High-pressure hose

Abstract

The invention relates to a high-pressure hose having: at least one inner layer (1); at least one four-sheet or multi-sheet reinforcing support layer (2); and a cover layer (3); the reinforcing support layer (2) being arranged between the inner layer (1) and the cover layer (3), the inner layer (1) having a first polymer mixture comprising a thermoplastic polymer with a degree of crystallinity of greater than or equal to 20%, and the cover layer (3) having a second polymer mixture, characterised in that the reinforcing support layer (2) has at least two sheets of a spirally arranged metal wire (2aa, 2bb) and at least two sheets of an elastomer mixture (2a, 2b), at least one sheet of the elastomer mixture (2b) being arranged between two sheets of the spirally arranged metal wire (2aa, 2bb). The hose according to the invention is particularly suitable for use in refuelling hydrogen vehicles or hydrogen aircrafts and the associated supply and logistics chain in particular due to its high flexibility at low temperatures, high pressure resistance and long service life.

Description

[0001] high-pressure hose

[0002] The invention relates to a high-pressure hose comprising at least one inner layer (1), a two- or multi-layer reinforcement layer (2), and a cover layer (3), wherein the reinforcement layer (2) is arranged between the inner layer (1) and the cover layer (3), wherein the inner layer (1) comprises a first polymer mixture comprising a thermoplastic polymer with a degree of crystallinity of greater than or equal to 20%, and wherein the cover layer (3) comprises a second polymer mixture. The invention also relates to the use of the high-pressure hose for refueling vehicles or aircraft with hydrogen.

[0003] In the specialist world, high-pressure hoses are hoses that have an operating pressure of at least 300 bar and up to 700 bar and more (e.g. 1000 bar). These are used, for example, in the refueling of hydrogen vehicles or hydrogen aircraft between the filling nozzle and the refueling unit. During refueling, the hydrogen is cooled to -40°C (minus forty degrees Celsius) and fed to the vehicle or aircraft at a maximum pressure of 875 bar. The burst pressure of the hose must be 5 times the operating pressure (5-fold safety factor). The high-pressure hoses currently available on the market for this application are not particularly flexible due to the pressure requirements. The dynamic stress applied immediately before, during, and after the refueling process, such as torsion, has a negative impact on their service life. The hoses are not robust enough to withstand a sufficiently high number of refueling processes.

[0004] WO 2022 / 135637 A1 discloses a high-pressure hose particularly suitable for refueling vehicles or aircraft with hydrogen. This hose has an inner layer that acts as a hydrogen barrier layer and is composed of a single-layer or multi-layer extruded polymer composition. This layer is followed by one or more reinforcement layers and a polymer outer layer. While the barrier effect against hydrogen is as high as possible, the hose still lacks the necessary flexibility, especially at low temperatures.

[0005] The object of the present invention is therefore, based on WO 2022 / 135637 A1, to provide a high-pressure hose which is characterized by flexibility with sufficiently high torsional resistance and service life and at the same time has a high barrier effect against technical gases, in particular hydrogen.

[0006] This object is achieved by a high-pressure hose having at least one inner layer, at least one four-layer or multi-layer strength-bearing layer and a cover layer, wherein the strength-bearing layer is arranged between the inner layer and the cover layer, wherein the inner layer has a first polymer mixture comprising a thermoplastic polymer with a degree of crystallinity of greater than or equal to 20% and wherein the cover layer has a second polymer mixture, characterized in that the strength-bearing layer has at least two layers of a spirally arranged metal wire and at least two layers of an elastomer mixture, wherein at least one layer of the elastomer mixture is arranged between two layers of the spirally arranged metal wire.

[0007] The reinforcement layer is constructed of at least four or more layers. At least two of the four layers of the reinforcement layer of the high-pressure hose according to the invention are made of metal wires, which are used to increase the strength of the construction. By pre-bending the reinforcements during spiraling of the metal wires, the bending resistance is greatly reduced, thus increasing the flexibility of the high-pressure hose. The metal is preferably a high-strength steel or stainless steel alloy, which can optionally be adhesion-activated by a surface coating (galvanized or brass-plated).

