Halogen-free low-smoke flame-retardant cable resistant to cold of-52 DEG C

Abstract

The invention discloses a-52 DEG C cold-resistant halogen-free low-smoke flame-retardant cable, relates to the technical field of cables, and solves the problems that a low-smoke flame-retardant cable in the prior art is insufficient in cold resistance, and a sheath is embrittled and cracked in an extremely cold environment to cause laying failure. Comprising a plurality of conductors distributed in an array mode, insulating layers arranged outside the conductors and shielding layers wrapping the insulating layers. The cable further comprises an outer protection layer structure arranged outside the shielding layer, the outer protection layer structure comprises a low-smoke halogen-free polyolefin sheath, a filling layer, an inner flame-retardant layer, a cold-resistant enhancement layer and a compression-resistant buffer layer, the shielding layer is wrapped with the inner flame-retardant layer, and the compression-resistant buffer layer is arranged outside the inner flame-retardant layer; according to the cable scheme, on one hand, heat conduction is effectively reduced, and the internal structure is protected against the influence of extreme temperature; and on the other hand, the cable has good flexibility and mechanical damage resistance, so that the service life of the cable is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of cables, and in particular relates to a -52°C cold-resistant halogen-free low-smoke flame-retardant cable. Background Art

[0002] As the core carrier of power and information transmission, cables are used in extreme environments such as power transmission, industrial control, high-temperature operations, marine engineering, and ship navigation. Based on insulation materials and functional characteristics, cables are classified into power cables, control cables, high-temperature cables, computer cables, fire-resistant cables, marine cables, mining cables, and aluminum alloy cables.

[0003] At present, in order to adapt to different environmental requirements, existing technologies have solved the combustion pollution problem through material modification (such as halogen-free / low-halogen flame-retardant cloth), but still face the following technical problems in ultra-low temperature scenarios.

[0004] Existing flame-retardant cables generally use halogen-free or low-halogen flame-retardant cloth as the fireproof layer. Although it can reduce combustion pollution, in extremely cold environments, traditional plastic and rubber sheaths will become brittle, crack, or even fall off. During installation, the insulation layer and sheath are very easy to break, resulting in exposed conductors and cable scrapping, seriously affecting the progress of the project and causing inconvenience to residents' lives.

[0005] In summary, the flame-retardant cables in the prior art have the problems of insufficient cold resistance and laying failure due to brittle cracking of the sheath in extremely cold environments. Summary of the Invention

[0006] The present invention provides a -52°C cold-resistant halogen-free low-smoke flame-retardant cable, which can solve the problems of insufficient cold resistance and laying failure caused by embrittlement and cracking of the sheath in extremely cold environments in the existing low-smoke flame-retardant cable.

[0007] To achieve the above object, according to an embodiment of the first aspect of the present invention, a -52°C cold-resistant halogen-free low-smoke flame-retardant cable is provided, comprising a plurality of conductors distributed in an array, an insulating layer disposed outside each conductor, and a shielding layer wrapped around the insulating layer; Also includes: The outer sheath structure is arranged on the outside of the shielding layer, and the outer sheath structure includes a low-smoke halogen-free polyolefin sheath, a filling layer, an inner flame retardant layer, a cold-resistant reinforcement layer and a pressure-resistant buffer layer. The inner flame retardant layer is wrapped on the outside of the shielding layer, the pressure-resistant buffer layer is arranged on the outside of the inner flame retardant layer, the cold-resistant reinforcement layer is arranged between the outside of the inner flame retardant layer and the inside of the pressure-resistant buffer layer, the low-smoke halogen-free polyolefin sheath is wrapped on the outside of the pressure-resistant buffer layer, and the filling layer is arranged between the insulating layer and the shielding layer.

[0008] A further improvement is that each of the conductors is formed by twisting multiple strands of copper-nickel alloy gold wires.

[0009] A further improvement is that the insulating layer includes an insulating inner layer and an insulating outer layer, the insulating inner layer is made of elastic EPDM material and is evenly wrapped around the outside of each conductor, and the insulating outer layer is made of flame-retardant cross-linked polyethylene material and is evenly wrapped around the outside of the insulating inner layer.

