Low dielectric loss low voltage power cable

Abstract

The application discloses a low dielectric loss low-voltage power cable and belongs to the field of low-voltage cables. The application mainly aims at the problem that the dielectric stability, electric tracking resistance and mechanical property retention rate of the low-voltage power cable need to be further improved during long-term service, and specifically comprises a plurality of cable cores and an outer sheath layer. The cable core comprises a conductor and a low dielectric loss insulating layer wrapped outside the conductor. The low dielectric loss insulating layer comprises a polyolefin resin matrix, an interface reaction master batch and an additive aid. After a hindered phenol aramid calcium coordination functional shell layer is constructed on the surface of boron nitride, a polyolefin bridging coating layer with a benzophenone group modification is introduced. The interface polarization caused by the direct exposure of the polar group is reduced, the free carrier migration and local electric field distortion are inhibited, and the thermal oxygen aging stability is improved through the blocking effect of the immobilized hindered phenol and boron nitride sheet layer.

Description

Technical Field

[0001] This invention relates to the field of low-voltage cables, and more specifically to a low-voltage power cable with low dielectric loss. Background Technology

[0002] Low-voltage power cables are widely used in building power distribution, industrial equipment power supply, rail transit, data centers and new energy supporting facilities. The insulation performance is directly related to the safety, stability and service life of the cable operation. The insulation materials of conventional low-voltage power cables are mostly polyvinyl chloride, polyethylene, cross-linked polyethylene, polypropylene or their blended modified materials. Among them, polyolefin materials have a low dielectric constant, good processing performance and electrical insulation performance, and have high application value in the field of cable insulation.

[0003] However, ordinary polyolefin materials are prone to molecular chain breakage, oxidative degradation, and interface defect propagation under the long-term combined effects of heat, oxygen, and electric field, which in turn generate polar oxidation products such as carbonyl and hydroxyl groups. This leads to increased dielectric loss and decreased volume resistivity of the insulation layer, as well as reduced tracking resistance and mechanical retention of the cable. Hindered phenolic antioxidants, phosphite auxiliary antioxidants, or other stabilizers are often added to the resin system to improve the heat oxidation resistance of polyolefin insulation materials. However, small molecule antioxidants are prone to migration, volatilization, or precipitation during cable extrusion and long-term service, resulting in a decrease in antioxidant effect. At the same time, the precipitated polar additives may also affect the dielectric stability of the insulation layer.

[0004] In addition, to improve the thermal conductivity, dimensional stability, or tracking resistance of insulation materials, some technical solutions involve adding inorganic fillers to polyolefins. However, inorganic fillers have poor compatibility with non-polar polyolefin matrices. When the polar groups on the filler surface are directly exposed, interfacial polarization and charge accumulation are easily formed, which may lead to increased dielectric loss, local electric field distortion, and interfacial debonding, micropores, and microcracks after aging. As a result, the dielectric stability, tracking resistance, and mechanical property retention of cables during long-term service need to be further improved. Summary of the Invention

[0005] The purpose of this invention is to provide a low-voltage power cable with low dielectric loss, which solves the technical problem that the dielectric stability, tracking resistance and mechanical property retention rate of low-voltage power cables in the prior art need to be further improved during long-term service.

[0006] The objective of this invention can be achieved through the following technical solution: a low-voltage power cable with low dielectric loss, comprising a plurality of cable cores and an outer sheath, wherein the cable cores comprise a conductor and a low-dielectric-loss insulation layer covering the conductor.

[0007] The low dielectric loss insulating layer comprises the following components by weight: 100 parts of polyolefin resin matrix, 12-16 parts of interface reaction masterbatch, and 1 part of additives.

[0008] The polyolefin resin matrix comprises the following components by weight: 70-80 parts polypropylene, 20-30 parts propylene-ethylene random copolymer, 18-23 parts ethylene-octene copolymer, and 5-8 parts maleic anhydride-grafted polypropylene.

[0009] The interfacial reaction masterbatch is composed of hindered phenolamine calcium coordination modified boron nitride and reactive bridging polyolefin in a weight ratio of 1:7-8.

[0010] Furthermore, the conductor is formed by stranding several copper wires with a diameter of 2±0.2 mm and a cross-sectional area of ​​100±5 mm². 2 .

[0011] Furthermore, the hindered phenolamine calcium coordination modified boron nitride is obtained by the following steps:

[0012] A1. Under an inert gas atmosphere, 5-aminoisophthalic acid, N,N-dimethylformamide, and triethylamine were mixed and stirred until dissolved. The reaction system was cooled to 0-5℃, and 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride solution was added dropwise to the reaction system. After the addition was complete, the reaction system was heated to 55-65℃ and kept at this temperature for 4-6 hours. After post-treatment, hindered phenolic aromatic amide carboxylic acid ligands were obtained.

[0013] A2. Under an inert gas atmosphere, amino-modified boron nitride, hindered phenolic aromatic amide carboxylic acid ligand, and N,N-dimethylformamide were mixed and stirred. At room temperature, N,N'-dicyclohexylcarbodiimide and N-hydroxysuccinimide were added to the reaction system. The reaction was maintained at this temperature for 6-8 hours. After filtration, the filter cake was mixed with calcium acetate solution. The reaction system was heated to 60-65℃ and stirred at this temperature for 4-5 hours. After post-treatment, hindered phenolic amine calcium coordination modified boron nitride was obtained.

[0014] Further, in step A1, the ratio of 5-aminoisophthalic acid, N,N-dimethylformamide, and triethylamine is 1g:8-10mL:0.5-0.6g. The 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride solution is composed of 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride and N,N-dimethylformamide in a weight ratio of 1:3. The molar ratio of 5-aminoisophthalic acid to 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride is 1:1. The post-treatment includes: after the reaction is complete, cooling the reaction system to room temperature, pouring the reaction solution into deionized water, stirring and dispersing for 20-30 minutes, filtering, washing the filter cake three times with deionized water, drying it, and then transferring it to a drying oven at 60-70℃ to dry it to constant weight to obtain the hindered phenolic aromatic amide carboxylic acid ligand.

