Bending-resistant heat-resistant flame-retardant cable and preparation method thereof

Abstract

The invention relates to the technical field of wire and cable manufacturing, in particular to a bending-resistant heat-resistant flame-retardant cable and a preparation method thereof. The bending-resistant heat-resistant flame-retardant cable sequentially comprises a cable core, a shielding layer and an outer sheath layer from inside to outside, the outer sheath layer is prepared from the following raw materials in parts by mass: 40 to 45 parts of polyvinylidene fluoride, 65 to 70 parts of ethylene-vinyl acetate copolymer, 15 to 18 parts of flame retardant, 30 to 35 parts of heat-conducting reinforcing filler, 1.5 to 2 parts of coupling agent, 1 to 1.5 parts of antioxidant, 1 to 1.5 parts of lubricant and 2 to 2.5 parts of flexibilizer. The outer sheath layer prepared by the invention has excellent mechanical strength, toughness, heat-conducting property, high temperature resistance and flame retardant property, and the prepared wire and cable are suitable for power transmission and signal transmission in a high-temperature environment, especially in an application scene with frequent bending and high temperature change. The invention relates to the fields of aerospace, industrial automation equipment, automotive electronic systems and the like.

Description

Technical Field

[0001] This application relates to the technical field of wire and cable manufacturing, and in particular to a bend-resistant, heat-resistant and flame-retardant cable and a preparation method thereof. Background Art

[0002] Currently, cables on the market usually consist of a conductor, an insulating layer, a sheath, etc. Common materials include copper and aluminum as conductors, and PVC, PE, XLPE, etc. as insulating materials. Although these traditional cables have stable performance in ordinary environments, they are prone to problems such as aging and cracking under high temperature and frequent bending, resulting in a decline or even failure of electrical performance. With the development of technology, more and more industries have put forward higher requirements for the temperature resistance, flame retardancy and bend resistance of cables. Especially in fields such as aerospace and industrial automation, traditional cables can no longer meet the needs. Summary of the Invention

[0003] Aiming at the deficiencies of the existing technology, this application provides a bend-resistant, heat-resistant and flame-retardant cable and a preparation method thereof. The outer sheath layer prepared by this application has excellent mechanical strength, toughness, thermal conductivity, high-temperature resistance and flame-retardant properties. The prepared wire and cable are suitable for power transmission and signal transmission in high-temperature environments, especially in application scenarios with frequent bending and high temperature changes, such as aerospace, industrial automation equipment, automotive electronic systems and other fields.

[0004] In the first aspect, this application provides a bend-resistant, heat-resistant and flame-retardant cable, adopting the following technical solution: A bend-resistant, heat-resistant and flame-retardant cable, which sequentially includes a cable core, a shielding layer and an outer sheath layer from the inside to the outside; the cable core is made by covering a copper core with a low-density polyethylene film; the shielding layer is made by covering the cable core with aluminum foil; the outer sheath layer, by mass, includes the following preparation raw materials: 40-45 parts of polyvinylidene fluoride, 65-70 parts of ethylene-vinyl acetate copolymer, 15-18 parts of flame retardant, 30-35 parts of thermally conductive reinforcing filler, 1.5-2 parts of coupling agent, 1-1.5 parts of antioxidant, 1-1.5 parts of lubricant, 2-2.5 parts of toughening agent. Among them, the flame retardant is prepared by mixing a modified flame retardant phosphate ester and a modified thermally conductive flame retardant, and the thermally conductive reinforcing filler includes modified glass fiber, modified boron nitride nanosheet, nanocellulose and graphene oxide.

