Termite-proof cable and preparation method thereof

Abstract

The invention relates to the technical field of cables, and provides a termite-proof cable and a preparation method thereof, and the termite-proof cable sequentially comprises a conductor, an insulating layer, an inner sheath, an MCP composite sheath, an armor layer and an outer sheath from inside to outside; the MCP composite protective layer sequentially comprises a first sub-layer, a second sub-layer, a third sub-layer and a fourth sub-layer from inside to outside, the first sub-layer adopts an aluminum-plastic composite belt, the second sub-layer adopts a high-density polyethylene nano composite material, the third sub-layer adopts a termite-proof polyamide material, and the fourth sub-layer adopts a termite-proof polyamide material. And the fourth sub-layer is made of a linear low-density polyethylene functional composite material. The invention is used for solving the problems that the existing termite-proof oil and gas cable sheath technology replacing the traditional lead sheath cannot meet the requirements of environmental protection, high efficiency, economical efficiency and full-life-cycle protection reliability at the same time, and termite invasion in the underground laying process of the oil and gas cable is difficult to effectively solve. And an environment-friendly, efficient and economical termite-proof cable structure is developed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cables, in particular to an anti-termite cable and a preparation method thereof. BACKGROUND

[0002] In the fields of oil and gas resource exploration and development, transportation and distribution, oil and gas cables are widely laid underground as key energy transmission and signal control carriers to adapt to complex site environments and reduce the occupation of ground facilities. However, termites are active in underground environments, and the sheath structure of oil and gas cables is easily damaged by termite bites, which can easily lead to the exposure of the internal conductor of the cable, insulation failure, and safety accidents such as short circuit and electric leakage. In addition, termite bites can also damage the sealing performance of the cable, allowing moisture and soil impurities to enter and accelerate the aging and corrosion of the cable, thereby seriously affecting the operational stability and service life of the oil and gas cable. Therefore, anti-termite protection is one of the technical problems that must be solved in the design and preparation process of underground laid oil and gas cables.

[0003] To address the threat of termite infestation, lead sheaths are commonly used as anti-termite protective layers in traditional technical solutions. However, lead materials pose significant hazards to the environment and human health, and traditional lead sheath anti-termite solutions cannot meet modern environmental protection requirements. Therefore, developing environmentally friendly, efficient, and economical alternative anti-termite cable sheath technologies has become an urgent need for the development of the oil and gas cable industry.

[0004] Currently, a series of explorations have been conducted to replace lead sheaths for anti-termite solutions, but these solutions have their own limitations and have not achieved the comprehensive goals of environmental protection, efficiency, and economy. Specifically, these solutions have the following problems: Single-layer high-hardness plastic sheath solution: This solution resists termite bites by increasing the hardness of the sheath material. However, it has the following problems: On the one hand, the increase in material hardness inevitably leads to a decrease in cable flexibility, making the cable's bending performance worse and making it difficult to construct and install. On the other hand, high-hardness plastic sheaths are prone to surface scratches or local damage due to collisions or friction during construction or maintenance, and termites can easily invade and continuously bite through these damaged areas, leading to the failure of anti-termite protection. In addition, plastic materials can be affected by factors such as temperature changes, humidity erosion, and ultraviolet radiation during long-term service in the underground environment, leading to aging, a gradual decline in material hardness and mechanical properties, and a decrease in anti-termite performance, making it difficult to meet the protection needs of the entire life cycle of the cable.

[0005] Single sheath solution of adding chemical termite prevention agent: repel or kill termites by adding chemical termite prevention agent in plastic sheath base material, but there are many deficiencies: first, the chemical termite prevention agent is easy to migrate and precipitate in the sheath material, and the content of the termite prevention agent in the sheath gradually decreases with the extension of the use time, resulting in continuous attenuation of the termite prevention effect and poor long-term protection stability; second, most of the high-efficiency chemical termite prevention agents have environmental pollution problems; third, single material is difficult to meet the requirements of mechanical properties, termite prevention performance and environmental protection at the same time.

[0006] Metal armored sheath solution: stainless steel belt or steel wire armor is used to replace lead sheath, which solves the environmental protection problem, but has the following defects: cost is greatly increased, cable weight is increased, installation difficulty is increased, production process is complex, and efficiency is low.

[0007] Therefore, developing an anti-termite cable protection structure which has the advantages of environmental protection, long-term and stable termite prevention effect, excellent mechanical protection performance, controllable production cost and adaptation to underground laying construction requirements to replace the traditional lead sheath has become a technical problem to be solved in the field. SUMMARY

[0008] The present application provides an anti-termite cable and a preparation method thereof, to solve the problem that the existing anti-termite oil and gas cable sheath technology which replaces the traditional lead sheath cannot meet the requirements of environmental protection, high efficiency, economy and reliable protection in the whole life cycle at the same time, and cannot effectively solve the termite damage problem in the process of underground laying of oil and gas cable, and to develop an environmentally friendly, efficient and economical anti-termite cable structure.

