Spinal magnetometer

Abstract

A thermal-insulation container (10) is provided with an inner container (11), and an outer container (14) that envelops the inner container (11) with a gap (15) therebetween. The inner container (11) and the outer container (14) are constituted of fiber-reinforced plastic obtained by impregnating a base material with resin. The inner container (11) is provided with a cylindrical container (13) and a second cylindrical container (22) that have an accommodation part (23) and an accommodation part (24) for storing a refrigerant (16) inside thereof, and a refrigerant injection tube (12) for injecting the refrigerant (16). The accommodation part (24) communicates with the accommodation part (23). The base material constituting a predetermined region of the second cylindrical container (22) and a predetermined region of the outer container (14) comprises a fabric and a unidirectional fiber sheet. The outer container (14) envelops the second cylindrical container (22) in a state where the unidirectional fiber sheet constituting the predetermined region of the second cylindrical container (22) and the unidirectional fiber sheet constituting the predetermined region of the outer container (14) face each another.

Description

[Technical field]

[0001] The present invention relates to a thermally insulated container and a magnetospinograph using the same. [Background technology]

[0002] In the medical field, a device (magnetospinometer) has been developed to measure the magnetic field generated by nerve activity in the spinal cord. The magnetospinometer uses a superconducting quantum interference device (SQUID) that utilizes the Josephson effect to measure the weak magnetic field generated in the spinal cord.

[0003] SQUIDs utilize the principle of superconductivity. To achieve a superconducting state, SQUIDs must be immersed in a refrigerant such as liquid helium at -269°C (4.2K). For this reason, the magnetometer requires an excellent insulated container that can store the refrigerant. Furthermore, the material that makes up the insulated container must be non-magnetic, so it is not affected by magnetism.

[0004] For example, Patent Document 1 discloses a cryogenic container including an inner container made of fiber reinforced plastics (hereinafter referred to as "FRP") and an outer container surrounding the inner container, and a magnetic detection device including the cryogenic container. The inner container is filled with a liquid having a low boiling point, and a magnetic detection sensor is disposed in the liquid. The gap between the inner container and the outer container is in a vacuum state. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-302933 Summary of the Invention [Problem to be solved by the invention]

[0006] Since the magnetospinometer measures a weak magnetic field, it is necessary to shorten the distance (lift-off) between the SQUID and the measurement site of the spinal cord as much as possible. In particular, the insulating container between the SQUID and the measurement site of the spinal cord must have a thin wall thickness and be rigid enough to withstand external stress, internal pressure, and external pressure while maintaining its insulating function.

[0007] The inner and outer containers disclosed in Patent Document 1 have thick walls to enhance their thermal insulation and rigidity, which makes it difficult for the SQUID to sense weak magnetic fields.

[0008] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an insulated container having a thin wall and high rigidity, and a magnetospinograph using the same. [Means for solving the problem]

[0009] In order to achieve the above object, [1] the insulated container of the present invention comprises an inner container and an outer container surrounding the inner container via a gap, the inner container and the outer container being made of fiber-reinforced plastic in which a base material containing fibers is impregnated with resin, the inner container comprises a cylindrical container and a second cylindrical container each having a storage portion for storing a refrigerant therein, and a refrigerant injection tube for injecting the refrigerant into the cylindrical container, the storage portion of the second cylindrical container is connected to the storage portion of the cylindrical container, the base material constituting a predetermined region of the second cylindrical container and a predetermined region of the outer container comprises a woven fabric and a unidirectional fiber sheet formed by aligning a plurality of fibers in one direction, and the outer container surrounds the second cylindrical container with the unidirectional fiber sheet constituting the predetermined region of the second cylindrical container and the unidirectional fiber sheet constituting the predetermined region of the outer container facing each other.

[0010] [2] The fibers of the unidirectional fiber sheet constituting the specified region of the second cylindrical container may be perpendicular to the extending direction of the axis of the second cylindrical container.

[0011] [3] The fibers of the unidirectional fiber sheet constituting the specified region of the outer container may be parallel to the extending direction of the axis of the second cylindrical container.

[0012] [4] In addition, the woven fabric and the unidirectional fiber sheet constituting the specified region of the second cylindrical container may be composed of at least one type selected from the group consisting of glass fiber, alumina fiber, and carbon fiber.

[0013] [5] In addition, the woven fabric and the unidirectional fiber sheet constituting the specified region of the outer container may be made of at least one type selected from the group consisting of glass fiber, alumina fiber, and carbon fiber.

[0014] [6] The amount of resin in the fiber reinforced plastic constituting the heat-insulating container may be 15 to 50 wt % with respect to the total weight of the fiber reinforced plastic.

[0015] In addition, [7] the resin may include an epoxy resin.

[0016] Further, [8] a spinal magnetometer equipped with an insulated container according to the present invention comprises a superconducting quantum interferometer for detecting a magnetic field generated from a living body, and an insulated container described in any one of [1] to [7], wherein the superconducting quantum interferometer is contained in a state immersed in a refrigerant stored in the container portion of the second cylindrical container.

[0017] [9] Also, a measurement surface of the superconducting quantum interference meter may be configured to face the predetermined area of ​​the outer container and the predetermined area of ​​the second cylindrical container. Effect of the Invention

[0018] According to the present invention, it is possible to provide an insulated container having a thin wall and high rigidity, and a magnetospinometer using the same. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic side view of an insulated container according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic top view of an insulated container according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 3 is a cross-sectional view taken along line BB in FIG. 2. [Diagram 5] FIG. 2 is a schematic diagram showing a fiber-reinforced plastic fiber constituting a refrigerant injection tube wound in a spiral shape. [Figure 6] FIG. 2 is a schematic diagram of a unidirectional fiber sheet made of flat yarns, the flat yarns being held in place by stop yarns. [Figure 7] FIG. 2 is a schematic diagram showing a unidirectional fiber sheet constituting the cylindrical portion of the cylindrical container, wound in a spiral shape. [Figure 8] FIG. 2 is a schematic cross-sectional view showing a cylindrical portion having a wall with a two-layer structure. [Figure 9] 1 is a schematic cross-sectional view of a magnetospinograph using a heat-insulating container according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, a heat-insulating container according to an embodiment of the present invention (hereinafter also referred to as "embodiment") and a magnetospinograph using the same will be described in detail. The following embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be practiced with appropriate modifications within the scope of its gist.

[0021] (Embodiment 1) The insulated container 10 of the first embodiment will be described. Fig. 1 shows the insulated container 10 as viewed from the side. Fig. 2 shows the insulated container 10 as viewed from above. Fig. 3 is a cross-sectional view of the insulated container 10 shown in Fig. 2, taken along line AA. As shown in Fig. 3, the insulated container 10 is a container for storing a refrigerant 16. The insulated container 10 includes an inner container 11 and an outer container 14 that surrounds the inner container 11 with a gap 15 therebetween.

[0022] The inner container 11 and the outer container 14 will now be described.

[0023] [Inner container 11] The inner container 11 includes a cylindrical container 13 having a storage section 23 for storing the refrigerant 16 therein, a refrigerant injection tube 12 attached to the cylindrical container 13, and a second cylindrical container 22 having a storage section 24 for storing the refrigerant 16 therein. The storage section 24 is connected to the storage section 23. The cylindrical container 13 has an upper surface section 131 constituting the upper surface, a cylindrical section 132 constituting the side wall, and a bottom surface section 133 constituting the bottom surface. The refrigerant injection tube 12 is attached to the upper surface section 131. The refrigerant injection tube 12 may be attached to the cylindrical section 132. The second cylindrical container 22 has a cylindrical section 122 constituting the side wall, and a bottom surface section 123 that closes one end of the cylindrical section 122. Here, the "inside" of the inner container 11 refers to the area constituted by the surface that may come into contact with the refrigerant 16.

[0024] The refrigerant injection pipe 12, the cylindrical container 13 and the second cylindrical container 22 will be described.

[0025] [Refrigerant injection pipe 12] The refrigerant injection tube 12 is a tube for injecting the refrigerant 16 into the cylindrical container 13. The shape of the tube is not limited, but examples thereof include a cylindrical shape, an elliptical cylindrical shape, and a square cylindrical shape.

[0026] From the viewpoint of heat insulation and of exhibiting rigidity at room temperature and in the temperature range of -196°C or lower, the thickness of refrigerant injection tube 12 is, for example, 2 to 30 mm. Here, the "temperature range of -196°C or lower" is referred to as the "cryolow temperature range." The thickness of refrigerant injection tube 12 refers to the thickness of the wall of refrigerant injection tube 12 in a plane perpendicular to the longitudinal direction (height direction) of refrigerant injection tube 12.

[0027] The length of the refrigerant injection pipe 12 is appropriately set depending on the sizes of the outer container 14 and the inner container 11, and is, for example, 100 to 500 mm.

