Method for manufacturing liquefied gas containers, and liquefied gas containers

Abstract

To obtain a liquefied gas container which is light in weight, excellent in heat resistance, and is suitable for storing liquid having strong oxidation.SOLUTION: A method of manufacturing a liquefied gas container has: an inside vessel forming step of pasting a thermoplastic prepreg 52 composed of a fiber-reinforced thermoplastic resin to an outer surface of an inside vessel forming mandrel 50, and forming an inside vessel 14; an outside vessel constitution piece forming step of pasting the thermoplastic prepreg 52 to an outer surface of an outside vessel forming mandrel 70, and forming a cylinder portion 12A for constituting an outside vessel 12 which is larger than the inside vessel 14, and a pair of mirror portions 12B; an outside vessel forming step of arranging the cylinder portion 12A and a pair of the mirror portions 12B at the outside of the inside vessel 14, connecting the cylinder portion 12A and the mirror portions 12B, also connecting the inside vessel 14 and the mirror portions 12B by a boss 16, and forming the outside vessel 12 at the outside of the inside vessel 14; and a vacuum step of vacuuming a space between the inside vessel 14 and the outside vessel 12.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a liquefied gas container and a liquefied gas container.

Background Art

[0002] Various gas containers for storing gas have been proposed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The gas container of Patent Document 1 includes a container body formed of a fiber-reinforced resin, and the inner surface of the container body is covered with a resin film provided with a gas barrier layer, achieving weight reduction compared to a metal container. In such a gas container structure, heat insulation is not considered, so it is not suitable for storing low-temperature liquefied gas. In addition, when storing a liquefied gas having strong oxidizing properties, such as liquefied oxygen, it is necessary to suppress ignition due to impact.

[0005] In consideration of the above facts, an object of the present invention is to provide a method for manufacturing a liquefied gas container and a liquefied gas container that are lightweight, have excellent heat insulation properties, and are suitable for storing a liquefied gas having strong oxidizing properties.

Means for Solving the Problems

[0006] A method for manufacturing a liquefied gas container according to claim 1 comprises: an inner container forming step of forming an inner container by attaching an intermediate member made of a fiber-reinforced thermoplastic resin to the outer surface of an inner container forming mandrel; an outer container component forming step of attaching the intermediate member to the outer surface of an outer container forming mandrel to form a plurality of outer container components for forming an outer container larger than the inner container; an outer container forming step of arranging the plurality of outer container components outside the inner container and connecting the outer container components to each other, and connecting the inner container and any of the outer container components with bosses to form the outer container outside the inner container; and a vacuum step of creating a vacuum in the space between the inner container and the outer container.

[0007] In the method for manufacturing a liquefied gas container according to claim 1, in the inner container forming step, an intermediate member having a fiber-reinforced thermoplastic resin is attached to the outer surface of an inner container forming mandrel to form the inner container. In the outer container component formation process, an intermediate member having a fiber-reinforced thermoplastic resin is attached to the outer surface of the outer container forming mandrel, thereby forming multiple outer container components that constitute an outer container larger than the inner container. In the outer container forming process, multiple outer container components are placed on the outside of the inner container and connected to each other, and the inner container is connected to one of the outer container components by a boss, thereby forming the outer container on the outside of the inner container. In the vacuum process, the space between the inner and outer containers is evacuated. This creates a vacuum-insulated space between the inner and outer containers.

[0008] The invention described in claim 2 is a method for manufacturing a liquefied gas container as described in claim 1, wherein in the inner container forming step, the tape-shaped intermediate member made of molten thermoplastic resin is wrapped around the outer surface of the inner container forming mandrel to form an inner container component in which the intermediate members are laminated, and in the outer container component forming step, the tape-shaped intermediate member made of molten thermoplastic resin is wrapped around the outer surface of the outer container forming mandrel to form an outer container component in which the intermediate members are laminated.

[0009] In the method for manufacturing a liquefied gas container according to claim 2, in the inner container forming step, a tape-shaped intermediate member made of molten thermoplastic resin is wrapped around the outer surface of the inner container forming mandrel to form an inner container component in which the intermediate members are laminated. In the outer container component formation process, a tape-shaped intermediate member made of molten thermoplastic resin is wrapped around the outer surface of the outer container forming mandrel to form an outer container component in which the intermediate members are laminated. By wrapping the intermediate member made of molten thermoplastic resin, the intermediate member wrapped later can be welded onto the intermediate member wrapped earlier, and the intermediate members can be joined together without using adhesive.

[0010] The method for manufacturing a liquefied gas container according to claim 3 is the method for manufacturing a liquefied gas container according to claim 1, wherein in the inner container forming step, the tape-shaped intermediate member made of molten thermoplastic resin is wrapped around the outer surface of a disassemblable mandrel consisting of a plurality of pieces, and after the thermoplastic resin has solidified, the disassemblable mandrel is disassembled and the pieces are taken out from inside the wrapped intermediate member to form the inner container.

[0011] In the method for manufacturing a liquefied gas container according to claim 3, in the inner container forming step, a tape-shaped intermediate member made of molten thermoplastic resin is wrapped around the outer surface of a disassemblable mandrel, and the intermediate members are laminated. After the thermoplastic resin has solidified, the disassemblable mandrel is disassembled, and pieces are removed from inside the wrapped intermediate members to obtain an inner container made of fiber-reinforced thermoplastic resin.

[0012] The invention described in claim 4 is a method for manufacturing a liquefied gas container according to claim 1 or claim 2, wherein the inner container forming step includes a gas barrier layer forming step in which a gas barrier layer is formed in the middle portion in the thickness direction of the intermediate members which are stacked in multiple layers.

[0013] The method for manufacturing a liquefied gas container according to claim 4 includes a gas barrier layer formation step in the inner container formation step, in which a gas barrier layer is formed in the middle portion in the thickness direction of the intermediate members that are laminated in multiple layers. This makes it possible to form a layer of fiber-reinforced thermoplastic resin with a gas barrier layer sandwiched inside. The gas barrier layer suppresses the permeation of vaporized gas from the liquefied gas and prevents gas from entering the vacuum insulation space and reducing the vacuum level of the vacuum insulation space. Furthermore, since the liquefied gas does not come into direct contact with the gas barrier layer, deterioration and damage to the gas barrier layer due to contact with the liquefied gas can be suppressed.

[0014] The liquefied gas container according to claim 5 comprises an outer container made of fiber-reinforced thermoplastic resin, an inner container disposed inside the outer container and made of a fiber-reinforced thermoplastic resin having gas barrier properties for storing liquefied gas, and a boss connecting the inner container and the outer container, with an opening formed in the inner container for the liquefied gas to enter and exit, wherein the space between the outer container and the inner container is a vacuum-insulated space.

[0015] In the liquefied gas container described in claim 5, liquefied gas can be stored in the inner container. Liquefied gas can be introduced into the inner container through the opening of a boss provided in the inner container, and the liquefied gas stored in the inner container can be removed through the opening.

