A cable material and a method for producing the same

Abstract

The application provides a cable material and a preparation method thereof, and belongs to the cable material field.The cable material is composed of the following chemical components: linear low-density polyethylene: 80-90 parts, dicumyl peroxide: 0.6-1.0 parts, triallyl isocyanurate: 1.6-2.4 parts, hydroxylated boron nitride nanosheet: 10-15 parts, N-(vinylbenzyl) carbazole-3-(triethoxysilyl) propyl ether: 0.8-1.6 parts, antioxidant: 0.4-1.1 parts, and lubricant: 0.5-1 part.The components of the cable material are reasonably designed, so that the insulation, heat conductivity, stability and recyclability of the cable material are simultaneously improved.

Description

Technical Field

[0001] This application relates to the field of cable material production technology, and in particular to a cable material and its preparation method. Background Technology

[0002] In the fields of power transmission and communication, cables serve as the core carrier, and their performance directly determines the safety, stability, and efficiency of system operation. With rapid technological advancements, higher demands are being placed on the insulation, thermal conductivity, stability, and recyclability of cable materials. However, simultaneously improving these four properties presents numerous contradictions, representing a significant challenge currently facing the materials science field.

[0003] Insulation is the cornerstone of cable materials, preventing current leakage and ensuring transmission safety. While traditional cross-linked polyethylene (XLPE) and similar materials can meet basic insulation requirements, adding highly thermally conductive inorganic particles to improve thermal conductivity can easily lead to uneven particle dispersion, forming conductive paths, resulting in decreased insulation resistance, increased dielectric loss, and compromised insulation performance. Thermal conductivity directly affects cable lifespan and safety; if heat cannot be dissipated in time during operation, it will accelerate material aging and even cause accidents. Adding thermally conductive fillers such as nanoparticles can improve thermal conductivity, but excessive addition can disrupt the continuity of the insulation material, introduce defects, reduce insulation performance, and may also make the material brittle and hard, affecting processing and installation. Stability determines the long-term reliability of cables. Traditional materials such as PE-XL cables have poor thermal stability and are prone to aging under long-term high-field-strength, thermally cycling environments, leading to a decline in mechanical, insulation properties, and breakdown field strength. Furthermore, adding additives to improve recyclability may introduce impurities or active groups, further accelerating aging. Recyclability is an environmental trend. Traditional cross-linked materials such as XLPE have complex processes, high energy consumption, and are difficult to recycle after disposal, and the treatment methods pollute the environment. Although polypropylene (PP)-based recyclable materials have good insulation and temperature resistance, they have problems such as high rigidity, poor low-temperature toughness, poor aging resistance and thermal conductivity. During modification, the addition of toughening agents may also affect the insulation and recyclability.

[0004] Chinese patent CN113563666A discloses a high-temperature-resistant polypropylene cable insulation material and its preparation method, which prepares the cable material by melt blending polypropylene, antioxidants, dispersants, and silicon nitride. While this method improves some properties to a certain extent, its effect on improving insulation is limited. Furthermore, it does not fully consider the synergistic improvement of insulation, thermal conductivity, stability, and recyclability, making it difficult to meet the high-performance requirements of modern cables in practical applications. Therefore, developing a cable material and its preparation method that can simultaneously improve insulation, thermal conductivity, stability, and recyclability is urgently needed, and is of great significance for promoting the development of the power and communications industries. Summary of the Invention

[0005] This application provides a cable material and a method for preparing the same, in order to solve the following technical problem: how to simultaneously improve the insulation, thermal conductivity, stability and recyclability of cable materials.

[0006] In a first aspect, this application provides a cable material, which, by weight, is composed of the following chemical components: linear low-density polyethylene: 80-90 parts, dicumyl peroxide: 0.6-1.0 parts, triallyl isocyanurate: 1.6-2.4 parts, hydroxylated boron nitride nanosheets: 10-15 parts, N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether: 0.8-1.6 parts, antioxidant: 0.4-1.1 parts, and lubricant: 0.5-1 parts.

[0007] Optionally, the linear low-density polyethylene has a melt index of 0.5–5 g / 10 min and a density of 0.915–0.935 g / cm³. 3 .

[0008] Optionally, the antioxidant is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl) phosphite, wherein the mass ratio of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] to tris(2,4-di-tert-butylphenyl) phosphite is (0.2-0.5):(0.3-0.6).

[0009] Optionally, the lubricant includes one or more of zinc stearate, ethylene bis-stearamide, and silicone lubricants.

[0010] Optionally, the method for preparing the hydroxylated boron nitride nanosheets includes: Hexagonal boron nitride was refluxed in concentrated nitric acid for 12–24 h to carry out preliminary oxidation and obtain pretreated boron nitride. Hydrogen peroxide was added to the pretreated boron nitride dispersion, and then the reaction was carried out at 60–120 °C and 0.1–2.0 MPa for 6–24 h. The reaction solution was then separated into solid and liquid phases to obtain the hydroxylated boron nitride nanosheets.

[0011] Optionally, the thickness of the hexagonal boron nitride sheet is 10–100 nm, and the sheet diameter is 1–10 μm.

[0012] Optionally, the preparation method of the N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether includes: Under an inert atmosphere, 3-hydroxycarbazole, a first basic catalyst and a first organic solvent were mixed, and 3-chloropropyltriethoxysilane was slowly added. The mixture was reacted at 80-100°C for 8-15 hours, and 3-(3-triethoxysilylpropoxy)carbazole was obtained after post-treatment. Under an inert atmosphere, the 3-(3-triethoxysilylpropoxy)carbazole, the second basic catalyst, and the second organic solvent were mixed, and p-vinylbenzyl chloride was slowly added. The mixture was reacted at 70–85 °C for 6–12 h. The reaction solution was concentrated and purified by column chromatography to obtain the N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether.

[0013] Optionally, the first alkaline catalyst is anhydrous potassium carbonate or anhydrous sodium carbonate; The second alkaline catalyst is anhydrous potassium carbonate or anhydrous sodium carbonate; The first organic solvent is N,N-dimethylformamide, dimethyl sulfoxide, or acetonitrile; The molar ratio of the 3-hydroxycarbazole, the first alkaline catalyst, and the 3-chloropropyltriethoxysilane is 1:(1.2-1.8):(1.0-1.2). The second organic solvent is acetonitrile, tetrahydrofuran, or acetone; The molar ratio of the 3-(3-triethoxysilylpropoxy)carbazole, the second basic catalyst, and the p-vinylbenzyl chloride is 1:(1.2-1.5):(0.8-1.2).

[0014] Secondly, this application provides a method for preparing the cable material according to any one of the first aspects, the method comprising: Linear low-density polyethylene, dicumyl peroxide, triallyl isocyanurate, hydroxylated boron nitride nanosheets, N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether, antioxidant and lubricant are mixed at high speed and at 40-60°C for 5-15 min to obtain a premix. The premixed material is added to a twin-screw extruder, and after melt blending, reactive extrusion, and granulation, the cable material is obtained.

[0015] Optionally, the processing temperature of the twin-screw extruder is controlled in five zones: zone 1 is 140-150℃, zone 2 is 150-160℃, zone 3 is 160-170℃, zone 4 is 170-180℃, the die head is 175-185℃, and the screw speed is 150-350 r / min.