[0028] When refrigerant injection pipe 12 has a cylindrical shape, the diameter is, for example, 50 to 300 mm from the viewpoint of suppressing evaporation of the refrigerant, although this is not limited thereto.

[0029] When refrigerant injection pipe 12 has an elliptical cylindrical shape, the length of the major axis is, for example, 50 to 300 mm.

[0030] When refrigerant injection tube 12 has a rectangular cylindrical shape, the length of the diagonal in the cross section of the tube in a plane perpendicular to the longitudinal direction (height direction) of refrigerant injection tube 12 is, for example, 100 to 400 mm.

[0031] Refrigerant injection pipe 12 is made of fiber reinforced plastics (hereinafter referred to as "FRP"), a base material of which is impregnated with resin.

[0032] Here, the cured state of the resin constituting the FRP is a state in which the curing reaction has progressed completely (hereinafter referred to as the "C-stage state"). Unless otherwise specified in the following description, the cured state of the FRP is the C-stage state. This also applies to other embodiments.

[0033] 5, FRP base material 21 constituting refrigerant injection tube 12 is wound helically in the extension direction of axial core CL of refrigerant injection tube 12 to form a cylindrical shape in order to slow down the conduction of heat from the outside to cylindrical container 13 via refrigerant injection tube 12. Specifically, the fibers constituting base material 21 are wound helically so that the angle θ with respect to the extension direction of axial core CL of refrigerant injection tube 12 is 50 to 89°. From the viewpoints of the thermal conductivity and rigidity of refrigerant injection tube 12, angle θ is more preferably 55 to 70°.

[0034] The substrate 21 is made of at least one material selected from the group consisting of glass fiber, alumina fiber, and carbon fiber. The substrate 21 is preferably made of glass fiber from the viewpoints of cost, processability, and material availability, and from the viewpoint of reducing thermal conductivity in the normal temperature to cryogenic temperature range.

[0035] The resin to be impregnated into the substrate 21 is not limited, but examples thereof include an epoxy resin composition having an epoxy resin as a main component, a phenol resin composition having a phenol resin as a main component, or a polyimide resin composition having a thermosetting polyimide resin as a main component.

[0036] From the viewpoint of suppressing the conduction of heat to cylindrical container 13, the amount of resin impregnated into base material 21 (converted into solid content) is preferably 15 to 50 wt % with respect to the total weight of the FRP constituting refrigerant injection tube 12.

[0037] Here, the amount of resin to be impregnated into a substrate such as fiber can be expressed in parts by weight or resin amount (wt%). Parts by weight is the weight of resin when the weight of the substrate is 100 parts by weight. The resin amount (wt%) is the weight of resin attached to the substrate (fiber) relative to the total weight of the substrate and resin as a percentage, and can be calculated by the formula: resin amount (wt%) = (weight of resin (wt) x 100) / (weight of fiber (wt) + weight of resin (wt)). Unless otherwise specified, all resin amounts are calculated as solid content. The amount of resin calculated as solid content refers to the amount of resin excluding volatile components such as solvents.

[0038] The refrigerant injection tube 12 can be produced by, for example, a filament winding method. The method for producing the refrigerant injection tube 12 will be described later.

[0039] [Cylindrical container 13] The cylindrical container 13 is a bottomed cylindrical container having a storage section 23 for storing the refrigerant 16 therein. The storage section 23 is formed inside the cylindrical container 13. The shape of the cylindrical section 132 constituting the cylindrical container 13 is not limited, but examples of the shape include a cylindrical shape, an elliptical cylindrical shape, a square cylindrical shape, and the like.

[0040] The wall thickness of the cylindrical container 13 is 2 to 30 mm from the viewpoint of heat insulation and rigidity in the cryogenic temperature range. Here, the wall thickness of the cylindrical container 13 is the thickness of the cylindrical portion 132, and refers to the thickness of the wall constituting the cylindrical container 13 (cylindrical portion 132) in a plane perpendicular to the longitudinal direction (height direction) of the cylindrical container 13 (cylindrical portion 132).

[0041] The size of cylindrical container 13 is not limited, but for example, when used in a device for measuring the magnetic field of the human body, it is preferable that the size be large enough to store 50 to 150 liters of refrigerant in order to operate the device for a long period of time.

[0042] The cylindrical portion 132 is made of FRP in which a base material is impregnated with resin. Examples of the base material constituting the FRP include fibers, woven fabrics, and unidirectional fiber sheets in which multiple fibers are aligned in one direction. The base material constituting the FRP is preferably a fiber or a unidirectional fiber sheet in order to slow down the conduction of heat from the outside to the cylindrical container 13 via the refrigerant injection tube 12. The base material constituting the FRP may be made of a combination of two or more types of base materials, and a combination of fibers and a unidirectional fiber sheet is preferable.

[0043] When the base material is a fiber, the fiber is composed of at least one type selected from the group consisting of glass fiber, alumina fiber, and carbon fiber. The fiber is preferably alumina fiber from the viewpoint of reducing thermal conductivity in the cryogenic temperature range. The fiber constituting the FRP may be composed of two types of fiber. For example, two types of fiber, alumina fiber and glass fiber, can be used as the fiber constituting the FRP. The fiber of the FRP constituting the cylindrical part 132 is wound in a spiral shape with respect to the extending direction of the axis of the cylindrical part 132, although it is not limited thereto. The angle at which the fiber is wound is, for example, 50 to 89 degrees with respect to the extending direction of the axis of the cylindrical part 132.

[0044] When the substrate is a woven fabric, the woven fabric is formed by weaving the above-mentioned fibers. Examples of the weaving method of the woven fabric include satin weave, plain weave, and twill weave. The woven fabric is layered to form a tubular shape. For example, the woven fabric is layered so that the warp threads are at +45° and the weft threads are at -45° with respect to the extension direction of the axial core of the tubular part 132. The woven fabric may also be layered so that the warp threads are at 0° and the weft threads are at 90°. From the viewpoint of exhibiting quasi-isotropic rigidity, first, one woven fabric may be layered so that the warp threads are at +45° and the weft threads are at -45° with respect to the extension direction of the axial core of the tubular part 132, and another woven fabric may be layered on top of it so that the warp threads are at 0° and the weft threads are at 90°, and this layering may be repeated.

[0045] When the substrate is a unidirectional fiber sheet, the unidirectional fiber sheet is formed by arranging the above-mentioned fibers in one direction. FIG. 6 is a schematic diagram of the unidirectional fiber sheet seen from the front. As shown in FIG. 6, the unidirectional fiber sheet is formed by arranging a plurality of flat yarns 66 in one direction. The unidirectional fiber sheet may be held by a stopper thread 65 so that the aligned flat yarns 66 do not collapse. The unidirectional fiber sheet is wound in a spiral shape with respect to the extension direction of the axis of the tubular part 132 so that the unidirectional fiber sheet forms a cylindrical shape. For example, as shown in FIG. 7, the unidirectional fiber sheet is wound in a spiral shape so that the angle φ between the fibers of the flat yarns 66 and the extension direction of the axis CL of the tubular part 132 is 50 to 89 degrees.

[0046] The resin to be impregnated into the base material constituting the cylindrical portion 132 is not limited, but may be an epoxy resin composition mainly made of epoxy resin, a phenol resin composition mainly made of phenol resin, or a polyimide resin composition mainly made of thermosetting polyimide resin. From the viewpoint of having rigidity and toughness in the range from room temperature to extremely low temperature, and from the viewpoint of ensuring good processability, the resin is preferably an epoxy resin composition. The resin may be a mixture of two or more resin compositions.

[0047] The resin amount (solid content equivalent) of the cylindrical portion 132 is preferably 15 to 50 wt % with respect to the total weight of the FRP constituting the cylindrical portion 132, from the viewpoint of maintaining the rigidity of the cylindrical portion 132 when a refrigerant of -196°C or less is stored.

[0048] Top surface portion 131 and bottom surface portion 133 of cylindrical container 13 are made of FRP, a base material impregnated with resin. The base material has a structure in which a plurality of woven fabrics are laminated. From the viewpoint of making the expansion and contraction behavior of cylindrical container 13 and refrigerant injection tube 12 and the expansion and contraction behavior of top surface portion 131 and bottom surface portion 133 the same in the normal temperature to cryogenic temperature range, the resin is preferably the same as the resin that constitutes cylindrical portion 132 and refrigerant injection tube 12. The resin amount (solid content equivalent) of the FRP that constitutes top surface portion 131 and the resin amount (solid content equivalent) of the FRP that constitutes bottom surface portion 133 are 15 to 50 wt % with respect to the total weight. The thickness of top surface portion 131 and bottom surface portion 133 is the same as the thickness of cylindrical portion 132.

[0049] The coolant 16 stored in the cylindrical container 13 and the second cylindrical container 22 may include, but is not limited to, liquid oxygen, liquid nitrogen, liquid helium, etc. In cryogenic applications for measuring the magnetic field of the spinal cord, the preferred coolant 16 is liquid helium.

