Hydrogen refueling hose

Abstract

To provide a hydrogen filling hose having excellent hydrogen gas barrier, low-temperature durability and handleability.SOLUTION: A hydrogen filling hose comprises an inner layer, a reinforcing layer arranged outside the inner layer, and an outer layer arranged outside the reinforcing layer. The reinforcing layer comprises at least one layer made of organic fiber. The inner layer contains a polyamide elastomer containing a hard segment made of polyamide 11, and a soft segment made of polyether.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hose for hydrogen filling. More specifically, the present invention relates to a hose for filling a fuel cell vehicle or the like with hydrogen gas from a dispenser installed at a hydrogen station.

Background Art

[0002] In recent years, the development of fuel cell vehicles and the like has been actively carried out. Along with this, the development of a hose for filling a fuel cell vehicle or the like with hydrogen gas from a dispenser installed at a hydrogen station has also been promoted. For this hydrogen filling hose, hydrogen gas barrier properties, low-temperature durability, handling properties, and the like are required.

[0003] Japanese Patent Application Laid-Open No. 2021-66794 (Patent Document 1) discloses a high-pressure hydrogen hose including a gas barrier layer made of a polymer composition having an amide bond, characterized in that the elongation at upper yield point at 23°C is 9% or more and the product of strength and elongation at 23°C is 110 or more.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the high-pressure hydrogen hose described in Patent Document 1 does not always have sufficient low-temperature durability. The present invention provides a hydrogen filling hose excellent in hydrogen gas barrier properties, low-temperature durability, and handling properties.

Means for Solving the Problems

[0006] The present invention relates to a hydrogen filling hose comprising an inner layer, a reinforcing layer disposed outside the inner layer, and an outer layer disposed outside the reinforcing layer, wherein the reinforcing layer comprises at least one layer made of organic fibers, and the inner layer comprises a polyamide elastomer comprising a hard segment made of polyamide 11 and a soft segment made of polyether.

[0007] The present invention includes the following embodiments. [1] A hydrogen filling hose comprising an inner layer, a reinforcing layer disposed outside the inner layer, and an outer layer disposed outside the reinforcing layer, wherein the reinforcing layer comprises at least one layer made of organic fibers, and the inner layer comprises a polyamide elastomer comprising a hard segment made of polyamide 11 and a soft segment made of polyether. [2] The hydrogen filling hose according to [1], characterized in that, in the stress-strain curve obtained by a tensile test of the polyamide elastomer at a temperature of 23°C and a tensile speed of 100 mm / min, no lower yield point is observed, or the difference between the upper yield point stress and the lower yield point stress is 2 MPa or less. [3] A hydrogen filling hose according to [1] or [2], characterized in that the polyamide elastomer has a Type D durometer hardness of 50 to 74 at a temperature of 23°C. [4] The hydrogen filling hose according to [1] or [2], characterized in that the reinforcing layer includes at least one layer made of steel wire. [5] A hydrogen filling hose according to [1] or [2], characterized in that the rate of change in the outer diameter of the hose when the hose is pressurized at 70 MPa is 0.2 to 6%. [6] A hydrogen filling hose according to [1] or [2], characterized in that the rate of change in the inner diameter of the hose when the hose is pressurized at 70 MPa is 5 to 12%. [7] A hydrogen filling hose according to [1] or [2], characterized in that the bending rigidity of the hose at a bending radius of 180 mm is 5 to 23 N. [8] When a 13 mm diameter, 2 mm thick disc-shaped polyamide elastomer specimen was exposed to a hydrogen atmosphere at 90 MPa at 30°C for 24 hours, the amount of hydrogen dissolved Hw (mass ppm) and the oxygen permeability coefficient OPC (mm·cc / (m) at 21°C were determined. 2 A hydrogen filling hose according to [1] or [2], characterized in that the product of (day) * mmHg) * Hw * OPC is 15 to 55. [9] A hydrogen filling hose according to [1] or [2], characterized in that the polyamide elastomer does not rupture in a notched Izod impact test at a temperature of -40°C.

