HIGH-PRESSURE HOSES FOR DELIVERING HYDROGEN

Description

[0001] The present invention relates to a high-pressure hose with a pressure classification of H70 according to DIN ISO 19880-5 and / or a burst pressure of at least 3500 bar, wherein the hose has a layered structure with a barrier layer made of polyketone, at least one reinforcement layer, and an outer layer made of a polymeric material. The present invention relates to a method for producing such hoses, tank filling devices equipped with such hoses, and uses of corresponding high-pressure hoses for transferring hydrogen from a storage container to a tank. State of the art

[0002] In recent years, the development of fuel cell vehicles has experienced a significant boost. However, hydrogen as a fuel places considerable demands on the materials used to store and transport the hydrogen, due to the small molecular size of hydrogen. One aspect of this is the development of hoses through which a fuel cell vehicle and the like can be filled with hydrogen gas from a filling pump installed in a hydrogen station. In order to increase the range of a fuel cell vehicle, a fuel tank must be filled with hydrogen gas under high pressure. Therefore, the hoses used for filling with hydrogen must be able to withstand high internal pressures of, for example, 70 MPa or more over a relatively wide temperature range (-40°C to around 85°C on the vehicle side).

[0003] Materials for the inner layer of such hoses must meet a number of requirements, including, in particular, low hydrogen permeability, a certain degree of flexibility to allow the hose to be connected to the vehicle by a user, and, of course, sufficient strength properties. Barrier materials described so far for an inner hose layer include nylon (e.g., in the form of nylon 6, nylon 66, or nylon 11), polyacetal, ethylene-vinyl alcohol copolymer, or NBR (nitrile butadiene rubber).

[0004] For example, EP 3 627 026 A1 describes hydrogen fuel hoses with an inner and outer layer and three or more reinforcement layers, each having a precisely specified braid angle of 53.5 to 55.5°. In one embodiment of EP 3 627 026 A1, the inner layer is made of nylon and the outer layer is made of polyester.

[0005] JP 2017-106553 A describes hydrogen hoses with high burst resistance, which, in addition to inner and outer layers, have reinforcement layers made of polyparaphenylene benzbisoxazole fibers, with which a service pressure of 70 MPa can be achieved.

[0006] Elaflex markets a hydrogen hose for mobility applications that features an inner NBR layer modified to provide electrical conductivity, several layers of low-stretch textile braid, and an outer layer of chloroprene rubber (see diagram). https: / / elaflex.de / documents / download / ElaflexInformation / ELAFLEX Information 1.20.pdf ).

[0007] Furthermore, hoses for high-pressure applications in the context of oil and gas production have been described, which are subject to significant pressure differences and tensile forces when used below the water surface. For example, US 2001 / 021426 A1 discloses unbonded hoses with a liquid-impermeable barrier layer, reinforcement layers, and an outer layer. These hoses feature a flexible metal cylinder as the innermost layer, intended to provide the required mechanical strength and flexibility. The hoses are accordingly designed for applications where high external pressures act on the hose.

[0008] Since the barrier layer material in hoses used to conduct hydrogen at high pressure must meet various requirements, the problem arises of providing materials that exhibit the most favorable overall property profile possible. For example, ethylene-vinyl alcohol copolymers, although they exhibit very low permeability to hydrogen gas, do not have satisfactory mechanical and strength properties (e.g., tensile strength, elongation at break, or notched impact strength). Polyamides such as nylon 6 or nylon 11 do have favorable elongation at break or notched impact strength properties, but the tensile strength of these materials is comparatively low, and their permeability to hydrogen gas is also unsatisfactory.Other materials such as PEEK (= polyetheretherketone) have very favorable mechanical properties and in particular a very high tensile strength, but can only be processed at very high temperatures of more than 340°C and have unsatisfactory hydrogen permeability.

[0009] Given this state of the art, there is a need for a barrier material that exhibits the lowest possible permeability to hydrogen while simultaneously offering favorable flexibility and mechanical properties and allowing processing at lower temperatures than, for example, PEEK. Furthermore, such a material should, if possible, allow the incorporation of additives to impart electrical conductivity without significantly impairing the material's mechanical and permeability properties.

