10kV overhead insulated wire and preparation method thereof

Abstract

The invention relates to the technical field of cables, and provides a 10kV overhead insulated wire. The preparation method of the 10kV overhead insulated conductor comprises the following steps: dissolving aluminum isopropoxide in ethanol, adding water, and continuously stirring; then adding nano zinc oxide into the sol, and carrying out heat treatment to obtain AlOOH-coated ZnO; the preparation method comprises the following steps: ultrasonically dispersing AlOOH (at) ZnO in ethanol, then adding silane hydrolysate into the ethanol, and reacting at 70-80 DEG C for 2-3 hours to obtain silanized AlOOH (at) ZnO; carrying out primary mixing on high-density polyethylene, an ethylene-octylene copolymer and an antioxidant, adding silanized AlOOH (at) ZnO, organic montmorillonite, zinc stearate and polyethylene wax, and carrying out secondary mixing to obtain an insulating layer mixed material; and extruding and coating the outside of the conductor, and cooling and shaping to obtain the 10kV overhead insulated conductor. According to the 10kV overhead insulated wire, the insulativity and weather resistance of the wire are improved, and the mechanical performance of the wire is also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a 10kV overhead insulated conductor and a preparation method thereof. Background Art

[0002] In power transmission systems, 10kV overhead lines are a vital component of the distribution network, fulfilling the critical task of distributing electricity from substations to various users. Traditional overhead lines with bare conductors present numerous safety hazards during operation, such as electric shock accidents and short circuits caused by environmental influences. To ensure the safety and reliability of power transmission, 10kV insulated overhead conductors were developed. By coating the conductor with insulating material, they effectively avoid these issues and improve line operation stability and safety.

[0003] 10kV overhead insulated conductors play a vital role in power transmission. However, existing 10kV overhead insulated conductors and their preparation methods suffer from insufficient insulation performance, poor mechanical properties, poor weather resistance, and complex manufacturing processes. These issues not only impact the service life and safety of the conductors but also increase operating costs for power companies. Therefore, there is a need to develop a new 10kV overhead insulated conductor and its preparation method to address these shortcomings, improve conductor performance and quality, and meet the evolving needs of the power industry. To address these technical issues, the present invention proposes a new 10kV overhead insulated conductor. Summary of the Invention

[0004] The present invention provides a 10kV overhead insulated conductor, which improves the insulation and weather resistance of the conductor and also improves the mechanical properties of the conductor.

[0005] The technical solutions of the present invention are as follows: In a first aspect, the present invention provides a method for preparing a 10kV overhead insulated conductor, comprising the following steps: (1) Aluminum isopropoxide is dissolved in ethanol and stirred to obtain a transparent sol, and water is added and stirred continuously; nano zinc oxide is then added to the sol for impregnation and coating, and AlOOH@ZnO is obtained after heat treatment; (2) Silane coupling agent KH550 was added to a mixture of ethanol and water to obtain a silane hydrolyzate; AlOOH@ZnO was ultrasonically dispersed in ethanol, and then the silane hydrolyzate was added thereto, reacted at 70-80°C for 2-3h, centrifuged, washed, and dried to obtain silanized AlOOH@ZnO; (3) High-density polyethylene, ethylene-octene copolymer and antioxidant are mixed once, and silanized AlOOH@ZnO, organic montmorillonite, zinc stearate and polyethylene wax are added for secondary mixing to obtain an insulating layer mixture; (4) The mixed material is extruded and coated on the outside of the conductor using a twin-screw extruder, and dicumyl peroxide is injected online under control. After cooling and shaping, the 10 kV overhead insulated conductor is obtained.

[0006] As a further technical solution, the insulating layer compound includes the following raw materials in parts by weight: 100 parts of high-density polyethylene, 20-25 parts of AlOOH@ZnO, 8-10 parts of organic montmorillonite, 10-12 parts of ethylene-octene copolymer, 0.5-0.7 parts of antioxidant, 1.5-2 parts of dicumyl peroxide, 0.2-0.4 parts of zinc stearate, and 0.4-0.6 parts of polyethylene wax.

