An insulated high-voltage power cable and a method for manufacturing the same

Abstract

The application relates to the technical field of cables, and discloses an insulated high-voltage power cable and a preparation method thereof. The insulated high-voltage power cable comprises a conductor, a crosslinked polyethylene insulation layer, a shielding layer, a semi-conductive water-blocking tape, an anticorrosion layer, a sheath layer and the like. Polyethylene, modified boron nitride, dicumyl peroxide and an antioxidant are mixed, extruded through a screw extruder, granulated, and the crosslinked polyethylene insulation layer is obtained. The compatibility of the modified boron nitride with the polyethylene is improved, the bonding force is improved, the modified boron nitride can be more uniformly dispersed in the polyethylene matrix, the mechanical properties and the thermal conductivity of the polyethylene insulation layer are improved, the breakdown field strength of the polyethylene insulation layer is increased, the high-voltage resistance of the polyethylene insulation layer is improved, and the polyethylene insulation layer can be better applied to high-insulation high-voltage power cable materials.

Description

Technical Field

[0001] This invention relates to the field of cable technology, specifically to an insulated high-voltage power cable and its manufacturing method. Background Technology

[0002] Power transmission cables mainly consist of conductors, insulation layers, and sheaths. The insulation layer primarily serves to electrically isolate the conductor from the external environment, preventing faults such as leakage and short circuits, thus ensuring safe and stable power transmission. The insulation layer is required to possess good high-voltage resistance, insulation strength, and mechanical protection. Cross-linked polyethylene (XLPE) is inexpensive, has good temperature resistance, and excellent insulation properties, making it widely used in cable insulation. However, XLPE has a relatively low breakdown field strength and poor high-voltage resistance, which hinders its practical application in high-voltage cables. Furthermore, cables generate a large amount of heat during power transmission that is difficult to dissipate, leading to heat accumulation and affecting cable safety. Therefore, improving the thermal conductivity of polyethylene materials used in cables is of great significance.

[0003] Modifying polyethylene with high-performance inorganic particles can improve its overall performance, enabling better practical applications in high-voltage cables and other applications. Boron nitride has high thermal conductivity, good insulation properties, and good voltage breakdown resistance, making it important in composite materials for thermal conductivity, insulation, and dielectric properties. Patent CN117209876B discloses a polyethylene cable material prepared using rare earth-based hydrotalcite, modified boron nitride nanosheets, aluminum-based organic framework, intercalating agent, thermoplastic elastomer, and polyethylene as raw materials, which exhibits good aging resistance and corrosion resistance. However, this patent does not improve the voltage resistance of polyethylene, making it difficult to meet the practical application requirements of polyethylene in high-voltage cables. Summary of the Invention

[0004] (i) This invention solves the problem of low thermal conductivity and dielectric properties of cross-linked polyethylene insulation layer.

[0005] (II) The technical solution of the present invention is: an insulated high-voltage power cable and its preparation method, wherein the insulated high-voltage power cable includes a conductor, a cross-linked polyethylene insulation layer, a shielding layer, a semi-conductive resistive water tape, a smooth aluminum layer, an anti-corrosion layer, a sheath layer, and a graphite coating.

[0006] Methods for preparing cross-linked polyethylene insulation layers include: S1. Add boron nitride and 4,7-dioleate-1,10-phenanthroline to isopropanol, stir to modify, filter, wash with ethanol, and dry to obtain modified boron nitride.

[0007] S2. Mix polyethylene, modified boron nitride, dicumyl peroxide, and antioxidant, extrude the mixture through a screw extruder, and granulate it to obtain a cross-linked polyethylene insulation layer.

[0008] Preferably, the conductor is a copper conductor or an aluminum conductor.

[0009] Preferably, the shielding layer is copper foil, copper strip, or copper braided mesh.

[0010] Preferably, the anti-corrosion layer is a polyethylene cold-applied anti-corrosion tape.

[0011] Preferably, the sheath layer is a polyethylene sheath layer or a polyvinyl chloride sheath layer.

[0012] Preferably, the modification in S1 is carried out at 20-40℃ for 3-6 hours.

[0013] Preferably, the mass ratio of boron nitride to 4,7-dioleate-1,10-phenanthroline in S1 is 100:(2-7). Preferably, the mass ratio of polyethylene, modified boron nitride, dicumyl peroxide, and antioxidant in S2 is 100:(5-20):(1-1.8):(0.15-0.3).

[0014] Preferably, the temperature of each section of the screw extruder in S2 is 160-190℃, and the screw speed is 40-80 r / min.