[0050] A method for producing the cylindrical container 13 will be described later.

[0051] [Second cylindrical container 22] The second cylindrical container 22 has a cylindrical portion 122 constituting a side wall, and a bottom portion 123 closing one end of the cylindrical portion 122. The storage portion 24 is formed inside the second cylindrical container 22. The storage portion 24 is in communication with the storage portion 23 of the cylindrical container 13. The second cylindrical container 22 is fixed to the cylindrical container 13 (cylindrical portion 132).

[0052] The second cylindrical container 22 is fixed to the cylindrical part 132 so that the longitudinal direction of the second cylindrical container 22 is perpendicular to the vertical direction. The fixing method is not limited, but for example, the second cylindrical container 22 can be fixed by a joining method described later.

[0053] The shape of the second cylindrical container 22 is not limited, and examples thereof include a cylindrical shape, an elliptical cylindrical shape, a rectangular cylindrical shape, etc. The rectangular cylindrical shape includes a columnar shape in which the cross section of the second cylindrical container 22 in a plane perpendicular to the longitudinal direction of the second cylindrical container 22 is a square, trapezoid, or rectangular shape.

[0054] The thickness of the second cylindrical container 22 is not limited, but is, for example, 2 to 15 mm from the viewpoint of heat insulation and rigidity in the cryogenic temperature range. Depending on the application, the thickness may be the same as that of the cylindrical container 13. Here, the thickness of the second cylindrical container 22 refers to the thickness of the wall of the cylindrical portion 122 constituting the second cylindrical container 22.

[0055] The size of the second cylindrical container 22 is not limited, but for example, when used in a device for measuring the magnetic field of the spinal cord, it is preferable that the second cylindrical container 22 alone is large enough to store 10 to 30 liters of refrigerant.

[0056] Next, the second cylindrical container 22 will be described by dividing it into the cylindrical portion 122 and the bottom portion 123 which constitute the second cylindrical container 22.

[0057] The cylindrical portion 122 is made of FRP, a base material of which is impregnated with resin. The base material constituting the predetermined region of the cylindrical portion 122 includes a woven fabric and a unidirectional fiber sheet. The "predetermined region of the cylindrical portion 122" will be described later.

[0058] The fabric used in the predetermined region of the tubular portion 122 is made by weaving at least one type of fiber selected from the group consisting of glass fiber, alumina fiber, and carbon fiber. From the viewpoints of rigidity retention and processability, the fibers used in the fabric are preferably glass fiber and alumina fiber. The fibers used in the fabric may be composed of two types of fibers. Examples of the weaving method of the fabric include satin weave, plain weave, and twill weave. From the viewpoint of shaping ability, the weaving method is preferably satin weave.

[0059] The unidirectional fiber sheet used in a predetermined region of the tubular portion 122 is composed of at least one type of fiber selected from the group consisting of glass fiber, alumina fiber, and carbon fiber. From the viewpoints of rigidity retention and processability, the fibers used in the unidirectional fiber sheet are preferably glass fiber and alumina fiber. The fibers used in the unidirectional fiber sheet may be composed of two types of fibers.

[0060] The woven fabric and the unidirectional fiber sheet constituting the predetermined region of the tubular portion 122 are laminated, for example, so as to form a part of a tubular shape centered on the axial core of the tubular portion 122. When the cross section of the wall of the tubular portion 122 is viewed in a plane perpendicular to the longitudinal direction of the tubular portion 122, the woven fabric and the unidirectional fiber sheet have a configuration in which the woven fabric is laminated on both sides of the unidirectional fiber sheet, a configuration in which the unidirectional fiber sheet is laminated on both sides of the woven fabric, or a configuration in which the woven fabric and the unidirectional fiber sheet are alternately laminated. From the viewpoint of increasing rigidity, it is preferable that the woven fabric and the unidirectional fiber sheet have a laminated configuration that is line-symmetrical with respect to the woven fabric or the unidirectional fiber sheet that is at the center in the thickness direction when the cross section of the wall of the tubular portion 122 is viewed, for example, a configuration in which the woven fabric is laminated on both sides of the unidirectional fiber sheet with the unidirectional fiber sheet at the center.

[0061] The fibers of the laminated unidirectional fiber sheets are laminated so as to be perpendicular (90°) to the extending direction of the axis of the tubular portion 122. In order not to reduce the rigidity of the tubular portion 122, the inclination range of the fibers of the unidirectional fiber sheets with respect to the extending direction of the axis of the tubular portion 122 is 90°±15°.

[0062] As another configuration of the FRP base material constituting the tubular portion 122, a unidirectional fiber sheet may be laminated between the laminated woven fabrics so that the fibers of the unidirectional fiber sheet are at 90° to the extending direction of the axial core of the tubular portion 122. In this case, the woven fabrics may be laminated, for example, so that the warp threads are at +45° and the weft threads are at -45° to the extending direction of the axial core of the tubular portion 122. Alternatively, the woven fabrics may be laminated so that the warp threads are at 0° and the weft threads are at 90°. From the viewpoint of exhibiting quasi-isotropic rigidity, a configuration may be used in which first, a woven fabric is laminated so that the warp threads are at +45° and the weft threads are at -45° to the extending direction of the axial core of the tubular portion 122, a unidirectional fiber sheet is laminated thereon, and another woven fabric is laminated so that the warp threads are at 0° and the weft threads are at 90° to the extending direction of the axial core of the tubular portion 122.

[0063] FIG. 4 is a BB cross-sectional view of the heat-insulating container 10 shown in FIG. 2. The up-down direction shown in FIG. 4 corresponds to the up-down direction shown in FIG. 1. The inner container 11 (the cylindrical part 122 of the second cylindrical container 22) is surrounded by the outer container 14 via a gap 15. The "predetermined area of ​​the cylindrical part 122" will be described using the cylindrical part 122 having a rectangular cross section shown in FIG. 4 as an example. The predetermined area of ​​the cylindrical part 122 is a partial area of ​​one surface (upper surface) constituting the cylindrical part 122, or the entire area of ​​one surface (upper surface) constituting the cylindrical part 122. For example, when the heat-insulating container 10 is used in a magnetospinometer, the predetermined area of ​​the cylindrical part 122 includes an area facing a measurement surface of a superconducting quantum interference meter.

[0064] The predetermined region of the tubular portion 122 has high rigidity because the base material constituting the predetermined region includes the woven fabric and the unidirectional fiber sheet and has the above-mentioned laminated structure. Furthermore, the predetermined region of the tubular portion 122 including the woven fabric and the unidirectional fiber sheet in the base material has higher rigidity than the predetermined region of the tubular portion 122 including the base material made of only the woven fabric. That is, when the same rigidity as that achieved by a structure made of only the woven fabric is achieved by a structure made of the woven fabric and the unidirectional fiber sheet, the thickness of the wall can be made thinner. Furthermore, when the predetermined region including the woven fabric and the unidirectional fiber sheet in the base material is the entire region of one surface (upper surface) of the tubular portion 122, the proportion of the predetermined region including the woven fabric and the unidirectional fiber sheet in the base material is larger than that of a partial region, and therefore the rigidity is higher.

[0065] When the tubular portion 122 is cylindrical, the predetermined area of ​​the tubular portion 122 is a partial area of ​​the circumferential surface (curved surface) of a semicylinder that constitutes half of a cylinder, or the entire area of ​​the circumferential surface (curved surface) of the semicylinder.

[0066] The configuration of the tubular portion 122 other than the predetermined region may be the same as or different from the configuration of the predetermined region of the tubular portion 122. When it is different, examples of the FRP base material other than the predetermined region include fibers, woven fabrics, and unidirectional fiber sheets. When the base material is a woven fabric, the base material is a laminated structure of woven fabrics. When the base material is a woven fabric and a unidirectional fiber sheet, examples of the base material include a woven fabric laminated on both sides of a unidirectional fiber sheet, a unidirectional fiber sheet laminated on both sides of a woven fabric, or a woven fabric and a unidirectional fiber sheet laminated alternately.

[0067] The amount of resin in the cylindrical portion 122 (converted into solid content) is 15 to 50 wt % with respect to the total weight of the FRP constituting the cylindrical portion 122, from the viewpoint of maintaining rigidity.

[0068] The resin to be impregnated into the base material constituting the cylindrical portion 122 is not limited, and examples thereof include an epoxy resin composition mainly made of an epoxy resin, a phenol resin composition mainly made of a phenol resin, and a polyimide resin composition mainly made of a thermosetting polyimide resin. The resin is preferably an epoxy resin composition from the viewpoint of having rigidity and toughness in the range from room temperature to extremely low temperature, and from the viewpoint of ensuring good processability. The resin may be a mixture of two or more types of resin compositions.

