JP2012108103A - Radiation shield safety glass and radiation shield window - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation shield safety glass 10 and a radiation shield window that can protect a cover plate glass 2 at a peripheral part from being broken even if an external force is applied due to earthquake, for example.SOLUTION: Laminated glass layers are formed by sticking a cover plate glass 2 on a radiation shield plate glass 1 via a resin layer 3. In all or a part of the peripheral part of the laminated glass layers, an end surface 1a of the radiation shield plate glass 1 protrudes beyond an end surface 2a of the cover plate glass 2.

Description

  The present invention relates to a radiation shielding safety glass used in a radiation inspection of a medical facility, a nuclear facility, a hot laboratory, and the like, and a radiation shielding window using the radiation shielding safety glass.

  Generally, metallic lead, iron, or concrete is used on the walls of facilities that handle radiation, such as medical institutions, in order to shield the radiation. In that case, the equipment operation room, examination room, etc. are partitioned by concrete, etc. If it is a structure, it is necessary to install a window in the room. In addition, when an examination is performed by injecting or inhaling a drug or the like that generates radiation into the subject, the doctor, laboratory technician, nurse, or the like, for example, confirms the subject's complexion or pulse. When observing near the screen, a screen with a window is required to prevent radiation directly from the whole body.

  The characteristics required for these laboratory walls and screen windows are the ability to shield radiation from radiation sources, so-called radiation shielding capability, in order to shield radiation and ensure safety for the human body. Become. Moreover, if the state of the subject cannot be accurately visually confirmed, various adverse effects are caused, and particularly in the medical field, the examination result of the subject may be adversely affected. Necessary.

  In addition, there is a PET examination as a new examination method for diagnosing the cause and pathology of a disease by capturing the action of the heart and brain as a tomographic image with a PET-CT apparatus or the like employing “positron tomography”. In a medical environment involving this PET test, gamma rays (γ rays) are emitted in all directions from the subject to which the test drug is administered. It is an indispensable condition to shield so that there is no.

  Moreover, even in nuclear facilities, hot labs, etc. that handle radioactive materials, high visibility is not always required, but windows that shield radiation safely are required.

  Patent Document 1 discloses a fire-resistant X-ray shielding laminated glass in which an X-ray shielding glass, an expanded layer, and soda lime glass are laminated. However, since this laminated glass uses soda lime glass having a small radiation shielding ability, there is a problem that the laminated glass has to be thick and heavy in order to ensure the necessary radiation shielding ability.

  Patent Document 2 discloses a radiation shielding laminated glass in which a plurality of plate glasses essentially containing Pb and having a lead equivalent to 100 kV X-rays of 0.03 mmPb / mm or more are laminated via a resin film. It is disclosed. However, although this laminated glass is suitable for a radiation shielding window that shields low-energy radiation of 100 kV or less, there is a problem that it is not suitable for use for shielding high-energy radiation.

  Further, in Patent Document 3, as shown in FIG. 7, a radiation shielding laminate in which a cover plate glass 120 not containing Pb is laminated via a resin film 130 on a radiation shielding plate glass 110 having excellent radiation shielding ability containing Pb. Glass 100 is disclosed. In this radiation shielding laminated glass 100, since the cover plate glass 120 is more excellent in radiation shielding ability and chemical durability than soda lime glass, the radiation shielding laminated glass can be reduced in weight.

  However, the radiation shielding laminated glass 100 has a problem that the cover plate glass 120 is easily damaged at the peripheral edge when an external force is applied. For example, as shown in FIG. 8, when the radiation shielding laminated glass 100 is fixed to the frame body 140 via the setting block 150 and configured as the radiation shielding window 200, the frame body 140 is applied with an external force due to, for example, an earthquake or the like. When deformed, as shown in FIG. 9, the stress due to the external force or its own weight concentrates on the peripheral edge of the relatively thin cover plate glass 120 through the setting block 150, so that the cover plate glass 120 was easily damaged. Further, when a movable partition with a window is configured using the radiation shielding laminated glass 100, the peripheral portion of the cover plate glass 120 may be damaged due to stress concentration due to, for example, vibration when the partition is moved. .

WO2004 / 087414A2 publication JP 2003-315490 A JP 2008-286787 A

  The present invention was made in view of the above-mentioned problems in the conventional radiation shielding laminated glass. For example, even if some external force is applied due to an earthquake or the like, the cover plate glass at the peripheral edge of the laminated glass is formed. It is an object to provide a radiation shielding safety glass and a radiation shielding window capable of preventing breakage.