[0010] The present invention addresses this need. Description of the invention

[0011] In the investigations underlying this invention, the inventors have surprisingly found that an aliphatic polyketone has a very favorable property profile with suitable flexibility and mechanical properties and low hydrogen permeability, and is also processable by extrusion and allows the inclusion of additives to impart electrical conductivity.

[0012] Accordingly, according to a first aspect, the present invention relates to a high-pressure hose with a pressure classification of H70 according to DIN ISO 19880-5 and / or a bursting pressure of at least 3500 bar, wherein the hose has a layer structure with an inner barrier layer, at least one reinforcement layer and an outer layer formed from a polymeric material, and wherein the barrier layer is formed from an aliphatic polyketone of the formula [[-CHR 1 CH 2 (C=O)-] n [-CHR 2 CH 2 (C=O)-] m ] p, wherein R 1 and R 2 are different from one another and independently of one another represent hydrogen or a C 1 -C 12 alkyl group, n+m=1, and p is an integer, and wherein the two comonomers are randomly distributed or are present as blocks.

[0013] With regard to the pressure classification "H70," it should be noted that DIN ISO 19880-5 specifies a number of requirements (e.g., regarding electrical conductivity) that do not necessarily have to be met in the invention. In the context of the invention described here, the reference to the pressure classification H70 is primarily to be understood as a reference to a minimum burst pressure that must be achieved by an H70 hose. Preferably, however, such a hose should also meet the operating pressure specification (HSL = Hydrogen Service Level) according to DIN ISO 19880-5 for an H70 hose, which is 700 bar.

[0014] In the specified aliphatic polyketone, when R 1 and / or R 2 represents a C 1 -C 12 alkyl group, the C 1 -C 12 alkyl group is preferably selected from methyl, ethyl, propyl, pentyl or heptyl.

[0015] In a particularly preferred embodiment, R 1 is a methyl group and R 2 is H.

[0016] When R 1 is a C 1 -C 12 alkyl group, "n" is preferably less than 0.5, especially less than 0.1, and most preferably between 0.02 and 0.08; for such values ​​of n, it is preferred that R 1 is a methyl group and R 2 is H. In another embodiment, n = 0 and R 2 is H, in which case the aliphatic polyketone is present as poly(ethylene ketone).

[0017] "p" is preferably an integer between 500 and 5000.

[0018] In one embodiment of the present invention, the aliphatic polyketone is semicrystalline. Partial crystallinity can be detected by DSC measurements of the polymer.

[0019] In a preferred embodiment of the present invention, the aliphatic polyketone polymer contains at least 80 vol.%, in particular at least 90 vol.%, and particularly preferably at least 95 vol.% of the structural units (I) and (II).

[0020] In a preferred embodiment of the present invention, the aliphatic polyketone has a melting temperature between 200°C and 250°C, preferably between 210°C and 240°C. Furthermore, it is preferred within the scope of the present invention if the aliphatic polyketone has a weight-average molecular weight M w of at least 40,000 g / mol, and in particular at least 60,000 g / mol. In a particularly preferred embodiment of the present invention, the aliphatic polyketone has a molecular weight of at least 200,000 g / mol.

[0021] In a preferred embodiment of the present invention, the aliphatic polyketone has a weight-average molecular weight M w of 140,000 g / mol to 410,000 g / mol, more preferably a weight-average molecular weight of 150,000 g / mol to 210,000 g / mol or of 290,000 g / mol to 400,000 g / mol, and most preferably a weight-average molecular weight of 160,000 g / mol to 200,000 g / mol or of 300,000 g / mol to 390,000 g / mol. The weight-average molecular weight M w is to be determined here by GPC using suitable standards (e.g., polystyrene).

[0022] A commercially available aliphatic polyketone that can be used for the production of the barrier layer of the high-pressure hoses according to the invention are the products marketed by Hyosung under the trade name POKETONE.

