitted as fluorescence. There is a method for detecting and imaging this fluorescence. Specifically, for example, a radiation image conversion method using a stimulable phosphor as described in US Pat. No. 3,859,527 and Japanese Patent Application Laid-Open No. 55-12144 is known.

  This method uses a radiation image conversion panel containing a stimulable phosphor. The radiation transmitted through the subject is applied to the photostimulable phosphor layer of this radiation image conversion panel to support the radiation transmission density of each part of the subject. The radiation energy accumulated in the stimulable phosphor is then accumulated by chronologically exciting the stimulable phosphor with electromagnetic waves (excitation light) such as visible light and infrared light. The energy is emitted as stimulated light emission, a signal based on the intensity of this light is photoelectrically converted, for example, to obtain an electrical signal, and this signal is reproduced as a visible image on a recording material such as a photosensitive film or a display device such as a CRT. Is.

  According to the above-mentioned radiographic image recording / reproducing method, a radiographic image with a large amount of information can be obtained with a much smaller exposure dose than in the case of radiographic method using a combination of conventional radiographic film and intensifying screen. There is an advantage that you can.

  As described above, the stimulable phosphor is a phosphor that exhibits stimulating light emission when irradiated with radiation and then irradiated with excitation light. In practice, the stimulable phosphor has a wavelength of 300 to 300 by excitation light having a wavelength in the range of 400 to 900 nm. A phosphor that exhibits stimulated emission in the wavelength range of 500 nm is generally used.

  Examples of stimulable phosphors conventionally used in radiation image conversion panels include the following.

Examples of stimulable phosphors conventionally used in radiation image conversion panels are (1) (Ba _1-X , M 2 ⁺ X) FX: yA described in JP-A No. 55-12145. (Where M ²⁺ is at least one of Mg, Ca, Sr, Zn and Cd, X is at least one of Cl, Br, and I, A is Eu, Tb, Ce, Tm, Dy, Pr, At least one of Ho, Nd, Yb, and Er, and x is 0 ≦ x ≦ 0.6 and y is 0 ≦ y ≦ 0.2. Alkaline earth metal fluoride halide phosphors; and the phosphors may contain the following additives: X ', BeX described in JP-A-56-74175 ^{'', M 3 X ''} '3 ( However, X', X '', Hoyo X '''is at least one of each of Cl, Br and I, M3 is a trivalent metal);

_BeO as described in JP 55-160078 _{discloses, BgO, CaO, SrO, BaO} , ZnO, Al 2 O 3, Y 2 O 3, La 2 O 3, In 2 O 3, SiO 2, TiO 2 , ZrO ₂ , GeO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O _5, ThO ₂ and other metal oxides; Zr and Sc described in JP-A-56-116777; JP-A 57- B described in Japanese Patent No. 23673; As and Si described in Japanese Patent Laid-Open No. 57-23675;

  M · L described in JP-A-58-206678 (where M is at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs; L is Sc, Y At least one trivalent metal selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, In, and Tl A calcined product of a tetrafluoroboric acid compound described in JP-A-59-27980; hexafluorosilicic acid, hexafluorotitanic acid and hexafluoro described in JP-A-59-27289; Baked product of monovalent or divalent metal salt of zirconimic acid; NaX ′ described in JP-A-59-56479 (where X ′ is Cl, Br and I) At least one type is); V which are described in JP 59-56480 Publication, Cr, Mn, Fe, transition metals such as Co and Ni;

JP 59-75200 JP ^M 1 ^X that are described in ^{', M' 2 X ''} , M 3 X ''', A ( however, ^{M 1} is Li, Na, K, Rb, and the Cs And M ′ ² is at least one divalent metal selected from the group consisting of Be and Mg; and M ³ is from the group consisting of Al, Ga, In, and Tl. At least one trivalent metal selected; 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. there); JP M1X listed in 60-101173 JP '(wherein, ^{M 1} is located at least one alkali metal selected from the group consisting of Rb and Cs; X' is F, Cl, Br and I At least one halogen selected from the group consisting of:

JP 61-23679 No. ^M 2 are described in JP ^{_{'X' 2 · M 2 '}} X''2 ( however, ^{M 2'} is at least one alkaline earth selected from the group consisting of Ba, Sr and Ca X ′ and X ′ are each at least one halogen selected from the group consisting of Cl, Br and I, and X ′ ≠ X ″); and

LnX ″ ₃ described in Japanese Patent Application No. 60-106752 (where Ln is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm And at least one rare earth element selected from the group consisting of Y, Yb and Lu; X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I);
(2) M ² X ₂ · aM ² ′ ₂ : xEu ²⁺ described in JP-A-60-84381 (where M ² is at least one alkaline earth selected from the group consisting of Ba, Sr and Ca) X and X ′ are at least one halogen selected from the group consisting of Cl, Br and I, and X ≠ X ′; and a is 0.1 ≦ a ≦ 0.0, x is 0 <x ≦ 0.2) divalent europium activated alkaline earth metal halide phosphor represented by the composition formula:

The phosphor may contain the following additives: M ¹ X ″ described in JP-A-60-166379 (where M ¹ is composed of Rb and Cs) At least one alkali metal selected from the group; X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I);

JP 60-221483 Patent KX that publication is described in ^{_{'', MgX '''2}} , M 3 X''''3 ( however, ^{M 3} is Sc, Y, La, from the group consisting of Gd and Lu At least one trivalent metal selected; X ″, X ″ ′ and X ″ ′ ′ are all at least one halogen selected from the group consisting of F, Cl, Br and I);

B described in JP-A-60-228592;
Oxides such as SiO ₂ and P ₂ O ₅ described in JP-A-60-228593;
LiX ″, NaX ″ described in JP-A No. 61-120882 (where X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I);
SiO described in JP-A-61-120883;
SnX ″ ₂ described in JP-A-61-120885 (where X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I);

  CsX ″, SnX ″ ″ 2 described in JP-A-61-235486 (where X ″ and X ″ ′ are at least one selected from the group consisting of F, Cl, Br and I, respectively) Halogen); and

  CsX ″, Ln3 + described in JP-A-61-235487 (where X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I; Ln is Sc, Y , Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, which is at least one rare earth element);

(3) LnOX: xA described in JP-A-55-12144 (where 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 a rare earth element-activated rare earth oxyhalide phosphor represented by a composition formula: 0 <x <0.1;

(4) M ³ OX: xCe described in JP-A-58-69281 (where M ³ is Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, and At least one metal oxide selected from the group consisting of Bi; X is at least one of Cl, Br, and I; x is 0 <x <0.1) Activated trivalent metal oxyhalide phosphor;

(5) M ¹ X: xBi described in Japanese Patent Application No. 60-70484 (where M ¹ is at least one alkali metal selected from the group consisting of Rb and Cs; X is Cl, Br A bismuth-activated alkali metal halide phosphor represented by a composition formula: at least one halogen selected from the group consisting of and I; and x is a numerical value in the range of 0 <x ≦ 0.2.