[0005] By adopting the above technical solution, the cable core is mainly composed of a copper core and a low-density polyethylene film. The copper core is responsible for the transmission of current, while the low-density polyethylene film plays a role in protecting the copper core and improving flexibility. The shielding layer is made of aluminum foil, and its main function is to prevent electromagnetic interference and radiation, protecting the signal transmission inside the cable from external interference. Outer sheath layer: The outer sheath layer is a key part of the cable, and its composition and synergistic effects are as follows: Polyvinylidene fluoride and ethylene-vinyl acetate copolymer: These two materials provide the basic mechanical strength and chemical corrosion resistance of the cable. The flame retardant is prepared by mixing a modified flame retardant phosphate ester and a modified thermally conductive flame retardant. Its main function is to improve the flame retardant performance of the cable. At the same time, the synergistic effect of the modified flame retardant phosphate ester and the modified thermally conductive flame retardant further enhances the flame retardant effect. Thermally conductive reinforcing fillers: including modified glass fibers, modified boron nitride nanosheets, nanocellulose, and graphene oxide. These materials produce a synergistic effect during the melt extrusion process, significantly enhancing the thermal conductivity and mechanical properties of the cable. Coupling agents, antioxidants, lubricants, and toughening agents: These additives help improve the overall performance of the cable, including improving the processing performance of the material, enhancing the aging resistance and flexibility of the cable. In summary, the components in this application jointly improve the comprehensive performance of the cable through synergistic effects, enabling it to exhibit excellent mechanical properties, toughness, thermal conductivity, high-temperature resistance, and flame retardant performance in power transmission and signal transmission under high-temperature environments.

[0006] Preferably, the mass ratio of the modified flame retardant phosphate ester to the modified thermally conductive flame retardant is 4:7-9.

[0007] By adopting the above technical solutions, the synergistic effect of the modified flame-retardant phosphate ester and the modified heat-conducting flame retardant can significantly improve the flame-retardant performance of the cable outer sheath layer. The modified flame-retardant phosphate ester provides good flame-retardant effects, while the modified heat-conducting flame retardant enhances the flame-retardant performance through its organic-inorganic hybrid structure and the characteristics of nanomaterials. The phosphazene molecular structure in the modified heat-conducting flame retardant can remain stable at high temperatures, thereby improving the high-temperature resistance of the cable. At the same time, the synergistic effect of the modified flame-retardant phosphate ester and the modified heat-conducting flame retardant further enhances this high-temperature resistance. The synergistic effect of the modified flame-retardant phosphate ester and the modified heat-conducting flame retardant can also improve the mechanical properties of the cable outer sheath layer. The fluorine element and benzene ring structure in the modified flame-retardant phosphate ester and the organic-inorganic hybrid structure in the modified heat-conducting flame retardant both contribute to improving the strength and toughness of the material. The combined use of modified boron nitride nanosheets and graphene oxide can significantly enhance the heat-conducting performance of the cable outer sheath layer. At the same time, the synergistic effect of the modified flame-retardant phosphate ester and the modified heat-conducting flame retardant further improves this heat-conducting performance. In summary, when the mass fraction ratio of the modified flame-retardant phosphate ester to the modified heat-conducting flame retardant is 4:7-9, it can maintain good flame-retardant performance of the cable outer sheath layer while improving its high-temperature resistance, mechanical properties, and heat-conducting performance, making it suitable for power transmission and signal transmission in high-temperature environments.

[0008] Preferably, the preparation method of the modified flame-retardant phosphate ester includes the following steps: S31. According to the mass fraction, mix 238 parts of pentafluorophenyl acrylate and 120 parts of mercaptoethanol evenly, then add 4 parts of photoinitiator 1173, and react under ultraviolet light irradiation of 50 mW / cm 2 for 1-2 h, collect the product to obtain a hydroxyl-containing fluorine monomer; S32. According to the mass fraction, mix 347 parts of hexachlorocyclotriphosphazene, 1400 parts of hydroxyl-containing fluorine monomer, 560 parts of potassium carbonate, 96.6 parts of tetrabutylammonium bromide, and 3000 parts of acetone, stir for 30-40 min under a nitrogen atmosphere, heat up to 55-60 °C, reflux and react for 40-44 h, cool after the reaction, filter to remove potassium carbonate, rotary evaporate to remove acetone, collect the product, and vacuum dry at 40 °C to obtain a flame-retardant phosphate ester; S33. According to the mass fraction, add 100 parts of the flame-retardant phosphate ester and 3.3 parts of γ-(methacryloyloxy)propyltrimethoxysilane to 200 parts of acetone. At the same time, under nitrogen protection, heat up to 75 °C and keep warm for 2 h. Then, dissolve 0.3 parts of azodiisooctanenitrile in 10 parts of acetone to obtain an azodiisooctanenitrile solution, slowly drop the azodiisooctanenitrile solution within 1 h, and then react for 12 h. Rotary evaporate to remove acetone to obtain a modified flame-retardant phosphate ester.