[0016] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a cable material that, through the rational design of its various components, simultaneously improves insulation, thermal conductivity, stability, and recyclability. Linear low-density polyethylene (80-90 parts) serves as the material matrix, possessing excellent electrical insulation properties and providing basic insulation protection for cable materials. N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether (0.8-1.6 parts) is the key to insulation enhancement. The carbazole core in its molecule has an electron-rich conjugated structure that can be uniformly distributed within the material, effectively capturing and binding charges, introducing deep-level traps, and inhibiting the accumulation of space charges within the material. The synergistic effect of the two significantly improves the overall insulation performance of the cable material. Hydroxylated boron nitride nanosheets (10-15 parts) are the core source of thermal conductivity. They have high thermal conductivity and can build a "heat highway" inside the material, providing a channel for heat conduction. At the same time, N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether can form covalent bonds with the hydroxyl groups on the surface of the hydroxylated boron nitride nanosheets through the siloxane end in the molecular structure, firmly integrating the hydroxylated boron nitride nanosheets into the material system, reducing the interfacial thermal resistance between the thermally conductive filler and the matrix, allowing for more efficient heat conduction, and further optimizing the thermal conductivity. 0.4 to 1.1 parts of antioxidant can specifically inhibit the thermo-oxidative aging of materials during processing and long-term use, capture free radicals generated during aging, decompose hydrogen peroxide, and delay the degradation of material performance. In addition, the carbazole structure in N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether also has a certain antioxidant capacity, which can help antioxidants protect the linear low-density polyethylene molecular chain and the bonds between various components, and jointly enhance the long-term stability of the material. Triallyl isocyanurate (1.6–2.4 parts) is a key component that imparts recyclability to the material. The ester functional groups in its molecule can form reversible dynamic covalent bonds under high-temperature conditions. These dynamic bonds can temporarily break during high-temperature processing, giving the material thermoplastic processing properties. After cooling, they can recombine to form a cross-linked network, allowing the material to be reprocessed and recycled after use. Simultaneously, 0.5–1 part of lubricant reduces frictional resistance during processing, ensuring uniform dispersion of all components and supporting the smooth progress of the material recycling process. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart illustrating a method for preparing a cable material according to an embodiment of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0022] This application provides a cable material, which, by weight, is composed of the following chemical components: linear low-density polyethylene: 80-90 parts, dicumyl peroxide: 0.6-1.0 parts, triallyl isocyanurate: 1.6-2.4 parts, hydroxylated boron nitride nanosheets: 10-15 parts, N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether: 0.8-1.6 parts, antioxidant: 0.4-1.1 parts, and lubricant: 0.5-1 parts.

[0023] In some embodiments, the linear low-density polyethylene has a melt index of 0.5–5 g / 10 min and a density of 0.915–0.935 g / cm³. 3 .

[0024] In some embodiments, the antioxidant is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl) phosphite, wherein the mass ratio of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] to tris(2,4-di-tert-butylphenyl) phosphite is (0.2-0.5):(0.3-0.6).

[0025] In some embodiments, the lubricant includes one or more of zinc stearate, ethylene bis-stearamide, and silicone lubricants.

[0026] On the one hand, in the cable material system of this application, each component forms a precise division of labor around the construction and functional optimization of the "three-dimensional dynamic cross-linked network," achieving a synergistic improvement in insulation, thermal conductivity, stability, and recyclability through molecular-level interactions. The specific roles of each component are as follows: Linear low-density polyethylene (LLDPE, 80-90 parts per liter) serves as the matrix and skeleton of the material, forming the core structural support of the entire cable material. Its primary function is to provide basic electrical insulation, ensuring the cable does not experience leakage or other safety issues during energization; it also imparts necessary mechanical strength, ensuring the cable can withstand certain external forces during laying and use without easily being damaged; furthermore, it possesses good processability, facilitating subsequent melting, molding, and other processing steps. From a reaction perspective, the carbon atoms in its molecular chain are the "anchor points" for all chemical reactions, providing crucial reaction sites for subsequent grafting and cross-linking reactions with other components.

[0027] Dicumyl peroxide (DCP, 0.6–1.0 parts) acts as a free radical initiator, serving as the "power source" for initiating the construction of the entire material's chemical network. Under high-temperature processing or usage conditions, it decomposes to generate highly reactive free radicals. These free radicals can precisely capture hydrogen atoms from the LLDPE molecular chains, transforming the originally stable LLDPE molecular chains into reactive LLDPE macromolecular free radicals. This lays the foundation for subsequent crosslinking and grafting reactions between LLDPE and other components. Without DCP, the construction of the entire chemical network cannot be initiated.

[0028] Triallyl isocyanurate (TAIC, 1.6–2.4 parts) plays a dual role as a co-crosslinking agent and a source of dynamic covalent bonds. On the one hand, multiple double bonds in its molecular structure can react with the free radicals of LLDPE macromolecules initiated by DCP, crosslinking different LLDPE molecular chains together and helping to build a stable three-dimensional polymer network. On the other hand, functional groups such as ester groups in the molecule can form reversible dynamic covalent bonds under high temperature conditions. These bonds can temporarily break at high temperatures and recombine after cooling, giving the material thermoplastic and recyclable properties. This allows the material to be reprocessed and molded after use by heating, improving environmental friendliness and resource utilization.

[0029] Hydroxylated boron nitride nanosheets (BNNS-OH, 10–15 parts) are the core functional filler for achieving high thermal conductivity and high insulation performance in materials. They possess extremely high thermal conductivity, which is crucial for constructing the material's internal "heat highway," rapidly conducting heat generated during cable operation and preventing localized overheating that could negatively impact cable performance and lifespan. Simultaneously, they exhibit excellent electrical insulation properties, preventing the degradation of insulation performance caused by the addition of thermally conductive fillers. Furthermore, the surface-modified hydroxyl groups (-OH) serve as important reaction sites, providing a "handle" for interfacial chemical reactions with other components and achieving strong interfacial bonding.

[0030] N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether (trap bridging agent, 0.8–1.6 parts) is the key innovation hub of the entire material system, possessing triple functions as a molecular bridge, a deep-level trap provider, and an interface bonder. In terms of molecular connection, the vinyl group at one end can react with LLDPE macromolecular free radicals in a DCP-initiated free radical environment, grafting itself onto the polymer network; the triethoxysilyl group at the other end hydrolyzes to generate silanol (-Si-OH), which can undergo a condensation reaction with the hydroxyl groups on the surface of BNNS-OH to form a strong Si-OB covalent bond, thus firmly integrating BNNS-OH into the three-dimensional network. In terms of functional endowment, the carbazole core in the molecule has an electron-rich conjugated structure that can be uniformly distributed within the material (especially at the interface between LLDPE and BNNS-OH), effectively capturing and binding charges, introducing deep-level traps, inhibiting the accumulation of space charge within the material, and directly improving the insulation performance of the material; simultaneously, the carbazole structure also possesses certain antioxidant capabilities, which can help delay material aging.

[0031] The antioxidant (0.4–1.1 parts, a compound system of antioxidants 1010 and 168) primarily functions to inhibit thermo-oxidative aging of materials during processing and long-term use, thus extending the material's service life. Antioxidant 1010, as the primary antioxidant (free radical scavenger), actively captures free radicals remaining from DCP decomposition, as well as alkyl free radicals (R・) and peroxide free radicals (ROO・) generated during material aging, terminating the free radical chain oxidation reaction and preventing the oxidation process from continuing. Antioxidant 168, as an auxiliary antioxidant (hydroperoxide decomposer), specifically decomposes hydroperoxides (ROOH) generated during material oxidation, converting them into stable alcohol compounds, thus cutting off the generation pathway of new free radicals at the source. The combined use of these two antioxidants produces a synergistic antioxidant effect, comprehensively resisting the damage caused by thermo-oxidative processes to the material.

[0032] Lubricant (0.5-1 part) is an auxiliary component that ensures smooth material processing. Its core function is to reduce internal friction (friction between polymer molecular chains) and external friction (friction between molten material and processing equipment) during the melt processing, improve melt fluidity, and ensure that components such as LLDPE, BNNS-OH, and trap bridging agents can be uniformly dispersed during processing, avoiding fluctuations in core properties such as thermal conductivity and insulation caused by component agglomeration. At the same time, it can also reduce wear on processing equipment, reduce processing energy consumption, improve the surface finish of the material after molding, and ensure the quality stability of the final cable product.

[0033] On the other hand, the components work closely together to build and optimize the "three-dimensional dynamic cross-linking network", achieving synergistic improvement in four dimensions: structure, performance, stability, and environmental protection, and building a high-performance cable material system.

[0034] At the basic structural level, LLDPE, DCP, and TAIC form a core collaborative structure. The free radicals generated by the decomposition of DCP provide active sites for LLDPE, while TAIC crosslinks the LLDPE molecular chains into a three-dimensional network through its multiple double bond structure, while also introducing dynamic covalent bonds. Together, the three construct a "stable and recyclable" polymer matrix. This crosslinked network ensures the mechanical strength and structural stability of the material under high-temperature operating conditions, while the dynamic bonds endow the material with recyclable and reprocessable properties, solving the problem of the difficulty in recycling traditional crosslinked polymers.

