JP2005113011A - Method for producing stimulable phosphor, stimulable phosphor and radiological image-converting panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing stimulable phosphor hardly causing reduction of the properties by humidity, and capable of being used in a good condition for a long period; and to provide the stimulable phosphor and a radiological image converting panel including the stimulable phosphor. <P>SOLUTION: The method for producing the stimulable phosphor involves producing the stimulable phosphor by the following steps: (A) a step for forming the stimulable phosphor; (B) a step for covering the stimulable phosphor with a silane coupling agent; and (C) a step for covering the covered stimulable phosphor with a compound containing fluorine. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a stimulable phosphor (hereinafter also simply referred to as a phosphor), a stimulable phosphor obtained by the production method, and a radiation image (also referred to as a radiation image) conversion panel having the same. More specifically, the present invention relates to a method for producing a photostimulable phosphor that can be used in a good condition without degradation in performance due to moisture absorption for a long period of time, a photostimulable phosphor, and a radiation image conversion panel.

  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-rays that have passed through the subject are irradiated onto the phosphor layer (phosphor screen), thereby generating visible light, which is the same as when taking a normal photograph in the form of 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, the 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 photostimulable phosphor, and applies radiation transmitted through the subject to the photostimulable phosphor layer of this radiation image conversion panel to cope with the radiation 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 released 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 radiographic image recording / reproducing method, a radiographic image with abundant 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.

(1) (Ba _1-X , M ²⁺ _X ) FX: yA described in JP-A-55-12145 (where M ²⁺ is at least one of Mg, Ca, Sr, Zn and Cd) 1, X is at least one of Cl, Br, and I, A is at least one of Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb, and Er, and x is A rare earth element-activated alkaline earth metal fluoride halide phosphor represented by a composition formula: 0 ≦ x ≦ 0.6, y is 0 ≦ y ≦ 0.2;
The phosphor may contain the following additives:
X ′, BeX ″, M ³ X ″ ′ ₃ described in JP-A-56-74175 (where X ′, X ″, and X ″ ′ are at least one of Cl, Br, and I, respectively) And M ³ 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 Metal oxides such as ZrO ₂ , GeO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ and ThO ₂ ;
Zr, Sc described in JP-A-56-116777;
B described in JP-A-57-23673;
As and Si described in JP-A-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 is there);
A calcined product of a tetrafluoroboric acid compound described in JP-A-59-27980;
A monovalent or divalent metal salt composition of hexafluorosilicic acid, hexafluorotitanic acid and hexafluorozirconic acid described in JP-A-59-27289;
NaX ′ described in JP-A-59-56479 (where X ′ is at least one of Cl, Br and I);
Transition metals such as V, Cr, Mn, Fe, Co and Ni described in JP-A-59-56480;
M ¹ X ′, M ′ ² X ″, M ³ X ″ ″, A described in JP-A-59-75200, where M ¹ is a group consisting of Li, Na, K, Rb, and Cs is more least one alkali metal selected, M ^'2 is at least located at one trivalent metal selected from the group consisting of be and Mg; selected from the group consisting of M ³ represents Al, Ga, in, and Tl At least one trivalent metal; A is a metal oxide; X ′, X ″ and X ″ ′ are at least one halogen selected from the group consisting of F, Cl, Br and I, respectively);
M ¹ X ′ described in JP-A-60-101173 (where M ¹ is 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:
M ² ′ X ′ ₂ .M ² ′ X ″ ₂ described in JP-A 61-23679 (where M ² ′ is at least one alkaline earth metal selected from the group consisting of BaSr 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 described in Japanese Patent Application No. 60-106752. LnX ″ ₃ (wherein Ln is at least one selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, 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 alkali 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); a divalent europium-activated alkaline earth metal halide phosphor represented by a composition formula:
The phosphor may contain the following additives: M ¹ X ″ described in JP-A-60-166379 (where M ¹ is a group consisting of Rb and Cs) At least one alkali metal selected from X; and X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I);
KX ″, MgX ″ ′ ₂ , M ³ X ″ ″ ₃ described in JP-A-60-222143 (where M ³ is at least one selected from the group consisting of Sc, Y, La, Gd and Lu) 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 ″ and 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 halogen selected from the group consisting of F, Cl, Br and I, respectively) And CsX ″, Ln ³⁺ described in JP-A-61-223587 (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 at least one rare earth element selected from the group consisting of Lu);
(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 0 <x <0.1). The rare earth element activated rare earth oxyhalide phosphor represented by the composition formula:
(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 alkali selected from the group consisting of Ca, Sr and Ba) X is an 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. Divalent 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) 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) 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 each selected from the group consisting of Y, La, Gd and Lu) At least one rare earth element; 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 number in a range of a ≦ 10.0, and x is a numerical value in a 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 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 each selected from the group consisting of Cl, Br and I And at least one halogen; and a is a numerical value in a range of 0 <a ≦ 10.0, and x is a numerical value in a range of 0 <x ≦ 0.2). Halide phosphors;
(12) LnPO ₄ · aLnX ₃ : xCe ³⁺ described in JP-A No. 61-40390 (wherein 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. 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). (14) M ² X ₂ · aM ¹ X ′: xEu ²⁺ described in Japanese Patent Application No. 60-78153 (where M ² is selected from the group consisting of Ba, Sr and Ca) at least be a one alkaline earth metal; M ¹ is Li, it is at least one alkali metal selected from the group consisting of Rb and Cs; X and X 'each is Cl, Br and I Tona At least one halogen selected from the group; 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). And the divalent europium activated composite halide phosphors represented.

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

  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.