[10] A hydrogen filling hose according to [1] or [2], characterized in that the polyamide elastomer is subjected to repeated strain at a temperature of -35°C, an amplitude of 13.5%, and a frequency of 1.7Hz, with a fracture rate of 400,000 times or more.

[11] A hydrogen filling hose according to [1] or [2], characterized in that the plant-derived ratio of the polyamide elastomer is 50% or more. [Effects of the Invention]

[0008] The hydrogen filling hose of the present invention offers excellent hydrogen gas barrier properties, low-temperature durability, and ease of handling. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a partially broken perspective view of one embodiment of the hydrogen filling hose of the present invention. [Modes for carrying out the invention]

[0010] The present invention relates to a hydrogen filling hose comprising an inner layer, a reinforcing layer disposed outside the inner layer, and an outer layer disposed outside the reinforcing layer, wherein the reinforcing layer comprises at least one layer made of organic fibers, and the inner layer comprises a polyamide elastomer comprising a hard segment made of polyamide 11 and a soft segment made of polyether.

[0011] The hydrogen filling hose is a hose used to fill hydrogen from a tank, cylinder, etc. into other tanks, cylinders, etc., and preferably, it is a hose for filling hydrogen gas from a dispenser installed at a hydrogen station into a fuel cell vehicle or the like.

[0012] FIG. 1 is a perspective view of an embodiment of the hydrogen filling hose of the present invention, and is shown with a partial cutaway to clearly show the layer structure. However, the present invention is not limited to what is shown in the drawings. The hydrogen filling hose 1 includes an inner layer 2, a reinforcing layer 3, and an outer layer 4. The reinforcing layer 3 is disposed outside the inner layer 2. The outer layer 4 is disposed outside the reinforcing layer 3. The reinforcing layer 3 includes at least one layer 6 made of organic fiber. The reinforcing layer 3 of the hydrogen filling hose in FIG. 1 includes three layers 6 made of organic fiber and one layer 5 made of steel wire, but the reinforcing layer 3 of the hydrogen filling hose of the present invention may have one layer 6 made of organic fiber, and the layer 5 made of steel wire is not essential.

[0013] The inner layer contains a polyamide elastomer. A polyamide elastomer is also referred to as a polyamide-based thermoplastic elastomer. The polyamide elastomer includes a hard segment and a soft segment. The hard segment is made of polyamide 11. Polyamide 11 is a polymer of undecanolactam or 11-aminoundecanoic acid. The soft segment is made of polyether. The polyether is polyoxyalkylene, preferably polyoxyethylene or polyoxypropylene. The polyamide elastomer is commercially available, and commercial products can be used in the present invention. Examples of commercial products include PEBAX (registered trademark) manufactured by Arkema. Since the reinforcing layer includes a layer made of organic fiber, the hose becomes flexible and easy to handle, but the deformation of the inner layer becomes large. Therefore, by using a polyamide elastomer for the inner layer, the hydrogen gas barrier property and low-temperature durability can be improved.

[0014] In the stress-strain curve obtained from a tensile test at a temperature of 23°C and a tensile speed of 100 mm / min, it is preferable that no lower yield point is observed in the polyamide elastomer, or the difference between the upper yield point stress and the lower yield point stress is 2 MPa or less. The difference between the upper yield point stress and the lower yield point stress is more preferably 1.5 MPa or less, and even more preferably 1.0 MPa or less. The upper yield point stress refers to the stress at the upper yield point, and the lower yield point stress refers to the stress at the lower yield point. In a hose having an organic fiber in the reinforcing layer, since the deformation is large, when the inner layer is composed of a material having an upper and lower yield point, stress concentration easily occurs and fracture initiation points are likely to occur. Therefore, it is preferable that the inner layer is composed of a material in which no lower yield point is observed, or the difference between the upper yield point stress and the lower yield point stress is small.