[0009] The present application provides an anti-termite cable, which comprises, from inside to outside, a conductor, an insulation layer, an inner sheath, an MCP composite sheath layer, an armored layer and an outer sheath. The MCP composite sheath layer comprises, from inside to outside, a first sub-layer, a second sub-layer, a third sub-layer and a fourth sub-layer, the first sub-layer is made of aluminum plastic composite tape, the second sub-layer is made of high-density polyethylene nano composite material, the third sub-layer is made of anti-termite polyamide material, and the fourth sub-layer is made of linear low-density polyethylene functional composite material.

[0010] According to the anti-termite cable provided by the present application, the second sub-layer comprises the following raw materials in parts by weight: 85-95 parts of high-density polyethylene resin, 2-5 parts of nano silicon dioxide, 1-3 parts of nano montmorillonite, 0.5-1 part of silane coupling agent and 0.3-0.5 part of antioxidant.

[0011] According to the anti-termite cable provided by the present application, the third sub-layer comprises the following raw materials in parts by weight: 80-90 parts of polyamide 12 resin, 1-2 parts of n-nonanoic acid vanillyl amide, 1-2 parts of FYJ-01 anti-termite functional masterbatch and 5-10 parts of glass fiber.

[0012] The fourth sub-layer comprises the following raw materials in parts by weight: linear low-density polyethylene resin 70-80 parts, halogen-free flame retardant 15-20 parts, carbon black 2-3 parts, ultraviolet absorber 0.5-1 part, and lubricant 0.5-1 part.

[0013] The second sub-layer, the third sub-layer and the fourth sub-layer are integrally formed by three-layer co-extrusion.

[0014] The first compatibilizer between the second sub-layer and the third sub-layer is maleic anhydride grafted polyethylene.

[0015] The second compatibilizer between the third sub-layer and the fourth sub-layer is maleic anhydride grafted polypropylene.

[0016] The inner sheath and the outer sheath are made of low-smoke halogen-free flame-retardant polyolefin material, and the armor layer is made of galvanized steel wire armor.

[0017] The cable further comprises a shielding layer, which comprises a partial shielding layer and a total shielding layer, a plurality of conductors form an instrument cable core unit, the outer side of the single instrument cable core unit is provided with the partial shielding layer, and the outer side of the twisted structure formed by the plurality of instrument cable core units is provided with the total shielding layer.

[0018] The application further provides a preparation method of the termite-proof cable. A plurality of tinned copper wires are twisted into a conductor, an insulation layer is extruded outside the conductor, and an inner sheath is extruded outside the insulation layer; The MCP composite sheath is formed, the MCP composite sheath comprises a first sub-layer, a second sub-layer, a third sub-layer and a fourth sub-layer from inside to outside, the first sub-layer is made of aluminum-plastic composite tape, the second sub-layer is made of high-density polyethylene nano-composite material, the third sub-layer is made of termite-proof polyamide material, and the fourth sub-layer is made of linear low-density polyethylene functional composite material, and the MCP composite sheath forming comprises: wrapping the first sub-layer outside the inner sheath, and forming the second sub-layer, the third sub-layer and the fourth sub-layer outside the first sub-layer; An armor layer is twisted outside the MCP composite sheath, and an outer sheath is extruded outside the armor layer.

[0019] The application provides the termite-proof cable and a preparation method thereof, and the MCP composite sheath is arranged, four-layer functional sublayers are cooperated, and the organic unity of the termite-proof performance, the mechanical protection performance, the environmental protection performance and the construction adaptability is realized, wherein the aluminum plastic composite tape can effectively block electromagnetic interference in the underground environment, avoids the influence of the cable signal transmission by the external magnetic field, guarantees the signal stability of the oil and gas cable, can form an initial moisture-proof barrier, delays the aging speed of the insulation layer and the inner sheath, the surface of the aluminum plastic composite tape is smooth and has strong adhesion, stable base support is provided for subsequent extrusion molding of the second sublayer, the delamination and peeling problems between the sublayers are avoided, and the structural integrity of the composite sheath is guaranteed; the high-density polyethylene nano composite material can effectively improve the overall structural strength of the composite sheath, resist external force impact such as extrusion of underground soil and construction dragging, and has excellent elastic buffering performance; the termite-proof polyamide material has high wear resistance, and the environmental protection type termite-proof component is added by modification, the termites are effectively repelled, the component is not easy to migrate and separate out, the problems that the traditional chemical termite-proof agent is effective for a short term and invalid for a long term are solved, and the termite-proof protection of the cable in the whole life cycle is realized; the linear low-density polyethylene functional composite material can provide weather resistance, flame retardation and surface protection effects; and the outer armor layer can further strengthen the mechanical protection capability and resist underground hard object puncture, heavy object impact and other extreme working conditions, and the flexibility of the MCP composite sheath is adjusted, the defects of the metal armored cable, such as large weight and difficult construction, are avoided, and the transportation and laying costs are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0021] Figure 1 It is a structure schematic diagram of the termite-proof cable provided by the application.