A method of reducing moisture reaching the phosphor layer by coating the stimulable phosphor layer with a moisture-proof protective layer or a moisture-proof resin film having a low moisture permeability, and the above-described deterioration due to moisture absorption of the stimulable phosphor particles In order to prevent the phenomenon, a titanate coupling agent method (see, for example, Patent Document 1) and a silicone oil method have been proposed (see, for example, Patent Document 2). It has not yet been resolved.
Japanese Patent Publication No. 2-278196 Japanese Patent Publication No. 5-52919

  An object of the present invention is to provide a method for producing a photostimulable phosphor that can be used in a good condition for a long time without performance deterioration due to moisture absorption, a photostimulable phosphor, and a radiation image conversion panel having the same. is there.

  The above object of the present invention is achieved by the following configurations.

1. A method for producing a photostimulable phosphor, comprising producing a photostimulable phosphor through the following process sequence.
(A) Step of generating stimulable phosphor (B) Step of coating the stimulable phosphor with a silane coupling agent (C) Covering the coated stimulable phosphor with a compound containing fluorine Step 2. 2. The method for producing a photostimulable phosphor according to 1 above, wherein the photostimulable phosphor is a compound represented by the following general formula (1).

General formula (1)
(Ba _1-x M ² _x ) FBryI _1-y X: aM ¹ , bLn, cO
Wherein M ¹ is at least one alkali metal atom selected from Li, Na, K, Rb and Cs, and M ² is at least one alkaline earth metal atom selected from Mg, Ca, Sr, Zn and Cd. , X is at least one halogen atom selected from Cl, Br and I, Ln is at least one rare earth element selected from Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er and Yb X, y, a, b, and c are 0 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.3, 0 ≦ a ≦ 0.05, 0 <b ≦ 0.2, and 0 <c, respectively. ≦ 0.1)
3. A method for producing a photostimulable phosphor, characterized in that a photostimulable phosphor produced by a liquid phase method is produced through the following sequence of steps.
(A) Step of generating stimulable phosphor (B) Step of coating the stimulable phosphor with a silane coupling agent (C) Covering the coated stimulable phosphor with a compound containing fluorine Step 4. 4. The method for producing a stimulable phosphor as described in 3 above, wherein the stimulable phosphor produced by the liquid phase method is a compound represented by the general formula (1).

  5). 5. The method for producing a photostimulable phosphor according to any one of 1 to 4, wherein the fluorine-containing compound is a coating composition obtained by dissolving a fluorine-containing polymer with a fluorinated solvent.

  6). 6. The method for producing a photostimulable phosphor according to any one of 1 to 5, wherein the silane coupling agent has a mercapto group.

  7). 6. The method for producing a photostimulable phosphor according to any one of 1 to 5, wherein the silane coupling agent has a vinyl group.

  8). The fluorine concentration of the compound containing fluorine is 0.2 to 20% by mass with respect to the stimulable phosphor, and the silane coupling agent is 0.1 to 5% by mass with respect to the stimulable phosphor. The method for producing a photostimulable phosphor according to any one of 1 to 7 above.

  9. A photostimulable phosphor obtained by the method according to any one of 1 to 8 above, wherein the photostimulable phosphor represented by the general formula (1) is obtained.

  10. A radiation image conversion panel comprising the photostimulable phosphor described in 9 above.

  The method for producing a photostimulable phosphor according to the present invention, the photostimulable phosphor and a radiation image conversion panel having the photostimulable phosphor can be used in a good condition for a long time without performance deterioration due to moisture absorption, and have an excellent effect.

  As the photostimulable phosphor of the present invention, any of the photostimulable phosphors (1) to (14) described in the background art may be used, but the present inventors have absorbed moisture of the photostimulable phosphor. As a result of various studies on the phenomenon of sensitivity degradation due to luminescence, it was found that the performance degradation is caused by the deliquescent of the phosphor due to moisture absorption and the alteration of the phosphor.

  Therefore, preventing either deliquescence or alteration is not a fundamental solution. Therefore, as a result of intensive investigations to prevent both deliquescence and alteration, it has been found that the object of the present invention can be solved by producing a photostimulable phosphor through the above process steps.

  The above-mentioned deliquescence refers to a phenomenon in which photostimulable phosphor particles take water vapor in the air to create an aqueous solution by themselves, and alteration does not deliquesce, but the fluorescence characteristics of the phosphor itself change due to water vapor in the air. Say that. Although the mechanism of alteration is not clear, structural changes in the photostimulable phosphor particles can be considered.

  The fluorine-containing compound used in the present invention is effective in preventing both deliquescence and alteration, but it is effective for phosphors such as liquid preparation, dispersion, and coating in the manufacturing process of stimulable phosphor plates. There is a drawback that a compound containing fluorine is easily peeled off from the surface of the photostimulable phosphor particles in a process where an external force is applied.

  Therefore, the present inventors provided a step of coating the photostimulable phosphor of the present invention with a step of coating with a silane coupling agent, and further coating the coated photostimulable phosphor with a fluorine compound. By coating and producing the photostimulable phosphor, the silane coupling agent and the fluorine compound act firmly on the photostimulable phosphor particles, and failures due to liquid preparation, dispersion, coating, etc. are reduced, and the object of the present invention I found that I can achieve.

  In addition, it has also been found that by using a mercapto-modified silane coupling agent in the above step, this effect is strengthened and the performance change of the stimulable phosphor particles is reduced.

  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 photostimulable phosphor particles as water droplets, performance degradation occurs due to deliquescence.

  This phenomenon was particularly likely to occur with photostimulable phosphors containing halogen atoms.

  Hereinafter, these methods will be described.

  It is presumed that there is an effect of preventing the occurrence of such a deliquescence by providing a stimulable phosphor by providing a coating treatment step with a fluorine-containing compound and a silane coupling agent of the present invention. It has also been found that this effect is particularly great for stimulable phosphors containing halogen atoms.

  Although it was presumed that the treatment with a fluorine-containing compound was effective for preventing changes in the performance of the phosphor, it was difficult to form a film of the compound containing fluorine directly on the photostimulable phosphor particles.

  In the present invention, in the above two coating steps, the silane coupling agent can strongly bond the fluorine compound film and the photostimulable phosphor particles, and the effect of the present invention is obtained by the fluorine compound film. Estimated.