The present invention is a laminated glass in which a cover plate glass is bonded to a radiation shielding plate glass through a resin layer,
In the peripheral part of this laminated glass, the end surface of the said radiation shielding plate glass protrudes rather than the end surface of the said cover plate glass, It is characterized by the above-mentioned.

  In the present invention, the laminated glass has a visible light average transmittance of 75% or more, and more preferably 80% or more. Further, the total light transmittance at a wavelength of 400 nm is 10% or more, and 11% or more is practically preferable. In this case, when the radiation shielding plate glass has a thickness of 10 mm and the total light transmittance at a wavelength of 400 nm is 50% or more, it is easy to realize.

Further, the present invention is a radiation shielding window formed by fixing a laminated glass in which a cover plate glass is bonded to a radiation shielding plate glass via a resin layer to a frame body via a setting block,
In the peripheral part of the laminated glass, the end face of the radiation shielding plate glass protrudes from the end face of the cover plate glass, and there is a gap between the end surface of the cover plate glass and the setting block.

  According to the radiation shielding safety glass and the radiation shielding window according to the present invention, since the end face of the radiation shielding plate glass protrudes from the end face of the cover plate glass, a clearance is secured between the end face of the cover plate glass and the setting block of the window frame. Even if an external force due to an earthquake or the like is applied and the frame body is deformed, the external force or its own weight does not concentrate on the edge of the cover plate glass through the setting block, and the cover plate glass is prevented from being damaged. Can do.

It is sectional drawing of the radiation shielding safety glass of this embodiment. It is explanatory drawing of the radiation shielding window of this embodiment, (a) is a whole front view, (b) is S1-S1 line arrow principal part expanded sectional drawing. It is a principal part expanded sectional view at the time of a deformation | transformation of the radiation shielding window of this embodiment. It is the whole radiation shielding window front view of a modification. It is a principal part expanded sectional view of the radiation shielding safety glass of a modification. It is a principal part expanded sectional view of the radiation shielding safety glass of another modification. It is sectional drawing of the conventional radiation shielding safety glass. It is explanatory drawing of the conventional radiation shielding window, (a) is a whole front view, (b) is an S2-S2 arrow main part expanded sectional view. It is a principal part expanded sectional view at the time of a deformation | transformation of the conventional radiation shielding window.

  As shown in FIG. 1, the radiation shielding safety glass 10 of the present embodiment is configured such that a cover plate glass 2 is bonded to both surfaces of a radiation shielding plate glass 1 via a resin layer 3. And in a part of peripheral part of the radiation shielding safety glass 10, the end surface 1a of the radiation shielding plate glass 1 is configured to protrude from the end surface 2a of the cover plate glass 2. The protruding amount T of the end face 1 a is determined according to the thickness of the cover plate glass 2.

  As shown in FIG. 2A, the radiation shielding safety glass 10 of the present embodiment is formed in a rectangular shape when viewed from the front, and the radiation shielding plate glass 1 is formed only on one side (lower side) of the four sides of the peripheral portion. The end face 1a of the cover plate glass 2 protrudes from the end face 2a. At the other side (upper side and side side) of the peripheral edge of the radiation shielding safety glass 10, the end surface 1b of the radiation shielding plate glass 1 and the end surface 2b of the cover plate glass 2 are flush with each other.

Radiation shield plate glass 1 of this embodiment, the mass percentage of the oxide _{equivalent, SiO 2 10~35%, PbO 55~80} %, B 2 O 3 0~10%, Al 2 O 3 0~10%, SrO It contains 0 to 10%, BaO 0 to 10%, Na ₂ O 0 to 10%, K ₂ O 0 to 10%, and has a high radiation shielding ability because PbO is 55% or more. .

  By containing such a glass composition, sufficient gamma ray shielding ability as a glass characteristic can be obtained, and devitrification does not occur even if a large amount of PbO is contained in the glass composition. Moreover, since the composition range described above is a composition range that is very difficult to devitrify, it is possible to easily increase the glass thickness without devitrification. Therefore, the gamma ray shielding ability of glass can be extremely enhanced, it becomes possible to shield gamma rays generated from positron nuclides accurately, doctors and laboratory technicians who perform PET examinations, nurses, etc. are cumulatively exposed to gamma rays, It is possible to effectively avoid situations such as exposure.

  The reason for limiting the composition range of the radiation shielding plate glass 1 as described above is as follows.

SiO ₂ is a component that forms a network of glass. Its content is 10 to 35%, preferably 15 to 30%, more preferably 20 to 30%. When the content of SiO ₂ exceeds 35%, the high temperature viscosity of the glass becomes high, melting and molding become difficult, and the gamma ray shielding ability decreases. On the other hand, when the content of SiO ₂ is less than 10%, the components forming the skeleton of the glass become too small, the glass becomes structurally unstable, and the water resistance of the glass is lowered.