[0015] Further, in step A2, the ratio of the amount of the amino-modified boron nitride, the hindered phenolic aromatic amide carboxylic acid ligand, N,N-dimethylformamide, N,N'-dicyclohexylcarbodiimide, N-hydroxysuccinimide, and calcium acetate solution is 50g:8-10g:400-500mL:2.8-3.2g:0.9-1.3g:600mL. The calcium acetate solution is composed of calcium acetate, tetrahydrofuran, and deionized water in a ratio of 4-5g:8mL:20mL. The post-treatment includes: after the reaction is complete, cooling the reaction system to room temperature, filtering, washing the filter cake three times with purified water and drying it under vacuum, transferring the filter cake to a drying oven at 70-80℃, and drying it to constant weight to obtain hindered phenolic amine calcium coordination modified boron nitride.

[0016] Furthermore, the preparation method of reactive bridging polyolefin is as follows: polypropylene, 4-allyloxy-2-hydroxybenzophenone, glycidyl methacrylate and initiator are mixed evenly and then added to a twin-screw extruder. After melting and mixing for 60-80 seconds, the mixture is extruded, cooled and pelletized, extracted with acetone under reflux for 12 hours, and then vacuum dried at 65-75℃ for 8-9 hours to obtain reactive bridging polyolefin.

[0017] Furthermore, the weight ratio of polypropylene, 4-allyloxy-2-hydroxybenzophenone, glycidyl methacrylate and initiator is 100:1.2-1.5:0.8-1:0.05, the initiator is dicumyl peroxide, the temperature of the five temperature zones of the twin-screw extruder is 165℃, 175℃, 185℃, 190℃ and 190℃ respectively, the die head temperature is 190℃, and the solid-liquid ratio of extrudate to acetone is 1:7-8.

[0018] Furthermore, the preparation method of aminated boron nitride is as follows: nano boron nitride, γ-aminopropyltriethoxysilane and anhydrous ethanol are mixed and stirred, sodium hydroxide solution is added to the reaction system, the reaction system is heated to 60-65℃, and the reaction is maintained for 4-6 hours. After post-treatment, aminated boron nitride is obtained.

[0019] Furthermore, the ratio of the amount of nano-boron nitride, γ-aminopropyltriethoxysilane, anhydrous ethanol, and sodium hydroxide solution is 10g:1.0-1.4g:100mL:6-8mL, and the concentration of the sodium hydroxide solution is 4-5mol / L. The post-treatment includes: after the reaction is complete, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral, dried, and the filter cake is transferred to a drying oven at 60-70℃ and dried to constant weight to obtain amino-bond nitride.

[0020] Furthermore, the method for preparing the cable core is as follows:

[0021] S1. Place the hindered phenolamine calcium coordination modified boron nitride and reactive bridging polyolefin in a mixer, set the mixing temperature to 170-180℃, mix for 6-8 minutes, cool down and pelletize to obtain the interface reaction masterbatch.

[0022] S2. After uniformly mixing the polyolefin resin matrix, interfacial reaction masterbatch, and additives, place them in a twin-screw extruder and melt mix for 40-60 seconds. After extrusion, cool and pelletize to obtain low dielectric loss insulating granules.

[0023] S3. Place the low dielectric loss insulating granules in a single screw extruder and melt-extrude them to coat the outside of the conductor, forming a low dielectric loss insulating layer with a thickness of 5±0.1mm, thus obtaining the cable core.

[0024] Furthermore, in step S2, the temperatures of the five temperature zones of the twin-screw extruder are 165℃, 175℃, 185℃, 190℃, and 190℃ respectively, and the die head temperature is 190℃; in step S3, the barrel temperature of the single-screw extruder is 185-195℃, the die head temperature is 195℃, and the conductor temperature is 80-90℃. After extrusion and coating, the conductor is cooled in a 90℃ hot water bath for 30-50 seconds, then cooled and shaped in a 20-25℃ cold water bath, and finally annealed at 115℃ for 15-20 minutes to obtain the cable core.

[0025] The present invention has the following beneficial effects:

[0026] 1. This invention involves placing filler ropes between multiple low-dielectric-loss insulated cable cores, resulting in a more rounded cable structure, more uniform stress distribution, and reduced insulation layer deformation and electric field distortion caused by local compression. The polyester wrapping tape, forming a wrapping layer, constrains the position of the cable cores and filler ropes, maintaining the stability of the cable core structure. A metal foil shielding layer is placed outside the wrapping layer, reducing the impact of external electromagnetic interference on cable operation and suppressing electromagnetic leakage within the cable itself. The outer sheath tightly covers the outside of the shielding layer. Different sheath materials are selected to improve the overall mechanical strength, wear resistance, and environmental protection capabilities of the cable. This provides a foundation for high insulation, low loss, and aging resistance with the low-dielectric-loss insulation layer. The external filler, wrapping, shielding, and sheathing structures further ensure the structural stability, electromagnetic stability, and service reliability of the cable after assembly, allowing the low-dielectric-loss insulated cable cores to play an effective role in the overall structure of low-voltage power cables.

[0027] 2. This invention also modifies the hindered phenolic structure by amidation reaction between acyl chloride and amino groups, thereby enabling the hindered phenolic aromatic amide carboxylic acid ligand to simultaneously possess free radical scavenging groups, reactive carboxyl groups, and metal coordination sites; aminated the surface of nano-boron nitride through silane hydrolysis and condensation, transforming the relatively inert inorganic interface of boron nitride into a reactive amino interface; and then, through the DCC / NHS activation amidation reaction mechanism, covalently fixes the hindered phenolic aromatic amide carboxylic acid ligand onto the aminated boron nitride surface, and further... The coordination reaction mechanism between carboxyl groups and calcium ions allows for calcium coordination modification of ligand-coated boron nitride, forming a functional shell on the boron nitride surface that integrates immobilized hindered phenolic, aromatic amide, and calcium carboxylate structures. This prevents the migration, volatilization, or precipitation of hindered phenolic structures during processing and use. The calcium coordination structure can form charge-trapping sites at the filler interface and regulate the crystallization behavior of polypropylene. The boron nitride sheets can extend the charge migration path and the thermo-oxidative diffusion path, thus providing a basis for improving the volume resistivity, thermal oxidation resistance, and electrical stability of the insulating layer.