[0010] A further improvement is that the shielding layer is a tinned copper tape, which is wrapped around the outside of the insulating outer layer by wrapping.

[0011] A further improvement is that the cold-resistant reinforcement layer is made of a composite of cross-linked polyethylene and nano-silicon dioxide.

[0012] A further improvement is that the inner flame retardant layer is made of silicone rubber and the filling layer is halogen-free flame retardant glass fiber rope.

[0013] A further improvement is that the compression buffer layer is formed by compounding thermoplastic polyurethane elastomer and aluminum-magnesium alloy woven mesh.

[0014] A further improvement is that an oxygen-isolating layer and a thermal insulation layer are provided on the inner side of the low-smoke halogen-free polyolefin sheath, the thermal insulation layer is wrapped around the outside of the pressure-resistant buffer layer, and the oxygen-isolating layer is wrapped around the outside of the thermal insulation layer, the oxygen-isolating layer is made of aerogel felt, and the thermal insulation layer is composited from thermoplastic elastomer and polyurethane film.

[0015] A further improvement is that the outer sheath structure further includes a torsional reinforcement layer, which is wrapped around the outside of the cold-resistant reinforcement layer and the inside of the pressure-resistant buffer layer, and the torsional reinforcement layer is woven with aramid fibers.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention twists each conductor with multiple strands of copper-nickel alloy gold wire, and then presses the twisted conductors after gluing. This design can reduce the gaps between conductors, reduce the low-temperature shrinkage rate, improve the conductor's resistance to brittleness at cold temperatures, improve the flexibility of the cable, prevent the insulation layer from cracking due to conductor shrinkage, and prevent it from breaking when bent or vibrated. The inner insulating layer and the outer insulating layer are designed as the insulation layer outside the conductor. The inner insulating layer is made of elastic EPDM rubber and is evenly wrapped around the outside of each conductor to provide flexible support. The outer insulating layer is made of flame-retardant cross-linked polyethylene and is evenly wrapped around the outside of the inner insulating layer as a rigid barrier to block flames, mechanical impact and environmental erosion. The insulating layer adopts a double-layer design. In terms of protection, the two form a "soft-hard" composite structure, which not only ensures the bending freedom of the cable, but also improves the overall protection level. In terms of electrical performance, the elastic EPDM rubber material and the flame-retardant cross-linked polyethylene material both have low dielectric constants. The electrical performance of the composite structure does not interfere with each other, ensuring signal transmission efficiency and insulation reliability. Compared with a single thick-walled flame-retardant material, the composite structure reduces material usage through a layered design. At the same time, the lightweight properties of the elastic EPDM rubber material help reduce the overall weight of the cable, making it easier to install and transport.

[0017] In addition, a shielding layer is designed outside the insulation layer. The insulation layer consists of tinned copper tape, which is wrapped around the outer insulation layer. This not only allows the flame-retardant cable to withstand external mechanical pressure and prevent the insulation layer from being crushed or scratched, but also effectively isolates the copper from contact with air and moisture, avoiding oxidative corrosion caused by low-temperature condensation. Compared with braided shielding, the wrapped structure is less likely to deform when the cable is twisted, maintaining the integrity of the shielding layer. At the same time, a halogen-free flame-retardant glass fiber rope is designed as a filling layer to fill the gap between the insulation layer and the shielding layer and enhance flame retardancy.

[0018] (2) The present invention designs an outer sheath structure composed of a low-smoke halogen-free polyolefin sheath, a filling layer, an inner flame-retardant layer, a cold-resistant reinforcement layer, a pressure-resistant buffer layer, an oxygen-isolating layer, a thermal insulation layer, and a torsional reinforcement layer, which is wrapped around the outside of the flame-retardant cable as external protection. The cold-resistant reinforcement layer is made of a composite of cross-linked polyethylene and nano-silicon dioxide. With the help of the resilience of the elastomeric material, the reinforcement layer can effectively offset the shrinkage stress generated in a low-temperature environment, thereby preventing the cable from cracking due to thermal expansion and contraction. The design uses silicone rubber material to make the inner flame-retardant layer. The silicone rubber material of the inner flame-retardant layer and the halogen-free polyolefin sheath form an inner and outer double-layer flame-retardant protective structure, which can improve the cold resistance and flame-retardant reliability of the cable in extremely cold environments. The oxygen-isolating layer is made of aerogel felt, which can reduce the risk of combustion through physical barrier and heat absorption, thereby effectively delaying the spread of flames. The thermal insulation layer is made of thermoplastic elastomer and polyurethane film, forming a multi-layer composite belt structure. On the one hand, it effectively reduces heat conduction and protects the internal structure from extreme temperatures; on the other hand, it has good flexibility and resistance to mechanical damage, thereby extending the service life of the cable.