  PbO is a component for shielding gamma rays. Its content is 55 to 80%, preferably 62 to 80%, more preferably 67 to 80%, most preferably 70 to 80%. When the content of PbO exceeds 80%, components other than PbO are relatively reduced, and the glass becomes thermally unstable. On the other hand, if the content of PbO is less than 55%, the gamma ray shielding ability is lowered.

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 0.1-8%, more preferably 0.1-5%. When the content of B ₂ O ₃ is more than 10%, the water resistance of the glass is lowered.

Al ₂ O ₃ is a component that increases the thermal stability of the glass. The content is 0 to 10%, preferably 0 to 5%, more preferably 0 to 3%. When the content of Al ₂ O ₃ is more than 10%, the high temperature viscosity of the glass becomes high, melting and forming become difficult, and the gamma ray shielding ability is lowered.

  SrO and BaO are components that adjust the viscosity and devitrification of glass, and are components that enhance the gamma ray shielding ability. The content is 0 to 10%, preferably 0 to 8%, more preferably 0 to 5%. If the content of SrO or BaO exceeds 10%, the glass becomes thermally unstable.

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%. When these contents are more than 10%, the gamma ray shielding ability is lowered.

Sb ₂ O ₃ is a component that acts as a fining agent. Its content is 100 ppm to 2% (preferably 200 ppm to 2%, 500 ppm to 2%, 1000 ppm to 2%, more than 5000 ppm to 2%, 5500 ppm to 2%, 6000 ppm to 2%). When the content of Sb ₂ O ₃ is less than 100 ppm, it becomes difficult to obtain a clarifying power and it is difficult to reduce bubbles in the glass. On the other hand, when the content of Sb ₂ O ₃ exceeds 2%, Sb ₂ O ₃ is expensive and the raw material cost increases.

Cl ₂ is a component that acts as a fining agent. The content is 0 ppm to 2%, preferably 200 ppm to 2%, more preferably 500 ppm to 2%, and still more preferably 1000 ppm to 1%. When the content of Cl ₂ is more than 2%, the amount of evaporation of Cl ₂ becomes too large, and the glass is easily deteriorated. Note that the Cl ₂ content indicates the remaining amount in the glass.

Sb ₂ O ₃ used as a fining agent generates a large amount of fining gas (oxygen gas) by a chemical reaction due to a change in the valence of Sb ions in a temperature range of 900 ° C. or higher. In particular, a large amount of clarified gas is generated at a low temperature of 1000 to 1200 ° C. Further, Cl ₂ is decomposed and evaporated in a temperature range of 900 ° C. or higher to generate a clarified gas (chlorine gas or the like). Therefore, by using Sb ₂ O ₃ or Cl ₂ as a fining agent, even if the temperature range from the vitrification reaction to the homogenization melting is low, a high fining effect can be obtained. A radiation shielding plate glass which does not exist can be obtained efficiently.

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

  When manufacturing this radiation shielding plate glass 1, after melt | dissolving a glass raw material in a melting furnace and making it into molten glass, the molten glass is shape | molded by the roll-out method to make plate glass.

  Moreover, as for the radiation shielding safety glass 10 of this embodiment, laminated glass has a visible light average transmittance of 84%. The total light transmittance at a wavelength of 400 nm is 13.1%. Thus, sufficient visibility can be ensured.

In addition, in this specification, visible light average transmittance | permeability means the average transmittance | permeability of visible light (wavelength 380-780 nm) based on JISR3106. The thickness “about 10 mm” means a matter when the radiation shielding plate glass is assumed to be a plate glass having a plate thickness of 10 mm, and “total light transmittance” means JIS K7105 (light source: CIE standard light A). ) Or JIS K7361 (light source: CIE standard light D ₆₅ ), measured using CIE standard light A or CIE standard light D _65, and a total transmitted light beam with respect to a parallel incident light beam on a light transmitting plate Is the ratio. In general, it means the total light transmittance measured for a sheet glass using a measuring device called a haze meter.

Cover plate glass 2 of the present embodiment, the mass percentage of the oxide _{equivalent, SiO 2 50~65%, Al 2} O 3 3~14%, 0~4% MgO, CaO 0~2.9%, SrO 2~ 13%, BaO 2-13%, MgO + CaO + SrO + BaO 17-27%, Li ₂ O 0-1%, Na ₂ O 2-10%, K ₂ O 2-13%, Li ₂ O + Na ₂ O + K ₂ O 7-15% , ZrO ₂ 1 to 9%, TiO ₂ 0 to 5%, Sb ₂ O ₃ 0 to 1%, As ₂ O ₃ 0 to 1%.

