Cross-linked polyethylene insulated flame-retardant power cable and preparation method thereof

Abstract

The invention relates to the technical field of power cables, in particular to a cross-linked polyethylene insulated flame-retardant power cable and a preparation method thereof, which are used for solving the problems that an existing cable material is extremely easy to damage when facing high temperature and flame, so that a cable insulating layer is exposed, and potential safety hazards exist. According to the insulating layer of the cable, the inner protection layer and the insulating flame-retardant layer are adopted for synergistic effect, the inner protection layer ensures basic electrical insulation and mechanical protection, and the insulating flame-retardant layer serves as an independent functional unit and is filled with a flame retardant, so that the cable has good insulating flame-retardant performance; a multi-layer and active fireproof system is constructed: a multi-layer and synergistic flame-retardant barrier is formed inside the cable by inner and outer modified base materials and a flame retardant in the insulating layer, so that the cable can be quickly self-extinguished during combustion, smoke and molten drops are remarkably inhibited, chemical crosslinking is completed between the inner protective layer and the insulating flame-retardant layer by adopting co-extrusion and synchronous crosslinking processes, an interlayer interface is eliminated, and the flame-retardant performance of the cable is improved; the structural integrity is improved, and the performance is improved.

Description

A cross-linked polyethylene insulated flame-retardant power cable and its preparation method Technical Field

[0001] This invention relates to the field of power cable technology, specifically to a cross-linked polyethylene insulated flame-retardant power cable and its preparation method. Background Technology

[0002] Power cables are a critical facility widely used in construction, industry, and transportation. To ensure the safety and reliability of power transmission, cables need to have good insulation and flame-retardant properties. With the development of power systems and the increasingly widespread application of electrical equipment, the demand for power cables is also increasing. Power cables are mainly used to transmit electricity. Due to their diverse installation locations, they face various environmental conditions. Among them, the cable sheath is an important component of the cable, mainly responsible for protecting the internal insulation layer of the cable from the influence of the external environment, such as mechanical damage, chemical corrosion, and combustion.

[0003] Traditional cables are made of basic rubber or PVC materials. While these materials offer some protection, they are easily damaged by high temperatures, flames, and certain chemicals, leading to exposed cable insulation and posing serious safety hazards.

[0004] Therefore, the cross-linked polyethylene insulated flame-retardant power cable and its preparation method of the present invention are of great significance in the field of power cable technology. Summary of the Invention

[0005] In order to overcome the above-mentioned technical problems, the present invention aims to provide a cross-linked polyethylene insulated flame-retardant power cable and its preparation method, which solves the problem that existing cable materials are easily damaged when exposed to high temperature and flame, resulting in exposed cable insulation layer and safety hazards.

[0006] The objective of this invention can be achieved through the following technical solution: Firstly, this application provides a cross-linked polyethylene insulated flame-retardant power cable, comprising, from the inside out, a cable core, an insulating flame-retardant layer, a metal shielding layer, and an outer sheath: wherein the cable core consists of a conductor and an inner sheath covering the conductor, the conductor diameter is 3.5-3.6 mm, and the thickness of the inner sheath is 1-1.2 mm; the conductor is a copper conductor; the raw material of the inner sheath is a modified base material; the raw material of the insulating flame-retardant layer is a modified base material and a flame retardant, and the thickness of the insulating flame-retardant layer is 1-1.2 mm; the metal shielding layer is an aluminum alloy wire mesh structure, woven from aluminum alloy wire AA8030 with a single filament diameter of 0.3-0.4 mm, and a thickness of 0.6-0.8 mm; the raw material of the outer sheath is polyethylene LD608, and the thickness of the outer sheath is 1.6-1.8 mm.

[0007] As a preferred embodiment of the present invention, the modified base material is prepared by the following steps: Step a1: Eugenol, the first part of acetonitrile, and anhydrous potassium carbonate are added to a three-necked flask equipped with a stirrer and a thermometer, nitrogen gas is introduced for protection, and the mixture is stirred for 30 min for later use; hexachlorocyclotriphosphazene and the second part of acetonitrile are added to a beaker, stirred for 30 min, and then added to the above three-necked flask. The mixture is stirred and reacted at 85°C for 48 h. After the reaction is completed, the mixture is filtered to remove the filter residue. The filtrate is evaporated using a rotary evaporator and transferred to a round-bottom flask. Anhydrous ethanol is added, and the mixture is allowed to stand for 12 h. The mixture is then filtered, and the filter cake is placed in a vacuum drying oven at 60°C for 6-12 h to obtain the functional filler; Step a2 Low-density polyethylene, ethylene-vinyl acetate resin, ethylene propylene diene monomer (EPDM) rubber, and polyolefin elastomer are added to a two-roll mill. The roll temperature is 110℃, the roll gap is 2-3mm, and the mixture is mixed for 10-15 minutes. Aluminum hydroxide, functional fillers, antioxidants, lubricants, and plasticizers are added, and the mixture is further mixed for 5-10 minutes. Peroxide crosslinking agents and co-crosslinking agents are added, the roll gap is adjusted to 1-2mm, and the mixture is further mixed for 30 minutes. The mixture is then transferred to a flat vulcanizing machine and heated at 180℃ and 5MPa for 3-5 minutes. The pressure is increased to 13MPa, and the mixture is held at 180℃ for 15 minutes. The mixture is then transferred to a cold press and cooled to 25℃ at 10-15MPa to obtain the modified base material.

[0008] In a preferred embodiment of the present invention, the ratio of eugenol, total acetonitrile, anhydrous potassium carbonate, hexachlorocyclotriphosphazene, and anhydrous ethanol in step a1 is 10-15 mL: 200 mL: 9-12 g: 7-8 g: 100 mL; the first part of acetonitrile accounts for 3 / 5 of the total acetonitrile; and the second part of acetonitrile accounts for 2 / 5 of the total acetonitrile.

[0009] In a preferred embodiment of the present invention, the ratio of the low-density polyethylene, ethylene-vinyl acetate resin, ethylene propylene diene monomer (EPDM) rubber, polyolefin elastomer, aluminum hydroxide, functional filler, antioxidant, lubricant, plasticizer, peroxide crosslinking agent, and co-crosslinking agent in step a2 is 50-60g: 20-25g: 15-20g: 10-13g: 100-130g: 10-12g: 1-2g: 1-3g: 3-5g: 2-5g: 1-3g; the low-density polyethylene is of type 2102N3W; the ethylene-vinyl acetate resin is of type 53007; and the polyolefin elastomer is of type POE. C0570; the antioxidant is a mixture of antioxidant 1010 and antioxidant didodecane thiodipropionate in a mass ratio of 2:1; the lubricant is zinc stearate; the plasticizer is dibutyl phthalate; the peroxide crosslinking agent is dicumyl peroxide; and the co-crosslinking agent is triallyl isocyanurate.