[0035] In terms of synergistic enhancement of thermal conductivity and insulation properties, the trap bridging agent plays a key pivotal role, connecting BNNS-OH and the LLDPE matrix. Through the covalent bond reaction at both ends of the trap bridging agent, BNNS-OH is firmly integrated into the three-dimensional network of LLDPE. This not only significantly reduces the interfacial thermal resistance between LLDPE and BNNS-OH, allowing the "thermal highway" constructed by BNNS-OH to efficiently conduct heat and improve the material's thermal conductivity, but also avoids the interfacial defects caused by uneven dispersion of traditional fillers. At the same time, the deep-level traps introduced by the trap bridging agent can suppress the accumulation of space charge at the interface, enabling the material to maintain excellent insulation while achieving high thermal conductivity, thus solving the industry problem of balancing thermal conductivity and insulation.

[0036] In terms of long-term stability assurance, the antioxidant system and the trap bridging agent form a "dual protection". Antioxidants 1010 and 168 are combined to block oxidation reactions at two stages: "capturing free radicals" and "decomposing hydrogen peroxides". The carbazole structure in the trap bridging agent helps resist thermo-oxidative corrosion through its own antioxidant capacity. The three work together to protect the LLDPE molecular chain, dynamic cross-linking bonds, and interfacial covalent bonds between LLDPE and BNNS-OH from thermo-oxidative aging damage, ensuring that the thermal conductivity, insulation, and mechanical properties of the material remain stable after long-term high-temperature operation, thus extending the service life of the cable.

[0037] In terms of processing and performance uniformity, lubricants ensure the synergistic effect of all components. By reducing frictional resistance during processing, they ensure that components such as LLDPE, BNNS-OH, and trap bridging agents are uniformly dispersed in the molten state. This prevents the thermal conductivity channels from breaking due to BNNS-OH agglomeration or the trapping function from failing due to uneven distribution of the trap bridging agent, thus ensuring consistent thermal conductivity and insulation properties in all areas of the material and laying the foundation for the stable performance of the material's core properties.

[0038] In summary, this cable material system forms an organic whole that synergistically improves "structure, performance, stability, and environmental protection," ultimately achieving comprehensive optimization of the material's insulation, thermal conductivity, stability, and recyclability.

[0039] In some embodiments, the method for preparing the hydroxylated boron nitride nanosheets includes: Hexagonal boron nitride was refluxed in concentrated nitric acid for 12–24 h to carry out preliminary oxidation and obtain pretreated boron nitride. Hydrogen peroxide was added to the pretreated boron nitride dispersion, and then the reaction was carried out at 60–120 °C and 0.1–2.0 MPa for 6–24 h. The reaction solution was then separated into solid and liquid phases to obtain the hydroxylated boron nitride nanosheets.

[0040] In some embodiments, the thickness of the hexagonal boron nitride sheet is 10–100 nm, and the sheet diameter is 1–10 μm.

[0041] It should be noted that in the initial oxidation stage, hexagonal boron nitride is refluxed in concentrated nitric acid for 12–24 hours. Concentrated nitric acid, as a strong oxidant, can break the weak interactions between boron nitride layers and introduce a small number of oxygen-containing functional groups, laying the foundation for subsequent deep hydroxylation. The 12–24 hour reaction time ensures a moderate degree of oxidation—too short a time results in insufficient oxidation, making subsequent exfoliation difficult; too long a time may damage the layer structure and affect thermal conductivity. Hexagonal boron nitride with a layer thickness of 10–100 nm and a sheet diameter of 1–10 μm is selected as the raw material. This size range ensures both high thermal anisotropy and facilitates effective exfoliation during the oxidation process.

[0042] In the deep hydroxylation stage, hydrogen peroxide was added to the pretreated boron nitride dispersion, and the reaction was carried out at 60–120 °C and 0.1–2.0 MPa pressure for 6–24 h. Hydrogen peroxide, as a mild oxidant, can further introduce hydroxyl (-OH) functional groups; the temperature range of 60–120 °C can activate the reaction activity while avoiding the collapse of the sheet structure due to high temperature; the pressure of 0.1–2.0 MPa helps to increase the concentration of oxidant in the reaction system and accelerate the hydroxylation process. The reaction time of 6–24 h can be controlled according to the target hydroxyl content. Finally, boron nitride nanosheets with hydroxyl-rich surfaces are obtained through solid-liquid separation, providing sufficient reaction sites for subsequent covalent bonding with trap bridging agents.

[0043] In some embodiments, the preparation method of the N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether includes: Under an inert atmosphere, 3-hydroxycarbazole, a first basic catalyst and a first organic solvent were mixed, and 3-chloropropyltriethoxysilane was slowly added. The mixture was reacted at 80-100°C for 8-15 hours, and 3-(3-triethoxysilylpropoxy)carbazole was obtained after post-treatment. Under an inert atmosphere, the 3-(3-triethoxysilylpropoxy)carbazole, the second basic catalyst, and the second organic solvent were mixed, and p-vinylbenzyl chloride was slowly added. The mixture was reacted at 70–85 °C for 6–12 h. The reaction solution was concentrated and purified by column chromatography to obtain the N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether.

[0044] In some embodiments, the first alkaline catalyst is anhydrous potassium carbonate or anhydrous sodium carbonate; The second alkaline catalyst is anhydrous potassium carbonate or anhydrous sodium carbonate; The first organic solvent is N,N-dimethylformamide, dimethyl sulfoxide, or acetonitrile; The molar ratio of the 3-hydroxycarbazole, the first alkaline catalyst, and the 3-chloropropyltriethoxysilane is 1:(1.2-1.8):(1.0-1.2). The second organic solvent is acetonitrile, tetrahydrofuran, or acetone; The molar ratio of the 3-(3-triethoxysilylpropoxy)carbazole, the second basic catalyst, and the p-vinylbenzyl chloride is 1:(1.2-1.5):(0.8-1.2).

[0045] It should be noted that the molecular formula of N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether is C 30 H 37 NO4Si, the structural formula is as follows:

[0046] In the first step of the reaction (introduction of siloxane groups), under an inert atmosphere (such as nitrogen), 3-hydroxycarbazole and 3-chloropropyltriethoxysilane react at 80–100 °C for 8–15 h in an alkaline catalyst and organic solvent. The inert atmosphere prevents oxidation of the starting material; the alkaline catalyst promotes the dissociation of the hydroxyl group in 3-hydroxycarbazole, enhancing its nucleophilicity and driving the substitution reaction with the chloropropyl group; the temperature of 80–100 °C ensures a moderate reaction rate and avoids side reactions; and the reaction time of 8–15 h ensures complete conversion of the starting material. In a molar ratio of 1:(1.2–1.8):(1.0–1.2), excess alkaline catalyst increases the conversion rate of 3-hydroxycarbazole, while an appropriate proportion of 3-chloropropyltriethoxysilane reduces the formation of byproducts, ultimately yielding the siloxane-terminated intermediate 3-(3-triethoxysilylpropoxy)carbazole. The reaction formula for the first step synthesis of 3-(3-triethoxysilylpropoxy)carbazole is: 3-hydroxycarbazole + Cl-(CH2)3-Si(OEt)3 → 3-(3-triethoxysilylpropoxy)carbazole.

[0047] In the second step (introduction of vinyl groups), also under an inert atmosphere, the above intermediate reacts with p-vinylbenzyl chloride in an alkaline catalyst and organic solvent at 70–85 °C for 6–12 h. The reaction temperature of 70–85 °C is lower than that of the first step to avoid thermal decomposition of the vinyl double bond; the reaction time of 6–12 h ensures that the nitrogen atom on the carbazole ring undergoes a complete substitution reaction with the p-vinylbenzyl chloride. In a molar ratio of 1:(1.2–1.5):(0.8–1.2), excess alkaline catalyst promotes the nucleophilic reaction of the nitrogen atom, while the p-vinylbenzyl chloride ratio balances reaction completeness and product purity. Finally, through concentration and column chromatography purification, a target trap bridging agent containing vinyl groups (for grafting polymer networks), a carbazole ring (providing deep-level traps), and siloxane groups (for linking boron nitride) is obtained. Step 2: The reaction formula for synthesizing N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether is: 3-(3-triethoxysilylpropoxy)carbazole + Cl-CH2-C6H4-CH=CH2 → N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether.

