A synchronous cross-linking flame-retardant cable composite material and its preparation method

Abstract

The present invention provides a synchronous cross-linking flame-retardant cable composite material and a preparation method thereof, which belongs to the technical field of cable materials. In this application, transition metal zirconium phosphate suppresses local discharge through its high dielectric constant and polarization performance, and generates a carbonized layer at high temperature, thereby improving flame retardancy; modified fibers combine the high orientation of liquid crystal polymers with the excellent mechanical and flame retardancy of polyetheretherketone, and form block copolymers through dynamic grafting to enhance the toughness, fatigue life and thermal stability of the material; silane-metal complex precursors enhance the moisture resistance, flame retardancy and thermal insulation properties of the material through the water-sealing effect of the silicon-oxygen network and the "micro-ceramic" layer generated at high temperature; each component shows significant synergistic effects in terms of flame retardancy, electrical properties and mechanical properties, forming multiple flame retardant barriers, stabilizing the electrical properties of the material, and significantly enhancing the overall mechanical properties and interface stability of the composite material.

Description

Technical Field

[0001] The invention belongs to the technical field of cable materials and relates to a synchronous cross-linking flame-retardant cable composite material and a preparation method thereof. Background Art

[0002] Safety and durability are paramount in the application of cable materials. In the use of high-voltage or special flame-retardant cables, faced with complex operating conditions such as high voltage and strong electric fields, high temperature overloads, and humid environments, material degradation, fire risks, and potential electrical failures are core issues that need to be addressed urgently. In practical applications, partial discharge, mechanical stress, and moisture penetration—three major factors—often lead to a rapid decline in cable material performance, increasing safety risks.

[0003] Partial discharge occurs because tiny internal defects may exist in the cable insulation layer under the action of high-voltage electric fields. Once a local high-field strength area is formed, local discharge is easily triggered. The instantaneous high energy generated by local discharge will not only accelerate the local carbonization and decomposition of the material, but also cause the insulation layer to form conductive channels, significantly increasing the risk of breakdown and fire. During the laying, bending or long-term vibration of the cable, mechanical stress concentration areas such as tension and shear often appear. Repeated alternating loads may cause the formation of microcracks, which further expand under high pressure or high temperature conditions, leading to stress fatigue and reduced dielectric strength of the insulation layer, thereby increasing the possibility of electrical failure. In addition, in outdoor or high-humidity environments, moisture may penetrate into the insulation layer through micro-defects in the sheath or end seals, and the migration of moisture in the insulation layer will intensify the hydrolysis of the material, increase ionic conductivity, and form "water trees" or "electrical trees" after coupling with high electric fields. In severe cases, local breakdown and fire may occur.

[0004] Partial discharge, mechanical stress and moisture penetration are three major causes that are coupled and interrelated with each other, forming a vicious cycle and posing severe challenges to the safety and reliability of cables. Summary of the Invention

[0005] In response to the above problems, the purpose of the present invention is to provide a synchronous cross-linked flame-retardant cable composite material and a preparation method thereof. This application solves the problem of performance degradation of cable materials under high electric fields, mechanical stress and humid environments by introducing transition metal zirconium phosphate, modified fibers and silane-metal complex precursors. Transition metal zirconium phosphate inhibits local discharge through its high dielectric constant and polarization properties, and generates a carbonized layer at high temperature, significantly improving the flame retardant properties; the modified fiber utilizes the high orientation of liquid crystal polymers and the excellent mechanical and flame retardant properties of polyetheretherketone to form a block copolymer through dynamic grafting, thereby enhancing the toughness, fatigue life and thermal stability of the material; the silane-metal complex precursor improves the moisture resistance, flame retardancy and thermal insulation properties of the material through the water-sealing effect of the silicon-oxygen network and the "micro-ceramic" layer generated at high temperature. In addition, the components show significant synergistic effects in flame retardancy, electrical properties and mechanical properties, forming multiple flame retardant barriers, stabilizing the electrical properties of the material, and significantly enhancing the overall mechanical properties and interface stability of the composite material.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a synchronously cross-linked flame-retardant cable composite material, the method comprising:

[0008] S1: dispersing zirconium phosphate and rare earth oxide in a phosphoric acid solution to obtain a mixed dispersion, adjusting the pH to obtain a reaction solution A, reacting, filtering, washing, and calcining to obtain a doped and modified transition metal phosphate powder; immersing the doped and modified transition metal phosphate powder in an ethanol aqueous solution of a silane coupling agent to obtain a surface-modified doped transition metal phosphate powder;

[0009] S2: treating polyetheretherketone with plasma to obtain modified polyetheretherketone; preparing a propylene glycol dispersion of a liquid crystal polymer, adding ethylenediamine dropwise to obtain a modified liquid, stirring the mixture for reaction, cooling the mixture, filtering, washing, and drying the mixture to obtain a modified liquid crystal polymer; placing the modified liquid crystal polymer and the modified polyetheretherketone into a twin-screw extruder for melt mixing to obtain a blend, extruding the blend to form a yarn, and cutting the blend into segments to obtain a modified fiber;

[0010] S3: Under a nitrogen atmosphere, aluminum isopropoxide is added to γ-aminopropyltriethoxysilane to obtain a reaction solution B, and the mixture is stirred to obtain a silane-metal complex precursor;

[0011] S4: Cross-linked polyethylene and the surface-modified doped transition metal phosphate powder are mixed in a twin-screw extruder to obtain a first mixture, modified fiber is added and mixed evenly, and then a silane-metal complex precursor is injected to obtain a second mixture, dicumyl peroxide and antioxidant 1010 are added, mixed evenly, extruded, and cured to obtain a synchronous cross-linked flame-retardant cable composite material.