  Since this cover plate glass 2 essentially does not contain Pb, raw materials containing Pb are not spilled during glass production, thereby causing environmental pollution.

Moreover, since the cover plate glass 2 contains 50 to 65% SiO ₂ and ₃ to 14% Al ₂ O ₃ , transparency is hardly lowered even when the surface is cleaned, and deformation or discoloration due to water absorption may occur. Absent. In addition, since the surface hardness is high, scratches are difficult to occur, and cracks due to scratches and transparency are unlikely to occur. That is, if the SiO ₂ content is less than 50%, the chemical durability is low, so “burn” occurs after the glass surface is cleaned, and the transparency tends to decrease. It is not preferable because it tends to deteriorate. Al ₂ O ₃ is a component that improves the surface hardness of the glass and improves the chemical durability of the glass. If its content is less than 3%, the surface hardness becomes low and scratches are found. Easy to crack. Further, since the chemical durability is low, after the glass surface is cleaned, “burning” occurs, and the transparency tends to decrease. When Al ₂ O ₃ is more than 14%, the meltability is deteriorated and the liquidus temperature is likely to be high, which is not preferable.

ZrO ₂ is a component that improves the radiation shielding ability and the chemical durability of the glass, and its content is 1 to 9%, preferably 1 to 8%. If ZrO ₂ is less than 1%, the radiation shielding ability is low, and the chemical durability of the glass tends to be lowered. If it is more than 9%, devitrification is likely to occur during the molding of the glass, and the molding is difficult. Since it becomes difficult, it is not preferable.

  MgO, CaO, SrO, BaO are components that improve the meltability of the glass. In particular, SrO and BaO are components that are excellent in the effect of enhancing the radiation shielding ability, and the total amount of MgO, CaO, SrO, BaO is 17-27%. When the total amount of these components is less than 17%, the radiation shielding ability is lowered and the meltability is easily deteriorated. If it exceeds 27%, the glass tends to be devitrified.

  A suitable content of MgO is 0 to 4%, and CaO is 0 to 2.9%. Moreover, the suitable content of BaO and SrO is 2 to 13%.

Li ₂ O, Na ₂ O, and K ₂ O are components that improve the meltability of the glass, and the total amount of these components is 7 to 15%. When the total amount of these components is less than 7%, melting becomes difficult, and when it exceeds 15%, the chemical durability is lowered.

_Further, preferable content of Li 2 O, Na ₂ O and _{K 2} O, 0 to 1%, respectively, 2-10%, is 2-13%.

In addition to the above components, TiO ₂ may be added up to 5%, P ₂ O _{5 up} to 3%, and Sb ₂ O ₃ and As ₂ O _{3 up} to 1%.

  The cover plate glass 2 can be produced by an existing molding method. However, when the plate is produced by a float method, it is excellent in smoothness, so that it does not need to be polished and scratches due to polishing do not occur.

  As the resin layer 3 of this embodiment, polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer (EVA), fluororesin (THV), etc. can be used, and it is used as a liquid adhesive for adhesion of cover plate glass. However, the form of the resin film is preferable in terms of easy handling. The thickness of the resin layer is preferably 50 to 2000 μm.

  Moreover, when bonding the cover plate glass from which a thermal expansion coefficient differs, it is preferable not to use the resin by thermosetting but to use the thing which carries out reaction hardening at normal temperature using a hardening | curing agent, and a photocuring type. In addition to an ultraviolet curable resin mainly composed of epoxy acrylate, which has a proven record as a building material, other resins such as an acrylic resin, an epoxy resin, and a silicone resin can also be used. Thus, when the resin layer 3 is made of a photo-curing resin, it can be cured by irradiation with ultraviolet rays or the like at room temperature, and even when heat-resistant plate glasses having different thermal expansion coefficients are combined, the heat-resistant plate glass is warped or damaged. This is preferable because the variation of combinations increases. Moreover, if the thickness of the resin layer 3 is 50-2000 micrometers, a deformation | transformation can be absorbed with the resin layer 3, and it becomes possible to match | combine the cover plate glass from which a dimensional change rate differs.

  Next, the manufacturing method of the radiation shielding safety glass 10 of this embodiment is demonstrated.

  The manufacturing method of the radiation shielding safety glass 10 according to the present embodiment includes a laminating step of laminating the cover plate glass 2 on the radiation shielding plate glass 1 through a PVB resin film having a thickness of 300 μm, and an autoclave obtained by the laminating step. It is comprised from the sticking process bonded together by thermocompression bonding etc. etc.