[0008] The at least two other layers of the reinforcement layer are formed from vulcanized elastomer mixtures (also referred to as rubber sheets or elastomer sheets). According to the invention, the elastomer mixture is based on at least one rubber. For example, it can comprise one or more rubbers selected from the group consisting of natural rubber (NR), acrylonitrile-butadiene rubber (NBR), (partially) hydrogenated acrylonitrile-butadiene rubber (HNBR), styrene-butadiene rubber (SBR), ethylene-propylene-diene rubber (EPDM) / ethylene-propylene rubber (EPM), butadiene rubber (BR), chlorinated polyethylene (CM), chlorosulfonated polyethylene (CSM), or mixtures thereof. Preferably, one or more rubbers are selected from the group consisting of acrylonitrile butadiene rubber (NBR) and / or (partially) hydrogenated acrylonitrile butadiene rubber (HNBR), chlorinated polyethylene (CM) and / or chlorosulfonated polyethylene (CSM), or mixtures thereof.In advantageous embodiments, the elastomer mixture has a glass transition temperature of less than or equal to -30°C, preferably less than or equal to -35°C, more preferably less than or equal to -40°C. The glass transition temperature is the temperature at which a (partially) amorphous solid (e.g. an elastomer) transitions from a rigid, glassy state to a soft, rubbery state. The glass transition temperature of an elastomer is always below the application temperature, i.e. at the service temperature the elastomer is in a soft and rubber-elastic state. For example, in the case of NBR or HNBR, a low acrylonitrile content (max. 30% ACN) should be selected, since the glass transition temperature increases proportionally to the acrylonitrile content. Alternatively or additionally, the glass transition temperature can be reduced by blending the polymer with short-chain components of the same polymer.By selecting elastomer compounds that are still rubber-elastic at -40°C and do not solidify like glass (i.e. break or crack), the flexibility of the high-pressure hose is guaranteed even at low temperatures.

[0009] In preferred embodiments, the reinforcement layer has at least eight layers, preferably at least ten layers, and is formed from the alternating arrangement of a layer of an elastomer mixture (2a) and a directly following layer of a spirally arranged metal wire (2aa). In embodiments with eight layers, the reinforcement layer thus begins with a first layer of an elastomer mixture, followed by a second layer of a spirally arranged metal wire, followed again by a third layer of an elastomer mixture and a fourth layer of the metal wire, etc., until the eighth layer of a metal wire completes the reinforcement layer. This ensures that an elastomer layer is located between all reinforcement layers. This has the advantage of preventing mutual damage to the reinforcement layers when the hose moves.The increased torsion resistance therefore leads to an extended service life of the hose.

[0010] In advantageous embodiments, the spirally arranged metal wires are coated with an adhesion promoter, particularly based on zinc and / or brass. Adhesion promoters serve to create a close physical or chemical bond at the interface of immiscible materials and are generally known. In the case of steel wires, it is particularly advantageous if the steel is coated with a corrosion-protection layer that simultaneously enables bonding to the rubber matrix. Alternatively or additionally, the adjacent elastomer mixtures can already have an adhesion promoter system before they are finally crosslinked. In principle, all adhesion promoters known to a person skilled in the art can be used. Such an adhesion promoter can, for example, be selected from the group consisting of zinc diacrylate, hexamethoxymethylmelamine (HMMM) / silica formaldehyde, sulfur compounds, or mixtures thereof.The individual reinforcement layers are bonded together by the elastomeric interlayers, using a zinc diacrylate, HMMM / silica-formaldehyde adhesion promoter, or a sulfur additive in the formulation of the adjacent elastomer compound. This results in a composite body that separates the reinforcement layers while still maintaining excellent interlayer adhesion, thus enabling an extended service life.