[0007] As a further technical solution, the weight ratio of aluminum isopropoxide, ethanol, water and nano zinc oxide in step (1) is 1: (10-15): (0.05-0.15): (0.3-0.5).

[0008] As a further technical solution, the stirring time for obtaining the transparent sol in step (1) is 30-40 minutes, and the stirring time after adding water is 60-70 minutes.

[0009] As a further technical solution, the heat treatment step in step (1) includes pre-drying at 75-85°C for 30-40 minutes, followed by annealing at 280-320°C for 60-70 minutes.

[0010] As a further technical solution, the method for preparing the hydrolysis solution in step (2) is as follows: adding the silane coupling agent KH550 to a mixture of ethanol and water, mixing and stirring, adding glacial acetic acid dropwise to adjust the pH to 4.5±0.1, and hydrolyzing at 35-45°C for 30-40 minutes; wherein the weight ratio of the silane coupling agent KH550, ethanol and water is 0.01-0.03:10-20:0.1-0.3.

[0011] As a further technical solution, the weight ratio of AlOOH@ZnO to silane coupling agent KH550 in step (2) is 1:0.1-0.3.

[0012] As a further technical solution, the first mixing in step (3) is mixing at 175-185°C for 5-8 minutes; the second mixing is mixing at 185-195°C and 60-70 rpm for 8-10 minutes.

[0013] As a further technical solution, in step (4), the L / D of the twin-screw extruder is ≤36, and the die head temperature is 190-200°C.

[0014] In a second aspect, the present invention provides a 10kV overhead insulated conductor, which is prepared using the aforementioned preparation method.

[0015] The working principle and beneficial effects of the present invention are: The present invention constructs a silanized AlOOH@ZnO composite filler through multi-step synergistic modification, achieving dual optimization of filler dispersibility and interfacial bonding strength. First, aluminum isopropylate is hydrolyzed to coat nano zinc oxide to form an AlOOH@ZnO core-shell structure, and the layered structure of AlOOH is used to inhibit ZnO agglomeration. At the same time, a stable crystalline phase structure is formed by heat treatment, providing uniform reaction sites for subsequent silanization. Secondly, the silane coupling agent KH550 is hydrolyzed under acidic conditions to generate silanol groups, which undergo condensation reaction with the hydroxyl groups on the AlOOH surface to form a chemically bonded silanized layer. This process not only enhances the compatibility of the filler with the polyethylene matrix, but also reduces interfacial stress concentration through the flexible transition of organic long chains, thereby effectively inhibiting interfacial debonding under mechanical load or wet heat aging conditions. Experiments show that the silanization treatment does not significantly change the electrical properties and flame retardancy, but significantly improves the tensile strength and wet heat aging resistance retention rate of the material through interface strengthening.

[0016] The present invention constructs a dual-filler system by introducing organic montmorillonite and silanized AlOOH@ZnO, utilizing the morphological differences between the two to form a complementary reinforcement mechanism. The organic montmorillonite is dispersed in the matrix in a lamellar structure, inhibiting crack propagation through physical barriers. At the same time, the organic groups modified on its surface interact with the silanized filler to produce van der Waals forces, promoting the continuity of the filler network. The silanized AlOOH@ZnO is filled in the gaps between the montmorillonite lamellar layers in the form of nanoparticles. This synergistic effect not only improves the mechanical strength of the material, but also reduces the water penetration path through the densification of the filler network, significantly improving the volume resistivity and resistance to wet-heat aging.