[0010] In a preferred embodiment of the present invention, the flame retardant is prepared by the following steps: Step b1: Attapulgite and the first part of deionized water are added to a three-necked flask equipped with a stirrer and a thermometer, and ultrasonically dispersed for 30-40 min to obtain a suspension; zinc acetate and the second part of deionized water are added to a beaker, and mixed and stirred for 10-15 min to obtain solution A; sodium hydroxide and the third part of deionized water are added to a beaker, and mixed and stirred for 10-15 min to obtain solution B; crystalline tin tetrachloride and the fourth part of deionized water are added to a beaker, and mixed and stirred for 10-15 min to obtain solution C; solutions A and C are added dropwise to the suspension at a rate of 1-2 mL / min, and mixed and stirred for 16 h; solution B is added, and stirring is continued for 30 min; the mixture is transferred to a reaction vessel, and hydrothermally reacted at 160°C for 12-16 h; the mixture is then naturally cooled to 25°C, allowed to stand for 12 h, filtered, and the filter cake is washed with distilled water and anhydrous ethanol, respectively. -3 times, vacuum dried at 60℃ for 24h, ball milled for 1-2h at 300-400r / min and ball-to-material ratio of 10:1, and sieved through a 200-300 mesh sieve to obtain the intermediate product; Step b2: Add boric acid and deionized water to a three-necked flask equipped with a stirrer and thermometer, and magnetically stir at 200r / min for 30min in a 95℃ oil bath. Add zinc oxide and attapulgite, and continue stirring and reacting for 6-8h. After completion, filter the cake and wash it 2-3 times with distilled water. Dry it under vacuum at 60℃ for 12 hours. Then, ball mill it for 1-2 hours at a speed of 300-400 r / min and a ball-to-material ratio of 10:1. Sieve the cake through a 200-300 mesh sieve to obtain the base material. Add the base material and intermediate product to a planetary ball mill at a ball-to-material ratio of 5-10:1 and a speed of 300-400 r / min for 1-2 hours. Sieve the cake through a 200 mesh sieve to obtain the flame retardant.

[0011] In a preferred embodiment of the present invention, the ratio of attapulgite, total deionized water, zinc acetate, sodium hydroxide, and crystalline tin tetrachloride in step b1 is 5-8g:400mL:3-4g:4-5g:5-6g; the first part of deionized water accounts for 1 / 4 of the total deionized water; the second part of deionized water accounts for 1 / 4 of the total deionized water; the third part of deionized water accounts for 1 / 4 of the total deionized water; and the fourth part of deionized water accounts for 1 / 4 of the total deionized water.

[0012] In a preferred embodiment of the present invention, the ratio of boric acid, deionized water, zinc oxide, attapulgite, and intermediate product in step b2 is 15-18g: 50mL: 4.5-5.5g: 12-13g: 10g.

[0013] Secondly, this application provides a method for preparing a cross-linked polyethylene insulated flame-retardant power cable, comprising the following steps: Step 1: Weighing 80-100 parts by weight of conductor, 70-80 parts by weight of modified base material, 10-15 parts by weight of flame retardant, 15-20 parts by weight of aluminum alloy wire AA8030 and 45-50 parts by weight of polyethylene LD608; Step 2: Laying out the conductor, heating it to 80-100℃ using a preheater, and co-extruding cross-linking, extruding half of the total amount of modified base material through a first extruder to form an inner sheath; and then extruding the remaining half of the total amount of modified base material over the conductor to form an inner sheath. The base material and flame retardant of component 2 are mixed in a side feeder and extruded over the inner sheath through a second extruder to form an insulating and flame-retardant layer. The mixture is then added to a vulcanizing tube and cross-linked under a nitrogen atmosphere of 180-200℃ and 0.8-1.2MPa. After natural cooling to 25℃, aluminum alloy wire AA8030 is braided over the insulating and flame-retardant layer with a coverage rate of ≥80% through a high-speed braiding machine to form a metal shielding layer. Polyethylene LD608 is extruded over the metal shielding layer through a third extruder and then cooled and shaped in a water tank to obtain a cross-linked polyethylene insulating flame-retardant power cable.

[0014] The beneficial effects of this invention: This invention provides a cross-linked polyethylene insulated flame-retardant power cable and its preparation method. The method involves laying out the conductor, preheating, and co-extruding cross-linking to extrude a portion of the modified base material onto the conductor to form an inner sheath. The remaining modified base material is mixed with a flame retardant in a side feeder and extruded onto the inner sheath to form an insulating and flame-retardant layer. This mixture is then added to a vulcanizing tube, cross-linked, cooled, and woven with AA8030 aluminum alloy wire onto the insulating and flame-retardant layer using a high-speed braiding machine to form a metal shielding layer. Finally, polyethylene is extruded onto the metal shielding layer, cooled, and shaped to obtain the cross-linked polyethylene insulated flame-retardant power cable. This cable will... Traditional single insulation layers are split into an inner sheath and an insulating flame-retardant layer. The inner sheath ensures basic electrical insulation and mechanical protection; the insulating flame-retardant layer, as an independent functional unit, is filled with flame retardant and has good insulating and flame-retardant properties. A multi-layered, active fire protection system is constructed: the modified base materials of the inner and outer layers and the flame retardant in the insulation layer form a multi-layered, synergistic flame-retardant barrier inside the cable, enabling the cable to self-extinguish quickly during combustion and significantly suppress smoke and molten droplets. Co-extrusion and synchronous cross-linking processes are used to form the inner sheath and the insulating flame-retardant layer in a molten state and complete chemical cross-linking in one step, eliminating interlayer interfaces, achieving seamless bonding, improving the overall structural integrity, and avoiding performance degradation caused by interlayer peeling.