(6) M ² ₅ (PO ₄ ) ₃ x: xEu ²⁺ described in JP-A-60-141784 (where M ² is at least one alkaline earth selected from the group consisting of Ca, Sr and Ba) X is at least one halogen selected from the group consisting of F, Cl, Br and I; and x is a numerical value in the range of 0 <x ≦ 0.2. Europium activated alkaline earth metal halophosphate phosphor;

(7) M ² ₂ BO ₃ X: xEu ²⁺ described in JP-A-60-157099 (wherein M ² is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba) Yes; 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 alkali Earth metal haloborate phosphors;

(8) M ² ₂ PO ₄ X: xEu ²⁺ described in JP-A-60-157100 (where M ² is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba) Yes; 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 alkali Earth metal halophosphate phosphors;

(9) M ² HX: xEu ²⁺ described in JP-A-60-217354 (wherein M ² is at least one alkaline earth metal selected from the group consisting of Ca, Sr 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 Hydride halide phosphors;

(10) LnX ₃ · aLn′X ′ ₃ : xCe ³⁺ described in JP-A No. 61-21173 (where Ln and Ln ′ are at least selected from the group consisting of Y, La, Gd and Lu, respectively) X and X ′ are each at least one halogen selected from the group consisting of F, Cl, Br and I, and X ≠ X ′; and a is 0.1 <a A numerical value in the range of ≦ 10.0, and x is a numerical value in the range of 0 <x ≦ 0.2).

(11) LnX ₃ · aM ¹ X ′: xCe ³⁺ described in JP-A-61-21182 (where Ln and Ln ′ are at least one selected from the group consisting of Y, La, Gd and Lu, respectively) M ¹ is at least one alkali metal selected from the group consisting of Li, Na, K, Cs and Rb; X and X ′ are at least selected from the group consisting of Cl, Br and I, respectively. 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). Halide phosphors;

(12) LnPO ₄ · aLnX ₃ : xCe ³⁺ described in JP-A No. 61-40390 (where Ln is at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; X is at least one halogen selected from the group consisting of F, Cl, Br and I; and a is a numerical value in the range of 0.1 ≦ a ≦ 10.0, and x is 0 <x ≦ 0.2. A cerium-activated rare earth halophosphate phosphor represented by a composition formula:

(13) CsX: aRbX ′: xEu ²⁺ described in Japanese Patent Application No. 60-78151 (where X and X ′ are at least one halogen selected from the group consisting of Cl, Br and I, respectively) 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). The divalent europium-activated cesium halide and rubidium A phosphor; and

(14) M ² X ₂ · aM ¹ X ′: xEu ²⁺ described in Japanese Patent Application No. 60-78153 (where M ² is at least one alkali selected from the group consisting of Ba, Sr and Ca) M ¹ is at least one alkali metal selected from the group consisting of Li, Rb and Cs; and X and X ′ are at least one halogen selected from the group consisting of Cl, Br and I, respectively. Yes, 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). Fluoride compound;
Can be mentioned.

  Among the photostimulable phosphors described above, a divalent europium activated alkaline earth metal fluoride halide phosphor containing iodine, and a divalent europium activated alkaline earth metal halide phosphor containing iodine. The rare earth element activated rare earth oxyhalide phosphors containing iodine and the bismuth activated alkali metal halide phosphors containing iodine show stimulated luminescence with high brightness.

  Radiation image conversion panels using these photostimulable phosphors, after accumulating radiation image information, release accumulated energy by scanning excitation light, so that radiation images can be accumulated again after scanning and used repeatedly. Is possible. In other words, the conventional radiographic method consumes a radiographic film for each radiographing, whereas in this radiographic image conversion method, the radiographic image conversion panel is used repeatedly, which is advantageous in terms of resource protection and economic efficiency. It is.

  Therefore, it is desirable to provide the radiation image conversion panel with performance that can withstand long-term use without degrading the image quality of the obtained radiation image.

  However, photostimulable phosphors used in the production of radiation image conversion panels generally have a high hygroscopic property, and when they are left in a room under normal climatic conditions, they absorb moisture in the air and deteriorate significantly over time.

  Specifically, for example, when a stimulable phosphor is placed under high humidity, the radiation sensitivity of the phosphor decreases as the absorbed moisture increases. In general, the latent image of the radiation image recorded on the photostimulable phosphor regresses with the passage of time after irradiation, so the intensity of the reconstructed radiation image signal is from radiation irradiation to scanning with excitation light. However, when the stimulable phosphor absorbs moisture, the latent image retraction speed increases.

  Therefore, when a radiation image conversion panel having a photostimulable phosphor that has absorbed moisture is used, the reproducibility of a reproduction signal at the time of reading a radiation image is lowered.

  Conventionally, in order to prevent the deterioration phenomenon due to moisture absorption of the stimulable phosphor, the phosphor layer is covered with a moisture-proof protective layer or a moisture-proof resin film having low moisture permeability. A method for reducing the amount of water to reach, a method using hydrophobic fine particles described in JP-B-62-177500, a method using a silane coupling agent described in JP-B-62-209398, and a titanate coupling agent described in JP-B-2-278196 And the method using silicone oil described in Japanese Patent Publication No. 5-52919 have been devised, but none of them has led to a fundamental solution.

  In addition, it is known that the photostimulable phosphor particles generally have a photostimulability depending on the particle size. JP-A No. 55-163500 discloses an average particle size of 1 to 30 μm. Is preferred. Japanese Patent Publication No. 3-79680 discloses the relationship between the phosphor particle size and characteristic values such as sensitivity, graininess, and sharpness.

  An attempt to control the size and shape of the photostimulable phosphor particles is disclosed in Japanese Patent Application Laid-Open No. 7-233369 by a liquid phase method. Here, a rare earth activated alkaline earth metal fluoride halide system is disclosed as a conventional method. The photostimulable phosphor can be produced by dry-mixing alkaline earth metal fluorides of raw material compounds, alkaline earth metal halides other than fluoride, rare earth halides, ammonium fluoride, or the like together, or A method is disclosed in which a rare earth activated alkaline earth metal fluoride halide photostimulable phosphor is precipitated in an aqueous solution, while suspended and mixed in an aqueous medium, then fired and pulverized.

  The liquid phase method for precipitating rare earth-activated alkaline earth metal fluoride halide-based stimulable phosphors in the above aqueous solution can produce phosphor particles with a small particle size without deterioration of performance due to grinding. Became.

  However, since the sensitivity is high and the particle size is reduced, deterioration due to moisture has become more problematic than before. This deterioration starts from the moment when the phosphor particles are exposed to the atmosphere after firing, and in order to prevent this, there is a method of storing the phosphor particles in an environment cut off from the atmosphere after firing. It is practically difficult to perform all the steps in the production of the phosphor plate under such an environment.

