JP5896113B2 - Manufacturing method of radiation shielding article - Google Patents

Description

  The present invention relates to a radiation shielding article for shielding radiation.

  Radiation shielding articles consisting of radiation shielding glass plates with a thickness of 5 mm to 500 mm are used for storage of spent nuclear fuel, nuclear facilities such as processing facilities, medical facilities using medical equipment such as CT scans and X-rays, X-ray diffraction devices, It is used as a window glass for observation in research facilities that use measurement devices such as particle accelerators. It is also used as a window glass for heavy machinery such as forklifts and cranes used for processing spent nuclear fuel.

  The radiation shielding glass plate constituting this radiation shielding article has a different thickness depending on the application, and when used in nuclear facilities or heavy machinery where the radiation dose is large compared to medical facilities, the radiation shielding ability In order to increase the thickness, a thick radiation shielding glass plate, specifically, a radiation shielding glass plate having a thickness of 200 mm or more is used. Such a radiation shielding glass plate having a thickness of 200 mm or more is produced by a so-called casting method in which molten glass is poured into a mold and slowly cooled in the mold.

  The radiation shielding glass plate produced by the casting method is much thicker than ordinary window glass, so it may be damaged by thermal stress if it is not cooled very slowly, so it takes several months to cool to room temperature. It takes a period of Thus, since a slow cooling period is long, a radiation shielding glass plate cannot be produced in large quantities in a short time. Therefore, as disclosed in Patent Document 1, it has been attempted to produce a radiation shielding article having a thickness of 200 mm or more by laminating a plurality of plate glasses having radiation shielding ability with a resin film.

JP 2003-315490 A

  The radiation shielding glass plate and the resin film are colored brown although there is a difference in degree when irradiated with radiation. When the radiation shielding glass plate and the resin film are colored brown, the visibility when the object is observed through the radiation shielding article is lowered.

  Moreover, depending on the kind of resin film, resin is foamed and bubbles are generated when irradiated with radiation, or the adhesive force with the radiation shielding glass plate is reduced. The radiation shielding glass plate is not collapsed because it is fixed to the metal frame, but there is a slight gap between the radiation shielding glass plate and the resin film. There is a possibility that visibility may be reduced due to scattering of light.

  In the present invention, even when a large amount of radiation is irradiated, the resin film is colored brown, the resin film is not fired, no interference fringes are generated, the visibility is good, and the slow cooling time is shortened for a short period of time. It is an object of the present invention to provide a radiation shielding article that can be produced in a large amount and is less likely to cause separation of radiation shielding glass plates.

  The present inventors use a two-component resin prepared by mixing a main agent and a curing agent as a resin used when bonding a radiation shielding glass plate, and the content of sulfur contained in the resin. It has been found that by making the amount smaller than that of the conventional resin, it is possible to suppress the resin from being colored brown by irradiation with a large amount of radiation.

That is, the radiation shielding article of the present invention is a radiation shielding article obtained by laminating a plurality of radiation shielding glass plates having radiation shielding ability by laminating them with a resin, and the resin includes gamma rays having ⁶⁰ Co as a radiation source. Is irradiated with 10000 Gy at an integrated dose, and the Y value per 1 mm thickness is 30 or more.

  The resin constituting the radiation shielding article of the present invention is characterized in that the Y value per 1 mm thickness is 50 or more.

  The resin constituting the radiation shielding article of the present invention has a Y value of 30 or more per 1 mm thickness after being irradiated with ultraviolet rays irradiated from a 400 W mercury lamp at a position 20 cm from the irradiation source for 3 hours. It is characterized by being.

  The resin constituting the radiation shielding article of the present invention is a two-component resin that is cured by mixing an epoxy resin main agent and a thiol-based curing agent, and the main agent and the curing agent The mixing ratio (mass of main ingredient: mass of curing agent) is 1.5: 1.0 to 9.0: 1.0.

The radiation shielding article of the present invention is characterized in that the Y value per 30 mm thickness after irradiation with 10000 Gy of gamma rays with ⁶⁰ Co as a radiation source is 70 or more.

  The radiation shielding article of the present invention is characterized in that the Y value per 30 mm thickness is 80 or more.