[0015] Preferably, the preparation method of 4,7-dioleoate-1,10-phenanthroline is as follows: 4,7-dihydroxy-1,10-phenanthroline and triethylamine are added to dichloromethane, and petroyl chloride is added dropwise in an ice bath to carry out an esterification reaction. Sodium bicarbonate solution is added, and after stirring, the mixture is allowed to stand and separate into layers. The organic layer is dried to remove water, and the product is washed with petroleum ether after vacuum distillation. Then, it is recrystallized in dichloromethane to obtain 4,7-dioleoate-1,10-phenanthroline. The reaction formula is: .

[0016] Preferably, the molar ratio of 4,7-dihydroxy-1,10-phenanthroline, triethylamine, and oleoyl chloride is 1:(2-2.2):(2-2.4).

[0017] Preferably, the esterification reaction is carried out at 15-30°C for 18-24 hours.

[0018] (III) Beneficial Technical Effects: The 4,7-dioleate-1,10-phenanthroline of this invention contains a bispyridine ring structure, which forms a π-π interaction with boron nitride, effectively achieving the dispersion modification of boron nitride. Then, it is mixed with polyethylene, dicumyl peroxide, etc., to obtain a cross-linked polyethylene insulation layer. The modified boron nitride surface introduces multiple long carbon chains, improving its compatibility with polyethylene and allowing for more uniform dispersion in the polyethylene matrix. This is beneficial for improving the mechanical properties and thermal conductivity of polyethylene. A higher thermal conductivity indicates better thermal performance, which facilitates heat dissipation during power transmission, reduces heat accumulation, and prevents excessively high cable operating temperatures, thereby improving cable safety and service life. Furthermore, the addition of boron nitride increases the breakdown field strength of the polyethylene insulation layer, improving its high-voltage resistance and making it more suitable for use in high-insulation, high-voltage power cable materials.

[0019] The unsaturated alkenyl groups in the long carbon chains on the surface of the modified boron nitride of this invention can chemically crosslink with polyethylene under the action of dicumyl peroxide, which enhances the bonding force between boron nitride and polyethylene, further improves the tensile strength and other properties of the polyethylene insulation layer, and can improve the mechanical properties and service life of the insulation layer and its cable. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of an insulated high-voltage power cable.

[0021] Figure 2 This is the infrared spectrum of 4,7-dioleoate-1,10-phenanthroline from Example 1. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] The following semiconducting water-resistant tape has a multi-layer composite structure, consisting of polyester non-woven fabric, a semiconducting adhesive layer, and a highly absorbent and water-blocking layer, and is sourced from Shenyang Tianrong Cable Materials Co., Ltd. The boron nitride used is hexagonal boron nitride with an average particle size of 5μm.

[0024] Example 1: An insulated high-voltage power cable, comprising a copper conductor, a cross-linked polyethylene insulation layer, a copper braided mesh, a semi-conductive resistive water tape, a smooth aluminum layer, a polyethylene cold-applied anti-corrosion tape, a polyvinyl chloride sheath layer, and a graphite coating. The preparation method of the cross-linked polyethylene insulation layer is as follows: (1) Add 3 mmol of 4,7-dihydroxy-1,10-phenanthroline and 6 mmol of triethylamine to 25 mL of dichloromethane. Add 6 mmol of oleyl chloride dropwise in an ice bath. Stir the reaction at 20 °C for 18 h. Add 10% sodium bicarbonate solution, stir, and allow to stand for separation. Dry the organic layer to remove water. Wash the product with petroleum ether after vacuum distillation. Then recrystallize in dichloromethane to obtain 4,7-dioleate-1,10-phenanthroline. Its infrared spectrum is shown in [reference needed]. Figure 2 , Figure 2 2929-2863cm -1 The absorption peaks are for methyl and methylene groups in long carbon chains, at 1724 cm⁻¹. -1 The absorption peak is the C=O group in the ester group, 1574-1475 cm⁻¹. -1 It is the absorption peak of the benzene ring skeleton.

[0025] (2) Add 100g of boron nitride and 2g of 4,7-dioleate-1,10-phenanthroline to 1.2L of isopropanol, stir at 30℃ for 3h to modify, filter, wash with ethanol, and dry to obtain modified boron nitride.

[0026] (3) Mix 2kg polyethylene, 100g modified boron nitride, 27g dicumyl peroxide and 3g antioxidant 1010, and extrude them through a screw extruder. The temperatures of each section are 160℃, 175℃, 190℃ and 190℃, and the screw speed is 40r / min. Granulate to obtain cross-linked polyethylene insulation layer.