  First, a sheet glass for radiation shielding with a specific gravity of 4.35 having a lead equivalent performance of 1.1 mmPb and a thickness of 7 mm was made by a roll-out method, slowly cooled and polished on both sides, and then a width of 1000 mm × The radiation shielding plate glass 1 is obtained by processing into a length of 1600 mm.

  Next, after preparing and melting the batch raw material so as to have the above-described composition, a plate glass having a thickness of 1.8 mm is made by a float process, and processed into a size of width 1000 mm × length 1595 mm. Get.

  Next, a PVB resin film having a thickness of 300 μm is disposed on one side of the radiation shielding plate glass 1, and the cover plate glass 2 is allowed to stand thereon. At this time, by arranging a spacer on one side of the peripheral edge of the radiation shielding plate glass 1, the end surface 1 a of the radiation shielding plate glass 1 is protruded by 5 mm from the end surface 2 a of the cover plate glass 2.

  Next, the obtained laminate is bonded by thermocompression bonding in an autoclave. And the same operation | work is performed also on the other surface of the radiation shielding plate glass 1, and the cover plate glass 2 is affixed also on another surface.

  In this way, as shown in FIG. 1, the radiation shielding safety glass 10 in which the cover plate glass 2 is adhered to both surfaces of the radiation shielding plate glass 1 via the resin layer 3 is manufactured.

  Next, the radiation shielding window 20 according to the present embodiment will be described with reference to FIGS.

  The radiation shielding window 20 of the present embodiment is configured by fixing the radiation shielding safety glass 10 to the frame body 4 via the setting block 5. That is, the radiation shielding window 20 includes a rectangular radiation shielding safety glass 10 that is rectangular in front view, a rectangular frame 4 that surrounds all four sides of the peripheral edge of the radiation shielding safety glass 10, and a lower frame 4 a of the frame 4. A total of two setting blocks 5 arranged in the groove and supporting the lower side of the radiation shielding safety glass 10, and the glass surface near the peripheral edge of the cover plate glass 2 and the inner wall of the frame 4 on the entire circumference of the radiation shielding safety glass 10. It is comprised from the backup material 6 and the sealing material 7 which were interposed between the parts 4c.

  As shown in FIG. 2 (b), since the end surface 1a of the radiation shielding plate glass 1 protrudes from the end surface 2a of the cover plate glass 2 at the lower side of the radiation shielding safety glass 10, the radiation shielding plate glass 1 is set at the end surface 1a. While being in direct contact with the block 5, a gap is formed between the end surface 2 a of the cover plate glass 2 and the setting block 5.

  Therefore, even if an external force such as an earthquake is applied to the radiation shielding window 20 of the present embodiment and the frame body 4 is deformed, as shown in FIG. 3, as shown in FIG. Since the gap can be ensured, an external force such as an earthquake or a stress due to its own weight does not concentrate on the lower side of the cover plate glass 2 through the setting block 5, and the cover plate glass 2 can be prevented from being damaged.

  Although the radiation shielding safety glass 10 and the radiation shielding window 20 of the present embodiment have been described above, the present invention can also be implemented in other embodiments.

  For example, in the said embodiment, the end surface 1a of the radiation shielding plate glass 1 is made to protrude rather than the end surface 2a of the cover plate glass 2 only in one side (lower side) of the four sides of the peripheral part of the radiation shielding safety glass 10 having a rectangular front view. However, the present invention is by no means limited to this. For example, as shown in FIG. 4, among the four sides of the peripheral portion of the radiation shielding safety glass 30, two opposite sides (lower side and upper side) The end surface 1 a of the radiation shielding plate glass 1 may be protruded from the end surface 2 a of the cover plate glass 2. The radiation shielding window 40 is configured by supporting the upper and lower sides of the radiation shielding safety glass 30 with a total of four setting blocks 5 disposed in the lower frame 4a and the upper frame 4b of the frame body 4, respectively. Also good. Further, the end face 1 a of the radiation shielding plate glass 1 may be protruded from the end face 2 a of the cover plate glass 2 in all four sides of the peripheral edge of the radiation shielding safety glass 10.

  Further, as in the above-described embodiment, it is not always necessary to project the end face 1a of the radiation shielding plate glass 1 over the entire one side (lower side) of the radiation shielding safety glass 10, but one side (lower side) of the radiation shielding safety glass 10 ), The end face 1a of the radiation shielding plate glass 1 may be protruded. It is sufficient that the end surface 1a of the radiation shielding plate glass 1 protrudes from the end surface 2a of the cover plate glass 2 at least in a portion that contacts the setting block 5 when the radiation shielding window is configured.