[0015] In the preparation of cross-linked polyethylene insulated flame-retardant power cables, a modified base material was first prepared. Under alkaline catalyst and anhydrous potassium carbonate conditions, eugenol provided phenolic hydroxyl groups, which reacted with hexachlorocyclotriphosphazene provided active chlorine atoms. The phenolic hydroxyl groups of eugenol attacked and replaced the chlorine atoms on hexachlorocyclotriphosphazene, forming POC bonds. The eugenol structure was then grafted onto the cyclic phosphazene skeleton to obtain a functional filler. As a molecular-level flame retardant, the functional filler, during combustion, promotes polymer charring, forming a dense, heat-insulating char layer. Simultaneously, it decomposes to produce non-flammable gases, diluting oxygen and combustibles, resulting in excellent flame-retardant effects. In a two-roll mill, low-density... Polyethylene, ethylene-vinyl acetate, EPDM rubber, and polyolefin elastomers are melted and mixed under heat and shear stress to form a polymer blend matrix. Aluminum hydroxide and functional fillers are added as fillers and dispersed within the matrix. Under the high temperature and pressure of a flat vulcanizing machine, dicumyl peroxide decomposes to generate free radicals, which abstract hydrogen atoms from the polymer molecular chains, producing polymer chain free radicals. With the bridging of a crosslinking agent, these free radicals combine and crosslink to obtain a modified matrix. The blend of multiple polymers forms a rigid-flexible phase-separated matrix. Low-density polyethylene provides strength, EPDM / polyolefin elastomer provides elasticity, and peroxide-induced chemical crosslinking... A robust three-dimensional network is formed, giving the material high strength while absorbing and dispersing impact energy, exhibiting good toughness and crack resistance. The peroxide crosslinking agent decomposes upon heating, generating highly reactive free radicals that abstract hydrogen atoms from the main chains of polymers such as polyethylene and EPDM rubber, generating polymer chain free radicals. These free radicals then combine to form C-C crosslinking bonds, constituting a three-dimensional network. Compared to abstracting hydrogen from saturated polymer chains, the alkenyl groups of the functional filler more readily add to the double bonds of the alkenyl groups, becoming part of the crosslinking network through covalent bonds. This prevents the filler from agglomerating due to migration or phase separation, ensuring its flame-retardant and reinforcing effects. The phosphazene ring structure itself has extremely high thermal stability. During combustion, these nodes can catalyze the dehydration and cyclization of the surrounding polymer chains, significantly promoting the formation of a dense, highly graphitized char layer and improving the flame retardant efficiency of the condensed phase. The flame retardant elements (P, N) are fixed in the network by chemical bonds and will not be precipitated, migrated or lost during processing or use, ensuring the durability of the flame retardant performance. The functional filler has good compatibility with the organic long chains of the polymer matrix and is evenly dispersed, ensuring melt flowability and extrusion surface smoothness. After the chemical cross-linking network is formed, the material is dimensionally stable during subsequent high-temperature processing and use, and has strong resistance to creep and heat deformation.

[0016] In the preparation of cross-linked polyethylene insulated flame-retardant power cables, a flame retardant was first prepared using porous mineral attapulgite as a carrier. The attapulgite was dispersed in water to form a suspension. Solutions of zinc acetate and crystalline tin tetrachloride were then added dropwise. Zinc and tin ions were adsorbed onto the surface and pores of the attapulgite. Upon addition of sodium hydroxide solution, a co-precipitation reaction occurred, generating zinc and tin hydroxides that adhered to the carrier. Through a hydrothermal reaction, the hydroxides were dehydrated and crystallized under high temperature and pressure, transforming into stable zinc oxide and tin oxide, which firmly bonded to the attapulgite, yielding an intermediate product. Attapulgite provides a large specific surface area and stability, preventing the agglomeration of oxide nanoparticles and fully exposing their catalytic active sites. Boric acid was reacted with zinc oxide under hydrothermal conditions to generate zinc borate, which combined with the simultaneously added attapulgite to form a substrate. The substrate and the intermediate product were then physically compounded through ball milling to obtain the flame retardant. The components of the flame retardant play different but complementary roles under high fire temperatures, forming a catalytic effect. The synergistic effect of char formation, skeletal support, and glass coating, with nano-zinc tin oxide acting as a highly efficient catalyst, accelerates the dehydrogenation, cross-linking, and aromatization reactions of the polymer during thermal decomposition, promoting the rapid formation of a dense, continuous, and robust expanded char layer in the insulation material. Attapulgite / attapulgite, as inorganic minerals, are non-flammable and heat-resistant, embedding themselves in the polymer matrix and the formed char layer, significantly enhancing the mechanical strength, density, and thermal stability of the char layer, preventing it from cracking or peeling under flame impact or airflow. Zinc borate decomposes thermally, producing a glassy melt of boron oxide, which flows and covers the char layer and the unburned polymer surface, further isolating oxygen and heat, and sealing cracks. The synergistic effect of these multiple flame-retardant mechanisms allows the cable insulation layer to quickly form a robust heat and oxygen barrier when in contact with flames, greatly delaying the thermal decomposition of internal materials, giving the cable excellent self-extinguishing and flame-retardant capabilities. Nanoscale dispersed oxides and micron-scale mineral fillers play a reinforcing and toughening role in the polymer matrix. They can transfer and disperse stress, inhibiting crack propagation. Attached Figure Description

[0017] The invention will now be further described with reference to the accompanying drawings.

[0018] Figure 1 is a schematic diagram of the cross-linked polyethylene insulated flame-retardant power cable of Embodiments 1-3 of the present invention.

[0019] Figure 2 is a schematic diagram of the oxygen index test results of the flame-retardant insulation layer in the cross-linked polyethylene insulated flame-retardant power cables of Examples 1-3 and Comparative Examples 1-3 of the present invention.

[0020] Figure 3 is a schematic diagram of the tensile strength test results of the flame-retardant insulation layer in the cross-linked polyethylene insulated flame-retardant power cables of Examples 1-3 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Embodiments