  The object of the present invention is to solve the above-mentioned problems in a radiation image conversion panel using a photostimulable phosphor, and to exhibit photostimulable fluorescence that can be used in a good condition for a long time without performance deterioration due to moisture absorption. An object of the present invention is to provide a body, a manufacturing method thereof, a radiation image conversion panel, and a manufacturing method thereof.

The present invention for solving the above problems has the following configuration.
1. In the manufacturing method of a photostimulable phosphor, the manufacturing method of the photostimulable phosphor characterized by having the following process.
(A) producing a stimulable phosphor precursor;
(B) firing the precursor in the presence of a first metal oxide; and (C) coating the fired precursor with a silane coupling agent.

2. 2. The method for producing a photostimulable phosphor according to the above 1, wherein the silane coupling agent has a mercapto group.

3. 2. The method for producing a photostimulable phosphor according to 1, wherein the silane coupling agent has a vinyl group.

4). In the manufacturing method according to 1 or 2, the step (C) is a step of coating the photostimulable phosphor with 0.1% by weight or more and 5% by weight or less of a silane coupling agent. A method for producing a photostimulable phosphor.

5). 5. The method for producing a photostimulable phosphor according to any one of 1 to 4, wherein the metal oxide has been subjected to a hydrophobic treatment.

6). 6. The method for producing a photostimulable phosphor according to any one of 1 to 5, wherein the metal oxide is at least one selected from silica, alumina, and titanium oxide.

7). 7. The manufacturing method according to any one of 1 to 6, wherein the step (C) is a step of coating the calcined precursor with a silane coupling agent and a second metal oxide. A method for producing a stimulable phosphor.

8). In the manufacturing method according to any one of 1 to 7, the metal oxide in the step (B) is alumina, and the second metal oxide in the step (C) is silica. A method for producing a photostimulable phosphor.

9. 9. The method according to any one of 1 to 8, wherein the photostimulable phosphor has at least a Ba atom, an F atom, an X atom, and an Ln atom (where X is F, Cl, Br, I, At least one of At, Yb, and No, and Ln is at least one of Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er, and Yb.) A method for producing a photostimulable phosphor.

10. 9. The method according to any one of 1 to 8, wherein the photostimulable phosphor is represented by the following general formula (I).

Formula (I)
(Ba _1-x M ¹ ) FX: _y M ² , _z L _n
(However, M ¹ : at least one alkaline earth metal selected from the group consisting of Mg, Ca, Sr, Zn and Cd M ² : at least one alkali selected from the group consisting of Li, Na, K, Rb and Cs Metal X: at least one halogen selected from the group consisting of Cl, Br and I Ln: at least selected from the group consisting of Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er and Yb One kind of rare earth elements x, y, and z are 0 ≦ x ≦ 0.6, 0 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.2, respectively.
Represents each. )

11. A photostimulable phosphor obtained by the production method according to any one of 1 to 10 above.

12 12. A radiation image conversion panel having a phosphor layer containing a photostimulable phosphor, comprising the photostimulable phosphor as described in 11 above.

13. Generating a stimulable phosphor precursor; firing the precursor in the presence of a metal oxide; coating the fired precursor with a silane coupling agent; And a step of producing a phosphor layer containing the photostimulable phosphor. A method for producing a radiation image conversion panel, comprising:

The following are mentioned as reference examples of the present invention.
(1) A method for producing a photostimulable phosphor, which comprises the following steps in the method for producing a photostimulable phosphor.
(A) a step of producing a photostimulable phosphor; and (b) a step of coating the photostimulable phosphor with a metal oxide and a silane coupling agent.

(2) The method for producing a stimulable phosphor according to (1), wherein the silane coupling agent has a mercapto group.

(3) In the manufacturing method as described in said (1), the said silane coupling agent has a vinyl group, The manufacturing method of the photostimulable phosphor characterized by the above-mentioned.

(4) In the manufacturing method according to (1), (2), or (3), the step (b) is performed in an amount of 0.05% by weight to 10% by weight with respect to the photostimulable phosphor. A method for producing a photostimulable phosphor, which is a step of coating the metal oxide and the photostimulable phosphor with 0.1% by weight or more and 5% by weight or less of a silane coupling agent.

(5) The method for producing a photostimulable phosphor according to any one of (1) to (4), wherein the metal oxide is subjected to a hydrophobic treatment.

(6) The photostimulable phosphor according to any one of (1) to (5) above, wherein the metal oxide is at least one selected from silica, alumina, or titanium oxide. Method.

(7) In the production method according to any one of (1) to (6), the photostimulable phosphor has at least a Ba atom, an F atom, an X atom, and an Ln atom (provided that X is F , Cl, Br, I, At, Yb and No, and Ln is Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er and Yb. And at least one of the photostimulable phosphors.

(8) In the manufacturing method according to any one of (1) to (6), the stimulable phosphor is represented by the following general formula (I): Production method.

Formula (I)
(Ba _1-x M ¹ ) FX: _y M ² , _z L _n
(However, M ¹ : at least one alkaline earth metal selected from the group consisting of Mg, Ca, Sr, Zn and Cd M ² : at least one alkali selected from the group consisting of Li, Na, K, Rb and Cs Metal X: at least one halogen selected from the group consisting of Cl, Br and I Ln: at least selected from the group consisting of Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er and Yb One kind of rare earth elements x, y, and z are 0 ≦ x ≦ 0.6, 0 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.2, respectively.
Represents each. )

(9) A photostimulable phosphor obtained by the production method according to any one of (1) to (8) above.

(10) A step of generating a photostimulable phosphor, a step of coating the photostimulable phosphor with a metal oxide and a silane coupling agent, and a phosphor layer containing the coated photostimulable phosphor And a step of producing the radiation image conversion panel.

  ADVANTAGE OF THE INVENTION According to this invention, the photostimulable phosphor which can be used in a favorable state for a long time without the performance deterioration by moisture absorption, its manufacturing method, a radiation image conversion panel, and its manufacturing method can be provided.

Hereinafter, the present invention will be described in detail.
The photostimulable phosphor in the present invention may be any of (1) to (14) described in the prior art.

  The photostimulable phosphor may have any shape such as plate-like particles, spherical particles, hexahedral particles, and tetrahedral particles.

  In the present invention, the photostimulable phosphor precursor refers to a substance that hardly exhibits stimulable luminescence or instantaneous luminescence. For example, it refers to a state in which the substance of the general formula (I) has not passed a high temperature of 600 ° C. or higher. Further, the stimulable phosphor precursor in the solid-phase method is a stimulable phosphor material itself, a mixture of stimulable phosphor materials, or a high temperature of 600 ° C. or higher for these substances. Say state.