[0012] As a preferred technical solution of the present invention, in step S1, the rare earth oxide is either lanthanum oxide or cerium oxide;

[0013] In some optional embodiments, the molar ratio of the zirconium phosphate to the rare earth oxide is 50:1-2, for example, it can be 50:1, 50:1.1, 50:1.2, 50:1.3, 50:1.4, 50:1.5, 50:1.6, 50:1.7, 50:1.8, 50:1.9 or 50:2, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0014] In some optional embodiments, the concentration of the phosphoric acid solution is 1-2M, for example, it can be 1M, 1.1M, 1.2M, 1.3M, 1.4M, 1.5M, 1.6M, 1.7M, 1.8M, 1.9M or 2M, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] In some optional embodiments, the molar ratio of phosphoric acid to zirconium phosphate in the mixed dispersion is 1.5-2:1, for example, it can be 1.5:1, 1.55:1, 1.6:1, 1.65:1, 1.7:1, 1.75:1, 1.8:1, 1.85:1, 1.9:1, 1.95:1 or 2:1, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0016] In some optional embodiments, the pH of the mixed dispersion is adjusted to 1.5-2.5, for example, it can be 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4 or 2.5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] In some optional embodiments, the reaction temperature of the reaction liquid A is 80-100°C, for example, it can be 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0018] In some optional embodiments, the reaction time of the reaction liquid A is 4-8h, for example, it can be 4h, 4.4h, 4.8h, 5.2h, 5.6h, 6h, 6.4h, 6.8h, 7.2h, 7.6h or 8h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] In some optional embodiments, the calcination temperature is 600-800°C, for example, it can be 600°C, 620°C, 640°C, 660°C, 680°C, 700°C, 720°C, 740°C, 760°C, 780°C or 800°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] In some optional embodiments, the calcination time is 2-4h, for example, it can be 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.2h, 3.4h, 3.6h, 3.8h or 4h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] In some optional embodiments, the mass fraction of the ethanol aqueous solution of the silane coupling agent KH560 is 1-2 wt.%, for example, it can be 1 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, 1.5 wt.%, 1.6 wt.%, 1.7 wt.%, 1.8 wt.%, 1.9 wt.% or 2 wt.%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0022] In some optional embodiments, the volume ratio of ethanol to water in the ethanol aqueous solution is 7:3-9:1, for example, it can be 7:3, 7.2:2.8, 7.4:2.6, 7.6:2.4, 7.8:2.2, 8:2, 8.2:1.8, 8.4:1.6, 8.6:1.4, 8.8:1.2 or 9:1, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0023] In some optional embodiments, the mass ratio of the doped modified transition metal phosphate powder to the silane coupling agent KH-560 is 100:1-2, for example, it can be 100:1, 100:1.1, 100:1.2, 100:1.3, 100:1.4, 100:1.5, 100:1.6, 100:1.7, 100:1.8, 100:1.9 or 100:2, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] As a preferred technical solution of the present invention, in step S2, for example, it can be 100W, 110W, 120W, 130W, 140W, 150W, 160W, 170W, 180W, 190W or 200W, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0025] In some optional embodiments, the air inlet flow rate during the polyetheretherketone plasma treatment is 20-30 sccm, for example, it can be 20 sccm, 21 sccm, 22 sccm, 23 sccm, 24 sccm, 25 sccm, 26 sccm, 27 sccm, 28 sccm, 29 sccm or 30 sccm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] In some optional embodiments, the mass volume ratio of liquid crystal polymer to propylene glycol in the propylene glycol dispersion of the liquid crystal polymer is 1-2 g / 10 mL, for example, it can be 1 g / 10 mL, 1.1 g / 10 mL, 1.2 g / 10 mL, 1.3 g / 10 mL, 1.4 g / 10 mL, 1.5 g / 10 mL, 1.6 g / 10 mL, 1.7 g / 10 mL, 1.8 g / 10 mL, 1.9 g / 10 mL or 2 g / 10 mL, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0027] In some optional embodiments, the mass volume ratio of the liquid crystal polymer to ethylenediamine is 1-2 g / mL, for example, it can be 1 g / mL, 1.1 g / mL, 1.2 g / mL, 1.3 g / mL, 1.4 g / mL, 1.5 g / mL, 1.6 g / mL, 1.7 g / mL, 1.8 g / mL, 1.9 g / mL or 2 g / mL, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0028] In some optional embodiments, the temperature of the modified liquid stirring reaction is 120-130°C, for example, it can be 120°C, 121°C, 122°C, 123°C, 124°C, 125°C, 126°C, 127°C, 128°C, 129°C or 130°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0029] In some optional embodiments, the stirring reaction time of the modified liquid is 4-5h, for example, it can be 4h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h or 5h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] In some optional embodiments, the mass ratio of the modified liquid crystal polymer to the modified polyetheretherketone is 70:30-50:50, for example, it can be 70:30, 68:32, 66:34, 64:36, 62:38, 60:40, 58:42, 56:44, 54:46, 52:48 or 50:50, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0031] In some optional embodiments, the temperature for melt mixing of the modified liquid crystal polymer and the modified polyetheretherketone is 320-330°C, for example, it can be 320°C, 321°C, 322°C, 323°C, 324°C, 325°C, 326°C, 327°C, 328°C, 329°C or 330°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0032] In some optional embodiments, the screw speed of the twin-screw extruder is 100-200 rpm, for example, it can be 100 rpm, 110 rpm, 120 rpm, 130 rpm, 140 rpm, 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm or 200 rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] In some optional embodiments, the pore size of the blend drawing is 0.15-0.25 mm, for example, it can be 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm or 0.25 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] In some optional embodiments, the length of the modified fiber is 3-6 mm, for example, 3 mm, 3.3 mm, 3.6 mm, 3.9 mm, 4.2 mm, 4.5 mm, 4.8 mm, 5.1 mm, 5.4 mm, 5.7 mm or 6 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable. As a preferred technical solution of the present invention, in step S3, the mass ratio of the γ-aminopropyltriethoxysilane to aluminum isopropoxide is 80-90:20-10, for example, 80:20, 81:19, 82:18, 83:17, 84:16, 85:15, 86:14, 87:13, 88:12, 89:11 or 90:10, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0035] In some optional embodiments, the stirring temperature of the reaction liquid B is 50-70°C, for example, it can be 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C or 70°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0036] In some optional embodiments, the stirring time of the reaction liquid B is 1-2h, for example, it can be 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] As a preferred technical solution of the present invention, in step S4, the temperature of the feeding section of the twin-screw extruder is 150-160°C, for example, it can be 150°C, 151°C, 152°C, 153°C, 154°C, 155°C, 156°C, 157°C, 158°C, 159°C or 160°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0038] In some optional embodiments, the operating temperature of the discharge section of the twin-screw extruder is 200-220°C, for example, it can be 200°C, 202°C, 204°C, 206°C, 208°C, 210°C, 212°C, 214°C, 216°C, 218°C or 220°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0039] The mass ratio of the cross-linked polyethylene, the surface-modified doped transition metal phosphate powder, the modified fiber, the silane-metal complex precursor, the dicumyl peroxide, and the antioxidant 1010 is 100:(5-10):(2-6):(3-8):(0.5-2):(0.2-0.5).