[0022] Please refer to Figure 1. This embodiment is a method for preparing a cross-linked polyethylene insulated flame-retardant power cable, including the following steps: Step S1: Add 10 mL of eugenol, 120 mL of acetonitrile, and 9 g of anhydrous potassium carbonate to a three-necked flask equipped with a stirrer and thermometer, purge with nitrogen for protection, mix and stir for 30 min, and set aside; Add 7 g of hexachlorocyclotriphosphazene and 80 mL of acetonitrile to a beaker, mix and stir for 30 min, add to the above three-necked flask, mix and stir at 85 °C for 48 h, filter after the reaction is complete, remove the filter residue, evaporate the filtrate using a rotary evaporator, transfer to a round-bottom flask, add 100 mL of anhydrous ethanol, let stand for 12 h, filter, place the filter cake in a vacuum drying oven at 60 °C for 6 h to obtain the functional filler; Step S2: Add 50 g of low-density polyethylene 2102N3W, 20 g of ethylene-vinyl acetate resin 53007, 15 g of ethylene propylene diene monomer (EPDM) rubber, and 10 g of polyolefin elastomer (POE) C0570 was added to a two-roll open mill at a roll temperature of 110°C and a roll gap of 2 mm. The mixture was kneaded for 10 minutes. Then, 100 g of aluminum hydroxide, 10 g of functional filler, 1 g of antioxidant, 1 g of zinc stearate, and 3 g of dibutyl phthalate were added. The mixture was kneaded for another 5 minutes. Next, 2 g of dicumyl peroxide and 1 g of triallyl isocyanurate were added. The roll gap was adjusted to 1 mm, and the mixture was kneaded for another 30 minutes. The mixture was then transferred to a flat vulcanizing press and heated at 180°C and 5 MPa for 3 minutes, increasing the pressure to 13 MPa. Pa, the reaction was carried out at 180℃ for 15 min, then transferred to a cold press and cooled to 25℃ at 10 MPa to obtain the modified base material; the antioxidant was prepared by mixing antioxidant 1010 and antioxidant didodecane thiodipropionate at a mass ratio of 2:1; Step S3: 5g of attapulgite and 100mL of deionized water were added to a three-necked flask equipped with a stirrer and a thermometer, and ultrasonically dispersed for 30 min to obtain a suspension; 3g of zinc acetate and 100mL of deionized water were added to a beaker and mixed. Stir for 10 min to obtain solution A; add 4 g sodium hydroxide and 100 mL deionized water to a beaker, mix and stir for 10 min to obtain solution B; add 5 g crystalline tin tetrachloride and 100 mL deionized water to a beaker, mix and stir for 10 min to obtain solution C; add solutions A and C dropwise to the suspension at a rate of 1 mL / min, mix and stir for 16 h, add solution B, continue stirring for 30 min, transfer to a reaction vessel, and hydrothermally react at 160 °C for 12 h. The mixture was naturally cooled to 25°C, allowed to stand for 12 hours, filtered, and the filter cake was washed twice with distilled water and anhydrous ethanol, respectively. It was then vacuum dried at 60°C for 24 hours, ball-milled for 1 hour at 300 r / min and a ball-to-material ratio of 10:1, and sieved through a 200-mesh sieve to obtain the intermediate product. Step S4: 15 g of boric acid and 50 mL of deionized water were added to a three-necked flask equipped with a stirrer and thermometer. The mixture was magnetically stirred at 200 r / min for 30 minutes in a 95°C oil bath. 4...5g zinc oxide and 12g attapulgite clay were stirred and reacted for 6 hours. After the reaction was completed, the mixture was filtered, and the filter cake was washed twice with distilled water and dried under vacuum at 60℃ for 12 hours. It was then ball-milled for 1 hour at a speed of 300 r / min and a ball-to-material ratio of 10:1. The mixture was sieved through a 200-mesh sieve to obtain the base material. The base material and 10g of intermediate product were added to a planetary ball mill at a ball-to-material ratio of 5:1 and a speed of 300 r / min for 1 hour. The mixture was then sieved through a 200-mesh sieve to obtain the flame retardant. Step S5: 80 parts by weight of copper conductor, 70 parts by weight of modified base material, 10 parts by weight of flame retardant, 15 parts by weight of aluminum alloy wire AA8030, and 45 parts by weight of polyethylene LD608 were weighed. Step S6: The copper conductor was laid out and passed through… The preheater heats the material to 80°C. Co-extrusion cross-linking is used, with half of the total modified base material extruded through a first extruder and wrapped around the copper conductor to form the inner sheath. The remaining half of the modified base material is mixed with a flame retardant in a side feeder and extruded through a second extruder around the inner sheath to form an insulating and flame-retardant layer. This layer is then added to a vulcanizing tube and cross-linked at 180°C and 0.8MPa nitrogen atmosphere. After natural cooling to 25°C, aluminum alloy wire AA8030 is braided with a coverage rate of ≥80% around the insulating and flame-retardant layer using a high-speed braiding machine to form a metal shielding layer. Polyethylene LD608 is extruded through a third extruder around the metal shielding layer and then cooled and shaped in a water bath to obtain a cross-linked polyethylene insulated flame-retardant power cable. Example.

[0023] Please refer to Figure 1. This embodiment is a method for preparing a cross-linked polyethylene insulated flame-retardant power cable, including the following steps: Step S1: Add 13 mL of eugenol, 120 mL of acetonitrile, and 11 g of anhydrous potassium carbonate to a three-necked flask equipped with a stirrer and thermometer, purge with nitrogen for protection, mix and stir for 30 min, and set aside; Add 7.5 g of hexachlorocyclotriphosphazene and 80 mL of acetonitrile to a beaker, mix and stir for 30 min, then add to the above three-necked flask, and heat at 85°C. The mixture was stirred and reacted at ℃ for 48 h. After the reaction was completed, it was filtered to remove the filter residue. The filtrate was evaporated using a rotary evaporator and transferred to a round-bottom flask. 100 mL of anhydrous ethanol was added, and the mixture was allowed to stand for 12 h. The mixture was then filtered, and the filter cake was placed in a vacuum drying oven at 60 ℃ and dried for 9 h to obtain the functional filler. Step S2: 55 g of low-density polyethylene 2102N3W, 23 g of ethylene-vinyl acetate resin 53007, 18 g of ethylene propylene diene monomer (EPDM) rubber, and 12 g of polyolefin elastomer (POE) were mixed and stirred. C0570 was added to a two-roll open mill at a roll temperature of 110°C and a roll gap of 2 mm. The mixture was kneaded for 13 minutes. Then, 115 g of aluminum hydroxide, 11 g of functional filler, 1.5 g of antioxidant, 2 g of zinc stearate, and 4 g of dibutyl phthalate were added. The mixture was kneaded for another 8 minutes. Then, 4 g of dicumyl peroxide and 2 g of triallyl isocyanurate were added. The roll gap was adjusted to 1 mm, and the mixture was kneaded for another 30 minutes. The mixture was then transferred to a flat vulcanizing mill and kneaded at 18... Heating at 0℃ and 5MPa for 4 minutes, then increasing the pressure to 13MPa, and maintaining the pressure at 180℃ for 15 minutes, the mixture is transferred to a cold press and cooled to 25℃ at 13MPa to obtain the modified base material; the antioxidant is composed of antioxidant 1010 and antioxidant didodecane thiodipropionate in a mass ratio of 2:1; Step S3: 7g of attapulgite and 100mL of deionized water are added to a three-necked flask equipped with a stirrer and a thermometer. In a 1-5 mol / L container, the mixture was ultrasonically dispersed for 35 min to obtain a suspension. 3.5 g of zinc acetate and 100 mL of deionized water were added to a beaker and stirred for 13 min to obtain solution A. 4.5 g of sodium hydroxide and 100 mL of deionized water were added to a beaker and stirred for 13 min to obtain solution B. 5.5 g of crystalline tin tetrachloride and 100 mL of deionized water were added to a beaker and stirred for 13 min to obtain solution C. Solutions A and C were added dropwise to the suspension at a rate of 1.5 mL / min, and the mixture was stirred for 16 h. Solution B was then added, and stirring continued for 30 min. The mixture was transferred to a reaction vessel and hydrothermally reacted at 160 °C for 14 h. After natural cooling to 25 °C, the mixture was allowed to stand for 12 h, filtered, and the filter cake was washed three times with distilled water and anhydrous ethanol, respectively. The cake was then vacuum dried at 60 °C for 24 h and ball-milled at a speed of 350 r / min and a ball-to-material ratio of 10:1.After 5 hours, the intermediate product was obtained by sieving through a 250-mesh sieve. Step S4: 17g of boric acid and 50mL of deionized water were added to a three-necked flask equipped with a stirrer and thermometer. The mixture was magnetically stirred at 200r / min for 30 minutes in an oil bath at 95℃. 5g of zinc oxide and 12.5g of attapulgite were added, and the reaction was continued for 7 hours. After the reaction was completed, the mixture was filtered, and the filter cake was washed three times with distilled water. It was then vacuum dried at 60℃ for 12 hours and ball-milled for 1.5 hours at a speed of 350r / min and a ball-to-material ratio of 10:1. The mixture was then sieved through a 250-mesh sieve to obtain the base material. The base material and 10g of the intermediate product were added to a planetary ball mill at a ball-to-material ratio of 8:1 and a speed of 350r / min for 1.5 hours. The mixture was then sieved through a 200-mesh sieve to obtain the flame retardant. Step S5: 90 parts by weight of copper conductor and 75 parts by weight of modified... The components are: base material, 13 parts flame retardant, 18 parts aluminum alloy wire AA8030, and 48 parts polyethylene LD608; Step S6: The copper conductor is laid out and heated to 90°C using a preheater. Half of the modified base material is extruded over the copper conductor using a first extruder to form an inner sheath. The remaining half of the modified base material is mixed with the flame retardant in a side feeder and extruded over the inner sheath using a second extruder to form an insulating flame-retardant layer. This is added to a vulcanizing tube and cross-linked under nitrogen at 190°C and 1MPa. After natural cooling to 25°C, the aluminum alloy wire AA8030 is braided over the insulating flame-retardant layer with a coverage rate of ≥80% using a high-speed braiding machine to form a metal shielding layer. The polyethylene LD608 is extruded over the metal shielding layer using a third extruder and then cooled and shaped in a water bath to obtain a cross-linked polyethylene insulated flame-retardant power cable. Example.