[0015] The type D durometer hardness of the polyamide elastomer at 23°C is preferably 50 to 74, more preferably 55 to 73, and even more preferably 58 to 72. If the type D durometer hardness is too low, the degree of diameter reduction of the inner layer becomes large during the braiding of the reinforcing layer, making it difficult to manufacture. If the type D durometer hardness is too high, it is closer to the behavior of a polyamide resin rather than an elastomer, and the low-temperature durability deteriorates.

[0016] When the hydrogen dissolution amount Hw (mass ppm) when a disk-shaped test piece of the polyamide elastomer with a diameter of 13 mm and a thickness of 2 mm is exposed to a hydrogen atmosphere of 90 MPa at 30°C for 24 hours and the oxygen permeability coefficient OPC (mm·cc / (m 2 ·day·mmHg)) product Hw×OPC is preferably 15 to 55, more preferably 17 to 52, and even more preferably 20 to 50. When Hw×OPC is within the above numerical range, the damage to the inner layer by hydrogen is small, which is preferable.

[0017] It is preferable that the polyamide elastomer does not break in the notched Izod impact test at -40°C. That is, it is preferable that the polyamide elastomer has excellent impact resistance at low temperatures.

[0018] It is preferable that the polyamide elastomer has a fracture rate of 400,000 cycles or more when subjected to repeated strain at a temperature of -35°C, an amplitude of 13.5%, and a frequency of 1.7 Hz. In other words, it is preferable that the polyamide elastomer has excellent fatigue resistance at low temperatures.

[0019] The plant-derived content of the polyamide elastomer is preferably 50% or more, more preferably 55-98%, and even more preferably 60-96%. The plant-derived content refers to the proportion of plant-derived carbon among the carbon constituting the polyamide elastomer. By keeping the plant-derived content within the above numerical range, it is possible to reduce the environmental impact while obtaining the desired physical properties.

[0020] The inner layer may contain components other than polyamide elastomer, as long as they do not hinder the effects of the present invention.

[0021] The thickness of the inner layer is preferably 0.2 to 2.0 mm, more preferably 0.3 to 1.8 mm, and even more preferably 0.4 to 1.6 mm. If the inner layer is too thin, melt extrusion may become difficult or the extrusion method may be limited, and if it is too thick, the hose may lack flexibility and become difficult to handle.

[0022] The reinforcing layer is a layer provided between the inner and outer layers, and usually consists of a braided or spiral layer formed by braiding chemical fibers or metal wires. Examples of chemical fibers include poly(p-phenylenebenzbisoxazole) fibers, aramid fibers, and carbon fibers, but PBO fibers are preferred. The diameter of the chemical fibers is preferably 0.25 to 0.30 mm. Examples of metal wires include steel wire, copper and copper alloy wire, aluminum and aluminum alloy wire, magnesium alloy wire, titanium and titanium alloy wire, but steel wire is preferred. The diameter of the metal wire is preferably 0.25 to 0.40 mm.

[0023] In the present invention, the reinforcing layer includes at least one layer made of organic fibers. Including at least one layer made of organic fibers results in a flexible and easy-to-handle hose. Multiple layers made of organic fibers may be provided, and preferably, the reinforcing layer includes three layers made of organic fibers. The organic fibers are preferably PBO fibers. Preferably, the reinforcing layer further includes at least one layer made of steel wire. Since deformation would be too great if only layers made of organic fibers were present, it is preferable to include layers made of steel wire as well. When the reinforcing layer includes both layers made of organic fibers and layers made of steel wire, the layers made of steel wire are provided on the outside of the layers made of organic fibers. Providing the layers made of steel wire on the outside of the layers made of organic fibers makes it easier to ensure the flexibility and durability of the hose. It is more preferable that the reinforcing layer has a four-layer structure, including three layers made of organic fibers and one layer made of steel wire on the outside.

[0024] The hydrogen refueling hose includes an outer layer. The materials constituting the outer layer are not limited to thermoplastic elastomers and vulcanized rubber, but thermoplastic elastomers are preferred. The thermoplastic elastomers are not limited to polyester elastomers, but polyester elastomers, polyamide elastomers, and polyurethane elastomers are preferred.