[0011] According to the invention, only the inner barrier layer comprises a plastic that includes a thermoplastic polymer as the main component. A component is referred to below as a main component if the properties of the material mixture are predominantly defined by this component. For example, the main component is present in a mixture at a level of at least 50 wt. %, preferably at least 65 wt. %, more preferably at least 80 wt. %, in each case based on the total mass of the mixture. A thermoplastic component, in particular PA9T and PK, is preferably selected for the inner layer. These can additionally include an elastomer. Exemplary elastomers for use in the inner layer are butyl rubber (HR, OHR, BUIR) and / or EPDM / EPM.

[0012] Previous work (WO 2022 / 135637 A1) has shown that using a thermoplastic polymer with a high degree of crystallinity for the inner layer results in a significant advantage in terms of hydrogen barrier properties. The properties of solids depend to a large extent on the arrangement of the particles (atoms and molecules) that compose the material. If the arrangement is random, the material is amorphous. In crystalline materials, the particles are arranged at regular intervals and in a fixed pattern. While cross-linked polymers (thermosets, thermosetting elastomers) always have an amorphous structure, crystals can form in thermoplastic polymers. In most cases, regions with a crystalline and amorphous structure form side by side. In this case, semi-crystalline plastics are present. The extent of crystallization depends on the conditions under which the plastics solidify.The temperature during solidification and the rate of temperature change have a decisive influence.

[0013] Crystallinity (synonyms: degree of crystallinity and degree of crystallization) is a material property that is particularly important for thermoplastic polymer materials. It indicates the percentage of the polymer that is crystalline and is determined by comparing the measured specific enthalpy of fusion AH with the approximate enthalpy of fusion of the fully crystalline material AHO. The specific enthalpy of fusion is measured using differential scanning calorimetry (DSC), with the crystallinity Xc being derived from the following mathematical relationship:

[0014] The organic and inorganic phases, such as rubber, fillers and reinforcing materials, which do not contribute to the determination of the crystalline fraction of the polymer phase under investigation in heterogeneous polymer materials, can easily be taken into account.

[0015] According to the invention, the thermoplastic polymers used for the inner layer have a crystallinity of greater than or equal to 20%. In preferred embodiments, the crystallinity of the polymers used for the inner layer is greater than or equal to 40%, in particular greater than or equal to 50%. The higher the crystallinity of the polymer, the greater the dimensional stability and resistance to mechanical wear. At the same time, however, the thermal expansion coefficient and the penetration capacity of liquids and gases decrease. Therefore, the polymers of the inner layer have a crystallinity of less than or equal to 90%, preferably less than or equal to 80%, more preferably less than or equal to 70%.

[0016] According to the invention, the inner layer has a single or multi-layer structure. In preferred embodiments, the total thickness of the inner layer is less than or equal to 2.00 mm, but greater than or equal to 0.10 mm. In preferred embodiments, the total thickness of the inner layer is less than or equal to 1.00 mm, preferably less than or equal to 0.75 mm. The use of an inner layer material with increased permeation resistance makes it possible to choose the wall thickness of the inner layer as small as possible, so that the flexibility of the hose is impaired as little as possible by the rigid material of the inner layer. It is advantageous if the polymer itself also has a low electrical resistance, which ensures that charge carriers are dissipated, i.e. is antistatic, e.g. according to ISO_19880-5. Low electrical resistance in this case means a value of no greater than 100 kΩ.

[0017] As polymers for the inner layer, preferably any thermoplastic material with a degree of crystallinity greater than or equal to 20% can be used, either alone or in combination. These are preferably thermoplastic polyurethanes (TPU), polyoxymethylenes (POM), polyamides, ethylene-vinyl alcohol (EVOH), thermoplastic fluoroelastomer vulcanizate (F-TPV), polyvinylidene fluoride (PVDF), or polyethylenes (PE), such as HDPE. These can be used alone or in combination. PA9T and / or PK are preferred.

