Sealing device

Abstract

The present invention provides a sealing device (1) that is disposed between two members (2, 3) facing each other, and that seals a space between the two members (2, 3). The sealing device (1) includes a seal body part (11) that is in contact with the space, and in the seal body part (11): the tensile strength, as measured in accordance with the specification of JIS K 6251:2017, is 10 MPa or more; the elongation at break, as measured in accordance with the specification of JIS K 6251:2017, is 200% or more; the TR10 temperature in a low-temperature elastic recovery test, as measured in accordance with the specification of JIS K 6261-4:2017, is -40°C or lower; and the compression set after 70 hours at 100°C, as measured in accordance with the specification of JIS K 6262:2013 in a G25 O-ring shape described in the specification of JIS B 2401-1:2012, is 40% or less.

Description

Technical Field

[0001] The present invention relates to a sealing device.

Background Art

[0002] In October 2020, the Japanese government declared the achievement of carbon neutrality, which aims to reduce greenhouse gas emissions to zero by 2050. In terms of raw materials, the switch from petroleum resources to plant resources that absorb carbon dioxide can contribute to carbon neutrality. As a plant resource, natural rubber made from sap is excellent in mechanical strength and cold resistance, and thus is beneficial for applications to materials that require high sealing performance. Examples of applications that can utilize the properties of such natural rubber include hydrogen seal materials.

[0003] In a hydrogen society, which is expected as a means of decarbonization, carbon dioxide is not emitted during energy use. Although hydrogen stations and fuel cell vehicles have already been put into practical use towards the realization of a hydrogen society, a sealing technology that can safely manage hydrogen without leakage under high pressure and in a wide temperature range is required. Therefore, the combination of hydrogen applications and natural rubber brings a synergistic decarbonization effect, and furthermore, it can be expected to suppress cracking under high pressure and improve the reduction of elasticity (cold resistance) at low temperatures in seal products.

[0004] However, generally, diene rubbers such as natural rubber tend to undergo thermal degradation. When natural rubber is compressed and exposed to hot air for a long time, stress relaxation due to oxidative decomposition occurs, and permanent strain remains after compression release. Such a phenomenon is fatal for seal products that seal fluids with the resilience of rubber. Therefore, in order to apply natural rubber to hydrogen seal materials, it is necessary to improve the compression set resistance in hot air.

[0005] Patent Document 1 describes a sealing material for a high-pressure hydrogen container of a fuel cell vehicle that can withstand fluctuations in pressure or temperature, and natural rubber is exemplified as one type of applicable rubber. However, in Patent Document 1, since the sealing performance under a high-temperature hydrogen atmosphere rather than a high-temperature air atmosphere is targeted, improvement of the compression set resistance of natural rubber in high-temperature air is not mentioned. Also, the exposure time of high-temperature hydrogen gas is relatively short at 1 hour, and furthermore, the compounding information of rubber materials capable of achieving desired performance is not described.

[0006] Therefore, it is necessary to study a sealing material made of natural rubber that has high mechanical strength under high pressure, exhibits excellent cold resistance, and can further exhibit excellent compression set resistance in high-temperature air for a long period of time.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention provides a sealing device that exhibits high mechanical strength under high pressure, and furthermore, is excellent in cold resistance in a low-temperature range and compression set resistance in a high-temperature range.

Means for Solving the Problems

[0009] The sealing device according to an embodiment of the present invention is a sealing device disposed between two members facing each other to seal the space between the two members, and includes a seal main body portion in contact with the space. In the seal main body portion, the tensile strength measured in accordance with the provisions of JIS K 6251:2017 is 10 MPa or more, the elongation at break measured in accordance with the provisions of JIS K 6251:2017 is 200% or more, the temperature of TR10 in the low-temperature elastic recovery test measured in accordance with the provisions of JIS K 6261-4:2017 is -40°C or lower, and the compression set after 70 hours at 100°C measured in accordance with the provisions of JIS K 6262:2013 in the shape of a G25 O-ring described in the provisions of JIS B 2401-1:2012 is 40% or lower.

[0010] In one embodiment of the present invention, the seal main body portion is annular.

[0011] In one embodiment of the present invention, the seal main body portion is held by a backup ring.

[0012] In one embodiment of the present invention, the cross-sectional shape of the seal main body portion is a protruding shape.

[0013] In one embodiment of the present invention, the seal main body portion is provided on a plate-shaped base material, and the base material is a metal or carbon plate.

[0014] In one embodiment of the present invention, the base material and the seal main body portion are adhered by an adhesive contained in the seal main body portion.

[0015] In one embodiment of the present invention, the seal main body portion is in contact with hydrogen gas.

[0016] In one embodiment of the present invention, the seal main body portion is in contact with liquid hydrogen.

[0017] In one embodiment of the present invention, the sealing device is a sealing device for use in a hydrogen energy system.