[0016] A vacuum-insulated space is provided between the inner and outer containers, making it difficult for heat to transfer from the outer container to the inner container, resulting in a structure suitable for storing low-temperature liquefied gases. Furthermore, since both the inner and outer containers are made of fiber-reinforced thermoplastic resin, and no insulating material is provided between them, the liquefied gas container can be made lighter compared to a case where the inner and outer containers are made of metal and insulating material is provided between them.

[0017] The invention described in claim 6 is a liquefied gas container according to claim 5, wherein the inner container has a gas barrier layer sandwiched inside the fiber-reinforced thermoplastic resin.

[0018] In the liquefied gas container according to claim 6, the gas barrier layer sandwiched inside the fiber-reinforced thermoplastic resin suppresses the permeation of the gas vaporized from the liquefied gas, and can prevent the gas from entering the vacuum insulation space and reducing the degree of vacuum in the vacuum insulation space. Moreover, since the liquefied gas does not directly contact the gas barrier layer, deterioration and damage of the gas barrier layer due to contact with the liquefied gas can be suppressed.

[0019] The invention according to claim 7 is the liquefied gas container according to claim 5 or claim 6, wherein the boss has a suction port connected to the vacuum insulation space.

[0020] In the liquefied gas container according to claim 7, a vacuum pump is connected to the suction port via a pipe or the like, and the air intervening in the space between the inner container and the outer container is sucked, so that the space between the inner container and the outer container can be made into a vacuum insulation space.

Effect of the Invention

[0021] As described above, according to the method for manufacturing a liquefied gas container of the present invention, there is an excellent effect that a liquefied gas container suitable for storing a liquefied gas having strong oxidizing properties and being lightweight and excellent in heat insulation can be efficiently manufactured.

[0022] Moreover, the liquefied gas container of the present invention has an excellent effect that it is lightweight and excellent in heat insulation, and can be suitably used for storing a liquefied gas having strong oxidizing properties.

Brief Description of the Drawings

[0023] <0所 0100>(A) is a side view showing a partial cross-section of the liquefied gas container according to the first embodiment of the present invention, and (B) is a cross-sectional view showing a CFRP layer sandwiched with a barrier layer. [Figure 2] It is a perspective view showing a support ring. [Figure 3] (A) is a front view showing a boss, and (B) is a cross-sectional view showing the boss (a cross-sectional view taken along line B-B in FIG. 3(A)). [Figure 4] Figures (A) to (C) are explanatory diagrams showing the process of forming the mirror portion and the cylindrical portion of the inner container. [Figure 5] (A) and (B) are explanatory diagrams showing the process of joining the mirror portion and the cylindrical portion of the inner container. [Figure 6] (A) to (C) are explanatory diagrams showing the process of forming the mirror portion and the cylindrical portion of the outer container. [Figure 7] (A) to (C) are explanatory diagrams showing the process of forming an outer container on the outside of an inner container. [Figure 8] This is an explanatory diagram showing the process of joining the mirror portion and the cylindrical portion of the outer container. [Figure 9] This is a cross-sectional view along the axis showing a liquefied gas container according to a second embodiment of the present invention. [Figure 10] This is a cross-sectional view showing the inner container of a liquefied gas container according to the second embodiment. [Figure 11] This is a cross-sectional view showing the inner boss of a liquefied gas container according to the second embodiment. [Figure 12] (A) is a cross-sectional view showing the outer boss and lid of the liquefied gas container according to the second embodiment (a cross-sectional view taken along line 12A-12A in Figure 12(B)), and (B) is a front view showing the outer boss shown in Figure 12(A). [Figure 13] (A) and (B) are explanatory diagrams showing the process of forming the inner container. [Figure 14] (A) and (B) are explanatory diagrams showing the process of forming the inner container following Figure 13(B). [Figure 15] (A) to (D) are explanatory diagrams showing the process of forming the mirror portion and the cylindrical portion of the outer container. [Figure 16] This is a cross-sectional view showing the inner container with the outer boss and support ring attached. [Figure 17] This is a cross-sectional view showing how the mirror portion of the outer container is attached to one side of the inner container. [Figure 18] This is a cross-sectional view showing how the cylindrical portion that makes up the outer container is attached to the center of the inner container. [Figure 19]This is a cross-sectional view showing how the mirror portion of the outer container is attached to the other side of the inner container. [Figure 20] This is an explanatory diagram showing the main parts of the manufacturing process for a liquefied gas container according to another embodiment. [Figure 21] This is a side view showing a liquefied gas container according to another embodiment. [Modes for carrying out the invention]

[0024] [First Embodiment] A liquefied gas container 10 according to the first embodiment of the present invention and its manufacturing method will be described with reference to Figures 1 to 8. [Overall configuration of a liquefied gas container] As shown in Figure 1(A), the liquefied gas container 10 of this embodiment is composed of an outer container 12 made of fiber-reinforced thermoplastic resin, an inner container 14 made of fiber-reinforced thermoplastic resin disposed inside the outer container 12 and capable of storing liquefied gas, a pair of bosses 16 provided on the inner container 14 for bringing in and out liquefied gas, and a support ring 18 that supports the inner container 14 by floating it relative to the outer container 12, and a vacuum insulated space 20 is formed between the inner container 14 and the outer container 12.

[0025] (inner container) As shown in Figures 1(A) and 4(B) and (C), the inner container 14 of this embodiment has a cylindrical portion 14A, which is an example of an inner container component formed to a constant diameter, with hemispherical shell-shaped mirror portions 14B, also an example of an inner container component, integrally formed at both ends of the cylindrical portion 14A. A boss 16 is provided in the center of each mirror portion 14B.

[0026] In this embodiment, the inner container 14 is formed of CFRP (carbon fiber reinforced thermoplastic resin) as an example, and as shown in Figure 1(B), a gas barrier layer 24 is sandwiched in the middle of the thickness direction of the CFRP layer 22 of the inner container 14.

[0027] In this embodiment, the CFRP layer 22 can be formed, for example, using a tape-shaped thermoplastic prepreg. The method for forming the CFRP layer 22 in which the gas barrier layer 24 is embedded will be described later.

[0028] <Gas barrier layer> The gas barrier layer 24 of this embodiment mainly consists of a clay layer, and its basic composition consists of approximately 70% by mass or more of crystals of natural or synthetic swellable clay with a thickness of approximately 1 nm, a particle size of approximately 1 μm, and an aspect ratio of approximately 300, or of organic clay obtained by organic treatment of swellable clay, and approximately 30% by mass or less of natural or synthetic low-molecular-weight and high-molecular-weight organic additives with a molecular size of several nanometers or less. Here, organic treatment means silylation treatment or organic ion exchange treatment, and in this embodiment, the material obtained in this way is also included in the clay mineral.