[0018] When a combination is used, the degree of crystallinity refers to the combination, i.e. the blend, of the two materials.

[0019] The individual layers of the inner layer can be qualitatively and / or quantitatively identical or different from one another in terms of their composition.

[0020] In preferred embodiments, a single- or multi-layer intermediate layer comprising at least one layer of a natural or synthetic textile reinforcement is arranged between the inner layer and the first layer of the reinforcement layer, wherein the modulus of elasticity (E-modulus) of the intermediate layer must be greater than the E-modulus of the reinforcement layer. The modulus of elasticity is a material characteristic that, in the case of linear-elastic behavior, describes the proportional relationship between stress and strain during the deformation of a solid body. The higher the E-modulus value, the stiffer the material. Simply put, the E-modulus is a characteristic value for how much a material yields under the action of force (resistance to deformation). For the same load and geometry, a component made of an elastomer will yield more than a component made of a thermoplastic or steel. A lower E-modulus (e.g.PES has a modulus of elasticity of approximately 1000-5000 N / mm. 2 ) the lower layer has a higher elongation than the steel strength layer above it (e.g. steel has an E-modulus of approx. 200,000 N / mm 2 ).

[0021] This allows it to absorb the high internal operating pressure and transfer it more evenly to the layers above. By using the additional intermediate layer between the inner layer and the actual reinforcement layer, the high internal pressure is equalized, ensuring a homogeneous pressure distribution. In this design, the elastic modulus of this layer must be higher than the actual reinforcement layer to ensure this effect.

[0022] Textile reinforcements are defined here as fabrics made from textiles, typically according to ASTM D123-19. All materials suitable for composites can be used as textile reinforcements. Such materials can include fibers made of polyester, PVAL, lyocell, hemp, aramid, polyamide, rayon, PPS, or mixtures thereof. These materials are used in the form of filaments, fibers, cords, woven fabrics, knitted fabrics, or nonwovens. In particular, the textile reinforcement is a woven or braided fabric.

[0023] A preferred embodiment involves using polyester or polyamide fabrics, or blends of these. These fabrics have the advantage of not only being economically attractive but also combining high tensile strength with good flexibility.

[0024] The intermediate layer is single-layer or multi-layered. The intermediate layer preferably comprises at least a first layer of an elastomer mixture and a second layer of a natural or synthetic textile reinforcement, in particular a polyester fabric or polyester braid. The first layer of the intermediate layer can be arranged between the inner layer and the second layer of the intermediate layer. Any number of additional layers can follow the second layer of the intermediate layer. Preferably, the second layer is also the last layer of the intermediate layer and borders the first layer of the reinforcement layer.

[0025] The elastomer mixture for the first layer of the intermediate layer can have essentially the same composition as the elastomer mixture of the reinforcement layer.

[0026] There is a sufficiently good adhesive bond between the layers of the intermediate layer. In preferred embodiments, this is induced by integrating known adhesion promoter systems, e.g. resorcinol-formaldehyde latex, silanized adhesion promoters or suitable silicon-containing polymer dispersions according to DE 10 2015 21 15 19, between the respective layers. The hose according to the invention additionally contains at least one cover layer, which comprises the outermost layer of the hose. According to the invention, the outer layer is composed of a second polymer mixture. The second polymer mixture differs from the polymer mixture of the inner layer. This is preferably at least one elastomer or a combination, i.e. a blend, of at least one elastomer and / or at least one thermoplastic. These are preferably FKM, SBR, BR, NR, NBR, HNBR, AEM, ACM, ECO, CM, CR, CSM, EPDM / EPM, PU, ​​TPU, POM, TPV, PVC, polyamides, such as, for example,PA6, PA11, PA12, which can each be used alone or in combination. In particularly preferred embodiments, the material of the cover layer is an elastomer mixture comprising an elastomer as the main component. In particular, these elastomer mixtures have a glass transition temperature of less than or equal to -30°C, preferably less than or equal to -35°C, and most preferably less than or equal to -40°C. This has the advantage that the hose remains flexible even at very low operating temperatures, and the material does not exhibit cracks or, in the worst case, break.