[0028] 3. This invention also utilizes a peroxide-initiated free radical grafting reaction to synergistically graft benzophenone groups and epoxy groups onto polypropylene, enabling the reactive bridging polyolefin to simultaneously possess polypropylene segments compatible with the polyolefin resin matrix, a benzophenone structure that regulates high-energy electrons and interfacial charges, and epoxy groups capable of reacting with the surface-active groups of modified boron nitride. Furthermore, through the ring-opening reaction mechanism between epoxy groups and carboxyl, amino, or hydroxyl groups, the hindered phenolic amine calcium coordination-modified boron nitride undergoes polyolefin bridging and coating modification, chemically anchoring the polypropylene segments to the modified boron nitride surface, forming boron nitride sheets and hindered phenolic amine calcium. The composite interface structure of the coordination shell and the polyolefin bridging layer allows the polar groups such as amides and carboxylates on the boron nitride surface to be partially consumed by the reaction or shielded by the polyolefin segments, reducing interfacial polarization caused by direct exposure of the polar interface. At the same time, the benzophenone structure and calcium coordination structure are concentrated in the filler interface region where charge accumulation is prone to occur, forming mutually complementary charge traps and voltage stabilization regions, reducing the mobility of free carriers and reducing local electric field distortion. This allows the insulating layer to maintain a high volume resistivity and a low power frequency and high frequency dielectric loss factor while introducing antioxidant, nucleation and voltage stabilization functional structures. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] In this application, the propylene-ethylene random copolymer is selected from commercially available materials from Yuyao Changrun Plastic Raw Materials Co., Ltd., with the grade E1016PL.

[0031] In this application, the polypropylene is injection molding grade PP, selected from commercially available materials from Yanshan Petrochemical, with the grade name K1020;

[0032] In this application, the ethylene-octene copolymer is injection molding grade, selected from commercially available materials from Dow Chemical, with the grade 8401;

[0033] In this application, the maleic anhydride-grafted polypropylene is a commercially available injection molding grade material with a maleic anhydride grafting rate of 1.5-1.7% and a melt flow index of 500-580 g / 10 min.

[0034] In this application, the nano boron nitride is commercially available flake boron nitride with a particle size of 1-10 μm and a boron content of 43.6%.

[0035] Example 1

[0036] This embodiment provides a low-voltage power cable with low dielectric loss, comprising, from the inside out, the following:

[0037] The conductive layer includes several parallel cable cores, wherein the cable cores are low dielectric loss insulated cable cores;

[0038] Filler rope, used to fill the gaps between several cable cores;

[0039] The wrapping layer is made by wrapping polyester wrapping tape around the outside of several cable cores and filler rope;

[0040] The shielding layer, consisting of metal foil wrapped around the outside of the wrapping layer, is used to improve the electromagnetic shielding performance of the cable, reduce the impact of external electromagnetic interference on the transmission stability of the cable, and suppress electromagnetic leakage generated during cable operation.

[0041] The outer sheath is formed by extrusion molding and is wrapped around the outside of the shielding layer. The outer sheath is tightly bonded to the shielding layer, and the structure is uniform and continuous, which improves the overall mechanical strength and environmental resistance of the cable.

[0042] Example 2

[0043] This embodiment provides a method for preparing a low dielectric loss insulated cable core, including the following steps:

[0044] Step 1: Preparation of hindered phenolic aromatic amide carboxylic acid ligands

[0045] Weigh out 59.4 g of 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride and 178.2 g of N,N-dimethylformamide, mix them evenly to obtain a 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride solution;

[0046] Weigh out 36.3 g of 5-aminoisophthalic acid, 290 mL of N,N-dimethylformamide, and 18.2 g of triethylamine and add them to an argon-protected reaction flask. Stir until the system dissolves. Cool the reaction flask to 0 °C and add the prepared 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride solution dropwise to the reaction flask. After the addition is complete, heat the reaction flask to 55 °C and keep it at this temperature for 4 h. Cool the reaction flask to room temperature and pour the reaction solution into a reaction flask containing 1 L of deionized water. Stir and disperse for 20 min, filter, wash the filter cake three times with deionized water, dry it under vacuum, and then transfer it to a drying oven at 60 °C to dry to constant weight to obtain the hindered phenolic aromatic amide carboxylic acid ligand.

[0047] In the reaction, the acyl chloride group in 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride undergoes a nucleophilic substitution reaction with the amino group in the 5-aminoisophthalic acid molecule to form an amide bond, while releasing hydrogen chloride. Triethylamine acts as an acid-binding agent in the system, absorbing the hydrogen chloride generated in the reaction and preventing hydrogen chloride from inhibiting the amino reaction or causing side reactions. The hindered phenolic structure is introduced into the aromatic amide molecule containing the carboxylic acid group, so that the resulting ligand has the ability to capture hindered phenolic free radicals, the stability of the amide structure, and the ability to react with carboxyl groups and coordinate with metals. This structure can be subsequently fixed on the surface of boron nitride, avoiding the migration, volatilization or precipitation of traditional small molecule hindered phenolic antioxidants during cable processing and service, reducing the increase of dielectric loss factor tanδ after thermo-oxidative aging, and improving the elongation at break retention rate.

[0048] 1H NMR data of hindered phenolic aromatic amide carboxylic acid ligands: 1 ¹H NMR (400 MHz, DMSO-d6) δ: 12.95 (brs, 2H, -COOH), 10.34 (s, 1H, -CONH-), 8.91 (s, 1H, Ar-OH), 8.48 (t, J=1.6 Hz, 1H, isophthalic acid ring Ar-H), 8.17 (d, J=1.6 Hz, 2H, isophthalic acid ring Ar-H), 6.96 (s, 2H, hindered phenolic ring Ar-H), 2.77 (t, J=7.6 Hz, 2H, Ar-CH2-), 2.60 (t, J=7.6 Hz, 2H, -CH2-CONH-), 1.34 (s, 18H, -C(CH3)3).