[0029] This clay layer is fabricated by densely stacking layered crystals, oriented in the same direction. The resulting clay layer has a thickness of 3 to 100 μm, and its gas barrier performance is such that an oxygen permeability of 0.1 cc / m³ is achieved at a thickness of 30 μm. 2 • Less than 24hr·atm, hydrogen permeability 0.1cc / m³ 2 The current is less than 24hr·atm, the area can be increased to 100 × 40 cm or larger, and the DC electrical resistance perpendicular to the clay layer is 1 megaohm or more.

[0030] As the clay, natural or synthetic clay, preferably either natural smectite or synthetic smectite, or organic clay or a mixture thereof, is used and added to the solvent to prepare a dilute and homogeneous dispersion. As the clay, one or more of the group consisting of mica, vermiculite, montmorillonite, iron montmorillonite, bydelite, saponite, hectorite, stevensite, and nontronite can be used. The concentration of the clay dispersion is preferably 0.5 to 15% by mass, more preferably 1 to 10% by mass.

[0031] Next, a solid or liquid organic additive is added to the clay dispersion to prepare a homogeneous dispersion. The organic additive is not particularly limited as long as it improves the flexibility or mechanical strength of the adhesive clay film and mixes uniformly with the clay. For example, low molecular weight compounds such as ethylene glycol and glycerin, natural products such as dextrin, starch, gelatin, agar, wheat flour, and gluten, and thermosetting or thermoplastic resins used as the matrix resin described later can be used. In particular, alkyd resins, polyurethane resins, epoxy resins, fluororesins, acrylic resins, methacrylic resins, phenolic resins, polyamide resins, polyester resins, polyimide resins, polyvinyl resins, and silicone resins are preferred. The proportion of the organic additive added is 3 to 30% by mass, preferably 4 to 20% by mass, relative to the clay mineral. The order in which the clay dispersion and organic additive are mixed is also possible; the clay can be added to the solvent first, followed by the organic additive, or vice versa. Alternatively, the clay dispersion and organic additive solution can be prepared separately and then mixed.

[0032] As a method for producing the clay layer, for example, a liquid dispersion is slowly evaporated over the substrate (CFRP layer 22 in this embodiment) to form a film. For drying, for example, in a forced-air oven, preferably at a temperature of 30 to 50°C, the clay layer is obtained by drying for about 10 minutes to half a day, preferably 10 minutes to 5 hours.

[0033] (outer container) As shown in Figure 1(A), the outer container 12 is positioned outside the inner container 14 with a gap between them. Similar to the inner container 14, the outer container 12 has a cylindrical portion 12A, which is an example of an outer container component formed to a constant diameter, with mirror portions 12B, also an outer container component, integrally formed at both ends. For example, the outer container 12 is made of CFRP, similar to the inner container 14, but the CFRP layer 26 of the outer container 12 does not have a gas barrier layer 24.

[0034] (Support ring) In the liquefied gas container 10 of this embodiment, a support ring 18 is provided between the outer container 12 and the inner container 14 to suspend and support the inner container 14 within the outer container 12.

[0035] As shown in Figure 2, the support ring 18 is formed by connecting a plurality of arc-shaped ring pieces 18A in a ring shape. Each ring piece 18A has a hole 18B that penetrates through it along the axial direction of the ring piece 18A. The support ring 18 is made of a material with a lower thermal conductivity than metal, such as synthetic resin.

[0036] (boss) As shown in Figure 1(A), the bosses 16 are provided on both longitudinal ends of the inner container 14. Note that the boss 16 on the right side of the drawing and the boss 16 on the left side of the drawing have the same configuration.

[0037] As shown in Figures 3(A) and 3(B), the boss 16 of this embodiment is composed of an inner boss member 30 and an outer boss member 32. The inner boss member 30 and the outer boss member 32 are made of a metallic material, for example, aluminum or an aluminum alloy, but they can also be made of a material other than a metallic material, for example, a synthetic resin (such as a carbon fiber reinforced thermoplastic resin).

[0038] The inner boss member 30 has a shaft portion 30A with a constant outer diameter, and an outer flange 30B is integrally formed at the inner container side end of the shaft portion 30A, which is curved to conform to the inner surface shape of the mirror portion 14B of the inner container 14. As shown in Figure 4(B), the outer flange 30B is embedded in the CFRP layer 22.

[0039] As shown in Figures 3(A) and (B), a flow channel 34 is formed in the axial center of the inner boss member 30, penetrating the inner boss member 30 in the axial direction. Four screw holes 36 are formed on the end face of the shaft portion 30A of the inner boss member 30, opposite to the outer flange 30B.

[0040] The outer boss member 32 has a shaft portion 32A with the same diameter as the shaft portion 30A of the inner boss member 30, and an outer flange 32B is integrally formed in the axial middle portion of the shaft portion 32A, which is curved to conform to the inner surface shape of the mirror portion 12B of the outer container 12. As shown in Figure 1(A), a portion of the shaft portion 32A protrudes to the outside of the outer container 12, and the outer flange 32B is embedded in the CFRP layer 26 of the outer container 12.

[0041] As shown in Figures 3(A) and 3(B), a channel 38 is formed in the axial center of the outer boss member 32, which penetrates the outer boss member 32 in the axial direction and connects to the channel 34 of the inner boss member 30. A female thread 38A is formed at the end of the flow path 38. A fitting 41, which is attached to a pipe 39 for supplying and discharging fluid to and from the inner container 14, is connected to this female thread 38A.

[0042] The shaft portion 32A of the outer boss member 32 has a bolt insertion hole 40 that penetrates axially, and an air intake port 42 used to draw in and exhaust air from the space between the outer container 12 and the inner container 14. The air intake port 42 is an example of an intake port of the present invention.

[0043] The bolt insertion hole 40 is provided in a position opposite to the screw hole 36 of the inner boss member 30. By screwing the threaded portion 44A of the bolt 44 inserted through the bolt insertion hole 40 into the screw hole 36 of the inner boss member 30, the outer boss member 32 can be fixed to the inner boss member 30, thereby integrating the outer boss member 32 and the inner boss member 30.

[0044] The air intake port 42 is L-shaped, with one end opening to the end face of the shaft portion 32A of the outer boss member 32, and the other end opening to the outer circumferential surface of the shaft portion 32A on the inner boss member 30 side of the outer flange 32B. A female screw 42A is formed on the end face side of the shaft portion 32A of the outer boss member 32 in the air intake port 42. A fitting 46 is attached to this female screw 42A. The fitting 46 is detachably connected to an air suction pipe 48 that is connected to a vacuum pump (not shown), and has a check valve (not shown) built inside. The check valve is open when air in the space between the inner container 14 and the outer container 12 is drawn out of the container, and prevents the flow of air from entering the space from outside the container. Note that a shut-off valve may be provided in place of the check valve in the fitting 46.