[0023] In a particularly preferred embodiment, the polyamide of the barrier layer has a total gas permeability for hydrogen (H 2 ) of 1750 cm 3 < / (m 2 < *d) or less (determined according to DIN 53880 (2006) at 30°C and 30 bar, 0% relative humidity)), in particular 1500 cm 3 < / (m 2 *d) or less and particularly preferably 1350 cm 3 < / (m 2 *d) or less.

[0024] The aliphatic polyketone can be processed, for example, by extrusion.

[0025] The aliphatic polyketone in the barrier layer may additionally contain one or more additives selected from one or more of antioxidants, heat stabilizers, ultraviolet absorbers, light stabilizers, lubricants, inorganic fillers, antistatic agents, flame retardants, crystallization accelerators, plasticizers, dyes, impact modifiers, and the like.

[0026] The barrier layer has a thickness adapted to achieve the desired gas permeability. The barrier layer preferably has a thickness of at least 0.2 mm and less than 2.0 mm, with a thickness in the range of 0.5 to 1.5 mm being preferred. The inner diameter of the barrier layer is preferably at least 6 mm and more preferably in the range of 7 mm to 12 mm.

[0027] To provide electrical conductivity, the barrier layer may contain an electrically conductive additive or filler.

[0028] Suitable electrically conductive additives or fillers are all fillers that can impart electrically conductive properties to the polyamide, e.g. particulate, flaky or fibrous fillers.

[0029] Examples of suitable particulate fillers are carbon black and graphite. Examples of flaky fillers that can be suitably used are aluminum flakes, nickel flakes, and nickel-coated mica. Examples of fibrous fillers include carbon fibers, carbon nanotubes, carbon-coated ceramic fibers, carbon whiskers, and metal fibers such as aluminum fibers, copper fibers, brass fibers, and stainless steel fibers. Of these, carbon black and a mixture of carbon black and carbon nanotubes are most preferred as electrically conducting fillers.

[0030] Carbon black that can be used in the present invention includes all carbon blacks generally used to impart electrical conductivity. Preferred examples of the carbon black include, but are not limited to, acetylene black obtained by the complete combustion of acetylene gas, Ketjen black produced by furnace-type incomplete combustion from crude oil, oil black, naphthalene black, thermal black, lamp black, channel black, roller black, and disc black. Of these, acetylene black and furnace black (Ketjen black) are more preferred.

[0031] Regarding carbon black, various carbon powders are produced, which differ in properties such as particle size, surface area, DBP absorption, and ash content. The carbon black that can be used in the present invention is not particularly limited in these properties, but those having a good chain structure and a large aggregation density are preferred. From the viewpoint of impact resistance, the carbon black is preferably not blended in a large amount. In order to obtain excellent electrical conductivity with a smaller amount, the average particle size of carbon black is preferably 500 nm or less, more preferably 5 to 100 nm, and even more preferably 10 to 70 nm. The surface area (by BET method) is preferably 10 m 2 / g or more, more preferably 300 m 2 / g or more, and even more preferably 500 to 1.500 m 2 / g, and the DBP (dibutyl phthalate) absorption is preferably 50 ml / 100 g or more, more preferably 100 ml / 100 g or more, and even more preferably 300 ml / 100 g or more. The ash content of carbon black is preferably 0.5% or less, and more preferably 0.3% or less. DBP absorption as used herein refers to a value measured according to the method prescribed in ASTM-D2414. A carbon black having a volatile content of less than 1.0 wt% is more preferred.

[0032] The electrically conductive filler may be surface-treated with a surface treatment agent, such as a titanate-, aluminum-, or silane-type surface treatment agent. Furthermore, the electrically conductive filler may be particulate to improve processability during melt-kneading with the aliphatic polyketone.

[0033] The amount of the electrically conductive filler mixed is variable depending on the type of filler and cannot be specified independently, but in view of the balance of electrical conductivity, melt flowability and mechanical strength, a proportion of electrically conductive filler of 3 to 30 parts by weight based on 100 parts by weight of aliphatic polyketone can be specified as favorable.