[0049] In the 1H NMR spectroscopy data, the broad peak near δ12.95 corresponds to the carboxyl proton in the isophthalic acid structure, indicating that the carboxylic acid functional group in the target ligand is preserved; the singlet near δ10.34 is attributed to the amide proton, indicating that the acyl chloride group undergoes an amidation reaction with the amino group in 5-aminoisophthalic acid, forming a –CONH– linkage structure; the aromatic hydrogen signals near δ8.48 and δ8.17 correspond to the three protons on the aromatic ring of isophthalic acid, with the integral ratio of 1H and 2H consistent with the 1,3,5-trisubstituted benzene ring structure; the singlet near δ6.96 corresponds to the symmetrical fractionation in the 3,5-di-tert-butyl-4-hydroxyphenyl structure. The presence of two aromatic hydrogens indicates that the hindered phenolic ring structure has been incorporated into the hindered phenolic aromatic amide carboxylic acid ligand molecule. The triplet near δ2.77 is attributed to the benzylic methylene Ar-CH2- linked to the hindered phenolic ring, and the triplet near δ2.60 is attributed to the -CH2-CONH- near the amide carbonyl group. The integrals of both methylene peaks are 2H, and they exhibit similar coupling constants, consistent with the structural characteristics of the -Ar-CH2-CH2-CONH- fragment. The strong singlet near δ1.34 has an integral of 18H, corresponding to the methyl protons in the two tert-butyl groups, verifying that the target product retains the 3,5-di-tert-butyl hindered phenolic structure.

[0050] Step 2: Preparation of amino-modified boron nitride

[0051] Weigh 100g of nano boron nitride, 10g of γ-aminopropyltriethoxysilane, and 1000mL of anhydrous ethanol and add them to a reaction flask. Stir the mixture and add 60mL of 4mol / L sodium hydroxide solution to the reaction flask. Heat the reaction flask to 60℃ and keep it at that temperature for 4h. Cool the reaction flask to room temperature, filter the mixture, wash the filter cake with purified water until neutral, and then dry it under vacuum. Transfer the filter cake to a drying oven at 60℃ and dry it to constant weight to obtain amino boron nitride.

[0052] In the reaction, γ-aminopropyltriethoxysilane undergoes hydrolysis under ethanol and alkaline conditions, and the ethoxy group is converted into a silanol group, which condenses with the surface active group of boron nitride to form a Si-OB linkage structure. An aminopropyl group is introduced on the surface of boron nitride. The amination treatment provides a basis for subsequent covalent grafting and interface stabilization.

[0053] Step 3: Preparation of hindered phenolamine calcium coordination modified boron nitride

[0054] Calcium acetate, tetrahydrofuran, and deionized water were mixed evenly at a ratio of 4g:8mL:20mL to obtain a calcium acetate solution.

[0055] Weigh out 100g of aminated boron nitride, 16g of hindered phenolic aromatic amide carboxylic acid ligand, and 800mL of N,N-dimethylformamide and add them to an argon-protected reaction flask. Stir the mixture and add 5.6g of N,N'-dicyclohexylcarbodiimide and 1.8g of N-hydroxysuccinimide to the reaction flask at room temperature. Keep the mixture warm for 6 hours and filter to obtain a filter cake.

[0056] Add the filter cake and 1200 mL of calcium acetate solution to a reaction flask and stir. Heat the reaction flask to 60 °C and stir for 4 h. Cool the reaction flask to room temperature, filter, wash the filter cake three times with purified water and dry it under vacuum. Transfer the filter cake to a drying oven at 70 °C and dry it to constant weight to obtain hindered phenolamine calcium coordination modified boron nitride.

[0057] In the reaction, the carboxyl group in the hindered phenolic aromatic amide carboxylic acid ligand is activated by N,N'-dicyclohexylcarbodiimide and N-hydroxysuccinimide, forming a reactive ester intermediate that readily reacts with amino groups. Subsequently, it undergoes an amidation reaction with the amino group on the surface of aminated boron nitride, covalently fixing the hindered phenolic aromatic amide carboxylic acid ligand to the boron nitride surface. During subsequent mixing with calcium acetate solution, the amidated or residual carboxyl group reacts with the Ca in the calcium acetate solution. 2+ The formation of calcium carboxylate coordination structures allows for the formation of functional shells containing hindered phenols, aromatic amides, and calcium coordination structures on the boron nitride surface. The immobilized hindered phenol structures continuously capture free radicals generated during thermo-oxidative aging, reducing oxidative breakage of polyolefin segments. The calcium coordination structures form charge-trapping sites at the filler interface, reducing free carrier mobility and increasing volume resistivity. The synergistic effect of the boron nitride layers and the calcium coordination interface reduces local electric field concentration and charge accumulation, thereby lowering the dielectric loss factor at 50 Hz and 1 MHz and improving the electrical performance stability after thermal aging.

[0058] Step 4: Preparation of reactive bridged polyolefins

[0059] Weigh out the following components by weight: 100 parts polypropylene, 1.2 parts 4-allyloxy-2-hydroxybenzophenone, 0.8 parts glycidyl methacrylate, and 0.05 parts dicumyl peroxide initiator. Mix them thoroughly and add them to a twin-screw extruder. Set the temperatures of the five temperature zones of the twin-screw extruder to 165℃, 175℃, 185℃, 190℃, and 190℃ respectively, and set the die head temperature to 190℃. Melt and mix for 60 seconds. After extrusion, cool and pelletize to obtain crude reactive bridged polyolefin.

[0060] The crude reactive bridged polyolefin and acetone were added to a reaction flask at a solid-liquid ratio of 1:7 and stirred. The reaction flask was heated to the point where the system was refluxed and extracted for 12 hours. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed three times with acetone and then transferred to a drying oven at 65°C. The oven was then evacuated to -0.09 MPa and dried under vacuum for 8 hours to obtain the reactive bridged polyolefin.

[0061] In the reaction, dicumyl peroxide decomposes at the melt extrusion temperature to generate free radicals, which then undergo a grafting reaction with 4-allyloxy-2-hydroxybenzophenone and glycidyl methacrylate, introducing benzophenone structures and epoxy groups onto the polypropylene segments. The benzophenone structure has a voltage stabilizing effect and can participate in the regulation of high-energy electrons, interfacial charges, and local electric fields, reducing the risk of electrical performance degradation of the material under electric field conditions. Glycidyl methacrylate provides epoxy groups, which can subsequently undergo ring-opening reactions with carboxyl, amino, or hydroxyl groups on the modified boron nitride surface. The polypropylene segments ensure good compatibility between this reactive bridging polyolefin and the polyolefin resin matrix. The role of acetone reflux extraction is to remove unreacted small molecule monomers, oligomers, and residual impurities, reducing the negative impact of free polar substances on media loss.