[0024] Please refer to Figure 1. This embodiment is a method for preparing a cross-linked polyethylene insulated flame-retardant power cable, including the following steps: Step S1: Add 15 mL of eugenol, 120 mL of acetonitrile, and 12 g of anhydrous potassium carbonate to a three-necked flask equipped with a stirrer and thermometer, purge with nitrogen for protection, mix and stir for 30 min, and set aside; Add 8 g of hexachlorocyclotriphosphazene and 80 mL of acetonitrile to a beaker, mix and stir for 30 min, add to the above three-necked flask, mix and stir at 85 °C for 48 h, filter after the reaction is complete, remove the filter residue, evaporate the filtrate using a rotary evaporator, transfer to a round-bottom flask, add 100 mL of anhydrous ethanol, let stand for 12 h, filter, place the filter cake in a vacuum drying oven at 60 °C for 12 h to obtain the functional filler; Step S2: Add 60 g of low-density polyethylene 2102N3W, 25 g of ethylene-vinyl acetate resin 53007, 20 g of ethylene propylene diene monomer (EPDM) rubber, and 13 g of polyolefin elastomer (POE) C0570 was added to a two-roll open mill at a roll temperature of 110°C and a roll gap of 3mm. The mixture was kneaded for 15 minutes. Then, 130g of aluminum hydroxide, 12g of functional filler, 2g of antioxidant, 3g of zinc stearate, and 5g of dibutyl phthalate were added. The mixture was kneaded for another 10 minutes. Next, 5g of dicumyl peroxide and 3g of triallyl isocyanurate were added. The roll gap was adjusted to 2mm, and the mixture was kneaded for another 30 minutes. The mixture was then transferred to a flat vulcanizing mill and kneaded at 180°C for 5 minutes. Heating at MPa for 5 min, increasing the pressure to 13 MPa, and holding the reaction at 180℃ for 15 min, then transferring to a cold press and cooling at 15 MPa to 25℃ to obtain the modified base material; the antioxidant is composed of antioxidant 1010 and antioxidant didodecane thiodipropionate in a mass ratio of 2:1; Step S3: 8 g of attapulgite and 100 mL of deionized water are added to a three-necked flask equipped with a stirrer and a thermometer, and ultrasonically dispersed. After 40 min, a suspension was obtained. 4 g of zinc acetate and 100 mL of deionized water were added to a beaker and stirred for 15 min to obtain solution A. 5 g of sodium hydroxide and 100 mL of deionized water were added to a beaker and stirred for 15 min to obtain solution B. 6 g of crystalline tin tetrachloride and 100 mL of deionized water were added to a beaker and stirred for 15 min to obtain solution C. Solutions A and C were added dropwise to the suspension at a rate of 2 mL / min, and the mixture was stirred for 16 h. Solution B was added, and stirring continued for 30 min. The mixture was then transferred to a reaction vessel and subjected to hydrothermal reaction at 160℃ for 16 h. After natural cooling to 25℃, the mixture was allowed to stand for 12 h, filtered, and the filter cake was washed three times with distilled water and anhydrous ethanol, respectively. The cake was then vacuum dried at 60℃ for 24 h, ball-milled for 2 h at a speed of 400 r / min and a ball-to-material ratio of 10:1, and sieved through a 300-mesh sieve to obtain the intermediate product.Step S4: Add 18g boric acid and 50mL deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir magnetically at 200r / min for 30min in a 95℃ oil bath. Add 5.5g zinc oxide and 13g attapulgite clay, and continue stirring for 8h. After the reaction is complete, filter the mixture. Wash the filter cake three times with distilled water and vacuum dry at 60℃ for 12h. Ball mill at 400r / min and a ball-to-material ratio of 10:1 for 2h. Sieve through a 300-mesh sieve to obtain the substrate. Add the substrate and 10g of intermediate product to a planetary ball mill at a ball-to-material ratio of 10:1 and a speed of 400r / min for 2h. Sieve through a 200-mesh sieve to obtain the flame retardant. Step S5: Weigh 100 parts by weight of copper conductor, 80 parts by weight of modified base material, 15 parts by weight of flame retardant, and 20 parts by weight of intermediate material. The materials used are: aluminum alloy wire AA8030 and 50 parts polyethylene LD608; Step S6: The copper conductor is laid out and heated to 100°C using a preheater. Half of the modified base material is extruded over the copper conductor using a first extruder to form an inner sheath. The remaining half of the modified base material is mixed with a flame retardant in a side feeder and extruded over the inner sheath using a second extruder to form an insulating flame-retardant layer. This is added to a vulcanizing tube and cross-linked under nitrogen at 200°C and 1.2 MPa. After natural cooling to 25°C, the aluminum alloy wire AA8030 is braided over the insulating flame-retardant layer with a coverage rate of ≥80% using a high-speed braiding machine to form a metal shielding layer. The polyethylene LD608 is extruded over the metal shielding layer using a third extruder and then cooled and shaped in a water bath to obtain a cross-linked polyethylene insulated flame-retardant power cable.