[0009] By adopting the above technical solution, a flame-retardant phosphate ester is prepared from components such as pentafluorophenyl acrylate, mercaptoethanol, and hexachlorocyclotriphosphazene, and the flame-retardant phosphate ester is modified with silane, which can significantly improve the dispersibility and compatibility of the flame-retardant phosphate ester. During the preparation, a click reaction is first carried out through the mercapto group to introduce a hydroxyl group onto the pentafluorophenyl acrylate to form a hydroxyl-containing fluorine monomer; then the introduced hydroxyl group is grafted with hexachlorocyclotriphosphazene to obtain the flame-retardant phosphate ester. The technical effects are as follows: In one aspect, the pentafluorophenyl acrylate contains fluorine elements and a benzene ring, which can improve the hydrophobic property of the outer sheath layer, thereby improving its water resistance and corrosion resistance; the introduction of the benzene ring can also improve the mechanical property of the outer sheath layer; on the other hand, the introduction of hexachlorocyclotriphosphazene can improve the flame-retardant property of the outer sheath layer.

[0010] Preferably, the preparation method of the modified thermal conductive flame retardant comprises the following steps: S41. According to the mass parts, 100 parts of hexachlorocyclotriphosphazene, 314 parts of p-acetaminophen, and 430 parts of potassium carbonate are added to 2500 parts of acetone and mixed evenly, and then the reaction is carried out at a temperature of 70 - 75 °C for 48 - 52 hours under nitrogen protection. Then the reaction product is poured into deionized water, stirred, filtered, and the obtained solid is washed successively with deionized water, n-hexane, and ethanol, and then placed in a vacuum drying oven and dried at a temperature of 60 - 70 °C for 40 - 48 hours to obtain hexakis(4-acetamidophenoxy)cyclotriphosphazene; S42. According to the mass parts; 51.8 parts of hexakis(4-acetamidophenoxy)cyclotriphosphazene, 500 parts of methanol, and 130 parts of an aqueous sodium hydroxide solution with a mass concentration of 43% are mixed evenly, and at a stirring rate of 100 rpm, the temperature is raised to 85 - 90 °C and the reaction is carried out for 40 - 48 hours. After the reaction product is cooled to room temperature, it is filtered, and the solid is washed successively with deionized water and ethanol, and then placed in a vacuum drying oven and dried at a temperature of 68 °C for 48 hours to obtain hexakis(4-aminophenoxy)cyclotriphosphazene; S43. According to the mass parts, 60 parts of hexakis(4-aminophenoxy)cyclotriphosphazene and 8.3 parts of γ-(methacryloyloxy)propyltrimethoxysilane are added to 200 parts of acetone. Meanwhile, under nitrogen protection, the temperature is heated to 75 - 80 °C and kept warm for 0.7 - 1 h. Then, 0.3 part of azodiisooctanenitrile is dissolved in 10 parts of acetone to obtain an azodiisooctanenitrile solution, and the azodiisooctanenitrile solution is slowly added dropwise within 1 h, and then the reaction is carried out for 10 - 12 h, and then the acetone is removed by rotary evaporation to obtain γ-(methacryloyloxy)propyltrimethoxysilane-modified hexakis(4-aminophenoxy)cyclotriphosphazene; S44. By mass parts, nano boron nitride with a particle size of 40 - 50 nm is dried at 100 - 120 °C for 6 - 8 h. Then, 100 parts of the dried boron nitride and 100 parts of γ-(methacryloyloxy)propyltrimethoxysilane modified hexakis(4-aminophenoxy)cyclotriphosphazene are added to 300 parts of absolute ethanol. After stirring evenly, under nitrogen protection, the mixture is refluxed at 88 - 92 °C for 10 - 12 h. After the reaction is completed, it is filtered, washed with ethanol, and dried to obtain a modified thermal conductive flame retardant.