[0062] Step 5: Prepare low dielectric loss insulating granules

[0063] Hindered phenolamine calcium coordination modified boron nitride and reactive bridging polyolefin were placed in an internal mixer at a weight ratio of 1:7. The mixing temperature was set to 170℃ and the mixture was mixed for 6 minutes. After cooling, the mixture was pelletized to obtain the interfacial reaction masterbatch.

[0064] Weigh out the following components by weight: 70 parts polypropylene, 20 parts propylene-ethylene random copolymer, 18 parts ethylene-octene copolymer, and 5 parts maleic anhydride-grafted polypropylene. Mix them evenly to obtain a polyolefin resin matrix.

[0065] Antioxidant 168, calcium stearate, ethylene bis-stearamide and diisobutyl phthalate were mixed evenly in a weight ratio of 4:2:1:6 to obtain the additive.

[0066] Weigh out 100 parts by weight of polyolefin resin matrix, 12 parts by weight of interface reaction masterbatch, and 1 part by weight of additives. Mix them evenly and add them to a twin-screw extruder. Set the temperatures of the five temperature zones of the twin-screw extruder to 165℃, 175℃, 185℃, 190℃ and 190℃ respectively. Set the die head temperature to 190℃. Melt and mix for 40 seconds. After extrusion, cool and pelletize to obtain low dielectric loss insulating granules.

[0067] Step 6: Prepare the cable core

[0068] Several copper wires with a diameter of 2±0.2mm are twisted together to form a cable, resulting in a cross-sectional area of ​​100±5mm². 2 The conductor;

[0069] Low dielectric loss insulating granules are added to a single-screw extruder with a barrel temperature of 185℃ and a die temperature of 195℃. After melting and mixing for 60 seconds, the mixture is extruded and coated onto the outside of a conductor at 80℃. The material is then cooled in a 90℃ hot water bath for 30 seconds, followed by cooling and shaping in a 20℃ cold water bath. Finally, it is annealed at 115℃ for 15 minutes to form a low dielectric loss insulating layer with a thickness of 5±0.1mm on the outside of the conductor, thus obtaining the cable core.

[0070] Example 3

[0071] This embodiment provides a method for preparing a low dielectric loss insulated cable core, including the following steps:

[0072] Step 1: Preparation of hindered phenolic aromatic amide carboxylic acid ligands

[0073] Weigh out 59.4 g of 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride and 178.2 g of N,N-dimethylformamide, mix them evenly to obtain a 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride solution;

[0074] Weigh out 36.3 g of 5-aminoisophthalic acid, 327 mL of N,N-dimethylformamide, and 20 g of triethylamine and add them to an argon-protected reaction flask. Stir until the system dissolves. Cool the reaction flask to 3°C and add the prepared 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride solution dropwise to the reaction flask. After the addition is complete, heat the reaction flask to 60°C and keep it at this temperature for 5 h. Cool the reaction flask to room temperature and pour the reaction solution into a reaction flask containing 1 L of deionized water. Stir and disperse for 25 min, filter, wash the filter cake three times with deionized water, dry it under vacuum, and then transfer it to a drying oven at 65°C to dry to constant weight to obtain the hindered phenolic aromatic amide carboxylic acid ligand.

[0075] Step 2: Preparation of amino-modified boron nitride

[0076] Weigh 100g of nano boron nitride, 12g of γ-aminopropyltriethoxysilane, and 1000mL of anhydrous ethanol and add them to a reaction flask. Stir the mixture and add 70mL of 4.5mol / L sodium hydroxide solution to the reaction flask. Heat the reaction flask to 63℃ and keep it at that temperature for 5h. Cool the reaction flask to room temperature, filter the mixture, wash the filter cake with purified water until neutral, and then dry it under vacuum. Transfer the filter cake to a drying oven at 65℃ and dry it to constant weight to obtain amino boron nitride.

[0077] Step 3: Preparation of hindered phenolamine calcium coordination modified boron nitride

[0078] Calcium acetate, tetrahydrofuran, and deionized water were mixed evenly at a ratio of 4.5g:8mL:20mL to obtain a calcium acetate solution.

[0079] Weigh out 100g of aminated boron nitride, 18g of hindered phenolic aromatic amide carboxylic acid ligand, and 900mL of N,N-dimethylformamide and add them to an argon-protected reaction flask. Stir the mixture and add 6.0g of N,N'-dicyclohexylcarbodiimide and 2.2g of N-hydroxysuccinimide to the reaction flask at room temperature. Keep the mixture warm for 7 hours and filter to obtain a filter cake.

[0080] The filter cake was added to a reaction flask with 1200 mL of calcium acetate solution and stirred. The reaction flask was heated to 63 °C and stirred for 4.5 h. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed three times with purified water and then dried under vacuum. The filter cake was transferred to a drying oven at 75 °C and dried to constant weight to obtain hindered phenolamine calcium coordination modified boron nitride.

[0081] Step 4: Preparation of reactive bridged polyolefins

[0082] Weigh out the following components by weight: 100 parts polypropylene, 1.35 parts 4-allyloxy-2-hydroxybenzophenone, 0.9 parts glycidyl methacrylate, and 0.05 parts dicumyl peroxide initiator. Mix them thoroughly and add them to a twin-screw extruder. Set the temperatures of the five temperature zones of the twin-screw extruder to 165℃, 175℃, 185℃, 190℃, and 190℃ respectively, and set the die head temperature to 190℃. Melt and mix for 70 seconds. After extrusion, cool and pelletize to obtain crude reactive bridged polyolefin.

[0083] The crude reactive bridged polyolefin and acetone were added to a reaction flask at a solid-liquid ratio of 1:7.5 and stirred. The reaction flask was heated to the point where the system was refluxed and extracted for 12 hours. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed three times with acetone and then transferred to a drying oven at 70°C. The oven was then evacuated to -0.09 MPa and vacuum dried for 8.5 hours to obtain the reactive bridged polyolefin.

[0084] Step 5: Prepare low dielectric loss insulating granules

[0085] Hindered phenolamine calcium coordination modified boron nitride and reactive bridging polyolefin were placed in an internal mixer at a weight ratio of 1:7.5. The mixing temperature was set to 175℃ and the mixture was mixed for 7 minutes. After cooling, the mixture was pelletized to obtain the interfacial reaction masterbatch.

[0086] Weigh out the following components by weight: 75 parts polypropylene, 25 parts propylene-ethylene random copolymer, 20.5 parts ethylene-octene copolymer, and 6.5 parts maleic anhydride-grafted polypropylene. Mix them evenly to obtain a polyolefin resin matrix.