[0025] Polyester elastomers (TPEEs) are thermoplastic elastomers in which the hard segment is polyester (e.g., polybutylene terephthalate) and the soft segment is polyether (e.g., polytetramethylene glycol) or polyester (e.g., aliphatic polyester). Polyester elastomers are commercially available, and commercially available products can be used in the present invention. Examples of commercially available polyester elastomers include "Perprene" (registered trademark) manufactured by Toyobo Co., Ltd. and "Hytrel" (registered trademark) manufactured by Toray DuPont Ltd.

[0026] Polyamide elastomers (TPAs) are thermoplastic elastomers in which the hard segment is polyamide (e.g., polyamide 6, polyamide 66, polyamide 11, polyamide 12) and the soft segment is polyether (e.g., polyethylene glycol, polypropylene glycol). Polyamide elastomers are commercially available, and commercially available products can be used in the present invention. Examples of commercially available polyamide elastomers include the "UBESTA" (registered trademark) XPA series from Ube Industries, Ltd. and "PEBAX" (registered trademark) from Arkema.

[0027] Polyurethane elastomers are block copolymers consisting of hard segments having urethane bonds and soft segments such as polyether, polyester, and polycarbonate. Polyurethane elastomers are commercially available, and commercially available products can be used in the present invention. Examples of commercially available polyurethane elastomers include "Elastran" (registered trademark) from BASF, "Milactran" (registered trademark) from Nippon Miractran, and "Rezamin" (registered trademark) from Dainichi Seika Kogyo.

[0028] The thickness of the outer layer is preferably 0.2 to 1.2 mm, more preferably 0.3 to 1.0 mm, and even more preferably 0.4 to 0.8 mm. If the outer layer is too thin, it may be easily damaged by friction, deformation, and impact when handling the hose, and the reinforcing layer may not be adequately protected. If it is too thick, the weight of the hose will increase, making it difficult to handle.

[0029] When the hose is pressurized at 70 MPa, the rate of change in the outer diameter of the hose is preferably 0.2 to 6%, more preferably 0.4 to 5.5%, and even more preferably 0.6 to 5.0%. Having the rate of change in outer diameter within the above range results in a hose with excellent durability, flexibility, and ease of handling.

[0030] When the hose is pressurized at 70 MPa, the rate of change in the inner diameter of the hose is preferably 5 to 12%, more preferably 5.5 to 11.5%, and even more preferably 6.0 to 11.0%. Having the rate of change in the inner diameter within the above range results in a hose with excellent durability, flexibility, and ease of handling.

[0031] The bending stiffness of the hose at a bending radius of 180 mm is preferably 5 to 23 N, more preferably 7 to 21 N, and even more preferably 9 to 20 N. Having the bending stiffness within this range makes it easier to achieve both pressure resistance and ease of handling for the hose.

[0032] The method for manufacturing a hydrogen refueling hose is not particularly limited, but it can be manufactured as follows: First, the inner layer (inner tube) is extruded into a tubular shape by extrusion molding, then fibers that will form a reinforcing layer are braided onto the tube, and finally, the outer layer (outer tube) is covered onto the fibers by extrusion molding. [Examples]

[0033] [raw materials] The raw materials used in the following examples and comparative examples are as follows: (Material for the inner layer) PA11-based TPAE-1: Arkema's polyamide elastomer (hard segment: polyamide 11, soft segment: polyether) "PEBAX" (registered trademark) 70R53SP01 (plant-derived ratio: 89%) PA11-based TPAE-2: Arkema's polyamide elastomer (hard segment: polyamide 11, soft segment: polyether) "PEBAX" (registered trademark) 63R53SP01 (plant-derived ratio: 79%) PA11-based TPAE-3: Arkema's polyamide elastomer (hard segment: polyamide 11, soft segment: polyether) "PEBAX" (registered trademark) 55R53SP01 (plant-derived ratio: 65%) PA12-based TPAE: Polyamide elastomer manufactured by Ube Industries, Ltd. (hard segment: polyamide 12, soft segment: polyether) "UBESTA" (registered trademark) "XPA" (registered trademark) 9063X1 PA11: Arkema Polyamide 11 "RILSAN" (registered trademark) BESN OTL (Materials for reinforcing layers) PBO fiber: Poly(p-phenylene benzbisoxazole) fiber with a diameter of 0.28 mm. Steel wire: Steel wire with a diameter of 0.35 mm (Material for outer layer) TPC: Toray DuPont Co., Ltd.'s thermoplastic polyester elastomer "Hytrel" (registered trademark) 4057N