[0045] [Method for manufacturing liquefied gas containers] The manufacturing process for the thermoplastic prepreg 52 for forming the CFRP layer 22 of the inner container 14 and the CFRP layer 26 of the outer container 12, and the liquefied gas container 10 of this embodiment will be described below. (Thermoplastic prepreg) The thermoplastic prepreg 52 used in this embodiment is composed of carbon fibers and a thermoplastic resin, as described below. <Carbon fiber> The carbon fiber used in this embodiment has a tensile modulus of 700 GPa or more, preferably 750 GPa or more. When the tensile modulus is within this range, the probability of ignition by impact in the presence of liquid oxygen is sufficiently low. On the other hand, there is no particular upper limit to the tensile modulus, but from the viewpoint of formability, it is preferably 1200 GPa or less, more preferably 1000 GPa or less, and even more preferably 900 GPa or less. Here, the tensile modulus of the carbon fiber refers to the value measured by the measurement method of JIS R 7606 (ISO 11566:1996).

[0046] Such carbon fibers are preferably those that ignite 2 times or less, more preferably 1 time or less, and most preferably 0 times, when subjected to impact testing (liquid oxygen compatibility testing) using an ABMA type impact testing apparatus compliant with the ASTM (American Society for Testing and Materials) test method standard "D2512-95" for 20 tests.

[0047] Any type of carbon fiber can be used, such as polyacrylonitrile (PAN), pitch, or rayon, but pitch-based carbon fiber is preferred because it tends to have a high tensile modulus. The crystalline structure of carbon differs depending on the starting material, and pitch-based carbon fibers are characterized by producing graphite fibers in which graphite crystals are more highly oriented in the fiber axis direction than PAN-based carbon fibers. For example, when mesophase pitch is used as the starting material, ultra-high modulus carbon fibers with a modulus exceeding 900 GPa can be obtained.

[0048] <Thermoplastic resin> The thermoplastic resin used in this embodiment is a flame-retardant resin that has a low probability of ignition by impact in the presence of liquid oxygen. Specifically, in an impact test using an ABMA type impact test apparatus compliant with the ASTM (American Society for Testing and Materials) test method standard "D2512-95", the resin ignites 2 times or less when the test is performed 20 times, preferably 1 time or less, and particularly preferably 0 times.

[0049] Furthermore, in this embodiment, a thermoplastic resin with lower ignition properties than a thermosetting resin is used as the flame-retardant thermoplastic resin. Examples of flame-retardant thermoplastic resins include polyacetal (POM), polycarbonate (PC), polyetherimide (PEI), polyethersulfone (PES), polyetheretherketone (PEEK), and fluororesins. Specific examples of fluororesins include polytetrafluoroethylene (PTFE), ethylenetetrafluoroethylene (ETFE), and perfluoroalkyl vinyl ether copolymer (PFA). Among these resins, polycarbonate, polyetheretherketone, polytetrafluoroethylene, ethylenetetrafluoroethylene, and perfluoroalkyl vinyl ether copolymer are preferred, and polycarbonate and polyetheretherketone are preferred from the viewpoint of suitability for compounding with carbon fibers.

[0050] Polycarbonate is particularly preferred as the flame-retardant thermoplastic resin. Specifically, the thermoplastic prepreg 52 used in this embodiment is particularly preferably composed of carbon fibers having a tensile modulus of 700 GPa or more and polycarbonate.

[0051] Polycarbonate is easily combined with carbon fiber to form intermediate materials such as prepregs and semipregs, and the CFRP layer 22 can also be easily formed. In other words, it is easy to form curved surfaces and complex shapes.

[0052] Furthermore, polycarbonate exhibits high fracture strain at extremely low temperatures of around -200°C, and CFRP, which is a composite of polycarbonate and polycarbonate, is less prone to matrix cracking caused by extremely low temperatures.

[0053] Furthermore, polycarbonate exhibits good adhesion to aluminum alloys used in boss 16, for example, at extremely low temperatures of around -200°C. Therefore, CFRP composites incorporating polycarbonate are suitable as materials for containers that store low-temperature liquids, such as liquid oxygen tanks.

[0054] (Formation of the inner container) Next, we will explain the manufacturing process of the inner container 14. Figure 4(A) shows the inner container forming mandrel 50 and inner boss member 30 for forming the CFRP layer 22 of the inner container 14. The mandrel 50 for forming the inner container has a constant diameter section 50A formed in the axial center and dome sections 50B formed in a substantially hemispherical shape at both ends. The mandrel 50 for forming the inner container in this embodiment is made of a metal material or the like. In forming the CFRP layer 22, the inner boss member 30 is temporarily fixed to the dome portion 50B of the inner container forming mandrel 50 using an adhesive with weak adhesive strength.

[0055] Next, as shown in Figure 4(B), a thermoplastic prepreg 52, which is an example of an intermediate member formed in the shape of a tape, is wound using an adhesive device 54 to cover the dome portion 50B and the outer flange 30B of the inner boss member 30, thereby forming a CFRP layer 22 of a predetermined thickness.

[0056] The adhesive application device 54 is equipped with a robot 56, and the tip of the robot arm 56A is fitted with a reel 58 on which thermoplastic prepreg 52 is wound, a heater 60 that heats the thermoplastic prepreg 52 drawn from the reel 58 to melt the thermoplastic resin, and a pressing roller 62 that presses the thermoplastic prepreg 52 heated by the heater 60.

[0057] In this embodiment, in order to form the CFRP layer 22 in which the gas barrier layer 24 is embedded, first, thermoplastic prepreg 52 is wound around to cover the outer circumferential surface of the dome portion 50B of the inner container forming mandrel 50 and the entire outer flange 30B of the inner boss member 30 with thermoplastic prepreg 52. The thermoplastic prepreg 52 is laminated to a predetermined thickness. Then, the gas barrier layer 24 is formed on the layer of thermoplastic prepreg 52 of the predetermined thickness, and after that, the mirror portion 14B is formed by further winding of thermoplastic prepreg 52 to cover the outer surface of the gas barrier layer 24.

[0058] Since the piping connected to the liquefied gas container 10 is made of metal, a metal boss 16 is attached to the joint between the liquefied gas container 10 and the piping. The metal material constituting the boss 16 has a higher coefficient of thermal expansion than the CFRP layer 22, and internal pressure is applied to the inner container 14 of the liquefied gas container 10, so interfacial delamination is likely to occur between the boss 16 and the CFRP layer 22 at extremely low temperatures. However, polycarbonate can be suitably used for bonding (welding) the boss 16 and the CFRP layer 22, thereby effectively preventing interfacial delamination. Furthermore, by using flame-retardant polycarbonate instead of adhesives that pose a risk of ignition, the risk of oxygen ignition can be avoided.

[0059] Furthermore, in order to increase the adhesive strength between the CFRP layer 22 and the boss 16, it is preferable to perform known surface roughening treatments such as laser processing, sandblasting, or etching on the surface of the boss 16 to create minute irregularities on the surface and roughen the surface.

[0060] After winding and laminating the thermoplastic prepreg 52 to a predetermined thickness, the aforementioned clay-containing dispersion is applied to the surface of the thermoplastic prepreg 52 layer and dried to form a gas barrier layer 24 over the entire surface of the thermoplastic prepreg 52 layer.