[0087] Antioxidant 168, calcium stearate, ethylene bis-stearamide and diisobutyl phthalate were mixed evenly in a weight ratio of 4:2:1:6 to obtain the additive.

[0088] Weigh out 100 parts by weight of polyolefin resin matrix, 14 parts by weight of interfacial reaction masterbatch, and 1 part by weight of additives. Mix them evenly and add them to a twin-screw extruder. Set the temperatures of the five temperature zones of the twin-screw extruder to 165℃, 175℃, 185℃, 190℃, and 190℃ respectively. Set the die head temperature to 190℃. Melt and mix for 50 seconds. After extrusion, cool and pelletize to obtain low dielectric loss insulating granules.

[0089] Step 6: Prepare the cable core

[0090] Several copper wires with a diameter of 2±0.2mm are twisted together to form a cable, resulting in a cross-sectional area of ​​100±5mm². 2 The conductor;

[0091] Low dielectric loss insulating granules are added to a single-screw extruder with a barrel temperature of 190℃ and a die temperature of 195℃. After melting and mixing for 70 seconds, the mixture is extruded and coated onto the outside of a conductor at a temperature of 85℃. The material is then cooled in a 90℃ hot water bath for 40 seconds, followed by cooling and shaping in a 23℃ cold water bath. Finally, it is annealed at 115℃ for 18 minutes to form a low dielectric loss insulating layer with a thickness of 5±0.1mm on the outside of the conductor, thus obtaining the cable core.

[0092] Example 4

[0093] This embodiment provides a method for preparing a low dielectric loss insulated cable core, including the following steps:

[0094] Step 1: Preparation of hindered phenolic aromatic amide carboxylic acid ligands

[0095] Weigh out 59.4 g of 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride and 178.2 g of N,N-dimethylformamide, mix them evenly to obtain a 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride solution;

[0096] Weigh out 36.3 g of 5-aminoisophthalic acid, 363 mL of N,N-dimethylformamide, and 21.8 g of triethylamine and add them to an argon-protected reaction flask. Stir until the system dissolves. Cool the reaction flask to 5 °C and add the prepared 3,5-bis(tert-butyl)-4-hydroxyphenylpropionyl chloride solution dropwise to the reaction flask. After the addition is complete, heat the reaction flask to 65 °C and keep it at this temperature for 6 h. Cool the reaction flask to room temperature and pour the reaction solution into a reaction flask containing 1 L of deionized water. Stir and disperse for 30 min, filter, wash the filter cake three times with deionized water, dry it under vacuum, and then transfer it to a drying oven at 70 °C to dry to constant weight to obtain the hindered phenolic aromatic amide carboxylic acid ligand.

[0097] Step 2: Preparation of amino-modified boron nitride

[0098] Weigh 100g of nano boron nitride, 14g of γ-aminopropyltriethoxysilane, and 1000mL of anhydrous ethanol and add them to a reaction flask. Stir the mixture and add 80mL of 5mol / L sodium hydroxide solution to the reaction flask. Heat the reaction flask to 65℃ and keep it at that temperature for 6h. Cool the reaction flask to room temperature, filter the mixture, wash the filter cake with purified water until neutral, and then dry it under vacuum. Transfer the filter cake to a drying oven at 70℃ and dry it to constant weight to obtain amino boron nitride.

[0099] Step 3: Preparation of hindered phenolamine calcium coordination modified boron nitride

[0100] Calcium acetate, tetrahydrofuran, and deionized water were mixed evenly at a ratio of 5g:8mL:20mL to obtain a calcium acetate solution.

[0101] Weigh out 100g of aminated boron nitride, 20g of hindered phenolic aromatic amide carboxylic acid ligand, and 1000mL of N,N-dimethylformamide and add them to an argon-protected reaction flask. Stir the mixture and add 6.4g of N,N'-dicyclohexylcarbodiimide and 2.6g of N-hydroxysuccinimide to the reaction flask at room temperature. Keep the mixture warm for 8 hours and filter to obtain a filter cake.

[0102] Add the filter cake and 1200 mL of calcium acetate solution to a reaction flask and stir. Heat the reaction flask to 65 °C and stir for 5 h. Cool the reaction flask to room temperature, filter, wash the filter cake three times with purified water and dry it under vacuum. Transfer the filter cake to a drying oven at 80 °C and dry it to constant weight to obtain hindered phenolamine calcium coordination modified boron nitride.

[0103] Step 4: Preparation of reactive bridged polyolefins

[0104] Weigh out the following components by weight: 100 parts polypropylene, 1.5 parts 4-allyloxy-2-hydroxybenzophenone, 1 part glycidyl methacrylate, and 0.05 parts dicumyl peroxide initiator. Mix them thoroughly and add them to a twin-screw extruder. Set the temperatures of the five temperature zones of the twin-screw extruder to 165℃, 175℃, 185℃, 190℃, and 190℃ respectively, and set the die head temperature to 190℃. Melt and mix for 80 seconds. After extrusion, cool and pelletize to obtain crude reactive bridged polyolefin.

[0105] The crude reactive bridged polyolefin and acetone were added to a reaction flask at a solid-liquid ratio of 1:8 and stirred. The reaction flask was heated to the point where the system was refluxed and extracted for 12 hours. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed three times with acetone and then transferred to a drying oven at 75°C. The oven was then evacuated to -0.09 MPa and dried under vacuum for 9 hours to obtain the reactive bridged polyolefin.

[0106] Step 5: Prepare low dielectric loss insulating granules

[0107] Hindered phenolamine calcium coordination modified boron nitride and reactive bridging polyolefin were placed in an internal mixer at a weight ratio of 1:8. The mixing temperature was set to 180℃ and the mixture was mixed for 8 minutes. After cooling, the mixture was pelletized to obtain the interfacial reaction masterbatch.

[0108] Weigh out the following components by weight: 80 parts polypropylene, 30 parts propylene-ethylene random copolymer, 23 parts ethylene-octene copolymer, and 8 parts maleic anhydride-grafted polypropylene. Mix them evenly to obtain a polyolefin resin matrix.

[0109] Antioxidant 168, calcium stearate, ethylene bis-stearamide, and diisobutyl phthalate were mixed evenly in a weight ratio of 4:2:1:6 to obtain the additive.