[0034] [Examples 1-4 and Comparative Examples 1-3] After braiding the reinforcing layer, the inner layer material described in Table 1 was extruded into a 1 mm thick tube with an inner diameter that anticipated the reduction in diameter so that the inner diameter would be 8 mm. This tube was used as the inner layer, and the reinforcing layer described in Table 1 was braided on the outside of the inner layer. Furthermore, a thermoplastic polyester elastomer "Hytrel" (registered trademark) 4057N manufactured by Toray DuPont Co., Ltd. was extruded to a thickness of 0.7 mm on the outside of the reinforcing layer to form the outer layer, and a hose was manufactured. In Table 1, 3YB / 1WB means a layer configuration consisting of three layers of PBO fibers and one layer of steel wire provided on the outside, 4YB means a layer configuration consisting of four layers of PBO fibers, and 4WB means a layer configuration consisting of four layers of steel wire. The fabricated hoses were evaluated for their outer diameter change rate, inner diameter change rate, bending stiffness, diameter reduction during manufacturing, handling, hydrogen permeability, and low-temperature durability. The evaluation results are shown in Table 1.

[0035] The measurement and evaluation methods for the inner layer materials and hose measurement and evaluation items are as follows:

[0036] [Presence or absence of a lower yield point or the difference between the upper yield point and the lower yield point based on tensile testing of the inner layer material] The inner layer material was formed into a sheet with an average thickness of 1.0 mm using a 40 mmφ single-screw extruder with a 200 mm wide T-type die (manufactured by Plagiken Co., Ltd.), with the cylinder and die temperatures set to 210°C, the cooling roll temperature at 50°C, and the take-up speed at 2 m / min. This sheet was punched into a JIS No. 3 dumbbell shape, and a tensile test was performed at a temperature of 23°C and a tensile speed of 100 mm / min. The presence or absence of a lower yield point was determined from the stress-strain curve, or the difference between the upper yield point stress and the lower yield point stress was calculated. In Table 1, the column for "Presence or absence of lower yield point or difference between upper and lower yield point stresses by tensile test" indicates "None" if no lower yield point was observed, the difference between upper and lower yield point stresses is displayed if the difference is 2 MPa or less, and "Present" is displayed if the difference exceeds 2 MPa.

[0037] [Measuring hardness using a Type D durometer] The inner layer material was formed into a sheet with an average thickness of 2 mm using a 40 mmφ single-screw extruder with a 200 mm wide T-type die (manufactured by Plastic Technology Co., Ltd.), with the cylinder and die temperatures set to 210°C, the cooling roll temperature at 50°C, and the take-up speed at 2 m / min. This sheet was cut to the specified size, and three sheets were stacked to create a sample with a thickness of 6 mm. The hardness of this sample was measured by pressing an indenter against the sample for less than 1 second, in accordance with JIS K7215 "Durometer Hardness Test Method for Plastics".