[0018] A sealing device according to another embodiment of the present invention is a sealing device disposed between two members facing each other to seal the space between the two members, and includes a seal body portion in contact with the space. The seal body portion is a vulcanized molded product of a rubber composition containing (A) a natural rubber component selected from natural rubber and epoxidized natural rubber having an epoxidation degree of 1% or more and less than 50%, (B) a filler selected from carbon black and silica, (C) an organic peroxide-based crosslinking agent, and optionally (D) a silane coupling agent (provided that when the filler is carbon black, the rubber composition contains epoxidized natural rubber having an epoxidation degree of 1% or more and less than 50%, and when the filler is silica, the rubber composition further contains a silane coupling agent).

[0019] In one embodiment of the present invention, the rubber composition further contains at least one additive selected from the group consisting of (E) a crosslinking accelerator, an auxiliary agent, and an antioxidant.

Advantages of the Invention

[0020] According to the present invention, it is possible to provide a sealing device that exhibits high mechanical strength under high pressure, and further has excellent cold resistance in a low temperature range and excellent compression set resistance in a high temperature range.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

BEST MODE FOR CARRYING OUT THE INVENTION

[0022] Hereinafter, the sealing device according to the embodiment of the present invention will be described in detail with reference to the drawings. The room temperature described below is in the range of 23°C ± 2°C.

[0023] <Sealing device> The sealing device according to the present embodiment is a sealing device disposed between two members facing each other and sealing the space between the two members, and includes a seal body portion in contact with the space. The sealing device according to the present embodiment is preferably used in a hydrogen energy system. At this time, the seal body portion is in contact with hydrogen gas or liquid hydrogen, and the sealing device is used as a hydrogen gas seal or a liquid hydrogen seal.

[0024] <First Embodiment> FIG. 1 is an example of an embodiment of a sealing device including such a seal body portion. The sealing device 1 shown in FIG. 1 is mounted in a mounting groove (mounting portion) 4 provided in one of the two members 2 and 3 facing each other, and is in close contact with the other member 3, thereby sealing between the two members 2 and 3. The sealing device 1 includes a seal ring (rubber ring-shaped packing) 11 made of a rubber-like elastic body, a first backup ring (backup ring) 21 disposed on the low-pressure side L of the seal ring 11, and a second backup ring 31 disposed between the seal ring 11 and the first backup ring 21. The two members 2 and 3 are, for example, high-pressure hydrogen pipes for a fuel cell connected to each other, and the seal housing portion of the other pipe member 3 is disposed on the outer peripheral side of the seal housing portion of one pipe member 2. The sealing device 1 is mounted in an annular mounting groove 4 provided on the outer peripheral surface of the seal housing portion of one pipe member 2 and is in close contact with the inner peripheral surface of the seal housing portion of the other pipe member 3. The sealing fluid is high-pressure hydrogen gas flowing from the high-pressure side H to the low-pressure side L.

[0025] As the first backup ring 21, a backup ring made of nylon (trade name) is used. Nylon is one of the resin materials that are difficult to permeate gas. Further, as the second backup ring 31, a backup ring made of a material softer than the first backup ring 21 such as PTFE resin, for example, is used. Both backup rings 21 and 31 are often endless rings with one circumferential location cut to facilitate incorporation, but in consideration of gas leakage, it is preferably an endless type without a cut.

[0026] The seal ring 11 corresponds to the seal main body portion of the sealing device according to the present invention. The seal ring 11 is formed in an annular shape, and the seal ring 11 is held by the first and second backup rings 21 and 31. The material of the seal ring 11 is the same as the material forming the seal main body portion described later, and the seal ring 11 exhibits the characteristics of the seal main body portion described later.

[0027] The mounting groove 4 is basically formed as a space having a rectangular cross section, but among the groove bottoms, the high-pressure side mounting portion 4a for mounting the seal ring 11 is formed in a planar shape forming a cylindrical surface. Further, the low-pressure side mounting portions 4b for mounting the first and second backup rings 21 and 31 continuous with the low-pressure side L of the high-pressure side mounting portion 4a are formed in an inclined surface shape forming a conical surface so as to gradually narrow the interval (radial interval) between the two members 2 and 3 from the high-pressure side H to the low-pressure side L, that is, so as to gradually shallower the groove depth of the mounting groove 4, and is formed as an inclined bottom surface 4c.

[0028] Further, the first and second backup rings 21 and 31 mounted on the low-pressure side mounting portion 4b are each basically formed in a rectangular cross section, but the inner peripheral surface thereof is formed in an inclined surface shape forming a conical surface so as to gradually expand the inner diameter dimension from the high-pressure side H to the low-pressure side L corresponding to the inclined bottom surface 4c, and is formed as inclined surfaces 21a and 31a.

[0029] In the sealing device 1 configured as described above, when pressure P acts from the right side in FIG. 1, the seal ring 11 is pressed against the second backup ring 31 on its low-pressure side. This second backup ring 31 is formed of PTFE resin, which is softer than the first backup ring 21 made of nylon. Therefore, it is possible to suppress damage to the seal ring 11 caused by repeated pressing against the hard material during the generation of alternating pressure or the like. Further, since the second backup ring 31 is formed of PTFE resin, which is a soft material, extrusion is likely to occur. However, the first backup ring 21 formed of nylon, which is a hard material, prevents extrusion.