[0034] To achieve sufficiently high antistatic performance, the electrically conductive filler is preferably blended in an amount such that the molded article obtained by melt-extruding the polyketone composition containing the electrically conductive filler exhibits conductivity suitable for dissipating static charges. However, blending the electrically conductive filler easily leads to a reduction in mechanical strength and melt flowability, so the amount should be limited to the minimum required for the desired level of electrical conductivity.

[0035] The barrier layer made of the aliphatic polyketone generally forms the innermost layer of the high-pressure hose. However, in individual cases, another polymeric material can form the innermost layer, and the barrier layer made of the aliphatic polyketone can be arranged on top of it. In this case, the other material usually has a higher permeability to hydrogen than the barrier layer made of the aliphatic polyketone. Due to the negative influence of hydrogen on metal, and in particular steel, at high pressure, the innermost layer of the high-pressure hose according to the invention is not a metal layer, and in particular not a steel layer.

[0036] In addition, the high-pressure hose according to the invention can have further polymer layers between the inner barrier layer and reinforcement layers, between reinforcement layers or between the outermost reinforcement layer and the outer layer formed from a polymeric material.

[0037] In addition to the barrier layer made of aliphatic polyketone, the high-pressure hose according to the invention additionally contains at least one reinforcement layer, with multiple reinforcement layers, e.g., two, three, four, five, or six reinforcement layers, being preferred. For preferred embodiments of reinforcement layers and their arrangements, reference can be made to the corresponding statements in this regard, for example, in EP 3 627 026 A1.

[0038] In one embodiment, one or more reinforcement layers are formed from a woven, knitted, or braided fiber material, wherein the fibers are sufficiently stable and have a strength suitable for absorbing high internal pressures. Preference is given to fibers with a tensile strength, determined according to DIN EN ISO 2062 (2010), of at least 2 GPa. The fibers can be formed from an organic polymer, e.g., polyamide, polyester, or polyethylene with a higher molecular weight, e.g., more than 3,000,000 (UHMWPE). In one embodiment, the fibers are based on polyparaphenylenebenzobisoxazole or UHMWPE. The reinforcement(s) can advantageously also be formed as a cord or tape made of the aforementioned materials with a unidirectional orientation, particularly if the reinforcement is formed from UHMWPE.

[0039] Alternatively or additionally, one or more reinforcement layers may be formed from metal wire or metal strip, wherein in particular metal wires and strips made of steel, copper or copper alloy (according to JIS H 3260), aluminum or aluminum alloy (according to JIS H 4040), magnesium alloy (according to JIS H 4203), titanium or titanium alloy (according to JIS H 4670) may be used.

[0040] The polymeric material forming the outer layer of the high-pressure hose according to the invention is not subject to any relevant restrictions, provided that the material should be sufficiently flexible and stable above the hose's operating temperature. Preferred polymeric materials include, for example, rubbers such as chloroprene rubber, chloroprene acrylate rubber, butyl rubber, ethylene-propylene rubber, chlorosulfonated polyethylene rubber, or thermoplastic polyurethane elastomers and thermoplastic materials such as polyurethane, polyamide, e.g., polyamide 12, or polyester.

[0041] The outer layer advantageously has a thickness in the range of at least 0.2 mm and 1.5 mm or less, with a thickness in the range of at least 0.5 mm and 1.0 mm or less being preferred. The outer diameter of the outer layer is not subject to any relevant restrictions, but will usually be at least 12 mm and 18 mm or less.

[0042] The outer layer can be continuous. Alternatively, the outer layer can have perforations through which gases, particularly hydrogen, penetrating from the inside to the outside of the hose can escape, preventing the formation of bubbles or delamination.

[0043] In one embodiment, one or more layers of the hose are "connected," meaning that the connection prevents the layers from sliding against each other in the longitudinal direction of the hose. In a hose according to the invention, for example, the barrier layer can be connected to adjacent reinforcement layers, or the outermost reinforcement layer can be connected to the outer layer formed from a polymeric material. Furthermore, all layers in the hose (with the exception of the reinforcement layers, if appropriate) can be connected to each other.