[0019] In addition, the design utilizes a composite of thermoplastic polyurethane elastomer and aluminum-magnesium alloy braided mesh as a compressive buffer layer. The thermoplastic polyurethane elastomer absorbs low-temperature shrinkage stress, preventing internal stress from being transferred to the outer sheath. The aluminum-magnesium alloy braided mesh provides support, dissipates localized pressure, and enhances tear resistance, preventing cracking and expansion in the sheath in extremely cold conditions. Furthermore, the design is lightweight and offers excellent impact resistance. A torsion reinforcement layer, wrapped around the cold-resistant reinforcement layer, serves as structural reinforcement. This torsion reinforcement layer is woven from aramid fiber, enhancing the cable's torsion resistance, allowing it to withstand repeated torsioning without damage, further extending its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the inner cable core and outer sheath of the cable of the present invention; Figure 2 It is a schematic diagram of the overall cross-sectional structure of the cable of the present invention.

[0021] Markings in the figure: 1. Conductor; 11. Insulation layer; 101. Insulation inner layer; 102. Insulation outer layer; 12. Shielding layer; 2. Outer sheath structure; 21. Low-smoke halogen-free polyolefin sheath; 22. Filling layer; 23. Inner flame-retardant layer; 24. Cold-resistant reinforcement layer; 25. Compression buffer layer; 26. Thermal insulation layer; 27. Oxygen barrier layer; 28. Torsion reinforcement layer. DETAILED DESCRIPTION

[0022] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] like Figure 1 and Figure 2 As shown, a -52°C cold-resistant halogen-free low-smoke flame-retardant cable comprises a plurality of conductors 1 distributed in an array, an insulating layer 11 arranged outside each conductor 1, and a shielding layer 12 wrapped around the insulating layer 11; Each conductor 1 is made of multiple strands of copper-nickel alloy gold wire. After gluing, the stranded conductors 1 are pressed tightly. This design can reduce the gaps between the conductors 1, reduce the low-temperature shrinkage rate, improve the brittleness of the conductors 1 in cold temperatures, improve the flexibility of the cable, prevent the insulation layer 11 from cracking due to the shrinkage of the conductors 1, and prevent breakage during bending or vibration. As a preferred embodiment, the insulating layer 11 includes an insulating inner layer 101 and an insulating outer layer 102. The insulating inner layer 101 is made of elastic EPDM rubber and is evenly wrapped around the outside of each conductor 1 to provide flexible support. The insulating outer layer 102 is made of flame-retardant cross-linked polyethylene and is evenly wrapped around the outside of the insulating inner layer 101 to serve as a rigid barrier to block flames, mechanical impact and environmental erosion.