[0030] Further, the mounting groove 4 is provided with an inclined bottom surface 4c that gradually narrows the interval between the two members 2 and 3 from the high-pressure side H to the low-pressure side L. Inclined surfaces 21a and 31a corresponding to the inclined bottom surface 4c are provided on the inner peripheral surfaces of both backup rings 21 and 31, respectively. Therefore, when the sealed fluid pressure acts on both backup rings 21 and 31 via the seal ring 11, both backup rings 21 and 31 are compressed in such a way that they are pushed into the narrow area and closely adhere to the mating surface. Therefore, due to the compression phenomenon of both backup rings 21 and 31 caused by the inclined surfaces 21a and 31a, not only is it more difficult for the seal ring 11 to protrude, but it is also expected that when the high-pressure hydrogen gas, which is the sealed fluid, cannot be sealed only by the seal ring 11, the backup rings 21 and 31 can seal it.

[0031] Further, the backup ring 21 is formed of nylon, which is difficult to permeate gas. Therefore, also from this point, it can be expected to effectively reduce the leakage caused by the high-pressure hydrogen gas, which is the sealed fluid, permeating through the backup ring 21. Furthermore, since the radial width dimension of the backup ring 21 is smaller than the radial width dimension of the second backup ring 31, the permeation area is set small. Therefore, also from this point, it is possible to effectively seal the high-pressure hydrogen gas, which is the sealed fluid.

[0032] In addition, the sealing device 1 according to the present embodiment may be applicable not only to a cylindrical gap between two members but also to a planar gap, i.e., a gap between end faces. FIG. 2 shows an example of an embodiment of such a sealing device. In the lower sealing device 1A in FIG. 2, first to second backup rings 21 and 31 are arranged in the axial direction to seal a cylindrical gap between one piping member 2 and the other piping member 3. In the upper sealing device 1B in FIG. 2, first to second backup rings 21 and 31 are arranged in the radial direction to seal a planar gap between one piping member 2 and the other piping member 3. By arranging them in such a double configuration, it is possible to further reduce leakage to the outside.

[0033] <Second Embodiment> FIG. 3 shows an example of a sealing device according to another embodiment of the present invention. The sealing device 100 shown in FIG. 3 is a seal component for a separator laminated on both sides of an electrolyte membrane / electrode assembly (hereinafter referred to as MEA) in a general fuel cell, that is, a cell seal for a fuel cell. Such a cell seal for a fuel cell is disposed between a separator and an MEA, which are two members facing each other, to seal the space between the separator and the MEA (not shown). In the separator of a fuel cell, it is necessary to supply a fluid for a fuel cell (such as a fuel gas containing hydrogen or an oxidant gas containing oxygen) to the MEA so as not to leak to the outside. An endless gasket serves to seal (seal) such a fluid for a fuel cell within a space surrounded by the gasket.

[0034] The sealing device 100 shown in Fig. 3 has an endless gasket 102 made of an elastic material and extending along the surface of a plate-like base material 101 formed around the vent hole 101a on the surface of the base material 101. Fig. 4 shows a schematic cross-section of the sealing device 100 along the line AA' of Fig. 3, and the gasket 102 is formed as four protruding portions protruding from the surface of the base material 101. As shown in Fig. 4, the gasket 102 has a base portion 102a adhered to the surface of the base material 101 and a seal lip portion 102b protruding in a mountain shape from the base portion 102a. Incidentally, on the line AA' of Fig. 3, there is a location (not shown) where the molding material of the gasket 102 flows in and out during the molding of the gasket 102.

[0035] As the base material 101, for example, a metal plate such as stainless steel or a thin plate such as a carbon plate is used. The base material 101 and the gasket 102 are adhered via an adhesive layer or by an adhesive contained in the gasket 102. Further, the sealing device 100 may be an integrally molded cell seal in which an endless gasket 102 made of an elastic material and extending along the surface of a plate-like base material 101 is integrally molded. As the base material 101 of such an integrally molded cell seal, it is a member included in the cell structure of a fuel cell integrally molded with the gasket 102, and examples include a separator, an MEA, a gas diffusion layer (GDL), and the like.

[0036] The gasket 102 corresponds to the seal main body portion of the sealing device according to the present invention. As shown in Fig. 4, the cross-sectional shape of the gasket 102 is a protruding shape. The material of the gasket 102 is the same as the material forming the seal main body portion described later, and the gasket 102 exhibits the characteristics of the seal main body portion described later.

[0037] <Seal main body portion> The seal main body portion of the sealing device according to this embodiment is a vulcanized molded product of a rubber composition containing (A) a natural rubber component selected from natural rubber and epoxidized natural rubber having an epoxidation degree of 1% or more and less than 50%, (B) a filler selected from carbon black and silica, (C) an organic peroxide crosslinking agent, and optionally (D) a silane coupling agent. However, when the filler is carbon black, the rubber composition contains epoxidized natural rubber having an epoxidation degree of 1% or more and less than 50%, and when the filler is silica, the rubber composition further contains a silane coupling agent. Natural rubber is considered to undergo an oxidative decomposition reaction starting from a diene structure (C=C bond) in a high-temperature air atmosphere. Therefore, in a rubber composition containing a natural rubber component filled with carbon black, by appropriately using epoxidized natural rubber, compression set can be suppressed and the compression set resistance in high-temperature air can be improved. Also, by adding a silane coupling agent to a rubber composition containing a natural rubber component filled with silica, even if the natural rubber is not epoxidized, excellent cold resistance can be maintained while improving the compression set resistance in high-temperature air.