[0061] After forming a gas barrier layer 24 over the entire surface of the thermoplastic prepreg 52 layer in this manner, the thermoplastic prepreg 52 is further wound around to cover the gas barrier layer 24, forming a mirror portion 14B of a predetermined thickness. After the thermoplastic resin of the thermoplastic prepreg 52 has cooled and solidified, the mirror portion 14B is removed from the inner container forming mandrel 50.

[0062] Next, as shown in Figure 4(C), a cylindrical portion 14A is formed on the outer circumference of the constant diameter portion 50A of the inner container forming mandrel 50 through the same process as for the mirror portion 14B.

[0063] Next, as shown in Figure 5(A), the end of the mirror portion 14B removed from the inner container forming mandrel 50 and the end of the cylindrical portion 14A removed from the inner container forming mandrel 50 are butted together, and the shaft 64 is inserted through the flow path 34 of the inner boss member 30 of one mirror portion 14B and the flow path 34 of the inner boss member 30 of the other mirror portion 14B. Then, a support roller 66 is brought into contact with the lower part of the cylindrical portion 14A to prevent it from shifting, supporting the pair of mirror portions 14B and cylindrical portion 14A. Then, using an adhesive device 54, thermoplastic prepreg 52, which is molten thermoplastic resin, is wound around the outer circumference of the butt joint portion 78 where the ends of the mirror portion 14B and the ends of the cylindrical portion 14A are butted together, and as shown in Figure 5(B), the mirror portion 14B and the cylindrical portion 14A are joined together with the thermoplastic prepreg 52. This completes the inner container 14 with the inner boss member 30 integrated.

[0064] (Formation of the outer container) Next, the manufacturing process for the outer container 12 will be explained. Figure 6(A) shows the outer container forming mandrel 70 and outer boss member 32 for forming the CFRP layer 26 of the outer container 12. The outer container forming mandrel 70 has a constant diameter portion 70A formed in the axial center and dome portions 70B formed in a substantially hemispherical shape at both ends. A hole 72 for inserting the shaft portion 32A of the outer boss member 32 is formed in the axial center of the dome portion 70B. The outer container forming mandrel 70 in this embodiment is made of a metal material or the like, similar to the inner container forming mandrel 50.

[0065] In the outer container formation process, first, as shown in Figure 6(A), the shaft portion 32A of the outer boss member 32 is inserted into the hole 72 of the outer container forming mandrel 70 and supported by the shaft 64. Next, as shown in Figure 6(B), the thermoplastic prepreg 52, which is formed in a tape shape, is wound using an adhesive device 54 to cover the outer circumferential surface of the dome portion 70B and the outer flange 32B of the outer boss member 32, thereby forming the mirror portion 12B of the outer container 12.

[0066] Next, as shown in Figure 6(C), the mandrel 70 for forming the outer container is supported by the shaft 82, and the cylindrical portion 12A is formed on the outer circumference of the constant diameter portion 70A through the same process as for the mirror portion 12B.

[0067] (Joining the inner and outer containers) Next, the joining process between the inner container 14 and the outer container 12 will be explained. When joining the inner container 14 and the outer container 12, first the inner container 14 is supported by the shaft 64, and the support ring 18 is fixed to the outer circumference of the abutting portion 78 between the mirror portion 14B and the cylindrical portion 14A with adhesive or the like (see Figure 7(A)).

[0068] After fixing the support ring 18, as shown in Figures 7(A) to (C), the pair of mirror portions 12B and cylindrical portions 12A that constitute the outer container 12 are positioned on the outside of the inner container 14, the outer boss member 32 is fixed to the inner boss member 30 with bolts 44, and the ends of the mirror portion 12B and the ends of the cylindrical portion 12A are brought into contact. In this embodiment, the lengths of the mirror portion 14B and cylindrical portion 14A of the inner container 14, and the mirror portion 12B and cylindrical portion 12A of the outer container 12 are determined so that the joint between the mirror portion 12B and cylindrical portion 12A of the outer container 12 is located on the outer circumferential surface of the support ring 18.

[0069] Next, as shown in Figure 8, the assembly in which the mirror portion 12B and the cylindrical portion 12A are temporarily assembled is rotatably supported on the outside of the inner container 14 by a shaft 64. Using an adhesive device 54, a thermoplastic prepreg 52 made of molten thermoplastic resin is wound around the outer circumference of the butt joint portion 80 where the ends of the mirror portion 12B and the ends of the cylindrical portion 12A of the outer container 12 meet, thereby joining the mirror portion 12B and the cylindrical portion 12A of the outer container 12. This integrates the inner container 14 and the outer container 12.

[0070] Finally, the female screw 42A of the air intake port 42 of the boss 16 is connected to the fitting 46 and the air intake piping 48, and the air in the space between the inner container 14 and the outer container 12 is sucked out with a vacuum pump. By removing the air from the space between the inner container 14 and the outer container 12 and creating a vacuum inside the space, the liquefied gas container 10 is completed, with the space becoming a vacuum-insulated space 20. In this embodiment, 1 × 10 -2 Vacuum is defined as anything below Pa.

[0071] (Effect, Action) In the liquefied gas container 10 of this embodiment, for example, liquefied gas such as liquid oxygen can be introduced into the inner container 14 through the joint 41 of one boss 16, and the liquefied gas inside the container can be discharged through the joint 41 of the other boss 16.

[0072] In the liquefied gas container 10 of this embodiment, a vacuum insulation space 20 is provided between the inner container 14 and the outer container 12. This makes it difficult for heat to be transferred from the outer container 12 to the inner container 14, resulting in a structure suitable for storing low-temperature liquefied gas.

[0073] Both the inner container 14 and the outer container 12 are made of CFRP, which is a carbon fiber reinforced thermoplastic resin, and there is no insulating material between the inner container 14 and the outer container 12. Therefore, the liquefied gas container 10 can be made lighter compared to when the inner container 14 and the outer container 12 are made of metal and insulating material is provided between them.

[0074] In the liquefied gas container 10 of this embodiment, the gas barrier layer 24 sandwiched inside the CFRP layer 22 that constitutes the inner container 14 suppresses gas permeation, thereby preventing gas from entering the vacuum insulation space 20 and reducing the vacuum level of the vacuum insulation space 20. Furthermore, since the liquefied gas stored in the inner container 14 does not come into direct contact with the gas barrier layer 24, deterioration and damage to the gas barrier layer 24 due to contact with the liquefied gas can be suppressed.

[0075] In this embodiment, the gas barrier layer 24 has a structure in which clay minerals having a plate-like crystalline structure are oriented in one direction and densely laminated. Therefore, it is possible to obtain gas barrier properties equivalent to those obtained when formed from metal, while also reducing weight.

[0076] By using polycarbonate (PC), a flame-retardant thermoplastic resin, and carbon fibers with a high tensile modulus in the CFRP layer 22 that constitutes the inner container 14, the probability of ignition by impact in the presence of highly oxidizing liquid oxygen can be reduced to the same extent as that of metal materials.