[0069] Next, the bottom surface portion 123 will be described. The bottom surface portion 123 is made of FRP. The base material constituting the FRP is a woven fabric, and is configured by laminating multiple sheets of woven fabric. The resin constituting the FRP is preferably the same as the resin constituting the tubular portion 122, from the viewpoint of making the expansion and contraction behavior of the tubular portion 122 and the bottom surface portion 123 the same in the normal temperature to cryogenic temperature range. The amount of resin in the bottom surface portion 123 (converted into solid content) is preferably 15 to 50 wt % with respect to the total weight of the FRP of the bottom surface portion 123, which is the same as the amount of resin in the tubular portion 122, from the viewpoint of maintaining rigidity.

[0070] The storage section 23 of the cylindrical container 13 and the storage section 24 of the second cylindrical container 22 may be fixed in communication with each other via a member such as a tube. In this case, the member for communicating between the storage section 23 and the storage section 24 is preferably made of the same material as the material constituting the cylindrical container 13 and the second cylindrical container 22.

[0071] A method for producing the second cylindrical container 22 will be described later.

[0072] The joining of the cylindrical container 13 and the second cylindrical container 22 will be described. The joining method is not limited, but examples include a method of applying an adhesive to the joining surface of the cylindrical container 13 and the joining surface of the second cylindrical container 22 and joining them, and a method of forming threads on the joining surface of the cylindrical container 13 and the joining surface of the second cylindrical container 22, applying an adhesive to these threads, and then screwing them together. These joining methods can also be used, for example, to join the cylindrical container 13 and the refrigerant injection tube 12. The joining method is preferably one that can maintain the gap 15 in a vacuum state.

[0073] From the viewpoint of achieving good adhesiveness, the adhesive used is preferably the same resin as that constituting the refrigerant injection tube 12 and the cylindrical container 13. Examples of the resin include an epoxy resin composition mainly made of an epoxy resin, a phenol resin composition mainly made of a phenol resin, or a polyimide resin composition mainly made of a thermosetting polyimide resin. From the viewpoint of having rigidity and toughness in the range from room temperature to extremely low temperature, and from the viewpoint of ensuring good adhesiveness, the resin is preferably an epoxy resin composition. The resin may be a mixture of two or more resin compositions.

[0074] [Outer container 14] As shown in Fig. 3, the outer container 14 is configured to surround the inner container 11 with a gap 15 therebetween. The outer container 14 supports the cylindrical container 13 on the upper surface of the outer container 14 via the refrigerant injection tube 12. In the insulated container 10, the end face of the refrigerant injection tube 12 and the surface of the upper surface of the outer container 14 are on the same plane.

[0075] Here, "surrounding" refers to a state in which the outer container 14 encloses the inner container 11 with a gap 15 therebetween.

[0076] From the viewpoint of improving the heat insulating effect, it is preferable that the gap 15 is in a vacuum state. The outer container 14 has a degree of rigidity that allows the shape of the outer container 14 to be maintained even when the gap 15 is in a vacuum state. The configuration of the outer container 14 will be described below.

[0077] The portion that becomes the upper surface of the outer container 14 is referred to as the “upper surface portion.” The “inside” of the outer container 14 refers to the region of the outer container 14 that contacts the gap 15.

[0078] The shape and size of the outer container 14 are not limited as long as they can surround the inner container 11. From the viewpoint of preventing deformation of the container when the gap 15 is made into a vacuum state, the outer container 14 is preferably configured with a rounded shape capable of dispersing stress. In particular, the corners of the outer container 14 are preferably formed with a shape having a large radius of curvature. This makes it possible to prevent the shrinkage stress on the container caused by the vacuum from concentrating on a specific part of the container.

[0079] The thickness of the wall constituting the outer container 14 is preferably the same as or thicker than the thicknesses of the cylindrical container 13 and the second cylindrical container 22, from the viewpoint of preventing deformation of the container when the space 15 is made into a vacuum state. The wall thickness is, for example, 2 to 30 mm.

[0080] The following describes the FRP that constitutes the outer container 14. The outer container 14 is made of FRP, the base material of which is impregnated with resin.

[0081] The base material constituting a predetermined region of the outer container 14 includes a woven fabric and a unidirectional fiber sheet.

[0082] The fabric used in the predetermined region of the outer container 14 is made by weaving at least one type of fiber selected from the group consisting of glass fiber, alumina fiber, and carbon fiber. The fabric may be made of two types of fiber. From the viewpoints of rigidity retention and processability, the fiber used in the fabric is preferably glass fiber or alumina fiber. Examples of the weaving method of the fabric include satin weave, plain weave, and twill weave. From the viewpoint of shape imparting, the weaving method of the fabric is preferably satin weave.

[0083] The unidirectional fiber sheet used in a predetermined region of the outer container 14 is made of at least one type of fiber selected from the group consisting of glass fiber, alumina fiber, and carbon fiber, which are aligned in one direction. The unidirectional fiber sheet may be made of two types of fiber. From the viewpoints of rigidity retention and processability, the fiber used in the unidirectional fiber sheet is preferably glass fiber or alumina fiber.

[0084] The woven fabric and the unidirectional fiber sheet constituting the predetermined region of the outer container 14 are laminated so as to surround the inner container 11 via a gap 15. When looking at a cross section of the wall constituting the predetermined region of the outer container 14, the woven fabric and the unidirectional fiber sheet have a configuration in which the woven fabric is laminated on both sides of the unidirectional fiber sheet, a configuration in which the unidirectional fiber sheet is laminated on both sides of the woven fabric, or a configuration in which the woven fabric and the unidirectional fiber sheet are alternately laminated. From the viewpoint of increasing rigidity, it is preferable that the woven fabric and the unidirectional fiber sheet are configured to be line-symmetrical with respect to the woven fabric or unidirectional fiber sheet at the center in the thickness direction of the wall constituting the predetermined region of the outer container 14, for example, a configuration in which the woven fabric is laminated on both sides of the unidirectional fiber sheet with the unidirectional fiber sheet at the center.

[0085] From the viewpoint of maintaining the rigidity when the insulating container 10 is used as an insulating container for a magnetospinal meter, the fibers of the unidirectional fiber sheet constituting a predetermined region of the outer container 14 are arranged parallel (0°) to the extending direction of the axis of the second cylindrical container 22 (cylindrical portion 122) surrounded by the outer container 14. From the viewpoint of not decreasing the rigidity of the outer container 14, it is preferable that the fibers of this unidirectional fiber sheet are arranged in the range of 0°±10° to the extending direction of the axis of the second cylindrical container 22 (cylindrical portion 122).

[0086] The woven fabric constituting a predetermined region of the outer container 14 is layered so that the warp threads are at 0° and the weft threads are at 90° with respect to the extending direction of the axis of the second cylindrical container 22 (cylindrical portion 122) surrounded by the outer container 14. The woven fabrics may be layered so that the warp threads are at +45° and the weft threads are at -45°. From the viewpoint of exhibiting quasi-isotropic rigidity, one woven fabric may be layered so that the warp threads are at 0° and the weft threads are at 90°, and another woven fabric may be layered thereon so that the warp threads are at +45° and the weft threads are at -45°.

[0087] As another configuration of the base material constituting the predetermined region of the outer container 14, a unidirectional fiber sheet may be laminated between the woven fabrics. In this case, the woven fabrics may be laminated so that the warp threads are at +45° and the weft threads are at -45° with respect to the extending direction of the axis of the second cylindrical container 22 (cylindrical part 122) surrounded by the outer container 14. Alternatively, the woven fabrics may be laminated so that the warp threads are at 0° and the weft threads are at 90°. From the viewpoint of maintaining the rigidity when the insulating container 10 is used as an insulating container for a magnetospinometer, the fibers of the unidirectional fiber sheet are arranged so as to be at 90° with respect to the extending direction of the axis of the surrounding second cylindrical container 22 (cylindrical part 122).

[0088] The "predetermined area of ​​the outer container 14" will be described using as an example the outer container 14 in the shape of a rectangular cylinder with a square cross section shown in Fig. 4. The outer container 14 is disposed so as to surround the inner container 11 (the cylindrical portion 122 of the second cylindrical container 22) via a gap 15. If the entire area of ​​the top surface (one surface) constituting the cylindrical portion 122 is defined as the predetermined area of ​​the cylindrical portion 122, then the area of ​​the top surface constituting the outer container 14 above that is the predetermined area of ​​the outer container 14.

[0089] A predetermined area of ​​the outer container 14 and a predetermined area of ​​the inner container 11 (cylindrical portion 122) each contain a unidirectional fiber sheet in the base material constituting the predetermined area. The outer container 14 surrounds the inner container 11 (cylindrical portion 122) so that the unidirectional fiber sheet of the cylindrical portion 122 and the unidirectional fiber sheet of the outer container 14 face each other. With this configuration, the predetermined area of ​​the outer container 14 and the predetermined area of ​​the cylindrical portion 122 can withstand external stress even if the gap 15 is in a vacuum state.