[0038] Thus, when manufacturing the seal main body portion, by using the above-described specific rubber composition, even with natural rubber as the main raw material, it is possible to obtain a seal main body portion that is difficult to crack even under high pressure, has high elastic recovery in the low-temperature range, and has a small compression set in the high-temperature range, which are the required characteristics for a hydrogen seal material. As a result, a sealing device can be realized that exhibits high mechanical strength under high pressure and is excellent in cold resistance in the low-temperature range and compression set resistance in the high-temperature range.

[0039] The shape of the seal main body portion is not particularly limited and can be any shape according to the application. For example, it may be a sheet-like seal member such as a square, rectangular, or disk-shaped cross-sectional shape, an annular seal member such as an O-ring or a square ring, or these annular portions may be formed in a part of the seal main body portion.

[0040] (A) Natural rubber component As the natural rubber component, natural rubber which has not been chemically modified at all or natural rubber which has been epoxidized with an epoxidation degree of 1% or more and less than 50% in the diene portion is used. Natural rubber is rubber refined from the sap (latex) of natural trees, and is a diene-based rubber different from synthetic rubber manufactured by chemical synthesis using petroleum, naphtha, etc. as raw materials. The diene portion of natural rubber can be epoxidized by the reaction of formic acid and hydrogen peroxide water. The epoxidized natural rubber has an epoxidation degree of 1% or more and less than 50%, preferably has an epoxidation degree of 10% or more and 40% or less, and more preferably has an epoxidation degree of 20% or more and 30% or less.

[0041] Natural rubber and epoxidized natural rubber may be used alone or in combination of two or more. By using such natural rubber, the mechanical properties of the seal body portion can be improved. Also, natural rubber and epoxidized natural rubber may be commercially available products. Examples of commercially available products of natural rubber and epoxidized natural rubber include natural rubber "RSS No. 1" (imported by Toyo Chemical Plus) and natural rubber "ENR25" (imported by Sanyo Trading) having an epoxidation degree of 25%.

[0042] (B) Filler A filler is compounded in the rubber composition. By including a filler in the rubber composition, the mechanical strength and compression set properties of the resulting vulcanizate can be improved. As the filler, carbon black and silica, which are common as reinforcing materials, are used. The filler may be used alone or in combination of two or more.

[0043] Carbon black can be appropriately selected from known materials. For example, hard carbon blacks such as super abrasion furnace (SAF) carbon black, intermediate super abrasion furnace (ISAF) carbon black, high abrasion furnace (HAF) carbon black, and easy processing channel (EPC) carbon black, and soft carbon blacks such as extra conductive furnace (XCF) carbon black, fast extruding furnace (FEF) carbon black, general purpose furnace (GPF) carbon black, high modulus furnace (HMF) carbon black, semi-reinforcing furnace (SRF) carbon black, fine thermal (FT) carbon black, and medium thermal (MT) carbon black can be mentioned. Examples of commercially available carbon blacks include "Vulcan (registered trademark) 3L" (HAF carbon) manufactured by Cabot Corporation. The content of carbon black is not particularly limited, but it is preferably 1 part by mass or more and 100 parts by mass or less, and more preferably 25 parts by mass or more and 75 parts by mass or less, based on 100 parts by mass of the natural rubber component. Carbon black may be used alone or in combination of two or more kinds.

[0044] Silica can be appropriately selected from known materials, but it is preferably one with good kneading workability. Commonly used silica includes dry-process silica produced by thermal decomposition of halogenated silicic acid or organosilicon compounds, or by heating and reducing silica sand and oxidizing vaporized SiO in air, and wet-process silica produced by thermal decomposition of sodium silicate, etc. Examples of commercially available silica include "Ultrasil (registered trademark) 360" manufactured by Evonik Japan Co., Ltd. The content of silica is not particularly limited, but it is preferably 1 to 100 parts by mass, more preferably 25 to 75 parts by mass, based on 100 parts by mass of the natural rubber component. Silica may be used alone or in combination of two or more.

[0045] (C) Organic peroxide crosslinking agent The organic peroxide crosslinking agent is used as a crosslinking agent that forms peroxide crosslinking of the natural rubber component. By using an organic peroxide crosslinking agent as the crosslinking agent, excellent compression set resistance is imparted to the seal body part. Examples of the organic peroxide crosslinking agent include dicumyl peroxide, cumene hydroperoxide, p-methane hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, di-tert-butyl peroxide, benzoyl peroxide, m-toluoyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-bis(tert-butylperoxy)-3-hexyne, 1,3-bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, tert-butyl peroxybenzoate, tert-butyl peroxylaurate, di(tert-butylperoxy)adipate, di(2-ethoxyethyl peroxy)dicarbonate, bis(4-tert-butylcyclohexyl) peroxydicarbonate, etc. Among these, dicumyl peroxide is preferred.

