Crosslinked polyethylene power cable and preparation method thereof

Abstract

The invention relates to the technical field, and particularly discloses a crosslinked polyethylene power cable and a preparation method thereof. The cross-linked polyethylene power cable is prepared from the following raw materials in parts by weight: 45 to 55 parts of ethylene-vinyl acetate copolymer, 2 to 4 parts of modified nanoparticle filler, 30 to 40 parts of low-density polyethylene, 5 to 10 parts of polycaprolactone, 3 to 5 parts of modified montmorillonite, 8 to 12 parts of ethylene-methyl acrylate copolymer, 3 to 5 parts of phenyl silicone oil, 1.5 to 2.0 parts of cross-linking agent and 0.5 to 0.9 part of antioxidant. And 1.5 to 2.5 parts of a triazine derivative. The crosslinked polyethylene power cable can be used for power transmission systems, industrial power distribution networks, urban power grid construction and other scenes, and has the advantages of high mechanical performance and good aging resistance.

Description

Technical Field

[0001] This invention relates to the field of cable manufacturing, and in particular to a cross-linked polyethylene power cable and its preparation method. Background Technology

[0002] In the field of power transmission, the development of cross-linked polyethylene (XLPE) power cables is crucial. With the continuous growth of electricity demand and the increasing demands for stability and safety in power systems, XLPE power cables, as key components in power transmission, directly impact the operational efficiency and reliability of the entire power system. High-quality XLPE power cables can effectively reduce energy loss, lower the failure rate, and ensure a stable power supply, playing an irreplaceable role in various fields such as industrial production and residential life.

[0003] In the traditional production of cross-linked polyethylene (XLPE) power cables, a relatively conventional combination of raw materials is typically used. The common practice is to use polyethylene as the main matrix material and then add some conventional additives to improve cable performance. Some cables will have ordinary inorganic fillers added to enhance their mechanical properties, and antioxidants added to prevent oxidation during long-term use. These conventional methods can meet basic power transmission requirements to a certain extent, but their performance has certain limitations in different application scenarios.

[0004] Traditional cross-linked polyethylene (XLPE) power cables have significant drawbacks due to their conventional raw material combinations. Cables made from conventional raw materials often fail to meet ideal overall performance requirements in terms of mechanical properties and oxidation resistance. These cables may experience a decline in mechanical properties over long-term use, thus affecting their lifespan and the stability of power transmission. Summary of the Invention

[0005] To address the aforementioned problems, this application provides a cross-linked polyethylene power cable and a method for its preparation.

[0006] In a first aspect, this application provides a cross-linked polyethylene power cable, which adopts the following technical solution: A cross-linked polyethylene power cable comprises the following raw materials in parts by weight: 45-55 parts of ethylene-vinyl acetate copolymer, 2-4 parts of modified nanoparticle filler, 30-40 parts of low-density polyethylene, 5-10 parts of polycaprolactone, 3-5 parts of modified montmorillonite, 8-12 parts of ethylene-methyl acrylate copolymer, 3-5 parts of phenyl silicone oil, 1.5-2.0 parts of crosslinking agent, 0.5-0.9 parts of antioxidant, and 1.5-2.5 parts of triazine derivative.

[0007] By employing the above technical solutions, the crosslinking agent triggers crosslinking reactions between vinyl polymer molecular chains under specific process conditions, forming a dense three-dimensional network structure, significantly improving the material's thermal stability and tensile deformation resistance. Modified nanoparticle fillers and modified montmorillonite form a physical barrier through nanoscale dispersion and layered intercalation structures, synergistically enhancing the material's mechanical strength and high-temperature dielectric properties. Polycaprolactone optimizes the interfacial bonding of polar / non-polar components through molecular chain entanglement, eliminating phase separation defects. Ethylene-methyl acrylate copolymer improves the system's processing fluidity, reduces melt viscosity, and balances internal stress distribution through the introduction of flexible segments. Phenyl silicone oil, with its unique siloxane structure, simultaneously performs internal lubrication and interfacial modification functions, promoting uniform filler dispersion and reducing frictional losses during extrusion. Triazine derivatives, as electrical stabilizers, suppress partial discharge under high field strength through electron capture mechanisms, delaying the electrical aging process of the insulation layer. Antioxidants block the thermo-oxidative degradation chain reaction through free radical quenching, forming a multi-protection system. Ultimately, the material maintains excellent dimensional stability and resistance to environmental cracking under high-temperature service environments, significantly improving the long-term operational reliability of the cable.