[0017] The present invention incorporates ethylene-octene copolymer into a high-density polyethylene (HDPE) matrix, modulating matrix toughness through its unique branched structure. When the material is subjected to external forces, the ethylene-octene copolymer absorbs energy through plastic deformation, inhibiting crack initiation and propagation, thereby compensating for the increased brittleness caused by inorganic fillers. Furthermore, the ethylene-octene copolymer exhibits superior resistance to wet-heat aging compared to HDPE. The tertiary carbon atoms in its molecular chain reduce hydrolysis reactivity through steric hindrance, slowing performance degradation caused by matrix degradation in wet-heat environments. Furthermore, the interfacial interaction between the ethylene-octene copolymer and the silanized filler further optimizes stress transfer efficiency. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0019] It should be noted that the high-density polyethylene in the present invention was purchased from PetroChina Jilin Petrochemical Company with the brand name DFDA-7042; the organic montmorillonite was purchased from Zhejiang Fenghong New Materials Co., Ltd. with the brand name DK1N; the ethylene-octene copolymer was purchased from Mitsui Chemicals with a melt index of 3.6 g / 10 min; and the polyethylene wax was purchased from Guangzhou Binlong Chemical Co., Ltd. with the model name D1100.

[0020] Example 1 This embodiment provides a 10kV overhead insulated conductor and a method for preparing the 10kV overhead insulated conductor, the steps comprising: (1) 10 g of aluminum isopropoxide was dissolved in 125 g of ethanol and stirred at 150 rpm for 35 min to obtain a transparent sol. 1 g of water was added and stirred for 65 min. 4 g of nano-zinc oxide was then added to the sol for impregnation and coating. The mixture was pre-dried at 80 °C for 35 min and then annealed at 300 °C for 65 min to obtain AlOOH@ZnO. (2) 0.02 g of silane coupling agent KH550 was added to a mixture of 15 g of ethanol and 0.2 g of water, and the mixture was stirred. Glacial acetic acid was added dropwise to adjust the pH to 4.5, and the mixture was hydrolyzed at 40 °C for 35 min to obtain a silane hydrolyzate. 1 g of AlOOH@ZnO was ultrasonically dispersed in 100 mL of ethanol, and the silane hydrolyzate was then added thereto. The mixture was reacted at 75 °C for 2.5 h, centrifuged at 8000 rpm for 5 min, washed with ethanol three times, and dried in vacuo at 60 °C for 12 h to obtain silanized AlOOH@ZnO. (3) 100 g of high-density polyethylene, 11 g of ethylene-octene copolymer, and 0.6 g of antioxidant 1010 were mixed at 180 °C for 6 min, and 22 g of silanized AlOOH@ZnO, 9 g of organic montmorillonite, 0.3 g of zinc stearate, and 0.5 g of polyethylene wax were added and mixed at 190 °C and 65 rpm for 9 min to obtain an insulating layer mixture; (4) The mixed material is extruded and coated on the outside of the conductor using a twin-screw extruder. The L / D of the twin-screw extruder is 36, the die temperature is 195°C, and 1.8 parts of diisopropylbenzene peroxide are controlled to be injected online. After cooling and shaping, a 10kV overhead insulated conductor is obtained.

[0021] Example 2 This embodiment provides a 10kV overhead insulated conductor and a method for preparing the 10kV overhead insulated conductor, the steps comprising: (1) 10 g of aluminum isopropoxide was dissolved in 100 g of ethanol and stirred at 150 rpm for 30 min to obtain a transparent sol. 0.5 g of water was added and stirred for 60 min. Subsequently, 3 g of nano-zinc oxide was added to the sol for impregnation and coating. The mixture was pre-dried at 75 °C for 30 min and then annealed at 280 °C for 60 min to obtain AlOOH@ZnO. (2) 0.01 g of silane coupling agent KH550 was added to a mixture of 10 g of ethanol and 0.1 g of water, and the mixture was stirred. Glacial acetic acid was added dropwise to adjust the pH to 4.5, and the mixture was hydrolyzed at 35 °C for 30 min to obtain a silane hydrolyzate. 1 g of AlOOH@ZnO was ultrasonically dispersed in 100 mL of ethanol, and the silane hydrolyzate was then added thereto. The mixture was reacted at 70 °C for 2 h, centrifuged at 8000 rpm for 5 min, washed with ethanol three times, and dried in vacuo at 60 °C for 12 h to obtain silanized AlOOH@ZnO. (3) 100 g of high-density polyethylene, 10 g of ethylene-octene copolymer and 0.5 g of antioxidant 1010 were mixed at 175 °C for 5 min, and 20 g of silanized AlOOH@ZnO, 8 g of organic montmorillonite, 0.2 g of zinc stearate and 0.4 g of polyethylene wax were added and mixed at 185 °C and 60 rpm for 8 min to obtain the insulation layer mixture; (4) The mixed material was extruded and coated on the outside of the conductor using a twin-screw extruder. The L / D of the twin-screw extruder was 36, the die temperature was 190°C, and 1.5g of diisopropylbenzene peroxide was injected online. After cooling and shaping, a 10kV overhead insulated conductor was obtained.