[0022] Signs: 10, conductor; 11, insulation layer; 13, inner sheath; 14, armor layer; 15, outer sheath; 16, mica tape; 17, partial shielding layer; 18, total shielding layer; 20, MCP composite sheath; 21, first sublayer; 22, second sublayer; 23, third sublayer; 24, fourth sublayer. DETAILED DESCRIPTION

[0023] In order to make the objects, technical solutions and advantages of the present application clearer, the following will clearly and completely describe the technical solutions in the present application with reference to the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall into the scope of the present application.

[0024] In the description of the present application, it should be understood that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0025] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection, or communication; can be directly connected, or indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0026] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples.

[0027] The following will be described in combination with Figure 1 The term "white ant resistant cable" is described in the present application, which comprises, from inside to outside, a conductor 10, an insulation layer 11, an inner sheath 13, an MCP composite sheath 20, an armor layer 14 and an outer sheath 15; The MCP composite sheath 20 comprises, from inside to outside, a first sub-layer 21, a second sub-layer 22, a third sub-layer 23 and a fourth sub-layer 24, the first sub-layer 21 adopts an aluminum plastic composite tape, the second sub-layer 22 adopts a high-density polyethylene nanocomposite material, the third sub-layer 23 adopts an anti-termite polyamide material, and the fourth sub-layer 24 adopts a linear low-density polyethylene functional composite material.

[0028] The anti-termite cable of the present application can widely cover the underground cable laying needs in multiple fields such as oil and gas industry, urban infrastructure, outdoor new energy, high-end civil and industrial buildings, and is suitable for environmentally friendly cables for oil, natural gas and petrochemical industry instruments, control and communication systems, especially in the working conditions with high termite infestation and complex environment, compared with traditional cables, it has significant performance advantages and application value, can effectively improve the cable operation reliability, prolong the service life, and reduce the operation and maintenance cost and safety risk.

[0029] Specifically, the conductor 10 is twisted by a plurality of copper wires or tinned copper wires, and an insulating layer 11 is arranged outside the conductor 10, the insulating layer 11 can be selected from cross-linked polyethylene material (XLPE), the inner sheath 13 can be selected from low-smoke halogen-free flame-retardant polyolefin material (LSZH), forming an effective inner layer moisture-proof and corrosion-proof barrier, delaying material aging, protecting the long-term stability of the MCP composite sheath 20 anti-termite function, and at the same time having good flame-retardant basis, providing support for the overall flame-retardant performance of the cable; the armor layer 14 can adopt galvanized steel wire armor (GSWA) to provide compression resistance, impact resistance and protection against gnawing animals, and the outer sheath 15 can be selected from low-smoke halogen-free flame-retardant polyolefin material (LSZH) to meet the standards of IEC 60754, IEC 61034 and IEC 60332, and has excellent wear resistance, weather resistance and chemical corrosion resistance, and forms a synergistic protection with the inner sheath 13 to improve the environmental protection and flame-retardant performance. As shown in the figure, the mica tape 16 can be wrapped around the insulating layer 11 outside the conductor 10, and the mica tape 16 forms a buffer isolation layer, which can further improve the high temperature resistance, aging resistance and insulation reliability of the cable. Figure 1 Further, by setting the MCP (Moisture and Chemical Protection) composite sheath, the four layers of sub-layers synergistically enhance each other to build a comprehensive anti-termite protection system.

[0030] As a preferred embodiment, the second sub-layer 22 comprises the following raw materials in parts by weight: high-density polyethylene resin 85-95 parts, nano-silicon dioxide 2-5 parts, nano-montmorillonite 1-3 parts, silane coupling agent 0.5-1 part, and antioxidant 0.3-0.5 part.

[0031] The high-density polyethylene resin (hereinafter referred to as HDPE resin) as the basic framework raw material of the second sublayer 22, with its excellent structural strength, impact resistance and compression resistance, builds a stable intermediate support structure for the MCP composite sheath 20, avoids the deformation of the MCP composite sheath 20 due to external force, and affects the structural integrity between the sublayers, and provides a stable adhesion and dispersion base for the subsequent nano-enhanced materials and functional additives, and ensures the stable play of the overall function of the second sublayer 22; nano-silicon dioxide can enhance the hardness and wear resistance of the material, and uniform dispersion in the HDPE matrix can greatly strengthen the surface hardness and wear resistance of the material, improve the physical penetration resistance of termites, and at the same time improve the dimensional stability of the material, reduce the shrinkage and deformation of the material caused by temperature fluctuations and humidity changes in the underground environment, avoid cracks or gaps in the sublayer, and ensure the structural density of the second sublayer 22; nano-montmorillonite can improve the barrier property, delay the penetration of water vapor and chemical medium, and improve the long-term stability; the silane coupling agent can improve the compatibility of inorganic nano-materials (nano-silicon dioxide, nano-montmorillonite) and the HDPE matrix, enhance the interface bonding, ensure the uniformity and stability of the mechanical properties and barrier properties of the second sublayer 22, and improve the overall structural strength of the material; the antioxidant can inhibit the oxidation and aging of the material and prolong the service life.