[0040] In some optional embodiments, the curing temperature is 80-100°C, for example, it can be 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] In some optional embodiments, the curing time is 8-12 hours, for example, it can be 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours or 12 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] In some optional embodiments, the humidity during curing is 80%-90%, for example, it can be 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89% or 90%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] In a second aspect, the present invention provides a synchronous cross-linking flame retardant cable composite material.

[0044] In a high electric field environment, partial discharge is a major problem faced by cable materials during service. Partial discharge can cause local distortion of the electric field, significantly reduce the dielectric strength of the material, and even cause insulation failure, thereby shortening the service life of the material. Therefore, the transition metal zirconium phosphate is introduced in this application. Zirconium phosphate has a high dielectric constant and polarization performance, and its ionic structure can undergo electric dipole polarization or relaxation in a strong electric field. This characteristic enables it to absorb local electric field spike energy, thereby effectively suppressing electric field distortion and reducing the damage to the material caused by partial discharge. At the same time, by doping with rare earth elements, the dielectric properties of zirconium phosphate can be further regulated to enhance its polarization ability and relaxation effect under strong electric fields.

[0045] Furthermore, zirconium phosphate decomposes at high temperatures to produce phosphate products and metal oxides. The phosphate products catalyze the carbonization of the material surface, forming a protective layer, while the metal oxides further enhance the density of the carbonized layer, reducing the heat release rate during combustion. This carbonized layer effectively blocks the diffusion of oxygen, heat, and combustible gases, significantly improving the material's flame retardancy.

[0046] However, zirconium phosphate, as an inorganic material, easily aggregates within a cross-linked polyethylene matrix, resulting in localized uneven performance. To address this issue, this application utilizes a silane coupling agent to modify the surface of the zirconium phosphate. The silane coupling agent forms an organic surface layer on the particle surface, reducing polar interactions between particles and thus reducing agglomeration. Furthermore, the organic groups of the silane coupling agent can physically entangle or chemically bond with the polyethylene matrix, improving the dispersion of the particles within the matrix and enhancing interfacial bonding strength.

[0047] Cable materials will be subjected to mechanical stress and thermal environment during long-term service, and are prone to microcracks or fatigue damage, resulting in degradation of mechanical properties. Therefore, modified fibers are introduced in this application to modify them. Liquid crystal polymer (LCP) molecular chains are highly oriented and rigid, and can form fibrous or lamellar oriented structures, effectively dispersing external mechanical stresses. Their high melting point and low thermal expansion coefficient give them good dimensional stability and thermal properties at high temperatures. The aromatic skeleton of polyetheretherketone (PEEK) gives it excellent mechanical and thermal stability, and also has good flame retardant properties. Both liquid crystal polymers and polyetheretherketones have excellent mechanical properties and heat resistance, but liquid crystal polymers and polyetheretherketones have different chemical properties. Direct blending may lead to phase separation or poor interfacial adhesion, which in turn affects mechanical properties.

[0048] Therefore, the polyetheretherketone is plasma treated to introduce reactive groups, and the liquid crystal polymer is modified so that the two can undergo a dynamic grafting reaction during high-temperature melt blending to form block or grafted copolymers. The block copolymer formed by dynamic grafting builds a uniform interaction network inside the fiber, significantly improving the mechanical stability of the fiber. In addition, the grafted fibers are easier to disperse in the matrix resin and can form a stronger interfacial bonding force with the matrix, further improving the toughness and fatigue life of the composite material. At the same time, the aromatic carbonized residues of LCP and PEEK are superimposed in a high-temperature environment to form a dense carbonized layer, thereby further enhancing the flame retardant properties and thermal stability of the material.

[0049] Cables may face erosion in humid environments during long-term operation, and moisture infiltration will cause material performance degradation, such as increased dielectric loss and decreased mechanical properties. Therefore, a silane-metal complex precursor is introduced in this application to deal with this problem. The silane-metal complex precursor effectively copes with humid environments through the dual functions of "water sealing" and "flame retardant ceramicization": silane can form a silicon-oxygen network through hydrolysis, capturing moisture inside the material, forming a dense barrier to prevent further penetration of external moisture; and metal alkoxide aluminum isopropoxide is complexed with silane hydrolysis products to form a silicon-oxygen-metal network structure with a high cross-linking density, making the material more stable in a hot and humid environment; at the same time, at high temperatures, the complex decomposes to generate metal oxides and silicates, which aggregate to form a "micro-ceramic" layer, which not only has a flame retardant effect, but also significantly enhances the thermal insulation and thermal stability of the material.