  Moreover, in the said embodiment, although the end surface 1a of the radiation shielding plate glass 1 is made to protrude in a step shape with a step with respect to the end surface 2a of the cover plate glass 2, like the radiation shielding safety glass 50 shown in FIG. After laminating and laminating the cover plate glass 2 on both surfaces of the radiation shielding plate glass 1 via the resin layer 3, the peripheral portion of the laminate is ground and polished into a semicircular cross section, thereby providing the radiation shielding plate glass. One end face 1 a may be protruded with respect to the end face 2 a of the cover plate glass 2. In this case, if the surface roughness of both end faces is 50 μm or less in Ra, the possibility of breakage can be further reduced, which is preferable.

  Moreover, like the radiation shielding safety glass 60 shown in FIG. 6, the edge part 1a of the radiation shielding plate glass 1 is made into the end surface 2a of the cover plate glass 2 by grinding and grind | polishing the peripheral part of a glass laminated body in a trapezoid cross-sectional shape. You may make it protrude. As described above, the cross-sectional shape of the grinding and polishing processing for the peripheral portion of the glass laminate can be variously changed in consideration of the size of the radiation shielding safety glass to be manufactured, the processing cost, and the like.

  In addition, the radiation shielding window 20 of the above embodiment can be applied to a wall of a facility that handles radiation, such as a medical institution, or can be applied to a screen for shielding radiation. When applied to a partition, it is preferable to apply the radiation shielding window 20 to the entire surface of the partition from the viewpoint of visibility.

Further, as the radiation shielding plate glass constituting the radiation shielding safety glass, for example, in percent by mass of oxide _{equivalent, SiO 2 10~40%, PbO 45~80} %, B 2 O 3 0~10%, Al 2 O 3 _{0~10%, SrO 0~10%, BaO} 0~10%, Na 2 O 0~10%, it is also possible to employ a glass sheet containing the composition of K 2 O 0~10%.

According to the radiation shielding safety glass using the radiation shielding plate glass of this composition, it can be used in a place where a strong source of radiation exists. Here, when the PbO content is more than 80%, components other than PbO are relatively reduced, and the plate glass becomes thermally unstable. When the PbO content is less than 45%, the gamma ray shielding ability is reduced, and the strong source Use with is difficult. Further, when the content of SiO ₂ is more than 40%, the content of PbO is limited, so that the radiation shielding ability is reduced. When the content is less than 10%, the components forming the glass skeleton are reduced, and the structure Become unstable.

Furthermore, as the radiation shielding plate glass constituting the radiation shielding safety glass, for example, SiO ₂ 40 to 55%, PbO 30 to 45%, B ₂ O ₃ 0 to 10%, Al ₂ O, in terms of mass percentage in terms of oxide. _{3 0~10%, SrO 0~10%,} BaO 0~10%, Na 2 O 0~10%, it is also possible to employ a glass sheet containing the composition of K 2 O 0~10%.

According to the radiation shielding safety glass using the radiation shielding plate glass having this composition, it can be used in a place where a weak source of radiation exists. Here, if the content of PbO exceeds 45%, the glass becomes too heavy for the required shielding ability. On the other hand, if it is less than 30%, the gamma ray shielding ability decreases, and it becomes difficult to use it in a weak source. On the other hand, when the content of SiO ₂ exceeds 55%, the high-temperature viscosity is high, and processing and molding become difficult. On the other hand, if it is less than 40%, PbO is excessive with respect to the required shielding ability.

  Moreover, in the said embodiment, although radiation shielding plate glass is shape | molded by the rollout method, you may employ | adopt other shaping | molding methods, such as a casting method, for example. The roll-out method is suitable for forming a sheet glass having a thickness of 20 mm or less, and the casting method is suitable for forming a sheet glass having a thickness of 20 mm or more. As the radiation shielding plate glass, for example, a plate glass having a thickness of 400 mm can be used. Moreover, the radiation shielding plate glass which has the radiation shielding capability equivalent to 1200 mm of heavy concrete with a specific gravity of 3.4 by cobalt 60 irradiation can also be used.

  Moreover, as cover glass which comprises radiation shielding safety glass, common glass, such as an alkali free glass, soda glass, borosilicate glass, an aluminosilicate, can also be used, for example. Moreover, tempered glass can also be used as needed.