[0008] Optionally, the modified nanoparticle filler is prepared by the following method: (1) Disperse silica nanoparticles in an ethanol solution, add vinyltrimethoxysilane, react at 75-85℃ for 2.5-3.5h, centrifuge, wash and dry to obtain the product for later use; (2) Dissolve octavinylsilsesquioxane and azobisisobutyronitrile in toluene and add them to the product of step (1). After reacting at 80-90℃ for 1.5-2.5h under nitrogen protection, cool down to 65-75℃ and then add γ-aminopropyltriethoxysilane. React for 1-2h, precipitate, centrifuge, wash and dry to obtain the modified nanoparticle filler.

[0009] By employing the above technical solution, firstly, vinyltrimethoxysilane undergoes a hydrolysis-condensation reaction with the hydroxyl groups on the surface of silica nanoparticles, introducing active double bond groups onto the particle surface to form an organic-inorganic hybrid interface layer. Secondly, through a free radical polymerization reaction initiated by azobisisobutyronitrile, octavinylsilsesquioxane is grafted onto the particle surface to construct a cage-like nanostructure. Its polyvinyl properties enhance the physical entanglement with the polymer matrix. Subsequently, γ-aminopropyltriethoxysilane is introduced to form a three-dimensional gradient transition layer on the nanoparticle surface through the polar interaction between the amino group and the polymer chain, as well as secondary crosslinking points formed by the hydrolysis of siloxane. This hierarchical structural modification endows the filler with both the high rigidity and heat resistance of inorganic nanoparticles and the flexibility and compatibility of organic components, significantly improving its dispersion uniformity and interfacial bonding strength in the polyethylene matrix. At the same time, the cavity structure of the cage-like silsesquioxane can effectively capture and dissipate electric field energy, inhibiting space charge accumulation. Combined with the partial discharge self-healing function of the amino group, this ultimately endows the cable material with excellent mechanical reinforcement and anti-electro-aging properties.

[0010] Optionally, the mass ratio of silicon dioxide to vinyltrimethoxysilane is 1:0.17-0.25; the mass ratio of silicon dioxide to octavinylsilsesquioxane is 1:0.17-0.21. The mass ratio of silicon dioxide to γ-aminopropyltriethoxysilane is 1:0.09-0.11.

[0011] By employing the above technical solutions, vinyltrimethoxysilane reacts with hydroxyl groups on the surface of silica in an appropriate ratio to form a dense monomolecular modification layer on the particle surface, ensuring both the high rigidity of the inorganic core and introducing active vinyl anchors; octavinylsilsesquioxane is grafted in a specific ratio to construct cage-like nano-reinforcing units, whose multi-arm structure can form a physical entanglement network with polyethylene chains, while the cage-like cavity effectively disperses electric field stress; γ-aminopropyltriethoxysilane is used for surface finishing in an optimized ratio, where its amino groups form hydrogen bonds with the polar groups of polyethylene, and the siloxane hydrolysis products further undergo chemical cross-linking with the matrix. The triple modifiers synergistically construct a gradient transition layer from the nano-core to the polymer interface, significantly improving the mechanical retention rate of the material under high-temperature conditions, while greatly delaying the insulation aging process through stress dispersion and charge trapping mechanisms.

[0012] Optionally, the modified montmorillonite is hexadecyltrimethylammonium bromide intercalated montmorillonite, and its preparation includes the following steps: Sodium-based montmorillonite was dispersed in deionized water, and hexadecyltrimethylammonium bromide was added. The mixture was stirred at 75-85°C for 4 hours, and after washing and drying, the modified montmorillonite was obtained.