[0025] Comparative Example 1: This comparative example is a method for preparing a cross-linked polyethylene insulated flame-retardant power cable, including the following steps: Step S1: 55g of low-density polyethylene 2102N3W, 23g of ethylene-vinyl acetate resin 53007, 18g of ethylene propylene diene monomer (EPDM) rubber, and 12g of polyolefin elastomer (POE) are mixed. C0570 is added to a two-roll mill at a roller temperature of 110℃ and a roller gap of 2mm. The mixture is kneaded for 13 minutes, then 4g of dicumyl peroxide and 2g of triallyl isocyanurate are added. The roller gap is adjusted to 1mm, and the mixture is kneaded for another 30 minutes. The mixture is then transferred to a flat vulcanizing press and heated at 180℃ and 5MPa for 4 minutes. The pressure is increased to 13MPa, and the mixture is held at 180℃ for 15 minutes. The mixture is then transferred to a cold press and cooled to 25℃ at 13MPa to obtain the base material. The antioxidant is a mixture of antioxidant 1010 and antioxidant didodecane thiodipropionate at a mass ratio of 2:1. Step S2: 90 parts by weight of copper conductor, 75 parts by weight of base material, and 13 parts by weight of flame retardant APYRAL are weighed. 15. 18 parts aluminum alloy wire AA8030 and 48 parts polyethylene LD608; Step S3: The copper conductor is laid out and heated to 90°C by a preheater. Co-extrusion crosslinking is used. Half of the total base material is extruded over the copper conductor through the first extruder to form an inner sheath. The remaining half of the base material is mixed with flame retardant APYRAL 15 in a side feeder and extruded over the inner sheath through the second extruder to form an insulating flame retardant layer. It is added to the vulcanizing tube and crosslinked in a nitrogen environment of 190°C and 1MPa. It is then naturally cooled to 25°C. The aluminum alloy wire AA8030 is braided over the insulating flame retardant layer with a coverage of ≥80% through a high-speed braiding machine to form a metal shielding layer. The polyethylene LD608 is extruded over the metal shielding layer through the third extruder and cooled and shaped in a water tank to obtain a crosslinked polyethylene insulated flame retardant power cable.

[0026] Comparative Example 2: This comparative example is a method for preparing a cross-linked polyethylene insulated flame-retardant power cable, including the following steps: Step S1: Add 13 mL of eugenol, 120 mL of acetonitrile, and 11 g of anhydrous potassium carbonate to a three-necked flask equipped with a stirrer and a thermometer, purge with nitrogen for protection, mix and stir for 30 min, and set aside; Add 7.5 g of hexachlorocyclotriphosphazene and 80 mL of acetonitrile to a beaker, mix and stir for 30 min, add to the above three-necked flask, and incubate at 85 °C. The mixture was stirred and reacted for 48 hours. After the reaction was completed, it was filtered to remove the filter residue. The filtrate was evaporated using a rotary evaporator and transferred to a round-bottom flask. 100 mL of anhydrous ethanol was added, and the mixture was allowed to stand for 12 hours. The mixture was then filtered, and the filter cake was placed in a vacuum drying oven at 60°C and dried for 9 hours to obtain the functional filler. Step S2: 55 g of low-density polyethylene 2102N3W, 23 g of ethylene-vinyl acetate resin 53007, 18 g of ethylene propylene diene monomer (EPDM) rubber, and 12 g of polyolefin elastomer (POE) were mixed and stirred. C0570 was added to a two-roll open mill at a roll temperature of 110°C and a roll gap of 2 mm. The mixture was kneaded for 13 minutes. Then, 115 g of aluminum hydroxide, 11 g of functional filler, 1.5 g of antioxidant, 2 g of zinc stearate, and 4 g of dibutyl phthalate were added. The mixture was kneaded for another 8 minutes. Then, 4 g of dicumyl peroxide and 2 g of triallyl isocyanurate were added. The roll gap was adjusted to 1 mm, and the mixture was kneaded for another 30 minutes. The mixture was then transferred to a flat vulcanizing mill and kneaded at 18... Heating at 0℃ and 5MPa for 4 minutes, then increasing the pressure to 13MPa, and holding the reaction at 180℃ for 15 minutes, the mixture is transferred to a cold press and cooled to 25℃ at 13MPa to obtain the modified base material; the antioxidant is a mixture of antioxidant 1010 and antioxidant didodecane thiodipropionate in a mass ratio of 2:1; Step S3: Weigh out 90 parts by weight of copper conductor, 75 parts by weight of modified base material, and 13 parts by weight of flame retardant APYRAL. 15. 18 parts of aluminum alloy wire AA8030 and 48 parts of polyethylene LD608; Step S4: The copper conductor is laid out and heated to 90°C by a preheater. Co-extrusion crosslinking is used. Half of the total amount of modified base material is extruded over the copper conductor through the first extruder to form an inner sheath. The remaining half of the total amount of modified base material is mixed with flame retardant in a side feeder and extruded over the inner sheath through a second extruder to form an insulating flame retardant layer. It is added to a vulcanizing tube and crosslinked in a nitrogen environment of 190°C and 1MPa. It is then naturally cooled to 25°C. The aluminum alloy wire AA8030 is braided over the insulating flame retardant layer with a coverage of ≥80% through a high-speed braiding machine to form a metal shielding layer. The polyethylene LD608 is extruded over the metal shielding layer through a third extruder and cooled and shaped in a water tank to obtain a crosslinked polyethylene insulated flame retardant power cable.