[0090] A predetermined region of the outer container 14 and a predetermined region of the tubular portion 122 whose base material includes a woven fabric and a unidirectional fiber sheet have higher rigidity than a predetermined region of the outer container 14 and a predetermined region of the tubular portion 122 whose base material includes only a woven fabric. In other words, when the same rigidity as that achieved by a configuration including only a woven fabric is to be achieved by a configuration including a woven fabric and a unidirectional fiber sheet, the wall thickness of the tubular portion 122 and the corresponding wall thickness of the outer container 14 can be made thinner.

[0091] It is preferable that the predetermined area of ​​the outer container 14 is larger than the predetermined area of ​​the cylindrical portion 122. This improves the rigidity of the predetermined area of ​​the outer container 14 and enables it to withstand external stress.

[0092] The configuration of the outer container 14 other than the predetermined region may be the same as or different from the configuration of the predetermined region of the outer container 14. In the case where it is different, examples of the FRP base material other than the predetermined region include fibers, woven fabrics, unidirectional fiber sheets, etc. When the base material is a woven fabric, the base material is a laminated structure of woven fabrics. When the base material is a woven fabric and a unidirectional fiber sheet, examples of the base material include a laminated structure of woven fabrics on both sides of a unidirectional fiber sheet, a laminated structure of unidirectional fiber sheets on both sides of a woven fabric, or a laminated structure of woven fabrics and unidirectional fiber sheets alternately.

[0093] The resin to be impregnated into the base material constituting the outer container 14 is not limited, and examples thereof include an epoxy resin composition mainly made of an epoxy resin, a phenol resin composition mainly made of a phenol resin, and a polyimide resin composition mainly made of a thermosetting polyimide resin. From the viewpoint of having rigidity and toughness in the range from room temperature to extremely low temperature, and from the viewpoint of ensuring good processability, the resin to be impregnated into the base material constituting the outer container 14 is preferably an epoxy resin composition. The resin may be a mixture of two or more resin compositions.

[0094] The resin amount (solid content equivalent) of the outer container 14 is preferably 15 to 50 wt % with respect to the total weight of the FRP of the outer container 14, from the viewpoint of maintaining the rigidity of the outer container 14 when storing a refrigerant at -196°C or lower.

[0095] The gap 15 between the outer container 14 and the cylindrical container 13, and the gap 15 between the outer container 14 and the second cylindrical container 22 may be provided with supports (not shown) that support the cylindrical container 13 and the second cylindrical container 22 in order to support the load and fix the cylindrical container 13 and the second cylindrical container 22 in fixed positions.

[0096] A method for producing the outer container 14 will be described later.

[0097] The joining of the outer container 14 and the refrigerant injection tube 12 will be described. Examples of joining methods include a method of applying an adhesive to the joining surface of the outer container 14 and the joining surface of the refrigerant injection tube 12 and joining them, and a method of forming a thread on the joining surface of the outer container 14 and the joining surface of the refrigerant injection tube 12, applying an adhesive, and then screwing them together. These joining methods can also be used, for example, when joining the members that make up the outer container 14 together.

[0098] Another configuration of the cylindrical container 13 is a cylindrical container 13 in which the wall of the cylindrical portion 132 has a two-layer structure. As shown in circle 1 in Fig. 8, the wall of the cylindrical portion 132 is composed of an outer layer 141 and an inner layer 142. The outer layer 141 constitutes a layer close to the void 15 (outside), and the inner layer 142 constitutes a layer close to the refrigerant 16 (inside).

[0099] The outer layer 141 and the inner layer 142 are made of FRP. The fibers that make up the FRP are glass fibers or alumina fibers.

[0100] The fibers constituting the outer layer 141 and the inner layer 142 are each wound in a spiral shape with respect to the extension direction of the axial core of the tubular portion 132. The inclination of the fibers with respect to the extension direction of the axial core of the tubular portion 132 may be different or the same between the outer layer 141 and the inner layer 142. From the viewpoint of increasing the rigidity of the tubular portion 132 and improving workability (ease of demolding from a mold), it is preferable that the angle that the fibers constituting the inner layer 142 make with respect to the extension direction of the axial core is larger than the angle that the fibers constituting the outer layer 141 make.

[0101] From the viewpoints of ensuring the rigidity of the cylindrical portion 132, slowing down the conduction of heat from the outside to the entire inner container 11 via the refrigerant injection tube 12, and reducing costs, the fibers constituting the outer layer 141 are preferably glass fibers. The fibers constituting the inner layer 142 are preferably alumina fibers.

[0102] It is preferable that the thickness of outer layer 141 and inner layer 142 are the same or that inner layer 142 is thicker than outer layer 141. The ratio of the thickness of inner layer 142 to the thickness of outer layer 141 is 50:50 to 80:20, preferably 50:50 to 70:30, and more preferably 50:50 to 60:40.

[0103] From the viewpoint of preventing delamination between layers, it is preferable that the resin constituting outer layer 141 and the resin constituting inner layer 142 are the same resin.

[0104] From the viewpoint of slowing down the conduction of heat from the outside to the entire inner container 11 via the refrigerant injection pipe 12, when the FRP configuration of the tubular part 132 is a two-layer configuration, it is preferable that the FRP configuration of the top surface part 131 and the bottom surface part 133 is also a two-layer configuration. It is also preferable that the fiber configuring the outer layer 141 is glass fiber, and the fiber configuring the inner layer 142 is alumina fiber. It is also preferable that the thicknesses of the outer layer 141 and the inner layer 142 are the same or that the inner layer 142 is thicker than the outer layer 141.

[0105] The method for producing the two-layer structure will be explained in the method for producing the cylindrical container 13.

[0106] Hereinafter, methods for manufacturing the refrigerant injection tube 12, the cylindrical container 13, the second cylindrical container 22, and the outer container 14 will be described.

[0107] [Method of manufacturing the refrigerant injection tube 12] A manufacturing method for refrigerant injection tube 12 includes, for example, a molding process in which a fiber impregnated with liquid resin is spirally wound around a rod-shaped mold to form the shape of refrigerant injection tube 12, a hardening process in which the resin is hardened by heating, and a demolding process in which the hardened refrigerant injection tube 12 is removed from the mold.

[0108] In the molding step, for example, a filament winding method can be used to mold refrigerant injection pipe 12. The angle at which the fibers are wound around the mold is 50 to 89° with respect to the extension direction of the axis of the mold.

[0109] In the curing step, the temperature and time for curing the resin can be appropriately set depending on the type of resin, the amount of resin, etc. For example, when an epoxy resin composition is used as the resin and the amount of resin is 20 to 50 wt%, the temperature is 80 to 150° C. and the time is 1 to 12 hours.

[0110] In the demolding step, the mold is cooled to room temperature and refrigerant injection tube 12 is removed from the mold. Then, refrigerant injection tube 12 is obtained.

[0111] [Method of manufacturing the cylindrical container 13] A method for manufacturing the cylindrical container 13 will be described. The cylindrical portion 132 of the cylindrical container 13 is obtained by manufacturing it in the same manner as the above-mentioned method for manufacturing the refrigerant injection tube 12. The top surface portion 131 and the bottom surface portion 133 of the cylindrical container 13 are obtained by stacking a plurality of prepregs in which a woven fabric is impregnated with a resin, curing them, and cutting them into a predetermined shape. Here, the prepreg refers to a composite material in which a woven fabric is impregnated with a resin and the cured state of the resin is in a B-stage state. The B-stage state refers to a state in which the resin is not completely cured. Instead of the woven fabric, a unidirectional fiber sheet or a prepreg in which fibers are impregnated with a resin may be used.

[0112] A method for joining the cylindrical portion 132 to the top surface portion 131 and the bottom surface portion 133 will be described.

[0113] The joining method is not limited, but for example, a screw may be formed at the joining portion between the top surface portion 131 and the cylindrical portion 132, and at the joining portion between the bottom surface portion 133 and the cylindrical portion 132. Also, by applying an adhesive or the like that hardens at room temperature to the screw before screwing, the joining portion can be reliably sealed.

[0114] Another manufacturing method for the cylindrical container 13 includes, for example, a prepreg production process in which a woven fabric is impregnated with resin and then heated to produce a prepreg, a molding process in which the prepreg is attached to the surface of a mold having the shape of the cylindrical container 13 and molded, a curing process in which the prepreg is cured by heating and pressurizing, and a demolding process in which the cured prepreg is removed from the mold.

[0115] In the prepreg production process, the time for impregnating the woven fabric with the resin and the temperature of the resin to be impregnated can be appropriately set depending on the type of resin, the amount of resin attached (amount of resin), etc. For example, when an epoxy resin composition is used as the resin and the amount of resin is 20 to 50 wt%, the temperature is 80 to 150°C and the time is 1 to 12 hours.

