JP2006071470A - Radiation image conversion panel and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation image conversion panel having uniform thickness coating, high coating property, and high graininess, and also to provide its manufacturing method. <P>SOLUTION: In this manufacturing method of the radiation image conversion panel that has a stimulable phosphor layer containing stimulable phosphor, stimulable phosphor layer coating liquid containing acrylic oligomer is applied onto a support body and is dried. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a radiation image conversion panel using a photostimulable phosphor and a method for manufacturing the same, and particularly to a radiation image conversion panel having a uniform coating thickness distribution, good coating properties, and excellent graininess. Regarding the method.

  Radiation images such as X-ray images are often used in fields such as disease diagnosis. The X-ray image is obtained by irradiating the phosphor layer (phosphor screen) with X-rays that have passed through the subject, thereby generating visible light, and then using this visible light as when taking a normal photograph. Thus, a so-called radiographic method in which a silver halide photographic light-sensitive material (hereinafter also simply referred to as a light-sensitive material) is irradiated and then developed to obtain a visible silver image is widely used.

  However, in recent years, a new method for extracting an image directly from a phosphor layer has been proposed in place of an image forming method using a photosensitive material having silver halide.

  In this method, the radiation transmitted through the subject is absorbed by the phosphor, and then the phosphor is excited by, for example, light or thermal energy, so that the radiation energy accumulated by the phosphor is absorbed as fluorescence. There is a method of emitting and detecting this fluorescence and imaging.

  Specifically, for example, a radiation image conversion method using a stimulable phosphor as described in U.S. Pat. No. 3,859,527 and JP-A-55-12144 is known.

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

  According to the above radiographic image reproduction method, a radiographic image with abundant information can be obtained with a much smaller exposure dose as compared with a radiographic method using a combination of a conventional radiographic film and an intensifying screen. Has the advantage.

  Thus, the stimulable phosphor is a phosphor that exhibits stimulating light emission when irradiated with excitation light after being irradiated with radiation, but practically, with excitation light having a wavelength in the range of 600 to 800 nm, Phosphors exhibiting stimulated emission in the wavelength range of 300 to 500 nm are generally used.

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

  Although the radiation image conversion method using the radiation image conversion panel is a very advantageous image forming method as described above, the radiation image conversion panel used in this method is also naturally high in sensitivity, and the image quality (sharpness, graininess, etc.) It is desirable to provide a good image.

  As a technique for improving the sensitivity, a coating liquid in which a white pigment is dispersed and contained in an appropriate binder is applied to a support, a light reflection layer is provided on the support, and a stimulable phosphor layer is formed thereon. There is a known method (for example, see Patent Document 1). By the way, the white pigment has a remarkably low reflectance in the near-ultraviolet region. Therefore, depending on the photostimulable phosphor used, the light reflecting property of the light reflecting layer cannot be said to be sufficiently high. The improvement in the sensitivity of the radiation image conversion panel due to the provision of the layer was not always satisfactory.

  Patent Document 2 discloses a technique in which an alkaline earth metal fluoride halide represented by a specific composition formula is used as a white pigment in a light reflecting layer provided between a support and a stimulable phosphor layer. As a result, improvement of light reflection characteristics, sensitivity, and sharpness is desired. However, this light reflecting layer is provided under the photostimulable phosphor layer, and the reflection of the photostimulated fluorescence is difficult to reach the surface of the radiation image conversion panel (stimulated fluorescence reading side), and the luminance improvement is insufficient. The problem became clear.

  As a method for producing a radiation image conversion panel, when a stimulable phosphor coating solution is applied and dried on a support to form a stimulable phosphor layer, phosphor particles having a relatively high specific gravity are dispersed in the coating solution. As a result, the dispersion of the coating liquid may precipitate in the liquid pool, or the dispersion in the coating liquid may agglomerate due to the effects of shearing during coating and drying wind during drying. In some cases, the viscosity of the coating solution varies in the coating width direction, resulting in a deterioration of the film thickness distribution, or coating failure such as coating stripes and coating unevenness.

  In order to apply the photostimulable phosphor layer on the support, a knife type coating apparatus suitable for high viscosity and thick film coating of the photostimulable phosphor layer is often used. In a knife-type coating apparatus, for example, the coating liquid sent by a liquid feed pump is temporarily stored in a liquid reservoir called a dam formed by a knife-type coating apparatus and a support on a back roll, and the collected coating is performed. The liquid is applied with a constant film thickness by being regulated by a knife (film thickness regulating member) on the back roll. Such knife type coating apparatuses are described in JP-A-63-69568, 63-69566, and 62-289266, and the supply of the coating liquid is generally performed from above the coating liquid dam. Or, it is often supplied by a pipe from a predetermined position on the wall surface of the coating liquid dam.

  Disadvantages of the knife-type coating apparatus described in these patents are that flow unevenness occurs in the coating liquid dam due to the flow rate when the coating liquid is supplied, resulting in non-uniform film thickness. In the case of a dispersion liquid in which solid particles are dispersed, the viscosity of the coating liquid dam is changed due to precipitation / aggregation of particles and flow unevenness, resulting in a non-uniform coating composition and problems of coating stripes. It is known.