[0050] In the subsequent cross-linking and curing stage, cross-linked polyethylene generates free radicals through the thermal decomposition of diisopropylbenzene peroxide, and the molecular chains undergo a cross-linking reaction to form a three-dimensional network structure, thereby providing the material with mechanical and thermal stability. During this process, the silane-metal complex precursor undergoes a hydrolysis and condensation reaction under wet and hot conditions to form a silicon-oxygen network, which is then physically entangled or chemically bonded with the matrix to form a composite network. The surface-modified transition metal zirconium phosphate is bonded to the matrix through the interfacial reaction of the silane coupling agent, further improving the interfacial bonding strength and dispersibility. In addition, the modified liquid crystal polymer and the modified polyetheretherketone undergo a dynamic grafting reaction under high-temperature blending conditions to form a block copolymer, which is evenly distributed in the matrix to enhance the mechanical properties and interfacial stability of the composite material. These synergistic effects significantly improve the overall performance of the composite material.

[0051] There is also a synergistic effect in this application. In terms of synergistic flame retardancy, the "micro-ceramic" layer generated by the silane-metal complex precursor and the carbonized layer generated by the transition metal phosphate work together to form a multiple flame retardant barrier. The aromatic carbonized residue of the modified fiber is superimposed on the above barrier to further enhance the flame retardant effect. In terms of synergistic enhancement of electrical properties, the surface-modified zirconium phosphate suppresses local discharge and reduces the degradation of dielectric properties caused by electric field distortion, while the water-sealing function of the silane-metal complex precursor further stabilizes the electrical properties of the material. In terms of mechanical stability and interface stability, the highly oriented stress dispersion system provided by the modified fiber and the uniform distribution of the surface-modified doped transition metal phosphate powder work together to improve the overall mechanical properties of the composite material.

[0052] As the instruction manual Figure 1 As shown, the obtained synchronous cross-linking flame-retardant cable composite material is coated on the outside of the composite battery core to obtain a flame-retardant cable.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] To address insulation failure in cable materials caused by partial discharge, this application introduces transition metal zirconium phosphate, which suppresses electric field distortion through its high dielectric constant and polarization properties. Rare earth elements are added to enhance its polarization capability, while its high-temperature decomposition products form a dense carbonized layer to improve flame retardancy. To improve its dispersion in the matrix, a silane coupling agent is used to modify the zirconium phosphate surface, reducing agglomeration and enhancing interfacial bonding, significantly improving the material's uniformity and stability.

[0055] To improve the mechanical properties of cable materials under long-term mechanical stress and thermal environments, this application introduces modified fibers for modification. Liquid crystal polymers disperse mechanical stress through their high degree of orientation and rigidity, and possess excellent dimensional stability and thermal properties. The aromatic backbone of polyetheretherketone provides exceptional mechanical strength, thermal stability, and flame retardancy. Modification of the two allows dynamic grafting during high-temperature melt blending to form a block copolymer, enhancing fiber dispersibility and interfacial bonding, thereby improving the toughness, fatigue life, and flame retardancy of the composite material.

[0056] In order to cope with the erosion of cable material performance by humid environments, this application introduces a silane-metal complex precursor to improve material performance through the dual functions of "water sealing" and "flame retardant ceramicization". Silane hydrolyzes to form a silicon-oxygen network, which captures internal moisture and prevents external moisture from penetrating, while aluminum isopropylate complexes with silane to form a silicon-oxygen-metal network structure with a high cross-linking density, enhancing the material's wet-heat stability. At the same time, the complex decomposes at high temperatures to form metal oxides and silicates, forming a "micro-ceramic" layer, which significantly improves the material's flame retardancy, thermal insulation properties, and thermal stability.

[0057] This application fully embodies the synergistic effect: in terms of flame retardancy, the "micro-ceramic" layer of the silane-metal complex precursor and the carbonized layer of the transition metal phosphate work together, and the aromatic carbonized residue of the modified fiber is superimposed to form a multiple flame retardant barrier; in terms of electrical performance improvement, the surface-modified zirconium phosphate inhibits local discharge, and the water-sealing function of the silane-metal complex precursor stabilizes the dielectric properties; in terms of mechanical properties, the highly oriented stress dispersion system of the modified fiber and the uniformly distributed modified zirconium phosphate jointly enhance the overall mechanical properties and interface stability of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Schematic diagram of a cable prepared by the synchronous cross-linking flame-retardant cable composite material prepared by the preparation method described in Example 1 of the present application.

[0059] Explanation of the accompanying figures: 1. Synchronous cross-linking flame-retardant cable composite material; 2. Internal battery core. DETAILED DESCRIPTION

[0060] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments and the accompanying drawings. The embodiments described herein are specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be understood as limiting the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications made to the embodiments described herein.

[0061] The chemical reagents used in the examples and comparative examples of the present invention are all commercially available products without further purification or treatment.

[0062] The polyetheretherketone trade name is Victrex 450G;

[0063] The liquid crystal polymer product name is Vectra A950;

[0064] Example 1

[0065] This embodiment provides a synchronous cross-linking flame-retardant cable composite material and a preparation method thereof. The preparation method of the synchronous cross-linking flame-retardant cable composite material specifically comprises the following steps:

[0066] S1: Dispersing zirconium phosphate and rare earth oxide lanthanum oxide in a 1.5M phosphoric acid solution at a molar ratio of 50:1.8 to obtain a mixed dispersion, wherein the molar ratio of phosphoric acid to zirconium phosphate is 1.8:1, adjusting the pH to 2 to obtain a reaction solution A, reacting at 90°C for 6 hours, filtering, washing, and calcining at 700°C for 3 hours to obtain a doped modified transition metal phosphate powder; immersing the mixture in an ethanol aqueous solution containing a silane coupling agent KH-560 with a mass fraction of 1.8wt.%, wherein the mass ratio of the doped modified transition metal phosphate powder to the silane coupling agent is 100:1.7, and the volume ratio of ethanol to water in the ethanol aqueous solution is 7:3, to obtain a surface-modified doped transition metal phosphate powder;