[0116] In the molding process, the produced prepreg is cut to a predetermined size. If the shape of the mold is complicated, the prepreg is cut into small pieces. This allows the prepreg to conform to the complicated shape.

[0117] In the curing step, the molded prepreg can be cured, for example, by autoclave molding using a high-pressure cooker, which allows the prepreg to be cured uniformly.

[0118] In the demolding step, the cured prepreg is cooled to room temperature and then removed from the mold, thereby obtaining a cylindrical container 13.

[0119] Furthermore, when the tubular portion 132 is made of FRP having a two-layer structure, the tubular portion 132 having a two-layer structure can be produced by a filament winding method.

[0120] For example, when the fibers constituting the inner layer are alumina fibers and the fibers constituting the outer layer are glass fibers, they are produced as follows. Alumina fibers impregnated with resin are wound in a spiral shape around a rod-shaped die. Next, glass fibers impregnated with resin are wound in a spiral shape around the wound alumina fibers to form the shape of the tubular portion 132. After that, the resin is hardened by heating. After cooling to room temperature, it is removed from the die to obtain the tubular portion 132 having a two-layer structure.

[0121] When the tubular portion 132 is a two-layer FRP, the manufacturing method of the top surface portion 131 and the bottom surface portion 133, the joining method of the top surface portion 131 and the tubular portion 132, and the joining method of the bottom surface portion 133 and the tubular portion 132 can be the same as the manufacturing method of the top surface portion 131 and the bottom surface portion 133, the joining method of the top surface portion 131 and the tubular portion 132, and the joining method of the bottom surface portion 133 and the tubular portion 132 described above.

[0122] The top surface portion 131 and the bottom surface portion 133 are also preferably configured as a two-layer structure consisting of a layer made of alumina fiber and a layer made of glass fiber. In this case, the top surface portion 131 and the bottom surface portion 133 are manufactured using a woven fabric prepreg woven from alumina fiber and a woven fabric prepreg woven from glass fiber.

[0123] [Method of manufacturing the second cylindrical container 22] A method for manufacturing the second cylindrical container 22 will be described. The method for manufacturing the second cylindrical container 22 includes, for example, a prepreg manufacturing step of manufacturing a cross prepreg using a woven fabric as a base material and a UD prepreg using a unidirectional fiber sheet as a base material, a cross prepreg molding step of attaching the cross prepreg to the surface of a mold shaping the cylindrical portion 122 so that the direction of the warp or weft is perpendicular to the extending direction of the axial core of the mold, a UD prepreg molding step of attaching the UD prepreg to the cross prepreg so that the fibers of the unidirectional fiber sheet are perpendicular to the extending direction of the axial core of the mold, a cross prepreg second molding step of attaching the cross prepreg to the laminated prepreg so that the direction of the warp or weft of the woven fabric is perpendicular to the extending direction of the axial core of the mold, a curing step of curing the laminated prepreg by heating and pressurizing, and a demolding step of removing the cured prepreg from the mold.

[0124] In the prepreg production process, the time for impregnating the woven fabric or unidirectional fiber sheet with the resin and the temperature of the resin during impregnation can be appropriately set depending on the type of resin and the amount of resin attached (amount of resin), etc. For example, when an epoxy resin composition is used as the resin and the amount of resin is 20 to 50 wt%, the temperature is 80 to 150°C and the time is 1 to 12 hours.

[0125] In the cross prepreg molding step, the produced cross prepreg is cut to a predetermined size and attached so that the warp or weft yarns constituting the cross prepreg are perpendicular to the extending direction of the axial core of the mold.

[0126] In the UD prepreg molding process, the produced UD prepreg is attached onto the cross prepreg so that the fibers of the unidirectional fiber sheet are perpendicular to the extending direction of the axial core of the mold. The region where the UD prepreg is attached onto the cross prepreg may be a region that corresponds to at least a predetermined region in the tubular portion 122. From the viewpoint of increasing the rigidity of the tubular portion 122, the UD prepreg may be attached onto the entire tubular portion 122.

[0127] In the second cross prepreg molding process, the cross prepreg cut to a predetermined size is applied to the surface of the prepreg applied in the previous process so that the warp or weft threads are perpendicular to the extension direction of the axis of the mold.

[0128] In the curing step, the molded prepreg can be cured, for example, by autoclave molding using a high-pressure cooker, which allows the prepreg to be cured uniformly.

[0129] In the demolding step, the cured prepreg is cooled to room temperature and then removed from the mold, thereby obtaining the cylindrical portion 122.

[0130] The bottom surface portion 123 is obtained by stacking a plurality of prepregs, which are fabrics impregnated with resin, curing them, and cutting them into a predetermined shape. The bottom surface portion 123 and the cylindrical portion 122 can be screwed together by forming a thread at the joint between the bottom surface portion 123 and the cylindrical portion 122. In addition, the joint can be reliably sealed by applying an adhesive or the like that cures at room temperature to the thread before screwing.

[0131] [Method of manufacturing outer container 14] The manufacturing method of the outer container 14 will be explained separately into a manufacturing method of the outer container 14 surrounding the second cylindrical container 22 and a manufacturing method of the outer container 14 surrounding the other inner containers 11.

[0132] The manufacturing method of the outer container 14 surrounding the second cylindrical container 22 includes a prepreg production step of producing a cross prepreg based on a woven fabric and a UD prepreg based on a unidirectional fiber sheet, a cross prepreg molding step of attaching and molding the cross prepreg to the surface of a mold shaped to form the outer container 14 surrounding the second cylindrical container 22 so that the direction of the warp or weft is parallel to the extending direction of the axial core of the mold, a UD prepreg molding step of attaching and molding a UD prepreg on the cross prepreg so that the fibers of the unidirectional fiber sheet are parallel to the extending direction of the axial core of the mold, a second cross prepreg molding step of attaching and molding a cross prepreg on the stacked prepregs so that the direction of the warp or weft is parallel to the extending direction of the axial core of the mold, a curing step of curing the stacked prepregs by heating and pressurizing, and a demolding step of removing the cured prepregs from the mold.

[0133] In the prepreg production process, the time for impregnating the woven fabric or unidirectional fiber sheet with the resin and the temperature of the resin can be appropriately set depending on the type of resin, the amount of resin attached (amount of resin), etc. For example, when an epoxy resin composition is used as the resin and the amount of resin is 20 to 50 wt%, the temperature is 80 to 150°C and the time is 1 to 12 hours.

[0134] In the cross prepreg molding step, the fabricated cross prepreg is cut to a predetermined size and attached so that the direction of the warp or weft is parallel to the extending direction of the axis of the mold.

[0135] In the UD prepreg molding process, the produced UD prepreg is attached onto the cross prepreg so that the fibers of the unidirectional fiber sheet are parallel to the extension direction of the axial core of the mold. The area where the UD prepreg is attached onto the cross prepreg may be an area that corresponds to at least a predetermined area of ​​the outer container 14. From the viewpoint of increasing the rigidity of the outer container 14, the UD prepreg may be attached onto the entire outer container 14.

[0136] In the second cross prepreg molding process, the cross prepreg cut to a predetermined size is attached to the surface of the prepreg attached in the previous process so that the warp or weft yarns are parallel to the extension direction of the axis of the mold.

[0137] In the curing step, the molded prepreg can be cured, for example, by autoclave molding using a high-pressure cooker, which allows the prepreg to be cured uniformly.

[0138] In the demolding step, the cured prepreg is cooled to room temperature and then removed from the mold, yielding the outer container 14.

[0139] The outer container 14 surrounding the bottom portion 123 via the gap 15 is obtained by stacking a plurality of prepregs made of woven fabric impregnated with resin, hardening them, and cutting them into a predetermined shape. The outer container 14 surrounding the bottom portion 123 via the gap 15 and the outer container 14 surrounding the second cylindrical container 22 are screwed together by forming threads at their joints. In addition, the joints can be reliably sealed by applying an adhesive or the like that hardens at room temperature to the threads before screwing them together.

[0140] The manufacturing method of the outer container 14 which surrounds the inner container 11 other than the second cylindrical container 22 and the bottom portion 123 via the gap 15 includes a prepreg production process in which a woven fabric is impregnated with resin and then heated to produce a prepreg, a prepreg molding process in which the prepreg is attached to the surface of a mold shaped to form the outer container 14 which surrounds the inner container 11 other than the second cylindrical container 22 and the bottom portion 123 via the gap 15, a curing process in which the prepreg is cured by heating and pressurizing, and a demolding process in which the cured prepreg is removed from the mold.

[0141] In the prepreg production process, the time for impregnating the woven fabric with the resin and the temperature of the resin to be impregnated can be appropriately set depending on the type of resin and the amount of resin attached to the woven fabric (amount of resin), etc. For example, when an epoxy resin composition is used as the resin and the amount of resin is 20 to 50 wt%, the temperature is 80 to 160°C and the time is 1 to 12 hours.