  As the fluorine-containing compound used in the step of coating the photostimulable phosphor of the present invention, the following compounds having fluorine are preferable.

  As the fluorine-containing polymer preferably used in the present invention, the fluoroaliphatic group-containing unsaturated ester monomer for the copolymer is a fluoroaliphatic group-containing unsaturated ester monomer that is at least partially substituted with fluorine. A compound containing an aliphatic group, particularly an alkyl group at least partially substituted with fluorine, and having a polymerizable ethylenically unsaturated carbon-carbon double bond. Specifically, examples of the fluoroaliphatic group-containing unsaturated ester monomer include the following.

Rf—Q—O—C (═O) —C (R ₁ ) ═CH ₂
Rf is a linear, branched or cyclic at least partially fluorinated aliphatic group having 2 to 12 carbon atoms, such as an at least partially fluorinated alkyl group, preferably fully fluorinated. R ₁ is a hydrogen atom or CH ₃ , Q is a lower alkylene group such as —CH ₂ —, —CH ₂ CH ₂ —, or —SO ₂ NR ₂ —lower alkylene group, — SO ₂ NR ₂ —CH ₂ —, —SO ₂ NR ₂ —CH ₂ CH ₂ —, and R ₂ is a hydrogen atom or a lower alkyl group such as —CH ₃ or —C ₂ H ₅ .

Rf is preferably a C _{3 to} C ₇ fluoroaliphatic group, particularly preferably a C _{3 to} C ₆ fluoroaliphatic group.

In addition, when the terminal group of Rf is a completely fluorinated —CF ₃ group, it is preferable in that the effect of the present invention is further exerted. Q is a lower alkyl group, preferably —CH ₂ — or —CH ₂ CH ₂ —.

More _{specifically, F (CF 2) 6 CH} 2 OC (= O) C (CH 3) = CH 2, C 7 F 15 -SO 2 N (C 2 H 5) C 2 H 4 OC (= O _{) C (CH 3) = CH} 2, c-C 6 F 11 CH 2 OC (= O) C (CH 3) = CH 2, C 6 F 13 C 2 H 4 OC (= O) CH = CH 2, (CF ₃ ) ₂ CF (CF ₂ ) ₂ C ₂ H ₄ OC (═O) CH═CH ₂ , H (CF ₂ ) ₄ CH ₂ OC (═O) CH═CH ₂ , F (CF ₂ ) ₄ C ₂ H ₄ OC (═O) CH═CH ₂ , F (CF ₂ ) ₃ CH ₂ OC (═O) CH═CH ₂ . These monomers can be prepared by conventional methods such as those described in U.S. Pat. Nos. 2,803,615 and 2,841,573.

  Also, it can be obtained by radical polymerization of a perfluoroether having two terminal double bonds alone or by radical polymerization of a perfluoroether having two terminal double bonds together with other monomers capable of radical copolymerization. A polymer is mentioned.

  Such polymers are disclosed, for example, in JP-A-63-238111 and JP-A-63-238115.

That is, perfluoroether having two double bonds at the end, for example, CF ₂ ═CF (CF ₂ ) n—O— (CF ₂ ) mCF═CF ₂ ,
(N is 0-5, m is 0-5, m + n is 1-6)
Can be radically polymerized alone, or can be cyclopolymerized by radical polymerization with a perfluoroether having two terminal double bonds and other monomers capable of radical copolymerization to obtain a fluorine-containing polymer. For example, by radical polymerization of _{CF 2 = CF-O-CF} 2 CF = CF 2, as follows in the main chain, fluorine-containing polymer having a 5-membered ring structure.

  Other monomers capable of radical copolymerization with the perfluoroether having two terminal double bonds include fluoroolefins such as tetrafluoroethylene, fluorovinyl ethers such as perfluorovinyl ether, vinylidene fluoride, and vinyl fluoride. And chlorotriethylene.

  Further, examples of the fluorine-containing polymer include those disclosed in JP-B 63-18964.

  Specifically, an amorphous copolymer having a perfluoro-2,2-dimethyl-1,3-dioxole (PDD) monomer unit and a tetrafluoroethylene monomer unit represented by the above, or the above monomer Examples thereof include an amorphous terpolymer having a monomer unit of another ethylenically unsaturated monomer as a unit.

  Examples of the ethylenically unsaturated monomer for the terpolymer include olefins such as ethylene and 1-butene, vinyl compounds such as vinyl fluoride and vinylidene fluoride, and perfluoro compounds such as perfluoropropene. Can be used.

  As commercially available fluorine-containing polymers, Cytop CTX-805 and CTX109A (trade names) manufactured by Asahi Glass Co., Ltd. are also preferably used.

Examples of the fluorine polymer solvent include ethers containing hydrogen atoms and fluorine atoms, that is, hydrofluoroether (HFE). Useful hydrofluoroethers include the following two types:
(1) The HFE ether-linked alkyl or alkylene segment is perfluorinated (eg, perfluorocarbon group) or non-fluorinated (eg, hydrocarbon group), thus Non-fluorinated, separated hydrofluoroether, and
(2) The ether-linked segment is not fluorinated (eg, a hydrocarbon group), perfluorinated (eg, a perfluorocarbon ether group), or partially fluorinated (eg, a fluorocarbon) Or hydrofluorocarbon group), ω-hydrofluoroalkyl ether.

  The separated hydrofluorocarbon ether is a mono-, di- or trialkoxy-substituted perfluoroalkane, perfluorocycloalkane, perfluorocycloalkyl-containing perfluoroalkane 1 or perfluorocycloalkylene-containing perfluoroalkane compound. Includes hydrofluoroethers including species. These HFEs are described in, for example, the specification of WO96 / 22356, and a compound represented by the following formula 1 is preferable.