  While investigating the phenomenon of sensitivity degradation due to moisture absorption of stimulable phosphors, the present inventors have found that performance degradation is caused by phosphor deliquescence and phosphor modification due to moisture absorption. This phenomenon is particularly likely to occur with stimulable phosphors containing X atoms. Examples of stimulable phosphors containing X atoms include general formula (I).

Formula (I)
(Ba _1-x M ¹ ) FX: _y M ² , _z L _n
(However, M ¹ : at least one alkaline earth metal selected from the group consisting of Mg, Ca, Sr, Zn and Cd M ² : at least one alkali selected from the group consisting of Li, Na, K, Rb and Cs Metal X: at least one halogen selected from the group consisting of Cl, Br and I Ln: at least selected from the group consisting of Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er and Yb One kind of rare earth elements x, y, and z are 0 ≦ x ≦ 0.6, 0 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.2, respectively.
Represents each. )

  Therefore, preventing either deliquescence or alteration is not a fundamental solution. Accordingly, it has been found that the above-described problem can be solved by the above-described configuration of the present invention by intensive studies to prevent both deliquescence and alteration.

  The above-mentioned deliquescence means a phenomenon in which phosphor particles take water vapor in the air to make an aqueous solution by themselves, and alteration means that the fluorescence characteristics of the phosphor itself change due to water vapor in the air, although it does not deliquesce. . Although the mechanism of alteration is not clear, structural changes inside the phosphor particles are considered.

  The present invention is effective in preventing both deliquescence and alteration, but it is also effective for phosphor particles having no deliquescence properties. The effect of the present invention is to prevent phosphor alteration and deliquescence.

  The hygroscopic property of the phosphor is considered to occur due to various causes including capillary aggregation, but once water vapor is generated between the phosphor particles as water droplets, performance degradation occurs due to deliquescence.

In the present invention, this deliquescence can be suppressed by the configuration of (2) below. Note that this configuration (1) can suppress this deliquescence, but this (1) is a reference example of the present invention.
(1) A stimulable phosphor is coated with a metal oxide and a silane coupling agent.
(2) The stimulable phosphor is calcined in the presence of the first metal oxide and then coated with a silane coupling agent, or the stimulable phosphor is present in the presence of the first metal oxide. After the precursor is fired, it is coated with a silane coupling agent and a second metal oxide.

Hereinafter, these methods will be described.
About (1) (reference example)
The coating treatment with metal oxide fine particles in the present invention is presumed to have an effect of preventing the occurrence of such deliquescence. In particular, the effect is large in the case of metal oxide particles that have been hydrophobized. However, the same effect can be given to metal oxide fine particles by treating the phosphor with metal oxide particles and then treating with a silane coupling agent.

  A silane coupling agent is effective for preventing the phosphor from being altered, but it has been difficult to directly form a silicon-containing film of the phosphor particles and the silane coupling agent on the phosphor particles.

  In the present invention, in order to perform the coating treatment of the second metal oxide particles and the surface treatment with the silane coupling agent, the periphery of the metal oxide particles in which the silicon-containing film by the silane coupling agent is dispersed on the phosphor particles is disposed. It is considered that the silane coupling agent functions effectively to form a continuous phase so as to fill.

  It is effective to perform the coating with the second metal oxide particles and the surface treatment with the silane coupling agent simultaneously or in the order of the surface treatment with the silane coupling agent after the coating of the metal oxide particles.

  The second metal oxide particles used in the present invention are preferably composed of one or more of silica, alumina, and titanium oxide and having a particle size of 2 to 50 nm. Those having a particle size of 2 nm or less are difficult to obtain industrially, and if it exceeds 50 nm, it is difficult to satisfactorily coat the surface of the phosphor particles.

  Examples of such metal oxide particles include dry process metal oxides such as silica, alumina, and titanium dioxide by flame hydrolysis and arc processes, as well as wet processes obtained by decomposition with a salt acid such as sodium silicate. Those obtained by various production methods such as those obtained by hydrolysis of metal oxides and organogels are used.

  Examples of the method for hydrophobizing metal oxide particles include a treatment with a silane coupling agent such as dimethylchlorosilane, hexamethyldisilane, and octyltrimethoxysilane, and a treatment with silicone oil. Also, metal oxide particles that have already been hydrophobized can be obtained industrially.

  In the present invention, the hydrophobized metal oxide particles refer to particles having a degree of hydrophobicity (MW value) of greater than 20 by the methanol wettability method.

  Any ordinary method can be used to mix an appropriate amount of metal oxide with phosphor particles having an average particle size of several μm to several tens of μm. However, a turbuler shaker mixer (Shinmaru Enterprises) Using a mixing device such as the one manufactured by Kogyo Co., Ltd., and a method in which phosphor particles are gradually added to the total amount of metal oxide, and a metal oxide dispersion having a concentration of 0.5 to 10.0 wt% Among them, the method of filtering and drying the phosphor particles after stirring is preferable from the viewpoint of uniform coating of the particles.

  The silane coupling agent used in the present invention is represented by the general formula (1)

It is a compound represented by these.

  In the formula, R represents an aliphatic or aromatic hydrocarbon group, which may contain an unsaturated group (for example, a vinyl group), ROR'-, RCOOR'-RNHR'- (R is an alkyl group, aryl Group R ′ may be an alkylene group, an arylene group) or other substituents.

X ₁ , X ₂ and X _{3 each} represents an aliphatic or aromatic hydrocarbon, an acyl group, an amide group, an alkoxy group, an alkylcarbonyloxy group, an epoxy group, a mercapto group or a halogen atom, and X ₁ , X ₂ , X ₃ may be the same or different from each other. However, at least one is a group other than hydrocarbon. X ₁ , X ₂ and X ₃ are preferably groups that undergo hydrolysis.

  Specific examples of the silane coupling agent include methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropylmethyldichlorosilane, γ -Chloropropylmethyldimethoxysilane, γ-chloropropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl)- γ-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane , Γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ- (2-aminoethyl) amino Examples thereof include propylmethyldimethoxysilane, γ-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane / hydrochloride, and aminosilane compound. . Of these, vinyl type, mercapto type, glycidoxy type, and methacryloxy type are particularly preferable, and mercapto type is more preferable.

  Particularly preferred silane coupling agents include γ-mercaptopropyltrimethoxysilane ([1] below), 3-mercaptopropylmethyldimethoxysilane, mercaptopropyltriethoxysilane, and the like, and similar to these mercapto silane coupling agents. 1-mercaptomethyl-1,1,3,3,3-pentamethyldisiloxane, 1- (3-mercaptopropyl) -1,1,3,3,3-pentamethyldisiloxane Etc.