[0011] By adopting the above technical solution, the prepared modified thermal conductive flame retardant has an organic-inorganic hybrid structure with alternating single and double bonds of phosphorus and nitrogen, and can play a good synergistic flame retardant effect; each phosphorus atom in the phosphazene molecule has two active P-N bonds, which has good designability and can synthesize different phosphazene structures. The formed cyclic crosslinked phosphazene compounds have various morphologies such as nanofibers, hollow spheres, and layered structures; due to the small size effect and high specific surface area of the nanomaterials, the nanomaterials greatly improve the flame retardant performance of the outer sheath layer. At the same time, the modified hexakis(4-aminophenoxy)cyclotriphosphazene is first modified by a silane coupling agent and then combined with nano boron nitride, greatly improving the mechanical properties, thermal conductivity, high temperature resistance, and flame retardant performance of the outer sheath layer.

[0012] Preferably, the preparation method of the thermal conductive reinforcing filler includes the following steps: S51. By mass parts, 10 parts of chopped glass fibers with a length of 4 - 6 mm and a diameter of 10 - 15 μm are placed in 200 parts of xylene, ultrasonically dispersed for 30 min, 15 parts of glycine are added, and after reflux reaction for 12 h, it is filtered, washed, and dried to obtain modified glass fibers for standby; S52. By mass parts, 10 parts of boron nitride nanosheets are dispersed in 10 parts of an ethanol aqueous solution with a concentration of 75%. After ultrasonic dispersion, a boron nitride suspension is obtained. 10 parts of tannic acid and 0.5 part of vinyltriethoxysilane are added to the boron nitride suspension, and the mixture is stirred to react. After the reaction is completed, it is filtered, washed, and dried to obtain modified boron nitride nanosheets for standby; S53. By mass parts, 10 parts of modified glass fibers, 50 parts of modified boron nitride nanosheets, and 100 parts of graphene oxide are dispersed in 4000 parts of a nanocellulose solution with a mass concentration of 0.5% and ultrasonically dispersed to obtain a filler mixture; the filler mixture is vacuum freeze-dried at 50 °C for 24 h to obtain a thermal conductive reinforcing filler.

[0013] By adopting the above technical solutions, the modified glass fiber, modified boron nitride nanosheets and graphene oxide in the thermal conductive reinforcing filler will also produce a synergistic effect during the melt extrusion process. On the one hand, the composite of modified boron nitride nanosheets and graphene oxide will significantly enhance the thermal conductivity of the outer sheath layer. This is because there is a strong hydrogen bond interaction between the modified boron nitride nanosheets and graphene oxide. Under the action of hydrogen bonds, the two-dimensional boron nitride nanosheets and one-dimensional graphene oxide can be closely stacked together after melt extrusion and are highly oriented in the plane direction, forming a "brick-mortar" layered structure. This highly oriented ordered in-plane arrangement will provide a good path for the transmission of phonons between adjacent boron nitride nanosheets, which can significantly improve the thermal conductivity of the outer sheath layer. At the same time, the mechanical properties of the outer sheath layer are further improved by the modified glass fiber. In addition, the modified glass fiber and modified boron nitride nanosheets can form good hydrogen bond interactions with nanocellulose, and the modified boron nitride nanosheets and modified glass fiber are relatively uniformly dispersed in graphene oxide and exhibit an ordered layered structure, which helps to improve the mechanical properties and thermal conductivity of the outer sheath layer.

[0014] Preferably, the coupling agent is prepared by mixing γ-(methacryloyloxy)propyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane and vinyltriethoxysilane in a mass ratio of 3:3:4.

[0015] By adopting the above technical solutions, γ-(methacryloyloxy)propyltrimethoxysilane: mainly used to improve the interfacial adhesion between inorganic fillers and organic polymers. It can react with the hydroxyl groups on the surface of inorganic fillers to form chemical bonds, thereby improving the dispersibility and compatibility of the fillers in the polymer matrix. 3-Isocyanatopropyltriethoxysilane: It can react with the hydroxyl groups on the surface of inorganic fillers to form chemical bonds. At the same time, it can also react with the active groups in the polymer matrix, thereby further enhancing the adhesion between the fillers and the polymer matrix. Vinyltriethoxysilane: This compound is usually used to improve the processing performance and mechanical properties of polymer materials. It can react with the active groups in the polymer matrix, thereby improving the processing performance and mechanical properties of the materials. The mixed use of the three coupling agents may produce a synergistic effect. For example, γ-(methacryloyloxy)propyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane can react with the hydroxyl groups on the surface of inorganic fillers at the same time, thereby improving the dispersibility and compatibility of the fillers. At the same time, vinyltriethoxysilane can react with the active groups in the polymer matrix, further enhancing the adhesion between the fillers and the polymer matrix. This synergistic effect may improve the comprehensive properties of the materials, including mechanical properties, thermal conductivity, high-temperature resistance, and flame retardancy. In summary, by reasonably selecting and using coupling agents, the performance of cable materials can be significantly improved, making them more suitable for use in high-temperature environments. At the same time, through material modification and composite technology, the comprehensive improvement of the cable in terms of mechanical properties, thermal conductivity, high-temperature resistance, and flame retardancy can be achieved.