[0048] The 1H NMR and HR-MS information of the target product synthesized according to the preparation method provided in this application is as follows: 1HNMR(400MHz, Chloroform-*d*)δ8.10(d, J=7.8Hz, 1H), 8.05(d, J=7.8Hz, 1H), 7.45–7.40( m, 2H), 7.35–7.25 (m, 6H), 7.20–7.10 (m, 2H), 6.70 (dd, J=17.6, 10.9Hz, 1H), 5.72 (d, J=17.6 5.22 (d, J=10.9Hz, 1H), 5.15 (s, 2H), 4.45 (t, J=6.0Hz, 2H), 3.80 (q, J=7.0Hz, 6H), 2.00 (quin, J=6.0Hz, 2H), 1.20 (t, J=7.0Hz, 9H), 0.70 (t, J=8.0Hz, 2H). HR-MS(ESI): Calculated values ​​for C 30 H 38 NO4Si + [M+H] + Experimental value: 516.2568. This indicates that N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether was successfully synthesized according to the method provided in this application.

[0049] Figure 1 This is a schematic flowchart illustrating a method for preparing a cable material according to an embodiment of this application.

[0050] Based on a general inventive concept, such as Figure 1 As shown, this application provides a method for preparing the cable material according to any one of the first aspects, the method comprising: S1. Linear low-density polyethylene, dicumyl peroxide, triallyl isocyanurate, hydroxylated boron nitride nanosheets, N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether, antioxidant and lubricant are mixed at high speed and at 40-60°C for 5-15 min to obtain a premix. S2. The premixed material is added to a twin-screw extruder, and after melt blending, reactive extrusion, and granulation, the cable material is obtained.

[0051] In some embodiments, the processing temperature of the twin-screw extruder is controlled in five zones: zone 1 is 140-150°C, zone 2 is 150-160°C, zone 3 is 160-170°C, zone 4 is 170-180°C, the die head is 175-185°C, and the screw speed is 150-350 r / min.

[0052] Under the gradient temperature field (zone 140-150℃ → zone 2 150-160℃ → zone 3 160-170℃ → zone 4 170-180℃ → die head 175-185℃) and shear action of a twin-screw extruder, the components gradually construct a three-dimensional dynamic cross-linked network through stepwise reactions. The specific process is as follows: Zone 1 (140–150°C) is the melting and initial dispersion stage. Linear low-density polyethylene (LLDPE) begins to melt at this temperature, forming a continuous phase matrix. Dicumyl peroxide (DCP) remains stable as the temperature has not reached the decomposition threshold (approximately 160°C) and is uniformly dispersed in the LLDPE melt. Hydroxylated boron nitride nanosheets (BNNS-OH), trap bridging agents, triallyl isocyanurate (TAIC), antioxidants, and lubricants are dispersed in the molten LLDPE under the shearing action of the screw. The siloxane ends of the trap bridging agents begin to hydrolyze slightly to generate silanols (-Si-OH), preparing for the subsequent reaction with BNNS-OH. This stage is primarily physical mixing; the chemical reaction has not yet begun.

[0053] In zone two (150–160 °C), the free radical initiation and active site generation stage occurs. As the temperature rises, DCP begins to decompose, generating a small amount of free radicals. These free radicals first abstract hydrogen atoms from the LLDPE molecular chain, generating LLDPE macromolecular free radicals. The vinyl ends of the trap bridging agent are activated in the free radical environment, undergoing a preliminary grafting reaction with the LLDPE macromolecular free radicals. The double bonds of TAIC also begin to undergo a small amount of crosslinking with the LLDPE free radicals, forming a localized, small-scale network structure. Simultaneously, the hydroxyl groups (-OH) on the surface of BNNS-OH undergo a condensation reaction with the silanol ends of the trap bridging agent, generating a small amount of Si-OB covalent bonds, achieving the initial connection between BNNS-OH and the polymer matrix.

[0054] In zone three (160–170℃), the cross-linking reaction is accelerated and the network expands. The decomposition rate of DCP increases significantly, and a large number of free radicals cause a surge in the concentration of free radicals in the LLDPE macromolecule, leading to dense cross-linking reactions with the multiple double bonds of TAIC, expanding the local network structure into a continuous three-dimensional network. The vinyl end grafting reaction of the trap bridging agent proceeds fully, and the condensation reaction between its other end and BNNS-OH also tends to be complete, firmly anchoring BNNS-OH in the LLDPE network. The ester groups in the TAIC molecule begin to form dynamic covalent bonds, endowing the network with reversible recombination capabilities. At this point, the cross-linking density of the material increases rapidly, and the system transitions from the molten state to an elastomer.

[0055] In zone four (170–180℃), the cross-linking network is perfected and functional groups are fixed. The three-dimensional network structure is basically formed. The remaining DCP free radicals continue to drive the unreacted LLDPE segments to react with TAIC and the trap bridging agent, so that the cross-linking density reaches a stable value. The carbazole core of the trap bridging agent is evenly distributed in the network, especially at the interface between LLDPE and BNNS-OH, forming stable deep-level trap sites. The antioxidant begins to play its role at high temperature, capturing residual free radicals and inhibiting oxidation side reactions. In this stage, the integrity of the network structure and the distribution of functional groups are basically determined.

[0056] The die head (175-185℃) is the stage for structural stabilization and granulation. At the highest processing temperature, the crosslinking reaction tends to terminate, and the dynamic covalent bonds are in a relatively stable state. The shearing action of the screw ensures the uniformity of the final system, and BNNS-OH forms a continuous heat-conducting channel in the network. After the material is extruded through the die head, it is rapidly cooled, and the three-dimensional dynamic crosslinking network is solidified and shaped. Finally, cable material particles with insulation, thermal conductivity, stability and recyclability are obtained through granulation.

[0057] Throughout the process, the screw speed of 150–350 r / min, by controlling the shear intensity, ensured the uniform dispersion of each component and provided appropriate contact opportunities for the chemical reaction. Combined with gradient heating, the orderly process of “melting and dispersion → free radical initiation → cross-linking construction → network improvement → stabilization” was achieved, ultimately forming a three-dimensional dynamic cross-linked network with synergistic structure and function.

[0058] In summary, the cable material and its preparation method provided in this application have the following advantages: (1) Material properties: Achieve synergistic effects of "insulation-thermal conduction-stability-recyclability" and break through the industry's performance bottleneck.

[0059] Traditional cable materials often face core challenges such as "difficulty in balancing thermal conductivity and insulation", "inability to recycle cross-linked materials", and "performance degradation under long-term high temperatures". This application, however, achieves simultaneous improvement of four key properties through precise component division and molecular-level synergy.

[0060] In terms of the synergy between thermal conductivity and insulation, the "bidirectional covalent bond connection" design of the trap bridging agent is used to firmly anchor the highly thermally conductive hydroxylated boron nitride nanosheets (BNNS-OH) in the polymer network. This not only significantly reduces the interfacial thermal resistance (constructing an efficient "thermal highway" to solve the problem of inefficient thermal conductivity), but also suppresses the accumulation of interfacial space charge through the deep-level traps introduced by the carbazole structure (avoiding a decrease in insulation performance), thus breaking the industry dilemma that "high thermal conductivity inevitably leads to a decrease in insulation".

[0061] In terms of balancing stability and recyclability, the compound system of antioxidants 1010 and 168, combined with the antioxidant capacity of the carbazole structure in the trap bridging agent, forms a triple protection of "capturing free radicals + decomposing hydrogen peroxide + bonded antioxidants". This effectively protects the polymer chain, dynamic cross-linking bonds, and interfacial covalent bonds from thermo-oxidative aging, ensuring the stability of the material's performance after long-term high-temperature operation. At the same time, the dynamic covalent bonds introduced by triallyl isocyanurate (TAIC) enable the cross-linked material to be reprocessed at high temperatures, solving the environmental pain point of traditional cross-linked polymers being "non-recyclable after one molding", thus balancing long-term stability and resource recycling.