As the alkali-free glass used in the cover glass, in percent by mass of oxide _{equivalent, SiO 2 40~70%, Al 2} O 3 6~25%, B 2 O 3 5~20%, MgO 0~ Containing 10%, CaO 0-15%, BaO 0-30%, SrO 0-10%, ZnO 0-10%, consisting essentially of an alkali-free glass containing no alkali metal oxide. preferable. Such glass has excellent properties such as Young's modulus, strain point, thermal expansion coefficient, chemical resistance, meltability, and moldability.

  The reason why the composition range is limited will be described below.

SiO ₂ is a component made of a glass network, the content thereof is 40% to 70%. When SiO ₂ is less than 40%, the chemical resistance is deteriorated and the strain point is lowered to deteriorate the heat resistance. If it exceeds 70%, the high-temperature viscosity becomes high and the meltability deteriorates, and the devitrified material of cristobalite tends to precipitate. The preferable content of SiO ₂ is 45 to 68%, more preferably 58 to 67%.

Al ₂ O ₃ is a component that increases the heat resistance and devitrification resistance of glass, and its content is 6 to 25%. When the Al ₂ O ₃ content is less than 6%, the devitrification temperature is remarkably increased, and devitrification is likely to occur in the glass. The preferable content of Al ₂ O ₃ is 10 to 20%, more preferably 15 to 18%.

B ₂ O ₃ is a component that acts as a flux and lowers viscosity to facilitate melting, and its content is 5 to 20%. When B ₂ O ₃ is less than 5%, the effect as a flux becomes insufficient, and when it is more than 20%, hydrochloric acid resistance is lowered, strain point is lowered and heat resistance is deteriorated. The preferable content of B ₂ O ₃ is 7.5 to 15%, and the more preferable content is 8.5 to 15%.

  MgO is a component that lowers the high temperature viscosity without lowering the strain point and facilitates melting of the glass, and its content is 0 to 10%. When there is more MgO than 10%, the acid resistance of glass will fall remarkably. The preferable content of MgO is 0 to 3.5%, and the more preferable content is 0 to 3%.

  CaO is also a component that functions in the same manner as MgO, and its content is 0 to 15%. When there is more CaO than 15%, acid resistance will fall remarkably. The preferable content of CaO is 0 to 10%, and the more preferable content is 6 to 10%.

  BaO is a component that improves the chemical resistance of glass and improves devitrification, and its content is 0 to 30%. When there is more BaO than 30%, a strain point will fall and heat resistance will worsen. The preferable content of BaO is 0 to 20%, more preferably 0.1 to 5.0%.

  SrO is also a component having the same function as BaO, and its content is 0 to 10%. When SrO is more than 10%, devitrification increases, which is not preferable. A preferable content of SrO is 0 to 7%.

  BaO and SrO are components that also affect the density and thermal expansion coefficient of the glass. In order to obtain a low-density, low-expansion glass, the total amount is suppressed to 6% or less, preferably 4% or less. It is preferable.

  ZnO is a component that improves acid resistance and devitrification, and its content is 0 to 10%. However, if ZnO is more than 10%, the glass tends to be devitrified, and the strain point is lowered to deteriorate the heat resistance. The preferable content of ZnO is 0 to 7%, more preferably 0 to 5%.

  On the other hand, if the total amount of MgO, CaO, SrO, BaO and ZnO is less than 5%, the viscosity at high temperature increases, the meltability deteriorates and the glass tends to devitrify, which is not preferable. On the other hand, if it exceeds 20%, the density of the glass becomes high, which is not preferable.

In the present invention, in addition to the above components, ZrO ₂ , TiO ₂ , Fe ₂ O ₃ , P ₂ O ₅ , Y ₂ O ₃ , Nb ₂ O ₃ , La ₂ O _3, etc. may be combined up to 5%. Can be contained.

ZrO ₂ is a component that improves the chemical resistance of glass, particularly the acid resistance, and lowers the high-temperature viscosity to improve the meltability. The content of ZrO ₂ is 0 to 5%, preferably 0.1 to 4%. If it exceeds 5%, the devitrification temperature rises and the devitrified foreign matter of zircon tends to precipitate.

TiO _{2 is} also a component that improves chemical resistance, particularly acid resistance. At the same time, TiO ₂ is a component that lowers the viscosity at high temperature, improves the meltability, and further prevents coloring due to ultraviolet rays. That is, ultraviolet rays may be irradiated to remove organic substances on the glass substrate. However, if the glass substrate is colored with ultraviolet rays, the transmittance decreases, which is not preferable. Therefore, this type of glass substrate is required not to be colored by ultraviolet rays. However, if TiO ₂ is more than 5%, the glass tends to be colored, which is not preferable.