[0024] It should be noted that the insulating layer 11 adopts a double-layer design. In terms of protection, the two layers form a "soft-hard" composite structure, which not only ensures the bending freedom of the cable, but also improves the overall protection level. In terms of electrical performance, the elastic EPDM rubber material and the flame-retardant cross-linked polyethylene material both have low dielectric constants. Under their composite structure, the electrical properties do not interfere with each other, ensuring signal transmission efficiency and insulation reliability. Compared with a single thick-walled flame-retardant material, the composite structure reduces material consumption through a layered design. At the same time, the lightweight properties of the elastic EPDM rubber material help reduce the overall weight of the cable, facilitating installation and transportation: As a preferred embodiment, the shielding layer 12 is a tinned copper tape, which is wrapped around the outside of the insulating outer layer 102. The tinned copper tape can withstand external mechanical pressure, prevent the insulating layer 11 from being flattened or scratched, and effectively isolate the copper from contact with air and moisture, avoiding oxidative corrosion caused by low-temperature condensation. Compared with braided shielding, the wrapped structure is not easily deformed when the cable is twisted, maintaining the integrity of the shielding layer 12. The outer sheath structure 2 is arranged on the outside of the shielding layer 12. The outer sheath structure 2 includes a low-smoke halogen-free polyolefin sheath 21, a filling layer 22, an inner flame-retardant layer 23, a cold-resistant reinforcement layer 24 and a pressure-resistant buffer layer 25. The inner flame-retardant layer 23 is wrapped around the outside of the shielding layer 12, the pressure-resistant buffer layer 25 is arranged on the outside of the inner flame-retardant layer 23, the cold-resistant reinforcement layer 24 is arranged between the outer side of the inner flame-retardant layer 23 and the inner side of the pressure-resistant buffer layer 25, the low-smoke halogen-free polyolefin sheath 21 is wrapped around the outside of the pressure-resistant buffer layer 25, and the filling layer 22 is arranged between the insulating layer 11 and the shielding layer 12; Specifically, the cold-resistant reinforcement layer 24 is made of a composite of cross-linked polyethylene and nano-silicon dioxide. The reinforcement layer, by virtue of the resilience of the elastomeric material, can effectively offset the shrinkage stress generated in a low-temperature environment, thereby preventing the insulation layer 11 from cracking due to thermal expansion and contraction of the cable. Specifically, the inner flame-retardant layer 23 is made of silicone rubber, and the filling layer 22 is halogen-free flame-retardant fiberglass rope, which is used to fill the gap between the insulation layer 11 and the shielding layer 12 and enhance the flame retardancy. The silicone rubber material of the inner flame-retardant layer 23 and the low-smoke halogen-free polyolefin sheath 21 form an inner and outer double-layer flame-retardant protective structure, which can improve the cold resistance and flame retardant reliability of the cable in extremely cold environments. Specifically, the compressive buffer layer 25 is made of a composite of thermoplastic polyurethane elastomer and aluminum-magnesium alloy braided mesh. The thermoplastic polyurethane elastomer absorbs low-temperature shrinkage stress and prevents internal stress from being transmitted to the outer sheath. The aluminum-magnesium alloy braided mesh provides support, disperses local pressure, improves tear resistance, and prevents cracking and expansion of the sheath in extremely cold environments. It is also lighter and has excellent impact resistance. As a preferred embodiment, an oxygen-isolating layer 27 and a thermal insulation layer 26 are provided on the inner side of the low-smoke halogen-free polyolefin sheath 21. The thermal insulation layer 26 is wrapped around the outside of the pressure-resistant buffer layer 25, and the oxygen-isolating layer 27 is wrapped around the outside of the thermal insulation layer 26. The oxygen-isolating layer 27 is made of aerogel felt, which can reduce the risk of combustion through physical barrier and heat absorption, thereby effectively delaying the spread of flames. The thermal insulation layer 26 is composed of a composite of thermoplastic elastomer and polyurethane film to form a multi-layer composite tape structure. On the one hand, it effectively reduces heat conduction and protects the internal structure from extreme temperatures; on the other hand, it has good flexibility and resistance to mechanical damage, thereby extending the service life of the cable. As a preferred embodiment, the outer sheath structure 2 also includes a torsion-resistant reinforcement layer 28, which is wrapped around the outside of the cold-resistant reinforcement layer 24 and the inside of the pressure-resistant buffer layer 25. The torsion-resistant reinforcement layer 28 is woven with aramid fiber. Such a material can enhance the cable's torsion resistance, allowing the cable to withstand repeated torsion without damage, further extending the cable's service life.