[0027] Comparative Example 3: This comparative example is a method for preparing a cross-linked polyethylene insulated flame-retardant power cable, including the following steps: Step S1: 55g of low-density polyethylene 2102N3W, 23g of ethylene-vinyl acetate resin 53007, 18g of ethylene propylene diene monomer (EPDM) rubber, and 12g of polyolefin elastomer POE C0570 are added to a two-roll mill. The roll temperature is 110℃, the roll gap is 2mm, and the mixture is mixed for 13min. Then, 4g of dicumyl peroxide and 2g of triallyl isocyanurate are added, the roll gap is adjusted to 1mm, and the mixture is continued to be mixed for 30min. The mixture is then transferred to a flat vulcanizing machine and heated at 180℃ and 5MPa for 4min. The pressure is increased to 13MPa, and the mixture is held at 180℃ for 15min. The mixture is then transferred to a cold press and cooled to 25℃ at 13MPa to obtain the base material. The antioxidant is composed of antioxidant 1010 and antioxidant didodecane thiodipropionate in a mass ratio of 2:1. 1. Mixed together; Step S2: Add 7g of attapulgite and 100mL of deionized water to a three-necked flask equipped with a stirrer and thermometer, and sonicate for 35min to obtain a suspension; Add 3.5g of zinc acetate and 100mL of deionized water to a beaker, and mix and stir for 13min to obtain solution A; Add 4.5g of sodium hydroxide and 100mL of deionized water to a beaker, and mix and stir for 13min to obtain solution B; Add 5.5g of crystalline tin tetrachloride and 100mL of deionized water to a beaker, and mix and stir for 13min to obtain solution C; Add solution A, Solution C was added dropwise to the suspension at a rate of 1.5 mL / min, and the mixture was stirred for 16 h. Solution B was then added, and stirring continued for 30 min. The mixture was transferred to a reaction vessel and hydrothermally reacted at 160 °C for 14 h. After naturally cooling to 25 °C, the mixture was allowed to stand for 12 h, filtered, and the filter cake was washed three times with distilled water and anhydrous ethanol, respectively. The cake was then vacuum dried at 60 °C for 24 h, ball-milled for 1.5 h at a speed of 350 r / min and a ball-to-material ratio of 10:1, and sieved through a 250-mesh sieve to obtain the intermediate product. Step S3: 17 g of boric acid and 50 mL of deionized water were added to the mixture equipped with... In a three-necked flask equipped with a stirrer and thermometer, the mixture was magnetically stirred at 200 rpm for 30 min in an oil bath at 95 °C. 5 g of zinc oxide and 12.5 g of attapulgite were added, and the reaction was continued for 7 h. After the reaction was complete, the mixture was filtered, and the filter cake was washed three times with distilled water and vacuum dried at 60 °C for 12 h. It was then ball-milled for 1.5 h at a ball-to-material ratio of 10:1 and sieved through a 250-mesh sieve to obtain the substrate. The substrate and 10 g of intermediate product were added to a planetary ball mill at a ball-to-material ratio of 8:1 and a speed of 350 rpm for 1 h.After 5 hours, the flame retardant is obtained by sieving through a 200-mesh sieve. Step S4: Weigh out 90 parts by weight of copper conductor, 75 parts by weight of base material, 13 parts by weight of flame retardant, 18 parts by weight of aluminum alloy wire AA8030, and 48 parts by weight of polyethylene LD608. Step S5: Wire the copper conductor and heat it to 90°C using a preheater. Co-extrude crosslinking is used to extrude half of the total amount of base material through the first extruder to wrap around the copper conductor, forming an inner protective layer. The remaining half of the total amount of base material and flame retardant are fed sideways. The mixture is prepared in a machine and then extruded through a second extruder to form an insulating and flame-retardant layer outside the inner sheath. This layer is then added to a vulcanizing tube and cross-linked under nitrogen at 190℃ and 1MPa. After natural cooling to 25℃, aluminum alloy wire AA8030 is braided onto the insulating and flame-retardant layer with a coverage rate of ≥80% using a high-speed braiding machine, forming a metal shielding layer. Polyethylene LD608 is then extruded through a third extruder to form the metal shielding layer. Finally, the mixture is cooled and shaped in a water bath to obtain a cross-linked polyethylene insulated flame-retardant power cable.

[0028] The flame-retardant insulation layers of the cross-linked polyethylene insulated flame-retardant power cables prepared in Examples 1-3 and Comparative Examples 1-3 were tested for oxygen index according to standard GB / T 2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test", with sample shape VI. Tensile strength was tested according to standard GB / T 2951.11-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 11: General Test Methods for Thickness and Dimensional Measurements and Mechanical Properties Tests", with test results shown in Figures 2-3. Comparing Examples 1-3 with Comparative Examples 1-3: the amounts of composite flame retardant, functional filler, and aluminum hydroxide increased from Examples 1 to 3, while the amounts of each component in Example 1 were lower. The active point density of the flame retardant that catalyzes char formation and the functional filler that provides gas-phase flame retardancy per unit volume was relatively low, resulting in better strength and integrity of the flame-retardant barrier. Example 1 showed relatively weak flame retardancy and low performance; Example 2 had moderate component dosages, achieving an optimal concentration of flame-retardant active components that effectively covered and catalyzed the polymer matrix, resulting in a good synergistic effect between gas-phase and condensed-phase flame retardancy and superior performance; Example 3 had higher component dosages, increasing the material basis for catalytic char formation and the formation of the heat-insulating glass phase, enabling faster and earlier formation of a thicker protective char layer and achieving optimal performance; Comparing Example 2 with Comparative Example 1 shows that Comparative Example 1 relied solely on the single physical flame-retardant mechanism of the flame retardant APYRAL, while Example 2 employed a "gas-phase-condensed-phase" approach. The synergistic flame-retardant system exhibits significantly higher flame-retardant performance than Comparative Example 1. Comparative Example 1 uses a common base material, resulting in weak interfacial bonding between the flame retardant APYRAL and the matrix, creating stress defect points and lower tensile strength. Comparing Example 2 with Comparative Example 2 reveals that: Comparative Example 2 uses a modified base material and the flame retardant APYRAL, with functional fillers providing supplementary gas-phase flame retardancy; Example 2 introduces a chemically reactive flame retardant, with zinc tin oxide acting as a catalyst, significantly accelerating and guiding the polymer's conversion to a stable char layer, resulting in higher char yield and better char quality. Zinc borate decomposes to form… The resulting glassy body can flow and seal char layer cracks, exhibiting superior flame retardant performance compared to Comparative Example 2. Comparing Example 2 and Comparative Example 3 reveals that: Example 2 and Comparative Example 3 used the same flame retardant, resulting in similar flame retardancy, but Example 2 exhibits significantly higher mechanical properties. Comparative Example 3 directly mixed a highly efficient flame retardant into the unmodified polymer, leading to incompatibility between the inorganic filler and the organic polymer interface, resulting in stress concentration and low mechanical strength. In Example 2, the long-chain organic portion of the functional filler derived from eugenol exhibits good compatibility with the polymer matrix, enhancing the material's mechanical properties.