  According to the study by the present inventors, the compound containing a mercapto group has an effect of preventing discoloration of the stimulable phosphor, and the above-mentioned particularly preferable silane coupling agent and siloxane are coloring of the phosphor in addition to the moisture-proof effect. The effect of preventing a decrease in sensitivity due to is also added. In particular, the effect of preventing discoloration of a compound containing a mercapto group is remarkable when the phosphor contains iodine in the structure, and effectively prevents yellowing of the phosphor due to free iodine.

  In attaching the silane coupling agent to the phosphor particles coated with metal oxide particles, a known method can be used. For example, using a Hensyl mixer, a dry method in which a silane coupling agent is dropped or sprayed while stirring and mixing phosphor particles, stirring while dropping a silane coupling agent on a slurry-like phosphor, and the phosphor is precipitated after the dropping is completed. A slurry method in which the phosphor is dried after filtration and the residual solvent is removed, the phosphor is dispersed in the solvent, and after adding a silane coupling agent and stirring, the solvent is evaporated to form an adhesion layer Or a method in which a silane coupling agent is added to the stimulable phosphor coating dispersion. The silane coupling agent is preferably dried at 60 ° C. to 130 ° C. for about 10 to 200 minutes to ensure the reaction with the phosphor.

  The effect of the present invention appears remarkably when the coating with metal oxide particles and the surface treatment with a silane coupling agent are performed simultaneously.

  As an example of such a treatment method, phosphor particles immediately after firing in a dispersion of metal oxide particles and a silane coupling agent are disintegrated in the liquid, and simultaneously with the disintegration of the phosphor, Examples include a method of performing filtration and drying after surface treatment with a coating and a silane coupling agent, and a method of adding metal oxide particles and a silane coupling agent to a coating dispersion for a stimulable phosphor layer. It is not limited to these.

  In the present invention, when the amount of the metal oxide exceeds 10% with respect to the phosphor, the sensitivity is lowered, and when it is less than 0.05%, the effect of the present invention is halved.

  On the other hand, when the amount of the silane coupling agent is more than 5% with respect to the amount of the phosphor, the sensitivity is lowered, the coating film is hardened, and cracks are generated on the film surface. If it is 0.1% or less, the effect of the present invention is halved.

Regarding (2) (the present invention)
First, an example using a silane coupling agent will be described. After firing the precursor particles before firing with the first metal oxide particles according to the present invention, surface treatment with a silane coupling agent yields phosphor particles with high moisture resistance, dispersion, liquid preparation, Even if it is applied as a phosphor layer on the support through the application step, the effect of improving the moisture resistance of the particles is maintained. It is considered that the phosphor particles and the metal oxide particles are bonded by an electric force. However, if a force greater than this electric force is applied during the dispersion, preparation, and coating process, the phosphor particles of the metal oxide Although peeling is considered to occur, in other words, if a silane coupling agent is used in the method of (2), this peeling can be suppressed, and a moisture resistance effect can be obtained even after application.

  In particular, the amount of the first metal oxide is determined within a range that does not impair the firing efficiency, and the phosphor particles are coated with the insufficient amount of the second metal oxide after firing, followed by treatment with a silane coupling agent. It is possible to obtain an effect that it is possible to suppress a decrease in light emission characteristics due to a decrease in efficiency.

  It is unclear why the metal oxide particles do not peel from the phosphor particles during the dispersion, preparation, and coating process, but it is assumed that some bonding occurs between the phosphor particles and the metal oxide particles during firing. Is done.

  The amount of the first metal oxide in the present invention is preferably alumina in terms of preventing sintering of phosphor particles, and is preferably 0.01 to 2.0% by weight with respect to the amount of phosphor precursor in terms of firing efficiency. .

  In addition, when alumina is used as the first metal oxide, the moisture resistance of the phosphor is further improved when silica is used as the second metal oxide. The reason why the moisture resistance is further improved by silica is not clear, but it is presumed that since the charging characteristics are different from those of alumina, a strong electric force works with the alumina particles immobilized on the phosphor surface.

  The particle diameter of the metal oxide particles used in the present invention is preferably 2 to 50 nm. Those having a particle size of less than 2 nm are difficult to obtain industrially, and if it exceeds 50 nm, it is difficult to satisfactorily coat the surface of the phosphor particles.

  In the present invention, when the total amount of the metal oxide is 10% or less with respect to the phosphor, the decrease in sensitivity can be reduced, and when it is more than 0.01%, the effect of the present invention can be further improved.

  Further, when the amount of the silane coupling agent is 5% or less with respect to the amount of the phosphor, the decrease in sensitivity can be reduced, and the coating film is hard to be hardened and the occurrence of cracks on the film surface can be reduced. On the other hand, if it exceeds 0.1%, the effect of the present invention can be further improved.

  The metal oxide used in this embodiment (2) is the same as the metal oxide used in the above embodiment (1). Further, the first metal oxide and the second metal oxide may be the same material or different materials.

(Panel creation, phosphor layer, coating process, support, protective layer)
As the support used in the radiation image conversion panel of the present invention, various polymer materials, glass, metal and the like are used. In particular, a material that can be processed into a flexible sheet or web is suitable for handling as an information recording material, and in this respect, cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film Further, a plastic film such as a polycarbonate film, a metal sheet of aluminum, iron, copper, chromium or the like or a metal sheet having a coating layer of the metal oxide is preferable.

  The layer thickness of the support varies depending on the material of the support used, but is generally 3 μm to 1000 μm, and more preferably 80 μm to 500 μm from the viewpoint of handling.

  The surface of these supports may be a smooth surface, or may be a mat surface for the purpose of improving the adhesion to the photostimulable phosphor layer.

  Further, these supports may be provided with an undercoat layer on the surface on which the photostimulable phosphor layer is provided for the purpose of improving the adhesion to the photostimulable phosphor layer.

  Examples of binders used in the stimulable phosphor layer in the present invention include proteins such as gelatin, polysaccharides such as dextran, or natural high molecular substances such as gum arabic; and polyvinyl butyral, polyvinyl acetate, Represented by synthetic polymer materials 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. Can be mentioned.

  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 by a crosslinking agent. The photostimulable phosphor layer can be formed on the undercoat layer by the following method, for example.

  First, a stimulable phosphor, a compound such as a phosphite for preventing yellowing, and a binder are added to a suitable solvent, and these are mixed well to combine the phosphor particles and the compound in the binder solution. A coating solution in which particles are uniformly dispersed is prepared.

  Examples of the binder used in the present invention include proteins such as gelatin, polysaccharides such as dextran or gum arabic, polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethyl cellulose, vinylidene chloride / vinyl chloride copolymer, polymethyl methacrylate, chloride. A film-forming binder usually used for layer construction such as vinyl / vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol and the like is used. Generally, the binder is used in the range of 0.01 to 1 part by weight with respect to 1 part by weight of the stimulable phosphor. However, in terms of sensitivity and sharpness of the obtained radiation image conversion panel, it is preferable that the amount of the binder is small, and the range of 0.03 to 0.2 parts by weight is more preferable in view of the ease of application.