Formula 1: Rf- (O-Rh) x
In Formula 1, x is 1 to 3, preferably 1, and Rf is a perfluorinated linear, branched or cyclic hydrocarbon group having a valence of x, and the carbon number thereof is 6 is to 15, Rf may contain a hetero atom present in one or more chains, and Rf in all cases may contain F ₅ S- group at the end, each Rh is independently 1-3 It is a straight chain or branched alkyl group having 1 carbon atom, preferably 1 or 2 carbon atoms, and more preferably a methyl group. Among the above HFEs, those in which Rf does not contain a heteroatom and does not contain an F ₅ S-group at the terminal are preferred.

  Examples of typical hydrofluoroether compounds represented by Formula 1 include the following compound examples.

  In the above compounds, the ring structure described as “F” is perfluorinated. These HFE compounds may be used alone or as a mixture with another HFE.

  As other useful hydrofluoroethers, ω-hydrofluoroalkyl ethers having a general structure represented by the following formula 2 can also be preferably used.

Formula 2: X—Rf ′ — (O—Rf ″) y—O—R ″ —H
In the above compounds, X is a fluorine atom or a hydrogen atom, Rf ′ is a divalent perfluorinated organic group having 1 to 12 carbon atoms, and Rf ″ has 1 to 6 carbon atoms. A divalent, perfluorinated organic group, R ″ is a divalent organic group having 1 to 6 carbon atoms, and is preferably perfluorinated, y is an integer from 0 to 4 , X is a fluorine atom and y is 0, R ″ contains at least one F atom, provided that the total number of fluorinated carbon atoms is at least 6.

  The typical compound example of the compound represented by Formula 2 is given below.

C ₄ F ₉ OC ₂ F ₄ H
HC ₃ F ₆ OC ₃ F ₆ H
C ₅ F ₁₁ OC ₂ F ₄ H
C ₆ F ₁₃ OCF ₂ H
C ₆ F ₁₃ OC ₂ HF _{4
c-C 6 F 11 CF 2} OC 2 F 4 H
HCF ₂ O (C ₂ F ₄ O) n (CF ₂ O) CF ₂ H
C ₃ F ₇ O {C (CF ₃ ) CF ₂ O} pCFHCF ₃
C ₄ F ₈ OCF ₂ C (CF ₃ ) ₂ CF ₂ H
HCF ₂ CF ₂ OCF ₂ C (CF ₃ ) ₂ CF ₂ OC ₂ F ₄ H
C ₇ F ₁₇ OCHFHC ₃
C ₈ F ₁₀ OCF ₂ O (CF ₂ ) ₅ H
C ₈ F ₁₀ OC ₂ F ₄ OC ₂ F ₄ OCF ₂ H
Particularly useful solvents in the coating composition and coating method of the present _{invention, Rf "'- OC 2 H} 5 (Rf"' is a page fluoroalkyl group having 6 to 15 carbon atoms linear or branched) Have Preferably, Rf ″ ′ has 6 to 8 carbon atoms and 3-ethoxyperfluoro (2-methylhexane) (CF ₃ CF (CF ₃ ) CF (OC ₂ H ₅ ) C ₃ F ₇ ) Most preferred.

These solvents have the same solvent characteristics as conventional PFC solvents. Specifically, 3-ethoxy-perfluoro (2-methyl hexane), the surface tension and viscosity as a factor to determine the ability to form a uniform and thin coating (25 ° C.), respectively, 1.4 × 10 ^{- 2} N / m and 1.2 × 10 ⁻³ Pa · s, and high solubility equivalent to PFC in fluorine-containing polymers.

  The coating composition is easily formed by adding the above polymer having a fluorine-containing ring structure to hydrofluoroether (HFE) at room temperature (for example, 25 ° C.) and stirring.

  The solution concentration of the fluorine-containing polymer composition is usually 1 to 20% by mass although it depends on the type of the fluorine-containing polymer.

HFE (for example, CF ₃ CF (CF ₃ ) CF (OC ₂ H ₅ ) C ₃ having excellent solvent properties for dissolving the fluorine-containing compound in the step of coating the stimulable phosphor with the fluorine-containing compound of the present invention. F ₇ ) When used, a uniform surface (coating) treatment can be performed even in a thin surface (coating) treatment. According to the study by the present inventors, the fluorine-containing compound has an effect of preventing discoloration of the stimulable phosphor, and the above-mentioned particularly preferable fluorine-containing compound reduces the sensitivity due to the coloring of the phosphor in addition to the moisture-proof effect. The effect to prevent is also added. The effect of preventing discoloration is remarkable when the phosphor contains iodine in the structure, and effectively prevents yellowing of the phosphor due to free iodine.

  The silane coupling agent used in the step of coating the photostimulable phosphor of the present invention will be described.

  Although there is no restriction | limiting in particular as a silane coupling agent which can be used by this invention, The compound represented with the following general formula (I) is preferable.

In the general formula (I), R represents an aliphatic or aromatic hydrocarbon group, which may have an unsaturated group (for example, vinyl group) interposed therebetween, or R ₂ OR ₃ —, R ₂ COOR ₃ —. , R ₂ NHR ₃ — (R ₂ represents an alkyl group or an aryl group, R ₃ represents an alkylene group or an arylene group), and may be substituted with other substituents.

X ₁ , X ₂ and X ₃ each represents an aliphatic or aromatic hydrocarbon, acyl group, amide group, alkoxy group, alkylcarbonyloxy group, epoxy group, mercapto group or halogen atom. However, at least one of X ₁ , X ₂ , and X ₃ is a group other than hydrocarbon. X ₁ , X ₂ and X ₃ are each preferably a group that undergoes hydrolysis.

  Specific examples of the silane coupling agent represented by the general formula (I) include, for example, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, γ-chloropropyltri Methoxysilane, γ-chloropropylmethyldichlorosilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltri Methoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycid Cypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ- (2 -Aminoethyl) aminopropylmethyldimethoxysilane, γ-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride and aminosilane In particular, vinyl-based, mercapto-based, glycidoxy-based, and methacryloxy-based are preferable. In particular, the invention of claim 3 is characterized in that the silane coupling agent has a mercapto group.