[0022] Example 3 This embodiment provides a 10kV overhead insulated conductor and a method for preparing the 10kV overhead insulated conductor, comprising the following steps: (1) 10 g of aluminum isopropoxide was dissolved in 150 g of ethanol and stirred at 150 rpm for 40 min to obtain a transparent sol. 1.5 g of water was added and stirred for 70 min. 5 g of nano-zinc oxide was then added to the sol for impregnation and coating. The mixture was pre-dried at 85 °C for 40 min and then annealed at 320 °C for 70 min to obtain AlOOH@ZnO. (2) 0.03 g of silane coupling agent KH550 was added to a mixture of 20 g of ethanol and 0.3 g of water, and the mixture was stirred. Glacial acetic acid was added dropwise to adjust the pH to 4.5, and the mixture was hydrolyzed at 45 °C for 40 min to obtain a silane hydrolyzate. 1 g of AlOOH@ZnO was ultrasonically dispersed in 100 mL of ethanol, and the silane hydrolyzate was then added thereto. The mixture was reacted at 80 °C for 3 h, centrifuged at 8000 rpm for 5 min, washed with ethanol three times, and dried in vacuo at 60 °C for 12 h to obtain silanized AlOOH@ZnO. (3) 100 g of high-density polyethylene, 12 g of ethylene-octene copolymer and 0.7 g of antioxidant 1010 were mixed at 185 °C for 8 min, and 25 g of silanized AlOOH@ZnO, 10 g of organic montmorillonite, 0.4 g of zinc stearate and 0.6 g of polyethylene wax were added and mixed at 195 °C and 70 rpm for 10 min to obtain an insulating layer mixture; (4) The mixed material is extruded and coated on the outside of the conductor using a twin-screw extruder. The L / D of the twin-screw extruder is 36, the die temperature is 200°C, and 2g of diisopropylbenzene peroxide is injected online. After cooling and shaping, a 10kV overhead insulated conductor is obtained.

[0023] Comparative Example 1 Adjustments were made based on Example 1, except that no AlOOH@ZnO and organic montmorillonite were added.

[0024] Comparative Example 2 Adjustments were made based on Example 1, except that ordinary ZnO replaced AlOOH@ZnO, and the aluminum isopropoxide coating step was omitted.

[0025] Comparative Example 3 Adjustments were made based on Example 1, except that step (2) was skipped and non-silanized AlOOH@ZnO was directly used.

[0026] Comparative Example 4 Adjustments were made based on Example 1, except that the amount of silanized AlOOH@ZnO was reduced to 5 g.

[0027] Comparative Example 5 Adjustments were made based on Example 1, except that the amount of silanized AlOOH@ZnO was increased to 40 g.

[0028] Comparative Example 6 Adjustments were made based on Example 1, except that the ethylene-octene copolymer was omitted.

[0029] Comparative Example 7 Adjustments were made based on Example 1, except that the organic montmorillonite was omitted.

[0030] Comparative Example 8 Adjustments were made based on Example 1, except that the silanized AlOOH@ZnO was omitted.