  The radiation shielding article of the present invention is characterized in that a Y value per 30 mm thickness after irradiation with ultraviolet rays irradiated from a 400 W mercury lamp at a position 20 cm from an irradiation source for 3 hours is 70 or more. To do.

  Even when a large amount of radiation is irradiated, a resin that is difficult to be colored brown is used, so even if the radiation is irradiated for a long time, the Y value is high, that is, the visibility is good and can be used for a long period of time. A radiation shielding article can be provided. Moreover, since the radiation shielding article according to the present invention is formed by laminating a plurality of radiation shielding glass plates, the radiation shielding glass plate constituting the radiation shielding article is thinner than the conventional one, and the time required for slow cooling is short. Thus, the radiation shielding article can be produced in a short time. In addition, since the resin constituting the radiation shielding article according to the present invention is less likely to deteriorate the adhesiveness even when irradiated with radiation for a long time, the radiation shielding glass plates are difficult to peel off.

It is sectional drawing of the radiation shielding article of this embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described. However, the present invention is not limited to the following embodiments, and is based on ordinary knowledge of a person skilled in the art without departing from the gist of the present invention. It should be understood that modifications and improvements as appropriate to the following embodiments also fall within the scope of the present invention.

  As shown in the sectional view of FIG. 1, the radiation shielding article 10 of the present invention is configured by attaching a plurality of radiation shielding plate glasses 2 with a resin layer 1 interposed therebetween. In FIG. 1, the radiation shielding article 10 by which five radiation shielding glass plates are shown as an example.

  The resin layer 1 is adhesive in order to adhere a plurality of radiation shielding glass plates 2 and is adhered substantially uniformly to the main surface of the radiation shielding glass plate 2, that is, the adhesion surface. It becomes. The resin layer 1 has adhesiveness, and the radiation shielding glass plates 2 can be firmly bonded to each other by being bonded substantially uniformly to the bonding surface. The thickness of the resin layer 1 is preferably 1 to 100 μm. If the thickness of the resin layer 1 is less than 1 μm, the adhesive strength of the resin layer 1 is reduced, and the radiation shielding glass plate 2 may be peeled off, which is not preferable. On the other hand, when the thickness of the resin layer 1 is larger than 100 μm, it is not preferable because when the radiation shielding glass plates 2 are bonded to each other, it takes time until the resin layer 1 is fixed, and the bonding workability is lowered. . Moreover, since there exists a possibility that visibility may fall with the resin layer 1, it is not preferable.

Further, the resin layer 1 has a Y value of 30 or more after 1 mm of thickness is irradiated with 10000 Gy of gamma rays using ⁶⁰ Co as a radiation source at an integrated dose. The Y value in the present invention was calculated based on JISZ 8722. Specifically, it is a value calculated from the result of measuring the transmittance in the wavelength range of 200 to 800 nm using a spectrophotometer. The Y value per 1 mm thickness may be a value measured directly from the transmittance of a resin layer having a thickness of 1 mm, or the transmittance measured by preparing a resin layer other than 1 mm. The Y value may be calculated from the transmittance converted to absorbance and converted to a thickness of 1 mm based on Lambert Beer's law.

Since the resin layer 1 is colored brown when irradiated with radiation such as gamma rays, the visibility of the radiation shielding article 10 is lowered by irradiation with radiation for a long time, and observation and work become difficult. There is a fear. ^Since the Y value per 1 mm thickness after irradiation with 10000 Gy of gamma rays with ⁶⁰ Co as the radiation source is 30 or more, the visibility that enables observation and work for a long time can be ensured. In view of observation and workability, the resin layer 1 after gamma ray irradiation using ⁶⁰ Co as a radiation source preferably has a Y value of 35 or more per 1 mm thickness.