[0016] Preferably, the antioxidant is bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite.

[0017] Preferably, the lubricant is one of glyceryl monostearate, zinc stearate, and calcium stearate.

[0018] Preferably, the toughening agent is a butadiene-grafted acrylate styrene copolymer.

[0019] In a second aspect, the present application provides a method for preparing a bend-resistant, heat-resistant, and flame-retardant cable, adopting the following technical solutions: As a general technical concept, the present application also provides a method for preparing the above-mentioned bend-resistant, heat-resistant, and flame-retardant cable, including the following steps: S101. Stranding 12-14 tinned copper wires with a wire diameter of 0.8-1.0 mm to obtain a copper core, coating the surface of the copper core with a low-density polyethylene film with a thickness of 0.04 mm to form an insulating layer, and stranding the copper core with the insulating layer to form a cable core; S102. Wrapping an aluminum foil with a thickness of 0.16 mm around the surface of the cable core to form a shielding layer, obtaining a semi-finished cable; S103. According to the parts by mass, put polyvinylidene fluoride, ethylene-vinyl acetate copolymer, flame retardant, thermal conductivity reinforcing filler, coupling agent, antioxidant, lubricant and toughening agent into a high-speed mixer, set the rotation speed at 300 r / min, heat up to 190 - 200 °C and mix for 20 - 30 min, and obtain the outer sheath matrix material after cooling to room temperature; S104. After melting and extruding the outer sheath matrix material at an extrusion temperature of 180 - 190 °C in a twin-screw extruder, cool and pelletize to obtain the outer sheath composite material; S105. After melting and extruding the outer sheath composite material, coat it on the surface of the semi-finished cable, and form an outer sheath layer after cooling and solidifying to obtain a bend-resistant, heat-resistant and flame-retardant cable.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. Excellent mechanical properties and toughness: By using a flame retardant prepared by mixing a modified flame retardant phosphate ester and a modified thermal conductivity flame retardant, and thermal conductivity reinforcing fillers such as modified glass fiber, modified boron nitride nanosheet, nanocellulose and graphene oxide, the outer sheath layer has good mechanical properties and toughness.

[0021] 2. Excellent thermal conductivity: The combined use of modified boron nitride nanosheet and graphene oxide, and their synergistic effect with modified glass fiber significantly enhance the thermal conductivity of the outer sheath layer.

[0022] 3. High temperature resistance: The use of modified thermal conductivity flame retardant and modified glass fiber, and the interaction between modified glass fiber and nanocellulose and graphene oxide improve the high temperature resistance of the outer sheath layer.

[0023] 4. Flame retardant performance: The use of modified flame retardant phosphate ester and modified thermal conductivity flame retardant, and their synergistic effect with thermal conductivity reinforcing filler significantly improve the flame retardant performance of the outer sheath layer.

[0024] 5. Water resistance and corrosion resistance: Pentafluorophenyl acrylate contains fluorine element and benzene ring, which improves the hydrophobic property of the outer sheath layer, thereby improving its water resistance and corrosion resistance. Specific embodiments

[0025] The implementation scheme of the present application will be described in detail below in conjunction with embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be construed as limiting the scope of the present application. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase. Toughening agent: butadiene grafted acrylate styrene copolymer, purchased from Kaneka Corporation, Japan, model: M-210; nano-cellulose solution: JK-R0757, purchased from Shanghai Jingkang Biotechnology Co., Ltd.; ethylene-vinyl acetate copolymer: industrial grade, purchased from Chongqing Ruiya Biotechnology Co., Ltd.