[0027] The cover layer has a single or multi-layer structure and is advantageously extruded or wound. In a particularly preferred embodiment, the cover layer is pricked, i.e., perforated, to prevent gas accumulation in the individual layers or between the layers, which in the worst case could lead to failures, for example, due to delamination.

[0028] The high-pressure hose according to the invention can be used in many applications that require the passage of a fluid, in particular a technical gas. Technical gases are gases that are produced and used on an industrial scale. Examples of technical gases are oxygen, nitrogen, argon, xenon, neon, carbon dioxide, acetylene, hydrogen, helium, or mixtures thereof. Refrigerants such as R744 (CO2), Y1234, ammonia, and hydrocarbons such as CNG, LNG, and LPG can also be used. The high-pressure hose according to the invention has an inner diameter of 6 mm to 5 cm.

[0029] Due to its high flexibility, especially at low temperatures (e.g., below 20°C), while simultaneously tolerating high pressures, the hose is particularly suitable for the transport of hydrogen. One embodiment of the invention envisages the use of the described high-pressure hose for refueling hydrogen vehicles or hydrogen aircraft, as well as in the associated infrastructure, such as filling stations and supply vehicles.

[0030] The invention will now be explained using schematic drawings.

[0031] Figure 1 shows a first embodiment of the high-pressure hose according to the invention.

[0032] Figure 2 shows a second embodiment of the high-pressure hose according to the invention, which has an intermediate layer.

[0033] The high-pressure hose according to a first exemplary embodiment (Figure 1) has a single-layer inner layer (1) and a single-layer cover layer (3). The reinforcement layer (2) here is formed in eight layers (2a, 2aa, 2b, 2bb, 2c, 2cc, 2d, 2dd) and is arranged between the inner layer (1) and the cover layer (3). The eight layers are arranged alternately within the reinforcement layer (2) such that the first elastomer layer (2a) represents the first layer (the innermost layer) of the reinforcement layer (2) and a metal layer (2dd) represents the last layer (the outermost layer) of the reinforcement layer (2).

[0034] The inner layer (1) of the hose shown as an example in Figure 1 comprises a layer of a thermoplastic polymer mixture with a degree of crystallinity greater than 20%. The reinforcement layers (2aa, 2bb, 2cc, 2dd) are each formed from steel wires arranged spirally around the hose. The rotation of the steel spiral layers is alternately left or right. For example, if the second layer (2aa) has a left-hand twist, the following metal layer (fourth layer, 2bb) has a right-hand twist, the sixth layer (2cc) again has a left-hand twist, and the eighth layer (2dd) again has a right-hand twist. The cover layer (3) comprises a layer of an elastomer mixture.

[0035] The exemplary high-pressure hose according to the second embodiment (Figure 2) differs from the high-pressure hose of the first embodiment (Figure 1) in that it has an intermediate layer (4). The intermediate layer (4) shown is formed in two layers. In this example, the first layer (4a) is made of an elastomer mixture, and the second layer (4aa) is made of a polyester fiber reinforcement. Table 1 shows the results of a bending test (DIN EN ISO 178).

[0036] Table 1 : Bending tests at different temperatures All three hoses (hoses 1, 2, and 3) have a thermoplastic inner layer. Hose 1 according to the invention differs from hoses 2 and 3 in that all other layers (except for the reinforcement layers) are constructed of elastomers or elastomer blends. Hoses 2 and 3 are hoses from two different manufacturers; both are constructed entirely of thermoplastics, with the reinforcement being a steel wire.