The resin layer 1 preferably has a Y value of 50 or more per 1 mm thickness. In addition, the Y value per 1 mm thickness here represents the Y value before irradiating gamma rays with ⁶⁰ Co as a radiation source and ultraviolet rays described later. It is preferable that the Y value per 1 mm thickness is 50 or more because the visibility of the radiation shielding article 10 at the initial stage of use becomes good. The Y value per 1 mm thickness may be a value directly measured from the transmittance of the resin layer having a thickness of 1 mm, similarly to the Y value after irradiation with gamma rays using ⁶⁰ Co as a radiation source. The Y value may be calculated from the transmittance converted to a thickness of 1 mm based on Beer's law. In consideration of the visibility of an observer or an operator, the resin layer 1 preferably has a Y value of 55 or more per 1 mm thickness.

  When the radiation shielding article 10 is used as a window glass of heavy equipment frequently used outdoors, the radiation shielding article 10 is irradiated with sunlight, and the resin layer 1 may be colored brown by ultraviolet rays contained in the sunlight. Therefore, the radiation shielding article 10 is also colored by being irradiated with ultraviolet rays over a long period of time.

Further, the resin layer 1 preferably has a Y value of 30 or more after being irradiated with ultraviolet rays irradiated from a 400 W mercury lamp at a position 20 cm from the irradiation source for 3 hours. When the Y value per 1 mm thickness after irradiation with ultraviolet rays is 30 or more, even if the radiation shielding article 10 is irradiated with sunlight for a long time, visibility that enables observation and work can be secured. The Y value per 1 mm thickness may be a value directly measured from the transmittance of the resin layer having a thickness of 1 mm, similarly to the Y value after irradiation with gamma rays using ⁶⁰ Co as a radiation source. The Y value may be calculated from the transmittance converted to a thickness of 1 mm based on Beer's law. In view of observation and workability, the resin layer 1 preferably has a Y value of 33 or more per 1 mm thickness. The rated voltage of the 400 W mercury lamp can be arbitrarily selected, for example, 100 V, 110 V, 120 V, 200 V, etc., and is preferably 100 V, which is easily available.

  Examples of the resin layer 1 include a two-component resin that is cured by mixing an epoxy fat-based main agent and a thiol-based curing agent, and the mixing ratio of the main agent and the curing agent is set to a predetermined ratio. It is specified. The two-component resin refers to a resin having adhesiveness by curing the polymer resin as the main agent by mixing the main agent and the curing agent. By mixing the main agent and the curing agent, radiation shielding. It becomes possible to stick the glass plates 2 together. Moreover, since the epoxy resin is used, the adhesiveness with the radiation shielding glass plate 2 is high, the occurrence of interference fringes due to peeling can be suppressed, and the foaming of the resin hardly occurs.

The resin layer 1 has good visibility and is used over a long period of time because the Y value before and after irradiation with ⁶⁰ Co as a radiation source and ultraviolet rays is ⁶⁰ % or more. It is possible to provide the radiation shielding article 10 that can be used. As a result of intensive studies, the inventors of the present invention, as a result of the resin layer 1 exhibiting a color due to the sulfur content in the curing agent, that is, the thiol group, and being irradiated with radiation such as gamma rays or ultraviolet rays. It was found to be colored brown. The thiol group forms radicals such as thiyl radicals when irradiated with radiation or ultraviolet rays. A radical withdraws an atom such as hydrogen from the allylic position of the polymer resin to form a conjugated unsaturated bond. When a conjugated unsaturated bond is formed, the absorption edge of light shifts from the ultraviolet region to the visible light region, so that the resin is colored brown. Therefore, the sulfur content in the resin layer 1 is suppressed by setting the mixing ratio of the main agent and the curing agent (mass of the main agent: mass of the curing agent) within a predetermined range. As a result, it is possible to suppress the formation of a conjugated unsaturated bond due to radicals and to produce the radiation shielding article 10 with good visibility. Moreover, since it can suppress that a conjugated unsaturated bond is formed, a possibility that the adhesive force of the resin layer 1 may fall falls.

  The mixing ratio of the main agent and the curing agent (the mass of the main agent: the mass of the curing agent) is preferably 1.5: 1.0 to 9.0: 1.0. When the mixing ratio is less than 1.5: 1.0, the resin layer 1 is colored brown, and may be colored brown when irradiated with radiation or ultraviolet rays. On the other hand, if the mixing ratio is greater than 9.0: 1.0, the main agent becomes difficult to cure when the main agent and the curing agent are mixed, and the resin does not solidify over a long period of time. This is not preferable because the property may be deteriorated. A more preferable mixing ratio is 2.5: 1.0 to 7.0: 1.0.