[0027] Comparative Example 1: An insulated high-voltage power cable, comprising a copper conductor, a cross-linked polyethylene insulation layer, a copper braided mesh, a semi-conductive resistive water tape, a smooth aluminum layer, a polyethylene cold-applied anti-corrosion tape, a polyvinyl chloride sheath layer, and a graphite coating. The preparation method of the cross-linked polyethylene insulation layer is as follows: (1) Mix 2kg polyethylene, 100g boron nitride, 27g dicumyl peroxide and 3g antioxidant 1010, and extrude them through a screw extruder. The temperature of each section is 160℃, 175℃, 190℃ and 190℃, and the screw speed is 40r / min. Granulate to obtain cross-linked polyethylene insulation layer.

[0028] Comparative Example 2: An insulated high-voltage power cable, comprising a copper conductor, a cross-linked polyethylene insulation layer, a copper braided mesh, a semi-conductive resistive water tape, a smooth aluminum layer, a polyethylene cold-applied anti-corrosion tape, a polyvinyl chloride sheath layer, and a graphite coating. The preparation method of the cross-linked polyethylene insulation layer is as follows: (1) Add 100g boron nitride and 2g 4,7-dihydroxy-1,10-phenanthroline to 1.2L isopropanol, stir at 30℃ for 3h to modify, filter, wash with ethanol, and dry to obtain modified boron nitride.

[0029] (2) Mix 2kg polyethylene, 100g modified boron nitride, 27g dicumyl peroxide and 3g antioxidant 1010, and extrude them through a screw extruder. The temperatures of each section are 160℃, 175℃, 190℃ and 190℃, and the screw speed is 40r / min. Granulate to obtain cross-linked polyethylene insulation layer.

[0030] Comparative Example 3: An insulated high-voltage power cable, comprising a copper conductor, a cross-linked polyethylene insulation layer, a copper braided mesh, a semi-conductive resistive water tape, a smooth aluminum layer, a polyethylene cold-applied anti-corrosion tape, a polyvinyl chloride sheath layer, and a graphite coating. The preparation method of the cross-linked polyethylene insulation layer is as follows: (1) Add 3 mmol of 4,7-dihydroxy-1,10-phenanthroline and 6 mmol of triethylamine to 25 mL of dichloromethane. Add 6 mmol of stearoyl chloride dropwise in an ice bath. Stir the reaction at 20 °C for 18 h. Add a 10% sodium bicarbonate solution, stir, and allow to stand for separation. Dry the organic layer to remove water, distill under reduced pressure, wash the product with petroleum ether, and then recrystallize in dichloromethane to obtain 4,7-distearate-1,10-phenanthroline, with the structural formula: .

[0031] (2) Add 100g of boron nitride and 2g of 4,7-distearate-1,10-phenanthroline to 1.2L of isopropanol, stir at 30℃ for 3h to modify, filter, wash with ethanol, and dry to obtain modified boron nitride.

[0032] (3) Mix 2kg polyethylene, 100g modified boron nitride, 27g dicumyl peroxide and 3g antioxidant 1010, and extrude them through a screw extruder. The temperatures of each section are 160℃, 175℃, 190℃ and 190℃, and the screw speed is 40r / min. Granulate to obtain cross-linked polyethylene insulation layer.

[0033] Comparative Example 4: An insulated high-voltage power cable, comprising a copper conductor, a cross-linked polyethylene insulation layer, a copper braided mesh, a semi-conductive resistive water tape, a smooth aluminum layer, a polyethylene cold-applied anti-corrosion tape, a polyvinyl chloride sheath layer, and a graphite coating. The preparation method of the cross-linked polyethylene insulation layer is as follows: (1) Add 3 mmol of 4-hydroxypyridine and 3 mmol of triethylamine to 25 mL of dichloromethane. Add 3 mmol of oleyl chloride dropwise in an ice bath. Stir the reaction at 20 °C for 18 h. Add 10% sodium bicarbonate solution, stir, and allow to stand for separation. Dry the organic layer to remove water. Wash the product with petroleum ether after vacuum distillation. Then recrystallize in dichloromethane to obtain 4-oleate pyridine with the following structural formula: .

[0034] (2) Add 100g of boron nitride and 2g of 4-oleate pyridine to 1.2L of isopropanol, stir at 30℃ for 3h to modify, filter, wash with ethanol, and dry to obtain modified boron nitride.