[0110] Weigh out 100 parts by weight of polyolefin resin matrix, 16 parts by weight of interface reaction masterbatch, and 1 part by weight of additives. Mix them evenly and add them to a twin-screw extruder. Set the temperatures of the five temperature zones of the twin-screw extruder to 165℃, 175℃, 185℃, 190℃ and 190℃ respectively. Set the die head temperature to 190℃. Melt and mix for 60 seconds. After extrusion, cool and pelletize to obtain low dielectric loss insulating granules.

[0111] Step 6: Prepare the cable core

[0112] Several copper wires with a diameter of 2±0.2mm are twisted together to form a cable, resulting in a cross-sectional area of ​​100±5mm². 2 The conductor;

[0113] Low dielectric loss insulating granules are added to a single-screw extruder with a barrel temperature of 195℃ and a die temperature of 195℃. After melting and mixing for 80 seconds, the mixture is extruded and coated onto the outside of a conductor at a temperature of 90℃. The material is then cooled in a 90℃ hot water bath for 50 seconds, followed by cooling and shaping in a 25℃ cold water bath. Finally, it is annealed at 115℃ for 20 minutes to form a low dielectric loss insulating layer with a thickness of 5±0.1mm on the outside of the conductor, thus obtaining the cable core.

[0114] Comparative Example 1

[0115] The difference between this comparative example and Example 4 is that, in step 3, deionized water is used instead of calcium acetate solution.

[0116] Comparative Example 2

[0117] The difference between this comparative example and Example 4 is that in step 3, the hindered phenolamine calcium coordination modified boron nitride in step 5 is replaced by a mixture of aminated boron nitride and hindered phenolic aromatic amide carboxylic acid ligand in a weight ratio of 5:1.

[0118] Comparative Example 3

[0119] The difference between this comparative example and Example 4 is that step 4 is omitted, and the reactive bridging polyolefin in step 5 is replaced with polypropylene in step 4.

[0120] Comparative Example 4

[0121] The difference between this comparative example and Example 4 is that the aminated boron nitride prepared in step 2 is used instead of the hindered phenolamine calcium coordination modified boron nitride in step 5.

[0122] Performance testing:

[0123] The dielectric loss factor of the low dielectric loss insulation layer of the cable cores prepared in Examples 2-4 and Comparative Examples 1-4 was determined under AC test power at 50 Hz and 1 MHz, in accordance with GB / T 31838.8-2024 "Dielectric and resistive properties of solid insulating materials - Part 8: Determination of dielectric properties (AC method) - Relative permittivity and dielectric loss factor (frequency 1 MHz ~ 300 MHz)" and GB / T 3048.11-2025 "Test methods for electrical properties of wires and cables - Part 11: Dielectric loss tangent test".

[0124] The volume resistivity of the low dielectric loss insulation layer of the cable cores prepared in Examples 2-4 and Comparative Examples 1-4 was determined in accordance with the standard GB / T 3048.5-2007 "Electrical Performance Test Methods for Wires and Cables - Part 5: Insulation Resistance Test".

[0125] The tracking resistance of the cable cores prepared in Examples 2-4 and Comparative Examples 1-4 was determined according to the standard GB / T 3048.7-2007 "Electrical Performance Test Methods for Wires and Cables - Part 7: Tracking Resistance Test". If the sample has any of the following conditions: surface burning, continuous arc between the high-voltage electrode and the grounding electrode, surface leakage current exceeding 10μA, or breakdown of the sample due to local corrosion of the insulation, it is considered unqualified; otherwise, it is considered qualified.

[0126] Referring to standard GB / T 2951.12-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 12: General Test Methods - Thermal Aging Test Method", the cable cores prepared in Examples 2-4 and Comparative Examples 1-4 were subjected to thermal oxidative aging in an air environment at 135±2℃ for 168 hours. The dielectric loss factor, tracking resistance, and elongation at break retention rate of the low dielectric loss insulation layer of the cable core were measured. The specific test data are shown in Table 1-2 below.

[0127] Table 1 - Performance test data of the samples before thermal aging

[0128] Table 2 - Performance test data of samples after thermal aging

[0129] Data Analysis:

[0130] Comparative analysis of the data in Tables 1-2 above shows that the volume resistivity of the cable core sample prepared by this invention reaches 6.2-6.8 × 10⁻⁶. 17 Before thermo-oxidative aging, the dielectric loss factor of the low-dielectric-loss insulation layer of the sample reached 4.1-4.3 × 10⁻¹⁰ Ω·cm under a 50Hz AC test power supply. -4 The dielectric loss factor reaches 0.9-1.1×10⁻⁶ under a 1MHz AC test power supply. -3 After thermo-oxidative aging, the dielectric loss factor of the low-dielectric-loss insulation layer of the sample reached 6.1-7.0×10⁻⁶ under a 50Hz AC test power supply. -4 The dielectric loss factor reaches 1.3-1.6×10⁻⁶ under a 1MHz AC test power supply. -3 The elongation at break retention rate reached 90.4-91.2%, and the electrical tracking resistance of the sample was qualified before and after heat aging.

[0131] In Comparative Example 1, after replacing the calcium acetate solution with deionized water, the hindered phenolic aromatic amide carboxylic acid ligands can still be fixed on the surface of aminated boron nitride through amide bonds, but cannot form a calcium carboxylate coordination structure. Due to the lack of charge trapping sites and crystallization regulation effects formed by the calcium coordination structure, the carrier migration suppression ability decreases, the volume resistivity is lower than that of the Example, the dielectric loss factor before and after aging is higher than that of the Example, and the tracking resistance and elongation at break retention rate also decrease after aging.

[0132] In Comparative Example 2, the aminated boron nitride and the hindered phenolic aromatic amide carboxylic acid ligand exist only in a physical mixture, lacking a covalently fixed structure and subsequent calcium coordination structure. The hindered phenolic ligand is more likely to migrate, aggregate, or exist as a free polar small molecule in the polyolefin matrix. Polar structures such as carboxyl, amide, and phenolic hydroxyl groups enhance interfacial polarization and dielectric loss. The volume resistivity of the comparative example decreased significantly, and the dielectric loss factor tanδ increased significantly. After thermo-oxidative aging, because the antioxidant structure cannot be stably confined at the boron nitride interface, the oxidative degradation of the material intensifies, the dielectric loss factor tanδ increases significantly, the elongation at break decreases, and the tracking resistance also deteriorates significantly.