  Examples of the thiol-based curing agent of the present invention include 1,3-butanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4- Benzenedithiol, 1,10-decanedithiol, 1,2-ethanedithiol, 1,6-hexanedithiol, 1,9-nonanedithiol, 1,8-octanedithiol, 1,5-pentanedithiol, 1,2-propane Dithiol, 1,3-propadithiol, toluene-3,4-dithiol, 3,6-dichloro-1,2-benzenedithiol, 1,3,5-triazine-2,4,6-trithiol (trimercapto-triazine) ), 1,5-naphthalenedithiol, 1,2-benzenedimethanethiol, 1,3-benzenedimethanethiol 1,4-benzenedimethanethiol, 4,4′-thiobisbenzenethiol, 2-di-n-butylamino-4,6-dimercapto-s-triazine, trimethylolpropane tris (β-thiopropionate) ), 2,5-dimercapto-1,3,4-thiadiazole, 1,8-dimercapto-3,6-dioxaoctane, 1,5-dimercapto-3-thiapentane and the like, and polythiol (trade name: Thiocol) And thiol compounds such as polythiol such as LP70 (manufactured by Toraythiol Co., Ltd.). In addition, these can be used alone or in combination of two or more.

  As the main component of the epoxy-based resin, an acrylic resin or a styrene resin can be used in combination even if the epoxy resin is used alone. In the main component of the polymer resin, if the main chain contains a sulfur atom or a nitrogen atom, the bond is broken by irradiation with radiation, and the electron moves, so that it is easily colored brown. This is not preferable because of fear.

  The radiation shielding glass plate 2 of the present invention is glass capable of suppressing transmission of radiation such as gamma rays and X-rays. Generally, the radiation shielding glass plate 2 contains lead for the purpose of shielding radiation. The radiation shielding ability generally increases as the lead content and the thickness of the radiation shielding glass plate 2 increase. However, as described above, as the thickness of the radiation shielding glass plate 2 increases, a slow cooling operation in the production of the radiation shielding glass plate 2 requires a long time, so that the radiation shielding glass plate 2 of the present invention is rolled out. Or a thickness of 3 to 30 mm, which can be produced by the float method. When the thickness of the radiation shielding glass plate is 30 mm or less, the annealing time of the radiation shielding glass plate 2 can be shortened. Moreover, when the thickness of the radiation shielding glass plate 2 is 3 mm or more, it is possible to produce the radiation shielding glass plate 2 that is not easily damaged by an impact, and the radiation shielding article 10 having a thickness of 200 mm or more is produced. In doing so, the number of times of bonding (number of sheets) can be reduced. In the present invention, the radiation shielding glass plate 2 per sheet is thinner than the radiation shielding glass plate used in the conventional radiation shielding article, but a plurality of radiation shielding glass plates 2 are laminated. And since the sum total of the thickness of the radiation shielding glass plate 2 is made equivalent, it becomes possible to obtain the radiation shielding article 10 which has the radiation shielding ability equivalent to the radiation shielding article with the conventional large thickness. In addition, in FIG. 1, although it is the radiation shielding article 10 which stuck the five radiation shielding glass plates 2, as long as two or more radiation shielding glass plates 2 are stuck, what number may be sufficient. . If the radiation shielding article 10 according to the present invention is used for the window glass of heavy equipment such as forklifts and cranes used to treat nuclear facilities and spent nuclear fuel, 10 or more radiation shielding glass plates are used. By sticking 2, it is preferable to make thickness 200 mm or more.