[0046] As a commercially available organic peroxide crosslinking agent, for example, "Perk Mill (registered trademark) D" manufactured by NOF Corporation can be used. The content of the organic peroxide crosslinking agent is preferably 0.1 part by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 5 parts by mass or less, based on 100 parts by mass of the natural rubber component. The organic peroxide crosslinking agent may be used alone or in combination of two or more.

[0047] (D) Silane coupling When the rubber composition contains silica as a filler, a silane coupling agent is further compounded into the rubber composition. As the silane coupling agent, a silane coupling having a mercapto group is preferable, and examples thereof include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldiethoxymethoxysilane, 3-mercaptopropyltripropoxysilane, 3-mercaptopropyldipropoxymethoxysilane, 3-mercaptopropyltributoxysilane, 3-mercaptopropyldibutoxymethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyldimethylmethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-mercaptopropyldimethylethoxysilane, 3-mercaptopropylmethyldipropoxysilane, 3-mercaptopropylpropoxydimethylsilane, 3-mercaptopropylmethyldiisopropoxysilane, 3-mercaptopropylisopropoxydimethylsilane, 3-mercaptopropylmethyldibutoxysilane, 3-mercaptopropyldimethylbutoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, mercaptomethyltrimethoxysilane, mercaptomethyltriethoxysilane, and the like.

[0048] As commercially available silane coupling agents, for example, "KBM-803" manufactured by Shin-Etsu Silicone Co., Ltd. can be used. The content of the silane coupling agent is preferably 0.1 part by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 5 parts by mass or less, based on 100 parts by mass of the natural rubber component. The silane coupling agent may be used alone or in combination of two or more.

[0049] (E) Other additives The rubber composition may further contain other compounding components in addition to the above components, if necessary. Examples of other compounding components include various additives such as vulcanization accelerators, plasticizers, antioxidants, auxiliaries, lubricants, adhesives, lubricants, flame retardants, antifungal agents, antistatic agents, etc. These additives may be used alone or in combination of two or more. Also, the compounding amounts thereof are not particularly limited as long as they do not inhibit the object and effect of the present invention, and appropriate amounts according to the compounding purpose can be compounded as appropriate.

[0050] <Method for manufacturing the seal body part> The method for manufacturing the seal body part is not particularly limited. For example, after appropriately compounding the natural rubber component, filler, and organic peroxide-based crosslinking agent described above, and further, if necessary, the silane coupling agent and optional various additives at a predetermined ratio, a rubber composition is manufactured by kneading using a kneader such as a single-screw extruder, twin-screw extruder, roll, Banbury mixer, kneader, high-shear mixer, etc. Incidentally, before kneading, pre-kneading, preliminary kneading, etc. may be performed if necessary.

[0051] Furthermore, a vulcanized molded product having the shape of the seal body part can be manufactured by vulcanizing and molding the obtained rubber composition. The vulcanizing and molding of the rubber composition is generally carried out by pressure vulcanization at about 150 to 230 °C for about 0.5 to 30 minutes using an injection molding machine, a compression molding machine, etc. Also, after such primary vulcanization (pressure vulcanization), secondary vulcanization may be performed if necessary to ensure that the inside of the vulcanized molded product is vulcanized. Secondary vulcanization can generally be carried out by oven heating, steam heating, hot air heating, etc. at about 150 to 250 °C for about 0.5 to 24 hours.

[0052] (Mechanical strength) In the seal body portion of the sealing device according to the present embodiment, the tensile strength measured in accordance with the provisions of JIS K6251:2017 (Japanese Industrial Standard created based on ISO37 (5th edition, 2011) with technical content changes) (test piece shape: dumbbell shape No. 6, speed: 500 mm / min, distance between gauge marks: 20 ± 0.5 mm, atmosphere: air, test temperature: tensile strength measured at room temperature) is 10 MPa or more, and preferably 15 MPa or more. Further, in the seal body portion, the elongation at break measured in accordance with the provisions of JIS K 6251:2017 (test piece shape: dumbbell shape No. 6, speed: 500 mm / min, distance between gauge marks: 20 ± 0.5 mm, atmosphere: air, test temperature: elongation at break measured at room temperature) is 200% or more, and preferably 300% or more. Since the seal body portion has a tensile strength of 10 MPa or more and an elongation at break of 200% or more, it is possible to provide a sealing device including a seal body portion that exhibits high mechanical strength even under high pressure.

[0053] (Cold resistance) In the seal body portion of the sealing device according to the present embodiment, the temperature of TR10 in the low-temperature elastic recovery test (TR test) measured in accordance with the provisions of JIS K6261-4:2017 (Japanese Industrial Standard created based on ISO2921 (5th edition, 2011) with technical content changes) (test piece shape: I-shaped as described in the provisions of JIS K6261-4:2017, heat medium: ethanol, test temperature: temperature of TR10 in the low-temperature elastic recovery test (TR test) measured under the conditions of -70°C to 23°C) is -40°C or lower, and preferably -60°C or lower. Since the temperature at TR10 is -40°C or lower, it is possible to provide a sealing device including a seal body portion that is excellent in cold resistance in a low-temperature range.