[0031] Test Example 1: The following tests were performed on the 10 kV overhead insulated conductors prepared in Examples 1-3 and Comparative Examples 1-8: Tensile strength: tested in accordance with GB / T1040.2-2006 standard; Volume resistivity: Measure the resistivity at 20°C according to GB / 15662 standard; Limiting Oxygen Index (LOI): Tested in accordance with GB / T 2406.2-2009 standard; Moisture-heat aging resistance: Hang the outer layer sample (100mm×100mm×2mm) wrapped around the conductor in an aging chamber at 85°C and 85% RH for 168 hours. Test the tensile strength and calculate the tensile strength retention rate. The test results are shown in Table 1 below: Table 1

[0032] Combined with the above data, Examples 1-3 demonstrate optimized 10kV overhead insulated conductor performance. The combination of silanized AlOOH@ZnO and organic montmorillonite, combined with ethylene-octene copolymer, significantly improves tensile strength, volume resistivity, limiting oxygen index, and resistance to wet heat aging. Example 1 performs best, with a tensile strength of 22.1 MPa and a volume resistivity of 1.8×10 15 Ω·cm, LOI 33.2%, and retention 92%, indicating good filler dispersion and strong interfacial bonding. The performance variations of Comparative Examples 1-8 confirm the role of key components: AlOOH@ZnO coating and silanization are key to improving insulation and aging resistance; ethylene-octene copolymer improves toughness; and the filler dosage must be moderate; excessive or insufficient filler leads to performance degradation.

[0033] Comparative Example 1 does not add AlOOH@ZnO and organic montmorillonite at all, and all properties decrease significantly, indicating that AlOOH@ZnO and organic montmorillonite are the key to improving mechanical strength, insulation, flame retardancy and aging resistance. After the loss, the matrix resin cannot effectively resist aging and stress. Comparative Example 2 Ordinary ZnO replaces AlOOH@ZnO, omitting the isopropyl aluminum coating, and the performance is slightly lower than that of Example 1, indicating that the AlOOH coating layer can improve ZnO dispersion and interface bonding, improve insulation and aging resistance; ordinary ZnO is easy to agglomerate, resulting in a decrease in electrical and mechanical properties. Comparative Example 3 directly uses unsilanized AlOOH@ZnO, skipping step (2), and the tensile strength and retention rate are significantly reduced. The volume resistivity and LOI are similar to those of the examples, indicating that the silanization treatment does not directly affect the electrical properties and flame retardancy, but can enhance the filler-matrix interface bonding and prevent interface degradation caused by wet heat aging. In Comparative Example 4, when the silanized AlOOH@ZnO dosage was reduced to 5g, performance declined across the board. This indicates that insufficient filler dosage failed to effectively reinforce the matrix, leading to insufficient insulation, flame retardancy, and mechanical strength. The appropriate amount of filler is crucial for overall performance. In Comparative Example 5, when the silanized AlOOH@ZnO dosage was increased to 40g, tensile strength and volume resistivity decreased, while LOI increased slightly but retention was acceptable. This indicates that excessive filler leads to agglomeration, reducing mechanical strength and insulation. Although flame retardancy improved, it is susceptible to embrittlement in practical applications, making it unsuitable for high-voltage insulated conductors. In Comparative Example 6, when the ethylene-octene copolymer was omitted, tensile strength increased slightly but retention decreased significantly. Volume resistivity and LOI changed little, indicating that the absence of the ethylene-octene copolymer rendered the material brittle. Initial strength was high, but resistance to wet-heat aging was poor. The ethylene-octene copolymer is essential for improving toughness and durability. In Comparative Example 7, when the organic montmorillonite was omitted, performance declined moderately, indicating that the organic montmorillonite contributes to mechanical reinforcement and flame retardancy. Its omission incompletely fills the filler system, weakening the insulation layer's aging resistance. Comparative Example 8, in which the silanized AlOOH@ZnO is omitted, exhibits a significant overall degradation in performance, demonstrating that the silanized AlOOH@ZnO is a core functional filler, providing insulation, flame retardancy, and reinforcement. Its omission is similar to Comparative Example 1, but the residual montmorillonite partially mitigates the decline. The performance degradation in Comparative Examples 1 and 7 further demonstrates the necessity of a dual-filler system, demonstrating that a single filler cannot simultaneously achieve a balance between mechanical reinforcement and insulation weatherability. The significant decrease in tensile strength retention in Comparative Example 6 confirms the critical role of ethylene-octene copolymer in long-term durability.