  As a method for coating the photostimulable phosphor particles with the fluorine-containing compound and the silane coupling agent, a known method can be used. For example, a dry method in which a compound having fluorine and a silane coupling agent are dropped or sprayed while stirring and mixing the stimulable phosphor particles, a compound having fluorine in a slurry phosphor, and a silane coupling agent A slurry method in which the phosphor is precipitated and filtered after the dropping is completed, and the phosphor is dried to remove the residual solvent. The phosphor is dispersed in the solvent, and the fluorine-containing compound and the silane coupling agent There is a method of evaporating the solvent and then stirring to form an adhesion layer by evaporating the solvent, or a method of adding a fluorine-containing compound and a silane coupling agent to the stimulable phosphor coating dispersion. Further, it is desirable to dry the fluorine-containing compound and the silane coupling agent at 60 to 130 ° C. for about 10 to 200 minutes in order to ensure the reaction with the phosphor.

  As an example of the method of coating in the coating step of such photostimulable phosphor particles, for example, the photostimulable phosphor particles immediately after firing are disintegrated in a liquid, and the photostimulable phosphor particles are coated. Examples include a method of performing filtration and drying, and a method in which a fluorine-containing compound and a silane coupling agent are added to the coating dispersion liquid for stimulable phosphor layer and coating is performed, but the present invention is limited to these. is not.

  In the present invention, when the amount of the fluorine-containing compound exceeds 20% with respect to the phosphor, the sensitivity decreases, and when it is less than 0.2%, the effect of the present invention is halved.

  On the other hand, when the amount of the silane coupling agent exceeds 20% 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 less than 0.2%, the effect of the present invention is halved.

  When the photostimulable phosphor (particles) of the present invention is coated with a silane coupling agent, and then the photostimulable phosphor (particles) is coated with a fluorine-containing compound, the photostimulant exhibits good moisture resistance. Phosphor particles can be obtained, and the effect of improving the moisture resistance of the particles can be obtained even if the phosphor particles are applied as a phosphor layer on the support through the dispersion, liquid preparation and coating steps.

  When a step of coating the photostimulable phosphor particles with a silane coupling agent and a step of coating the photostimulable phosphor particles with a compound containing fluorine are provided, the photostimulable fluorescence is dispersed, prepared, and applied. It is not certain that the fluorine-containing compound will not peel off from the body particles, but it is presumed that some bonding occurs between the photostimulable phosphor particles and the fluorine-containing compound.

  Therefore, in the present invention, when the total amount of the silane coupling agent is 20% or less with respect to the phosphor, a decrease in sensitivity can be reduced, and when it is 0.2% or more, the effect of the present invention is further achieved. preferable.

  The photostimulable phosphor represented by the general formula (1) that is particularly preferably used in the present invention will be described.

In the general formula (1), M ¹ is at least one alkali metal atom selected from Li, Na, K, Rb, and Cs, and M ² is at least one alkali selected from Mg, Ca, Sr, Zn, and Cd. Earth metal atom, X is at least one halogen atom selected from Cl, Br and I, Ln is at least selected from Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er and Yb It is a kind of rare earth element. x, y, a, b, and c are 0 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.3, 0 ≦ a ≦ 0.05, 0 <b ≦ 0.2, 0 <c ≦ 0. 1.

  The shape of the particles in the photostimulable phosphor of the present invention may be any shape such as plate-like particles, spherical particles, hexahedral particles, and tetrahedral particles.

  In the present invention, a stimulable phosphor precursor produced by a liquid phase synthesis method can be preferably used. In the liquid phase synthesis method, the shape and particle size of the photostimulable phosphor precursor can be controlled relatively easily by controlling the degree of supersaturation of the reaction solution system. For example, JP-A-7-233369 discloses a tetrahedral photostimulable phosphor by a liquid phase method and a method for producing the same. The tabular grains having a high aspect ratio in the present invention are also preferably produced using a liquid phase synthesis method.

  For the production of the photostimulable phosphor precursor by the liquid phase method, the precursor production method described in Japanese Patent Application No. 8-265525 and the precursor production apparatus described in Japanese Patent Application No. 8-266718 can be preferably used.

  In the present invention, the photostimulable phosphor precursor means a state in which the substance of the general formula (I) has not passed through a high temperature of 600 ° C. or higher (not baked), and the photostimulable phosphor precursor is a photostimulable phosphor precursor. It shows almost no light emission or instantaneous light emission.

  In the present invention, it is preferable to obtain a stimulable phosphor precursor by the following liquid phase synthesis method.

(Precursor production method)
In the case where a halide of BaI ₂ and Ln is included and a in the general formula (I) is not 0, a halide of M1 is further included, and after they are dissolved, the BaI ₂ concentration is 1.6 mol / L or more, preferably Is a step of preparing an aqueous solution having a concentration of 3.5 mol / L or higher; while maintaining the aqueous solution at a temperature of 50 ° C. or higher, preferably 80 ° C. or higher, an inorganic fluoride having a concentration of 6 mol / L or higher, preferably 8 mol / L or higher. Adding an aqueous solution of fluoride (ammonium fluoride or alkali metal fluoride) to obtain a precipitate of stimulable phosphor precursor crystals; and separating the precursor crystal precipitate from the aqueous solution. It is a waste.

  The photostimulable phosphor precursor exhibits a photostimulable luminescent property and an instantaneous luminescent property for the first time through a firing step. The production of the photostimulable phosphor from the phosphor precursor is preferably performed by a firing method as described below.

(Baking method)
Heating the photostimulable phosphor precursor to 600 ° C. or higher while exposing it to a weakly reducing atmosphere containing no more than 100 ppm of oxygen;
After the step, introducing oxygen in the atmosphere at a volume ratio of at least 100 ppm and at most less than the volume ratio of the reducing component to the whole atmosphere while maintaining at 600 ° C. or higher, and holding it for at least 1 minute;
And after the said process, after hold | maintaining 600 degreeC or more, returning atmosphere to 1000 ppm or more (preferably 100 ppm or more) weakly reducing atmosphere which does not contain oxygen, and holding for at least 30 minutes, 1000 ppm or more (preferably 100 ppm or more) This is a step of cooling to 100 ° C. or lower while maintaining a weakly reducing atmosphere containing no oxygen.