  The mixing ratio of the binder to the stimulable phosphor in the coating solution (however, if the binder is an epoxy group-containing compound, it is equal to the ratio of the compound to the phosphor) is the intended radiation image conversion. Although it varies depending on the characteristics of the panel, the type of phosphor, the amount of the epoxy group-containing compound added, etc., generally examples of solvents for preparing the bonding coating solution include methanol, enotal, 1-propanol, 2-propanol, and n-butanol. Lower alcohols such as methylene chloride, ethylene chloride and other chlorine atom-containing hydrocarbons; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate and butyl acetate; Ethylene glycol ethyl ether, ethylene glycol monomethyl ether Ethers such as ether: toluene; and can include mixtures thereof.

  Examples of the solvent used for the preparation of the stimulable phosphor layer coating solution include lower alcohols such as methanol, ethanol, isopropanol and n-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, ketones such as cyclohexanone, methyl acetate, Esters of lower fatty acids and lower alcohols such as ethyl acetate and n-butyl acetate, ethers such as dioxane, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, aromatic compounds such as triol and xylol, methylene chloride, ethylene chloride, etc. Examples thereof include halogenated hydrocarbons and mixtures thereof.

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

  Dispersing agents such as stearic acid, phthalic acid, caproic acid, and lipophilic surfactants for the purpose of improving the dispersibility of stimulable phosphor layer phosphor particles in the stimulable phosphor layer coating solution. May be mixed. Moreover, you may add the plasticizer with respect to a binder as needed. Examples of the plasticizer include phthalic acid esters such as diethyl phthalate and dibutyl phthalate, aliphatic dibasic acid esters such as diisodecyl succinate and dioctyl adipate, ethyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate And glycolic acid esters.

  The coating liquid prepared as described above is then uniformly applied to the surface of the undercoat layer to form a coating film of the coating liquid. This coating operation can be performed by using a normal coating means, for example, a doctor blade, a roll coater, a knife coater or the like.

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

  The stimulable phosphor layer coating solution is prepared using a dispersing device such as a ball mill, a sand mill, an attritor, a three-roll mill, a high-speed impeller disperser, a Kady mill, and an ultrasonic disperser. The prepared coating solution is applied on a support using a coating solution such as a doctor blade, a roll coater, or a knife coater, and dried to form a photostimulable phosphor layer.

  The film thickness of the stimulable phosphor layer of the radiation image conversion panel of the present invention is the characteristics of the intended radiation image conversion panel, the type of stimulable phosphor, the mixing ratio of the binder and the stimulable phosphor, etc. Depending on the case, it is preferably selected from the range of 10 μm to 1000 μm, more preferably selected from the range of 10 μm to 500 μm.

  A phosphor sheet having a phosphor layer coated on a support is cut into a predetermined size. Any general method can be used for cutting, but a decorative cutting machine, a punching machine, or the like is preferable in terms of workability and accuracy.

  The phosphor sheet cut into a predetermined size is generally sealed with a moisture-proof protective film. Examples of the sealing method include a method in which a phosphor sheet is sandwiched between upper and lower moisture-proof protective films, and a peripheral portion is heated and fused with an impulse sealer, or a laminating method in which pressure is heated between two heated rollers. Etc.

  In the method of heat-sealing with the above impulse sealer, heat-sealing under a reduced pressure environment is more preferable in terms of preventing displacement of the phosphor sheet in the moisture-proof protective film and eliminating moisture in the atmosphere.

The following examples illustrate the invention.
Example 1
To synthesize the stimulable phosphor precursor of europium activated barium, BAI2 solution (1.75mol / l) 2500ml and EuBr ₃ aqueous solution (0.067mol / l) 125ml were charged into a reaction vessel . The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. 250 ml of an aqueous ammonium fluoride solution (8 mol / l) was poured into the reaction mother liquor using a roller pump to form a precipitate. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was separated by filtration, washed with methanol, and then vacuum dried to obtain europium activated barium fluoroiodide crystals. This was filled in a quartz boat and baked at 850 ° C. for 2 hours in a hydrogen gas atmosphere using a tube furnace to obtain europium-activated barium fluoroiodide phosphor particles.

Next, the phosphor was immersed in an ethanol dispersion liquid to which metal oxide particles and a silane coupling agent were added at the ratio shown in Table 1 with respect to the obtained phosphor to form a slurry, and then pulverized to 80 ° C. And dried for 3 hours. After drying, classification was performed to obtain particles having an average particle diameter of 7 μm.
The metal oxide particles and silane coupling agents used at this time are as follows.

<Metal oxide particles>
A1: Silica particle diameter 12nm
A2: Hydrophobized silica particles (manufactured by Nippon Aerosil Co., Ltd .: octylsilane-treated product)
A3: Alumina particles, particle size 13nm
A4: Titanium dioxide particles, particle size 21 nm

<Silane coupling agent>
B1: γ-mercaptopropyltrimethoxysilane B2: γ-mercaptopropylmethyldimethoxysilane B3: vinyltriethoxysilane B4: γ-glycidoxypropyltrimethoxysilane B5: n-hexyltriethoxysilane B6: γ-isocyanatopropyltri Ethoxysilane B7: Methyltrimethoxysilane

Next, an example of manufacturing a radiation image conversion panel is shown.
As the phosphor layer-forming material, 427 g of the europium-activated barium fluoroiodide phosphor obtained above, 15.8 g of polyurethane resin (Desmolac 4125, manufactured by Sumitomo Bayer Urethane Co., Ltd.), 2.0 g of bisphenol A type epoxy resin, methyl ethyl ketone -It added to the toluene (1: 1) mixed solvent, it disperse | distributed with the propeller mixer, and the coating liquid with a viscosity of 25-30PS was adjusted. This coating solution was applied onto an undercoated polyethylene terephthalate film using a doctor blade, and then dried at 100 ° C. for 15 minutes to form a phosphor layer having a thickness of 230 μm.

  A phosphor plate was prepared by cutting the coated sample into a 10 cm × 10 cm square.

Example 2
To synthesize the stimulable phosphor precursor of europium activated barium, BAI2 solution (4.0mol / l) 2850ml and EuI ₃ solution (0.2mol / l) 90ml, and water 60ml Placed in reactor. The reaction mother liquor in this reactor was kept at 60 ° C. with stirring. 720 ml of an aqueous HF solution (5.0 mol / l) was injected into the reaction mother liquor using a roller pump to produce a precipitate. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was separated by filtration, washed with isopropanol, and then vacuum dried to obtain europium activated barium fluoroiodide crystals. When the obtained crystal was observed with a scanning electron microscope, it was a tetrahedral shape. Using this crystal, a phosphor plate was prepared according to Table 2 in the same manner as in Example 1. The metal oxide particles and silane coupling agents used at this time are as follows.