[0067] S2: treating polyetheretherketone with plasma to obtain modified polyetheretherketone, wherein the power of the polyetheretherketone plasma treatment is 150W and the air inlet flow rate is 25sccm; preparing a propylene glycol dispersion of a liquid crystal polymer with a mass volume ratio of 1.5g / 10mL, adding ethylenediamine dropwise to obtain a modified solution, wherein the mass volume ratio of the liquid crystal polymer to ethylenediamine is 1.8g / mL, stirring and reacting at 120°C for 4.6h, cooling, filtering, washing, and drying to obtain a modified liquid crystal polymer; putting the modified liquid crystal polymer and the modified polyetheretherketone into a twin-screw extruder for melt mixing to obtain a blend, wherein the mass ratio of the liquid crystal polymer to the polyetheretherketone is 70:30, the temperature is 325°C, the screw speed is 100rpm, extruding and drawing, and cutting into segments to obtain modified fibers, wherein the pore diameter of the drawing is 0.25mm and the length of the modified fiber is 0.3mm;

[0068] S3: Under a nitrogen atmosphere, aluminum isopropoxide was added to γ-aminopropyltriethoxysilane to obtain a reaction solution B, wherein the mass ratio of γ-aminopropyltriethoxysilane to aluminum isopropoxide was 85:15, and the mixture was stirred at 60° C. for 1.5 h to obtain a silane-metal complex precursor;

[0069] S4: Cross-linked polyethylene and surface-modified doped transition metal phosphate powder are mixed in a twin-screw extruder to obtain a first mixture, modified fiber is added and mixed evenly, and then a silane-metal complex precursor is injected to obtain a second mixture, diisopropyl peroxide and antioxidant 1010 are added, mixed evenly, extruded, and cured to obtain a synchronous cross-linked flame-retardant cable composite material, wherein the temperature of the feeding section of the twin-screw extruder is 150°C, the working temperature of the discharging section is 210°C, the curing temperature is 95°C, the time is 10 hours, the humidity is 85%, and the mass ratio of cross-linked polyethylene, surface-modified doped transition metal phosphate powder, modified fiber, silane-metal complex precursor, diisopropyl peroxide, and antioxidant 1010 is 100:8:5:6:1:0.3.

[0070] Example 2

[0071] This embodiment provides a synchronous cross-linking flame-retardant cable composite material and a preparation method thereof. The preparation method of the synchronous cross-linking flame-retardant cable composite material specifically comprises the following steps:

[0072] S1: Dispersing zirconium phosphate and rare earth oxide cerium oxide in a 1M phosphoric acid solution at a molar ratio of 50:1 to obtain a mixed dispersion, wherein the molar ratio of phosphoric acid to zirconium phosphate is 1.7:1, adjusting the pH to 2.2 to obtain a reaction solution A, reacting at 95°C for 4 hours, filtering, washing, and calcining at 760°C for 3.5 hours to obtain a doped and modified transition metal phosphate powder; immersing the mixture in an ethanol aqueous solution containing a silane coupling agent KH-560 with a mass fraction of 1 wt.%, wherein the mass ratio of the doped and modified transition metal phosphate powder to the silane coupling agent is 100:1, and the volume ratio of ethanol to water in the ethanol aqueous solution is 8:2, to obtain a surface-modified doped transition metal phosphate powder;

[0073] S2: treating polyetheretherketone with plasma to obtain modified polyetheretherketone, wherein the power of the polyetheretherketone plasma treatment is 180W and the air inlet flow rate is 20sccm; preparing a propylene glycol dispersion of a liquid crystal polymer with a mass volume ratio of 1.7g / 10mL, adding ethylenediamine dropwise to obtain a modified solution, wherein the mass volume ratio of the liquid crystal polymer to ethylenediamine is 1g / mL, stirring and reacting at 126°C for 4.8h, cooling, filtering, washing, and drying to obtain a modified liquid crystal polymer; putting the modified liquid crystal polymer and the modified polyetheretherketone into a twin-screw extruder for melt mixing to obtain a blend, wherein the mass ratio of the liquid crystal polymer to the polyetheretherketone is 60:40, the temperature is 328°C, the screw speed is 150rpm, extruding and drawing, and cutting into segments to obtain modified fibers, wherein the pore diameter of the drawing is 0.15mm and the length of the modified fiber is 0.6mm;

[0074] S3: Under a nitrogen atmosphere, aluminum isopropoxide was added to γ-aminopropyltriethoxysilane to obtain a reaction solution B, wherein the mass ratio of γ-aminopropyltriethoxysilane to aluminum isopropoxide was 87:13, and the mixture was stirred at 65° C. for 1.8 h to obtain a silane-metal complex precursor;

[0075] S4: Cross-linked polyethylene and surface-modified doped transition metal phosphate powder are mixed in a twin-screw extruder to obtain a first mixture, modified fiber is added and mixed evenly, and then a silane-metal complex precursor is injected to obtain a second mixture, diisopropyl peroxide and antioxidant 1010 are added, mixed evenly, extruded, and cured to obtain a synchronous cross-linked flame-retardant cable composite material, wherein the temperature of the feeding section of the twin-screw extruder is 159°C, the operating temperature of the discharging section is 215°C, the curing temperature is 80°C, the time is 8h, the humidity is 87%, and the mass ratio of cross-linked polyethylene, surface-modified doped transition metal phosphate powder, modified fiber, silane-metal complex precursor, diisopropyl peroxide, and antioxidant 1010 is 100:5:4:7:1.5:0.4.