[0032] Further, the third sublayer 23 includes the following raw materials in parts by weight: polyamide 12 resin 80-90 parts, n-nonanoic acid vanillyl amide 1-2 parts, FYJ-01 termite-resistant functional masterbatch 1-2 parts, and glass fiber 5-10 parts.

[0033] The polyamide 12 resin (hereinafter referred to as PA12 resin) as the core base material of the third sub-layer 23 and the termite-proof functional carrier has excellent mechanical strength, flexibility and chemical corrosion resistance. On the one hand, it can build a dense functional carrier layer to ensure that other termite-proof components and reinforcing materials are uniformly dispersed and firmly attached, avoiding the loss of functional components due to loose base material structure. On the other hand, its low water absorption and high wear resistance can adapt to complex environments such as underground humidity and corrosive media, effectively resisting soil erosion, while itself having certain anti-termite physical biting ability, forming a physical protection basis for termite prevention, and cooperating with the chemical repellent component to realize the synergistic effect of physical and chemical dual protection. In addition, the good processing fluidity and forming stability of PA12 resin can ensure that the third sub-layer 23 is closely attached to the adjacent second sub-layer 22 and fourth sub-layer 24, avoiding gaps or peeling between layers, and ensuring the overall structural integrity of the MCP composite protective layer 20. As a highly efficient and environmentally friendly termite repellent, n-valeric acid vanillamide provides the core chemical termite-proof effect for the third sub-layer 23. This component is a plant-derived repellent, which is environmentally friendly and non-toxic, and avoids the drawbacks of traditional chemical termite repellents, such as toxicity, harm and environmental pollution. It can be uniformly dispersed in the base material to avoid uneven repellent effect caused by excessive or insufficient local concentration, ensuring the comprehensiveness of termite prevention. FYJ-01 anti-termite functional masterbatch can enhance the durability and uniformity of termite prevention effect, and form a synergistic repellent system with n-valeric acid vanillamide, which enhances the repellent adaptability to different types of termites through complementary action between components, and expands the application range of termite prevention. At the same time, the masterbatch has excellent slow-release performance, which can control the release rate of n-valeric acid vanillamide, avoid its large-scale precipitation in the short term, and ensure that the third sub-layer 23 continuously and stably plays the termite-proof effect in the whole life cycle of the cable. Glass fiber as a structural reinforcing component can improve the puncture resistance, tear resistance and interlayer bonding strength of the third sub-layer 23, and strengthen the reliability of termite prevention.

[0034] Further, the fourth sub-layer 24 includes the following raw materials in parts by weight: linear low density polyethylene resin 70-80 parts, halogen-free flame retardant 15-20 parts, carbon black 2-3 parts, ultraviolet absorber 0.5-1 part, and lubricant 0.5-1 part.

[0035] The linear low-density polyethylene resin (hereinafter referred to as LLDPE resin) has excellent flexibility and environmental stress cracking resistance, which can adapt to bending, dragging and other operations during cable laying, avoid cracking and damage caused by too high material rigidity, buffer the extrusion stress of underground soil, reduce the external force impact on the inner third sublayer 23, and ensure the stability of the termite prevention function. At the same time, it has good weather resistance and chemical stability, which builds a basic protective barrier for the inner structure, and the excellent processing fluidity provides a stable carrier for the uniform dispersion of other functional additives, ensuring the uniformity of the overall performance of the fourth sublayer 24. The halogen-free flame retardant realizes environmental protection and flame retardation, meets the UL94 V-0 and IEC Cat A standards. Carbon black can play a core role in ultraviolet shielding and weather resistance enhancement, delaying material photoaging. The ultraviolet absorber can form a synergistic weathering system with carbon black, further strengthening the ultraviolet protection effect and prolonging the overall service life of the cable. The lubricant is used to improve the extrusion processing fluidity and reduce surface defects.

[0036] Further, the first compatibilizer is provided between the second sublayer 22 and the third sublayer 23, and the first compatibilizer is maleic anhydride grafted polyethylene. The third sublayer 23 can further include 2-5 parts of the first compatibilizer, and the first compatibilizer is preferably maleic anhydride grafted polyethylene (MAPE), which can improve the interfacial bonding strength of the second sublayer 22 and the third sublayer 23, and avoid the occurrence of interlayer slip and peeling.

[0037] Further, the second compatibilizer is provided between the third sublayer 23 and the fourth sublayer 24, and the second compatibilizer is maleic anhydride grafted polypropylene. The fourth sublayer 24 can further include 2-5 parts of the second compatibilizer, and the second compatibilizer is preferably maleic anhydride grafted polypropylene (MAPP), which can improve the interfacial bonding strength of the third sublayer 23 and the fourth sublayer 24, and avoid the occurrence of interlayer slip and peeling.