[0026] In the following examples and preparation examples, 1 part means 100 g.

[0027] Preparation Example 1 Preparation of Modified Flame Retardant Phosphate The preparation method of the modified flame retardant phosphate includes the following steps: S31. According to the mass parts, 238 parts of pentafluorophenyl acrylate and 120 parts of mercaptoethanol are mixed evenly, and then 4 parts of photoinitiator 1173 is added. Under ultraviolet light irradiation of 50 mW / cm 2 for 1.2 h, the product is collected to obtain a hydroxyl-containing fluorine monomer; S32. According to the mass parts, 347 parts of hexachlorocyclotriphosphazene, 1400 parts of hydroxyl-containing fluorine monomer, 560 parts of potassium carbonate, 96.6 parts of tetrabutylammonium bromide and 3000 parts of acetone are mixed. Stir for 35 min under a nitrogen atmosphere, heat up to 58 °C, and reflux for 42 h. After the reaction is completed, cool, filter to remove potassium carbonate, rotary evaporate to remove acetone, collect the product, and vacuum dry at 40 °C to obtain a flame retardant phosphate; S33. According to the mass parts, 100 parts of flame retardant phosphate and 3.3 parts of γ-(methacryloyloxy)propyltrimethoxysilane are added to 200 parts of acetone. At the same time, under nitrogen protection, heat up to 75 °C and keep warm for 2 h. Then, 0.3 part of azobisisoheptonitrile is dissolved in 10 parts of acetone to obtain an azobisisoheptonitrile solution. The azobisisoheptonitrile solution is slowly added dropwise within 1 h, and then reacted for 12 h. After that, rotary evaporate to remove acetone to obtain a modified flame retardant phosphate.

[0028] Preparation Example 2 Preparation of Modified Thermal Conductive Flame Retardant The preparation method of the modified thermal conductive flame retardant includes the following steps: S41. According to the parts by mass, 100 parts of hexachlorocyclotriphosphazene, 314 parts of p-acetaminophen, and 430 parts of potassium carbonate are added to 2500 parts of acetone and mixed evenly. Then, under nitrogen protection, the reaction is carried out at 73 °C for 50 hours. After that, the reaction mixture is poured into deionized water, stirred, filtered, and the obtained solid is washed successively with deionized water, n-hexane, and ethanol, and then placed in a vacuum drying oven and dried at 65 °C for 44 hours to obtain hexakis(4-acetamidophenoxy)cyclotriphosphazene; S42. According to the parts by mass, 51.8 parts of hexakis(4-acetamidophenoxy)cyclotriphosphazene, 500 parts of methanol, and 130 parts of an aqueous sodium hydroxide solution with a mass concentration of 43% are mixed evenly. Under a stirring rate of 100 rpm, the temperature is raised to 88 °C and the reaction is carried out for 44 hours. After the reaction mixture is cooled to room temperature, it is filtered, and the solid is washed successively with deionized water and ethanol, and then placed in a vacuum drying oven and dried at 68 °C for 48 hours to obtain hexakis(4-aminophenoxy)cyclotriphosphazene; S43. According to the parts by mass, 60 parts of hexakis(4-aminophenoxy)cyclotriphosphazene and 8.3 parts of γ-(methacryloyloxy)propyltrimethoxysilane are added to 200 parts of acetone. Meanwhile, under nitrogen protection, the temperature is heated to 77 °C and kept warm for 0.8 h. Then, 0.3 part of 2,2'-azobis(2,4-dimethylvaleronitrile) is dissolved in 10 parts of acetone to obtain a 2,2'-azobis(2,4-dimethylvaleronitrile) solution, which is slowly added dropwise within 1 h. After that, the reaction is carried out for 11 h, and then acetone is removed by rotary evaporation to obtain γ-(methacryloyloxy)propyltrimethoxysilane-modified hexakis(4-aminophenoxy)cyclotriphosphazene; S44. According to the parts by mass, nano boron nitride with a particle size of 40 - 50 nm is dried at 110 °C for 7 h. Then, 100 parts of the dried boron nitride and 100 parts of γ-(methacryloyloxy)propyltrimethoxysilane-modified hexakis(4-aminophenoxy)cyclotriphosphazene are added to 300 parts of absolute ethanol, stirred evenly, and then, under nitrogen protection, the reflux reaction is carried out at 91 °C for 11 h. After the reaction is completed, it is filtered by suction, washed with ethanol, and dried to obtain a modified thermal conductive and flame retardant.