[0038] [Measurement of hydrogen dissolution] The inner layer material was formed into a sheet with an average thickness of 2.0 mm using a 40 mmφ single-screw extruder with a 200 mm wide T-type die (manufactured by Plastic Technology Co., Ltd.), with the cylinder and die temperatures set to 210°C, the cooling roll temperature at 50°C, and the take-up speed at 1 m / min. This sheet was cut into a 13 mm diameter disc shape to prepare disc-shaped test specimens. The disc-shaped test specimens were placed in a pressure vessel and exposed to hydrogen at 30°C and 90 MPa for 24 hours. Immediately after reducing the pressure to atmospheric pressure, the disc-shaped test specimens were placed in a tube filled with nitrogen at 30°C. The gas inside the tube was introduced into a gas chromatograph from the end of the tube at regular intervals, and the hydrogen leaching out from inside the disc-shaped test specimen was detected. Measurement continued until no more hydrogen was detected, and the amount of hydrogen detected was accumulated to determine the amount of hydrogen dissolved in the disc-shaped test specimen due to the exposure, which was defined as the hydrogen solubility (Hw) (unit: mass ppm).

[0039] [Measurement of oxygen permeability coefficient] The inner layer material was formed into a sheet with an average thickness of 0.25 mm using a 40 mmφ single-screw extruder with a 200 mm wide T-type die (manufactured by Plastic Technology Co., Ltd.), with the cylinder and die temperatures set to 220°C, the cooling roll temperature at 50°C, and the take-up speed at 8 m / min. This sheet was cut to the specified size, and the oxygen permeability was measured using a MOCON OXTRAN1 / 50 at a temperature of 21°C and relative humidity of 0%, and the oxygen permeability coefficient (OPC) (unit: mm·cc / (m)) was determined. 2 We calculated the (day / mmHg) value.

[0040] [Low-temperature Izod impact test] The inner layer material was formed into a sheet with an average thickness of 3.0 mm using a 40 mmφ single-screw extruder with a 200 mm wide T-type die (manufactured by Plastic Technology Co., Ltd.), with the cylinder and die temperatures set to 210°C, the cooling roll temperature at 50°C, and the take-up speed at 0.75 m / min. From this sheet, strips measuring 63.5 mm in length and 12.7 mm in width were cut, notched, and subjected to an Izod impact test at -40°C in accordance with ASTM D256. In this test, if the sample broke, it was labeled "broken," and if the sample did not break, it was labeled "NB."

[0041] [Low-temperature fatigue resistance test] The inner layer material was formed into a sheet with an average thickness of 1.0 mm using a 40 mmφ single-screw extruder with a 200 mm wide T-type die (manufactured by Plastic Technology Co., Ltd.), with the cylinder and die temperatures set to 210°C, the cooling roll temperature at 50°C, and the take-up speed at 2 m / min. Twenty strips, 5 mm wide and 200 mm long, were cut from this sheet and subjected to repeated tensile deformation using a constant strain constant load fatigue testing machine manufactured by Ueshima Manufacturing Co., Ltd., under the conditions of a temperature of -35°C, a strain of 13.5%, and a speed of 100 rpm. The number of times in which 12 out of the 20 strips (60%) fractured was defined as the number of fracture cycles. Strips with fewer than 400,000 fracture cycles were labeled "Failed," and those with 400,000 or more fracture cycles were labeled "NB."

[0042] [Measurement of the rate of change in the outer diameter of the hose] The hose was cut to a specified length, and the percentage change in outer diameter when pressurized to 70 MPa at room temperature was measured in accordance with JIS K6330-2 "Test methods for rubber and plastic hoses - Part 2: Pressure resistance of hoses and hose assemblies".

[0043] [Measurement of the rate of change in the inner diameter of a hose] By cutting the hose to a predetermined length and measuring the internal volume V and length L under no load at room temperature and under pressure of 70 MPa, we can determine that V = π(D / 2). 2 The inner diameter D was determined using L, and the percentage change in inner diameter was calculated using the following formula. Inner diameter change rate (%) = (D1 - D0) / D0 × 100 However, D0 is the inner diameter under no load, and D1 is the inner diameter when pressurized to 70 MPa.

[0044] [Measurement of hose bending rigidity] The hose was cut to a specified length, and the bending stiffness (in N) at a bending radius of 180 mm at 25°C was measured in accordance with JIS K6330-9 "Test methods for rubber and plastic hoses - Part 9: Bending properties of hoses and pipes". A bending stiffness of 23 N or less indicates excellent performance.