[0038] As a preferred embodiment, the second sub-layer 22, the third sub-layer 23 and the fourth sub-layer 24 are integrally formed by three-layer co-extrusion, that is, one-time forming by three-layer co-extrusion technology, to form a tightly bonded composite functional sheath, which can significantly improve the bonding tightness between the sub-layers, form a composite functional sheath with no interface gap and integrated structure, and further strengthen the overall synergistic protection effect of the MCP composite sheath 20. On the one hand, it can avoid the problem of loose fitting of each sub-layer, easy to introduce air or impurities, ensure the dense structure of the composite sheath, effectively block the penetration channel of water vapor and corrosive medium, and improve the long-term service stability; on the other hand, the one-time forming process greatly simplifies the production process, reduces the processing links, reduces the production energy consumption and cost, and avoids the damage to the material performance caused by multiple processing, thereby ensuring the stable play of the core functions of each sub-layer; in addition, the integrally formed composite sheath has more excellent overall mechanical properties, and when the cable is bent, dragged or impacted by external force, each sub-layer can bear stress cooperatively, avoid local stress concentration caused by interlayer slip, reduce the risk of sheath damage, and further improve the adaptability of the cable in complex underground working conditions.

[0039] As a preferred embodiment, the cable further comprises a shielding layer, which comprises a partial shielding layer 17 and a total shielding layer 18, a plurality of conductors 10 constitute an instrument cable core unit, and the outer side of a single instrument cable core unit is provided with the partial shielding layer 17, and the outer side of a twisted structure formed by a plurality of instrument cable core units is provided with the total shielding layer 18.

[0040] As shown in Figure 1 The partial shielding layer 17 and the total shielding layer 18 are both provided with a drain wire, and the shielding layer can adopt an aluminum plastic tape. During processing, the conductors 10 are twisted in pairs (single instrument cable core unit) or in groups (multiple instrument cable core units) to form a twisted structure, and then the aluminum plastic tape is wrapped around the outer layer of the cable core and the drain wire is placed. The partial shielding layer 17 and the total shielding layer 18 form double electromagnetic shielding lines at the unit level and the overall level, which can accurately resist electromagnetic interference at different levels. For example, the partial shielding layer 17 effectively isolates the internal electromagnetic interference between adjacent instrument cable core units, avoids signal transmission interference between different units, and the total shielding layer 18 comprehensively wraps the overall twisted structure formed by a plurality of instrument cable core units, efficiently blocks the invasion of electromagnetic radiation in the external environment into the cable core, and prevents the cable itself from radiating signals outward to cause leakage. By arranging the drain wire, the shielding reliability and construction safety are further improved. Of course, it can be understood that only one of the partial shielding layer 17 and the total shielding layer 18 can be arranged.

[0041] Based on the termite-resistant cable of the present application, the present application further provides a preparation method of a termite-resistant cable, the cable comprising, from inside to outside, in sequence: a conductor, an insulation layer, an inner sheath, an MCP composite sheath, an armor layer and an outer sheath, the preparation method comprising: A plurality of strands of tinned copper wire are stranded to form a conductor, an insulation layer is extruded over the conductor, and an inner sheath is extruded over the insulation layer; The MCP composite sheath is formed by sequentially including a first sublayer, a second sublayer, a third sublayer, and a fourth sublayer from inside to outside, the first sublayer adopts an aluminum-plastic composite tape, the second sublayer adopts a high-density polyethylene nanocomposite material, the third sublayer adopts an ant-termite polyamide material, and the fourth sublayer adopts a linear low-density polyethylene functional composite material, and the MCP composite sheath is formed by wrapping the first sublayer outside the inner sheath and forming the second sublayer, the third sublayer, and the fourth sublayer outside the first sublayer; An armored layer is stranded outside the MCP composite sheath, and an outer sheath is extruded outside the armored layer.

[0042] The cable can adopt the materials of the above embodiments, and details are not repeated. In the MCP composite sheath, the first sublayer adopts an aluminum-plastic composite tape, which is longitudinally wrapped or overlap-wrapped with an aluminum foil and a polyester film composite tape to provide electromagnetic shielding, an initial moisture-proof barrier, and a base support for subsequent extruded layers. The second to fourth sublayers are preferably extruded at one time by a three-layer co-extrusion process to improve structural performance and simplify the process flow. Specifically, the second, third, and fourth sublayers (i.e., HDPE / PA12 / LLDPE) can be extruded at one time by a three-layer co-extrusion head to be wrapped outside the aluminum-plastic tape. The HDPE layer can be extruded at a temperature of about 190°C to ensure sufficient melting and good fluidity, avoiding degradation; the PA12 layer can be extruded at a temperature of about 230°C to facilitate uniform dispersion of functional additives and not affect the stability of the ant-termite component; and the LLDPE layer can be extruded at a temperature of about 200°C to ensure sufficient melting and not affect the surface quality. The head temperature can be set to about 220°C, which is slightly higher than the melting temperature of each layer, to ensure that the three-layer melt is well fused and closely combined in the head, avoiding delamination. Specifically, a multi-temperature zone independent temperature control extrusion system can be used, each layer of material is equipped with an independent heating and temperature control module, the temperature of each layer is monitored and adjusted in real time to ensure stable melt temperature and uniform interlayer bonding. Further, a circulating water cooling system is used to rapidly cool and set the extruded sheath after co-extrusion, avoiding interlayer displacement, deformation, or uneven material crystallization. The cooling water temperature can be set to 20-30°C to avoid insufficient cooling caused by excessively high water temperature, resulting in structural relaxation, or excessively low water temperature causing rapid material shrinkage and stress concentration, ensuring stable size, firm interlayer bonding, and smooth surface of the composite sheath. The extrusion line speed can be set to 60-100 m / min, which can be flexibly adjusted according to the material fluidity, cooling efficiency, and equipment capacity to avoid insufficient cooling and uneven thickness caused by excessively high speed, or low production capacity caused by excessively low speed, ensuring efficient and continuous production under the premise of ensuring interlayer bonding quality and appearance.