  Details of the method for producing the photostimulable phosphor of the present invention will be described below.

(Preparation of precursor crystal precipitates)
First, raw material compounds other than fluorine compounds are dissolved in an aqueous medium. That is, BaX ₂ (BaBr ₂ , BaI ₂ ) and a halide of Ln, and if necessary, further a halide of M2, and further a halide of M1 are placed in an aqueous medium, mixed well and dissolved, A dissolved aqueous solution is prepared. However, the amount ratio between the BaX ₂ (BaBr ₂ , BaI ₂ ) concentration and the aqueous solvent is adjusted so that the BaX ₂ (BaBr ₂ , BaI ₂ ) concentration is 0.25 mol / L or more. At this time, if desired, a small amount of acid, inorganic halide (ammonium salt, potassium salt, sodium salt, etc.), ammonia, alcohol, water-soluble polymer, water-insoluble metal oxide fine particle powder and the like may be added. This aqueous solution (reaction mother liquor) is maintained at 50 ° C. or higher.

  Next, an aqueous solution of inorganic fluoride (ammonium fluoride, alkali metal fluoride, etc.) is injected into the aqueous solution maintained at 50 ° C. or higher and stirred using a pipe with a pump or the like. This injection is preferably performed in a region where stirring is particularly intense. By injecting the inorganic fluoride aqueous solution into the reaction mother liquor, the phosphor precursor crystal corresponding to the general formula (I) is precipitated.

  Next, the precursor crystals are separated from the solution by filtration, centrifugation, etc., sufficiently washed with methanol or the like, and dried. A sintering inhibitor such as alumina fine powder or silica fine powder is added to and mixed with the dried phosphor precursor crystal, and the fine powder of sintering inhibitor is uniformly attached to the crystal surface. It is possible to omit the addition of the sintering inhibitor by selecting the firing conditions.

(Baking of precursor crystals)
The phosphor precursor crystal powder is filled in a heat-resistant container such as a quartz port, an alumina crucible, a quartz crucible, etc., and placed in the core of an electric furnace and fired while avoiding sintering. However, the core of the electric furnace is limited to one that can replace the atmosphere during firing. As the electric furnace, a moving bed type electric furnace such as a rotary kiln can be preferably used.

  After filling the furnace core with the phosphor precursor, the atmosphere in the furnace core is replaced from the atmosphere with a weakly reducing atmosphere containing no more than 1000 ppm (preferably 100 ppm or more) oxygen. The weakly reducing atmosphere is preferably a hydrogen / nitrogen mixed gas having a hydrogen concentration of 5% or less, more preferably a hydrogen concentration of 0.1 to 3%. When the hydrogen concentration is 0.1% or more, reducing power can be obtained and the light emission characteristics can be improved. On the other hand, when the hydrogen concentration is 5% or less, it is preferable in handling, and the crystal of the stimulable phosphor itself is It can prevent being reduced.

  Prior to this atmosphere replacement, the atmosphere inside the furnace core may be discharged and evacuated. A rotary pump or the like can be used for vacuum suction. When the furnace core is evacuated, there is an advantage that the replacement efficiency of the atmosphere is increased. In the case of so-called purge replacement in which the atmosphere is replaced without going through a vacuum, it is necessary to inject an atmosphere having a volume at least three times the capacity of the furnace core.

  After replacing the inside of the core of the electric furnace with the above mixed atmosphere, heating is performed to 600 ° C. or higher. As described above, it is preferable to heat to 600 ° C. or higher because good light emission characteristics can be obtained. It is preferable that the mixed atmosphere in the furnace core is circulated at a flow rate of at least 0.1 L / min from the start of heating to the extraction of the photostimulable phosphor.

  Thereby, since the atmosphere in a furnace core is substituted, reaction products other than the stimulable phosphor produced | generated in a furnace core can be discharged | emitted.

  In particular, since the reaction product of the present invention contains iodine, it is possible to prevent yellowing of the photostimulable phosphor due to iodine and accompanying degradation of the photostimulable phosphor.

  More preferably, the flow rate is 1.0 to 5.0 L / min. The rate of temperature rise is preferably 1 to 50 ° C./min, although it varies depending on the material of the furnace core, the amount of precursor crystals filled, the specifications of the electric furnace, and the like.

  After reaching 600 ° C. or higher, oxygen having a volume ratio smaller than the volume ratio of the reducing component to the entire atmosphere is introduced into the atmosphere and held for at least 1 minute. The temperature at this time is preferably 600 to 1300 ° C, more preferably 700 to 1000 ° C. When the temperature is set to 600 ° C. or higher, good photostimulated luminescence characteristics can be obtained, and when the temperature is 700 ° C. or higher, more preferable photostimulated luminescence properties for practical diagnosis of radiographic images can be obtained. Moreover, if it is 1300 degrees C or less, it can prevent that it enlarges by a sintering, and if it is 1000 degrees C or less especially, the stimulable fluorescent substance of the particle diameter which is practically preferable for the diagnosis of a radiographic image can be obtained. it can. More preferably, it is around 820 ° C.

  Here, the replacement of the atmosphere is performed by purge replacement, and the newly introduced weakly reducing atmosphere is preferably a mixed gas in which the hydrogen concentration is 5% or less, the oxygen concentration is less than the hydrogen concentration, and the remaining components are nitrogen. More preferably, it is a mixed gas in which the hydrogen concentration is 0.1 to 3%, the oxygen concentration is 40 to 80% with respect to the hydrogen concentration, and the remaining component is nitrogen. In particular, a mixed gas containing 1% hydrogen, 0.6% oxygen, and nitrogen as the remaining components is preferable.