  In order to solve such problems of flow unevenness and precipitation in the coating liquid dam, a stirring paddle capable of reciprocating in the width direction of the belt-like support body and the coating liquid in the coating liquid reservoir are fed into the belt-like support body. In order to uniformly stir in the width direction, a coating device is known in which a rotating body is provided to stir the coating liquid reservoir (see, for example, Patent Document 3).

However, if the rotating body is brought closer to a cylindrical shape, the stirring force may be reduced and the effect may be lost, and if the rotational speed is increased, the shearing near the cylinder and the surrounding liquid reservoir is greatly changed, and streaks are observed. May be. In addition, when the rotating body has a highly stirrer shape such as blades, it has a drawback that unevenness of the blade cycle is likely to occur, and in the low stirrer shape, flow unevenness and precipitation occur in the coating liquid dam. In some cases, it is necessary to use the coating solution after confirming whether or not the coating solution to be used is appropriate by conducting a preliminary experiment.
JP-A-56-12600 Japanese Patent Publication No. 3-7280 Japanese Patent Laid-Open No. 2001-70866

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a radiation image conversion panel having a uniform coating thickness distribution, good coatability, and excellent graininess, and a method for producing the same. It is to provide.

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

(Claim 1)
In a method for producing a radiation image conversion panel having a stimulable phosphor layer containing a stimulable phosphor, a stimulable phosphor layer coating solution containing an acrylic oligomer is coated on a support and dried. A method for manufacturing a radiation image conversion panel.

(Claim 2)
The method for producing a radiation image conversion panel according to claim 1, wherein the photostimulable phosphor is Eu-activated BaFI.

(Claim 3)
The method for producing a radiation image conversion panel according to claim 1, wherein the stimulable phosphor layer coating solution contains a polymer resin.

(Claim 4)
The method for producing a radiation image conversion panel according to claim 3, wherein the polymer resin has a urethane bond in the main chain.

(Claim 5)
A radiation image conversion panel obtained by the method for manufacturing a radiation image conversion panel according to claim 1.

  According to the present invention, it is possible to provide a radiation image conversion panel having a uniform coating thickness distribution, good coatability, and excellent graininess, and a method for producing the same.

  As a result of diligent research, the inventor of the present invention has disclosed a stimulable phosphor layer coating solution containing an acrylic oligomer in a method for producing a radiation image conversion panel having a stimulable phosphor layer containing a stimulable phosphor. It has been found that a method for producing a radiation image conversion panel having a uniform coating thickness distribution, good coatability and excellent graininess can be obtained by coating and drying the coating.

  The present invention will be described in detail below.

[Acrylic oligomer]
The present invention is characterized in that the stimulable phosphor layer coating solution contains an acrylic oligomer. Examples of the acrylic oligomer used in the present invention include those obtained by polymerizing the following monomers by a known method such as a solution polymerization method or a non-aqueous dispersion polymerization method. For bifunctional acrylic oligomers, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,3-butylene glycol (meth) acrylate, 1,4-butanediol Diacrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, pentaerythritol di (meth) acrylate, glycerol di (meth) acrylate, 1,1,1-trishydroxymethylethanedi For trifunctional acrylic oligomers such as (meth) acrylate, 1,1,1-trishydroxymethylpropanedi (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri ( T) acrylate, 1,1,1-trishydroxymethylethanetri (meth) acrylate, aliphatic tri (meth) acrylate, and other tetrafunctional acrylic oligomers such as pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) ) Acrylates, aliphatic tetra (meth) acrylates, etc., with 5 or more functional acrylic oligomers such as dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and various derivatives of these polyfunctional acrylic oligomers The oligomer obtained is mentioned.

  As the acrylic oligomer, commercially available products can be used. For example, M-309 and M-400 manufactured by Toagosei Co., Ltd., UV-3000B manufactured by Nippon Synthetic Chemical Co., Ltd. Examples include Karayad PAR-300 manufactured by Nippon Kayaku Co., Ltd., DOPA-17, DOPA-33, and DOPA-44 manufactured by Kyoeisha Chemical Co., Ltd.

  The reason why the object of the present invention is achieved when the acrylic oligomer according to the present invention is added is presumed to be because the acrylic oligomer suppresses unevenness of the coating film surface during coating and drying. As content of an acrylic oligomer, 0.01-10 mass% is preferable with respect to photostimulable phosphor particle, and 0.05-5 mass% is more preferable.

  Next, the photostimulable phosphor layer will be described.

  The photostimulable phosphor layer is mainly composed of photostimulable phosphor particles and a polymer resin, and is coated and formed on a support using a coater.

  Examples of the stimulable phosphor that can be used in the stimulable phosphor layer include a stimulable phosphor that exhibits stimulated emission in the wavelength range of 300 to 500 nm by excitation light having a wavelength in the range of 400 to 900 nm. Generally used.

[Stimulable phosphor]
Examples of the photostimulable phosphor that can be preferably used in the photostimulable phosphor layer according to the present invention will be given below, but the present invention is not limited thereto.