[0077] A check valve may be installed in the air intake port 42. If a check valve is installed, when the piping connected to the vacuum pump is disconnected from the air intake port 42, outside air can be prevented from flowing into the vacuum-insulated space 20, eliminating the need to seal the air intake port 42 with a lid or the like. Furthermore, if the vacuum level of the vacuum-insulated space 20 decreases, the gas interposed in the vacuum thermal space can be drawn in again to increase the vacuum level of the vacuum-insulated space 20.

[0078] [Second Embodiment] A liquefied gas container 110 according to a second embodiment of the present invention and its manufacturing method will be described with reference to Figures 9 to 18. Components identical to those in the first embodiment are denoted by the same reference numerals, and their descriptions are omitted.

[0079] As shown in Figure 9, the liquefied gas container 110 of this embodiment is composed of an outer container 112 made of fiber-reinforced thermoplastic resin, an inner container 114 made of fiber-reinforced thermoplastic resin disposed inside the outer container 112 and capable of storing liquefied gas, a pair of inner bosses 116 provided on the inner container 114, outer bosses 119 connecting the inner container 114 and the outer container 112 at both axial ends, a support ring 118 that supports the inner container 114 in a floating position relative to the outer container 112, a lid 138 that closes the opening of the outer bosses 119, and so on, and a vacuum insulated space 120 is formed between the inner container 114 and the outer container 112.

[0080] (inner container) As shown in Figures 9 and 10, the inner container 114 of this embodiment is a cylindrical portion 114A with a constant diameter in the axial middle section, and mirror portions 114B are formed on both axial sides of the cylindrical portion 114A.

[0081] In this embodiment, the inner container 114 is formed of CFRP (carbon fiber reinforced thermoplastic resin) similar to that in the first embodiment, and a gas barrier layer 24 (not shown) similar to that in the first embodiment is sandwiched between the CFRP layer 122 of the inner container 114.

[0082] An inner boss 116 is joined to the central inner circumferential surface side of the mirror portion 114B of the inner container 14. As shown in Figure 11, the inner boss 116 of this embodiment is formed in an annular shape, with a constant thickness on the inner circumference and a tapered shape on the outer circumference where the thickness gradually decreases towards the radially outward direction. The portion of the inner boss 116 formed in a constant thickness is called the constant thickness portion 116A, and the portion formed in a tapered shape is called the tapered portion 116B.

[0083] The inner boss 116 is formed from a metallic material, such as aluminum or an aluminum alloy, but it can also be formed from a material other than a metallic material, such as a synthetic resin (carbon fiber reinforced thermoplastic resin, etc.).

[0084] (outer container) As shown in Figure 9, the outer container 112 is positioned outside the inner container 114 with a gap between them. The outer container 112 is formed by joining a cylindrical portion 112A, which is an example of an outer container component formed to a constant diameter, and a mirror portion 112B, which is also an outer container component. For example, the outer container 112 is made of CFRP similar to the inner container 114, but the CFRP layer 126 of the outer container 112 does not have a gas barrier layer 24.

[0085] (Support ring) Similar to the liquefied gas container 10 of the first embodiment, the liquefied gas container 110 of this embodiment is also provided with a support ring 118 between the outer container 112 and the inner container 114, which suspends and supports the inner container 114 within the outer container 112.

[0086] (Outer boss) As shown in Figures 12(A) and (B), the outer boss 119 is formed in an annular shape. The outer boss 119 is formed with a constant thickness on the inner circumference and has a tapered shape on the outer circumference, with the thickness gradually decreasing towards the radially outward direction. The portion of the outer boss 119 formed with a constant thickness is called the constant thickness portion 119A, the portion formed in a tapered shape is called the tapered portion 119B, and the central opening is called the central opening 119C.

[0087] Multiple arc-shaped openings 130 are formed along the circumferential direction in the portion of constant thickness 119A. Although the openings 130 in this embodiment are arc-shaped, they may be circular or of other shapes.

[0088] Furthermore, the outer boss 119 is the outer surface of the constant thickness portion 119A (right side of the drawing in Figure 12(A)), with a first annular groove 132 formed on the inner circumference side of the opening 130, a second annular groove 134 formed on the outer circumference side of the opening 130, and a screw hole 136 formed between the openings 130. The first annular groove 132 is fitted with the first O-ring 132A, and the second annular groove 134 is fitted with the second O-ring 134A.

[0089] (lid) As shown in Figures 9 and 12(A), a disc-shaped cover 138 is positioned on the outside of the outer boss 119. The cover 138 is made of a metal material, for example, aluminum or an aluminum alloy, but it can also be made of a synthetic resin (such as carbon fiber reinforced thermoplastic resin).

[0090] The lid 138 has a through hole 140 formed in a position opposite to the screw hole 136 of the outer boss 119. The lid 138 is fixed in close contact with a certain thickness portion 119A of the outer boss 119 by screwing a bolt 142 through the through hole 140 into the screw hole 136 and tightening it. As a result, the central opening 119C and the opening 130 of the outer boss 119 are closed by the lid 138. In addition, the first O-ring 132A and the second O-ring 134A are in close contact with the side surface of the lid 138, thereby sealing the gap between the outer boss 119 and the lid 138.

[0091] A flow channel 144 is formed in the center of the lid 138, and a joint 146 communicating with the flow channel 144 is provided on the outer surface of the lid 138. A pipe 39 for introducing and discharging fluid is connected to this joint 146, similar to the first embodiment (see Figure 3).

[0092] An air intake port 150 is formed on the lid 138 at a position opposite to one of the openings 130 of the outer boss 119. The air intake port 150 is an example of an intake port of the present invention. A joint 152 communicating with the air intake port 150 is provided on the outer surface of the lid 138. Similar to the joint 46 of the first embodiment, a check valve (not shown) is built into the joint 152. Alternatively, an on / off valve may be provided in place of the check valve in the joint 152.

[0093] Similar to the first embodiment, the fitting 152 is detachably connected to an air suction pipe 48 that is connected to a vacuum pump.

[0094] (Method of manufacturing liquefied gas containers) Next, the manufacturing process of the liquefied gas container 110 of this embodiment will be described with reference to the drawings.

[0095] (Formation of the inner container) Figure 13(A) shows a cross-sectional view of the disassemblable mandrel 154 used to form the inner container 14. The disassemblable mandrel 154 is formed in a cylindrical shape by multiple pieces 154A, 154B made of metal or the like.

[0096] First, a release film 156 is attached to the outer surface of the disassemblable mandrel 154, excluding a portion of both axial ends.

[0097] Next, as shown in Figure 13(B), the inner bosses 116 are temporarily fixed to both axial ends of the disassembled mandrel 154.

[0098] Next, as shown in Figure 14(A), the thermoplastic prepreg 52, which is formed in a tape shape, is wound using an application device 54 to cover the outer surface of the disassemblable mandrel 154 and the inner boss 116, thereby forming a CFRP layer 122 of a predetermined thickness. A gas barrier layer 24 (not shown in Figure 14(A)) is formed on the CFRP layer 122, similar to the CFRP layer 22 in the first embodiment.