[0062] (2) Structural design: The innovative “three-dimensional dynamic cross-linking network + functional hub” architecture gives the material precise functional control capabilities.

[0063] The core innovation of this application lies in constructing a three-dimensional dynamic cross-linking network with "trap bridging agents" as the key hub, so as to achieve deep coupling between structure and function.

[0064] From a structural perspective, linear low-density polyethylene (LLDPE), dicumyl peroxide (DCP), and TAIC form a "stable and intelligent" matrix network. DCP precisely triggers the free radical reaction of LLDPE, while TAIC achieves cross-linking and introduces dynamic bonds through multiple double bonds, ensuring both the high-temperature mechanical strength of the material and its recyclability. Meanwhile, the trap bridging agent acts as a "molecular bridge," grafting the polymer network at the vinyl end and connecting BNNS-OH at the siloxane end, upgrading the thermally conductive filler and matrix from "physical mixing" to "covalent integration," avoiding problems such as filler agglomeration and interface defects in traditional materials, and improving structural uniformity and stability.

[0065] From a functional perspective, the carbazole core of the trap bridging agent is not simply mixed into the system, but is fixed by covalent bonds at the interface between LLDPE and BNNS-OH (the region most prone to space charge accumulation), achieving precise positioning of the "deep-level trap" and maximizing the insulation performance. At the same time, the size (sheet thickness 10-100 nm, sheet diameter 1-10 μm) and content (10-15 parts) of BNNS-OH are optimized to form a continuous thermally conductive channel without damaging the matrix insulation, achieving "on-demand distribution" and "high-efficiency action" of functional groups.

[0066] (3) Preparation process: It takes into account "high efficiency, controllability and universality" and is suitable for industrial mass production.

[0067] The preparation process described in this application, from raw material pretreatment to final granulation, is designed around the principles of "reducing costs, improving efficiency, and ensuring quality," and has significant industrialization potential.

[0068] In the raw material preparation stage, the hydroxylated boron nitride nanosheets adopt a two-step method of "pre-oxidation with concentrated nitric acid + deep hydroxylation with hydrogen peroxide". This method does not require complex equipment (only a reflux device and a high-pressure reactor are needed). The hydroxyl content can be precisely controlled by adjusting the temperature (60-120℃), pressure (0.1-2.0MPa), and time (6-24h), avoiding the problems of low efficiency and sheet damage in traditional exfoliation methods (such as ultrasonic exfoliation). The two-step synthesis of the trap bridging agent uses conventional alkaline catalysts (anhydrous potassium carbonate / sodium carbonate) and organic solvents (N,N-dimethylformamide, acetonitrile, etc.). The reaction conditions are mild (70-100℃), and the post-processing is simple (concentration + column chromatography), making it easy to purify and producing products with high purity.

[0069] In the material forming process, the mature process of "high-speed premixing + twin-screw extrusion" is adopted: premixing at 40-60℃ for 5-15 minutes can achieve initial dispersion of components, avoiding uneven mixing at low temperature or premature reaction at high temperature; the five-stage gradient temperature control (140-185℃) and screw speed of 150-350r / min of the twin-screw extruder are precisely matched to the reaction process of "melting-initiation-crosslinking-setting", which not only ensures that each component reacts fully, but also avoids structural damage caused by local overheating. Moreover, twin-screw extrusion is a conventional equipment in the plastics processing industry and can be put into production without additional modification, thus lowering the industrialization threshold.

[0070] (4) Application value: It is suitable for high-requirement cable scenarios and has broad market prospects.

[0071] The cable materials described in this application are particularly suitable for applications requiring high insulation, high thermal conductivity, long lifespan, and low pollution, such as cables for new energy vehicles, high-voltage power transmission and transformation cables, and internal wiring for electronic equipment.

[0072] In the field of new energy vehicles, cables need to operate for a long time in high-temperature (engine compartment temperature can reach above 120℃) and high-voltage environments. The high thermal conductivity of this material can quickly dissipate the heat of the cable operation and avoid local overheating that could cause safety hazards. Its excellent insulation and anti-aging properties can ensure long-term electrical safety, while its recyclability is in line with the automotive industry's "low-carbon and environmentally friendly" development trend.

[0073] In the field of high-voltage power transmission and transformation, the deep-level traps of materials can suppress the accumulation of space charge, avoid the aging of electrical trees under high voltage, and extend the service life of cables. At the same time, the dynamic cross-linking structure facilitates the recycling and reprocessing of cables after they are discarded, reducing "white pollution" and conforming to the national "dual carbon" policy.

[0074] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0075] Example 1 This embodiment provides a cable material, which, by weight, is composed of the following chemical components: linear low-density polyethylene (CAS No. 9002-88-4, melt index 2.75 g / 10 min, density 0.925 g / cm³). 3): 85 parts; dicumyl peroxide (CAS No. 80-43-3): 0.8 parts; triallyl isocyanurate (CAS No. 1025-15-6): 2.0 parts; hydroxylated boron nitride nanosheets: 12.5 parts; N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether: 1.2 parts; antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (CAS No. 6683-19-8) to tris(2,4-di-tert-butylphenyl) phosphite (CAS No. 31570-04-4) mass ratio 0.35:0.45): 0.8 parts; lubricant (zinc stearate (CAS No. 557-05-1)): 0.75 parts.

[0076] The preparation method of the hydroxylated boron nitride nanosheets is as follows: Hexagonal boron nitride (CAS No. 10043-11-5) with an average sheet thickness of 55 nm and an average sheet diameter of 5.5 μm is selected and placed in concentrated nitric acid (CAS No. 7697-37-2, mass fraction 65%), and refluxed for 18 h for preliminary oxidation to obtain pretreated boron nitride; the pretreated boron nitride is dispersed in deionized water to prepare a dispersion with a mass concentration of 5% and hydrogen peroxide (CAS No. 7722-84-1, mass fraction 30%, the amount added is 1.5 times the mass of the pretreated boron nitride) is added to the dispersion, and then transferred to a reaction vessel and reacted at 90 °C and 1.05 MPa pressure for 15 h. After the reaction, solid-liquid separation is performed by centrifugation (speed 8000 r / min, time 15 min), the precipitate is collected and dried in a vacuum drying oven at 80 °C for 12 h to obtain hydroxylated boron nitride nanosheets.

[0077] The preparation method of the N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether is as follows: Under nitrogen (inert atmosphere) protection, 3-hydroxycarbazole (CAS No. 1680-69-3), anhydrous potassium carbonate (CAS No. 584-08-7) as the first basic catalyst, and N,N-dimethylformamide (CAS No. 68-12-2) as the first organic solvent were added to a dry three-necked flask. The molar ratio of 3-hydroxycarbazole, anhydrous potassium carbonate, and 3-chloropropyltriethoxysilane (CAS No. 2530-87-2) was 1:1.5:1.1. After stirring evenly, 3-chloropropyltriethoxysilane was slowly added dropwise. After the addition was complete, the temperature was raised to 90°C and the reaction was maintained at this temperature for 11.5 h. After the reaction was completed, the reaction solution was filtered to remove insoluble impurities. The filtrate was distilled under reduced pressure (temperature 80°C, vacuum degree 0.09 MPa) to remove the solvent, yielding crude 3-(3-triethoxysilylpropoxy)carbazole. After recrystallization from ethanol, pure 3-(3-triethoxysilylpropoxy)carbazole was obtained.

[0078] Under nitrogen (inert atmosphere) protection, the 3-(3-triethoxysilylpropoxy)carbazole prepared above, the second basic catalyst anhydrous potassium carbonate, and the second organic solvent tetrahydrofuran (CAS No. 109-99-9) were added to another dry three-necked flask. The molar ratio of 3-(3-triethoxysilylpropoxy)carbazole, anhydrous potassium carbonate, and p-vinylbenzyl chloride (CAS No. 1585-17-7) was 1:1.35:1.0. After stirring evenly, p-ethylene was slowly added dropwise. After the addition of benzyl chloride was complete, the temperature was raised to 77.5℃ and the reaction was maintained for 9 hours. After the reaction was completed, the reaction solution was filtered, and the filtrate was concentrated to 1 / 5 of the original volume by vacuum distillation (temperature 60℃, vacuum degree 0.09MPa). Then, column chromatography was performed for purification (stationary phase was silica gel, and the eluent was a mixture of petroleum ether and ethyl acetate in a volume ratio of 5:1). The target fraction was collected and the eluent was removed by vacuum distillation to obtain N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether.