[0029] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0030] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.

Claims

1. A cross-linked polyethylene insulated flame-retardant power cable, characterized in that, From the inside out, the cable consists of a cable core, an insulating and flame-retardant layer, a metal shielding layer, and an outer sheath. The cable core comprises a conductor and an inner sheath covering the conductor. The conductor diameter is 3.5-3.6 mm, and the inner sheath thickness is 1-1.2 mm. The conductor is a copper conductor. The inner sheath is made from a modified base material. The insulating and flame-retardant layer is made from a modified base material and a flame retardant, and its thickness is 1-1.2 mm. The metal shielding layer is an aluminum alloy wire mesh structure woven from AA8030 aluminum alloy wires with a single filament diameter of 0.3-0.4 mm and a thickness of 0.6-0.8 mm. The outer sheath is made from polyethylene LD608 and has a thickness of 1.6-1.8 mm.

2. The cross-linked polyethylene insulated flame-retardant power cable according to claim 1, characterized in that, The modified base material is prepared by the following steps: Step a1: Eugenol, the first part of acetonitrile, and anhydrous potassium carbonate are added to a three-necked flask and stirred; hexachlorocyclotriphosphazene and the second part of acetonitrile are mixed and stirred, added to the above three-necked flask, stirred to react, filtered, and the filter residue is removed. The filtrate is evaporated using a rotary evaporator, anhydrous ethanol is added, allowed to stand, filtered under vacuum, and the filter cake is dried to obtain the functional filler; Step a2: Low-density polyethylene, ethylene-vinyl acetate resin, EPDM rubber, and polyolefin elastomer are added to a two-roll mill and mixed. Aluminum hydroxide, functional filler, antioxidant, lubricant, and plasticizer are added, and mixing continues. Peroxide crosslinking agent and co-crosslinking agent are added, and mixing is carried out. The mixture is transferred to a flat vulcanizing machine, heated and pressure-held, and then transferred to a cold press to cool to obtain the modified base material.

3. The cross-linked polyethylene insulated flame-retardant power cable according to claim 2, characterized in that, In step a1, the ratio of eugenol, total acetonitrile, anhydrous potassium carbonate, hexachlorocyclotriphosphazene, and anhydrous ethanol is 10-15 mL: 200 mL: 9-12 g: 7-8 g: 100 mL; the first part of acetonitrile accounts for 3 / 5 of the total acetonitrile; and the second part of acetonitrile accounts for 2 / 5 of the total acetonitrile.

4. The cross-linked polyethylene insulated flame-retardant power cable according to claim 2, characterized in that, The ratio of the amounts of low-density polyethylene, ethylene-vinyl acetate resin, ethylene propylene diene monomer (EPDM) rubber, polyolefin elastomer, aluminum hydroxide, functional filler, antioxidant, lubricant, plasticizer, peroxide crosslinking agent, and co-crosslinking agent in step a2 is 50-60g: 20-25g: 15-20g: 10-13g: 100-130g: 10-12g: 1-2g: 1-3g: 3-5g: 2-5g: 1-3g.

5. A cross-linked polyethylene insulated flame-retardant power cable according to claim 2, characterized in that, The low-density polyethylene in step a2 is of type 2102N3W; the ethylene-vinyl acetate resin is of type 53007; the polyolefin elastomer is of type POE C0570; the antioxidant is a mixture of antioxidant 1010 and antioxidant didodecane thiodipropionate in a mass ratio of 2:1; the lubricant is zinc stearate; the plasticizer is dibutyl phthalate; the peroxide crosslinking agent is dicumyl peroxide; and the co-crosslinking agent is triallyl isocyanurate.

6. The cross-linked polyethylene insulated flame-retardant power cable according to claim 1, characterized in that, The flame retardant is prepared by the following steps: Step b1: Attapulgite and a first part of deionized water are ultrasonically dispersed to obtain a suspension; zinc acetate and a second part of deionized water are mixed and stirred to obtain solution A; sodium hydroxide and a third part of deionized water are mixed and stirred to obtain solution B; crystalline tin tetrachloride and a fourth part of deionized water are mixed and stirred to obtain solution C; solutions A and C are added dropwise to the suspension and stirred, then solution B is added and stirred continuously. The mixture undergoes a hydrothermal reaction, is cooled, allowed to stand, filtered, and the filter cake is washed with distilled water and anhydrous ethanol, dried, ball-milled, and sieved to obtain an intermediate product. Step b2: Stir boric acid and deionized water magnetically in an oil bath, add zinc oxide and attapulgite, continue stirring and reacting, filter, wash the filter cake with distilled water, dry, ball mill, and sieve to obtain the substrate; add the substrate and intermediate product to a planetary ball mill for ball milling, sieve, and obtain the flame retardant.

7. A cross-linked polyethylene insulated flame-retardant power cable according to claim 6, characterized in that, In step b1, the ratio of attapulgite, total deionized water, zinc acetate, sodium hydroxide, and crystalline tin tetrachloride is 5-8g:400mL:3-4g:4-5g:5-6g; the first part of deionized water accounts for 1 / 4 of the total deionized water; the second part of deionized water accounts for 1 / 4 of the total deionized water; the third part of deionized water accounts for 1 / 4 of the total deionized water; and the fourth part of deionized water accounts for 1 / 4 of the total deionized water.

8. A cross-linked polyethylene insulated flame-retardant power cable according to claim 6, characterized in that, The ratio of boric acid, deionized water, zinc oxide, attapulgite, and intermediate product used in step b2 is 15-18g: 50mL: 4.5-5.5g: 12-13g: 10g.

9. A method for preparing a cross-linked polyethylene insulated flame-retardant power cable as described in any one of claims 1-8, characterized in that, The process includes the following steps: Step 1: Weigh out 80-100 parts of conductor, 70-80 parts of modified base material, 10-15 parts of flame retardant, 15-20 parts of aluminum alloy wire AA8030, and 45-50 parts of polyethylene LD608 according to weight. Step 2: Lay out the conductor, heat it, and use a co-extrusion cross-linking process. Extrude half of the total amount of modified base material through the first extruder to wrap around the conductor, forming an inner sheath. Mix the remaining half of the base material with the flame retardant in a side feeder, and extrude it through the second extruder to wrap around the inner sheath, forming an insulating and flame-retardant layer. Add it to the vulcanizing tube for cross-linking, cool it, and use a high-speed braiding machine to braid the aluminum alloy wire AA8030 around the insulating and flame-retardant layer to form a metal shielding layer. Extrude the polyethylene LD608 through the third extruder to wrap around the metal shielding layer, and then cool and shape it in a water tank to obtain a cross-linked polyethylene insulated flame-retardant power cable.

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