[0035] (3) Mix 2kg polyethylene, 100g modified boron nitride, 27g dicumyl peroxide and 3g antioxidant 1010, and extrude them through a screw extruder. The temperatures of each section are 160℃, 175℃, 190℃ and 190℃, and the screw speed is 40r / min. Granulate to obtain cross-linked polyethylene insulation layer.

[0036] Example 2: An insulated high-voltage power cable, comprising a copper conductor, a cross-linked polyethylene insulation layer, copper tape, semi-conductive resistive water tape, a smooth aluminum layer, a polyethylene cold-applied anti-corrosion tape, a polyethylene sheath layer, and a graphite coating. The preparation method of the cross-linked polyethylene insulation layer is as follows: (1) Add 20 mmol of 4,7-dihydroxy-1,10-phenanthroline and 44 mmol of triethylamine to 180 mL of dichloromethane. Add 48 mmol of oleyl chloride dropwise in an ice bath. Stir the reaction at 15 °C for 24 h. Add 10% sodium bicarbonate solution. After stirring, allow the mixture to stand and separate into layers. Dry the organic layer to remove water. Wash the product with petroleum ether after vacuum distillation. Then recrystallize in dichloromethane to obtain 4,7-dioleate-1,10-phenanthroline.

[0037] (2) Add 250g of boron nitride and 13.8g of 4,7-dioleate-1,10-phenanthroline to 5L of isopropanol, stir at 40℃ for 3h to modify, filter, wash with ethanol, and dry to obtain modified boron nitride.

[0038] (3) Mix 3kg polyethylene, 250g modified boron nitride, 36g dicumyl peroxide and 6g antioxidant 1010, and extrude them through a screw extruder. The temperatures of each section are 160℃, 175℃, 190℃ and 190℃, and the screw speed is 40r / min. Granulate to obtain cross-linked polyethylene insulation layer.

[0039] Example 3: An insulated high-voltage power cable, comprising an aluminum conductor, a cross-linked polyethylene insulation layer, a copper braided mesh, a semi-conductive resistive water tape, a smooth aluminum layer, a polyethylene cold-applied anti-corrosion tape, a polyethylene sheath layer, and a graphite coating. The preparation method of the cross-linked polyethylene insulation layer is as follows: (1) Add 50 mmol of 4,7-dihydroxy-1,10-phenanthroline and 100 mmol of triethylamine to 450 mL of dichloromethane. Add 110 mmol of oleyl chloride dropwise in an ice bath. Stir the reaction at 30 °C for 18 h. Add 10% sodium bicarbonate solution. After stirring, allow the mixture to stand and separate into layers. Dry the organic layer to remove water. Wash the product with petroleum ether after vacuum distillation. Then recrystallize in dichloromethane to obtain 4,7-dioleate-1,10-phenanthroline.

[0040] (2) Add 400g of boron nitride and 28g of 4,7-dioleate-1,10-phenanthroline to 5L of isopropanol, stir at 20℃ for 6h to modify, filter, wash with ethanol, and dry to obtain modified boron nitride.

[0041] (3) Mix 2kg polyethylene, 400g modified boron nitride, 20g dicumyl peroxide and 3g antioxidant 1010, and extrude them through a screw extruder. The temperature of each section is 160℃, 175℃, 190℃ and 190℃, and the screw speed is 80r / min. Granulate to obtain cross-linked polyethylene insulation layer.

[0042] The cross-linked polyethylene insulation layer was injection molded into strips, and its tensile properties were tested according to standard GB / T 1040.1-2025.

[0043] Thermal conductivity shall be tested according to GB / T 42919.1-2023 standard.

[0044] The electrical performance and breakdown field strength E shall be tested according to GB / T 1408.1-2016 standard, where E=U / d, U is the breakdown voltage, and d is the thickness at the fault location when breakdown occurs.

[0045] Table 1 Performance Tests

[0046] The boron nitride in Comparative Example 1 exhibited poor dispersibility and incompatibility with polyethylene, resulting in low tensile strength, elongation at break, thermal conductivity, and breakdown field strength of the cross-linked polyethylene insulation layer, leading to poor mechanical properties, thermal conductivity, and high-voltage resistance. In Example 1, the 4,7-dioleate-1,10-phenanthroline contained a bispyridine ring structure, forming π-π interactions with boron nitride, achieving dispersion modification of boron nitride. Simultaneously, the presence of multiple long carbon chains improved compatibility with polyethylene, allowing for more uniform dispersion within the polyethylene matrix. This improved the mechanical properties and thermal conductivity of polyethylene, increased the breakdown field strength, and enhanced high-voltage resistance. Furthermore, the unsaturated alkenyl groups in the long carbon chains chemically cross-linked with polyethylene, strengthening the bond between boron nitride and polyethylene and further improving the tensile strength and other properties of polyethylene. Examples 2 and 3, by adjusting the ratio of polyethylene, modified boron nitride, and other raw materials, also prepared cross-linked polyethylene insulation layers with excellent mechanical, thermal conductivity, and high-voltage resistance properties.