[0142] In the prepreg forming process, the produced prepreg is cut to a predetermined size.

[0143] In the curing step, the molded prepreg can be cured, for example, by autoclave molding using a high-pressure cooker, which allows the prepreg to be cured uniformly.

[0144] In the demolding step, the cured prepreg is cooled to room temperature and then removed from the mold, thereby obtaining an outer container 14 that surrounds the second cylindrical container 22 and the inner container 11 except for the bottom portion 123 via a gap 15.

[0145] The outer container 14 surrounding the bottom portion 123, the outer container 14 surrounding the second cylindrical container 22, and the outer container 14 surrounding the other inner containers 11 are, for example, screwed together by forming threads at their joints. Also, by applying an adhesive or the like that hardens at room temperature to the threads before screwing them together, the joints can be reliably sealed.

[0146] [Application example 1] An example of an application of the heat-insulating container 10 according to the first embodiment is a magnetospinograph 60.

[0147] As shown in FIG. 9, the spinal magnetometer 60 includes a superconducting quantum interferometer 17 for detecting a magnetic field generated from a living body 18, and an insulating container 10. The insulating container 10 includes an inner container 11 and an outer container 14 surrounding the inner container 11 via a gap 15. The inner container 11 includes a cylindrical container 13 having a container section 23 for storing a refrigerant 16 therein, a refrigerant injection tube 12 attached to the cylindrical container 13, and a second cylindrical container 22 having a container section 24 for storing the refrigerant 16 therein. The superconducting quantum interferometer 17 is stored in a state of being immersed in the refrigerant 16 stored in the second cylindrical container 22. The living body 18 is laid down so that the spinal cord of the living body 18 is located on the measurement surface 19 of the superconducting quantum interferometer 17 as shown in FIG. 9.

[0148] 9, the measurement surface 19 faces the unidirectional fiber sheet 61 constituting a predetermined region of the outer container 14, and faces the unidirectional fiber sheet 62 constituting a predetermined region of the second cylindrical container 22 (cylindrical portion 122). The fibers of the unidirectional fiber sheet 61 are parallel to the extension direction of the axis of the second cylindrical container 22. The fibers of the unidirectional fiber sheet 62 are perpendicular to the extension direction of the axis of the second cylindrical container 22.

[0149] [effect] The heat-insulating container 10 according to the above-described first embodiment and the magnetospinograph 60 using the heat-insulating container 10 provide the following advantages.

[0150] Since the fibers of the unidirectional fiber sheet 61 are arranged parallel to the extending direction of the axis of the second cylindrical container 22, it can support the weight even if the spinal cord of the living body 18 is located above a predetermined region of the outer container 14. Moreover, since the fibers of the unidirectional fiber sheet 62 are arranged perpendicular to the extending direction of the axis of the second cylindrical container 22, the predetermined region of the second cylindrical container 22 has enough rigidity to withstand the internal pressure caused by the gap 15 being in a vacuum state.

[0151] Furthermore, since the predetermined area of ​​the second cylindrical container 22 and the predetermined area of ​​the outer container 14 are configured as described above, the insulated container 10 has high rigidity. This allows the thickness of the wall to be relatively thin. That is, the magnetospinometer 60 using the insulated container 10 can shorten the distance (lift-off) from the measurement surface 19 to the spinal cord (measurement site) of the living body 18.

[0152] Furthermore, the insulated container 10 equipped with the refrigerant injection pipe 12 can slow down the transfer of heat from the outside to the inner container 11 via the refrigerant injection pipe 12. This allows the refrigerant to be stored in the insulated container 10 for a long period of time. EXAMPLES

[0153] The strength and elastic modulus of the following examples and comparative examples were measured in order to evaluate the rigidity of the insulated container 10. Note that the present invention is not limited in any way to the following examples.

[0154] The resins and substrates used in the examples and comparative examples are as follows.

[0155] (resin) (1) Matrix resin A (1-1) Base resin: bisphenol A type epoxy resin (Dow Chemical Company, DER383LCL), (1-2) Curing agent: acid anhydride curing agent (Hitachi Chemical Co., Ltd., HN-2000), (1-3) Curing accelerator: N,N-dimethylbenzylamine (Kao Corporation, Kaolizer No. 20).

[0156] (2) Matrix resin B (2-1) Base resin: bisphenol A type epoxy resin (DIC Corporation, EPICLON850), (2-2) Hardener: Amine-based hardener (DICY, manufactured by Nippon Carbide Industries Co., Ltd.), (2-3) Curing accelerator: N,N- Dimethylbenzylamine (Kao Corporation, Kaolizer No. 20).

[0157] (base material) (1) Glass cloth (K7628, manufactured by Arisawa Fiberglass Co., Ltd.), (2) Unidirectional fiber sheet using alumina fiber (Arisawa Fiberglass, ECC181).

[0158] A resin was prepared for impregnating the substrate. (1) Preparation of resin (1-1) Preparation of resin for use in prepregs based on textile fabrics The base resin, curing agent, and curing accelerator for matrix resin A were used. First, 100 parts by weight of the base resin, 88 parts by weight of the curing agent, and 0.8 parts by weight of the curing accelerator were added to a container. After that, it was stirred at room temperature, 700 rpm, and 60 minutes with a high-speed mixer to obtain matrix resin A. The viscosity at this time was 500 mPa s.

[0159] (1-2) Preparation of resin for prepreg based on unidirectional fiber sheet The base resin, curing agent, and curing accelerator for matrix resin B were used. First, 100 parts by weight of the base resin, 88 parts by weight of the curing agent, and 0.8 parts by weight of the curing accelerator were added to a container. After that, it was stirred at room temperature, 700 rpm, and 60 minutes with a high-speed mixer to obtain matrix resin B. The viscosity at this time was 500 mPa s.

[0160] The prepared resin was used to make a prepreg. (2) Prepreg Preparation (2-1) Preparation of cloth prepreg using woven fabric (glass cloth) as a base material The glass cloth was impregnated with matrix resin A so that the amount of resin after curing was 35 wt %. Next, it was dried at 130°C for 10 minutes to obtain a prepreg in a B-stage state with a resin amount of 35 wt %.

[0161] (2-2) Fabrication of cloth prepreg using fabric (glass cloth) with different resin content as a base material To prepare prepregs with resin amounts of 13, 15, 18, 40, 50, and 60 wt% after curing, each glass cloth was impregnated with matrix resin A. Next, the impregnated glass cloth was dried at 130°C for 10 minutes to obtain prepregs in a B-stage state with resin amounts of 13, 15, 18, 40, 50, and 60 wt%.

[0162] (2-3) Preparation of UD prepreg using unidirectional fiber sheet (UD) as a base material The UD was impregnated with matrix resin B so that the amount of resin after curing was 35 wt%. Next, it was dried at 130°C for 10 minutes to obtain a UD prepreg in a B-stage state with a resin amount of 35 wt%.

[0163] In the examples and comparative examples, the preparation of measurement samples, and the methods of measurement and evaluation were as follows.

[0164] (3) Preparation of measurement samples (3-1) Preparation of measurement samples with different laminated structures and the same amount of resin First, the prepregs (2-1) and (2-3) prepared above were laminated according to the lamination configurations of Examples 1 to 6, Comparative Example 1, and Comparative Example 2 shown in Tables 1 and 2. The cross prepregs were laminated with one side of an arbitrary prepreg as a reference, and the angle between the warp yarn and that side was set to 0°. The UD prepregs were laminated with the angle between the aligned fibers and the reference side set to a predetermined angle. Here, the predetermined angle was 0° in Examples 1 to 3, and 90° in Examples 4 to 6. The laminated prepregs were pressed under conditions of 130°C, 90 minutes, and 0.29 MPa so that the amount of resin after curing was 35 wt% and the thickness after curing was 2.5 mm. After pressing, a sample in a C-stage state was obtained.

[0165] The measurement samples of Examples 1 to 6 were cut from the obtained samples of Examples 1 to 6 into a rectangle having a width of 10 mm and a length of 20 mm, so that the orientation direction of the fibers of the UD prepreg was parallel to the length direction. The measurement samples of Comparative Examples 1 and 2 were cut from the obtained samples of Comparative Examples 1 and 2 into a rectangle having a width of 10 mm and a length of 20 mm, so that the warp threads of the woven fabric were parallel to the length direction. The measurement samples of Examples 4 to 6 were cut into a rectangle having a width of 10 mm and a length of 20 mm, so that the orientation direction of the fibers of the UD prepreg was parallel to the length direction of the measurement samples, in order to evaluate the difference in effect (rigidity) due to the difference in the orientation direction of the fibers when the unidirectional fiber sheet was used for a heat-insulating container (particularly an inner container).