[0043] The structure and preparation process of the termite-proof cable are described below in combination with specific examples.

[0044] Example 1: The cable comprises, from inside to outside, in sequence: Conductor: multiple strands of tin-plated copper wire twisted together; Insulating layer: cross-linked polyethylene (XLPE); Shielding layer: aluminum plastic tape shielding layer wrapping + drainage wire; Inner sheath: low-smoke halogen-free flame-retardant polyolefin (LSZH); MCP composite sheath: First sub-layer: aluminum plastic composite tape (Al / PET), thickness 0.05 mm, wrapping overlap rate ≥ 25%; Second sub-layer (inner layer): HDPE nanocomposite material, components (by weight): HDPE resin 90 parts, nano-silicon dioxide 3 parts, nano-montmorillonite 2 parts, silane coupling agent 0.7 parts, antioxidant 0.3 parts; Third sub-layer (middle layer): termite-resistant polyamide material, components (by weight): PA12 resin 85 parts, n-nonanoic acid vanillyl amide 1.5 parts, FYJ-01 anti-termite functional masterbatch 1.5 parts, glass fiber 8 parts, maleic anhydride grafted polyethylene (MAPE) compatibilizer 3 parts; Fourth sub-layer (outer layer): LLDPE functional composite material, components (by weight): LLDPE resin 75 parts, halogen-free flame retardant 18 parts, carbon black 2.5 parts, ultraviolet absorber 0.7 parts, lubricant 0.8 parts, maleic anhydride grafted polypropylene (MAPP) compatibilizer 3 parts; Armoring layer: galvanized steel wire armor (GSWA); Outer sheath: black low-smoke halogen-free flame-retardant polyolefin (LSZH).

[0045] The preparation method of the cable comprises the following steps: Conductor twisting: twisting multiple strands of tin-plated copper wire into a conductor; Insulating layer extrusion: extruding an XLPE insulating layer outside the conductor; Shielding layer wrapping: wrapping an aluminum plastic tape outside the insulating layer and placing a drainage wire; Inner sheath extrusion: extruding an LSZH inner sheath outside the shielding layer; MCP composite sheath forming: First, wrap the aluminum plastic composite tape (Al / PET); Then, through a three-layer co-extrusion head, extrude an HDPE / PA12 / LLDPE three-layer sheath outside the aluminum plastic tape at one time; Co-extrusion process parameters: HDPE layer temperature: 190℃; PA12 layer temperature: 230℃; LLDPE layer temperature: 200℃; Die temperature: 220℃; Cooling water temperature: 25℃; Linear speed: 80 m / min; Armoring layer stranding: Stranding galvanized steel wire armor outside MCP composite sheath; Outer sheath extrusion: Extruding black LSZH outer sheath outside the armoring layer.

[0046] Example 2: The cable comprises, from inside to outside, in order: Conductor: Stranding of multiple copper wires; Insulating layer: Cross-linked polyethylene (XLPE); Inner sheath: Low-smoke halogen-free flame-retardant polyolefin (LSZH); MCP composite sheath: First sub-layer: Aluminum-plastic composite tape (Al / PET), thickness 0.04mm, wrapping overlap rate ≥30%; Second sub-layer (inner layer): HDPE nanocomposite material, components (weight parts): HDPE resin 85 parts, nano-silicon dioxide 5 parts, nano-montmorillonite 3 parts, silane coupling agent 1 part, antioxidant 0.5 parts; Third sub-layer (middle layer): Ant termite polyamide material, components (weight parts): PA12 resin 80 parts, n-nonanoic acid vanillyl amide 2 parts, FYJ-01 anti-termite functional masterbatch 2 parts, glass fiber 10 parts, maleic anhydride grafted polyethylene (MAPE) compatibilizer 5 parts; Fourth sub-layer (outer layer): LLDPE functional composite material, components (weight parts): LLDPE resin 70 parts, halogen-free flame retardant 20 parts, carbon black 3 parts, ultraviolet absorber 1 part, lubricant 1 part, maleic anhydride grafted polypropylene (MAPP) compatibilizer 5 parts; Armoring layer: Galvanized steel wire armor (GSWA); Outer sheath: Black low-smoke halogen-free flame-retardant polyolefin (LSZH).

[0047] The method for preparing the cable comprises the following steps: Conductor stranding: Stranding multiple copper wires into a conductor; Insulating layer extrusion: Extruding an XLPE insulating layer outside the conductor; Inner sheath extrusion: Extruding an LSZH inner sheath outside the insulating layer; MCP composite sheath forming: First, wrapping the aluminum-plastic composite tape (Al / PET); Then, extruding an HDPE / PA12 / LLDPE three-layer sheath outside the aluminum-plastic tape through a three-layer co-extrusion die; Co-extrusion process parameters: HDPE layer temperature: 180℃; PA12 layer temperature: 220℃; LLDPE layer temperature: 190℃; Die temperature: 210℃; Cooling water temperature: 20℃; Linear speed: 60 m / min; Armoring layer stranding: Stranding galvanized steel wire armor outside MCP composite sheath; Outer sheath extrusion: Extruding black LSZH outer sheath outside the armoring layer.

[0048] Example 3: The cable comprises, from inside to outside, in order: Conductor: Stranding of multiple tinned copper wires; Insulation layer: Cross-linked polyethylene (XLPE); Shielding layer: Aluminum-plastic tape total shielding layer wrapping + drain wire; Inner sheath: Low-smoke halogen-free flame-retardant polyolefin (LSZH); MCP composite sheath: First sub-layer: Aluminum-plastic composite tape (Al / PET), thickness 0.06mm, wrapping overlap rate ≥20%; Second sub-layer (inner layer): HDPE nanocomposite material, components (weight parts): HDPE resin 95 parts, nano-silicon dioxide 2 parts, nano-montmorillonite 1 part, silane coupling agent 0.5 parts, antioxidant 0.3 parts; Third sub-layer (middle layer): Ant termite polyamide material, components (weight parts): PA12 resin 90 parts, n-nonanoic acid vanillyl amide 1 part, FYJ-01 anti-termite functional masterbatch 1 part, glass fiber 5 parts, maleic anhydride grafted polyethylene (MAPE) compatibilizer 2 parts; Fourth sub-layer (outer layer): LLDPE functional composite material, components (weight parts): LLDPE resin 80 parts, halogen-free flame retardant 15 parts, carbon black 2 parts, ultraviolet absorber 0.5 parts, lubricant 0.5 parts, maleic anhydride grafted polypropylene (MAPP) compatibilizer 2 parts; Armoring layer: Galvanized steel wire armor (GSWA); Outer sheath: Black low-smoke halogen-free flame-retardant polyolefin (LSZH).

[0049] The method for preparing the cable comprises the following steps: Conductor stranding: Stranding multiple tinned copper wires into a conductor; Insulation layer extrusion: Extruding an XLPE insulation layer outside the conductor; Shielding layer wrapping: Wrapping an aluminum-plastic tape total shielding layer outside the insulation layer and placing a drain wire; Inner sheath extrusion: Extruding an LSZH inner sheath outside the shielding layer; MCP composite sheath forming: Firstly, the aluminum-plastic composite tape (Al / PET) is wound; Then, the HDPE / PA12 / LLDPE three-layer sheath is extruded by a three-layer co-extrusion head to cover the aluminum-plastic tape; The co-extrusion process parameters are as follows: The temperature of the HDPE layer is 200°C, the temperature of the PA12 layer is 240°C, the temperature of the LLDPE layer is 210°C, and the temperature of the head is 230°C; The cooling water temperature is 30°C, and the linear speed is 100 m / min; The armored layer is twisted: galvanized steel wire armor is twisted outside the MCP composite sheath; The outer sheath is extruded: a black LSZH outer sheath is extruded outside the armored layer.

[0050] Comparative Example 1: The traditional lead sheath cable is used, and the structure from the inside to the outside includes a conductor, an insulation layer, a lead sheath layer, and an outer sheath layer.