As described above, the visibility of the radiation shielding article 10 during observation and work is important. In view of using the radiation shielding article 10 for a long period of time, the radiation shielding article 10 of the present invention has a Y value per 30 mm in thickness after being irradiated with 10000 Gy of gamma rays with ⁶⁰ Co as a radiation source at an integrated dose. Is preferably 70 or more. In view of the workability of the observer and the worker, it is more preferable that the Y value per 30 mm thickness after irradiation with 10000 Gy of gamma rays using ⁶⁰ Co as a radiation source is 73 or more. The Y value per 30 mm thickness may be a value measured directly from the transmittance of a radiation shielding article having a thickness of 30 mm, or a radiation shielding article other than 30 mm may be prepared and measured. The transmittance may be converted to absorbance, and the Y value may be calculated from the transmittance converted to a thickness of 30 mm based on Lambert Beer's law.

In order to obtain such a radiation shielding article 10, as the radiation shielding glass plate 2, PbO 15 to 40%, SiO ₂ 40 to 60%, B ₂ O ₃ 0 to 10%, in mass percentage in terms of oxides, As disclosed in JP-A-2-212331, Na ₂ O 0-10%, K ₂ O 0-10%, and BaO having high radiation shielding ability instead of PbO. It is also possible to use a radiation-shielding glass plate 2 that is substantially free of lead and that blocks.

  PbO is a component for shielding radiation such as X-rays and gamma rays. Its content is 15 to 40%, preferably 20 to 39%, more preferably 25 to 38%. When the content of PbO is more than 40%, the radiation shielding glass plate 2 is tinged with a yellowish color, so that the visibility is deteriorated and there is a possibility that the material is turned brown when irradiated with radiation. On the other hand, if the content of PbO is less than 15%, the ability to shield radiation such as gamma rays may be reduced.

SiO ₂ is a component that forms a network of glass. Its content is 40-60%, preferably 43-57%, more preferably 45-55%. If the content of SiO ₂ exceeds 60%, the high-temperature viscosity of the glass increases, melting and molding become difficult, and the amount of PbO that can be contained is limited, so that gamma ray shielding ability may be reduced. . On the other hand, when the content of SiO ₂ is less than 40%, the components forming the skeleton of the glass become too small, the glass becomes structurally unstable, and the water resistance of the glass decreases.

B ₂ O ₃ is a component that lowers the high-temperature viscosity of the glass to improve the meltability and formability, and to increase the thermal stability. Its content is 0-10%, preferably 0-8%, more preferably 0.1-5%. If the content of B ₂ O ₃ is more than 10%, the water resistance of the glass may be lowered.

Na ₂ O and K ₂ O are components that lower the high-temperature viscosity of the glass and improve the meltability and moldability. The content is 0 to 10%, preferably 0 to 8%, more preferably 1 to 5%. If these contents are more than 10%, the water resistance may decrease.

  In addition, a clarifying agent and other components can be added up to 10% as long as the properties of the glass are not impaired.

Moreover, by using the radiation shielding glass plate 2 as described above, the radiation shielding article 10 having a Y value of 80 or more per 30 mm thickness can be obtained, and the visibility is improved. Note that the Y value per 30 mm thickness may be a value directly measured from the transmittance of a radiation shielding article having a thickness of 30 mm, similar to the Y value after irradiation with gamma rays using ⁶⁰ Co as a radiation source. Alternatively, the Y value may be calculated from the transmittance converted to a thickness of 30 mm based on the Lambert Beer law. In view of observation and workability, the Y value per 30 mm thickness is more preferably 83 or more.

In addition, the radiation shielding glass plate 2 as described above is not easily discolored by ultraviolet rays. Therefore, even when the sunlight is irradiated for a long time, the visibility that enables observation and work can be secured. It is possible to obtain the radiation shielding article 10 having a Y value of 70 or more per 30 mm thickness after being irradiated with ultraviolet rays to be irradiated at a position 20 cm from the irradiation source for 3 hours. The Y value per 30 mm thickness may be a value directly measured from the transmittance of a 30 mm radiation shielding article, as well as the Y value after irradiation with gamma rays using ⁶⁰ Co as a radiation source. The Y value may be calculated from the transmittance converted to a thickness of 30 mm based on Beer's law. In view of observation and workability, the Y value per 30 mm thickness is more preferably 73 or more.

  Next, a method for producing the radiation shielding article 10 of the present invention will be described.