[0166] (3-2) Preparation of measurement samples with the same laminate structure but different resin amounts Each prepreg set to a predetermined resin amount (2-2) was laminated so that the thickness after curing was 2.5 mm so as to obtain the resin amount of Examples 7 to 10, Comparative Example 3, and Comparative Example 4 shown in Table 3. The prepregs were laminated so that the warp threads were parallel to one side of an arbitrary prepreg as a reference. The prepregs after lamination were pressed under conditions of 130°C, 90 minutes, and 0.29 MPa to obtain samples in a C-stage state with different resin amounts. Furthermore, a measurement sample was cut from the obtained sample into a rectangle with a width of 10 mm and a length of 20 mm so that the warp threads of the woven fabric were parallel to the length direction.

[0167] (4) Measurement of bending strength and bending modulus The bending strength and bending modulus were measured using an autograph testing machine (AG-10, manufactured by Shimadzu Corporation). The measurements were performed by three-point bending (support distance 10 mm, test speed 2 mm / min). When performing the measurements, the measurement sample was placed on the testing machine so that the supports at both ends of the three-point bending were located at both ends in the longitudinal direction of the measurement sample. The bending strength and bending modulus were calculated from the obtained maximum bending stress (breaking load) in accordance with JIS K7017.

[0168] Tables 1 and 2 show the results of bending strength and bending modulus of elasticity in Examples 1 to 6, Comparative Example 1, and Comparative Example 2. Table 3 shows the results of bending strength and bending modulus of elasticity in Examples 7 to 10, Comparative Example 3, and Comparative Example 4, depending on the resin amount.

[0169] [Table 1]

[0170] [Table 2]

[0171] [Table 3]

[0172] Comparing the Examples and Comparative Examples shown in Table 1, it was found that, when the thickness was the same, the bending strength of Example 1 was about 1.2 times that of Comparative Example 1. Furthermore, it was found that the bending strength of Example 3 was about 1.4 times that of Comparative Example 1. It was also found that the bending modulus of Example 1 was about 1.4 times that of Comparative Example 1. It was also found that the bending modulus of Example 2 was about 2.2 times that of Comparative Example 1.

[0173] Comparing the Examples and Comparative Examples shown in Table 2, it was found that, when the thickness was the same, the bending strength of Example 4 was about 1.2 times that of Comparative Example 2. Furthermore, it was found that the bending strength of Example 6 was about 1.4 times that of Comparative Example 2. Furthermore, it was found that the bending modulus of Example 4 was about 1.4 times that of Comparative Example 2. Furthermore, it was found that the bending modulus of Example 5 was about 2.2 times that of Comparative Example 2.

[0174] Comparing Examples 7 to 10 and Comparative Example 4 shown in Table 3, it was found that by increasing the resin amount to 15 to 50 wt%, the bending strength was increased by about 1.3 to 1.7 times, and the bending modulus was increased by about 2.0 to 2.5 times.

[0175] From these results, for example, in order to achieve the same rigidity as in Example 1 with the configuration of Comparative Example 1, it is necessary to further increase the thickness of Comparative Example 1. That is, with the configuration of Example 1, it is possible to provide an insulated container with a thin wall thickness and high rigidity. Such an insulated container is preferable as an insulated container for an outer container that is easily affected by external pressure (external air pressure) and external stress due to load. Also, with the configuration of Comparative Example 2, in order to achieve the same rigidity as in Example 4, it is necessary to further increase the thickness of Comparative Example 2. That is, with the configuration of Example 4, it is possible to provide an insulated container with a thin wall thickness and high rigidity. Such an insulated container is preferable as an insulated container for an inner container that is easily affected by stress due to internal pressure. Also, from the results of Table 3, it is possible to increase the strength and elastic modulus of the insulated container itself by setting the resin amount to 15 to 50 wt%. That is, it is possible to increase the rigidity of the insulated container itself.

[0176] From the above results, it is possible to provide an insulating container having a thin wall and high rigidity, and a magnetospinometer using the same, with the configuration of the embodiment.

[0177] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. The above-described embodiments are for the purpose of explaining the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is indicated by the claims, not the embodiments. Various modifications made within the scope of the claims and within the scope of the meaning of the invention equivalent thereto are considered to be within the scope of the present invention.

[0178] This application is based on Japanese Patent Application No. 2021-059358, filed on March 31, 2021. The specification, claims, and drawings of Japanese Patent Application No. 2021-059358 are incorporated herein by reference in their entirety. [Explanation of symbols]

[0179] 10 Insulated container, 11 Inner container, 12 Refrigerant injection pipe, 13 Cylindrical containers, 131 Top part, 122, 132 cylindrical portion, 123, 133 bottom part, 141 outer layer, 142 inner layer, 14 Outer container, 15 void, 16 Refrigerants, 17 Superconducting quantum interference 18 Living organisms, 19 Measurement surface, 21 Base material, 22 a second cylindrical container, 23, 24 Storage section, 60 magnetospinometer, 61, 62 Unidirectional fiber sheet, 65 Stopper thread, 66 Flat thread.

Claims

1. The container has an inner container and an outer container surrounding the inner container via a gap, The inner container and the outer container are made of fiber-reinforced plastic in which a base material containing fiber is impregnated with resin, the inner container comprises a cylindrical container and a second cylindrical container each having a storage portion for storing a refrigerant therein, and a refrigerant injection pipe for injecting the refrigerant into the cylindrical container; The second cylindrical container includes a cylindrical portion having a horizontal axis and a bottom portion that closes one end of the cylindrical portion, The second cylindrical container has a storage portion that communicates with the storage portion of the cylindrical container, The base material constituting the predetermined region of the second cylindrical container and the predetermined region of the outer container includes a woven fabric and a unidirectional fiber sheet formed by aligning a plurality of fibers in one direction, The base material constituting the predetermined region of the second cylindrical container has a configuration in which a woven fabric is laminated on both sides of a unidirectional fiber sheet, a configuration in which a unidirectional fiber sheet is laminated on both sides of a woven fabric, or a configuration in which a woven fabric and a unidirectional fiber sheet are alternately laminated, The base material constituting the predetermined region of the outer container has a configuration in which a woven fabric is laminated on both sides of a unidirectional fiber sheet, a configuration in which a unidirectional fiber sheet is laminated on both sides of a woven fabric, or a configuration in which a woven fabric and a unidirectional fiber sheet are alternately laminated, a base material constituting the portion of the second cylindrical container other than the predetermined region and the portion of the outer container other than the predetermined region includes a woven fabric and a unidirectional fiber sheet, and has a structure in which the woven fabric is laminated, a structure in which the woven fabric is laminated on both sides of the unidirectional fiber sheet, a structure in which the unidirectional fiber sheet is laminated on both sides of the woven fabric, or a structure in which the woven fabric and the unidirectional fiber sheet are alternately laminated; a heat-insulating container, the outer container surrounding the second cylindrical container in a state in which the unidirectional fiber sheet constituting the predetermined region of the second cylindrical container and the unidirectional fiber sheet constituting the predetermined region of the outer container face each other; A superconducting quantum interference meter for detecting a magnetic field generated from a living body, the superconducting quantum interference meter is accommodated in a state of being immersed in a refrigerant stored in the accommodation portion of the second cylindrical container, a measurement surface of the superconducting quantum interference meter faces the predetermined area of ​​the outer container and the predetermined area of ​​the second cylindrical container; the predetermined region of the second cylindrical container is a predetermined region of the cylindrical portion facing a measurement surface of the superconducting quantum interference meter, A magnetospinometer, wherein the predetermined region of the outer container is a region to which the weight of a living body that is a target for magnetic field detection is applied.

2. 2. The magnetospinograph according to claim 1, wherein the fibers of the unidirectional fiber sheet constituting the predetermined region of the second cylindrical container are perpendicular to the extending direction of the axis of the second cylindrical container.

3. 3. The magnetospinograph according to claim 1, wherein the fibers of the unidirectional fiber sheet constituting the predetermined region of the outer container are parallel to an extending direction of an axis of the second cylindrical container.

4. 4. The spinal cord magnetometer according to claim 1, wherein the woven fabric and the unidirectional fiber sheet constituting the predetermined region of the second cylindrical container are made of at least one material selected from the group consisting of glass fiber, alumina fiber, and carbon fiber.

5. 5. The magnetospinometer according to claim 1, wherein the woven fabric and the unidirectional fiber sheet constituting the predetermined region of the outer container are made of at least one material selected from the group consisting of glass fiber, alumina fiber, and carbon fiber.

6. 6. The magnetospinograph according to claim 1, wherein the amount of resin in the fiber reinforced plastic constituting the insulating container is 15 to 50 wt % with respect to the total weight of the fiber reinforced plastic.

7. The magnetospinometer according to claim 1 , wherein the resin comprises an epoxy resin.

Images