[0013] By employing the above technical solution, modified montmorillonite achieves dual optimization of structure and performance through ion-exchange intercalation of sodium-based montmorillonite with hexadecyltrimethylammonium bromide. Long-chain alkyl quaternary ammonium salt molecules are embedded into the interlayer of montmorillonite via cation exchange, and their hydrophobic carbon chains transform the hydrophilic layered structure into organic-inorganic composite nanosheets, significantly increasing the interlayer spacing and enhancing compatibility with the polyethylene matrix. The intercalated montmorillonite sheets form a physical barrier network in the matrix, effectively suppressing the initiation and propagation of electrical trees. Simultaneously, their high aspect ratio structure disperses electric field stress concentration. The polar head groups of the quaternary ammonium salt generate dipole-induced dipole interactions with the polyethylene chains, further strengthening the interfacial bonding strength. This intercalation modification endows montmorillonite with both the reinforcing effect of inorganic fillers and the flexibility of organic components, significantly improving the material's breakdown field strength and high-temperature stability. Furthermore, the sheet barrier effect inhibits oxygen and moisture penetration, greatly extending the service life of cables in harsh environments.

[0014] Optionally, the mass ratio of sodium montmorillonite to cetyltrimethylammonium bromide is 1:0.32-0.36.

[0015] By adopting the above technical solution, an appropriate amount of quaternary ammonium salt molecules are fully embedded in the interlayer of montmorillonite through ion exchange. The long-chain alkyl groups form an ordered hydrophobic barrier in the interlayer, which not only effectively expands the interlayer spacing to enhance compatibility with the polyethylene matrix, but also avoids interface defects caused by excessive organic matter, thus obtaining the best modification effect.

[0016] Optionally, the triazine derivative is 2,4,6-triamino-1,3,5-triazine.

[0017] By employing the above technical solution, leveraging its highly conjugated triazine ring structure and amino electron donor characteristics, a multiple voltage stabilization mechanism is formed within the polyethylene matrix: the conjugated system effectively captures high-energy electrons and rapidly dissipates their energy, suppressing insulation breakdown caused by electron collisions; the amino groups form a dynamic cross-linked network with the polyethylene chains through hydrogen bonding, enhancing local structural stability and dispersing electric field stress concentration; its unique molecular structure also allows for reversible redox reactions in the ozone and free radical environment generated by corona discharge, repairing micro-damage to the insulation layer. This synergistic effect significantly enhances the breakdown field strength of the material under high-voltage electric fields, while simultaneously significantly delaying the insulation aging process by suppressing partial discharge and electrical treeing, ensuring the safety and reliability of the cable during long-term high-load operation.

[0018] Optionally, 0.8-1.2 parts of zinc stearate are also added to the raw materials.

[0019] By adopting the above technical solutions, the fatty acid groups of zinc stearate form a dynamic lubricating layer on the surface of modified nanoparticle fillers and modified montmorillonite through physical adsorption and polar interaction, which significantly reduces the tendency of filler agglomeration and improves dispersion uniformity. At the same time, the weak interaction with polyethylene chains can act as sacrificial bonds to dissipate stress energy. Zinc ions form a synergistic protective network with triazine derivatives and antioxidants through coordination, which enhances the capture efficiency of high-energy electrons and free radicals. During processing, zinc stearate migrates to the melt-metal interface to form a lubricating film, which effectively reduces melt fracture caused by extrusion friction and reduces surface defects. Through multi-party synergy, the mechanical properties and long-term thermal aging stability of the product are further improved.

[0020] Secondly, this application provides a method for preparing a cross-linked polyethylene power cable, employing the following technical solution: A method for preparing a cross-linked polyethylene power cable includes the following steps: Ethylene-vinyl acetate copolymer, low-density polyethylene, and polycaprolactone are mixed at 100-110℃ for 3-5 min. Modified montmorillonite, ethylene-methyl acrylate copolymer, phenyl silicone oil, modified nanoparticle filler, and triazine derivative are added. The mixture is sheared and dispersed at 110-130℃ at a rate of 2500 rpm for 15-20 min. After cooling to 80-90℃, crosslinking agent and antioxidant are added, mixed, and then extruded. The mixture is crosslinked in a steam vulcanization pipe at 170-180℃ for 20-30 min. After cooling to room temperature, the target product is obtained.

[0021] In summary, this application has the following beneficial effects: 1. The nanoparticle filler in this application combines the high rigidity and heat resistance of inorganic nanoparticles. Through nanoscale dispersion, it forms a good interfacial bond with the polyethylene matrix. The polyvinyl properties of its cage-like nanostructure can enhance the physical entanglement with the polymer matrix, effectively improving the tensile deformation resistance and mechanical strength of the material. Modified montmorillonite, as an inorganic filler, forms a reinforcing network in the matrix with its layered structure, further improving the hardness and strength of the material.