[0025] like Figure 1 and Figure 2As shown in this embodiment, it should be noted that the cable manufacturing in the application document is based on existing production processes. In addition, it should be noted that this application document only addresses the shortcomings of the existing low-smoke flame-retardant cable, such as insufficient cold resistance and sheath embrittlement and cracking in extremely cold environments, which leads to installation failure, and does not involve other aspects. The working principle of this -52℃ cold-resistant halogen-free low-smoke flame-retardant cable is described as follows: The cable solution of the present invention is to improve the cable core structure and outer sheath simultaneously, specifically: The cable core structure is designed as follows: Each conductor 1 is twisted together using multiple strands of copper-nickel alloy gold wire. After gluing, the twisted conductors 1 are compacted. This reduces gaps between the conductors 1, reduces low-temperature shrinkage, improves the conductors' resistance to cold temperatures, and enhances the cable's flexibility. It prevents the insulation layer 11 from cracking due to conductor shrinkage and fracturing during bending or vibration. The inner insulating layer 101 and the outer insulating layer 102 are designed as the outer insulation layer 11 of the conductors 1. The inner insulating layer 101 is made of elastic EPDM and evenly wraps around each conductor 1, providing flexible support. The outer insulating layer 102 is made of flame-retardant cross-linked polyethylene and evenly wraps around the inner insulating layer 101, acting as a rigid barrier to flame, mechanical impact, and environmental corrosion. The double-layer design of the insulation layer 11 creates a "soft-hard" composite structure, ensuring the cable's bending freedom while enhancing the overall protection level. In terms of electrical performance, both the elastic EPDM and flame-retardant cross-linked polyethylene materials have low dielectric constants. Their composite structure eliminates interference with each other's electrical properties, ensuring efficient signal transmission and reliable insulation. Compared to a single thick-walled flame-retardant material, the composite structure's layered design reduces material usage. The lightweight nature of the elastic EPDM material also helps reduce the overall cable weight, facilitating installation and transportation.

[0026] In addition, a shielding layer 12 is designed outside the insulating layer 11. The insulating layer 11 is made of tinned copper tape and wrapped around the outer insulating layer 102. This allows the flame-retardant cable to withstand external mechanical pressure and prevent the insulating layer 11 from being crushed or scratched. It also effectively isolates the copper from air and moisture, avoiding oxidative corrosion caused by low-temperature condensation. Compared with braided shielding, the wrapped structure is less likely to deform when the cable is twisted, maintaining the integrity of the shielding layer 12. At the same time, a halogen-free flame-retardant glass fiber rope is designed as the filling layer 22, which is used to fill the gap between the insulating layer 11 and the shielding layer 12 and enhance flame retardancy.

[0027] Design of the outer sheath structure 2 of the cable: that is, by designing an outer sheath structure 2 composed of a low-smoke halogen-free polyolefin sheath 21, a filling layer 22, an inner flame-retardant layer 23, a cold-resistant reinforcement layer 24, a pressure-resistant buffer layer 25, an oxygen-isolating layer 27, a thermal insulation layer 26, and a torsional reinforcement layer 28, the outer sheath structure 2 is wrapped around the outside of the flame-retardant cable as external protection. The cold-resistant reinforcement layer 24 is made of a composite of cross-linked polyethylene and nano-silicon dioxide. This reinforcement layer, with the help of the resilience of the elastomeric material, can effectively offset the shrinkage stress generated in low-temperature environments, thereby preventing the insulation layer 11 of the cable from cracking due to thermal expansion and contraction. The inner flame-retardant layer 23 is made of silicone rubber. The silicone rubber material of the inner flame-retardant layer 23 and the low-smoke halogen-free polyolefin sheath 21 form an inner and outer double-layer flame-retardant protective structure, which can improve the cold resistance and flame-retardant reliability of the cable in extremely cold environments. The oxygen-isolating layer 27 is made of aerogel felt, which can reduce the risk of combustion through physical barrier and heat absorption, thereby effectively delaying the spread of flames. The thermal insulation layer 26 is made of a composite of thermoplastic elastomer and polyurethane film, forming a multi-layer composite belt structure. On the one hand, it effectively reduces heat conduction and protects the internal structure from extreme temperatures; on the other hand, it has good flexibility and resistance to mechanical damage, thereby extending the service life of the cable.