[0054] (Compression set resistance) In the seal body portion of the sealing device according to the present embodiment, the compression set after 70 hours at 100°C measured in accordance with the provisions of JIS K 6262:2013 (Japanese Industrial Standard created based on ISO815-1 and ISO815-2 (both the 1st edition in 2008) with technical content changes) in the shape of a G25 O-ring described in the provisions of JIS B 2401-1:2012 (Japanese Industrial Standard created based on ISO3601-1 (4th edition in 2008) with technical content changes) (compression plate: smooth stainless steel plate, test piece shape: G25 O-ring described in the provisions of JIS B 2401-1:2012, spacer thickness: 2.30 mm, compression ratio: 25%, atmosphere: air, test temperature: 100°C, exposure time: 70 hours, standing condition after release: measured under the condition of 30 minutes at room temperature) is 40% or less, and preferably 35% or less. Since the compression set under such conditions is 40% or less, a sealing device provided with a seal body portion excellent in compression set resistance in a high temperature range can be provided.

[0055] Based on the above embodiments, the present invention relates to the following [1] to [7]. [1] A sealing device disposed between two members facing each other to seal the space between the two members, comprising a seal body portion in contact with the space, wherein in the seal body portion, the tensile strength measured in accordance with the provisions of JIS K 6251:2017 is 10 MPa or more, the elongation at break measured in accordance with the provisions of JIS K 6251:2017 is 200% or more, the temperature of TR10 in the low temperature elastic recovery test measured in accordance with the provisions of JIS K 6261-4:2017 is -40°C or less, and the compression set after 70 hours at 100°C measured in accordance with the provisions of JIS K 6262:2013 in the shape of a G25 O-ring described in the provisions of JIS B 2401-1:2012 is 40% or less. [2] The sealing device according to [1] above, wherein the seal body portion is annular. [3] The sealing device according to [1] or [2] above, wherein the seal main body is held by a backup ring. [4] The sealing device according to [1] above, wherein the cross-sectional shape of the seal main body is a protruding shape. [5] The sealing device according to [4] above, wherein the seal main body is provided on a plate-like base material, and the base material is a metal or carbon plate. [6] The sealing device according to [5] above, wherein the base material and the seal main body are adhered by an adhesive contained in the seal main body. [7] The sealing device according to any one of [1] to [6] above, wherein the seal main body is in contact with hydrogen gas. [8] The sealing device according to any one of [1] to [6] above, wherein the seal main body is in contact with liquid hydrogen. [9] The sealing device according to any one of [1] to [8] above, for use in a hydrogen energy system.

[10] A sealing device disposed between two members facing each other to seal the space between the two members, comprising a seal main body in contact with the space, wherein the seal main body is a vulcanized molded product of a rubber composition containing (A) a natural rubber component selected from natural rubber and epoxidized natural rubber having an epoxidation degree of 1% or more and less than 50%, (B) a filler selected from carbon black and silica, (C) an organic peroxide-based crosslinking agent, and optionally (D) a silane coupling agent (however, when the filler is carbon black, the rubber composition contains epoxidized natural rubber having an epoxidation degree of 1% or more and less than 50%, and when the filler is silica, the rubber composition further contains a silane coupling agent).

[11] The sealing device according to

[10] above, wherein the rubber composition further contains at least one additive selected from the group consisting of (E) a vulcanization accelerator, an auxiliary agent, and an antioxidant.

[0056] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and includes all aspects included in the concept and scope of claims of the present invention, and can be variously modified within the scope of the present invention.

Examples

[0057] Next, examples of the present invention will be described, but the present invention is not limited to these examples.

[0058] (Example 1) 100 parts by mass of natural rubber having an epoxidation degree of 25% (``ENR25'', imported by Sanyo Trading) was put into a kneading and extruding apparatus (``Laboplastmill 30C150'', manufactured by Toyo Seiki Co., Ltd.), and kneaded at 50 ° C for 15 minutes. Then, 50 parts by mass of filler A (carbon black: trade name ``Vulcan (registered trademark) 3L'', manufactured by Cabot Japan), 2.5 parts by mass of crosslinking agent A (dicumyl peroxide: trade name ``Perkmill (registered trademark) D'', manufactured by NOF Corporation), 5 parts by mass of auxiliary agent A (zinc white: trade name ``zinc oxide'', manufactured by Sho Do Chemical Industry Co., Ltd.), 1 part by mass of auxiliary agent B (stearic acid: trade name ``DTST'', manufactured by Miyoshi Oil & Fat Co., Ltd.) and 2 parts by mass of antioxidant (2,2,4-trimethyl-1,2-dihydroquinoline polymer: trade name ``No Crack 224'', manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) were further added and kneaded at 50 ° C for 15 minutes to produce a rubber sheet. Next, the obtained rubber sheet was put into a roll kneader (``LABORTORY MILL'', manufactured by Kansai Roll Co., Ltd.), and the rubber sheet was passed through 5 times with a roll gap of 1.5 to 2.5 mm, and then passed through 10 times with a roll gap of 1 mm to produce a rubber composition.