[0045] [Diameter reduction during hose manufacturing] The inner layer material was extruded into a tube with an inner diameter of 8 mm and a thickness of 1 mm. This was used as the inner layer, and after braiding the reinforcing layers described in Table 1, the inner diameter was measured, and the diameter reduction ratio was calculated using the following formula. Diameter reduction ratio = (Inner diameter before braiding - Inner diameter after braiding) / Inner diameter before braiding During hose manufacturing, the diameter reduction was categorized as follows: "Small" for a reduction rate of less than 5%, "Medium" for a reduction rate of 5% or more but less than 12%, and "Large" for a reduction rate of 12% or more. A smaller diameter reduction is better.

[0046] [Evaluation of hose handling] In the above [measurement of hose bending rigidity], hoses with a bending rigidity exceeding 23N at a bending radius of 180mm were judged as "poor" because they were too rigid and difficult to handle, while those with a bending rigidity of 23N or less were judged as "good" because they were flexible and easy to handle.

[0047] [Measuring hydrogen permeability through a hose] A hose was cut to a length of 300 mm, and a hydrogen permeation test was conducted using a GTR-100HAYG isobaric hose permeability measuring device manufactured by GTR Tech Co., Ltd. at a pressure of 2 MPa and a temperature of 60°C to compare the magnitude of hydrogen permeation. The hydrogen permeation amount of Comparative Example 2 was organized using an index with the index of 100, and an index of 95 or higher was indicated as "high," an index of 80 or higher but less than 95 as "medium," and an index of less than 80 as "low." A lower hydrogen permeation amount is preferable.

[0048] [Evaluation of low-temperature durability of hoses] In accordance with JIS K6330-8 "Test methods for rubber and resin hoses - Part 8: Impact pressure test", fluid was circulated through a hose fixed in a U-shape, and an impact waveform pressure of 90 MPa with an ambient temperature of -40°C, a frequency of 1 Hz, and a maximum pressure was applied 100,000 times or until the hose broke. After completion, hoses without damage to the inner layer were marked "Good", those with cracks on the inner layer surface but no leakage were marked "Acceptable", and those that leaked fluid before 100,000 cycles were marked "Unacceptable".

[0049] [Table 1]

[0050] This disclosure encompasses the following inventions: Invention [1] A hydrogen filling hose comprising an inner layer, a reinforcing layer disposed on the outside of the inner layer, and an outer layer disposed on the outside of the reinforcing layer, wherein the reinforcing layer comprises at least one layer made of organic fibers, and the inner layer comprises a polyamide elastomer comprising a hard segment made of polyamide 11 and a soft segment made of polyether. Invention [2] A hydrogen filling hose according to Invention [1], characterized in that, in the stress-strain curve obtained by a tensile test of a polyamide elastomer at a temperature of 23°C and a tensile speed of 100 mm / min, no lower yield point is observed, or the difference between the upper yield point stress and the lower yield point stress is 2 MPa or less. Invention [3] A hydrogen filling hose according to Invention [1] or [2], characterized in that the polyamide elastomer has a Type D durometer hardness of 50 to 74 at a temperature of 23°C. Invention [4] A hydrogen filling hose according to any one of Inventions [1] to [3], characterized in that the reinforcing layer includes at least one layer made of steel wire. Invention [5] A hydrogen filling hose according to any one of Inventions [1] to [4], characterized in that the rate of change of the outer diameter of the hose when the hose is pressurized at 70 MPa is 0.2 to 6%. Invention [6] A hydrogen filling hose according to any one of Inventions [1] to [5], characterized in that the rate of change of the inner diameter of the hose when the hose is pressurized at 70 MPa is 5 to 12%. Invention [7] A hydrogen filling hose according to any one of Inventions [1] to [6], characterized in that the bending rigidity force of the hose at a bending radius of 180 mm is 5 to 23 N. Invention [8] Hydrogen dissolution amount Hw (mass ppm) and oxygen permeability coefficient OPC (mm·cc / (m) at 21°C when a disc-shaped test specimen of polyamide elastomer with a diameter of 13 mm and a thickness of 2 mm is exposed to a hydrogen atmosphere of 90 MPa at 30°C for 24 hours. 2 A hydrogen filling hose according to any one of the inventions [1] to [7], characterized in that the product of (day) mmHg) Hw × OPC is 15 to 55. Invention [9] A hydrogen filling hose according to any one of Inventions [1] to [8], characterized in that the polyamide elastomer does not rupture in a notched Izod impact test at a temperature of -40°C. Invention