[0029] Preparation Example 3 Preparation of Thermal Conductive and Reinforcing Filler The preparation method of the thermal conductive and reinforcing filler includes the following steps: S51. According to the parts by mass, 10 parts of chopped glass fibers with a length of 4 - 6 mm and a diameter of 10 - 15 μm are placed in 200 parts of xylene, ultrasonically dispersed for 30 min, 15 parts of glycine are added, and after reflux reaction for 12 h, it is filtered by suction, washed, and dried to obtain modified glass fibers for standby; S52. According to the parts by mass, disperse 10 parts of boron nitride nanosheets in 10 parts of an ethanol aqueous solution with a concentration of 75% and obtain a boron nitride suspension after ultrasonic dispersion. Add 10 parts of tannic acid and 0.5 part of vinyltriethoxysilane to the boron nitride suspension, mix and stir to react. After the reaction is completed, filter, wash and dry to obtain modified boron nitride nanosheets for standby; S53. According to the parts by mass, disperse 10 parts of modified glass fiber, 50 parts of modified boron nitride nanosheets and 100 parts of graphene oxide in 4000 parts of a nanocellulose solution with a mass concentration of 0.5% and ultrasonically disperse to obtain a filler mixture. Vacuum freeze-dry the filler mixture at 50 °C for 24 h to obtain a thermally conductive reinforcing filler. Example 1

[0030] Preparation of the outer sheath composite material The outer sheath layer, by parts by mass, includes the following preparation raw materials: 40 parts of polyvinylidene fluoride, 65 parts of ethylene-vinyl acetate copolymer, 15 parts of flame retardant, 30 parts of thermally conductive reinforcing filler, 1.5 parts of coupling agent, 1 part of bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, 1 part of glyceryl stearate, 2 parts of butadiene grafted acrylate styrene copolymer. Among them, the flame retardant is prepared by mixing modified flame retardant phosphate and modified thermally conductive flame retardant in a mass ratio of 4:7, and the coupling agent is prepared by mixing γ-(methacryloyloxy)propyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane and vinyltriethoxysilane in a mass ratio of 3:3:4; The preparation method of the above outer sheath composite material includes the following steps: S103. According to the parts by mass, place polyvinylidene fluoride, ethylene-vinyl acetate copolymer, flame retardant, thermally conductive reinforcing filler, coupling agent, glyceryl stearate, glyceryl stearate and butadiene grafted acrylate styrene copolymer in a high-speed mixer, set the rotation speed to 300 r / min, heat up to 190 °C and mix for 30 min, and obtain the outer sheath matrix material after cooling to room temperature; S104. After melting and extruding the outer sheath matrix material at an extrusion temperature of 180 °C in a twin-screw extruder, cool and pelletize to obtain the outer sheath composite material. Example 2

[0031] Preparation of the outer sheath composite material The outer sheath layer, by mass parts, comprises the following preparation raw materials: 45 parts of polyvinylidene fluoride, 70 parts of ethylene-vinyl acetate copolymer, 18 parts of flame retardant, 35 parts of thermally conductive reinforcing filler, 2 parts of coupling agent, 1.5 parts of bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, 1.5 parts of glyceryl stearate, 2.5 parts of butadiene-grafted acrylate styrene copolymer. Among them, the flame retardant is prepared by mixing a modified flame retardant phosphate ester and a modified thermally conductive flame retardant in a mass parts ratio of 4:9, and the coupling agent is prepared by mixing γ-(methacryloyloxy)propyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane and vinyltriethoxysilane in a mass parts ratio of 3:3:4; The preparation method of the above outer sheath composite material comprises the following steps: S103. According to the mass parts, put polyvinylidene fluoride, ethylene-vinyl acetate copolymer, flame retardant, thermally conductive reinforcing filler, coupling agent, glyceryl stearate, glyceryl stearate and butadiene-grafted acrylate styrene copolymer into a high-speed mixer, set the rotation speed at 300 r / min, heat up to 200 °C and mix for 20 min, and obtain the outer sheath matrix material after cooling to room temperature; S104. After melting and extruding the outer sheath matrix material at an extrusion temperature of 190 °C by a twin-screw extruder, cool and pelletize to obtain the outer sheath composite material. Example 3