(1) (Ba _1-X , M (II) _X ) FX: yA described in JP-A No. 55-12145, wherein M (II) is Mg, Ca, Sr, Zn and Cd. At least one of them, 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 Is a rare earth element activated alkaline earth metal fluoride halide phosphor represented by a composition formula of 0 ≦ x ≦ 0.6 and y is 0 ≦ y ≦ 0.2; May contain the following additives.

a) X ', BeX ", M (III) X"" ₃ described in JP-A-56-74175, wherein X', X" and X '"are Cl, Br and I, respectively. And M (III) is a trivalent metal b) BeO, MgO, CaO, SrO, BaO, ZnO, Al ₂ O ₃ , Y ₂ O described in JP-A No. 55-160078 ₃ , metal oxides such as 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 and ThO ₂ c) -Zr, Sc described in -116777
d) B described in JP-A-57-23673
e) As and Si described in JP-A-57-23675
f) ML described in JP-A-58-206678, wherein M is at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs, and L is Sc. Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, In, and Tl. G) Baked product of tetrafluoroboric acid compounds 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 zirconium acid; NaX ′ described in JP-A-59-56479, wherein X ′ is at least one of Cl, Br and I h) Transition metals such as V, Cr, Mn, Fe, Co and Ni described in JP-A-59-56480; M (I) X ′, M described in JP-A-59-75200 ′ (II) X ″ ₂ , M (III) X ″ ″ ₃ , A, wherein M (I) is at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs , M ′ (II) represents at least one divalent metal selected from the group consisting of Be and Mg, and M (III) represents at least one trivalent metal selected from the group consisting of Al, Ga, In, and Tl. A is a metal oxide, and X ′, X ″, and X ′ ″ are each at least one halogen selected from the group consisting of F, Cl, Br, and I. i) JP-A-60-101173 M (I) X ′ described in the above formula, wherein M (I) is Rb and And at least one alkali metal selected from the group consisting of Cs, and X ′ is at least one halogen selected from the group consisting of F, Cl, Br and I. j) described in JP-A-61-2679 M (II) ′ X ′ ₂ .M (II) ′ X ″ ₂ , wherein M (II) ′ is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; X ′ And X ″ are at least one halogen selected from the group consisting of Cl, Br and I, respectively, and X ′ ≠ X ″; further, LnX ″ described in JP-A-61-264084 _{3 wherein} Ln is at least one rare earth element selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Yes; X ″ is F Cl, at least one halogen selected from the group consisting of Br and I.

(2) M (II) X ₂ · aM (II) X ′ ₂ : xEu ^{2+ described in} JP-A-60-84381 (where M (II) is a 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 ′; 1 ≦ a ≦ 10.0, x is 0 <x ≦ 0.2) The divalent europium-activated alkaline earth metal halide phosphor represented by the composition formula; Various additives may be included.

a) M (I) X ′ described in JP-A-60-166379, wherein M (I) is at least one alkali metal selected from the group consisting of Rb and Cs; B) at least one halogen selected from the group consisting of Cl, Br, and I b) KX ″, MgX ″ ″ ₂ , M (III) X ″ ″ ₃ , which are described in JP-A-60-222143 Wherein M (III) is at least one trivalent metal selected from the group consisting of Sc, Y, La, Gd and Lu; X ″, X ′ ″ and X ″ ″ are all F, Cl, Br and C) at least one halogen selected from the group consisting of I) c) B described in JP-A-60-228592, SiO ₂ , P ₂ O ₅ described in JP-A-60-228593, etc. Oxides, described in JP-A 61-120882 LiX ″, NaX ″, wherein X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I d) SiO described in JP-A-61-120883; SnX ″ ₂ described in JP-A-61-120885, wherein X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I. e) JP-A-61-235486 CsX ″, SnX ′ ″ ₂ , wherein X ″ and X ′ ″ are each at least one halogen selected from the group consisting of F, Cl, Br and I; CsX ″, Ln ³⁺ described in No. 235487, wherein 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, at least one rare earth element Tm, selected from the group consisting of Yb, and Lu.

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

  (4) M (II) OX: xCe described in JP-A-58-69281 (wherein M (II) is Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm. And at least one metal oxide selected from the group consisting of Y, Yb, and Bi; X is at least one of Cl, Br, and I; x is 0 <x <0.1) A cerium-activated trivalent metal oxyhalide phosphor represented by the formula:

  (5) M (I) X: xBi described in JP-A No. 62-25189, wherein M (I) is at least one alkali metal selected from the group consisting of Rb and Cs; A bismuth-activated alkali metal halide phosphor represented by a composition formula: at least one halogen selected from the group consisting of Cl, Br and I; and x is a numerical value in the range of 0 <x ≦ 0.2. .

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

(7) M (II) ₂ BO ₃ X: xEu ²⁺ described in JP-A-60-157099 (wherein M (II) is at least one selected from the group consisting of Ca, Sr and Ba) X is an 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) Divalent europium activated alkaline earth metal haloborate phosphor.

(8) M (II) ₂ (PO ₄ ) ₃ X: xEu ²⁺ described in JP-A-60-157100 wherein M (II) is selected from the group consisting of Ca, Sr and Ba At least one alkaline earth metal; 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) A divalent europium activated alkaline earth metal halophosphate phosphor represented.

(9) M (II) HX: xEu ²⁺ described in JP-A-60-217354 (wherein M (II) 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 Cl, Br and I; x is a numerical value in the range of 0 <x ≦ 0.2) Activated alkaline earth metal hydride phosphor.

(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) X and X ′ are at least one halogen selected from the group consisting of F, Cl, Br and I, respectively, and X ≠ X ′; and a is 0.1 <Numerical value in the range of a ≦ 10.0, and x is a numerical value in the range of 0 <x ≦ 0.2). A cerium activated rare earth composite halide phosphor represented by a composition formula.

(11) LnX ₃ · aM (I) X′3: xCe ³⁺ described in JP-A-61-21182, wherein Ln is at least selected from the group consisting of Y, La, Gd and Lu M (I) is at least one alkali metal selected from the group consisting of Li, Na, K, Cs and Rb; X and X ′ are each a group consisting of Cl, Br and I; At least one selected halogen; 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). Activated rare earth composite halide phosphor.

(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) Yes; 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 of.

(13) CsX: aRbX ′: xEu ²⁺ , wherein X and X ′ are at least one halogen selected from the group consisting of Cl, Br and I, respectively, described in JP-A No. 61-236888 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 Rubidium phosphor.

(14) M (II) X ₂ .aM (I) X ′: xEu ²⁺ , wherein M (II) is a group consisting of Ba, Sr and Ca described in JP-A-61-236890 M (I) is at least one alkali metal selected from the group consisting of Li, Rb and Cs; X and X ′ are each composed of Cl, Br and I 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). A divalent europium-activated composite halide phosphor represented.

  Among the photostimulable phosphors described above, a divalent europium activated alkaline earth metal fluoride halide phosphor containing iodine, a divalent europium activated alkali earth metal halide phosphor containing iodine, and iodine. Rare earth element-activated rare earth oxyhalide phosphors containing bismuth and bismuth activated alkali metal halide phosphors containing iodine are preferable because they exhibit high-luminance stimulated luminescence, and in particular, the stimulable phosphor is Eu. Preferably it is activated BaFI.

[Polymer resin]
The photostimulable phosphor according to the present invention is characterized in that it is contained in the photostimulable phosphor layer in a form dispersed in a polymer resin.

  As the polymer resin that can be used in the present invention, known polymer resins can be used together. For example, polyester, vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride. Copolymer, vinyl chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (nitrocellulose, etc.), styrene-butadiene copolymer, various synthetic rubber resins, phenol resin, Examples thereof include an epoxy resin, a urea resin, a melamine resin, a phenoxy resin, a silicon resin, an acrylic resin, and a urea formamide resin. Among these, in the present invention, a polymer resin having a urethane bond in the main chain is preferable.

[Polymer resin having urethane bond in the main chain]
Polymer resins having a urethane bond in the main chain are generally referred to as urethane resins, and by polyaddition reaction of polyisocyanates with active compounds such as polyols utilizing reactivity of isocyanate groups to active hydrogen compounds in the resin structure. The resulting urethane bond, urea (urea) bond, buret and allophanate bond and other bonds resulting from the reaction of active hydrogen with an active hydrogen, ester bond contained in the active hydrogen compound molecule, ether bond, amide bond, and It is a polymer compound containing uretdione, isocyanurate, carbodiimide and the like produced by the reaction between isocyanate groups.

  Generally, polyurethane resin has excellent mechanical properties, wear resistance, durability, and chemical resistance due to intermolecular secondary bonds such as urethane bonds and urea bonds with high cohesive energy present in the molecule. have. In addition, the performance can be greatly changed by controlling the types of raw materials used such as polyisocyanate and active hydrogen compound, composition ratio reaction conditions, and the like.

  Examples of the polyisocyanate used for the synthesis of the polyurethane resin include the following, but are not limited thereto. Toluene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate (TDI), 1,6-hexamethylene diisocyanate, 2,2,4 (2,4,4) -trimethylhexamethylene diisocyanate, p-phenylene diisocyanate, 4,4'-dicyclohexyl Methane diisocyanate, 3,3′-dimethyldiphenyl-4,4′-diisocyanate, dianisidine diisocyanate, m-xylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, tetramethylxylene diisocyanate, isophorone diisocyanate, 1,5 -Naphthalene diisocyanate, 1,4-cyclohexyl diisocyanate, lysine diisocyanate, dimethyltriphenylmethane tetraisocyanate , Triphenylmethane triisocyanate, tris (isocyanatophenyl) thiophosphate, urethane modified toluene diisocyanate, allophanate modified toluene diisocyanate, biuret modified toluene diisocyanate, isocyanurate modified toluene diisocyanate, urethane modified diphenylmethane diisocyanate, carbodiimide modified diphenylmethane diisocyanate, uretonimine modified diphenylmethane Diisocyanate, acylurea modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, etc.

  These isocyanate compounds may be used alone or in advance, a reaction product of a plurality of types of polyisocyanate, a reaction product of methanol or ethanol ethylene oxide adduct and polyisocyanate, or two or more per molecule. You may use as a compound which has a free isocyanate group obtained by reaction of the compound which has active hydrogen of this, and polyisocyanate.

  Specific methods for synthesizing polyurethane resins are disclosed in JP-A-5-127306, JP-A-6-67328, JP-A-6-293421, JP-A-4-96919, JP-A-58-63716, JP-A-58-80320, Nos. 63-301251, 56-151753, JP-A-2-269723, 7-10950 and the like. In addition, Gunter Autel's "Polyurethane Handbook" (1985), Imai Yoshio's "Polyurethane Foam" (1987), Technical Information Association's "Water-Based Paint and Coating Technology" (1992), etc. also have detailed descriptions of polyurethane synthesis methods.

  Examples of commercially available polyurethane resins include Superflex series 107, 110, 126, 150, 160, 190, 300, 361, 410, 460, 750, 820, and Superflex E series manufactured by Daiichi Kogyo Seiyaku Co., Ltd. E-2000, E-2500, E-4500. Takeda Pharmaceutical Co., Ltd. Takelac W Series W-6015, W-621, W-511, XW-75-P15, W-512A, W-635, W-7004, XW-97-W6, AW-605, ACW-54HD, Takelac XW series containing silanol groups, Pandex series manufactured by Dainippon Ink & Chemicals, Nipponporu series manufactured by Nippon Polyurethane Industry, etc. In addition, examples of the heat-reactive water-based polyurethane resin include Elastron series manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Takenate Pharmaceutical Co., Ltd. Takenate WB series WB-700, WB-710, WB-720, WB-730, WB- 920 or the like. Of these, those having an MDI skeleton are particularly preferred in the present invention, and an example thereof is Nipponporan 2304 manufactured by Nippon Polyurethane Industry Co., Ltd.

  A stimulable phosphor layer coating solution is used in the production of the radiation image conversion panel. This is achieved by adding the polymer resin and the photostimulable phosphor particles in a suitable organic solvent, stirring, mixing, for example, using a disperser, a ball mill, etc. The phosphor is prepared so that it is uniformly dispersed. Examples of the solvent used for preparing the stimulable phosphor layer coating solution include lower alcohols such as methanol, ethanol, n-propanol and n-butanol, hydrocarbons containing chlorine atoms such as methylene chloride and ethylene chloride, acetone, Ketones such as methyl ethyl ketone and methyl isobutyl ketone, aromatic compounds such as toluene, benzene, cyclohexane, cyclohexanone and xylene, esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate and butyl acetate, dioxane, ethylene glycol monoethyl ester And ethers such as ethylene glycol monomethyl ester and mixtures thereof.

  In the stimulable phosphor layer coating solution, if necessary, a dispersant for improving the dispersibility of the stimulable phosphor in the coating solution, or in the stimulable phosphor layer after panel formation. Various additives such as a plasticizer for improving the bonding force between the polymer resin and the photostimulable phosphor may be mixed.

  Examples of the dispersant include phthalic acid, stearic acid, caproic acid, lipophilic surfactant and the like. Examples of plasticizers include phosphoric esters such as triphenyl phosphate, tricresyl phosphate and diphenyl phosphate, phthalic esters such as diethyl phthalate and dimethoxyethyl phthalate, ethyl phthalyl ethyl glycolate, butyl phthalbutyl glycolate and the like For example, 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 oxalic acid, and the like.

  The stimulable phosphor layer coating solution is usually 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 onto the support by using a known coating coater such as a doctor blade, roll coater, knife coater, extrusion coater, etc. Formation of the photostimulable phosphor layer is completed.

  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, and the mixing ratio of the polymer resin and the stimulable phosphor. Although it varies depending on the like, 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 photostimulable phosphor layer is coated on the support is cut into a predetermined size. For cutting, any general method can be used, but a cosmetic cutting machine, a punching machine, etc. are preferable from the viewpoint of workability and accuracy.

  The radiation image conversion panel of the present invention is preferably provided with a protective film (also referred to as a protective film) for physically and chemically protecting the surface of the photostimulable phosphor layer. It can be appropriately selected according to the like.

  As a protective layer provided in the radiation image conversion panel of the present invention, a polyester film, a polymethacrylate film, a nitro having a excitation light absorption layer having a haze ratio measured by the method described in ASTM D-1003 of 5% or more and less than 60% A cellulose film, a cellulose acetate film, etc. can be used, but a stretched film such as a polyethylene terephthalate film or a polyethylene naphthalate film is preferable as a protective layer in terms of transparency and strength. Furthermore, these polyethylene terephthalate films Further, a vapor-deposited film obtained by vapor-depositing a thin film such as a metal oxide or silicon nitride on a polyethylene terephthalate film is more preferable from the viewpoint of moisture resistance.

  The haze ratio of the film used in the protective layer can be easily adjusted by selecting the haze ratio of the resin film to be used, and a resin film having an arbitrary haze ratio can be easily obtained industrially. As a protective film for a radiation image conversion panel, an optically highly transparent film is assumed. As such a highly transparent protective film material, various plastic films having a haze value in the range of 2 to 3% are commercially available. In order to obtain the effect of the present invention, the preferred haze ratio is 5% or more and less than 60%, and more preferably 10% or more and less than 50%. If the haze ratio is less than 5%, the effect of eliminating image unevenness and linear noise is low, and if it is 60% or more, the effect of improving sharpness is impaired.

In the present invention, the film used in the protective layer is made to be optimal moisture-proof by laminating a plurality of vapor-deposited films obtained by depositing a metal oxide or the like on a resin film or resin film in accordance with the required moisture-proof property. In consideration of preventing moisture absorption deterioration of the photostimulable phosphor, the moisture permeability is preferably at least 50 g / m ² · day or less. There is no restriction | limiting in particular as a lamination method of a resin film, You may use any well-known method.

  In addition, it is preferable to provide an excitation light absorption layer between the laminated resin films so that the excitation light absorption layer is protected from physical impact and chemical alteration and stable plate performance can be maintained for a long period of time. Moreover, the excitation light absorption layer may be provided at a plurality of locations, or a colorant may be contained in the adhesive layer for stacking to form an excitation light absorption layer.

  The protective film may be in close contact with the photostimulable phosphor layer through an adhesive layer, but has a structure (hereinafter also referred to as a sealing or sealing structure) provided to cover the phosphor surface. Is more preferable. For sealing the phosphor plate, any known method may be used, but the outermost resin layer on the side in contact with the phosphor sheet of the moisture-proof protective film may be a moisture-proof resin film. This is one of the preferred forms in that the protective film can be fused and the phosphor sheet can be efficiently sealed. Furthermore, a moisture-proof protective film is disposed above and below the phosphor sheet, and the upper and lower moisture-proof protective films are heated and fused with an impulse sealer or the like in a region where the periphery is outside the periphery of the phosphor sheet. The sealing structure is preferable because it can prevent moisture from entering from the outer peripheral portion of the phosphor sheet. In addition, the moisture-proof protective film on the support surface side is a laminated moisture-proof film formed by laminating one or more aluminum films, so that moisture entry can be reduced more reliably. It is easy and preferable. In the method of heat-sealing with the 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 outermost resin layer and the phosphor surface having heat-sealing properties on the side where the phosphor surface of the moisture-proof protective film is in contact may or may not be adhered. Here, the state of non-adhesion means that the phosphor surface and the moisture-proof protective film are optically and mechanically discontinuous even when the phosphor surface and the moisture-proof protective film are in point contact. It is a state that can be treated as a body. The resin film having the above-mentioned heat-fusibility is a resin film that can be fused with a commonly used impulse sealer. For example, ethylene vinyl acetate copolymer (EVA), polypropylene (PP) film, polyethylene ( PE) film and the like can be mentioned, but the present invention is not limited to this.

[Support]
Various polymer materials are used as the support used in the radiation image conversion panel of the present invention. In particular, a material that can be processed into a flexible sheet or web as an information recording material is suitable. In this respect, cellulose acetate film, polyester film, polyethylene terephthalate film, polyethylene naphthalate film, polyamide film, polyimide A plastic film such as a film, a triacetate film or a polycarbonate film is preferred.

  The layer thickness of these supports varies depending on the material of the support to be used, but 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 photostimulable phosphor layer.

  From the viewpoint of increasing the reflectivity of the support and improving the brightness of the radiation image conversion panel, polyethylene terephthalate containing bubbles is preferably used. Polyethylene terephthalate containing bubbles increases the reflectivity for stimulated fluorescence by incorporating bubbles in polyethylene terephthalate by the method described in JP-A-3-76727 and 6-226894, and the brightness of the radiation image conversion panel A support with improved resistance can be produced. Moreover, as a commercial item, there exists polyethylene terephthalate containing air bubbles, such as Toray Industries, Inc. E60L.

  Further, the thickness of the polyethylene terephthalate support containing the bubbles is generally 80 to 1000 μm, and preferably 50 to 500 μm from the viewpoint of handling.

  The surface of these supports may be a smooth surface, or may be a matte surface for the purpose of improving the adhesion between the reflective layer, the light absorbing layer and the stimulable 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.

  The undercoat layer mainly contains a polymer resin that can be crosslinked by a crosslinking agent and a crosslinking agent.

  The polymer resin contained in the undercoat layer is not particularly limited. For example, polyurethane, polyester, vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, chloride Vinyl-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (nitrocellulose, etc.), styrene-butadiene copolymer, various synthetic rubber resins, phenol resin, epoxy resin, urea resin , Melamine resin, phenoxy resin, silicon resin, acrylic resin, urea formamide resin, and the like. Among them, polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral, nitrocellulose and the like can be mentioned, and the average glass transition temperature (Tg) is preferably 25 ° C. or more, and more preferably 25 to 200 ° C. It is preferable to have a Tg of

  There is no restriction | limiting in particular as a crosslinking agent contained in an undercoat layer, For example, polyfunctional isocyanate and its derivative (s), melamine and its derivative (s), an amino resin, its derivative (s), etc. can be mentioned. It is particularly preferable to use a polyfunctional isocyanate compound, and examples thereof include Coronate HX and Coronate 3041 manufactured by Nippon Polyurethane.

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

  First, the polymer resin and the cross-linking agent are added to a suitable solvent, for example, a solvent used in the preparation of the phosphor layer coating solution, and mixed well to prepare an undercoat layer coating solution.

  The amount of the crosslinking agent used varies depending on the characteristics of the intended radiation image conversion panel, the type of material used for the phosphor layer and the support, the type of polymer resin used for the undercoat layer, etc., but the support for the phosphor layer Considering the maintenance of the adhesive strength with respect to the polymer resin, it is preferably added at a ratio of 50% by mass or less, particularly preferably 15 to 50% by mass with respect to the polymer resin.

  The thickness of the undercoat layer varies depending on the characteristics of the intended radiation image conversion panel, the type of material used for the phosphor layer and the support, the type of polymer resin and crosslinker used in the undercoat layer, but in general, It is preferable that it is 3-50 micrometers, and it is especially preferable that it is 5-40 micrometers.

  In order to complete the reaction between the polymer resin contained in the undercoat layer and the cross-linking agent after coating the undercoat layer on the support and before applying the stimulable phosphor layer, It is preferable to perform heat treatment for 2 to 100 hours. The heat treatment method is not particularly limited, and any method can be used as long as it is a temperature-controlled room in which the prepared undercoat layer-coated sample such as a sheet or roll can be completely stored and the temperature and humidity can be controlled. Also good. The heat treatment conditions may be 40 to 150 ° C. for 2 to 100 hours, preferably 55 to 100 ° C. and 5 to 50 hours.

  After forming the undercoat layer on the support, when performing the heat treatment in the form of being laminated in the form of a roll or in the form of being laminated in the form of a sheet, a protective sheet is inserted between each laminated sample, and after the heat treatment After removing the protective sheet, a phosphor layer is preferably applied. By adopting this method, it is possible to effectively prevent blocking between the undercoat layer and the back surface of the support during the heat treatment.

  The protective sheet that can be used in the present invention is not particularly limited as long as the material to be used is used, as long as adhesion or fusion can be prevented and the adhesive strength between the protective sheet and the undercoat layer or the back of the support is extremely weak. For example, various resin films used as the above-described protective film can be appropriately selected and used. In addition, a release agent is preferably applied to the protective sheet in order to facilitate peeling after the heat treatment.

  In the present invention, the above crosslinking agent can be used for other layers without being limited to the undercoat layer.

  In the present invention, a polymer resin and a crosslinking agent are added to a suitable solvent, for example, a solvent used in the preparation of a stimulable phosphor layer coating solution, and this is mixed well to prepare a coating solution.

  The amount of crosslinking agent used varies depending on the characteristics of the intended radiation image conversion panel, the type of materials used for the stimulable phosphor layer and the support, the type of polymer resin used in the undercoat layer, etc. Considering maintenance of the adhesive strength of the phosphor layer to the support, it is preferably added at a ratio of 50% by mass or less, particularly preferably 15 to 50% by mass with respect to the polymer resin.

  In the present invention, it is better to perform the compression process at the stage of obtaining the phosphor sheet. The compression treatment means that a stimulable phosphor layer coating solution is coated on a support or a support provided with an undercoat layer and dried under desired conditions to form a stimulable phosphor layer and After making a body sheet, for example, it refers to processing by applying temperature and pressure between a highly smooth nip roller having a diameter of 1 to 100 cm and a heatable roller facing the nip roller. By applying this compression treatment, the first effect is that it is possible to improve the filling rate of the stimulable phosphor in the stimulable phosphor layer, to achieve high emission luminance and sharpness, and to the second effect. As an effect of the above, by setting the pressure and heating conditions to specific conditions, it is possible to obtain high uniformity of the phosphor sheet during the compression treatment.

  The compression method using a calender roll is not particularly limited. For example, it is described in “Resin Processing Technology Handbook (Edition of Polymer Society): Nikkan Kogyo Shimbun, June 12, 1965”. Can be applied with reference to the method.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. Unless otherwise specified, “%” in the examples represents “mass%”.

Example << Preparation of Radiation Image Conversion Panel >>
(Preparation of photostimulable phosphor)
In order to synthesize a stimulable phosphor precursor of europium activated barium fluoroiodide, 2780 ml of BaI ₂ aqueous solution (3.6 mol / L) and 27 ml of EuI ₃ aqueous solution (0.15 mol / L) were placed in a reactor. . The reaction mother liquor in this reactor was kept at 83 ° C. with stirring. Next, 322 ml of an aqueous ammonium fluoride solution (8 mol / L) was injected into the reaction mother liquor using a roller pump to form a precipitate. After completion of the injection, the mixture was kept warm and stirred for 2 hours to age the precipitate. Next, the precipitate was separated by filtration, washed with ethanol, and then vacuum dried to obtain europium activated barium fluoroiodide crystals. In order to prevent changes in particle shape due to sintering during sintering and particle size distribution change due to inter-particle fusion, 0.2% by mass of ultrafine powder of alumina is added, and the crystal surface is stirred thoroughly with a mixer. An ultrafine powder of alumina was uniformly adhered to the surface. 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, classification was performed to prepare phosphor particles having an average particle diameter of 4 μm.

(Preparation of phosphor layer coating solution 1)
480 g of the above prepared europium activated barium fluoroiodide phosphor, and a polyurethane resin (Nipporan 2304, Tg of 30 ° C.) in such an amount that the resin amount / (phosphor amount + resin amount) is 15 volume% (solid ratio) MDI, solid content 35%, manufactured by Nippon Polyurethane Industry Co., Ltd.) is added to a 6: 2: 2 mixed solvent of cyclohexanone: methyl ethyl ketone: toluene, dispersed with a propeller mixer, and fluorescent with a viscosity of 3-4 Pa · s. Body layer coating solution 1 was prepared. The viscosity was measured at 25 ° C. using a bismetholone viscometer.

(Preparation of phosphor layer coating solutions 2 to 5)
In the preparation of the phosphor layer coating solution 1, the presence or absence of the polyurethane resin, the type and amount of the acrylic oligomer were changed as shown in Table 1, and phosphor layer coating solutions 2 to 5 were similarly prepared.

(Preparation of undercoat layer coating solution)
100 parts by mass of polyester resin (Byron 53SS, manufactured by Toyobo Co., Ltd.) with a Tg of 30 ° C. and 3 parts by mass of Coronate HX (manufactured by Nippon Polyurethane Industry Co., Ltd.), which is a polyfunctional isocyanate compound, are used as a crosslinking agent. The mixture was added to a 1: 1 mixed solvent of methyl ethyl ketone: toluene and dispersed with a propeller mixer to prepare an undercoat layer coating solution having a viscosity of 500 mPa · s.