Furthermore, P ₂ O _{5 is} also generally used as a fluxing agent, but it is not preferable because it causes phase separation of the glass and significantly reduces chemical resistance. If CuO is contained, the glass will be colored.

  Moreover, PbO generally used as a flux significantly reduces the chemical resistance of glass. At the same time, PbO is not preferable because it may volatilize from the surface of the melt during melting and contaminate the environment.

Moreover, in this invention, it is possible to add another component in the range which does not impair a characteristic other than the said component. For example, components such as As ₂ O ₃ , Sb ₂ O ₃ , F ₂ , Cl ₂ , SO ₃ , SnO ₂ and metal powders such as Al and Si can be added as fining agents.

  In addition, when high visibility is not always required, for example, when used for purposes other than radiation inspection in medical facilities, the average visible light transmittance of the radiation shielding safety glass is 30% or more regardless of the thickness. Can be used.

  Examples of radiation shielding safety glass and radiation shielding windows according to the present invention will be described below.

  The radiation shielding safety glass of this example has a thickness of 1. mm through a resin layer having a thickness of 300 μm on both sides of a radiation shielding plate glass having a specific gravity of 4.35 and a thickness of 7 mm having a lead equivalent performance of 1.1 mmPb. A cover plate glass of 8 mm is attached. This radiation shielding safety glass has a thickness of about 12 mm. And one side (lower side) of the peripheral part of the radiation shielding safety glass of the present embodiment is ground and polished into a semicircular shape with a radius of 7 mm, and the end face of the radiation shielding plate glass is about 1 mm from the end face of the cover plate glass. The surface roughness of both end faces was 30 μm in terms of Ra.

  In order to confirm the performance of the radiation shielding safety glass, a test for forcibly deforming the test frame was performed. The size of the radiation shielding safety glass used for the test is 1000 mm wide x 1600 mm high. The periphery of the radiation shielding safety glass is inserted into the groove of the test frame by about 15 mm, and the lower side is supported by two setting blocks. Then, after a backup material was inserted between the test frame and the glass, a silicone sealing material was filled.

  a. In-plane deformation test: A test in which the lower side of the test frame on which radiation shielding safety glass is installed is bolted to the virtual housing, and the upper frame is deformed in the in-plane direction with a hydraulic jack to check for glass breakage. . Even if the deformation amount ± 32 mm (interlayer displacement = ± 1/50) was repeated 50 times, the cover plate glass was not damaged.

  As a comparative example, the same test was performed on one side (lower side) of the peripheral edge that was not ground or polished (see FIG. 7). As a result, cracks occurred in the cover plate glass when it was reciprocated 10 times.

  b. Out-of-plane deformation test: A test in which the lower side of the test frame on which radiation-shielding safety glass is installed is bolted to the virtual housing, and the upper frame is deformed in the out-of-plane direction with a hydraulic jack to check for glass breakage. . Even if the deformation amount ± 32 mm (interlayer displacement = ± 1/50) was repeated 50 times, the cover plate glass was not damaged.

  As a comparative example, the same test was performed on one side (lower side) of the peripheral edge portion that was not ground and polished (see FIG. 7). As a result, cracks occurred in the cover plate glass when it was reciprocated five times.

  The radiation shielding safety glass and radiation shielding window according to the present invention can be applied to radiation academic research facilities such as cosmic rays other than medical facilities, nuclear facilities, hot laboratories, and other facilities. For example, it can be applied to a nuclear power generation turbine building, a solid nuclear waste storage, a recirculation pump, a window of a used nuclear fuel transport container storage facility, a drum transfer device that handles radioactive materials, a window of a heavy machine, or the like.

10, 30, 50, 60 Radiation shielding safety glass 20, 40 Radiation shielding window 1 Radiation shielding plate glass 1a End surface 2 Cover plate glass 2a End surface 3 Resin layer 4 Frame 5 Setting block

Claims (3)

A laminated glass in which a cover plate glass is bonded to a radiation shielding plate glass via a resin layer,
Radiation shielding safety glass characterized in that, at the peripheral edge of the laminated glass, the end face of the radiation shielding plate glass protrudes from the end face of the cover plate glass.   The radiation shielding safety glass according to claim 1, wherein the laminated glass has an average visible light transmittance of 75% or more. A radiation shielding window formed by fixing a laminated glass, in which a cover plate glass is bonded to a radiation shielding plate glass via a resin layer, to a frame body via a setting block,
In the peripheral part of the laminated glass, the end face of the radiation shielding plate glass protrudes from the end face of the cover plate glass,
A radiation shielding window having a gap between an end face of the cover plate glass and the setting block.

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