[0079] Based on the above-mentioned cable material, this embodiment also provides a method for its preparation, including the following steps: Weigh the linear low-density polyethylene, dicumyl peroxide, triallyl isocyanurate, hydroxylated boron nitride nanosheets, N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether, antioxidant, and lubricant according to the above-mentioned mass proportions. Add all components to a high-speed mixer, set the mixing temperature to 50°C, the mixing time to 10 min, and the stirring speed to 3000 r / min. After thorough mixing, a premix is ​​obtained.

[0080] The premixed material is added to a twin-screw extruder, and the processing temperature of the twin-screw extruder is set to five-stage control: zone 1 145℃, zone 2 155℃, zone 3 165℃, zone 4 175℃, and die head 180℃. The screw speed is 250 r / min. After melt blending (residence time 3 min) and reactive extrusion (reaction temperature is consistent with the processing temperature of the corresponding zone), the premixed material is extruded through the extruder die head and pelletized by a pelletizer (average particle size 3 mm, average length 3 mm) to obtain the cable material. Example 2

[0081] This embodiment provides a cable material, which, by weight, is composed of the following chemical components: linear low-density polyethylene (melt index 0.5 g / 10 min, density 0.915 g / cm³). 3): 80 parts; dicumyl peroxide: 0.6 parts; triallyl isocyanurate: 1.6 parts; hydroxylated boron nitride nanosheets: 10 parts; N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether: 0.8 parts; antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] to tris(2,4-di-tert-butylphenyl) phosphite mass ratio 0.2:0.3): 0.5 parts; lubricant (ethylene bis-stearamide): 0.5 parts.

[0082] The preparation method of the hydroxylated boron nitride nanosheets is as follows: Hexagonal boron nitride with an average sheet thickness of 10 nm and an average sheet diameter of 1 μm is selected and placed in concentrated nitric acid (mass fraction 65%), and refluxed for 12 h for preliminary oxidation to obtain pretreated boron nitride; the pretreated boron nitride is dispersed in deionized water to prepare a dispersion with a mass concentration of 4% and hydrogen peroxide (mass fraction 30%, the amount added is 1.2 times the mass of the pretreated boron nitride) is added to the dispersion, and then transferred to a reaction vessel and reacted at 60 °C and 0.1 MPa pressure for 24 h. After the reaction, solid-liquid separation is performed by centrifugation (speed 7000 r / min, time 20 min), the precipitate is collected and dried in a vacuum drying oven at 70 °C for 15 h to obtain hydroxylated boron nitride nanosheets.

[0083] The preparation method of the N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether is as follows: Under nitrogen protection, 3-hydroxycarbazole, anhydrous sodium carbonate as the first basic catalyst, and dimethyl sulfoxide as the first organic solvent were added to a dry three-necked flask. The molar ratio of 3-hydroxycarbazole, anhydrous sodium carbonate, and 3-chloropropyltriethoxysilane was 1:1.2:1.0. After stirring until homogeneous, 3-chloropropyltriethoxysilane was slowly added dropwise. After the addition was complete, the temperature was raised to 80°C and the reaction was maintained at this temperature for 15 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble impurities. The filtrate was distilled under reduced pressure (temperature 75°C, vacuum degree 0.08 MPa) to remove the solvent, yielding crude 3-(3-triethoxysilylpropoxy)carbazole. After recrystallization from ethanol, pure 3-(3-triethoxysilylpropoxy)carbazole was obtained.

[0084] Under nitrogen protection, 3-(3-triethoxysilylpropoxy)carbazole, anhydrous sodium carbonate as a second basic catalyst, and acetonitrile as a second organic solvent were added to another dry three-necked flask. The molar ratio of 3-(3-triethoxysilylpropoxy)carbazole, anhydrous sodium carbonate, and p-vinylbenzyl chloride was 1:1.2:0.8. After stirring evenly, p-vinylbenzyl chloride was slowly added dropwise. After the addition was complete, the temperature was raised to 70°C and the reaction was maintained at this temperature for 12 hours. After the reaction was completed, the reaction solution was filtered, and the filtrate was concentrated to 1 / 6 of its original volume by vacuum distillation (temperature 55°C, vacuum degree 0.08 MPa). Then, column chromatography was performed for purification (stationary phase was silica gel, and the eluent was a mixture of petroleum ether and ethyl acetate in a volume ratio of 6:1). The target fraction was collected and the eluent was removed by vacuum distillation to obtain N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether.

[0085] Based on the above-mentioned cable material, this embodiment also provides a method for its preparation, including the following steps: Weigh each component according to the above mass percentages, add all components to a high-speed mixer, set the mixing temperature to 40℃, the mixing time to 15min, and the stirring speed to 2500r / min, and obtain the premix after thorough mixing.

[0086] The premixed material is added to a twin-screw extruder, and the processing temperature of the twin-screw extruder is set to five-stage control: zone 1 140℃, zone 2 150℃, zone 3 160℃, zone 4 170℃, and die head 175℃. The screw speed is 150 r / min. After melt blending (residence time 4 min) and reactive extrusion, the premixed material is extruded through the extruder die head and pelletized by a pelletizer (average particle size 2.5 mm, average length 2.5 mm) to obtain the cable material.

[0087] Example 3 This embodiment provides a cable material, which, by weight, is composed of the following chemical components: linear low-density polyethylene (melt index 4 g / 10 min, density 0.930 g / cm³). 3 ): 88 parts; dicumyl peroxide: 0.9 parts; triallyl isocyanurate: 2.2 parts; hydroxylated boron nitride nanosheets: 14 parts; N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether: 1.5 parts; antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] to tris(2,4-di-tert-butylphenyl) phosphite mass ratio 0.45:0.55): 1.0 parts; lubricant (silicone lubricant): 0.9 parts.

[0088] The preparation method of the hydroxylated boron nitride nanosheets is as follows: Hexagonal boron nitride with an average sheet thickness of 80 nm and an average sheet diameter of 8 μm is selected and placed in concentrated nitric acid (mass fraction 65%), and refluxed for 22 h for preliminary oxidation to obtain pretreated boron nitride; the pretreated boron nitride is dispersed in deionized water to prepare a dispersion with a mass concentration of 6% and hydrogen peroxide (mass fraction 30%, the amount added is 1.8 times the mass of the pretreated boron nitride) is added to the dispersion, and then transferred to a reaction vessel and reacted at 110 °C and 1.8 MPa pressure for 8 h. After the reaction, solid-liquid separation is performed by centrifugation (speed 9000 r / min, time 12 min), the precipitate is collected and dried in a vacuum drying oven at 85 °C for 10 h to obtain hydroxylated boron nitride nanosheets.

[0089] The preparation method of the N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether is as follows: Under nitrogen protection, 3-hydroxycarbazole, anhydrous potassium carbonate as the first basic catalyst, and acetonitrile as the first organic solvent were added to a dry three-necked flask. The molar ratio of 3-hydroxycarbazole, anhydrous potassium carbonate, and 3-chloropropyltriethoxysilane was 1:1.7:1.15. After stirring evenly, 3-chloropropyltriethoxysilane was slowly added dropwise. After the addition was complete, the temperature was raised to 95°C and the reaction was maintained at this temperature for 10 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble impurities. The filtrate was distilled under reduced pressure (temperature 85°C, vacuum degree 0.095 MPa) to remove the solvent, yielding crude 3-(3-triethoxysilylpropoxy)carbazole. After recrystallization from ethanol, pure 3-(3-triethoxysilylpropoxy)carbazole was obtained.