  When the hydrogen concentration is 0.1% or more, reducing power can be obtained, and the light emission characteristics can be improved. When the hydrogen concentration is 5% or less, it is preferable for handling, and the photostimulable phosphor crystal itself is further reduced. Can be prevented. Further, the stimulated emission intensity can be remarkably improved with the oxygen concentration peaking at about 60% with respect to the hydrogen concentration.

  In addition, oxygen may be mixed into the atmosphere being heated. In this case, the mixing ratio of the atmosphere can be controlled by manipulating the flow ratio of the hydrogen / nitrogen mixed gas and the oxygen gas. In addition, air can be introduced as it is as an alternative to oxygen. Further, the flow rate ratio of the oxygen / nitrogen mixed gas and the hydrogen / nitrogen mixed gas can be adjusted for use.

  Until the desired mixing ratio of nitrogen, hydrogen, and oxygen is replaced, it is necessary to introduce a new atmosphere having a volume that is at least three times the capacity of the furnace core. From this time, a mixed atmosphere of nitrogen, hydrogen, and oxygen is maintained at 600 ° C. or higher for at least 1 minute or longer, preferably 1 minute to 1 hour.

  By the above firing, the target oxygen-introduced rare earth activated alkaline earth metal fluoride halide photostimulable phosphor is obtained.

(Coating treatment with silane coupling agent) (Surface treatment)
As a method for performing the surface treatment with the silane coupling agent on the surface of the phosphor particles, a known method can be used. For example, using a Henschel 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 a solvent, a silane coupling agent is added thereto and stirred, and then 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. As an example of such a processing method, phosphor particles immediately after firing in a dispersion of fine particles and a silane coupling agent are crushed in the liquid, and simultaneously with the pulverization of the phosphor, coating with hydrophilic fine particles and silane Examples include a method of performing filtration treatment after surface treatment with a coupling agent and a method of adding hydrophilic fine particles and a silane coupling agent to a coating dispersion for a stimulable phosphor layer. It is not limited.

(Coating treatment with fluorine-containing compound) (Surface treatment)
A compound containing fluorine has an effect of preventing discoloration of the stimulable phosphor, and also has an effect of preventing deterioration of sensitivity due to coloring of the stimulable phosphor.

  Although the reason is not clear, the prevention of discoloration of the photostimulable phosphor of the compound containing fluorine is remarkable when the phosphor contains iodine, and it can prevent yellowing of the phosphor by free iodine. Estimated.

  A known method can be used to adhere the phosphor particles to the coating agent obtained by dissolving the above-mentioned fluoropolymer with a fluorinated solvent.

  For example, while stirring and mixing phosphor particles using a Henschel mixer, a coating agent containing a fluorine polymer is picked and sprayed, while a slurry containing a fluorine polymer is picked up from a slurry phosphor. Stirring, and after completion of picking, the phosphor is precipitated and filtered, and then the phosphor is dried to remove the residual solvent. Disperse the phosphor in the solvent, and add the fluoropolymer-containing coating agent to it. Then, after stirring, the surface treatment can be performed by evaporating the solvent or adding a fluoropolymer-containing coating agent to the stimulable phosphor coating dispersion and stirring.

  In order to ensure the reaction with the fluorescent substance, the fluorine polymer-containing coating agent is preferably subjected to a surface treatment at a temperature of 40 to 160 ° C. for 10 to 200 minutes.

  As an example of such a surface treatment method of phosphor particles, phosphor particles immediately after firing in a dispersion of a fluorine polymer-containing coating agent are pulverized in the liquid, and the surface treatment is performed with the fluorine polymer-containing coating agent. Then, the surface treatment of the photostimulable phosphor particles with a silane coupling agent was performed with a Henschel mixer on the coating dispersion of the photostimulable phosphor with a fluoropolymer-containing coating agent.

(Production of radiation image conversion panel)
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. From this viewpoint, plastics such as cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, and polycarbonate are preferable. 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 preferred.

  Although the layer thickness of these supports varies depending on the material of the support used, it is generally 80 to 1000 μm, and more preferably 80 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 stimulable phosphor layer. Furthermore, you may provide an undercoat layer in the surface in which a photostimulable phosphor layer is provided in order to improve adhesiveness with a photostimulable phosphor layer.

  Examples of binders used in the photostimulable phosphor layer include proteins such as gelatin, polysaccharides such as dextran, or natural polymer materials such as gum arabic; polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, Binders represented by synthetic polymer materials such as 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 these are nitrocellulose, linear polyester, polyalkyl (meth) acrylate, a mixture of nitrocellulose and linear polyester, a mixture of nitrocellulose and polyalkyl (meth) acrylate, and polyurethane and polyvinyl butyral. And a mixture. 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, in order to prevent yellowing of the iodine-containing photostimulable phosphor of the present invention, a compound such as a phosphite and a binder are added to a suitable solvent, and these are mixed well to produce a phosphor in the binder solution. A coating liquid in which the fluorescent particles and the compound particles are uniformly dispersed is prepared.

  Generally, a binder is used in 0.01-1 mass part with respect to 1 mass part of stimulable fluorescent substance. 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 mass is more preferable from the viewpoint of easy application.

  The mixing ratio of the binder to the stimulable phosphor in the coating solution (however, when the entire binder is an epoxy group-containing compound, it is equal to the ratio of the compound to the phosphor) is the intended radiographic image. Although it depends on the characteristics of the conversion panel, the type of phosphor, the amount of the epoxy group-containing compound added, etc., in general, as examples of solvents for preparing the bonding coating solution, methanol, enotal, 1-propanol, 2-propanol, butanol, etc. Lower alcohols; Chlorine atom-containing hydrocarbons such as methylene chloride and ethylene chloride; 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; Dioxane, ethylene glycol Such as ethyl ether, ethylene glycol monomethyl ether, etc. Ether; toluene; and it can include mixtures thereof.