[10] A hydrogen filling hose according to any one of Inventions [1] to [9], characterized in that the polyamide elastomer is subjected to repeated strain at a temperature of -35°C, an amplitude of 13.5%, and a frequency of 1.7Hz, with a fracture count of 400,000 or more cycles. Invention

[11] A hydrogen filling hose according to any one of Inventions [1] to

[10] , characterized in that the plant-derived ratio of the polyamide elastomer is 50% or more. [Industrial applicability]

[0051] The hydrogen refueling hose of the present invention can be suitably used as a hose for refueling fuel cell vehicles and the like from a dispenser installed at a hydrogen station. [Explanation of Symbols]

[0052] 1. Hydrogen refueling hose 2. Inner layer 3. Reinforcement layer 4 Outer layer 5 layers made of steel wires 6. Layer made of organic fibers

Claims

1. A hydrogen filling hose comprising an inner layer, a reinforcing layer disposed outside the inner layer, and an outer layer disposed outside the reinforcing layer, wherein the reinforcing layer comprises at least one layer made of organic fibers, and the inner layer comprises a polyamide elastomer comprising a hard segment made of polyamide 11 and a soft segment made of polyether.

2. The hydrogen filling hose according to claim 1, characterized in that, in the stress-strain curve obtained by a tensile test of the polyamide elastomer at a temperature of 23°C and a tensile speed of 100 mm / min, no lower yield point is observed, or the difference between the upper yield point stress and the lower yield point stress is 2 MPa or less.

3. The hydrogen filling hose according to claim 1 or 2, characterized in that the polyamide elastomer has a Type D durometer hardness of 50 to 74 at a temperature of 23°C.

4. The hydrogen filling hose according to claim 1 or 2, characterized in that the reinforcing layer includes at least one layer made of steel wire.

5. A hydrogen filling hose according to claim 1 or 2, characterized in that the rate of change in the outer diameter of the hose when the hose is pressurized at 70 MPa is 0.2 to 6%.

6. A hydrogen filling hose according to claim 1 or 2, characterized in that the rate of change in the inner diameter of the hose when the hose is pressurized at 70 MPa is 5 to 12%.

7. The hydrogen filling hose according to claim 1 or 2, characterized in that the bending rigidity force at a bending radius of 180 mm is 5 to 23 N.

8. The amount of hydrogen dissolved in a 13 mm diameter, 2 mm thick disc-shaped polyamide elastomer specimen was exposed to a 90 MPa hydrogen atmosphere at 30°C for 24 hours. The hydrogen dissolution rate Hw (mass ppm) and the oxygen permeability coefficient OPC (mm·cc / (m)) at 21°C were determined. ２ A hydrogen filling hose according to claim 1 or 2, characterized in that the product of (day / mmHg) Hw × OPC is 15 to 55.

9. The hydrogen filling hose according to claim 1 or 2, characterized in that the polyamide elastomer does not rupture in a notched Izod impact test at a temperature of -40°C.

10. The hydrogen filling hose according to claim 1 or 2, characterized in that the polyamide elastomer has a fracture rate of 400,000 or more cycles when subjected to repeated strain at a temperature of -35°C, an amplitude of 13.5%, and a frequency of 1.7 Hz.

11. A hydrogen filling hose according to claim 1 or 2, characterized in that the plant-derived ratio of the polyamide elastomer is 50% or more.

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