[0044] In a further aspect, the present invention relates to a method for producing a high-pressure hose as described above, which comprises the following steps: Applying a layer of aliphatic polyketone to a mandrel or mandrelless to form a polyketone tube; applying one or more reinforcement layers to the polyketone tube; applying an outer layer of a polymeric material to the one or more reinforcement layers.

[0045] The application of the aliphatic polyketone onto the mandrel or mandrelless is usually carried out from the melt, e.g. by extrusion.

[0046] In a further aspect, the present invention relates to a tank filling device comprising a high-pressure hose as described above. In addition to the hose, the tank filling device expediently comprises a dispensing device for fuel conducted through the device and a closure device for connecting the dispensing device in a pressure-tight manner to a container into which a fuel (i.e. in particular hydrogen) is to be introduced. In a further aspect, the present invention relates to the use of a high-pressure hose as described above for transferring hydrogen from a storage container into a tank. The tank is particularly preferably the tank of an aircraft, ship, or vehicle, such as a passenger car, truck, or rail vehicle.

[0047] In a further aspect, the present invention relates to the use of an aliphatic polyketone of the formula [[-CHR 1 CH 2 (C=O)-] n [-CHR 2 CH 2 (C=O)-] m ] p where R 1 and R 2 are different from one another and independently of one another are hydrogen or a C 1 -C 12 alkyl group, n+m=1, and p is an integer, and where the two comonomers are randomly distributed or blocked, as a barrier layer material in a hose for transporting hydrogen with a density of at least 24 kg / m 3< and preferably in the range from 35 to 45 kg / m 3< .

[0048] For the above, embodiments or configurations described above as preferred or expedient for one aspect of the invention are also intended to be considered preferred or expedient for all other described aspects, even if they are not explicitly listed.

[0049] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. Examples Example 1: Comparison of the properties of different materials for the inner layer of a hydrogen high-pressure hose

[0050] The properties relevant for a high-pressure hose inner or barrier layer are compared with other materials in the following Table 1: Table 1 polymer Melting point [°C] Tensile strength [MPa] 1< Elongation at break [%] 1< Notched impact strength [kJ / m 2< ] 2< Gas permeability [cm 3 < / (m 2 < *d)] 3 < Polyketone 222 56 250 16 1342 PEEK 340 95 25 7 2900 PVDF 164 12 50 100 1508 POM-C 166 64 30 6,5 277,5 PA6 220 23 50 80 1820 PA11 181 26 50 100 2545 EVOH 190 35 24 12 3,62 FTPV 220 24 6043 1 = determined according to ISO 527; 2 = determined according to ISO 179 / 1eA; 3 = determined at 30°C, 30 bar, 0% relative humidity.

[0051] As can be seen from Table 1, the aliphatic polyketone is among the top three in the categories of tensile strength, impact strength, and gas permeability, while other materials fall significantly short in at least one of these categories. Across all parameters, the aliphatic polyketone thus demonstrates clear advantages. Furthermore, due to its melting temperature, the aliphatic polyketone enables easy processing and also provides sufficient temperature resistance, and it meets the (di)electrical property criteria according to ISO 19880-5 (Section 7.18.4: Criteria of electrical properties of lining material). Example 2: Production of a high-pressure hose according to the invention

[0052] An inner layer of polyketone was extruded onto a mandrel with a thickness of 0.5 mm. Four reinforcement layers with reinforcing strands of high-molecular-weight polyethylene were then applied to this layer. Finally, a layer of thermoplastic polyurethane with a thickness of 1.0 mm was applied to this construction as the outer layer.

[0053] A high-pressure hose with an analogous structure was manufactured by incorporating metal wires or an electrically conductive textile yarn into the reinforcement layers to avoid electrical charges in the reinforcement area of ​​the hose.

[0054] The hoses produced in this way were stable up to a pressure of 3500 bar and showed sufficient impermeability to hydrogen.