[0037] The results show that the hose 1 according to the invention has a significantly higher flexibility both at room temperature and at very low temperatures, in particular at temperatures below 0°C, since less force has to be applied for bending.

[0038] List of reference symbols

[0039] (part of the description)

[0040] 1 Inner layer 2 Strengthening layer

[0041] 2a first layer of the reinforcement layer

[0042] 2aa second layer of the reinforcement layer

[0043] 2b third layer of the reinforcement layer

[0044] 2bb fourth layer of the reinforcement layer 2c fifth layer of the reinforcement layer

[0045] 2cc sixth layer of the reinforcement layer

[0046] 2d seventh layer of the reinforcement layer

[0047] 2dd eighth layer of the reinforcement layer

[0048] 3 Top layer 4 Intermediate layer

[0049] 4a first layer of the intermediate layer

[0050] 4aa second layer of the intermediate layer

Claims

Patent claims 1. High-pressure hose comprising at least one inner layer (1), at least one four-layer or multi-layer strength-bearing layer (2) and a cover layer (3), wherein the strength-bearing layer (2) is arranged between the inner layer (1) and the cover layer (3), wherein the inner layer (1) comprises a first polymer mixture comprising a thermoplastic polymer with a degree of crystallinity of greater than or equal to 20% and wherein the cover layer (3) comprises a second polymer mixture, characterized in that the strength-bearing layer (2) has at least two layers of a spirally arranged metal wire (2aa, 2bb) and at least two layers of an elastomer mixture (2a, 2b), wherein at least one layer of the elastomer mixture (2b) is arranged between two layers of the spirally arranged metal wire (2aa, 2bb).

2. High-pressure hose according to claim 1, characterized in that the polymer mixture of the cover layer (3) and / or the elastomer mixture of the reinforcement layer (2) comprises at least one elastomer mixture with a glass transition temperature of less than or equal to -30°C.

3. High-pressure hose according to one of claims 1 or 2, characterized in that a single-layer or multi-layer intermediate layer (4) comprising at least one layer of a natural or synthetic textile reinforcement is arranged between the inner layer (1) and the first layer of the reinforcement layer (2a), wherein the modulus of elasticity of the intermediate layer must be greater than the modulus of elasticity of the reinforcement layer (2).

4. High-pressure hose according to claim 3, characterized in that the textile reinforcement comprises fibers made of polyester, PVAL, aramid, polyamide, rayon, PPS or mixtures thereof.

5. High-pressure hose according to claim 4, characterized in that the textile reinforcement comprises fibers made of PA or PES.

6. High-pressure hose according to one of claims 1 to 5, characterized in that the intermediate layer (4) comprises at least a first layer of an elastomer mixture (4a) and a second layer of a natural or synthetic textile Strength member , (4aa).

7. High-pressure hose according to one of claims 1 to 6, characterized in that the reinforcement layer (2) is formed in at least eight layers, preferably in at least ten layers, from the alternating arrangement of a layer of an elastomer mixture (2a) and a directly following layer of a spirally arranged metal wire (2aa).

8. High-pressure hose according to one of claims 1 to 7, characterized in that the elastomer mixture of the strength carrier layer (2) comprises at least one elastomer selected from the group consisting of natural rubber (NR), acrylonitrile-butadiene rubber (NBR), (partially) hydrogenated acrylonitrile-butadiene rubber (HNBR), styrene-butadiene rubber (SBR), ethylene-propylene-diene rubber (EPDM) / ethylene-propylene rubber (EPM), butadiene rubber (BR), chlorinated polyethylene (CM), chlorosulfonated polyethylene (CSM), or mixtures thereof.

9. High-pressure hose according to one of claims 1 to 8, characterized in that the spirally arranged metal wires are coated with an adhesion promoter.

10. Use of a high-pressure hose according to one of claims 1 to 9 for refueling hydrogen vehicles or hydrogen aircraft.

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