[0034] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a 10kV overhead insulated conductor, characterized in that the steps include: (1) Dissolve aluminum isopropoxide in ethanol, stir to obtain a transparent sol, add water and continue stirring; Then, nano zinc oxide was added into the sol for impregnation coating, and AlOOH@ZnO was obtained after heat treatment; (2) Silane coupling agent KH550 was added to a mixture of ethanol and water to obtain a silane hydrolyzate; AlOOH@ZnO was ultrasonically dispersed in ethanol, and then the silane hydrolyzate was added thereto, reacted at 70-80°C for 2-3h, centrifuged, washed, and dried to obtain silanized AlOOH@ZnO; (3) High-density polyethylene, ethylene-octene copolymer and antioxidant are mixed once, and silanized AlOOH@ZnO, organic montmorillonite, zinc stearate and polyethylene wax are added for secondary mixing to obtain an insulating layer mixture; (4) The mixed material is extruded and coated on the outside of the conductor using a twin-screw extruder, and dicumyl peroxide is injected online under control. After cooling and shaping, the 10 kV overhead insulated conductor is obtained.

2. The method for preparing a 10kV overhead insulated conductor according to claim 1, characterized in that: The insulating layer compound comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene, 20-25 parts of AlOOH@ZnO, 8-10 parts of organic montmorillonite, 10-12 parts of ethylene-octene copolymer, 0.5-0.7 parts of antioxidant, 1.5-2 parts of dicumyl peroxide, 0.2-0.4 parts of zinc stearate, and 0.4-0.6 parts of polyethylene wax.

3. The method for preparing a 10kV overhead insulated conductor according to claim 1, characterized in that: The weight ratio of the aluminum isopropoxide, the ethanol, the water and the nano zinc oxide in step (1) is 1: (10-15): (0.05-0.15): (0.3-0.5).

4. The method for preparing a 10kV overhead insulated conductor according to claim 1, characterized in that: The stirring time for obtaining the transparent sol in step (1) is 30-40 min, and the stirring time after adding water is 60-70 min.

5. The method for preparing a 10kV overhead insulated conductor according to claim 1, characterized in that: The heat treatment step in step (1) includes: pre-drying at 75-85°C for 30-40 minutes, followed by annealing at 280-320°C for 60-70 minutes.

6. The method for preparing a 10kV overhead insulated conductor according to claim 1, characterized in that: The preparation method of the silane hydrolyzate in step (2) is as follows: adding the silane coupling agent KH550 to a mixture of ethanol and water, mixing and stirring, adding glacial acetic acid to adjust the pH to 4.5±0.1, and hydrolyzing at 35-45°C for 30-40 minutes; wherein the weight ratio of the silane coupling agent KH550, ethanol and water is 0.01-0.03:10-20:0.1-0.

3.

7. The method for preparing a 10kV overhead insulated conductor according to claim 1, characterized in that: The weight ratio of the AlOOH@ZnO and the silane coupling agent KH550 in step (2) is 1:0.1-0.

3.

8. The method for preparing a 10kV overhead insulated conductor according to claim 1, characterized in that: The first mixing in step (3) is mixing at 175-185°C for 5-8 minutes; the second mixing is mixing at 185-195°C and 60-70 rpm for 8-10 minutes.

9. The method for preparing a 10kV overhead insulated conductor according to claim 1, characterized in that: The twin-screw extruder in step (4) has an L / D of ≤36 and a die head temperature of 190-200°C.

10. A 10kV overhead insulated conductor, characterized in that: The 10kV overhead insulated conductor is prepared by the preparation method of any one of claims 1 to 9.

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