[0090] Under nitrogen protection, 3-(3-triethoxysilylpropoxy)carbazole, anhydrous potassium carbonate as a second basic catalyst, and acetone as a second organic solvent were added to another dry three-necked flask. The molar ratio of 3-(3-triethoxysilylpropoxy)carbazole, anhydrous potassium carbonate, and p-vinylbenzyl chloride was 1:1.45:1.15. After stirring evenly, p-vinylbenzyl chloride was slowly added dropwise. After the addition was complete, the temperature was raised to 82°C and the reaction was maintained for 7 hours. After the reaction was completed, the reaction solution was filtered, and the filtrate was concentrated to 1 / 4 of its original volume by vacuum distillation (temperature 65°C, vacuum degree 0.095MPa). Then, column chromatography was performed for purification (stationary phase was silica gel, and the eluent was a mixture of petroleum ether and ethyl acetate in a volume ratio of 4:1). The target fraction was collected and the eluent was removed by vacuum distillation to obtain N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether.

[0091] Based on the above-mentioned cable material, this embodiment also provides a method for its preparation, including the following steps: Weigh each component according to the above mass percentages, add all components to a high-speed mixer, set the mixing temperature to 55℃, the mixing time to 7 minutes, and the stirring speed to 3500 r / min, and obtain the premix after thorough mixing.

[0092] The premixed material is added to a twin-screw extruder, and the processing temperature of the twin-screw extruder is set to five-stage control: zone 1 148℃, zone 2 158℃, zone 3 168℃, zone 4 178℃, and die head 183℃. The screw speed is 320 r / min. After melt blending (residence time 2.5 min) and reactive extrusion, the premixed material is extruded through the extruder die head and pelletized by a pelletizer (average particle size 3.5 mm, average length 3.5 mm) to obtain the cable material.

[0093] Example 4 This embodiment provides a cable material, which, by weight, is composed of the following chemical components: linear low-density polyethylene (melt index 5 g / 10 min, density 0.935 g / cm³). 3 ): 90 parts; dicumyl peroxide: 1.0 part; triallyl isocyanurate: 2.4 parts; hydroxylated boron nitride nanosheets: 15 parts; N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether: 1.6 parts; antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] to tris(2,4-di-tert-butylphenyl) phosphite mass ratio 0.5:0.5): 1.0 part; lubricant (zinc stearate to silicone lubricant mass ratio 1:1): 1.0 part.

[0094] The preparation method of the hydroxylated boron nitride nanosheets is as follows: Hexagonal boron nitride with an average sheet thickness of 100 nm and an average sheet diameter of 10 μm is selected and placed in concentrated nitric acid (mass fraction 65%), and refluxed for 24 h for preliminary oxidation to obtain pretreated boron nitride; the pretreated boron nitride is dispersed in deionized water to prepare a dispersion with a mass concentration of 7% and hydrogen peroxide (mass fraction 30%, the amount added is 2.0 times the mass of the pretreated boron nitride) is added to the dispersion, and then transferred to a reaction vessel and reacted at 120 °C and 2.0 MPa pressure for 6 h. After the reaction, solid-liquid separation is performed by centrifugation (speed 10000 r / min, time 10 min), the precipitate is collected and dried in a vacuum drying oven at 90 °C for 8 h to obtain hydroxylated boron nitride nanosheets.

[0095] The preparation method of the N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether is as follows: Under nitrogen protection, 3-hydroxycarbazole, anhydrous sodium carbonate as the first basic catalyst, and N,N-dimethylformamide as the first organic solvent were added to a dry three-necked flask. The molar ratio of 3-hydroxycarbazole, anhydrous sodium carbonate, and 3-chloropropyltriethoxysilane was 1:1.8:1.2. After stirring until homogeneous, 3-chloropropyltriethoxysilane was slowly added dropwise. After the addition was complete, the temperature was raised to 100°C and the reaction was maintained at this temperature for 8 hours. After the reaction was completed, the reaction solution was filtered to remove insoluble impurities. The filtrate was distilled under reduced pressure (90°C, 0.1 MPa) to remove the solvent, yielding crude 3-(3-triethoxysilylpropoxy)carbazole. After recrystallization from ethanol, pure 3-(3-triethoxysilylpropoxy)carbazole was obtained.

[0096] Under nitrogen protection, 3-(3-triethoxysilylpropoxy)carbazole, anhydrous sodium carbonate as a second basic catalyst, and tetrahydrofuran as a second organic solvent were added to another dry three-necked flask. The molar ratio of 3-(3-triethoxysilylpropoxy)carbazole, anhydrous sodium carbonate, and p-vinylbenzyl chloride was 1:1.5:1.2. After stirring evenly, p-vinylbenzyl chloride was slowly added dropwise. After the addition was complete, the temperature was raised to 85°C and the reaction was maintained for 6 hours. After the reaction was completed, the reaction solution was filtered, and the filtrate was concentrated to 1 / 3 of the original volume by vacuum distillation (temperature 70°C, vacuum degree 0.1MPa). Then, column chromatography was performed for purification (stationary phase was silica gel, and the eluent was a mixture of petroleum ether and ethyl acetate in a volume ratio of 3:1). The target fraction was collected and the eluent was removed by vacuum distillation to obtain N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether.

[0097] Based on the above-mentioned cable material, this embodiment also provides a method for its preparation, including the following steps: Weigh each component according to the above mass percentages, add all components to a high-speed mixer, set the mixing temperature to 60℃, the mixing time to 5 min, and the stirring speed to 4000 r / min, and obtain the premix after thorough mixing.

[0098] The premixed material is added to a twin-screw extruder, and the processing temperature of the twin-screw extruder is set to five-stage control: zone 1 150℃, zone 2 160℃, zone 3 170℃, zone 4 180℃, and die head 185℃. The screw speed is 350 r / min. After melt blending (residence time 2 min) and reactive extrusion, the premixed material is extruded through the extruder die head and pelletized by a pelletizer (average particle size 4 mm, average length 4 mm) to obtain the cable material.

[0099] Comparative Example 1 This comparative example is modified from the one disclosed in Example 1 as follows: The chemical composition of the cable material does not contain dicumyl peroxide.

[0100] Comparative Example 2 This comparative example is modified from the one disclosed in Example 1 as follows: The cable material does not contain triallyl isocyanurate in its chemical composition.

[0101] Comparative Example 3 This comparative example is modified from the one disclosed in Example 1 as follows: The chemical composition of the cable material does not contain hydroxylated boron nitride nanosheets.

[0102] Comparative Example 4 This comparative example is modified from the one disclosed in Example 1 as follows: The hydroxylated boron nitride nanosheets in the chemical composition of the cable material were replaced with an equal mass of untreated boron nitride nanosheets (average sheet thickness 55 nm, average sheet diameter 5.5 μm, CAS No. 10043-11-5).

[0103] Comparative Example 5 This comparative example is modified from the one disclosed in Example 1 as follows: The chemical composition of the cable material does not contain N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether.

[0104] Comparative Example 6 This comparative example is modified from the one disclosed in Example 1 as follows: Replace N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether in the chemical composition of the cable material with an equal mass of silane coupling agent KH550.

[0105] Comparative Example 7 This comparative example is modified from the one disclosed in Example 1 as follows: The chemical composition of the cable material does not contain hydroxylated boron nitride nanosheets or N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether.

[0106] The cable materials obtained in Examples 1-4 and Comparative Examples 1-7 were subjected to performance tests, and the results are shown in Tables 1 and 2. The performance test methods are as follows: Standard for measuring insulation performance (volume resistivity): GB / T 1410-2006; Standard for measuring thermal conductivity: GB / T 10297-2015; The standard for testing tensile strength and elongation at break is GB / T 1040.1.

[0107] The standard for the Hot Set Test is GB / T 2951.21.

[0108] Stability (tensile strength retention rate after thermo-oxidative aging) test standard: GB / T 2951.12-2008; Recyclability (tensile strength retention rate after thermal cycling) determination method: Take the initially prepared cable material particles, perform the first extrusion granulation according to the extrusion process of Example 1, process them into samples and measure the tensile strength (σ1); perform the second extrusion granulation of the particles after the first extrusion according to the same process, process them into samples and measure the tensile strength (σ2); repeat the above operation until the fifth extrusion, and measure the tensile strength (σ5); calculate the tensile strength retention rate after the fifth processing: (σ5 / σ1)×100%, test each sample 5 times and take the average value.