<Metal oxide particles>
A2: Hydrophobized silica particles (manufactured by Nippon Aerosil Co., Ltd .: octylsilane-treated product)
<Silane coupling agent>
B1: γ-mercaptopropyltrimethoxysilane B2: γ-mercaptopropylmethyldimethoxysilane

Evaluation of moisture resistance The prepared sample was left in an environment of 30 ° C. and 80% for 4 days, and the ratio between the initial sensitivity and the subsequent sensitivity was calculated. In this case, the closer the value is to 1, the less the deterioration of sensitivity. The values in the table are average values of 10 samples.

  The sensitivity is measured by irradiating the radiation image conversion panel with X-rays with a tube voltage of 80 KVp, and then exciting the panel with He-Ne laser light (633 nm) to excite the emitted light emitted from the phosphor layer. The measurement was performed by receiving the light with a light receiver (photoelectron image multiplier of spectral sensitivity S-5) and measuring the intensity.

  The initial sensitivity in the table is a relative sensitivity when the sensitivity when the phosphor particles are not coated with a metal oxide or surface-treated with a silane coupling agent is set to 1.

  As can be seen from the table, according to the present invention, a phosphor plate with little sensitivity deterioration due to moisture absorption can be obtained.

  The reason why the initial sensitivity tends to be improved by coating with metal oxide particles is considered to be that the metal oxide particles protect the phosphor particles from damage such as crushing, dispersion, and coating. The tendency to improve the initial sensitivity is particularly great when metal oxide particles subjected to a hydrophobic treatment are used.

  Further, the effect of preventing the deterioration of sensitivity is improved particularly when a hydrophobized metal oxide particle and a silane coupling agent having a mercapto group are used. When both are used in combination, the sensitivity is hardly deteriorated.

Comparative Example 11
To synthesize the stimulable phosphor precursor of europium activated barium, the reactor BaI2 solution (4.0mol / l) 2500ml and EuI ₃ solution (0.2mol / l) 26.5ml I put it in. The reaction mother liquor in the reactor was kept at 83 ° C. with stirring. Ammonium fluoride aqueous solution (8.0 mol / l) (322 ml) was injected into the reaction mother liquor using a roller pump to form a precipitate. After completion of the injection, the precipitate was aged by maintaining the temperature and stirring for 2 hours. Next, the precipitate was separated by filtration, washed with methanol, and then vacuum dried to obtain europium-activated barium fluoroiodide crystals.

  The obtained photostimulable phosphor precursor was filled into a quartz furnace core tube of a batch type rotary kiln having a furnace core volume of 10 liters, and 95% nitrogen / 5% hydrogen mixed gas was charged at 10 liters / min. At a flow rate of 20 minutes to replace the atmosphere. After sufficiently substituting the atmosphere in the furnace core, the flow rate of 95% nitrogen / 5% hydrogen mixed gas was 2 liters / min. 10 ° C./min. While rotating the furnace core tube at a speed of 2 rpm. It heated to 850 degreeC with the temperature increase rate of.

  After the sample temperature reached 850 ° C., a mixed gas of 93% nitrogen / 5% hydrogen / 2% oxygen was kept at 10 liters / min. At a flow rate of 20 minutes to replace the atmosphere. Thereafter, the flow rate of the mixed gas of 93% nitrogen / 5% hydrogen / 2% oxygen was set to 2 liter / min. And held for 20 minutes.

  Next, 5% hydrogen / 95% nitrogen mixed gas was supplied at 10 liters / min. At a flow rate of 20 minutes to replace the atmosphere. After sufficiently substituting the atmosphere in the furnace core, the flow rate of 95% nitrogen / 5% hydrogen mixed gas was 2 liters / min. And held for 60 minutes.

  Thereafter, the flow rate of 5% hydrogen / 95% nitrogen mixed gas was set at 2 liter / min. 10 ° C./min. After cooling to room temperature (25 ° C.) at the temperature lowering rate, the atmosphere was returned to the atmosphere, and the resulting europium-activated barium fluoroiodide phosphor particles were obtained. The resulting photostimulable phosphor particles were then classified to remove coarse particles and obtain photostimulable phosphor particles having an average particle size of 2 μm.

(Manufacture of radiation image conversion panels)
As the phosphor layer-forming material, 427 g of the europium-activated barium fluoroiodide phosphor obtained above, 15.8 g of polyurethane resin (Desmolac 4125, manufactured by Sumitomo Bayer Urethane Co., Ltd.), 2.0 g of bisphenol A type epoxy resin, methyl ethyl ketone -It added to the toluene (1: 1) mixed solvent, and it disperse | distributed with the propeller mixer, and prepared the coating liquid with a viscosity of 25-30PS. This coating solution was applied onto an undercoated polyethylene terephthalate film using a doctor blade, and then dried at 100 ° C. for 15 minutes to form a phosphor layer having a thickness of 300 μm.

(Sealing of phosphor plate)
By cutting the coated sample into a 5 cm × 5 cm square and using a laminated protective film containing an alumina-deposited PET resin layer shown in (A) below, the peripheral edge is fused using an impulse sealer under reduced pressure. Sealed.

  In addition, it fused so that the distance from a fusion | melting part to a fluorescent substance sheet peripheral part might be set to 1 mm. The impulse sealer used for the fusion was a 3 mm wide heater.

  The protective film on the support surface side of the phosphor sheet was a dry laminate film having a structure of casting polypropylene (CPP) 30 μm / aluminum film 9 μm / polyethylene terephthalate (PET) 188 μm. In this case, the thickness of the adhesive layer was 1.5 μm, and a two-component reaction type urethane adhesive was used.

VMPET in (A) indicates alumina-deposited PET (commercially available product: manufactured by Toyo Metallizing Co., Ltd.).
(A) NY15 /// VMPET12 /// VMPET12 /// PET12 /// m-CPP20
PET (polyethylene terephthalate)
NY (nylon)
CPP (casting polypropylene)

  The above “///” indicates that the thickness of the adhesive layer is 3.0 μm in the dry lamination adhesive layer, and the description of “m-” at the top of the CPP indicates that 5% by weight of silica particles are contained in the CPP resin layer. It means to include. The numbers after each resin layer indicate the film thickness (μm) of the resin layer.

(A) Example 3
After adding and dispersing the metal oxide particles and the silane coupling agent in ethanol maintained at 45 ° C., the fired stimulable phosphor obtained in the same manner as in Comparative Example 11 was immersed in the dispersion, Stir well, let stand for 5 hours, and filter. The resulting phosphor particles are dried at 80 ° C. for 12 hours, further heat treated at 120 ° C. for 3 hours, classified, and photostimulable fluorescence having an average particle diameter of 2 μm. Body particles were obtained.