Claims

1. High-pressure hose having a pressure classification of H70 according to DIN ISO 19880-5 and / or a burst pressure of at least 3500 bar, wherein the hose has a layered structure comprising an inner barrier layer, at least one strength member layer and an outer layer formed from a polymeric material and wherein the inner barrier layer is formed from an aliphatic polyketone of formula         [[-CHR1CH2(C=O)-]n[-CHR2CH2(C=O)-]m]p, wherein R1 and R2 are different from one another and independently represent hydrogen or a C1-C12-alkyl group, n+m=1, and p is an integer and wherein the two comonomers are statistically distributed or present as blocks.

2. High-pressure hose according to Claim 1, wherein the barrier layer is in the form of an inner layer having a layer thickness of at least 0.2 mm and less than 2.0 mm and preferably in the range from 0.5 to 1.5 mm.

3. High-pressure hose according to Claim 1 or 2, wherein the barrier layer contains a filler which imparts electrical conductivity, preferably selected from one or more of carbon black, carbon fibres, carbon nanotubes, carbon-coated ceramic fibres, carbon whiskers and metal fibres, such as aluminium fibres, copper fibres, brass fibres and stainless steel fibres, preferably in the form of carbon black or a combination of carbon black and carbon nanotubes.

4. High-pressure hose of at least one of Claims 1 to 3, wherein the aliphatic polyketone of the barrier layer has a gas permeability for hydrogen (H2) of 1750 cm3 / (m2*d) or less (determined according to DIN 53880 (2006) at 30°C and 30 bar, 0% relative humidity), especially 1500 cm3 / (m2*d) or less and preferably 1350 cm3 / (m2*d) or less.

5. High-pressure hose according to at least one of the preceding claims, wherein the hose has at least one strength member layer formed from high-strength organic fibres, wherein the fibres have a tensile strength, determined according to DIN EN ISO 2062, of at least 2 GPa, wherein the organic fibres are preferably based on polyparaphenylene benzobiisoxazole.

6. High-pressure hose according to at least one of the preceding claims, wherein the hose has at least one strength member layer formed from metal wire, wherein the metal wire is preferably made of steel, copper or copper alloy (according to JIS H 3260), aluminium or aluminium alloy (according to JIS H 4040), magnesium alloy (according to JIS H 4203), titanium or titanium alloy (according to JIS H 4670).

7. High-pressure hose according to at least one of the preceding claims, wherein the outer layer of the hose formed from a polymeric material is formed from a rubber or a thermoplastic material, wherein the rubber or the thermoplastic material is preferably selected from chloroprene rubber, chloroprene acrylate rubber, butyl rubber, ethylene-propylene rubber, chlorosulfonated polyethylene rubber, polyurethane, polyamide and polyester.

8. High-pressure hose according to at least one of the preceding claims, wherein the outer layer formed from a polymeric material has perforations.

9. High-pressure hose according to at least one of the preceding claims, wherein the hose has an internal diameter of at least 6 mm and preferably 7 mm to 12 mm.

10. Process for producing a high-pressure hose according to at least one of the preceding claims, comprising: - applying a layer of aliphatic polyketone to a mandrel or without a mandrel to form a polyketone tube; - applying one or more strength member layers to the polyketone tube; - applying an outer layer of a polymeric material to the one or more strength member layers.

11. Tank filling apparatus comprising a high-pressure hose according to any of Claims 1 to 9.

12. Use of a high-pressure hose according to at least one of Claims 1 to 9 for transferring hydrogen from a storage vessel into a tank, preferably a tank of a vehicle or aircraft or ship.

13. Use of an aliphatic polyketone of formula         [[-CHR1CH2(C=O)-]n[-CHR2CH2(C=O)-]m]p, wherein R1 and R2 are different from one another and independently represent hydrogen or a C1-C12-alkyl group, n+m=1 and p is an integer and wherein the two comonomers are statistically distributed or blocked, as a barrier layer material in a hose for transporting hydrogen having a density of at least 24 kg / m3 and preferably in the range from 35 to 45 kg / m3.