[0109]

[0110]

[0111] As shown in Tables 1 and 2, the volume resistivity of the cable materials in Examples 1-4 is 5.8 × 10⁻⁶. 15 ~7.0×10 15 Ω·m, thermal conductivity 0.65–0.9 W / (m·K), tensile strength 20.1–24.5 MPa, elongation at break 435.5–524.5%; in the heat extension performance (200℃ / 15min), the elongation under load is 47.8–64.5%, and the permanent deformation after cooling is 3.3–8.1%; the tensile strength retention rate after thermo-oxidative aging is 91.8–94.1%, and the tensile strength retention rate after 5 thermal cycles is 81.1–88.3%.

[0112] Comparative Example 1, lacking the crosslinking agent dicumyl peroxide (DCP), could not form a stable three-dimensional crosslinked network, and the material only exhibited thermoplastic properties: the worst thermal elongation performance and fracture occurred, and the volume resistivity dropped significantly to 1.2 × 10¹. 4 With a thermal conductivity as low as 0.35 W / (m·K) and a tensile strength of only 15.3 MPa, its mechanical strength and insulation properties are significantly reduced. It retains only 100% recyclability, but the lack of core performance results in extremely low practical value.

[0113] Comparative Example 2 lacks the dynamic crosslinking agent triallyl isocyanurate (TAIC), and the crosslinking network relies entirely on irreversible C-C bonds for construction: in the 200℃ / 15min thermal extension test, the permanent deformation upon cooling reached 25.4%, and the dimensional stability was insufficient at high temperatures due to the lack of dynamic bond rearrangement ability; although the tensile strength retention rate reached 92.1% after 5 thermal cycles and the recyclability was good, the material had lost its practical use due to severe deformation.

[0114] Comparative Example 3 lacks a core thermally conductive filler, hydroxylated boron nitride nanosheets (h-BN), which prevents the construction of an effective thermal conduction pathway within the material. Heat can only be slowly conducted through the resin matrix, resulting in a thermal conductivity as low as 0.42 W / (m・K), far below the level of the example, and thus failing to meet the heat dissipation requirements of the cable.

[0115] Comparative Example 4 uses unhydroxylated boron nitride nanosheets, which have poor compatibility with the polymer matrix and are prone to agglomeration. On the one hand, this increases the interfacial thermal resistance, with a thermal conductivity of only 0.55 W / (m・K), resulting in limited improvement in thermal conductivity. On the other hand, it weakens the interfacial bonding force, and the agglomeration area becomes a stress concentration point, reducing the tensile strength to 18.0 MPa and decreasing the mechanical strength. The uneven local structure also leads to a slight reduction in insulation performance.

[0116] Comparative Example 5 lacks the "bridging" component N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether: it cannot capture charge through the carbazole group, and its volume resistivity is only 4.0 × 10¹. 5 Ω・m, the worst insulation; cannot optimize interface compatibility, thermal conductivity 0.62W / (m・K), tensile strength 17.8MPa, limited improvement in thermal conductivity and mechanical strength; at the same time, it loses the auxiliary antioxidant effect of carbazole group, and the overall performance is comprehensively reduced.

[0117] Comparative Example 6 uses the common silane coupling agent KH550 instead of the dedicated silane ether. KH550 can only provide basic interfacial coupling: because it does not contain a carbazole group, it cannot introduce deep-level traps to suppress space charge, and its volume resistivity is 4.5 × 10¹. 5 Ω・m, insulation is significantly lower than in the example; it does not contain vinyl, cannot participate in the crosslinking network, has poor bonding strength with the matrix, and its overall performance is inferior to that of the example.

[0118] Comparative Example 7, lacking both h-BN and a dedicated silane ether, exhibits neither thermally conductive fillers to construct thermally conductive pathways, resulting in a thermal conductivity as low as 0.38 W / (m·K); nor compatibilizers to enhance insulation, leading to a volume resistivity of only 3.8 × 10¹. 5 Ω・m; Material properties reverted to the level of a simple mixture of matrix resin and additives, with insulation and thermal conductivity being the worst among all comparative examples.

[0119] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0120] Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0121] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A cable material, characterized in that, By weight, the cable material is composed of the following chemical components: linear low-density polyethylene: 80-90 parts, dicumyl peroxide: 0.6-1.0 parts, triallyl isocyanurate: 1.6-2.4 parts, hydroxylated boron nitride nanosheets: 10-15 parts, N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether: 0.8-1.6 parts, antioxidant: 0.4-1.1 parts, lubricant: 0.5-1 parts; The preparation method of the N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether includes: Under an inert atmosphere, 3-hydroxycarbazole, a first basic catalyst and a first organic solvent were mixed, and 3-chloropropyltriethoxysilane was slowly added. The mixture was reacted at 80-100°C for 8-15 hours, and 3-(3-triethoxysilylpropoxy)carbazole was obtained after post-treatment. Under an inert atmosphere, the 3-(3-triethoxysilylpropoxy)carbazole, the second basic catalyst, and the second organic solvent were mixed, and p-vinylbenzyl chloride was slowly added. The mixture was reacted at 70–85 °C for 6–12 h. The reaction solution was concentrated and purified by column chromatography to obtain the N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether. The method for preparing the hydroxylated boron nitride nanosheets includes: Hexagonal boron nitride was refluxed in concentrated nitric acid for 12–24 h to carry out preliminary oxidation and obtain pretreated boron nitride. Hydrogen peroxide was added to the pretreated boron nitride dispersion, and then the reaction was carried out at 60–120 °C and 0.1–2.0 MPa for 6–24 h. The reaction solution was then separated into solid and liquid phases to obtain the hydroxylated boron nitride nanosheets.

2. The cable material according to claim 1, characterized in that, The linear low-density polyethylene has a melt index of 0.5–5 g / 10 min and a density of 0.915–0.935 g / cm³. 3 .

3. The cable material according to claim 1, characterized in that, The antioxidant is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl) phosphite, wherein the mass ratio of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] to tris(2,4-di-tert-butylphenyl) phosphite is (0.2-0.5):(0.3-0.6).

4. The cable material according to claim 1, characterized in that, The lubricant includes one or more of zinc stearate, ethylene bis-stearamide, and silicone lubricants.

5. The cable material according to claim 1, characterized in that, The thickness of the hexagonal boron nitride sheets is 10–100 nm, and the sheet diameter is 1–10 μm.

6. The cable material according to claim 1, characterized in that, The first alkaline catalyst is anhydrous potassium carbonate or anhydrous sodium carbonate; The second alkaline catalyst is anhydrous potassium carbonate or anhydrous sodium carbonate; The first organic solvent is N,N-dimethylformamide, dimethyl sulfoxide, or acetonitrile; The molar ratio of the 3-hydroxycarbazole, the first alkaline catalyst, and the 3-chloropropyltriethoxysilane is 1:(1.2-1.8):(1.0-1.2). The second organic solvent is acetonitrile, tetrahydrofuran, or acetone; The molar ratio of the 3-(3-triethoxysilylpropoxy)carbazole, the second basic catalyst, and the p-vinylbenzyl chloride is 1:(1.2-1.5):(0.8-1.2).

7. A method for preparing the cable material according to any one of claims 1 to 6, characterized in that, The method includes: Linear low-density polyethylene, dicumyl peroxide, triallyl isocyanurate, hydroxylated boron nitride nanosheets, N-(vinylbenzyl)carbazole-3-(triethoxysilyl)propyl ether, antioxidant and lubricant are mixed at high speed and at 40-60°C for 5-15 min to obtain a premix. The premixed material is added to a twin-screw extruder, and after melt blending, reactive extrusion, and granulation, the cable material is obtained.

8. The method for preparing cable material according to claim 7, characterized in that, The processing temperature of the twin-screw extruder is controlled in five zones: Zone 1 is 140-150℃, Zone 2 is 150-160℃, Zone 3 is 160-170℃, Zone 4 is 170-180℃, and the die head is 175-185℃. The screw speed is 150-350 r / min.

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