[0051] Table 1: Comparison of cable performance indicators of each example and comparative example Performance Index Example 1 Example 2 Example 3 Comparative Example 1 Termite Resistance (Nest Method) Grade 1 Grade 1 Grade 1 Grade 1 Environmental Friendliness Good (Lead-free) Good (Lead-free) Good (Lead-free) Poor (Lead-containing) Relative Weight 0.5 0.45 0.55 1 Flexibility (Relative Value) 1.5 1.6 1.4 1 Flame Retardant Grade UL94 V-0 / IEC Cat A UL94 V-0 / IEC Cat A UL94 V-0 / IEC Cat A UL94 V-2 Ultraviolet Resistance Good Good Good Medium Chemical Corrosion Resistance Good Good Good Medium Service Life (Years) 30 35 25 25 Production Efficiency (Relative Value) 1.4 1.5 1.3 1 Overall Cost (Relative Value) 0.75 0.7 0.8 1 Table 1 lists the performance indicators of the cables of each example and comparative example. As can be seen from Table 1, the cable of the present application completely eliminates lead pollution, meets modern environmental protection requirements and regulatory standards; the termite prevention effect is remarkable: through the dual action of physical barrier and chemical repellent, the termite prevention effect equivalent to lead sheath is achieved, and the ant nest method test reaches level 1 of the termite corrosion grade; the comprehensive performance is improved: while maintaining the termite prevention performance, the flexibility, weather resistance, and service life of the cable are significantly improved; the economic benefit is obvious: the production efficiency is improved by 30-50%, and the comprehensive cost is reduced by 20-30%; the production process is simplified: one-step molding is adopted by using three-layer co-extrusion technology, which simplifies the production process and improves the production efficiency; the material interface bonding strength is high: through compatibility agent optimization and process parameter control, the close combination between layers is ensured; the flame retardant performance is excellent: it reaches the UL94 V-0 level flame retardant standard; the service life is long: under normal use conditions, the service life can reach 25-35 years.

[0052] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent substitutions for part of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A termite-proof cable, characterized in that, From the inside out, it includes: conductor, insulation layer, inner sheath, MCP composite sheath, armor layer and outer sheath; The MCP composite protective layer comprises, from the inside out, a first sub-layer, a second sub-layer, a third sub-layer, and a fourth sub-layer. The first sub-layer is made of aluminum-plastic composite tape, the second sub-layer is made of high-density polyethylene nanocomposite material, the third sub-layer is made of termite-resistant polyamide material, and the fourth sub-layer is made of linear low-density polyethylene functional composite material.

2. The termite-proof cable according to claim 1, characterized in that, The second sublayer comprises the following raw materials in parts by weight: 85-95 parts high-density polyethylene resin, 2-5 parts nano silica, 1-3 parts nano montmorillonite, 0.5-1 part silane coupling agent, and 0.3-0.5 parts antioxidant.

3. The termite-proof cable according to claim 2, characterized in that, The third sublayer comprises the following raw materials in parts by weight: 80-90 parts of polyamide 12 resin, 1-2 parts of n-nonanoic acid vanillamide, 1-2 parts of FYJ-01 anti-termite functional masterbatch, and 5-10 parts of glass fiber.

4. The termite-proof cable according to claim 3, characterized in that, The fourth sublayer comprises the following raw materials in parts by weight: 70-80 parts linear low-density polyethylene resin, 15-20 parts halogen-free flame retardant, 2-3 parts carbon black, 0.5-1 part ultraviolet absorber, and 0.5-1 part lubricant.

5. The termite-proof cable according to claim 1, characterized in that, The second sublayer, the third sublayer, and the fourth sublayer are integrally formed by three-layer co-extrusion.

6. The termite-proof cable according to claim 3, characterized in that, A first compatibilizer, which is maleic anhydride-grafted polyethylene, is provided between the second sublayer and the third sublayer.

7. The termite-proof cable according to claim 4, characterized in that, A second compatibilizer, which is maleic anhydride-grafted polypropylene, is provided between the third sublayer and the fourth sublayer.

8. The termite-proof cable according to any one of claims 1-7, characterized in that, Both the inner and outer sheaths are made of low-smoke, halogen-free, flame-retardant polyolefin material, and the armor layer is made of galvanized steel wire armor.

9. The termite-proof cable according to any one of claims 1-7, characterized in that, It also includes a shielding layer, which includes a sub-shielding layer and a total shielding layer. Multiple conductors constitute an instrument cable core unit. The sub-shielding layer is provided on the outside of a single instrument cable core unit, and the total shielding layer is provided on the outside of the stranded structure composed of multiple instrument cable core units.

10. A method for preparing a termite-proof cable, characterized in that, The cable, from the inside out, comprises: a conductor, an insulation layer, an inner sheath, an MCP composite sheath, an armor layer, and an outer sheath. The manufacturing method includes: Multiple strands of tin-plated copper wire are twisted into a conductor, an insulating layer is extruded on the outside of the conductor, and an inner sheath is extruded on the outside of the insulating layer. MCP composite sheath molding, wherein the MCP composite sheath comprises, from the inside out, a first sub-layer, a second sub-layer, a third sub-layer, and a fourth sub-layer, wherein the first sub-layer is made of aluminum-plastic composite tape, the second sub-layer is made of high-density polyethylene nanocomposite material, the third sub-layer is made of termite-resistant polyamide material, and the fourth sub-layer is made of linear low-density polyethylene functional composite material, wherein the MCP composite sheath molding includes: wrapping the first sub-layer around the outside of the inner sheath, and forming the second sub-layer, the third sub-layer, and the fourth sub-layer on the outside of the first sub-layer; An armor layer is formed by twisting the outer side of the MCP composite sheath, and an outer sheath is extruded on the outer side of the armor layer.

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