(Production of radiation shielding glass plate)
Uniform glass is produced by melting a batch of glass raw materials in a glass melting furnace at 1000 to 1500 ° C., such as float method, rollout method, cast method, press molding method, down draw method, fusion method, etc. A radiation shielding glass body having a thickness of about 1 to 20 mm is produced by a known molding method. The radiation shielding glass plate 2 was obtained by gradually cooling the radiation shielding glass body and performing processing such as cutting and polishing.

(Production of radiation shielding articles)
First, the epoxy resin main agent and the thiol-based curing agent are sufficiently mixed so that the mass of the main agent: the mass of the curing agent is 1.5: 1.0 to 9.0: 1.0. After the defoaming, the entire main surface of the first radiation shielding glass plate 2 is uniformly covered with the mixed solution of the main agent and the curing agent, and the main surface covered with the mixed solution of the main agent and the curing agent; Then, one main surface of the second radiation shielding glass plate 2 is overlapped to form a laminated glass. Next, the entire main surface of the laminated glass or the entire one main surface of the third radiation shielding glass plate 2 is uniformly covered with the mixed liquid of the main agent and the curing agent, and the main agent and the curing agent are mixed. One main surface of the laminated glass or the third radiation shielding glass plate 2 covered with the liquid and one of the laminated glass or the third radiation shielding glass plate 2 not covered with the mixed liquid of the main agent and the curing agent Overlay the main surface. This series of operations was repeated until a desired thickness was obtained, thereby producing a laminate. After drying the laminated body having a desired thickness or curing the resin layer 1 by irradiating ultraviolet rays or the like, the radiation shielding article 10 of the present invention was obtained by cutting and polishing as necessary. In addition, as a method of uniformly covering the entire one main surface of the radiation shielding glass plate 2 with the mixed liquid of the main liquid and the curing agent, a method of superposing so as to sandwich an excessive amount of the mixed liquid that has been applied, sprayed, and poured out. From the viewpoint of workability, a method of superposing so as to sandwich an excess amount of the mixed liquid that has flowed out is preferable.

  Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

(Preparation of radiation shielding articles)
Example 1
First, six NBs (manufactured by Nippon Electric Glass Co., Ltd.) were prepared as radiation shielding glass plates. The radiation shielding glass plate has a size of height 1000 mm × width 1000 mm × thickness 12 mm, and both surfaces are mirror-polished. Cemedine # 1565 manufactured by Cemedine Co., Ltd. was used for bonding the radiation shielding glass plates. Cemedine # 1565 is an epoxy resin, and a main agent and a curing agent are a set. The curing agent is thiol-based. Next, the mixture is mixed so that the mixing ratio of the main agent and the curing agent (the mass of the main agent: the mass of the curing agent) is 4.0: 1.0, and the mixture is stirred to be homogeneous and then left to stand in a reduced pressure state. To degas. Subsequently, an excessive amount of the main agent and the curing agent was poured out on one main surface of one radiation shielding glass plate and laminated by overlapping with the second radiation shielding glass plate. An excessive amount of the mixed liquid of the main agent and the curing agent was poured out on one main surface of the overlapped radiation shielding glass plate in the same manner as described above, and was superposed on the third radiation shielding glass plate. By repeating this series of operations, a total of six radiation shielding glass plates were laminated. And the mixed liquid of a main ingredient and a hardening | curing agent was dried by standing the laminated radiation shielding glass plate, and the radiation shielding article was obtained.

(Example 2)
A radiation shielding article was obtained in the same manner as in Example 1 except that the mixing ratio of the main agent and the curing agent (the mass of the main agent: the mass of the curing agent) was 3.0: 1.0.

(Example 3)
A radiation shielding article was obtained in the same manner as in Example 1 except that the mixing ratio of the main agent and the curing agent (the mass of the main agent: the mass of the curing agent) was 2.3: 1.0.

Example 4
As the radiation shielding glass plate, three LX-35Cs (manufactured by Nippon Electric Glass Co., Ltd.) each having a height of 1000 mm, a width of 1000 mm, and a thickness of 12 mm and mirror-polished on both sides were prepared. A radiation shielding article was obtained in the same manner as in Example 1 except that LX-35 was alternately laminated.