[0022] 2. The nanoparticle filler and modified montmorillonite in this application work synergistically with polycaprolactone as a compatibilizer to optimize the interfacial bonding of polar / non-polar components, eliminate phase separation defects, and form a dense three-dimensional network structure and good interfacial bonding through the interaction between the raw materials. This effectively resists environmental stress cracking and improves the service life of the cable in harsh environments. Detailed Implementation

[0023] The following detailed description of this application is provided in conjunction with the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available sources.

[0024] Ethylene-vinyl acetate copolymer (EVA450) was purchased from Shanghai Liangrun International Trade Co., Ltd.; low-density polyethylene (LDPE) was purchased from Suzhou Huasulian Plastics Technology Co., Ltd. (FD0270); silica nanoparticles (particle size range 20-50 nm); polycaprolactone (PCL) was purchased from Wuhan Kemike Biomedical Technology Co., Ltd. (CAS No. 24980-41-4); and ethylene-methyl acrylate copolymer (20MA08) was purchased from Dongguan Shangpin New Material Technology Co., Ltd.

[0025] Preparation examples of raw materials and / or intermediates Preparation Example 1 A modified nanoparticle filler is prepared by the following steps: (1) Weigh 10 kg of silica nanoparticles and disperse them in a 90% volume fraction ethanol solution to form a suspension with a solid content of 10%. Add 2.1 kg of vinyltrimethoxysilane while stirring at 300 rpm. Heat the system to 80°C and keep it at that temperature for 3 h. After centrifugation, collect the precipitate, wash and dry it to obtain the product for later use. (2) 1.9 kg of octavinylsilsesquioxane and 0.07 kg of azobisisobutyronitrile were added to toluene and stirred to dissolve. Then, the mixture was added to the product of step (1) and mixed evenly. Nitrogen gas was introduced and the reaction system was heated to 85°C and kept at that temperature for 2 hours. After the initial reaction was completed, the system temperature was lowered to 70°C and 1 kg of γ-aminopropyltriethoxysilane was added to continue the reaction for 1.5 hours. After the reaction was completed, the mixture was cooled to room temperature, precipitated, centrifuged, washed, and dried to obtain the modified nanoparticle filler.

[0026] Preparation Example 2 A modified nanoparticle filler is prepared by the following steps: (1) Weigh 10 kg of silica nanoparticles and disperse them in a 90% volume fraction ethanol solution to form a suspension with a solid content of 10%. Add 1.7 kg of vinyltrimethoxysilane while stirring at 300 rpm. Heat the system to 75°C and keep it at that temperature for 3.5 h. After centrifugation, collect the precipitate, wash and dry it to obtain the product for later use. (2) 1.7 kg of octavinylsilsesquioxane and 0.06 kg of azobisisobutyronitrile were added to toluene and stirred to dissolve. Then, the mixture was added to the product of step (1) and mixed evenly. Nitrogen gas was introduced and the reaction system was heated to 80°C and kept at that temperature for 2.5 h. After the initial reaction was completed, the system temperature was lowered to 70°C and 0.9 kg of γ-aminopropyltriethoxysilane was added to continue the reaction for 2 h. After the reaction was completed, the mixture was cooled to room temperature, precipitated, centrifuged, washed and dried to obtain the modified nanoparticle filler.

[0027] Preparation Example 3 A modified nanoparticle filler is prepared by the following steps: (1) Weigh 10 kg of silica nanoparticles and disperse them in a 90% volume fraction ethanol solution to form a suspension with a solid content of 10%. Add 2.5 kg of vinyltrimethoxysilane while stirring at 300 rpm. Heat the system to 85°C and keep it at that temperature for 2.5 h. After centrifugation, collect the precipitate, wash and dry it to obtain the product for later use. (2) 2.1 kg of octavinylsilsesquioxane and 0.08 kg of azobisisobutyronitrile were added to toluene and stirred to dissolve. Then, the mixture was added to the product of step (1) and mixed evenly. Nitrogen gas was introduced and the reaction system was heated to 90°C and kept at that temperature for 1.5 h. After the initial reaction was completed, the system temperature was lowered to 75°C and 1.1 kg of γ-aminopropyltriethoxysilane was added to continue the reaction for 1 h. After the reaction was completed, the mixture was cooled to room temperature, precipitated, centrifuged, washed, and dried to obtain the modified nanoparticle filler.