The sealed phosphor plate was prepared in the same manner as in Comparative Example 11 below. The amount of ethanol used was 75% by weight with respect to the amount of phosphor, and the types of metal oxide particles and silane coupling agent and the amount added to the phosphor were as follows.
(Metal oxide particles)
A0: Hydrophobized silica (manufactured by Nippon Aerosil Co., Ltd .: dimethyldichlorosilane treated product) particle size 7 nm 1% by weight
(Silane coupling agent)
B1: γ-mercaptopropyltrimethoxysilane (manufactured by Toray Dow Corning)
1% by weight

(B) Example 4
In Example 3, a sealed phosphor plate was prepared in the same manner except that ethanol was changed to isopropanol and the silane coupling agent was changed to metal alkoxide. In addition, the kind of metal alkoxide used and the addition amount with respect to fluorescent substance are as follows.
(Metal alkoxide)
C1: Aluminum isoproxide (reagent manufactured by Kanto Chemical Co.) 1% by weight

(C) Example 5
The sealed phosphor plate was prepared in the same manner as in Example 3 except that the first metal oxide particles were added to the phosphor precursor particles and sufficiently stirred with a mixer to uniformly adhere the metal oxide particles. Created. In addition, the kind of the 1st metal oxide particle used and the addition amount with respect to fluorescent substance are as follows.
(First metal oxide particles)
A1: Alumina particles (manufactured by Nippon Aerosil Co., Ltd.) Particle size 13 nm 0.1% by weight

(D) Example 6
The first metal oxide particles are added to the phosphor precursor particles obtained in the same manner as in Comparative Example 11, and the mixture is sufficiently stirred to uniformly adhere the metal oxide particles, followed by firing in the same manner. The phosphor particles were obtained.

Further, after adding a silane coupling agent and dispersing in ethanol maintained at 45 ° C., the above phosphor particles were immersed in the dispersion, sufficiently stirred, and allowed to stand for 5 hours. After drying at 120 ° C. for 12 hours and further heat treatment at 120 ° C. for 3 hours, classification was performed to obtain photostimulable phosphor particles having an average particle diameter of 2 μm. The sealed phosphor plate was prepared in the same manner as in the comparative example below. The amount of ethanol used was 75% by weight with respect to the amount of the phosphor, and the types of the first metal oxide particles and the silane coupling agent and the amount added to the phosphor were as follows.
(First metal oxide particles)
A1: Alumina particles (manufactured by Nippon Aerosil Co., Ltd.) Particle size 13 nm 1.0% by weight
(Silane coupling agent)
B1: γ-mercaptopropyltrimethoxysilane (manufactured by Toray Dow Corning)
1% by weight

(E) Example 7
The sealed phosphor plate was prepared in the same manner as in Example 4 except that the first metal oxide particles were added to the phosphor precursor particles and sufficiently stirred with a mixer to uniformly deposit the metal oxide particles. Created. In addition, the kind of the 1st metal oxide particle used and the addition amount with respect to fluorescent substance are as follows.
(First metal oxide particles)
A1: Alumina particles (manufactured by Nippon Aerosil Co., Ltd.) Particle size 13 nm 0.1% by weight

<Evaluation of moisture resistance>
The prepared sample was left in an environment of 40 ° C. and 95% for 3 months, and the ratio between the initial sensitivity and the subsequent sensitivity was calculated. The results are shown in Table 3. In this case, the closer the value is to 1, the less the deterioration of sensitivity. The values in Table 3 are average values of 10 samples.

  The sensitivity is measured by irradiating the radiation image conversion panel with X-rays with a tube voltage of 80 KVp, and then exciting the panel with He-Ne laser light (633 nm) to excite the emitted light emitted from the phosphor layer. The measurement was performed by receiving the light with a light receiver (photoelectron image multiplier of spectral sensitivity S-5) and measuring the intensity. The initial sensitivity in Table 3 is the relative sensitivity when the sensitivity of Comparative Example 11 is 1.

Claims (13)

In the manufacturing method of a photostimulable phosphor, the manufacturing method of the photostimulable phosphor characterized by having the following process.
(A) producing a stimulable phosphor precursor;
(B) firing the precursor in the presence of a first metal oxide; and (C) coating the fired precursor with a silane coupling agent. The method for producing a stimulable phosphor according to claim 1, wherein the silane coupling agent has a mercapto group. The method for producing a photostimulable phosphor according to claim 1, wherein the silane coupling agent has a vinyl group. 3. The manufacturing method according to claim 1, wherein the step (C) is a step of coating the stimulable phosphor with a silane coupling agent of 0.1 wt% or more and 5 wt% or less. A method for producing a photostimulable phosphor. The method for producing a photostimulable phosphor according to any one of claims 1 to 4, wherein the metal oxide is hydrophobized. The method for producing a photostimulable phosphor according to any one of claims 1 to 5, wherein the metal oxide is at least one selected from silica, alumina, and titanium oxide. The manufacturing method according to claim 1, wherein the step (C) is a step of coating the calcined precursor with a silane coupling agent and a second metal oxide. A method for producing a stimulable phosphor. The manufacturing method according to claim 1, wherein the metal oxide in the step (B) is alumina, and the second metal oxide in the step (C) is silica. A method for producing a photostimulable phosphor. 9. The manufacturing method according to claim 1, wherein the photostimulable phosphor has at least a Ba atom, an F atom, an X atom, and an Ln atom (where X is F, Cl, Br, I, or N). , At, Yb and No, and Ln is at least one of Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er and Yb. And a method for producing a photostimulable phosphor. 9. The method for producing a stimulable phosphor according to claim 1, wherein the stimulable phosphor is represented by the following general formula (I).
Formula (I)
(Ba _1-x M ¹ ) FX: _y M ² , _z L _n
(However, M ¹ : at least one alkaline earth metal selected from the group consisting of Mg, Ca, Sr, Zn and Cd M ² : at least one alkali selected from the group consisting of Li, Na, K, Rb and Cs Metal X: at least one halogen selected from the group consisting of Cl, Br and I Ln: at least selected from the group consisting of Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er and Yb One kind of rare earth elements x, y, and z are 0 ≦ x ≦ 0.6, 0 ≦ y ≦ 0.05, and 0 ≦ z ≦ 0.2, respectively.
Represents each. ) A photostimulable phosphor obtained by the production method according to claim 1. A radiation image conversion panel having a phosphor layer containing a stimulable phosphor, comprising the stimulable phosphor according to claim 11. Generating a stimulable phosphor precursor; firing the precursor in the presence of a metal oxide; coating the fired precursor with a silane coupling agent; And a step of producing a phosphor layer containing the photostimulable phosphor. A method for producing a radiation image conversion panel, comprising: