Line camera, radiation inspection apparatus, in-line inspection method and inspection method using the same

Abstract

Provided is a high-brightness scintillator panel for which brightness deterioration resulting from being irradiated with radiation is suppressed. This scintillator panel comprises a substrate and a scintillator layer including a fluorescent substance. The scintillator layer comprises a binder resin having a π-conjugated system structure configured from 7 or more atoms and a glass transition point of 30-430 °C. The film thickness of the scintillator layer is 50-800 μm.

Description

Technical Field

[0001] The present invention relates to a scintillator panel, a radiation detector using the same, a line camera, a radiation inspection apparatus, an in-line inspection method, and an inspection method using the same.

Background Art

[0002] Conventionally, in fields where inspection using an X-ray image is required, a detection method using a film has been widely used. However, since an X-ray image using a film is analog image information, in recent years, digital radiation detection devices such as flat panel detectors (FPDs) have been developed.

[0003] In an indirect conversion type FPD, a scintillator panel is used to convert X-rays into visible light. The scintillator panel has a scintillator layer containing a phosphor such as gadolinium oxysulfide (GOS), and the phosphor emits light upon irradiation with X-rays. The light emitted from the scintillator panel is converted into an electrical signal using a sensor (photoelectric conversion layer) having a thin film transistor (TFT) or a charge coupled device (CCD), thereby converting the X-ray information into digital image information.

[0004] For an X-ray detector, which is a radiation detection device using X-rays as radiation, it is desirable to have high luminance. Also, from the viewpoint of durability, it is desirable to have excellent adhesion between the scintillator panel and the support. Therefore, it has been studied to make improvements to the phosphor particles and binder resin contained in the scintillator layer (see, for example, Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] In industrial applications, in in-line inspections of foods, electronic components, etc., it is required to shorten the inspection time (tact time) required per product. Further, as a method for shortening the tact time, a method of performing inspection while continuously irradiating X-rays is employed. However, in the techniques described in Patent Documents 1 to 3, there is a problem that the luminance decreases during the use period of the detector due to continuous irradiation of X-rays.

[0007] As a result of investigations by the present inventors, it has been found that the above problem is due to the deterioration (for example, coloring, etc.) of the binder resin in the scintillator layer when used under high-dose radiation irradiation conditions.

[0008] An object of the present invention is to provide a high-luminance scintillator panel in which luminance deterioration due to radiation irradiation is suppressed, in view of the above problems.

Means for Solving the Problems

[0009] That is, the present invention is a scintillator panel having a substrate and a scintillator layer containing a phosphor, wherein the scintillator layer contains a binder resin having a π-conjugated structure composed of 7 or more atoms, and the glass transition point of the binder resin is 30 to 430 ° C., and the film thickness of the scintillator layer is 50 to 800 μm.

Effects of the Invention

[0010] According to the present invention, a high-luminance scintillator panel excellent in radiation resistance can be obtained.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0012] Hereinafter, a preferred configuration of a scintillator panel according to an embodiment of the present invention and a radiation detector using the same will be described with reference to the drawings as appropriate, but the present invention is not limited thereto.

[0013] The scintillator panel of the present invention has at least a base material and a scintillator layer. The scintillator layer absorbs the energy of radiation such as incident X-rays and emits light in the range of electromagnetic waves having a wavelength of, for example, 300 nm to 800 nm, that is, light in the range from ultraviolet light to infrared light centered on visible light.

[0014] The scintillator layer contains at least a phosphor and a binder resin having a π-conjugated structure composed of 7 or more atoms. The phosphor has the function of absorbing the energy of radiation such as X-rays and emitting light. The binder resin has the function of connecting and fixing a plurality of phosphor particles and fixing the relative positions of the phosphor particles in the scintillator layer.

[0015] FIG. 1 schematically shows one aspect of an X-ray detector including a scintillator panel according to an embodiment of the present invention. The X-ray detector 1 has a scintillator panel 2, an output substrate 3, and a power supply unit 12.

[0016] The scintillator panel 2 has a base material 5 and a scintillator layer 4. The scintillator layer 4 contains a phosphor 6 and a binder resin 7.

[0017] The output substrate 3 has a photoelectric conversion layer 9 and an output layer 10 on the substrate 11. The photoelectric conversion layer 9 is generally one that forms pixels having a photosensor (not shown), for example, in the photoelectric conversion layer, facing the scintillator layer 4, with the pixels arranged in a matrix. It is also possible to have a diaphragm layer 8 on the photoelectric conversion layer 9. It is preferable to bond or closely adhere the light-emitting surface of the scintillator panel 2 and the photoelectric conversion layer 9 of the output substrate 3 via the diaphragm layer 8.

[0018] FIG. 2 schematically shows another aspect of the X-ray detector 1 including the scintillator panel according to the embodiment of the present invention. The X-ray detector 1 has a scintillator panel 2, an output substrate 3, and a power supply unit 12.

[0019] The scintillator panel 2 has a base material 5 and a scintillator layer 4, and the scintillator layer 4 is partitioned by a partition wall 13. The scintillator layer 4 contains a phosphor 6 and a binder resin 7. The output substrate 3 has a photoelectric conversion layer 9 and an output layer 10 on the substrate 11. The photoelectric conversion layer 9 generally forms pixels having a photosensor (not shown). It is also possible to have a diaphragm layer 8 on the photoelectric conversion layer 9. The light emitted by the scintillator layer 4 reaches the photoelectric conversion layer 9, is photoelectrically converted, and output.

[0020] (Binder resin) The binder resin contained in the scintillator layer has a π-conjugated structure composed of 7 or more atoms. By having a π-conjugated structure composed of 7 or more atoms, the binder resin has a structure capable of resonance stabilization, and discoloration of the binder resin due to radiation irradiation is suppressed. By suppressing the discoloration of the binder resin due to radiation irradiation, even when the scintillator panel is used under high-dose radiation irradiation conditions, a decrease in luminance can be suppressed, and the long life of the scintillator panel can be achieved.

[0021] When it is said that the binder resin "has a π-conjugated system structure", it means that the structure in the resin has alternating single bonds and multiple bonds, and there are multiple multiple bonds. When it is said that "it has a π-conjugated system structure composed of 7 or more atoms", it is a structure that has alternating single bonds and multiple bonds as described above, and in that structure, the number of atoms constituting the multiple bonds is 7 or more. As an example of the number of atoms constituting the π-conjugated system structure of the binder resin, methyl polymethacrylate is 0, polystyrene is 6, polyethylene terephthalate is 10, polyhydroxystyrene is 6, polycarbonate is 6, and poly(4,4'-oxydiphenylene pyromellitimide) is 14. The π-conjugated system structure composed of 7 or more atoms can be confirmed by calculating the number of atoms constituting the multiple bonds in a structure that has alternating single bonds and multiple bonds and has multiple multiple bonds after confirming the structure of the binder resin by the method described later.

[0022] The binder resin preferably has a π-conjugated system structure composed of 30 or fewer atoms. By having a π-conjugated system structure composed of 30 or fewer atoms, it is possible to suppress the absorption wavelength of the binder resin from shifting to a longer wavelength, so the transmittance in the visible light region increases, the initial coloring of the binder resin is reduced, and the brightness is further improved.

[0023] The transmittance of a solution containing 2.5% by weight of the binder resin used in the present invention at an optical path length of 1 cm and a wavelength of 400 nm is preferably 85% or more, more preferably 90% or more. When the transmittance of a solution containing 2.5% by weight of the binder resin at an optical path length of 1 cm and a wavelength of 400 nm is 85% or more, the initial coloring of the binder resin is reduced. Therefore, the light emitted by the phosphor can be suppressed from being absorbed in the binder resin, the attenuation of light in the phosphor layer is reduced, and the luminance is further improved. Here, the transmittance of a solution containing 2.5% by weight of the binder resin at an optical path length of 1 cm and a wavelength of 400 nm is a value measured using an ultraviolet-visible spectrophotometer (for example, U-4100 manufactured by Hitachi High-Tech Corporation). The solvent of the solution uniformly dissolves the binder resin, and is not particularly limited as long as the transmittance of the solvent alone at an optical path length of 1 cm and a wavelength of 400 nm is 80% or more.

[0024] The binder resin used in the present invention preferably has a structure represented by the following general formula (1) or (2) as a repeating unit in the main chain.

[0025]

Chemical formula

[0026] In the above general formulas (1) and (2), X 1 , X 2 , Y 1 and Y 2 each independently represent a divalent organic group. Ar represents an aromatic hydrocarbon group. t represents an integer of 1 or 2.

[0027] Since Ar is an aromatic hydrocarbon group, in the general formulas (1) and (2), the portion of Ar-C(=O) has a structure capable of resonance stabilization. The aromatic hydrocarbon group may be substituted or unsubstituted. Preferred substituents in the case of being substituted include an aliphatic hydrocarbon group, a carboxy group, an amino group, a hydroxyl group, an alkoxy group, a halogen, and a silyl group. The aromatic hydrocarbon group is preferably an aromatic hydrocarbon group having 6 to 25 carbon atoms including substituents.

[0028] Specific examples of the aromatic hydrocarbon group include, for example, a phenylene group, a naphthylene group, an anthracenylene group, and a phenanthrenylene group. Two or more of these may be contained. Among these, from the viewpoints of the solvent solubility, transparency, and color tone of the resin, a phenylene group or a naphthylene group is preferable, and a phenylene group is particularly preferable. Specific examples of Ar are divalent groups derived from these groups in the general formula (1) and trivalent to tetravalent groups derived from these groups in the general formula (2).

[0029] In the general formula (1), X 1 is a divalent organic group. As the divalent organic group, a substituted or unsubstituted hydrocarbon group, an organic group derived from a substituted or unsubstituted diol, an organic group derived from a substituted or unsubstituted diamine, and a group formed by combining two or more of these are preferable.

[0030] Examples of the hydrocarbon group include an aliphatic hydrocarbon group and an aromatic hydrocarbon group. The aliphatic hydrocarbon group may be linear or branched, and may be partially or entirely cyclic. Also, it may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. At least a part of the hydrogen in the aliphatic hydrocarbon group may be substituted with a halogen or the like. At least a part of the hydrogen in the aromatic hydrocarbon group may be substituted with a halogen or the like. The number of carbon atoms of the hydrocarbon group is preferably 2 or more, more preferably 4 or more. The number of carbon atoms of the hydrocarbon group is preferably 25 or less, more preferably 20 or less.

[0031] The organic group derived from a diol refers to the residue after the hydrogen atoms are each eliminated from the two hydroxyl groups of the diol. Examples of the diol include aliphatic diols such as ethylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylene glycol, tetramethylene glycol, 1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-isopropyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, neopentyl glycol, hexanediol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and aromatic diols such as bisphenol A. Two or more of these may be contained.

[0032] The organic group derived from a diamine refers to the residue after one hydrogen atom is eliminated from each of the two amino groups of the diamine. Examples of the diamine include aliphatic diamines such as 1,6-hexamethylenediamine, 2-methyl-1,5-diaminopentane, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,12-dodecamethylenediamine, 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 4,4'-diaminodicyclohexylpropane, 4,4'-diamino-3,3'-dimethyldicyclohexylmethane, 1,4-diaminocyclohexane, 1,4-bis(aminomethyl)-cyclohexane, 2,6-bis(aminomethyl)-norbornane, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, bis-(4-amino-3-methyl-cyclohexyl)methane, isophoronediamine, and aromatic diamines such as m-xylylenediamine, p-xylylenediamine, bis(4-aminophenyl)propane. Two or more of these may be contained.

[0033] In general formula (1), Y 1is a divalent organic group. Examples of the divalent organic group include a substituted or unsubstituted hydrocarbon group, an ether group, a thioether group, a carbonyl group, a sulfonyl group, an imino group, and a group formed by combining two or more of these. Among these, from the viewpoints of suppressing discoloration and deterioration of the resin by radiation irradiation and ease of synthesis, a substituted or unsubstituted hydrocarbon group, an ether group, a carbonyl group, and a group formed by combining two or more of these are preferable. Examples of the substituent for the hydrocarbon group include halogen and the like. Y 1 When Y is a hydrocarbon group, the number of carbon atoms of the hydrocarbon group is preferably 1 or more, more preferably 3 or more. The number of carbon atoms of the hydrocarbon group is preferably 15 or less, more preferably 10 or less.

[0034] Specific examples of the binder resin having the structure represented by the general formula (1) in the main chain include, for example, a polyester resin (for example, when X 1 is an organic group derived from diol and Y 1 is a carbonyl group), a polyetheretherketone resin (for example, when X 1 is a hydrocarbon group and Y 1 is a group formed by combining an ether group and a hydrocarbon group), a polyamide resin (for example, when X 1 is an organic group derived from diamine and Y 1 is a carbonyl group), and the like.

[0035] In the general formula (2), X 2 is a divalent organic group. Examples of the divalent organic group include a substituted or unsubstituted hydrocarbon group, and a group formed by combining a substituted or unsubstituted hydrocarbon group with one or more groups selected from the group consisting of an ether group, a thioether group, an ester group, a carbonyl group, a sulfonyl group, an imino group, and an amide group.

[0036] Among these, a substituted or unsubstituted hydrocarbon group, and a group formed by combining a substituted or unsubstituted hydrocarbon group with an ether group and / or a sulfonyl group are preferable. Specific examples thereof include, for example, the following structures.

[0037] [Chemical]

[0038] In general formula (2), Y 2 is a divalent organic group. Examples of the divalent organic group include a substituted or unsubstituted hydrocarbon group, an ether group, a thioether group, an ester group, a carbonyl group, a sulfonyl group, an imino group, an amide group, an imide group, and a group formed by combining two or more of these. Among these, from the viewpoint of suppressing discoloration and deterioration of the resin by radiation irradiation, a substituted or unsubstituted hydrocarbon group, an ether group, an ester group, a sulfonyl group, a carbonyl group, an amide group, an imide group, and a group formed by combining two or more of these are preferable. The number of carbon atoms of the hydrocarbon group is preferably 1 to 8. When t is 2 in general formula (2), the plurality of Y 2 may be the same as or different from each other. Also, the plurality of Y 2 may form a cyclic structure.

[0039] Specific examples of the binder resin having the structure represented by general formula (2) in the main chain include, for example, a polyimide resin (for example, when Y 2 is an imide group), a polyetherimide resin (for example, when Y 2 is a group formed by combining an ether group, a hydrocarbon group, and an imide group), a polyamideimide resin (for example, when Y 2 contains an amide group), and the like.

[0040] The structures of the resins represented by general formulas (1) to (2) can be confirmed by a method of attributing the peaks detected using a nuclear magnetic resonance apparatus (NMR).

[0041] The binder resin used in the present invention is preferably amorphous. Since the binder resin is amorphous, its solvent solubility is improved, and in the method for manufacturing a scintillator panel described later, it becomes possible to uniformly mix the phosphor and the binder resin, so that a uniform phosphor layer can be formed. As a result, it is possible to suppress the local occurrence of luminance deterioration of the scintillator panel due to the coloring of the binder resin. In addition, compared with resins that require heat melting such as hot melt resins, a high-temperature heating step in the manufacturing process of the scintillator panel becomes unnecessary, so the selection of the substrate becomes easy, and it is possible to reduce deterioration such as discoloration of the binder resin during heating at high temperature. As a result, the luminance of the scintillator panel is further improved. Here, the "amorphous" means a case where when the binder resin is measured by the powder X-ray diffraction method, substantially no peak due to the crystal structure is observed, and only a broad halo is observed.

[0042] The glass transition temperature of the binder resin used in the present invention is 30 to 430 °C. The lower limit of the glass transition temperature is 30 °C, and it is preferably 40 °C or higher. When the glass transition temperature of the binder resin is 30 °C or higher, the generation of radicals in the binder resin due to radiation irradiation and the accompanying intermolecular crosslinking, cleavage, and decomposition can be reduced. Thereby, it is possible to suppress coloring due to the reaction between the cleavage site and other molecules and the change in the structure of the binder resin. As a result, it is possible to suppress the luminance deterioration of the scintillator panel due to the coloring of the binder resin and the deformation of the scintillator panel due to the decrease in the mechanical properties of the binder resin.

[0043] On the other hand, the upper limit of the glass transition temperature of the binder resin is 430 °C, more preferably 270 °C or lower, and even more preferably 260 °C or lower. When the glass transition temperature is higher than 430 °C, the binder resin is likely to be colored even before X-ray irradiation, and the luminance decreases.

[0044] In the present invention, the glass transition temperature of the binder resin is a value measured using a differential thermal analyzer (for example, differential type differential thermal balance TG8120; manufactured by Rigaku Corporation).

[0045] In the present invention, the weight average molecular weight (Mw) of the binder resin is preferably in the range of 5,000 to 100,000. When the weight average molecular weight Mw of the binder resin is 5,000 or more, the binder resin has sufficient strength to hold the phosphor, and it is possible to suppress chipping, cracking of the scintillator layer, and a decrease in luminance. In addition, it is less susceptible to the influence of changes in the molecular structure due to radiation irradiation, and it is possible to suppress discoloration and deterioration of the mechanical properties of the scintillator panel. When the Mw of the binder resin is 100,000 or less, it is possible to fill the phosphor particles at a high density, and the luminance is improved.

[0046] The dispersity (Mw / Mn) obtained by dividing the weight average molecular weight (Mw) of the binder resin by the number average molecular weight (Mn) is preferably 1.5 to 5.0. When the dispersity of the binder resin is 1.5 or more, the production yield of the binder resin can be improved. When the dispersity of the binder resin is 5.0 or less, the generation of hardly soluble components in the solvent can be suppressed, and the variation in luminance in the scintillator layer can be suppressed.

[0047] Here, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the binder resin are molecular weights measured and calculated by the gel permeation chromatography (GPC) method, and refer to conversion values based on a polystyrene sample with a known molecular weight. Specifically, it can be measured using a gel permeation chromatograph GPC (GPC-22) / differential refractive index detector RI (manufactured by Tosoh Corporation, RI-8020 type), and can be calculated by measuring using monodisperse polystyrene (manufactured by Tosoh Corporation) as a standard substance.

[0048] The binder resin used in the present invention preferably has an energy level difference Eg between the highest occupied molecular orbital and the lowest unoccupied molecular orbital of 2.0 eV or more and 4.2 eV or less, more preferably 2.7 eV or more and 4.1 eV or less. When the Eg of the binder resin is 2.0 eV or more, the light emitted by the phosphor can be suppressed from being absorbed in the binder resin, and the attenuation of light in the phosphor layer becomes small, so the luminance is further improved. Since the energy released when the electrons in the binder resin excited by radiation return to the ground state is about the same as or lower than the average binding energy between the atoms constituting the binder resin when the Eg of the binder resin is 4.2 eV or less, the probability of dissociation of the bonds between the atoms of the binder resin can be reduced. As a result, it is possible to reduce the probability of generation of radicals in the binder resin and / or reduce the reactivity of the generated radicals, so that the coloring of the binder resin due to the reaction caused by the radicals is suppressed and the luminance deterioration is further suppressed.

[0049] In the present invention, Eg of the binder resin is a value calculated using a Tauc plot. Specifically, the optical constants (refractive index n, extinction coefficient k) for each wavelength are obtained using a spectroscopic ellipsometer (for example, FE-5000; manufactured by Otsuka Electronics Co., Ltd.), the absorption coefficient α is calculated from the extinction coefficient k, and the energy E of each wavelength is plotted on the x-axis and (Eα) 2 is plotted on the y-axis (Tauc plot). For the S-shaped rising curve obtained by the plot, a tangent line passing through the inflection point is drawn, and the intersection of the tangent line and the x-axis is obtained as Eg. When there is a baseline separately from the x-axis in the Tauc plot, the intersection of the tangent line and the baseline becomes Eg.

[0050] The scintillator layer may contain a binder resin other than the above as long as the effects of the present invention are not impaired. Examples of such binder resins include acrylic resins, cellulose-based resins, epoxy resins, melamine resins, phenol resins, urea resins, vinyl chloride resins, butyral resins, polyvinyl acetals, silicone resins, polyester resins, polyamide resins, polyimide resins, polyamideimide resins, polycarbonate resins, polyketone resins, polyether resins, polyethylene, polypropylene, polycarbonate, polystyrene, polyvinyl toluene, polyvinyl pyrrolidone, polyacrylamide, polyvinyl acetate, aromatic hydrocarbon resins, polyalkylene polyamine resins, polybenzimidazole resins, polypyrrole resins, polythiophene resins, and the like.

[0051] (Phosphor) The phosphor used in the scintillator panel of the present invention may be any substance that emits light in the range from ultraviolet light to infrared light centered on visible light upon irradiation with radiation. For example, it may be either an inorganic phosphor or an organic phosphor.

[0052] Examples of inorganic phosphors include sulfide-based phosphors, germanate-based phosphors, halide-based phosphors, barium sulfate-based phosphors, hafnium phosphate-based phosphors, tantalate-based phosphors, tungstate-based phosphors, rare earth silicate-based phosphors, rare earth oxysulfide-based phosphors, rare earth phosphate-based phosphors, rare earth oxyhalide-based phosphors, alkaline earth metal phosphate-based phosphors, alkaline earth metal fluorohalide-based phosphors, and the like.

[0053] Examples of the rare earth silicate-based phosphor include a cerium-activated rare earth silicate-based phosphor. Examples of the rare earth oxysulfide-based phosphor include a praseodymium-activated rare earth oxysulfide-based phosphor, a terbium-activated rare earth oxysulfide-based phosphor, and a europium-activated rare earth oxysulfide-based phosphor. Examples of the rare earth phosphate-based phosphor include a terbium-activated rare earth phosphate-based phosphor. Examples of the rare earth oxyhalide phosphor include a terbium-activated rare earth oxyhalide-based phosphor and a thulium-activated rare earth oxyhalide-based phosphor. Examples of the alkaline earth metal phosphate-based phosphor include a europium-activated alkaline earth metal phosphate-based phosphor. Examples of the alkaline earth metal fluorohalide-based phosphor include a europium-activated alkaline earth metal fluorohalide-based phosphor.

[0054] Examples of the organic phosphor include p-terphenyl, p-quaterphenyl, 2,5-diphenyloxazole, 2,5-diphenyl-1,3,4-oxadiazole, naphthalene, diphenylacetylene, stilbene, and the like.

[0055] Two or more of these may be contained. Among these, a phosphor selected from the rare earth oxysulfide-based phosphors is preferable, and among the rare earth oxysulfides, gadolinium oxysulfide is preferable in terms of luminous efficiency and chemical stability. Gadolinium oxysulfide is preferably activated with terbium, europium, or praseodymium.

[0056] Examples of the shape of the phosphor include particulate, columnar, flaky, and the like. Among these, the particulate phosphor is preferable. By forming the phosphor into a particulate shape, the phosphor can be more uniformly dispersed in the scintillator layer, so that the unevenness of the light emission of the phosphor in the scintillator layer can be suppressed and uniform light emission can be achieved.

[0057] The average particle size of the phosphor is preferably from 0.5 to 50 μm, more preferably from 3.0 to 40 μm, and even more preferably from 4.0 to 30 μm. When the average particle size of the phosphor is 0.5 μm or more, the conversion efficiency from radiation to visible light is further improved, and the luminance can be further improved. In addition, aggregation of the phosphor can be suppressed. On the other hand, when the average particle size of the phosphor is 50 μm or less, the smoothness of the surface of the scintillator layer is excellent, and generation of bright spots in the image can be suppressed.

[0058] Here, the average particle size of the phosphor in the present invention refers to the particle size at which the cumulative distribution of the particle size becomes 50%, and can be measured using a particle size distribution measuring device (for example, MT3300; manufactured by Nikkiso Co., Ltd.). More specifically, the phosphor is introduced into a sample chamber filled with water, ultrasonic treatment is performed for 300 seconds, and then the particle size distribution is measured. The particle size at which the cumulative distribution becomes 50% is defined as the average particle size. The time required for the luminescence intensity of the phosphor to become 1 / e times the initial luminescence intensity is preferably 100 μs or less. When the time required to become 1 / e times is 100 μs or less, in an inspection method of continuously imaging a subject including an in-line inspection described later, it is possible to suppress the X-ray image of each subject from remaining in the image of the subsequent subject. As a result, high-speed and continuous inspection becomes possible. The decay time of the luminescence intensity of the phosphor can be measured by a known method. Specifically, a method using ultraviolet light from a fluorescence lifetime measuring device (for example, Quantaurus-Tau C11367-24; Hamamatsu Photonics K.K.) as excitation light, or a method using radiation from a device composed of an optical fiber, a photodiode, and a photo sensor amplifier as an excitation source can be mentioned. As a method for shortening the decay time of the luminescence intensity of the phosphor, taking gadolinium oxysulfide as an example, a method of using an activator different from terbium can be mentioned. In particular, when praseodymium is activated, the decay time becomes shorter.

[0059] The volume ratio of the phosphor to the binder resin in the scintillator layer is preferably phosphor:binder resin = 80:20 to 95:5. By setting the volume ratio of the phosphor to 80% or more, the content of the binder resin that discolors upon radiation exposure is reduced, and attenuation of the light emitted within the scintillator layer can be suppressed, thus improving the luminance. The volume ratio of the phosphor to the binder resin is more preferably phosphor:binder resin = 83:17 to 95:5, and even more preferably phosphor:binder resin = 85:15 to 95:5. On the other hand, by setting the volume ratio of the phosphor to 95% or less, the binding force between the phosphor particles by the binder resin can be maintained even after radiation exposure, thereby suppressing chipping and cracking of the scintillator layer and further improving the adhesion strength between the substrate and the scintillator layer. In addition, the dispersibility of the phosphor during formation of the scintillator layer can be improved, and variations in luminance within the scintillator layer can be suppressed.

[0060] (Other elements of the scintillator layer) The scintillator layer may contain a dispersant. By containing a dispersant, aggregation and sedimentation of the phosphor particles in the phosphor paste described later can be suppressed, and the pot life can be extended. In addition, since a uniform dispersion state of the phosphor particles in the phosphor paste can be maintained, uneven distribution of the phosphor particles in the scintillator layer can be suppressed, and variations in luminance within the scintillator layer can be suppressed. As the dispersant, those having an anionic functional group are preferred, and those having a carboxy group, a sulfone group and / or a phosphate group are preferred.

[0061] The scintillator layer may further contain a dispersant, a plasticizer, a crosslinking agent, a surface conditioner, an antistatic agent, metal compound particles, etc.

[0062] The film thickness of the scintillator layer is preferably increased to increase the amount of phosphor that emits light and improve the luminance, and can be appropriately set according to the quality of X-rays. In the present invention, it is 50 to 800 μm, more preferably 70 to 600 μm, and even more preferably 100 to 400 μm. When the film thickness is 50 μm or more, within the range where the effect of the present invention is not impaired against the discoloration of the binder resin due to radiation irradiation, the selection of the phosphor particle diameter with respect to the film thickness is possible, so that a decrease in luminance can be suppressed. When the film thickness is 800 μm or less, since the optical path length from the light emitted in the scintillator layer, particularly the light emitted on the substrate side, to the photoelectric conversion layer is short, the influence of the discoloration of the binder resin due to radiation irradiation is reduced. As a result, attenuation of light in the scintillator layer can be reduced, and a decrease in luminance can be suppressed. In addition, since deterioration of mechanical properties due to radiation irradiation can be suppressed, a decrease in the binding force between phosphors by the binder resin and the adhesion strength between the substrate and the scintillator layer can be suppressed. Within the above range, the film thickness uniformity is also excellent, and the influence of luminance variation due to unevenness on the surface of the scintillator layer with respect to the film thickness is reduced.

[0063] When the scintillator layer has a laminated structure of two or more layers, the relationship between the thickness Td of the scintillator layer (lower scintillator layer) on the substrate side and the thickness Tt of the scintillator layer (upper scintillator layer) laminated thereon is preferably in the range of Tt / (Td + Tt) being 0.4 to 0.9, and more preferably in the range of 0.6 to 0.9.

[0064] The brightness L of the scintillator panel of the present invention * is preferably 75 or more, and more preferably 80 or more. The brightness L * being 75 or more makes it possible to suppress the attenuation of the light emitted by the phosphor in the scintillator layer, and the luminance is further improved.

[0065] The chromaticity a of the scintillator panel of the present invention * is preferably -10.0 to 10.0, and more preferably -6.0 to 6.0. The chromaticity a *By being -10.0 to 10.0, it becomes possible to suppress the attenuation of the light emitted by the phosphor, particularly the light with a wavelength longer than around 450 nm, in the scintillator layer, and the luminance is further improved.

[0066] The chromaticity b of the scintillator panel of the present invention * is preferably -15.0 to 15.0, more preferably -10.0 to 10.0, and even more preferably -6.0 to 6.0. The chromaticity b * By being -15.0 to 15.0, it becomes possible to suppress the attenuation of the light emitted by the phosphor, particularly the light with a wavelength shorter than around 600 nm, in the scintillator layer, and the luminance is further improved.

[0067] (Base material) As the material constituting the base material used for the scintillator panel of the present invention, those having high radiation transparency are preferable, and examples include various glasses, polymer materials, metals, etc. Examples of the glass include quartz, borosilicate glass, chemically strengthened glass, etc. Examples of the polymer material include polyesters such as cellulose acetate and polyethylene terephthalate (PET), polyamide, polyimide, triacetate, polycarbonate, carbon fiber reinforced resin, etc. Examples of the metal include aluminum, iron, copper, etc. Two or more of these may be used. Among these, particularly polymer materials with high radiation transparency are preferable. Also, materials excellent in flatness and heat resistance are preferable.

[0068] From the viewpoint of weight reduction of the scintillator panel, the thickness of the base material is, for example, preferably 2.0 mm or less, more preferably 1.0 mm or less, and even more preferably 0.5 mm or less when using a glass substrate. Also, in the case of a base material made of a polymer material, it is preferably 3.0 mm or less, more preferably 1.0 mm or less. The thickness of the base material in the present invention can be calculated by cutting out the cross-section of the substrate using a microtome and then observing 10 locations each using a scanning electron microscope (for example, the field emission type scanning electron microscope "S-4800" manufactured by Hitachi, Ltd.) and measuring the average thickness.

[0069] The base material may have a metal layer on the surface on the scintillator layer side. When the base material has a metal layer, regardless of the color and thickness of the base material, it is possible to increase the reflectivity of the base material. The metal layer can be formed on the base material by a known method. Specifically, layers of aluminum, silver, and alloys thereof can be formed on the surface of the base material by methods such as physical vapor deposition (PVD) method and chemical vapor deposition (CVD) method.

[0070] When a polymer material is used as the base material, from the viewpoints of reflectivity, strength, and heat resistance, it is preferable to use polyester as the main component. Here, the "main component" in the present invention means a component of 50% by mass or more. A white polyester containing polyester as the main component and further containing materials having different refractive indexes is more preferable.

[0071] Polyester is a polycondensate of a diol and a dicarboxylic acid. Examples of the diol include ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, trimethylene glycol, and tetramethylene glycol. Examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, adipic acid, and sebacic acid. Examples of the polyester include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene-p-oxybenzoate, poly-1,4-cyclohexylene dimethylene terephthalate, and polyethylene-2,6-naphthalenedicarboxylate (PEN).

[0072] Examples of the materials having different refractive indexes include white pigments such as ceramic particles such as zinc oxide, zirconium oxide, titanium oxide, gadolinium oxide, gadolinium oxysulfide, and high refractive index glass.

[0073] Since the base material preferably has high radiation transmittance, it preferably does not contain elements of the 6th period or higher of the periodic table, and more preferably does not contain elements of the 5th period or higher. In particular, a base material composed of elements in the 4th period or lower is suitable because it has high radiation transmittance. In the present invention, not containing high-period elements means that the content of high-period elements in the base material is less than 0.1% by mass.

[0074] From the viewpoints of weight reduction of the scintillator panel and radiation transmittance, the base material preferably has a small specific gravity. Specifically, the specific gravity of the base material is preferably 1.2 g / cm 3 or less, more preferably 0.9 g / cm 3 or less, and even more preferably 0.7 g / cm 3 or less. On the other hand, from the viewpoint of further suppressing breakage and wrinkle generation during the production of the base material and further improving the handleability, the specific gravity of the base material is preferably 0.5 g / cm 3 or more.

[0075] The base material preferably has an easy-adhesion layer on the surface on the phosphor layer side. By having the easy-adhesion layer, the adhesion strength between the scintillator layer and the base material can be further improved.

[0076] Examples of the material for the easy - adhesion layer include acrylic resins, epoxy resins, urethane resins, polyester resins, etc. Two or more of these may be contained. Among them, it is preferable to use a polyester resin as the main component. A polyester resin having a glass transition temperature of 10 to 80 °C is more preferable. For example, when PET is used as the base material, an aromatic polyester having residues such as terephthalic acid and isophthalic acid with a structure similar to PET is preferable. As the aromatic polyester, a saturated copolymerized polyester having a weight - average molecular weight of 2,000 to 30,000 is preferable, and further, an amorphous solvent - soluble saturated copolymerized polyester having a weight - average molecular weight of 2,000 to 30,000 is preferable. As the amorphous solvent - soluble saturated copolymerized polyester having a weight - average molecular weight of 2,000 to 30,000, the amorphous solvent - soluble type of "Nitigo Polyester" (registered trademark) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. can be preferably used. The glass transition temperature of the resin can be measured using a differential thermal analyzer (for example, differential type differential thermal balance TG8120; manufactured by Rigaku Corporation).

[0077] The easy - adhesion layer may contain a powder having a refractive index different from that of the main - component polyester resin. By containing the powder, light diffusion in the direction parallel to the support can be more suppressed. The refractive index difference Δn between the polyester and the powder is preferably 0.2 or more. From the viewpoint of the refractive index difference from the resin which is the main component of the easy - adhesion layer, inorganic powder is preferable. Examples of the inorganic powder include those exemplified as the inorganic powder in the above - mentioned surface layer. Titanium oxide powder is particularly preferable from the viewpoint of high refractive index. Here, the refractive index of the polyester resin can be measured using a refractometer (Abbe refractometer 4T; manufactured by Atago Co., Ltd., light source: sodium D - line, measurement temperature 25 °C) for a resin film obtained by coating and drying a solution in which the polyester resin is dissolved in a soluble organic solvent such as methyl ethyl ketone. Also, the refractive index of the inorganic powder is disclosed in "Inorganic Chemistry Handbook" (Gihodo), "Dictionary for Effective Use of Fillers" (Taiseisha), "Ceramic Engineering Handbook" (The Ceramic Society of Japan), etc.

[0078] The base material may have an adhesive layer and a support on the side opposite to the surface where the scintillator layer is present. By having a support, in the process of manufacturing the scintillator panel described later, the stiffness of the base material is increased, so that it is possible to prevent the base material from breaking during handling.

[0079] The material constituting the support preferably has high radiation transmissivity. Examples of the material include cellulose acetate, polyester, polyamide, polyimide, triacetate, polycarbonate, and carbon fiber reinforced resins containing these and carbon fibers. The material constituting the support may be the same as the material of the base material.

[0080] Examples of the material constituting the adhesive layer include acrylic resin, epoxy resin, urethane resin, polyester resin, etc. Among them, since it can be adhered at a low temperature, an optically clear adhesive sheet (OCA) obtained by processing an acrylic adhesive material or the like into a sheet shape is preferable. Among them, since it can be adhered at a low temperature, an optically clear adhesive sheet (OCA) obtained by processing an acrylic adhesive material or the like into a sheet shape is preferable. hesive;OCA) is preferable. hesive;OCA) is preferable.

[0081] (Partition wall) The scintillator panel of the present invention preferably has a partition wall that partitions the scintillator layer.

[0082] The material constituting the partition wall is preferably one that can form a partition wall with high strength and heat resistance. For example, inorganic materials and polymer materials are preferable. Here, the "inorganic material" in the present invention refers to a compound composed of a simple part of carbon compounds (allotropes of carbon such as graphite or diamond) and elements other than carbon. Note that "consisting of inorganic substances" does not strictly exclude the presence of components other than inorganic substances, and the presence of components other than inorganic substances to the extent of impurities contained in the inorganic substances themselves as raw materials or impurities mixed in during the manufacturing process of the partition wall is allowed.

[0083] When the partition wall is made of an inorganic material, it is preferable that the main component is glass. Glass refers to an inorganic amorphous solid containing silicate. When the main component of the partition wall is glass, the strength, durability, and heat resistance of the partition wall are enhanced, and deformation and damage are less likely to occur in the formation process of the reflective layer and the phosphor filling process described later. In the embodiments of the present invention, "the main component is glass" means that 50 to 100% by mass of the material constituting the partition wall is glass.

[0084] In particular, it is preferable that the proportion of the low softening point glass, which is a glass with a softening point of 650 °C or lower, in the partition wall is 95% by volume or more, and more preferably 98% by volume or more, when the volume of the partition wall portion is 100% by volume. When the content rate of the low softening point glass is 95% by volume or more, the surface of the partition wall is likely to be flattened in the firing process. As a result, it becomes easier to uniformly form a reflective layer on the surface of the partition wall of the scintillator panel. As a result, the reflectance increases and the luminance can be further enhanced.

[0085] Examples of components that can be used as components other than the low softening point glass include high softening point glass powder and ceramic powder, which are glasses with a softening point exceeding 650 °C. These powders facilitate adjusting the shape of the partition wall in the partition wall formation process. In order to increase the content rate of the low softening point glass, the content of components other than the low softening point glass is preferably less than 5% by volume.

[0086] When the partition wall is made of a polymer material, it is preferably composed of one or more compounds (P) selected from the group consisting of polyimide, polyamide, polyamideimide, polybenzoxazole, and acrylic resin. By forming the partition wall from the compound (P), it is possible to form a fine partition wall with a high aspect ratio and a smooth surface. When producing a photosensitive resin composition using the compound (P), the components of the photosensitive material are not particularly limited. For example, a radical-polymerizable negative photosensitive resin composition obtained by adding a polyfunctional acrylic monomer and a photoinitiator to the compound (P), a cationic-polymerizable negative photosensitive resin composition obtained by adding an epoxy compound and a photoinitiator to the compound (P), a photo-solubilizable positive photosensitive resin composition obtained by adding a naphthoquinone-based photosensitizer to the compound (P), and the like can be mentioned. Among these, from the viewpoint of being able to form a partition wall having a high aspect ratio, a cationic-polymerizable negative photosensitive resin composition containing an epoxy compound is preferable.

[0087] When the partition wall is composed of the compound (P), it preferably has a phenolic hydroxyl group. By having a phenolic hydroxyl group, appropriate solubility of the resin in an alkaline developer can be obtained, so a high contrast between the exposed portion and the unexposed portion can be obtained, and a desired pattern can be formed.

[0088] The partition wall preferably further contains an epoxy compound. Since the epoxy compound can improve the processability without impairing the heat resistance and mechanical strength of the compound (P), it becomes easier to form a partition wall having a desired shape. As a result, the filling amount of the phosphor can be further increased, and the luminance can be further improved.

[0089] In order not to impair the properties of the compound (P), the content of the epoxy compound in the partition wall is preferably not more than the content of the compound (P) in terms of mass fraction. When the partition wall contains components other than the compound (P) and the epoxy compound, the total of their contents is preferably not more than the total amount of the compound (P) and the epoxy compound in terms of mass fraction.

[0090] As the epoxy compound, known ones etc. can be used, and aromatic epoxy compounds, alicyclic epoxy compounds and aliphatic epoxy compounds are included.

[0091] (Reflection layer) It is preferable that the surfaces of the partition walls and the base material of the scintillator panel have a reflection layer, particularly a metal reflection layer. By having a reflection layer, the light emitted in the cell partitioned by the partition walls by irradiation with radiation can efficiently reach the detector side, and the luminance is likely to be improved.

[0092] The material constituting the reflection layer is not particularly limited as long as it has a function of reflecting the electromagnetic wave emitted from the phosphor. For example, metal oxides such as titanium oxide and aluminum oxide, and metals such as silver and aluminum can be mentioned. Two or more of these may be included.

[0093] The material constituting the reflection layer is preferably one with a high reflectance even when it is a thin film. By making it a thin film, a decrease in the internal volume of the cell can be suppressed and the amount of phosphor to be filled can be increased, so the luminance of the scintillator panel is likely to be improved. Therefore, the reflection layer is preferably made of a metal, more preferably silver, aluminum, and alloys thereof. From the viewpoint of discoloration resistance in the atmosphere, it is preferably a silver alloy containing palladium and copper.

[0094] The thickness of the reflection layer can be appropriately set according to the required reflection characteristics and is not particularly limited. For example, the thickness of the reflection layer is preferably 10 nm or more, more preferably 50 nm or more. Also, the thickness of the reflection layer is preferably 500 nm or less, more preferably 300 nm or less. When the thickness of the reflection layer provided on the partition wall is 10 nm or more, the scintillator panel can suppress light from leaking through the partition wall and obtain sufficient light shielding properties, and as a result, the sharpness is improved. When the thickness of the reflection layer is 500 nm or less, the unevenness on the surface of the reflection layer is less likely to increase and the reflectance is less likely to decrease.

[0095] The reflective layer preferably has a protective layer on its surface. Even when an alloy with poor discoloration resistance in the atmosphere or the like is used for the reflective layer, the protective layer can reduce discoloration, suppress a decrease in the reflectance of the metal reflective layer due to the reaction between the metal reflective layer and the scintillator layer, and improve the luminance more.

[0096] (Protective layer) As the protective layer, either an inorganic protective layer or an organic protective layer can be preferably used. As the protective layer, an inorganic protective layer and an organic protective layer can also be laminated and used in combination.

[0097] The inorganic protective layer is suitable as a protective layer because of its low water vapor permeability. The inorganic protective layer can be formed by a known method such as sputtering. The material of the inorganic protective layer is not particularly limited. Examples of the material of the inorganic protective layer include oxides such as silicon oxide, indium tin oxide, and gallium zinc oxide, nitrides such as silicon nitride, and fluorides such as magnesium fluoride. Among these, as the material of the inorganic protective layer, it is preferable to use silicon nitride because of its low water vapor permeability and the fact that the reflectance of silver hardly decreases during the formation of the inorganic protective layer.

[0098] The thickness of the inorganic protective layer is not particularly limited. As the thickness of the inorganic protective layer, for example, it is preferably 2 nm or more, more preferably 5 nm or more. Also, the thickness of the inorganic protective layer is preferably 300 nm or less, more preferably 100 nm or less. When the thickness is 2 nm or more, the scintillator panel can have a greater effect of suppressing a decrease in luminance in the use environment. When the thickness is 300 nm or less, coloring due to the inorganic protective layer can be suppressed and the luminance can be further improved. The thickness of the inorganic protective layer can be measured in the same manner as the thickness of the organic protective layer described later.

[0099] The organic protective layer is preferably a polymer compound with excellent chemical durability. For example, it preferably contains polysiloxane or an amorphous fluororesin as a main component. Here, the "amorphous fluororesin" refers to a case where when a fluorine-containing resin is measured by the powder X-ray diffraction method, peaks due to the crystal structure are not substantially observed, and only a broad halo is observed.

[0100] The organic protective layer can be easily formed by known methods such as solution coating and spray coating.

[0101] The thickness of the organic protective layer is preferably 0.05 μm or more, more preferably 0.2 μm or more. Also, the thickness of the organic protective layer is preferably 10 μm or less, more preferably 5 μm or less. When the thickness of the organic protective layer is 0.05 μm or more, the scintillator panel 2 can have a greater effect of suppressing luminance reduction. Also, when the thickness of the organic protective layer is 10 μm or less, the scintillator panel can increase the volume inside the cell and fill a sufficient amount of phosphor, thereby further improving the luminance. In the embodiments of the present invention, the thickness of the organic protective layer can be measured by scanning electron microscope observation. Note that the organic protective layer formed in the organic protective layer forming step described later tends to be thin on the side surface near the top of the partition wall and thick on the side surface near the bottom. Therefore, when there is such a difference in thickness, the thickness of the organic protective layer refers to the thickness on the side surface of the central portion in the height direction of the partition wall.

[0102] (Method for manufacturing a scintillator panel) In the present invention, the method for manufacturing a scintillator panel particularly includes, for example, a method of forming a scintillator layer by applying a phosphor paste containing a phosphor, a binder resin having a π-conjugated structure composed of 7 or more atoms, and other components as necessary on a substrate, and performing heat drying or exposure as necessary.

[0103] As a method for applying the phosphor paste, for example, there are mentioned application methods using a screen printing method, a bar coater, a roll coater, a die coater, a blade coater, and the like. Among these, it is preferable to apply using a roll coater or a die coater because it is easy to apply even for a thick film so that the film thickness of the scintillator layer becomes uniform. Among die coaters, the application method using a slit die coater enables adjustment of the scintillator layer thickness by the discharge amount, and the thickness of the scintillator layer can be adjusted with high precision.

[0104] The phosphor paste may contain an organic solvent in addition to the components described above as components for forming the scintillator layer. The organic solvent is preferably a good solvent for a binder resin having a π-conjugated structure composed of 7 or more atoms, and a plasticizer, a dispersant, a surface conditioner, etc. contained as necessary. Examples of such organic solvents include ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, triethylene glycol monobutyl ether acetate, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, polyethylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monobutyl ether acetate, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, ethylene glycol phenyl ether, diethylene glycol phenyl ether, hexylene glycol, isopropyl alcohol, methyl ethyl ketone, cyclohexanone, propyl alcohol, butyl alcohol, terpineol, benzyl alcohol, tetrahydrofuran, dihydroterpineol, γ-butyrolactone, dihydroterpinyl acetate, 3-methoxy-1-butanol, 3-methoxy-3-methyl-1-butanol, 3-methoxy-3-methyl-1-butyl acetate, N,N-dimethylformamide, N-methyl-2-pyrrolidone, and the like. Two or more of these may be contained.

[0105] The scintillator layer is preferably formed by heating and drying a coating film of a phosphor paste. Examples of the drying method include hot air drying, IR (infrared) drying, and the like. When the coating film of the phosphor paste is dried, the phosphor paste is heated, and the viscosity of the phosphor paste is reduced. Therefore, sedimentation of the phosphor, which is a material with a relatively high specific gravity in the phosphor paste, is promoted, and the packing density of the phosphor in the scintillator layer can be increased. The heating and drying method of the coating film of the phosphor paste preferably has a first step of reducing the amount of residual organic solvent in the coating film of the phosphor paste to less than 40% and a second step of reducing the amount of residual organic solvent in the phosphor paste coating film to less than 5%. The heating temperature in the first step is preferably 35 to 80°C, and the heating time is preferably 10 to 30 minutes. The heating temperature in the second step is preferably 35 to 120°C, and the heating time is preferably 120 to 800 minutes.

[0106] (Radiation detector) The radiation detector of the present invention includes the aforementioned scintillator panel on an output substrate having a photoelectric conversion layer. The output substrate has a photoelectric conversion layer and an output layer on the substrate. As the photoelectric conversion layer, one formed by forming pixels having photosensors is common.

[0107] (Line camera) The line camera of the present invention includes the aforementioned scintillator panel on a one-dimensional linear output substrate having a photoelectric conversion layer. The output substrate has a photoelectric conversion layer and an output layer on the substrate. As the photoelectric conversion layer, one formed by forming pixels having photosensors is common.

[0108] (Radiation inspection device) The radiation inspection apparatus of the present invention includes a radiation generation unit that generates radiation and the aforementioned radiation detector. The radiation inspection apparatus irradiates radiation from the radiation generation unit onto a subject and detects the radiation that has passed through the subject using the radiation detector. By mounting the radiation detector of the present invention on the radiation detection unit, a high-brightness radiation inspection apparatus can be obtained. The radiation inspection apparatus of the present invention may be used in place of the aforementioned radiation detector with the aforementioned line camera.

[0109] The radiation detection apparatus of the present invention is preferably used for industrial applications. In industrial applications, since the radiation detector is irradiated with high-energy radiation continuously for a long time, the radiation dose received by the radiation detection apparatus becomes extremely large compared to medical applications. The radiation dose to the scintillator panel provided inside the radiation detection apparatus also becomes extremely large, and the influence of luminance degradation is significant. By mounting the radiation detector of the present invention in these applications, a high-brightness radiation inspection apparatus with suppressed luminance degradation can be obtained. Here, the "industrial application" in the present invention means an application that does not directly irradiate radiation to the human body, and the "medical application" means an application that directly irradiates radiation to the human body, meaning an application for medical purposes.

[0110] (Inline inspection method) The inline inspection method of the present invention uses the aforementioned radiation inspection apparatus. The inline inspection method is a method of non-destructively and continuously inspecting a subject on a production line for electronic components, food, etc., and the radiation inspection apparatus continuously irradiates the mounted radiation detector with radiation for a long time. By using the radiation detector of the present invention in the radiation inspection apparatus, an inline inspection method capable of suppressing luminance degradation can be obtained under an environment of continuous radiation irradiation.

[0111] (Offline inspection) The offline inspection method of the present invention uses the aforementioned radiation inspection apparatus. The offline inspection method is a method of inspecting a subject nondestructively and discontinuously in the inspection of aircraft members, infrastructure facilities, etc. In the offline inspection method, for the inspection of the internal structure of the subject, it is preferable that the tube voltage in the radiation irradiation unit mounted on the radiation inspection apparatus is high. For example, it is preferably 70 kV or more. When the tube voltage is 70 kV or more, the amount of radiation passing through the subject is high, and the amount of radiation that can be detected by the radiation detector becomes a sufficient amount, so that a high-luminance radiation image can be obtained. By using the radiation detector of the present invention in the radiation inspection apparatus, an offline inspection method capable of suppressing luminance degradation can be obtained in an environment of high tube voltage radiation irradiation.

Examples

[0112] Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, the present invention is not limited thereto, nor is it construed as being limited to these examples.

[0113] The materials used in each Example and Comparative Example are shown below. Also, the characteristics of each material were measured by the following methods.

[0114] (Average particle diameter of phosphor) The phosphor was put into a sample chamber filled with water of a particle size distribution measuring device (MT3300; manufactured by Nikkiso Co., Ltd.), ultrasonic treatment was performed for 300 seconds, and then the particle size distribution was measured. The particle diameter at 50% with respect to the cumulative distribution was defined as the average particle diameter.

[0115] (Glass transition temperature of binder resin) About 10 mg of the binder resin was weighed, and using an aluminum pan and a pan cover, a temperature profile when the temperature was raised from 20 °C at a rate of 10 °C / min in a nitrogen atmosphere was measured with a differential thermal analyzer (differential type differential thermal balance TG8120; manufactured by Rigaku Corporation), and the glass transition temperature was calculated.

[0116] (Weight average molecular weight (Mw) and number average molecular weight (Mn) of binder resin) A resin solution was prepared by dissolving 2.5 mg of the binder resin in 5 mL of tetrahydrofuran. Using gel permeation chromatography GPC (GPC-22) and a differential refractive index detector RI (manufactured by Tosoh Corporation, RI-8020 type), Mw and Mn were measured when monodisperse polystyrene (manufactured by Tosoh Corporation) was used as the standard substance. The columns of GPC used were those obtained by connecting two TSKgel GMHxl (manufactured by Tosoh Corporation) and one G2500Hxl (manufactured by Tosoh Corporation), and a tetrahydrofuran solvent was passed through at a flow rate of 1.0 mL / min.

[0117] (Transmittance of the binder resin solution) A resin solution was prepared by dissolving 0.25 mg of the binder resin in 9.75 mg of the solvent described in Table 1. With the solution placed in a quartz cell with an optical path length of 1 cm, the transmittance was measured at 300 to 800 nm using an ultraviolet-visible spectrophotometer (manufactured by Hitachi High-Tech Corporation, U-4000). The baseline of each resin solution was corrected with the transmittance of the solvent alone.

[0118] (Eg of the binder resin) The binder resin and the solvent in the combination shown in Table 1 were placed in a stirring container to a concentration of 5% by weight, and heated and stirred at 60 °C for 8 hours using an oil bath to prepare a binder resin solution. The binder resin solution was spin-coated onto an 8-inch silicon wafer using a spin coater (MS-B150: manufactured by Mikasa Corporation), and baked on a hot plate at 100 °C for 5 minutes to prepare a dry film with a film thickness of 700 nm. The attenuation coefficient for 300 to 800 nm of the dry film was measured using a spectroscopic ellipsometer (FE-5000; manufactured by Otsuka Electronics Co., Ltd.), and Eg was calculated from the Tauc plot.

[0119] (Raw materials of the phosphor paste) Phosphor powder 1: Gd2O2S:Tb (manufactured by Nichia Chemical Industries, Ltd.: average particle size 11 μm) Phosphor powder 2: Gd2O2S:Pr (manufactured by Nichia Chemical Industries, Ltd.: average particle size 5 μm).

[0120] Binder resin 1: "Vylon" (registered trademark) 103 (Number of constituent atoms of π-conjugated structure: 10, corresponding to general formula (1), X 1 : Organic group derived from ethylene glycol / neopentyl glycol, Y 1 : Carbonyl group, Ar: Phenylene group, Glass transition temperature: 47 °C, Weight average molecular weight: 23,000, Polyester resin, Eg = 3.9, Amorphous) (manufactured by Toyobo Co., Ltd.) Binder resin 2: "Vylon" (registered trademark) 270 (Number of constituent atoms of π-conjugated structure: 10, corresponding to general formula (1), X 1 : Organic group derived from ethylene glycol / neopentyl glycol, Y 1 : Carbonyl group, Ar: Phenylene group, Glass transition temperature: 67 °C, Weight average molecular weight: 23,000, Polyester resin, Eg = 3.9, Amorphous) (manufactured by Toyobo Co., Ltd.) Binder resin 3: "U Polymer" (registered trademark) D type (Number of constituent atoms of π-conjugated structure: 10, corresponding to general formula (1), X 1 : Organic group derived from bisphenol A, Y 1 : Carbonyl group, Ar: Phenylene group, Glass transition temperature: 193 °C, Weight average molecular weight: 60,000, Polyarylate resin, Eg = 3.5, Amorphous) (manufactured by Unitika Ltd.) Binder resin 4: "Grilamid" (registered trademark) TR55 (Number of constituent atoms of π-conjugated structure: 10, corresponding to general formula (1), X 1 : Organic group derived from 4,4'-diamino-3,3'-dimethyldicyclohexylmethane, Y 1 : Carbonyl group, Ar: Phenylene group, Glass transition temperature: 160 °C, Weight average molecular weight: 18,000, Polyamide resin, Eg = 4.1, Amorphous) (manufactured by EMS Chemie Japan Co., Ltd.) Binder resin 5: "Bimax" (registered trademark) HR-15ET (Number of constituent atoms of π-conjugated structure: 10, corresponding to general formula (2), X 2 : Organic group derived from diphenyl ether, t = 1, Y 2 : Amide group, Ar: Group derived from phenyl group, Glass transition temperature: 260 °C, Weight average molecular weight: 8,000, Polyamideimide resin, Eg = 3.5, Amorphous) (manufactured by Toyobo Co., Ltd.) Binder resin 6: "Esrec" (registered trademark) BL-1 (number of constituent atoms of π-conjugated structure: 0, not applicable to general formulas (1) and (2), glass transition temperature: 70 °C, weight average molecular weight: 19,000, butyral resin, Eg = 3.6, amorphous) (manufactured by Sekisui Chemical Co., Ltd.) Binder resin 7: "Vylon" (registered trademark) 630 (number of constituent atoms of π-conjugated structure: 10, applicable to general formula (1), X 1 : organic group derived from ethylene glycol / neopentyl glycol, Y 1 : carbonyl group, Ar: phenylene group, glass transition temperature: 7 °C, weight average molecular weight: 23,000, polyester resin, Eg = 3.9, amorphous) (manufactured by Toyobo Co., Ltd.) Binder resin 8: "Iupilon" (registered trademark) H-4000 (number of constituent atoms of π-conjugated structure: 6, not applicable to general formulas (1) and (2), glass transition temperature: 146 °C, weight average molecular weight: 30,000, polycarbonate resin, Eg = 4.4, amorphous) (manufactured by Mitsubishi Engineering-Plastics Corporation) Binder resin 9: "Parapet" (registered trademark) GH-S (number of constituent atoms of π-conjugated structure: 0, not applicable to general formulas (1) and (2), glass transition temperature: 104 °C, weight average molecular weight: 81,000, acrylic resin, Eg = 4.7, amorphous) (manufactured by Kuraray Co., Ltd.) Binder resin 10: styrene polymer (number of constituent atoms of π-conjugated structure: 6, not applicable to general formulas (1) and (2), glass transition temperature: 100 °C, weight average molecular weight: 200,000, polystyrene, Eg = 4.4, amorphous) (manufactured by Fujifilm Wako Pure Chemical Corporation).

[0121] (Preparation of binder resin solution) Each binder resin and solvent were placed in a stirring container so as to be in the ratios shown in Table 1, and heated and stirred at 60 °C for 8 hours using an oil bath to obtain binder resin solutions 1 to 10.

[0122] (Raw materials for glass powder-containing paste) Photosensitive monomer M-1: trimethylolpropane triacrylate Photosensitive monomer M-2: tetrapropylene glycol dimethacrylate Photosensitive Polymer 1: A copolymer consisting of methacrylic acid / methyl methacrylate / styrene = 40 / 40 / 30 by mass ratio, to which 0.4 equivalents of glycidyl methacrylate was added to the carboxyl groups (weight average molecular weight 43000; acid value 100) Photoinitiator 1: 2-Benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1 (manufactured by BASF) Polymerization inhibitor 1: 1,6-Hexanediol-bis[(3,5-di-t-butyl-4-hydroxyphenyl)propionate]) Ultraviolet absorber solution 1: A 0.3 mass% solution of Sudan IV (manufactured by Tokyo Ohka Kogyo Co., Ltd.) in γ-butyrolactone Viscosity modifier 1: "Flowon" (registered trademark) EC121 (manufactured by Kyoeisha Chemical Co., Ltd.) Solvent 1: γ-Butyrolactone Low softening point glass powder 1: SiO2 27 mass%, B2O3 31 mass%, ZnO 6 mass%, Li2O 7 mass%, MgO 2 mass%, CaO 2 mass%, BaO 2 mass%, Al2O3 23 mass%, refractive index (ng) 1.56, glass softening temperature 588 °C, thermal expansion coefficient 70×10 -7 (K -1 ) and average particle diameter 2.3 μm.

[0123] (Preparation of glass powder-containing paste) 4 parts by mass of photosensitive monomer M-1, 6 parts by mass of photosensitive monomer M-2, 24 parts by mass of photosensitive polymer 1, 6 parts by mass of photoinitiator 1, 0.2 parts by mass of polymerization inhibitor 1 and 12.8 parts by mass of ultraviolet absorber solution 1 were added to 38 parts by mass of solvent 2 and heated and dissolved at 80 °C. After cooling the obtained solution, 9 parts by mass of viscosity modifier 1 was added to obtain organic solution 1. To 50 parts by mass of organic solution 1, 50 parts by mass of the low softening point glass powder was added, and then kneaded with a three-roll kneader to obtain glass powder-containing paste 1.

[0124] (Evaluation of decay time of luminescence intensity) For the scintillator panels fabricated in each of the examples and comparative examples, X-ray irradiation was performed at a tube voltage of 70 kVp, and the time change in the amount of light emission was measured using a device composed of an optical fiber (PLG-1-3000-8R (manufactured by Nippon Photonics Co., Ltd.)), a photodiode (S2281-01 (manufactured by Hamamatsu Photonics K.K.)), and a photo sensor amplifier (C9329 (manufactured by Hamamatsu Photonics K.K.)). Subsequently, the time required for the light emission intensity to reach 1 / e with respect to the light emission intensity at the time when the X-ray irradiation was stopped was calculated.

[0125] (Brightness L * , chromaticity a * , b * evaluation) For the scintillator panels fabricated in each of the examples and comparative examples, a spectrocolorimeter CM-2600D (manufactured by Konica Minolta, Inc.) was installed on the surface of the scintillator layer, and the brightness L * , chromaticity a * , b * in the range of 400 to 700 nm were measured by the SCI method.

[0126] (Luminance evaluation) The scintillator panels fabricated in each of the examples and comparative examples were installed on a commercially available FPD (Paxscan2520V (manufactured by Varian)) to fabricate an X-ray detector. Radiation with a tube voltage of 70 kVp was irradiated from the substrate side of the scintillator panel, and the luminance of the scintillator panel was detected by the FPD. The luminance was calculated from the digital value of the image with respect to the set incident radiation dose. For Examples 1 to 7 and Comparative Examples 1 to 7, the luminance of Comparative Example 1 was set as 100%, for Examples 8 to 11 and Comparative Examples 8 to 9, the luminance of Comparative Example 8 was set as 100%, for Examples 12 to 16 and Comparative Examples 10 to 14, the luminance of Comparative Example 10 was set as 100%, and for Examples 17 to 19 and Comparative Examples 15 to 16, the luminance of Comparative Example 15 was set as 100%, and relative comparisons were made respectively.

[0127] (Evaluation of luminance degradation by continuous radiation irradiation) For the scintillator panels fabricated in each of the examples and comparative examples, radiation was continuously irradiated for 14 days under the condition that the dose rate was 3 kGy / h. After irradiation, an X-ray detector was fabricated from the scintillator panel by the method described above, and the luminance of the scintillator panel was detected with an FPD. The luminance was calculated from the digital value of the image with respect to the set incident dose. Taking the luminance before continuous radiation irradiation in each of the examples and comparative examples as 100%, the relative value of the luminance after irradiation was calculated.

[0128] (Adhesion strength between the support of the scintillator layer) An adhesive tape with an adhesive strength of 5 N / 25 mm was attached to the scintillator layer of the scintillator panels fabricated in each of the examples and comparative examples, and the tape was peeled off while maintaining a peeling angle of 90°. The presence or absence of chipping, cracking, or peeling of the scintillator layer from the support was observed. This test was repeated 50 times, and the maximum number of test times in which no chipping, cracking, or peeling was observed in the scintillator layer was taken as the adhesion strength. Those in which no chipping, cracking, or peeling was observed in the scintillator layer even after 20 peelings were evaluated as A, those in which no peeling of the scintillator layer was observed up to 20 peelings were evaluated as B, and those in which peeling of the scintillator layer was observed up to 5 peelings were evaluated as C.

[0129] (Evaluation of adhesion strength degradation due to continuous radiation irradiation) For the scintillator panels fabricated in each of the examples and comparative examples, radiation was continuously irradiated for 14 days under the condition that the dose rate was 3 kGy / h. After irradiation, the adhesion strength between the scintillator layer and the support of the scintillator panel was evaluated by the method described above.

[0130] (Example 1) Each raw material was added to a stirring container at the ratios shown in Table 2 and mixed, and using a planetary stirring and degassing device (“Mazer Star” (registered trademark) KK - 400; manufactured by Kurashiki Boseki Co., Ltd.), stirring and degassing were performed at a rotation speed of 1000 rpm for 20 minutes to obtain a phosphor paste A - 1. The obtained phosphor paste 1 was applied to a substrate E20 (white PET film; manufactured by Toray Industries, Inc.) using a die coater so that the film thickness after drying would be 200 μm, and heat-dried at 70°C for 180 minutes to obtain a scintillator panel with a scintillator layer formed on the substrate.

[0131] (Examples 2 to 11, Comparative Examples 1 to 9) A scintillator panel was obtained in the same manner as in Example 1, except that the phosphor paste described in Tables 2 to 4 was used instead of the phosphor paste A-1.

[0132] (Example 12) (Fabrication of Partition Walls on Substrate) As the substrate, a soda glass plate of 125 mm × 125 mm × 0.7 mm was used. On the surface of the substrate, the glass powder-containing paste 1 was applied with a die coater so that the thickness after drying became 220 μm, and then dried to obtain a coating film of the glass powder-containing paste 1. Next, through a photomask having openings corresponding to a desired pattern (a chromium mask having lattice-shaped openings with a pitch of 127 μm and a line width of 15 μm), the coating film of the glass powder-containing paste 1 was exposed using an ultra-high pressure mercury lamp at an exposure dose of 300 mJ / cm 2 . The exposed coating film was developed in an aqueous ethanolamine solution of 0.5 mass%, and the unexposed portions were removed to obtain a lattice-shaped pattern. The obtained lattice-shaped pattern was fired at 580 °C in air for 15 minutes to form lattice-shaped partition walls mainly composed of glass.

[0133] (Formation of Reflective Layer) Using a commercially available sputtering apparatus and a sputtering target, a metal film as a reflective layer was formed on the substrate on which the above partition walls were formed. The thickness of the metal film was adjusted by arranging a glass flat plate near the substrate on which the partition walls were formed and performing sputtering under the condition that the thickness of the metal film on the glass flat plate became 300 nm. As the sputtering target, APC (manufactured by Furuya Metal Co., Ltd.), which is a silver alloy containing palladium and copper, was used. After forming the metal reflective layer, in the same vacuum batch, SiN was formed as a protective layer on the glass substrate so that the thickness became 100 nm.

[0134] (Formation of Organic Protective Layer) As 1 part by mass of "CYTOP" (registered trademark) CTL-809M (manufactured by AGC Inc.) as an amorphous fluorine-containing resin, 1 part by mass of a fluorine-based solvent CT-SOLV180 (manufactured by AGC Inc.) was mixed as a solvent to prepare a resin solution.

[0135] This resin solution was vacuum-printed on a partition substrate having a metal reflective layer and an inorganic protective layer, dried at 90 °C for 1 h, and further cured at 190 °C for 1 h to form an organic protective layer. The partition cross-section was exposed using a triple ion milling device EMTIC3X (manufactured by LEICA), and imaged and measured with a field emission scanning electron microscope (FE-SEM) Merlin (manufactured by Carl Zeiss Inc.). The thickness of the organic protective layer on the side surface of the central part in the height direction of the partition on the partition substrate was 1 μm.

[0136] A phosphor paste A-11 was prepared in the same manner as in Example 1. The obtained phosphor paste A-11 was filled into a partition substrate with a reflective layer by vacuum printing, dried at 150 °C for 30 minutes, and a scintillator panel in which a scintillator layer was formed inside the partition was obtained.

[0137] (Examples 13 to 19, Comparative Examples 10 to 16) A scintillator panel was obtained in the same manner as in Example 12, except that the phosphor pastes described in Tables 5 to 6 were used instead of the phosphor paste A-11.

[0138] The configurations and results of each example and comparative example are shown in Tables 2 to 6.

[0139]

Table 1

[0140]

Table 2

[0141]

Table 3

[0142]

Table 4

[0143]

Table 5

[0144]

Table 6

Explanation of Symbols

[0145] 1 X-ray detector 2 Scintillator panel 3 Output substrate 4 Scintillator layer 5 Substrate 6 Phosphor 7 Binder resin 8 Diaphragm layer 9 Photoelectric conversion layer 10 Output layer 11 Substrate 12 Power supply unit 13 Partition wall

Claims

1. A line camera provided with a scintillator panel on an output substrate having a photoelectric conversion layer, wherein the scintillator panel is a scintillator panel having a base material and a scintillator layer containing a phosphor, and the scintillator layer contains a binder resin having a π-conjugated structure composed of 7 or more atoms. The binder resin has a structure represented by the following general formula (1) or (2) in the main chain. 【Chemical formula 1】 (In the above general formulas (1) and (2), X1, X2, Y1 and Y2 each independently represent a divalent organic group. Ar represents an aromatic hydrocarbon group. t represents an integer of 1 or 2.) And the glass transition point of the binder resin is 30 to 430 ° C., and the film thickness of the scintillator layer is 50 to 800 μm.

2. The line camera according to claim 1, wherein the binder resin has a π-conjugated structure composed of 30 or fewer atoms.

3. The line camera according to claim 1 or 2, wherein the transmittance of a solution containing 2.5% by weight of the binder resin at an optical path length of 1 cm and a wavelength of 400 nm is 85% or more.

4. The line camera according to any one of claims 1 to 3, wherein the energy level difference Eg between the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the binder resin is 2.0 eV or more and 4.2 eV or less.

5. The line camera according to any one of claims 1 to 4, wherein the weight average molecular weight of the binder resin is in the range of 5,000 to 100,000.

6. The line camera according to any one of claims 1 to 5, wherein the volume ratio of the phosphor to the binder resin in the scintillator layer is phosphor: binder resin = 80:20 to 95:

5.

7. The line camera according to any one of claims 1 to 6, wherein the phosphor contains gadolinium oxysulfide.

8. The line camera according to any one of claims 1 to 7, wherein the time for the phosphor to reach a light emission intensity of 1 / e times the initial light emission intensity is 100 μs or less.

9. The line camera according to any one of claims 1 to 8, having a partition wall that partitions the scintillator layer.

10. A radiation inspection apparatus including the line camera according to any one of claims 1 to 9.

11. The radiation inspection apparatus according to claim 10, which is used for industrial applications.

12. An in-line inspection method using the radiation inspection apparatus according to claim 10 or 11.

13. An off-line inspection method using the radiation inspection apparatus according to claim 10 or 11, wherein the tube voltage during radiation irradiation is 70 kV or more.

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