[0076] Example 3

[0077] This embodiment provides a synchronous cross-linking flame-retardant cable composite material and a preparation method thereof. The preparation method of the synchronous cross-linking flame-retardant cable composite material specifically comprises the following steps:

[0078] S1: Dispersing zirconium phosphate and rare earth oxide cerium oxide in a 1.8M phosphoric acid solution at a molar ratio of 50:1.5 to obtain a mixed dispersion, wherein the molar ratio of phosphoric acid to zirconium phosphate is 1.5:1, adjusting the pH to 1.5 to obtain a reaction solution A, reacting at 80°C for 7 hours, filtering, washing, and calcining at 600°C for 2 hours to obtain a doped modified transition metal phosphate powder; immersing the powder in an ethanol aqueous solution containing a silane coupling agent KH-560 with a mass fraction of 2 wt.%, wherein the mass ratio of the doped modified transition metal phosphate powder to the silane coupling agent is 100:2, and the volume ratio of ethanol to water in the ethanol aqueous solution is 7:3, to obtain a surface-modified doped transition metal phosphate powder;

[0079] S2: treating polyetheretherketone with plasma to obtain modified polyetheretherketone, wherein the power of the polyetheretherketone plasma treatment is 100W and the air inlet flow rate is 28sccm; preparing a propylene glycol dispersion of a liquid crystal polymer with a mass volume ratio of 1g / 10mL, adding ethylenediamine dropwise to obtain a modified solution, wherein the mass volume ratio of the liquid crystal polymer to ethylenediamine is 2g / mL, stirring and reacting at 128°C for 4h, cooling, filtering, washing, and drying to obtain a modified liquid crystal polymer; putting the modified liquid crystal polymer and the modified polyetheretherketone into a twin-screw extruder for melt mixing to obtain a blend, wherein the mass ratio of the liquid crystal polymer to the polyetheretherketone is 65:35, the temperature is 320°C, the screw speed is 180rpm, extruding and drawing, and cutting into segments to obtain modified fibers, wherein the pore diameter of the drawing is 0.2mm and the length of the modified fiber is 0.4mm;

[0080] S3: Under a nitrogen atmosphere, aluminum isopropoxide was added to γ-aminopropyltriethoxysilane to obtain a reaction solution B, wherein the mass ratio of γ-aminopropyltriethoxysilane to aluminum isopropoxide was 80:20, and the mixture was stirred at 50° C. for 1 h to obtain a silane-metal complex precursor;

[0081] S4: Cross-linked polyethylene and surface-modified doped transition metal phosphate powder are mixed in a twin-screw extruder to obtain a first mixture, modified fiber is added and mixed evenly, and then a silane-metal complex precursor is injected to obtain a second mixture, diisopropyl peroxide and antioxidant 1010 are added, mixed evenly, extruded, and cured to obtain a synchronous cross-linked flame-retardant cable composite material, wherein the temperature of the feeding section of the twin-screw extruder is 157°C, the operating temperature of the discharging section is 200°C, the curing temperature is 90°C, the time is 12h, the humidity is 80%, and the mass ratio of cross-linked polyethylene, surface-modified doped transition metal phosphate powder, modified fiber, silane-metal complex precursor, diisopropyl peroxide, and antioxidant 1010 is 100:7:2:3:0.5:0.2.

[0082] Example 4

[0083] This embodiment provides a synchronous cross-linking flame-retardant cable composite material and a preparation method thereof. The preparation method of the synchronous cross-linking flame-retardant cable composite material specifically comprises the following steps:

[0084] S1: Dispersing zirconium phosphate and rare earth oxide lanthanum oxide in a 2M phosphoric acid solution at a molar ratio of 50:2 to obtain a mixed dispersion, wherein the molar ratio of phosphoric acid to zirconium phosphate is 2:1, adjusting the pH to 2.5 to obtain a reaction solution A, reacting at 100°C for 8 hours, filtering, washing, and calcining at 800°C for 4 hours to obtain a doped and modified transition metal phosphate powder; immersing the mixture in an ethanol aqueous solution containing a silane coupling agent KH-560 with a mass fraction of 1.5wt.%, wherein the mass ratio of the doped and modified transition metal phosphate powder to the silane coupling agent is 100:1.4, and the volume ratio of ethanol to water in the ethanol aqueous solution is 9:1, to obtain a surface-modified doped transition metal phosphate powder;

[0085] S2: treating polyetheretherketone with plasma to obtain modified polyetheretherketone, wherein the power of the polyetheretherketone plasma treatment is 200W and the air inlet flow rate is 30sccm; preparing a propylene glycol dispersion of a liquid crystal polymer with a mass volume ratio of 2g / 10mL, adding ethylenediamine dropwise to obtain a modified solution, wherein the mass volume ratio of the liquid crystal polymer to ethylenediamine is 1.5g / mL, stirring and reacting at 130°C for 5h, cooling, filtering, washing, and drying to obtain a modified liquid crystal polymer; putting the modified liquid crystal polymer and the modified polyetheretherketone into a twin-screw extruder for melt mixing to obtain a blend, wherein the mass ratio of the liquid crystal polymer to the polyetheretherketone is 50:50, the temperature is 330°C, the screw speed is 200rpm, extruding and drawing, and cutting into segments to obtain modified fibers, wherein the pore diameter of the drawing is 0.22mm and the length of the modified fiber is 0.5mm;

[0086] S3: Under a nitrogen atmosphere, aluminum isopropoxide was added to γ-aminopropyltriethoxysilane to obtain a reaction solution B, wherein the mass ratio of γ-aminopropyltriethoxysilane to aluminum isopropoxide was 90:10, and the mixture was stirred at 70° C. for 2 h to obtain a silane-metal complex precursor;

[0087] S4: Cross-linked polyethylene and surface-modified doped transition metal phosphate powder are mixed in a twin-screw extruder to obtain a first mixture, modified fiber is added and mixed evenly, and then a silane-metal complex precursor is injected to obtain a second mixture, diisopropyl peroxide and antioxidant 1010 are added, mixed evenly, extruded, and cured to obtain a synchronous cross-linked flame-retardant cable composite material, wherein the temperature of the feeding section of the twin-screw extruder is 160°C, the working temperature of the discharging section is 220°C, the curing temperature is 100°C, the time is 11 hours, the humidity is 90%, and the mass ratio of cross-linked polyethylene, surface-modified doped transition metal phosphate powder, modified fiber, silane-metal complex precursor, diisopropyl peroxide, and antioxidant 1010 is 100:10:6:8:2:0.5.