  The coating solution may be mixed with a dispersant such as stearic acid, phthalic acid, caproic acid, a lipophilic surfactant for the purpose of improving the dispersibility of the stimulable phosphor particles in the coating solution. Good. Moreover, you may add the plasticizer with respect to a binder as needed. Examples of such plasticizers include: phthalates such as diethyl phthalate and dibutyl phthalate; aliphatic dibasic esters such as diisodecyl oxalate and dioctyl adipate; ethyl phthalyl ethyl glycolate, butyl glycolate And glycolic acid esters such as phthalylbutyl.

  A coating film of the coating solution is formed by uniformly coating the coating solution prepared as described above on the surface of the undercoat layer. This coating operation can be performed using a normal coating means such as 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 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. A stimulable phosphor layer is formed by applying and drying the prepared coating solution on a support using a coating device such as a doctor blade, a roll coater, or a knife coater. The stimulable phosphor layer and the support may be bonded after the coating solution is applied and dried on the protective layer.

  The thickness of the photostimulable phosphor layer of the radiation image conversion panel 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 stimulable phosphor, etc. It is preferably selected from the range of 10 to 1000 μm, more preferably selected from the range of 10 to 500 μm.

  The phosphor sheet in which the phosphor layer is coated on the support is cut into a predetermined size. For cutting, any general method is possible, but from the viewpoint of workability and accuracy, a cosmetic cutting machine, a punching machine, or the like is desirable.

  The phosphor sheet cut to 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 applied between two heated rollers. Is mentioned. In the method of heating and fusing with an impulse sealer, heating and fusing under a reduced pressure environment is more effective in the sense of preventing displacement in the moisture-proof protective film of the phosphor sheet and eliminating moisture in the atmosphere. preferable.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, the embodiment of this invention is not limited to these.

Example In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, 2500 ml of BaI ₂ aqueous solution (1.75 mol / l) and 125 ml of EuBr ₃ aqueous solution (0.067 mol / l) were used in a reactor. I put it in. 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 stimulable phosphor particles.

  Next, the phosphor obtained was subjected to surface treatment of the photostimulable phosphor particles with a silane coupling agent shown in Table 1 using a Henschel mixer. Then, the photostimulable phosphor particles were surface-treated with a compound having the type fluorine compound shown in Table 1 using a Henschel mixer.

Comparative Example A photostimulable phosphor precursor was prepared in the same manner as in Example 1, and the surface treatment was performed on the photostimulable phosphor particles with a silane coupling agent and a fluorine-containing compound shown in Table 1 using a Henschel mixer. .

  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 stimulable phosphor particles obtained above, 15.8 g of polyurethane resin (manufactured by Sumitomo Bayer Urethane Co., Ltd., Desmolac 4125), bisphenol A type epoxy resin 2. 0 g was added to a mixed solvent of methyl ethyl ketone and toluene (1: 1) and dispersed by a propeller mixer to prepare a coating solution having a viscosity of 1.84 to 2.21 W. 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.

  The radiation image conversion panel was cut into a 10 cm × 10 cm square to produce a phosphor plate.

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 sensitivity after storage 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 in the state where the surface treatment of the stimulable phosphor particles is not performed is 1.

  As is clear from Table 1, the sample of the present invention can obtain a phosphor plate with little sensitivity deterioration due to moisture absorption.

  The initial sensitivity tends to be improved by coating with a fluorine-containing compound and a silane coupling agent because the fluorine-containing compound does not cause failure such as crushing, dispersing, and coating of the stimulable phosphor particles. It is estimated to be.

Claims (10)

A method for producing a photostimulable phosphor, comprising producing a photostimulable phosphor through the following process sequence.
(A) Step of generating stimulable phosphor (B) Step of coating the stimulable phosphor with a silane coupling agent (C) Covering the coated stimulable phosphor with a compound containing fluorine Process The method for producing a photostimulable phosphor according to claim 1, wherein the photostimulable phosphor is a compound represented by the following general formula (1).
General formula (1)
(Ba _1-x M ² _x ) FBryI _1-y X: aM ¹ , bLn, cO
Wherein M ¹ is at least one alkali metal atom selected from Li, Na, K, Rb and Cs, and M ² is at least one alkaline earth metal atom selected from Mg, Ca, Sr, Zn and Cd. , X is at least one halogen atom selected from Cl, Br and I, Ln is at least one rare earth element selected from Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er and Yb X, y, a, b, and c are 0 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.3, 0 ≦ a ≦ 0.05, 0 <b ≦ 0.2, and 0 <c, respectively. ≦ 0.1) A method for producing a photostimulable phosphor, characterized in that a photostimulable phosphor produced by a liquid phase method is produced through the following sequence of steps.
(A) Step of generating stimulable phosphor (B) Step of coating the stimulable phosphor with a silane coupling agent (C) Covering the coated stimulable phosphor with a compound containing fluorine Process 4. The method for producing a photostimulable phosphor according to claim 3, wherein the photostimulable phosphor produced by the liquid phase method is a compound represented by the general formula (1). The method for producing a photostimulable phosphor according to any one of claims 1 to 4, wherein the compound containing fluorine is a coating composition obtained by dissolving a fluorine-containing polymer with a fluorinated solvent. The method for producing a photostimulable phosphor according to any one of claims 1 to 5, wherein the silane coupling agent has a mercapto group. The method for producing a photostimulable phosphor according to any one of claims 1 to 5, wherein the silane coupling agent has a vinyl group. The fluorine concentration of the compound containing fluorine is 0.2 to 20% by mass with respect to the stimulable phosphor, and the silane coupling agent is 0.1 to 5% by mass with respect to the stimulable phosphor. The method for producing a photostimulable phosphor according to any one of claims 1 to 7. A photostimulable phosphor obtained by the method according to any one of claims 1 to 8, wherein the photostimulable phosphor represented by the general formula (1) is obtained. A radiation image conversion panel comprising the photostimulable phosphor according to claim 9.