[0099] After the thermoplastic resin of the thermoplastic prepreg 52 has cooled and solidified, the disassemblable mandrel 154 is disassembled as shown in Figure 14(B), all pieces 154A and 154B are removed to the outside through the opening of the inner boss 116, and the release film 156 is peeled off.

[0100] Next, as shown in Figure 10, a radiant heat suppression film 158 that reflects radiant heat is attached to a predetermined location on the outer surface of the inner container 114. As an example, the radiant heat suppression film 158 can be Super Insulation (product name) from Kaneka Corporation. In this embodiment, since the support ring 18 is directly attached to the CFRP layer 122 of the inner container 114, the radiant heat suppression film 158 is not attached to the area 160 on the outer surface of the inner container 114 where the support ring 118 is to be attached.

[0101] (Formation of the outer container) Figure 15(A) shows the outer container forming mandrel 162 for forming the cylindrical portion 112A and the mirror portion 112B of the outer container 112. The mandrel 162 for forming the outer container is formed in a roughly cylindrical shape and, for example, is made of a metal material or the like, similar to the disassemblable mandrel 154. The mandrel 162 for forming the outer container has a constant diameter section 162A in its axial center, and dome sections 162B at both ends. The mandrel 162 for forming the outer container is rotatably supported by an axis (not shown).

[0102] In the process of forming the outer container 112, first, as shown in Figure 15(B), the thermoplastic prepreg 52 is wound using an adhesive device 54 to cover the outer circumferential surface of one of the dome portions 162B, thereby forming one of the mirror portions 112B of the outer container 112, and then the mirror portion 112B is removed from the dome portion 162B.

[0103] Next, as shown in Figure 15(C), the cylindrical portion 112A of the outer container 112 is formed on the outer circumference of the constant diameter portion 162A of the outer container forming mandrel 162, and then the cylindrical portion 112A is removed from the constant diameter portion 162A.

[0104] Next, as shown in Figure 15(D), the thermoplastic prepreg 52 is wound around the outer surface of the other dome portion 162B of the outer container forming mandrel 162 to form the other mirror portion 112B of the outer container 112, and then the other mirror portion 112B is removed from the dome portion 162B.

[0105] (Joining the inner and outer containers) When joining the inner container 114 and the outer container 112, first, as shown in Figure 16, a support ring 118 is joined to the outer surface of the inner container 114 by adhesive or other means, and outer bosses 119 are joined to both axial ends of the inner container 114 by adhesive or other means.

[0106] Next, as shown in Figure 17, the mirror portion 112B is positioned so as to straddle one of the outer bosses 119 and the support ring 118. The mirror portion 112B is then pressed against the outer boss 119 with a heated roller 164, melting the resin of the CFRP layer 126 and welding the mirror portion 112B to the outer boss 119. Similarly, the mirror portion 112B is pressed against the support ring 118 with a heated roller 164, melting the resin of the CFRP layer 126 and welding the mirror portion 112B to the support ring 118.

[0107] Next, as shown in Figure 18, the cylindrical portion 112A is positioned so as to straddle one support ring 118 and the other support ring 118. Then, a heated roller 164 (not shown in Figure 18) is used to press one mirror portion 112B and the cylindrical portion 112A against one support ring 118, melting the resin of the CFRP layer 126 of one mirror portion 112B and the resin of the CFRP layer 126 of the cylindrical portion 112A, thereby welding the end of one mirror portion 112B and the end of the cylindrical portion 112A to one support ring 118.

[0108] Subsequently, the thermoplastic prepreg 52 is wrapped around the outer circumference of the joint between the mirror portion 112B and the cylindrical portion 112A using the adhesive device 54 and welded to it.

[0109] Next, as shown in Figure 19, the mirror portion 112B is positioned to straddle the other support ring 118 and the other outer boss 119, and the end of the cylindrical portion 112A and the end of the mirror portion 112B are welded to the other support ring 118 using a heated roller 164. Next, a thermoplastic prepreg 52 is wound and welded around the outer circumference of the joint between the mirror portion 112B and the cylindrical portion 112A using an adhesive device 54 (not shown in Figure 19). Subsequently, the cylindrical portion 112A is welded to the outer boss 119 using the heated roller 164.

[0110] Next, as shown in Figure 9, the cover 138 is attached to the outer boss 119 using bolts 142, and the joints 146 and 152 are attached to the cover 138.

[0111] Finally, an air suction pipe 48 is connected to the joint 152 of the lid 138, and the air in the space between the inner container 114 and the outer container 112 is sucked out with a vacuum pump to create a vacuum in the space, thereby completing the liquefied gas container 110, which has a vacuum-insulated space 120.

[0112] Furthermore, the lid 138 of the liquefied gas container 110 may, if necessary, be covered with a radiant heat suppression film 158 or with an insulating material 166 made of inorganic fibers such as glass wool or rock wool, or foamed resin such as polystyrene foam, urethane foam, phenolic foam, or expanded polystyrene. As an example, the lid 138 may have a double-layer structure, with a vacuum insulation layer provided on the lid 138.

[0113] (Effect, Action) In the liquefied gas container 110 of this embodiment, a vacuum insulation space 20 is provided between the inner container 114 and the outer container 112, and a radiant heat suppression film 158 that reflects radiant heat is attached to the outer surface of the inner container 114. Therefore, the liquefied gas container 110 of this embodiment has higher heat insulation performance compared to the case in which the radiant heat suppression film 158 is not attached. In this embodiment, the radiant heat suppression film 158 is attached to the inner container 114, but it may also be attached to the outer container 112. Note that the radiant heat suppression film 158 may be attached or omitted depending on the application.

[0114] In this embodiment, the liquefied gas container 110 is used, for example, with its axial direction oriented vertically (i.e., rotated 90° from the state shown in Figure 9). In this case, the fluid inside the inner container 114 can be discharged from the lower pipe 39.

[0115] Furthermore, in order to suppress fluctuations in the liquid surface due to vibration, i.e., sloshing, in the liquefied gas container 110, it is preferable to provide a ring-shaped baffle 168 on the inner circumferential surface of the inner container 114, as shown by the dashed line in Figure 9. Since the outer diameter of the baffle 168 is larger than the inner diameter of the inner boss 116, the baffle 168 can be made to be divided into two parts (or three or more parts), and the divided baffle 168 can be inserted into the inside of the inner container 114 through the opening of the inner boss 116 and assembled into a ring shape inside the container. The baffle 168 can be formed from a metal material, such as aluminum or an aluminum alloy, or from a synthetic resin other than a metal material (such as carbon fiber reinforced thermoplastic resin).

[0116] If the liquefied gas container 110 of this embodiment is relatively large enough for a worker to enter, the divided baffles 168 can be assembled into a ring shape inside the inner container 114 by the worker.