[0088] Comparative Example 1

[0089] This comparative example provides a synchronous cross-linking flame-retardant cable composite material, which differs from Example 1 in that, in S4, no surface-modified doped transition metal phosphate powder is added, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0090] Comparative Example 2

[0091] This comparative example provides a synchronous cross-linking flame-retardant cable composite material, which differs from Example 1 in that, in S4, only surface-modified doped transition metal phosphate powder is added, and modified fiber and silane-metal complex precursor are not added. The other operating steps and process parameters are exactly the same as those in Example 1.

[0092] Comparative Example 3

[0093] This comparative example provides a synchronous cross-linking flame-retardant cable composite material, which differs from Example 1 in that, in S4, no modified fiber is added, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0094] Comparative Example 4

[0095] This comparative example provides a synchronous cross-linking flame-retardant cable composite material, which differs from Example 1 in that, in S4, only modified fibers are added, and surface-modified doped transition metal phosphate powder and silane-metal complex precursor are not added. The other operating steps and process parameters are exactly the same as those in Example 1.

[0096] Comparative Example 5

[0097] This comparative example provides a synchronous cross-linking flame-retardant cable composite material, which differs from Example 1 in that, in S4, no silane-metal complex precursor is added, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0098] Comparative Example 6

[0099] This comparative example provides a synchronous cross-linking flame-retardant cable composite material, which differs from Example 1 in that, in S4, only a silane-metal complex precursor is added, and no surface-modified doped transition metal phosphate powder and modified fiber are added. The other operating steps and process parameters are exactly the same as those in Example 1.

[0100] The performance test of the synchronous cross-linked flame retardant cable composite materials of Examples 1 to 4 and Comparative Examples 1 to 6 was carried out, and the specific process is as follows:

[0101] Test the oxygen index of the sample according to GB / T2406.2-2009;

[0102] The tensile properties of the samples were tested according to GB / T1040.2-2022;

[0103] The volume resistivity of the sample is tested according to GB / T31838.2-2019;

[0104] Partial discharge resistance test: Test the sample's partial discharge breakdown time at a voltage of 2.0 kV and a frequency of 400 Hz;

[0105] The test results are shown in Table 1.

[0106] Moisture resistance test: Soak the sample in water for 30 days, then conduct a performance test and calculate its retention rate.

[0107] Retention rate = (performance after soaking in water / original performance) × 100%;

[0108] The test results are shown in Table 2.

[0109] Table 1: Performance test results of synchronous cross-linked flame retardant cable composite materials of Examples 1 to 4 and Comparative Examples 1 to 6

[0110]

[0111] Table 2: Test results of moisture resistance retention of synchronous cross-linked flame retardant cable composite materials of Examples 1 to 4 and Comparative Examples 1 to 6

[0112]

[0113] As shown in Tables 1 and 2, the test results of Example 1 and Comparative Example 1 demonstrate that the surface-modified doped transition metal phosphate powder is the primary flame retardant additive in the material system. Its surface modification improves interfacial bonding with the substrate and provides an effective flame retardant barrier through polarization effects and the formation of a carbonized layer at high temperatures. Omitting this powder reduces the material's flame retardancy, significantly decreasing the oxygen index. Furthermore, the modified zirconium phosphate primarily enhances flame retardancy and electrical properties, with a minimal direct contribution to mechanical properties, leaving the tensile strength largely unchanged. The polarization and uniform dispersion of zirconium phosphate significantly enhance the material's insulation and suppress partial discharge. Omitting this powder leads to unstable dielectric properties, reduced volume resistivity, and decreased partial discharge resistance. Furthermore, the surface-modified zirconium phosphate enhances the material's moisture tolerance through interfacial bonding with the substrate. Without this powder, the material's moisture resistance weakens, resulting in reduced performance retention.

[0114] From the test results of Example 1 and Comparative Example 2, it can be seen that the introduction of surface-modified zirconium phosphate provides the main flame retardant barrier for the material, but due to the lack of the synergistic ceramic effect of the silane-metal complex precursor, the flame retardant performance of the material is reduced; at the same time, the lack of the reinforcing effect of the modified fiber, especially the contribution of the block copolymer network formed by its dynamic grafting, leads to a significant decrease in the tensile strength of the material; the high polarization property of zirconium phosphate still gives the material a higher volume resistivity and partial discharge resistance, but due to the lack of the water-sealing effect of the silane network, the moisture resistance of the material is reduced, and moisture intrusion further affects the performance retention rate.

[0115] From the test results of Example 1 and Comparative Example 3, it can be seen that the modified fiber has a small direct contribution to the flame retardant properties, so the oxygen index does not change much; the mechanical reinforcement provided by the modified fiber is missing, resulting in a significant decrease in the tensile strength of the material; at the same time, the synergistic effect of the silane-metal complex precursor and zirconium phosphate can still give the material a higher volume resistivity and partial discharge resistance; the lack of the interface reinforcement effect of the modified fiber has a certain negative impact on the tensile strength retention rate of the material.