[0028] Preparation example of modified montmorillonite Preparation Example 4 A modified montmorillonite, prepared by the following steps: 10 kg of sodium montmorillonite was dispersed in 200 L of deionized water and stirred at 500 rpm for 30 min to form a suspension. The temperature was raised to 80 °C and 3.4 kg of cetyltrimethylammonium bromide was added. The mixture was stirred and reacted for 4 h. After centrifugation, washing with 80% ethanol, vacuum drying at 80 °C, and passing through a 325 mesh sieve, the modified montmorillonite was obtained.

[0029] Preparation Example 5 A modified montmorillonite, prepared by the following steps: 10 kg of sodium montmorillonite was dispersed in 200 L of deionized water and stirred at 500 rpm for 30 min to form a suspension. The temperature was raised to 75 °C and 3.2 kg of cetyltrimethylammonium bromide was added. The mixture was stirred and reacted for 3.5 h. After centrifugation, washing with 80% ethanol, vacuum drying at 80 °C, and passing through a 325 mesh sieve, the modified montmorillonite was obtained.

[0030] Preparation Example 6 A modified montmorillonite, prepared by the following steps: 10 kg of sodium montmorillonite was dispersed in 200 L of deionized water and stirred at 500 rpm for 30 min to form a suspension. The temperature was raised to 85 °C and 3.6 kg of cetyltrimethylammonium bromide was added. The mixture was stirred and reacted for 3 h. After centrifugation, washing with 80% ethanol, vacuum drying at 80 °C, and passing through a 325 mesh sieve, the modified montmorillonite was obtained. Example

[0031] Example 1 A cross-linked polyethylene power cable is prepared by the following steps: 50 kg of ethylene-vinyl acetate copolymer, 35 kg of low-density polyethylene, and 8 kg of polycaprolactone were mixed at 105 °C for 5 min. Then, 4 kg of modified montmorillonite prepared in Preparation Example 3, 10 kg of ethylene-methyl acrylate copolymer, 4 kg of phenyl silicone oil, 3 kg of modified nanoparticle filler prepared in Preparation Example 1, and 2 kg of 2,4,6-triamino-1,3,5-triazine (triazine derivative) were added. The mixture was sheared and dispersed at 120 °C at a rate of 2500 rpm for 18 min. The sheared and dispersed material was then cooled to 85 °C. Then, 1.7 kg of dicumyl peroxide (crosslinking agent) and 0.7 kg of 2,6-di-tert-butyl-4-methylphenol (antioxidant) were added and mixed for 5 min before extrusion at 150 °C. After extrusion, the formed cable was crosslinked in a steam vulcanization pipe at 175 °C for 25 min. After cooling to room temperature, the cable was obtained.

[0032] Example 2 A cross-linked polyethylene power cable is prepared by the following steps: 45 kg of ethylene-vinyl acetate copolymer, 40 kg of low-density polyethylene, and 10 kg of polycaprolactone were mixed at 100°C for 5 min. Then, 5 kg of modified montmorillonite prepared in Preparation Example 4, 8 kg of ethylene-methyl acrylate copolymer, 5 kg of phenyl silicone oil, 4 kg of modified nanoparticle filler prepared in Preparation Example 1, and 1.5 kg of 2,4,6-triamino-1,3,5-triazine (triazine derivative) were added. The mixture was sheared and dispersed at 110°C and 2500 rpm for 20 min. The dispersed material was then cooled to 80°C, and 1.5 kg of dicumyl peroxide (crosslinking agent) and 0.9 kg of 2,6-di-tert-butyl-4-methylphenol (antioxidant) were added and mixed for 5 min before extrusion at 150°C. After extrusion, the formed cable was crosslinked in a steam vulcanization pipe at 170°C for 30 min. The cable was then removed and cooled to room temperature.