(Preparation of phosphor sheet 1)
<Application of undercoat layer>
On the black polyethylene terephthalate support that has been kneaded with carbon having a thickness of 250 μm, the undercoat layer coating solution prepared above is applied using a knife coater so that the dry film thickness is 30 μm, and then dried. A support with a pulling layer was produced.

<Application of phosphor layer>
The prepared phosphor layer coating solution 1 was applied on a support with an undercoat layer and dried so as to have a dry film thickness of 180 μm, thereby preparing a phosphor sheet 1.

(Preparation of phosphor sheets 2 to 5)
Phosphor sheets 2 to 5 were produced in the same manner except that the phosphor layer coating solution 1 was changed to the phosphor layer coating solutions 2 to 5 in the production of the phosphor sheet 1.

<< Production of moisture-proof protective film >>
The thing of the following structure (A) was used as a protective film of the fluorescent substance layer coating surface side of each produced said fluorescent substance sheet.

Configuration (A)
VMPET12 // VMPET12 // PET12 // Sealant film PET: Polyethylene terephthalate Sealant film: CPS (casting polypropylene) or LLDPE (low density linear polyethylene) is used in the heat-fusible film VMPET: Alumina-deposited PET (commercial product: Toyo) (Made by Metalizing)
The number described behind each resin film indicates the film thickness (μm) of the film.

  The above “//” means a dry lamination adhesive layer, which means that the thickness of the adhesive layer is 2.5 μm. A two-component reaction type urethane adhesive was used as an adhesive for dry lamination. At this time, by adding an organic blue colorant (Zavon First Blue 3G, manufactured by Hoechst Co.) dispersed and dissolved in methyl ethyl ketone in advance to the used adhesive solution, all of the adhesive layer becomes an excitation light absorbing layer. did.

  The protective film on the back side of the support of the phosphor sheet was a dry laminate film having a structure of sealant film / aluminum foil 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.

<< Production of Radiation Image Conversion Panels 1-5 >>
After cutting each of the prepared phosphor sheets into squares each having a side of 45 cm, using the moisture-proof protective film prepared above, the periphery is fused and sealed using an impulse sealer under reduced pressure, Radiation image conversion panels 1 to 5 were produced. 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 heater used for fusion was 8 mm wide.

<Evaluation>
The following evaluation was performed using each phosphor sheet and each radiation image conversion panel produced as described above. The obtained results are shown in Table 1.

(Thickness distribution)
From the start of application of the prepared phosphor sheet to 150 m, the thickness distribution of the coating film was measured and evaluated according to the following rank.

  The thickness distribution of the film thickness was determined from the following calculation formula using a film thickness tester manufactured by Anritsu Co., Ltd., measuring a width of 500 mm between the coating widths of 5 mm.

Thickness distribution (%) = (maximum value−minimum value) / average value × 100
○: Less than 4% thickness distribution △: 4-6% thickness distribution
X: Over 6% thickness distribution (applicability)
From the start of application of the produced phosphor sheet to 150 m, the presence or absence of visual muscle failure and uneven application were evaluated according to the following rank.

<Muscle failure>
○: No muscle failure by 150 m from the start of application Δ: Muscle failure is observed at 50 m from the start of application ×: Muscle failure is observed at less than 50 m from the start of application <Coating unevenness>
○: No application unevenness Δ: Partial application unevenness is observed ×: Application unevenness is observed according to the pulsation interval of the coating liquid (granularity)
After the produced radiation image conversion panel is uniformly irradiated with X-rays having a tube voltage of 80 kVp, it is excited by scanning with a He—Ne laser beam (633 nm) from the phosphor layer coating surface side and emitted from the phosphor layer. The photostimulated luminescence is received by a photoreceiver (photoelectron image multiplier with spectral sensitivity S-5), the image is read, and the image is output using a laser writing type film printer. Sense) was evaluated in three stages by visual observation in accordance with the following criteria. In addition, it was judged that below Δ is practically not suitable for diagnosis by X-ray.

○: A uniform solid image with no graininess △: There is a graininess and the uniformity is impaired ×: The texture is clearly rough and there is no uniformity

  As is clear from Table 1, the sample of the present invention containing the acrylic oligomer in the stimulable phosphor layer coating solution has a uniform film thickness distribution and a coating property (muscle failure and coating unevenness) compared to the comparative example. It can be seen that it is good and has excellent graininess.

Claims (5)

In a method for producing a radiation image conversion panel having a stimulable phosphor layer containing a stimulable phosphor, a stimulable phosphor layer coating solution containing an acrylic oligomer is coated on a support and dried. A method for manufacturing a radiation image conversion panel. The method for producing a radiation image conversion panel according to claim 1, wherein the photostimulable phosphor is Eu-activated BaFI. The method for producing a radiation image conversion panel according to claim 1, wherein the stimulable phosphor layer coating solution contains a polymer resin. The method for producing a radiation image conversion panel according to claim 3, wherein the polymer resin has a urethane bond in the main chain. A radiation image conversion panel obtained by the method for manufacturing a radiation image conversion panel according to claim 1.