(Example 5)
A radiation shielding article was obtained in the same manner as in Example 1 except that LX-35C having a height of 1000 mm, a width of 1000 mm, and a thickness of 12 mm was prepared as the radiation shielding glass plate, and both surfaces were mirror-polished.

(Comparative Example 1)
A radiation shielding article was obtained in the same manner as in Example 1 except that the mixing ratio of the main agent and the curing agent (the mass of the main agent: the mass of the curing agent) was 1.0: 1.0.

(Production of radiation shielding article sample)
Three test pieces of 30 mm in height x 30 mm in width x 30 mm in thickness (both surfaces parallel to the resin layer are polished to a mirror surface) from the prepared radiation shielding articles of Examples 1 to 5 and Comparative Example 1, The first was used for the gamma irradiation test, the second was used for the ultraviolet irradiation test, and the third was not irradiated with gamma rays or ultraviolet rays. In the gamma ray irradiation test, gamma rays with ⁶⁰ Co as a radiation source were irradiated with an integrated dose of 10,000 Gy. In the ultraviolet irradiation test, ultraviolet rays irradiated from a mercury lamp with a rated voltage of 100 V and 400 W were irradiated for 3 hours at a position 20 cm from the irradiation source. Note that irradiation with gamma rays and ultraviolet rays was performed from a direction perpendicular to the resin layer.

(Production of resin sample)
The resin used in the production of Examples 1 to 5 and Comparative Example 1 was Cemedine # 1565, and after degassing the mixed liquid of the main agent and the curing agent under reduced pressure, it was put in a container 30 mm long × 30 mm wide × 30 mm high. A resin sample was obtained by allowing to stand in a dark place at room temperature and solidifying. The resin sample used in Examples 1, 4, and 5 was Sample 1, the resin sample used in Example 2 was Sample 2, the resin sample used in Example 3 was Sample 3, and the resin sample used in Comparative Example 1 was Sample 4. Then, the prepared resin samples Samples 1 to 4 were cut into three, and a gamma ray irradiation test, an ultraviolet ray irradiation test, and a test piece that was not irradiated with gamma rays and ultraviolet rays were produced in the same manner as the radiation shielding article.

(Measurement of Y value)
The Y value was measured based on JISZ 8722. By measuring the transmittance at a wavelength of 200 to 800 nm of the radiation shielding articles prepared in Examples 1 to 5 and Comparative Example 1 with a spectrophotometer V-670 (manufactured by JASCO Corporation), the thickness in the radiation shielding article is The Y value per 30 mm was calculated. Further, the transmittance per 10 mm thickness is measured by measuring the Y value of the resin sample, the transmittance of 10 mm thickness is converted to absorbance, and the transmittance is converted to 1 mm thickness based on the Lambert Beer law. The Y value per 1 mm thickness was calculated from the rate.

  Table 1 shows the Y value of the radiation shielding article, and Table 2 shows the Y value of the resin sample.

DESCRIPTION OF SYMBOLS 1 Resin layer 2 Radiation shielding glass plate 10 Radiation shielding article

Claims (3)

  A plurality of radiation shielding glass plates having radiation shielding ability; ⁶⁰ After irradiating 10000 Gy of gamma rays with Co as a radiation source at an integrated dose, a resin having a Y value of 30 or more per 1 mm thickness measured based on JISZ 8722 is laminated and laminated,
⁶⁰ A method of manufacturing a radiation shielding article having a Y value of 70 or more per 30 mm thickness measured according to JISZ 8722 after irradiating gamma rays with Co as a radiation source at an accumulated dose of 10,000 Gy,
  The main component of the epoxy resin that does not contain a sulfur atom in the main chain and the thiol-based curing agent have a mixing ratio of the main agent and the curing agent (the mass of the main agent: the mass of the curing agent) of 2.5: 1. A method for producing a radiation shielding article, wherein a plurality of radiation shielding glass plates are bonded together with a two-component resin mixed so as to be 0 to 7.0: 1.0. The method for producing a radiation shielding article according to claim 1, wherein the resin has a Y value of 50 or more per 1 mm thickness. The method for producing a radiation shielding article according to claim 1, wherein the Y value per 30 mm thickness is 80 or more.