[0033] Example 3 A cross-linked polyethylene power cable is prepared by the following steps: 55 kg of ethylene-vinyl acetate copolymer, 30 kg of low-density polyethylene, and 5 kg of polycaprolactone were mixed at 110 °C for 3 min. Then, 3 kg of modified montmorillonite prepared in Preparation Example 5, 12 kg of ethylene-methyl acrylate copolymer, 3 kg of phenyl silicone oil, 2 kg of modified nanoparticle filler prepared in Preparation Example 1, and 2.5 kg of 2,4,6-triamino-1,3,5-triazine (triazine derivative) were added. The mixture was sheared and dispersed at 130 °C at a rate of 2500 rpm for 15 min. The sheared and dispersed material was then cooled to 90 °C. Then, 2 kg of dicumyl peroxide (crosslinking agent) and 0.5 kg of 2,6-di-tert-butyl-4-methylphenol (antioxidant) were added and mixed for 5 min before extrusion at 150 °C. After extrusion, the formed cable was crosslinked in a steam vulcanization pipe at 180 °C for 20 min. After cooling to room temperature, the cable was obtained.

[0034] Example 4 A cross-linked polyethylene power cable, which differs from Example 1 in that the modified nanoparticle filler used in this example is the modified nanoparticle filler prepared in Preparation Example 2.

[0035] Example 5 A cross-linked polyethylene power cable, which differs from Example 1 in that the modified nanoparticle filler used in this example is the modified nanoparticle filler prepared in Preparation Example 3.

[0036] Example 6 A cross-linked polyethylene power cable, differing from Example 1 in that 1 kg of zinc stearate is added to the raw materials in this example, specifically including the following steps: 50 kg of ethylene-vinyl acetate copolymer, 35 kg of low-density polyethylene, and 8 kg of polycaprolactone were mixed at 105 °C for 5 min. Then, 4 kg of modified montmorillonite prepared in Preparation Example 3, 10 kg of ethylene-methyl acrylate copolymer, 4 kg of phenyl silicone oil, 3 kg of modified nanoparticle filler prepared in Preparation Example 1, and 2 kg of 2,4,6-triamino-1,3,5-triazine (triazine derivative) were added. The mixture was sheared and dispersed at 120 °C at a rate of 2500 rpm for 18 min. The dispersed material was then cooled to 85 °C. Then, 1.7 kg of dicumyl peroxide (crosslinking agent), 0.7 kg of 2,6-di-tert-butyl-4-methylphenol (antioxidant), and 1 kg of zinc stearate were added and mixed for 5 min before extrusion at 150 °C. After extrusion, the formed cable was crosslinked in a steam vulcanization pipe at 175 °C for 25 min. After cooling to room temperature, the cable was obtained.

[0037] Example 7 A cross-linked polyethylene power cable, which differs from Example 1 in that 0.8 kg of zinc stearate is added to the raw materials in this example.

[0038] Example 8 A cross-linked polyethylene power cable, which differs from Example 1 in that 1.2 kg of zinc stearate is added to the raw materials in this example.

[0039] Comparative Example Comparative Example 1 A cross-linked polyethylene power cable differs from Example 1 in that an equal amount of silica nanoparticles are used instead of modified nanoparticle fillers in this comparative example.

[0040] Comparative Example 2 A cross-linked polyethylene power cable, which differs from Example 1 in that no unmodified sodium montmorillonite was added in this comparative example.

[0041] Performance testing Test method / test method: Tensile strength: The tensile strength of the sample is tested according to the relevant test methods in GB / T 1040.2-2022 "Determination of tensile properties of plastics"; Thermal aging test: The tensile strength retention rate and elongation at break retention rate of the samples were tested according to the test method shown in GB / T 2951.12-2008 "General test methods for insulation and sheathing materials of cables and optical cables - Part 12: Thermal aging test method". The test conditions were aging in an air-circulating oven at 135℃ for 168h. The test results are shown in Table 1.

[0042] Table 1 Test Data Combining Examples 1-3 and Comparative Example 1 with Table 1, it can be seen that the experimental data of Examples 1-3 are all better than those of Comparative Example 1. This indicates that the addition of the modified nanoparticle filler prepared in this application forms a three-dimensional network structure in cross-linked polyethylene. The vinyl and amino groups grafted on its surface participate in the cross-linking reaction, which significantly improves the tensile strength and aging resistance of the material.