[0028] In addition, the design utilizes a composite of thermoplastic polyurethane elastomer and aluminum-magnesium alloy braided mesh as the compressive buffer layer 25. The thermoplastic polyurethane elastomer absorbs low-temperature shrinkage stress, preventing internal stress from being transferred to the outer sheath. The aluminum-magnesium alloy braided mesh provides support, dissipates localized pressure, and enhances tear resistance, preventing cracking and expansion in the sheath in extremely cold environments. Furthermore, the design is lightweight and offers excellent impact resistance. A torsional reinforcement layer 28, wrapped around the cold-resistant reinforcement layer 24, serves as structural reinforcement. Braided from aramid fiber, this material enhances the cable's torsional resistance, allowing it to withstand repeated torsion without damage, further extending its service life.

[0029] The above embodiments are only used to illustrate the technical method of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A cold-resistant -52°C halogen-free low-smoke flame-retardant cable, comprising a plurality of conductors (1) distributed in an array, an insulating layer (11) arranged outside each conductor (1), and a shielding layer (12) wrapped around the outside of the insulating layer (11); It is characterized in that Also includes: An outer sheath structure (2) is arranged outside the shielding layer (12), and the outer sheath structure (2) includes a low-smoke halogen-free polyolefin sheath (21), a filling layer (22), an inner flame-retardant layer (23), a cold-resistant reinforcement layer (24), and a pressure-resistant buffer layer (25), wherein the inner flame-retardant layer (23) is wrapped outside the shielding layer (12), the pressure-resistant buffer layer (25) is arranged outside the inner flame-retardant layer (23), the cold-resistant reinforcement layer (24) is arranged between the outer side of the inner flame-retardant layer (23) and the inner side of the pressure-resistant buffer layer (25), the low-smoke halogen-free polyolefin sheath (21) is wrapped outside the pressure-resistant buffer layer (25), and the filling layer (22) is arranged between the insulating layer (11) and the shielding layer (12).

2. The -52°C cold-resistant halogen-free low-smoke flame-retardant cable according to claim 1, characterized in that: Each conductor (1) is formed by twisting multiple strands of copper-nickel alloy gold wires.

3. The -52°C cold-resistant halogen-free low-smoke flame-retardant cable according to claim 1, characterized in that: The insulating layer (11) comprises an insulating inner layer (101) and an insulating outer layer (102), wherein the insulating inner layer (101) is made of elastic ethylene propylene rubber and is evenly wrapped around the outside of each conductor (1), and the insulating outer layer (102) is made of flame-retardant cross-linked polyethylene and is evenly wrapped around the outside of the insulating inner layer (101).

4. The -52°C cold-resistant halogen-free low-smoke flame-retardant cable according to claim 3, characterized in that: The shielding layer (12) is a tinned copper tape, which is wrapped around the outside of the insulating outer layer (102).

5. The -52°C cold-resistant halogen-free low-smoke flame-retardant cable according to claim 1, characterized in that: The cold-resistant reinforcement layer (24) is made of a composite of cross-linked polyethylene and nano-silicon dioxide.

6. The -52°C cold-resistant halogen-free low-smoke flame-retardant cable according to claim 1, characterized in that: The inner flame retardant layer (23) is made of silicone rubber, and the filling layer (22) is halogen-free flame retardant glass fiber rope.

7. The -52°C cold-resistant halogen-free low-smoke flame-retardant cable according to claim 1, characterized in that: The compression-resistant buffer layer (25) is formed by compounding thermoplastic polyurethane elastomer and aluminum-magnesium alloy braided mesh.

8. The -52°C cold-resistant halogen-free low-smoke flame-retardant cable according to claim 7, characterized in that: An oxygen-isolating layer (27) and a thermal insulation layer (26) are provided on the inner side of the low-smoke halogen-free polyolefin sheath (21), the thermal insulation layer (26) is wrapped around the outside of the pressure-resistant buffer layer (25), and the oxygen-isolating layer (27) is wrapped around the outside of the thermal insulation layer (26), the oxygen-isolating layer (27) is made of aerogel felt, and the thermal insulation layer (26) is made of a composite of thermoplastic elastomer and polyurethane film.

9. The -52°C cold-resistant halogen-free low-smoke flame-retardant cable according to claim 7, characterized in that: The outer sheath structure (2) further comprises a torsion-resistant reinforcement layer (28), which is wrapped around the outside of the cold-resistant reinforcement layer (24) and the inside of the pressure-resistant buffer layer (25), and the torsion-resistant reinforcement layer (28) is woven from aramid fibers.

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