[0133] In Comparative Example 3, after replacing the reactive bridging polyolefin with ordinary polypropylene, there was no bridging structure in the system that could undergo ring-opening reactions with the carboxyl, amino, or hydroxyl groups on the modified boron nitride surface. The polar structures such as amides and carboxylates on the modified boron nitride surface were more easily exposed directly in the polyolefin matrix, and the filler dispersion and interfacial bonding also decreased. The 1MHz high-frequency dielectric loss of the comparative example increased significantly, and the volume resistivity decreased. After thermal aging, the resistance to electrical tracking and the retention of elongation at break decreased due to interfacial debonding and the increase of micro-defects. This shows that reactive bridging polyolefin plays a key role in reducing interfacial polarization and enhancing interfacial stability.

[0134] In Comparative Example 4, after replacing the hindered phenolamine calcium coordination modified boron nitride with aminated boron nitride, the immobilized hindered phenolic structure, aromatic amide structure and calcium coordination structure were lacking. Due to the lack of continuous antioxidant and calcium coordination charge trapping effect, the polyolefin segments were more prone to oxidative breakage after thermo-oxidative aging and generated polar aging products such as carbonyl and hydroxyl groups. This resulted in a significant increase in the dielectric loss factor tanδ after aging, a significant decrease in the elongation at break retention rate, and a change in the tracking resistance from good before aging to significant instability after aging.

[0135] This invention describes a composite interface structure consisting of a boron nitride sheet, a hindered phenolic amide calcium coordination shell, and a polyolefin bridging layer. The boron nitride sheet is constructed on the surface of boron nitride. Benzophenone and epoxy groups are introduced onto the polypropylene chain via free radical grafting. The epoxy groups then react with the hindered phenolic amide calcium coordination modified boron nitride to form a polyolefin bridging layer. This structure confines the functions of anti-oxidation, charge trapping, voltage stabilization, interfacial compatibility, and polarity shielding within the filler interface region. This reduces interfacial polarization caused by direct exposure of polar groups while suppressing free carrier migration and local electric field distortion. Furthermore, the hindered phenolic amide and boron nitride sheet barrier enhance thermo-oxidative aging stability.

[0136] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A low-voltage power cable with low dielectric loss, comprising a plurality of cable cores and an outer sheath, characterized in that, The cable core includes a conductor and a low dielectric loss insulation layer covering the outside of the conductor; The low dielectric loss insulating layer comprises the following components by weight: 100 parts of polyolefin resin matrix, 12-16 parts of interface reaction masterbatch, and 1 part of additives. The polyolefin resin matrix comprises the following components by weight: 70-80 parts polypropylene, 20-30 parts propylene-ethylene random copolymer, 18-23 parts ethylene-octene copolymer, and 5-8 parts maleic anhydride-grafted polypropylene. The interfacial reaction masterbatch is composed of hindered phenolamine calcium coordination modified boron nitride and reactive bridging polyolefin in a weight ratio of 1:7-8.

2. The low-dielectric-loss low-voltage power cable according to claim 1, characterized in that, The conductor is formed by stranding several copper wires with a diameter of 2±0.2mm together, and has a cross-sectional area of ​​100±5mm². 2 .

3. The low-dielectric-loss low-voltage power cable according to claim 1, characterized in that, The method for preparing hindered phenolamine calcium coordination modified boron nitride is as follows: Boron nitride is surface activated to introduce reactive groups onto its surface. After preparing aminated boron nitride, an organic ligand containing hindered phenolic groups and carboxyl groups is grafted onto the aminated boron nitride to fix the organic ligand onto the surface of the boron nitride. Then, a calcium-containing compound is used to coordinate the grafted boron nitride to form a functional shell containing hindered phenolic groups and calcium coordination structure on the surface of the boron nitride, thus obtaining hindered phenolamine calcium coordination modified boron nitride.

4. A low-dielectric-loss low-voltage power cable according to claim 3, characterized in that, The organic ligand containing hindered phenolic and carboxyl groups is obtained by reacting an aromatic carboxylic acid compound containing amino or hydroxyl groups with an acylation reagent containing hindered phenolic groups.

5. A low-voltage power cable with low dielectric loss according to claim 1, characterized in that, The reactive bridging polyolefin is obtained by melt grafting reaction of polyolefin, unsaturated monomer containing voltage-stabilizing groups, unsaturated monomer containing reactive groups, and initiator.

6. A low-dielectric-loss low-voltage power cable according to claim 5, characterized in that, The polyolefin includes one or more of polypropylene, polyethylene, ethylene-α-olefin copolymer, propylene-α-olefin copolymer, and polyolefin elastomer; the unsaturated monomer containing voltage-stabilizing groups includes unsaturated monomers containing benzophenone groups; the unsaturated monomer containing reactive groups includes unsaturated monomers containing epoxy groups; the initiator includes organic peroxide initiators or azo initiators.

7. A low-dielectric-loss low-voltage power cable according to claim 3, characterized in that, The method for preparing aminated boron nitride is as follows: boron nitride, an aminosilane coupling agent, and an alcohol solvent are mixed and reacted under alkaline conditions to hydrolyze the aminosilane coupling agent and bind it to the surface of boron nitride, thereby obtaining aminated boron nitride.

8. A low-dielectric-loss low-voltage power cable according to claim 7, characterized in that, The aminosilane-containing coupling agent includes one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-β-aminoethyl-γ-aminopropyltrimethoxysilane.

9. A low-dielectric-loss low-voltage power cable according to claim 1, characterized in that, The method for preparing the cable core is as follows: S1. Hindered phenolamine calcium coordination modified boron nitride and reactive bridging polyolefin are placed in an internal mixer, mixed and then pelletized to obtain interfacial reaction masterbatch. S2. After uniformly mixing the polyolefin resin matrix, interfacial reaction masterbatch, and additives, place them in a twin-screw extruder, melt-mix and extrude, cool and pelletize to obtain low dielectric loss insulating granules. S3. Place the low dielectric loss insulating granules in a single screw extruder and melt-extrude them to coat the outside of the conductor, forming a low dielectric loss insulating layer with a thickness of 5±0.1mm, thus obtaining the cable core.

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