[0116] From the test results of Example 1 and Comparative Example 4, it can be seen that due to the lack of modified zirconium phosphate powder and silane-metal complex precursor, the material loses its key flame retardant barrier and the oxygen index is significantly reduced; the modified fiber has a more significant enhancing effect on the mechanical properties of the material, and the tensile strength does not change much; at the same time, the lack of the polarization properties of zirconium phosphate and the water-sealing effect of the silane network leads to a decrease in volume resistivity and partial discharge resistance; due to the lack of the water-sealing function of the silane-metal complex precursor, moisture intrusion increases, which further reduces the performance retention rate of the material.

[0117] From the test results of Example 1 and Comparative Example 5, it can be seen that the ceramicizing effect of the silane-metal complex precursor is lacking, the flame retardant barrier of the material is insufficient, and the oxygen index is reduced; the reinforcing effect of the modified fiber still exists, and the effect on the tensile strength is small; due to the lack of the water-sealing effect of the silane network, the volume resistivity and partial discharge resistance are reduced, and at the same time, moisture intrusion is significantly increased, resulting in a decrease in performance retention rate.

[0118] From the test results of Example 1 and Comparative Example 6, it can be seen that the direct flame retardant effect of the modified zirconium phosphate is lacking, and the ceramic effect of the silane network alone cannot provide an efficient flame retardant barrier, and the flame retardant performance is significantly reduced; the mechanical properties of the material are significantly reduced due to the lack of the reinforcing effect of the modified fiber; although the water-sealing function of the silane complex has a certain contribution to the electrical properties, the overall electrical properties are still reduced; the water-sealing function of the silane complex effectively slows down the impact of moisture on the material properties to a certain extent, so that the moisture-proof performance retention rate is relatively high.

[0119] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a synchronous cross-linking flame-retardant cable composite material, characterized in that: The preparation method comprises: S1: dispersing zirconium phosphate and rare earth oxide in a phosphoric acid solution to obtain a mixed dispersion, adjusting the pH to obtain a reaction solution A, reacting, filtering, washing, and calcining to obtain a doped and modified transition metal phosphate powder; immersing the doped and modified transition metal phosphate powder in an ethanol aqueous solution of a silane coupling agent to obtain a surface-modified doped transition metal phosphate powder; S2: treating polyetheretherketone (PEEK) by plasma treatment to obtain modified PEEK; preparing a propylene glycol dispersion of a liquid crystal polymer, adding ethylenediamine dropwise to obtain a modified solution, stirring the solution for reaction, cooling, filtering, washing, and drying to obtain a modified liquid crystal polymer; placing the modified liquid crystal polymer and the modified PEEK into a twin-screw extruder for melt mixing to obtain a blend, extruding the blend to form a yarn, and cutting the blend into segments to obtain modified fibers; wherein the liquid crystal polymer is VECTRA® E130i; S3: Under a nitrogen atmosphere, aluminum isopropoxide is added to γ-aminopropyltriethoxysilane to obtain a reaction solution B, and the mixture is stirred to obtain a silane-metal complex precursor; S4: Cross-linked polyethylene and the surface-modified doped transition metal phosphate powder are mixed in a twin-screw extruder to obtain a first mixture, modified fiber is added and mixed evenly, and then a silane-metal complex precursor is injected to obtain a second mixture, dicumyl peroxide and antioxidant 1010 are added, mixed evenly, extruded, and cured to obtain a synchronous cross-linked flame-retardant cable composite material.

2. The method for preparing a synchronous cross-linking flame-retardant cable composite material according to claim 1, characterized in that: In S1: The rare earth oxide is either lanthanum oxide or cerium oxide; The molar ratio of the zirconium phosphate to the rare earth oxide is 50:(1-2).

3. The method for preparing a synchronous cross-linking flame-retardant cable composite material according to claim 1, characterized in that: In S1: The molar ratio of phosphoric acid to zirconium phosphate in the mixed dispersion is (1.5-2):1; The mass ratio of the doped modified transition metal phosphate powder to the silane coupling agent is 100:(1-2).

4. The method for preparing a synchronous cross-linking flame-retardant cable composite material according to claim 1, characterized in that: In S2: The mass volume ratio of the liquid crystal polymer to propylene glycol in the propylene glycol dispersion of the liquid crystal polymer is (1-2) g / 10 mL; The mass volume ratio of the liquid crystal polymer to ethylenediamine is (1-2) g / mL.

5. The method for preparing a synchronous cross-linking flame-retardant cable composite material according to claim 1, characterized in that: In S2: the mass ratio of the modified liquid crystal polymer to the modified polyetheretherketone is (70:30)-(50:50).

6. The method for preparing a synchronous cross-linking flame-retardant cable composite material according to claim 1, characterized in that: In S2: The temperature for melt mixing of the modified liquid crystal polymer and the modified polyetheretherketone is 320-330°C; The screw speed of the twin-screw extruder is 100-200 rpm.

7. The method for preparing a synchronous cross-linking flame-retardant cable composite material according to claim 1, characterized in that: In S3: the mass ratio of the γ-aminopropyltriethoxysilane to aluminum isopropoxide is (80-90):(20-10).

8. The method for preparing a synchronous cross-linking flame-retardant cable composite material according to claim 1, characterized in that: In S4: The temperature of the feeding section of the twin-screw extruder is 150-160°C; The operating temperature of the discharge section of the twin-screw extruder is 200-220°C.

9. The method for preparing a synchronous cross-linking flame-retardant cable composite material according to claim 1, characterized in that: In S4: the mass ratio of the cross-linked polyethylene, the surface-modified doped transition metal phosphate powder, the modified fiber, the silane-metal complex precursor, the diisopropylbenzene peroxide, and the antioxidant 1010 is 100: (5-10): (2-6): (3-8): (0.5-2): (0.2-0.5).

10. A synchronous cross-linking flame-retardant cable composite material, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 9.

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