[0059] <Preparation of Test Pieces for Measuring Mechanical Strength and Cold Resistance> Regarding the obtained rubber composition, using a press machine (“80TON Press”, manufactured by Kitanshi Kogyo Co., Ltd.), crosslinking was carried out by heating press at 170 °C and crosslinking for 1.5 times the t90 (90% crosslinking time) to perform pressure vulcanization (primary vulcanization), and test piece A was produced.

[0060] <Preparation of Test Piece for Compression Set Measurement> Regarding the obtained rubber composition, using a press machine (“50-ton KV Press”, manufactured by Koda Shosha Co., Ltd.), crosslinking was carried out by heating press at 170 °C and crosslinking for 1.5 times the t90 (90% crosslinking time) to perform pressure vulcanization (primary vulcanization), and test piece B was produced.

[0061] <Tensile Strength and Elongation at Break> Regarding test piece A, using a tensile testing machine (“Strograph (registered trademark) AE”, manufactured by Toyo Seiki Co., Ltd.), in accordance with the provisions of JIS K 6251:2017, the tensile strength and elongation at break were measured under the following test conditions. The results are shown in Table 1.

[0062] [Test Conditions] · Test piece shape: dumbbell shape No. 6 (The test piece has a dumbbell shape as shown in Figure 5, S is the gauge mark, D is the initial gauge length, and T represents the parallel part. In the dumbbell shape No. 6, D = 20 ± 0.5 mm and the thickness of T = 2.0 ± 0.2 mm.) · Speed: 500 mm / min · Atmosphere: air · Test temperature: room temperature

[0063] <Cold Resistance> Regarding test piece A, using a TR tester (“No. 145-L”, manufactured by Yasuda Seiki Co., Ltd.), in accordance with the provisions of JIS K6261-4:2017, a low-temperature elastic recovery test (TR test) was carried out under the following test conditions, and the temperature at TR10 was measured. The results are shown in Table 1.

[0064] [Test Conditions] · Test piece shape: I-shaped as described in the provisions of JIS K6261-4:2017 · Heat medium: Ethanol · Test temperature: -70°C to 23°C

[0065] <Compression set resistance> For test piece B, the compression set was measured under the following test conditions in accordance with the provisions of JIS K 6262:2013. The results are shown in Table 1.

[0066] [Test conditions] · Compression plate: Smooth stainless steel plate · Test piece shape: G25 O-ring described in the provisions of JIS B 2401-1:2012 (Figure 6 is a schematic diagram showing the cross-section of the O-ring used for the test piece, where d1 represents the inner diameter and d2 represents the thickness. For the G25 O-ring, d1 = 24.4 ± 0.25 mm and d2 = 3.1 ± 0.10 mm.) · Spacer thickness: 2.30 mm · Compression ratio: 25% · Atmosphere: Air · Test temperature: 100°C · Exposure time: 70 hours · Standing condition after release: 30 minutes at room temperature

[0067] (Example 2) Instead of natural rubber having an epoxidation degree of 25%, natural rubber ("RSS No. 1", imported by Toyo Chemical Plus) was used, and instead of filler A, filler B (silica: trade name "Ultrasil® 360", manufactured by Evonik Japan Co., Ltd.) was used. Further, 1 part by mass of a silane coupling agent (mercapto group-containing silane coupling agent: trade name "KBM-803", manufactured by Shin-Etsu Silicone Co., Ltd.) was blended. Rubber compositions and each test piece A and B were prepared in the same manner as in Example 1, and the above measurements were performed. The results are shown in Table 1.

[0068] (Comparative Example 1) Instead of natural rubber with an epoxidation degree of 25%, natural rubber ("RSS No. 1", imported by Toyo Chemical Plus) was used. Instead of crosslinking agent A, 0.5 part by mass of crosslinking agent B (sulfur: trade name "Colloidal Sulfur A", manufactured by Tsurumi Chemical Industry Co., Ltd.) was used. Furthermore, 1.5 parts by mass of crosslinking accelerator A (N-cyclohexyl-2-benzothiazole sulfenamide: trade name "Nocceler (registered trademark) CZ-G", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) and 1 part by mass of crosslinking accelerator B (tetramethylthiuram disulfide: trade name "Nocceler (registered trademark) TT-P", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) were blended. Also, when preparing each test piece A and B, a rubber composition and each test piece A and B were prepared in the same manner as in Example 1 except that the crosslinking temperature was changed from 170 °C to 150 °C, and the above measurements were performed. The results are shown in Table 1.

[0069] (Comparative Example 2) A rubber composition and each test piece A and B were prepared in the same manner as in Example 1 except that natural rubber ("RSS No. 1", imported by Toyo Chemical Plus) was used instead of natural rubber with an epoxidation degree of 25%, and the above measurements were performed. The results are shown in Table 1.

[0070] (Comparative Example 3) A rubber composition and each test piece A and B were prepared in the same manner as in Example 1 except that natural rubber with an epoxidation degree of 50% ("ENR50", imported by Sanyo Trading) was used instead of natural rubber with an epoxidation degree of 25%, and the above measurements were performed. The results are shown in Table 1.