[0047] Compared with Example 1, the 4,7-dihydroxy-1,10-phenanthroline in Comparative Example 2 does not contain long carbon chains and alkenyl groups. The modified boron nitride has lower compatibility and bonding strength with polyethylene, resulting in lower tensile properties, thermal conductivity and breakdown field strength of the cross-linked polyethylene insulation layer.

[0048] The 4,7-distearate-1,10-phenanthroline of Comparative Example 3 does not contain an alkenyl group and cannot chemically crosslink with polyethylene. The modified boron nitride has a lower bonding force with polyethylene, resulting in lower tensile strength and other properties of the crosslinked polyethylene insulation layer compared to Example 1.

[0049] The 4-oleate pyridine in Comparative Example 4 does not contain a bipyridine ring structure and has a weak π-π interaction with boron nitride, resulting in poor modification effect on boron nitride and causing the tensile strength and thermal conductivity of the cross-linked polyethylene insulation layer to be lower than those in Example 1.

[0050] The foregoing has shown and described the basic principles, main features, and characteristics of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for manufacturing an insulated high-voltage power cable, characterized in that, The insulated high-voltage power cable includes a conductor, a cross-linked polyethylene insulation layer, a shielding layer, a semi-conductive resistive water tape, a smooth aluminum layer, an anti-corrosion layer, a sheath layer, and a graphite coating. The method for preparing the cross-linked polyethylene insulation layer includes: S1. Add boron nitride and 4,7-dioleate-1,10-phenanthroline to isopropanol, stir to modify, filter, wash the product, and dry to obtain modified boron nitride. S2. Mix polyethylene, modified boron nitride, dicumyl peroxide, and antioxidant, extrude the mixture through a screw extruder, and granulate it to obtain a cross-linked polyethylene insulation layer.

2. The method for preparing an insulated high-voltage power cable according to claim 1, characterized in that, The conductor is a copper conductor or an aluminum conductor; the shielding layer is a copper foil, copper strip, or copper braided mesh.

3. The method for preparing an insulated high-voltage power cable according to claim 1, characterized in that, The anti-corrosion layer is a polyethylene cold-applied anti-corrosion tape; the sheath layer is a polyethylene sheath layer or a polyvinyl chloride sheath layer.

4. The method for preparing an insulated high-voltage power cable according to claim 1, characterized in that, The modification in S1 is carried out at 20-40℃ for 3-6 hours.

5. The method for preparing an insulated high-voltage power cable according to claim 1, characterized in that, The mass ratio of boron nitride to 4,7-dioleate-1,10-phenanthroline in S1 is 100:(2-7).

6. The method for preparing an insulated high-voltage power cable according to claim 1, characterized in that, The mass ratio of polyethylene, modified boron nitride, dicumyl peroxide, and antioxidant in S2 is 100:(5-20):(1-1.8):(0.15-0.3).

7. The method for preparing an insulated high-voltage power cable according to claim 1, characterized in that, The temperature of each section of the screw extruder in S2 is 160-190℃, and the screw speed is 40-80 r / min.

8. The method for preparing an insulated high-voltage power cable according to claim 1, characterized in that, The preparation method of the 4,7-dioleoate-1,10-phenanthroline is as follows: 4,7-dihydroxy-1,10-phenanthroline and triethylamine are added to dichloromethane, oleyl chloride is added dropwise in an ice bath, and the mixture is stirred at 15-30℃ for 18-24 h. Sodium bicarbonate solution is added, and after stirring, the mixture is allowed to stand and separate into layers. The organic layer is dried to remove water, and the product is washed by vacuum distillation and recrystallized to obtain 4,7-dioleoate-1,10-phenanthroline.

9. The method for preparing an insulated high-voltage power cable according to claim 8, characterized in that, The molar ratio of 4,7-dihydroxy-1,10-phenanthroline, triethylamine, and oleoyl chloride is 1:(2-2.2):(2-2.4).

10. An insulated high-voltage power cable obtained by the preparation method according to any one of claims 1-9.

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