[0117] [Other embodiments] Although embodiments of the present invention have been described above, the present invention is not limited to those described above, and it is of course possible to implement it in various modified forms without departing from the spirit of the invention.

[0118] In the first embodiment described above, when forming the outer container 12, two mirror portions 12B and one cylindrical portion 12A were formed and these three members were joined together. However, as an example, as shown in Figure 20, two members may be formed: one in which the mirror portion 12B and the cylindrical portion 12A are integrated, and the other being the mirror portion 12B, and these two members may be joined together. Although not shown, the outer container 112 of the second embodiment can be formed in the same manner.

[0119] Furthermore, in the first embodiment, a long liquefied gas container 10 can be formed by connecting a plurality of cylindrical sections 12A to form an outer container 12 and connecting a plurality of cylindrical sections 14A to form an inner container 14. Although not shown in the figures, in the liquefied gas container 110 of the second embodiment, a long liquefied gas container 110 can be formed by forming a long inner container 114 and connecting a plurality of cylindrical sections 112A to form an outer container 112.

[0120] Although the liquefied gas container 10 in the first embodiment described above was formed in an elongated shape, it may also be formed in a spherical shape as shown in Figure 21, and the shape of the liquefied gas container 10 can be changed as appropriate. The liquefied gas container 10 shown in Figure 21 can be formed, for example, by joining mirror portions facing each other.

[0121] In the manufacturing method of the liquefied gas container 10 of the second embodiment described above, the pieces 154A and 154B that were disassembled from the inner container 14 were removed to the outside before joining the inner container 14 and the outer container 12. However, they may also be removed after joining the inner container 14 and the outer container 12.

[0122] The liquefied gas containers 10 and 110 of the above embodiment can store not only liquefied oxygen, but also various other liquefied gases such as liquefied hydrogen, liquefied helium, liquefied nitrogen, and LNG (liquefied natural gas).

[0123] In the above embodiment, CFRP (carbon fiber reinforced plastic) was used as the fiber-reinforced thermoplastic resin, but other known materials such as GFRP (glass fiber reinforced plastic) and AFRP (aramid fiber reinforced plastic) may be used as needed. However, thermoplastic resin should be used in parts that come into contact with liquid oxygen.

[0124] In the first embodiment described above, the boss 16 was made of aluminum or an aluminum alloy, but the boss 16 may be made of other metallic materials, or non-metallic materials such as ceramics or synthetic resins that have lower thermal conductivity than metallic materials, as long as they are suitable for storing liquefied gas.

[0125] In the liquefied gas container 10 of the first embodiment described above, bosses 16 were provided on both sides in the axial direction. However, it is sufficient to have one boss 16 at one end, and the other end may, for example, be a plug with the same external shape as the boss 16, but without a flow path 34 and an air intake port 42. In other words, the plug at the other end does not have the function of allowing liquefied gas to enter or exit, and only needs to be supported by the shaft 64 used during manufacturing. In the first embodiment described above, a shaft 64 was used when manufacturing the liquefied gas container 10, but the shaft 64 does not need to be used as long as the liquefied gas container 10 can be manufactured.

[0126] In the liquefied gas container 110 of the second embodiment described above, inner bosses 116 and outer bosses 119 were provided on both sides in the axial direction. However, as in the first embodiment, the inner bosses 116 and outer bosses 119 only need to be provided on one end in the axial direction. [Explanation of Symbols]

[0127] 10. Liquefied gas containers 12 Outer container 12A Cylindrical part (outer container component) 12B Mirror part (outer container component) 14 Inner container 14A Cylindrical part (inner container component) 14B Mirror part (inner container component) 16 Bosses 20 Vacuum-insulated space 22 CFRP layers 24 Gas barrier layer 26 CFRP layers 42 Air intake port (intake port) 50 Mandrel for forming inner container 52 Thermoplastic prepreg (intermediate material) 70 Mandrel for forming outer container 110 Liquefied gas containers 112 Outer container 112A Cylindrical part (outer container component) 112B Mirror part (outer container component) 114 Inner container 119 Outer Boss 122 CFRP layer 126 CFRP layers 150 Air intake port (intake port) 154 Decomposable Mandrel 162 Mandrel for forming outer container

Claims

1. An inner container forming step involves forming an inner container by attaching an intermediate member made of fiber-reinforced thermoplastic resin to the outer surface of a mandrel for forming the inner container, An outer container component forming step involves attaching the intermediate member to the outer surface of the mandrel for forming the outer container to form a plurality of outer container component pieces for forming an outer container that is larger than the inner container, An outer container forming step involves arranging a plurality of the outer container components on the outside of the inner container and connecting the outer container components to each other, and connecting the inner container to any of the outer container components with a boss, thereby forming the outer container on the outside of the inner container, A vacuum step to create a vacuum in the space between the inner container and the outer container, Having, A method for manufacturing liquefied gas containers.

2. In the inner container forming step, the tape-shaped intermediate member made of molten thermoplastic resin is wrapped around the outer surface of the inner container forming mandrel to form an inner container component in which the intermediate members are laminated. In the outer container component forming step, the tape-shaped intermediate member, which is made of molten thermoplastic resin, is wrapped around the outer surface of the mandrel for forming the outer container to form the outer container component in which the intermediate members are laminated. A method for manufacturing a liquefied gas container according to claim 1.

3. In the inner container formation step, a tape-shaped intermediate member made of molten thermoplastic resin is wrapped around the outer surface of a disassemblable mandrel consisting of multiple pieces, and after the thermoplastic resin has solidified, the disassemblable mandrel is disassembled, and the pieces are removed from inside the wrapped intermediate member to form the inner container. A method for manufacturing a liquefied gas container according to claim 1.

4. The inner container forming step includes a gas barrier layer forming step in which a gas barrier layer is formed in the middle portion in the thickness direction of the intermediate member which is stacked in multiple layers. A method for manufacturing a liquefied gas container according to claim 2 or claim 3.

5. An outer container made of fiber-reinforced thermoplastic resin, An inner container, disposed inside the outer container and made of a fiber-reinforced thermoplastic resin having gas barrier properties, for storing liquefied gas, A boss is formed which connects the inner container and the outer container, and which has an opening in the inner container for the liquefied gas to enter and exit, Equipped with, The space between the outer container and the inner container is a vacuum-insulated space. The inner container has a gas barrier layer sandwiched inside the fiber-reinforced thermoplastic resin. Liquefied gas container.

6. An outer container made of fiber-reinforced thermoplastic resin, An inner container, disposed inside the outer container and made of a fiber-reinforced thermoplastic resin having gas barrier properties, for storing liquefied gas, A boss is formed which connects the inner container and the outer container, and which has an opening in the inner container for the liquefied gas to enter and exit, Equipped with, The space between the outer container and the inner container is a vacuum-insulated space. The boss is provided with a suction port that connects to the vacuum-insulated space. Liquefied gas container.

7. The boss is provided with a suction port that connects to the vacuum-insulated space. The liquefied gas container according to claim 5.

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