[0071] (Comparative Example 4) A rubber composition and each test piece A and B were prepared in the same manner as in Example 2 except that no silane coupling agent was blended, and the above measurements were performed. The results are shown in Table 1.

[0072]

Table 1

[0073] Each component shown in Table 1 above is as follows. In addition, the values of each component in Table 1 above represent "parts by mass". · Natural rubber: Trade name "RSS No. 1", imported by Toyotsu Chemical Plus · Natural rubber with 25% epoxidation degree ("ENR25", imported by Sanyo Trading) · Natural rubber with 50% epoxidation degree ("ENR50", imported by Sanyo Trading) · Filler A: Carbon black (Trade name "Vulcan® 3L", manufactured by Cabot Japan) · Filler B: Silica (Trade name "Ultrasil® 360", manufactured by Evonik Japan) · Crosslinking agent A: Dicumyl peroxide (Trade name "Perkmill® D", manufactured by NOF Corporation) · Crosslinking agent B: Sulfur (Trade name "Colloidal Sulfur A", manufactured by Tsurumi Chemical Industry) · Silane coupling agent: Mercapto group-containing silane coupling agent (Trade name "KBM-803", manufactured by Shin-Etsu Silicone) · Auxiliary agent A: Zinc oxide (Trade name "Zinc Oxide", manufactured by Shodo Chemical Industry) · Auxiliary agent B: Stearic acid (Trade name "DTST", manufactured by Miyoshi Oil & Fat) · Anti-aging agent: 2,2,4-Trimethyl-1,2-dihydroquinoline polymer (Trade name "No Crack 224", manufactured by Ouchi Shinko Chemical Industry)

[0074] As can be seen from Table 1, in Examples 1 and 2, the tensile strength was 10 MPa or more and the elongation at break was 200% or more, showing high mechanical strength even under high pressure. Also, in Examples 1 and 2, the temperature of TR10 in the low-temperature elastic recovery test was -40°C or lower, and furthermore, the compression set after 70 hours at 100°C was 40% or lower. Therefore, they were excellent in cold resistance in the low-temperature range and compression set resistance in the high-temperature range.

[0075] On the other hand, in Comparative Example 1 where a sulfur crosslinking agent was used as the crosslinking agent, the compression set was higher than 40%, indicating inferior compression set resistance. Similarly, in Comparative Example 2 where carbon black was used as the filler and unmodified natural rubber was used as the natural rubber component, the compression set was also higher than 40%, showing inferior compression set resistance. In Comparative Example 3 where carbon black was used as the filler and natural rubber with an epoxidation degree of 50% was used as the natural rubber component, although the compression set was 40% or less, the temperature of TR10 in the low-temperature elastic recovery test was higher than -40°C, indicating inferior cold resistance. Furthermore, in Comparative Example 4 where silica was used as the filler but no silane coupling agent was used, the compression set was higher than 40%, showing inferior compression set resistance.

Explanation of Reference Signs

[0076] 1, 1A, 1B Sealing device, 2 One member (pipe member), 3 The other member (pipe member), 4 Mounting groove, 4a High-pressure side mounting part, 4b Low-pressure side mounting part, 4c Inclined bottom surface, 11 Seal ring, 21 First backup ring (backup ring), 21a, 31a Inclined surface, 31 Second backup ring, 100 Sealing device, 101 Base material, 101a Vent hole, 102 Gasket, 102a Base part, 102b Seal lip part

Claims

1. A sealing device disposed between two members facing each other to seal the space between the two members, comprising a seal main body portion in contact with the space, wherein in the seal main body portion, the tensile strength measured in accordance with the provisions of JIS K 6251:2017 is 15 MPa or more, the elongation at break measured in accordance with the provisions of JIS K 6251:2017 is 300% or more, the temperature of TR10 in the low-temperature elastic recovery test measured in accordance with the provisions of JIS K 6261-4:2017 is -40°C or lower, and the compression set after 70 hours at 100°C measured in accordance with the provisions of JIS K 6262:2013 in the shape of the G25 O-ring described in the provisions of JIS B 2401-1:2012 is 40% or less. The sealing device is characterized by this.

2. The sealing device according to claim 1, wherein the seal main body portion is annular.

3. The sealing device according to claim 1 or 2, wherein the seal main body portion is held by a backup ring.

4. The sealing device according to claim 1, wherein the cross-sectional shape of the seal main body portion is a protruding shape.

5. The sealing device according to claim 4, wherein the seal main body portion is provided on a plate-shaped base material, and the base material is a metal or carbon plate.

6. The sealing device according to claim 5, wherein the base material and the seal main body portion are adhered by an adhesive contained in the seal main body portion.

7. The sealing device according to claim 1 or 2, wherein the seal main body portion is in contact with hydrogen gas.

8. The sealing device according to claim 1 or 2, wherein the seal main body portion is in contact with liquid hydrogen.

9. The sealing device according to claim 1 or 2 for use in a hydrogen energy system.

Images