[0043] Based on Examples 1-3 and Comparative Example 2, and in conjunction with Table 1, it can be seen that the experimental data of Examples 1-3 are all better than those of Comparative Example 2, indicating that the modified montmorillonite optimizes the compatibility between montmorillonite and the matrix, and its addition significantly improves the mechanical properties and thermal stability of the cable material.

[0044] As can be seen from Examples 1 and 4-5 and Table 1, the modified nanoparticle filler prepared by the method of this application can improve the tensile strength and thermal aging performance of the cable when added to the cable raw material.

[0045] Combining Examples 1 and 6-8 with Table 1, it can be seen that the experimental data of Examples 6-8 are better than those of Example 1, indicating that the addition of zinc stearate further improves the processing fluidity and dispersibility, and at the same time reduces filler agglomeration through lubrication, thereby improving the mechanical properties and thermal stability of the material.

[0046] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A crosslinked polyethylene power cable, characterized in that, The raw materials include the following weight parts: 45-55 parts of ethylene-vinyl acetate copolymer, 2-4 parts of modified nano-particle filler, 30-40 parts of low-density polyethylene, 5-10 parts of polycaprolactone, 3-5 parts of modified montmorillonite, 8-12 parts of ethylene-methyl acrylate copolymer, 3-5 parts of phenyl silicone oil, 1.5-2.0 parts of crosslinking agent, 0.5-0.9 parts of antioxidant, and 1.5-2.5 parts of triazine derivative.

2. A crosslinked polyethylene power cable according to claim 1, characterized in that: The modified nano-particle filler is prepared by the following method: (1) Disperse the silicon dioxide nanoparticles in an ethanol solution, add vinyltrimethoxysilane, and react at 75-85°C for 2.5-3.5h. Centrifuge, wash, and dry to obtain the product for use; (2) Dissolve octavinylsilsesquioxane and azobisisobutyronitrile in toluene, add the product of step (1), and react at 80-90°C for 1.5-2.5h under nitrogen protection. Then, cool to 65-75°C, add γ-aminopropyltriethoxysilane, and react for 1-2h. After precipitation, centrifugation, washing, and drying, the modified nano-particle filler is obtained.

3. The crosslinked polyethylene power cable according to claim 2, characterized in that: the mass ratio of the silicon dioxide to the added vinyltrimethoxysilane is 1:0.17-0.25; the mass ratio of the silicon dioxide to the added octavinylsilsesquioxane is 1:0.17-0.21; the mass ratio of the silicon dioxide to the added γ-aminopropyltriethoxysilane is 1:0.09-0.

11.

4. A crosslinked polyethylene power cable according to claim 1, characterized in that: The modified montmorillonite is cetyltrimethylammonium bromide intercalated montmorillonite, and the preparation includes the following steps: Disperse sodium-based montmorillonite in deionized water, add cetyltrimethylammonium bromide, and stir and react at 75-85°C for 3-4h. After centrifugation, washing, drying, and sieving, the modified montmorillonite is obtained.

5. A crosslinked polyethylene power cable according to claim 1, characterized in that: The mass ratio of the sodium-based montmorillonite to the added cetyltrimethylammonium bromide is 1:0.32-0.

36.

6. A crosslinked polyethylene power cable according to claim 1, characterized in that: The triazine derivative is 2,4,6-triamino-1,3,5-triazine.

7. A crosslinked polyethylene power cable according to claim 1, characterized in that: 0.8-1.2 parts of zinc stearate are also added to the raw materials.

8. A process for the production of a crosslinked polyethylene power cable according to any one of claims 1 to 6, characterised in that, The following steps are included: Mix ethylene-vinyl acetate copolymer, low-density polyethylene, and polycaprolactone at 100-110°C for 3-5min. Add the modified montmorillonite, ethylene-methyl acrylate copolymer, phenyl silicone oil, modified nano-particle filler, and triazine derivative, and shear disperse at 110-130°C at a speed of 2500rpm for 15-20min. After mixing the crosslinking agent and antioxidant at 80-90°C, extrude, crosslink in a steam vulcanization pipeline at 170-180°C for 20-30min, cool to room temperature, and obtain the target product.

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