[0032] Preparation of the outer sheath composite material The outer sheath layer, by mass parts, comprises the following preparation raw materials: 43 parts of polyvinylidene fluoride, 68 parts of ethylene-vinyl acetate copolymer, 17 parts of flame retardant, 33 parts of thermally conductive reinforcing filler, 1.7 parts of coupling agent, 1.3 parts of bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, 1.3 parts of glyceryl stearate, 2.3 parts of butadiene-grafted acrylate styrene copolymer. Among them, the flame retardant is prepared by mixing a modified flame retardant phosphate ester and a modified thermally conductive flame retardant in a mass parts ratio of 4:8, and the coupling agent is prepared by mixing γ-(methacryloyloxy)propyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane and vinyltriethoxysilane in a mass parts ratio of 3:3:4; The preparation method of the above outer sheath composite material comprises the following steps: S103. According to the mass parts, put polyvinylidene fluoride, ethylene-vinyl acetate copolymer, flame retardant, thermally conductive reinforcing filler, coupling agent, glyceryl stearate, glyceryl stearate and butadiene-grafted acrylate styrene copolymer into a high-speed mixer, set the rotation speed at 300 r / min, heat up to 195 °C and mix for 25 min, and obtain the outer sheath matrix material after cooling to room temperature; S104. After melting and extruding the outer sheath matrix material at an extrusion temperature of 185°C in a twin-screw extruder, it is cooled and pelletized to obtain the outer sheath composite material.

[0033] Comparative Example 1 Same as Example 3, except that: an equal amount of filler (prepared by mixing chopped glass fibers with a length of 4 - 6 mm and a diameter of 10 - 15 μm, boron nitride nanosheets, and graphene oxide in a mass ratio of 1:5:10) is used instead of the thermally conductive reinforcing filler.

[0034] Comparative Example 2 Same as Example 3, except that: the flame retardant is a modified flame retardant phosphate ester.

[0035] Comparative Example 3 Same as Example 3, except that: the flame retardant is a modified thermally conductive flame retardant.

[0036] Comparative Example 4 Same as Example 3, except that: the coupling agent is γ-(methacryloyloxy)propyltrimethoxysilane.

[0037] Comparative Example 5 Same as Example 3, except that: the coupling agent is 3-isocyanatopropyltriethoxysilane.

[0038] Comparative Example 6 Same as Example 3, except that: the coupling agent is vinyltriethoxysilane.

[0039] Performance detection test Samples of the outer sheath composite materials prepared in the above Examples 1 - 3 and Comparative Examples 1 - 6 are respectively taken and injection molded into test strips for the following tests, and the results are shown in Table 1.

[0040] Tensile strength, elongation at break: Tested according to the standard of GB / T1040 - 2006, and the tensile rate is 50 mm / min; Impact strength: Tested according to the standard of GB / T1843 - 2008; Thermal conductivity: Tested according to ASTM D5470; Flame retardant performance (limiting oxygen index): Tested according to the standard of GB / T2406.2 - 2009, and the limiting oxygen index of the specimen is measured by an oxygen index meter, and the sample size is 150 mm * 6.5 mm * 3 mm; Vicat softening temperature: The Vicat softening temperature of the sample is tested with reference to the standard of GB / T1633 - 2000 to judge the high-temperature resistance performance of the sample.

[0041] Table 1 Performance test

[0042] Analyzing the data in Table 1, it can be seen that: 1) The outer sheath composite materials prepared in Examples 1 - 3 have very excellent mechanical strength, toughness, thermal conductivity, high-temperature resistance, and flame retardancy. The prepared wires and cables are suitable for power transmission and signal transmission in high-temperature environments, especially in application scenarios with frequent bending and high temperature changes, such as aerospace, industrial automation equipment, automotive electronic systems, and other fields.

[0043] 2) The performance comparison and analysis of the outer sheath composite materials prepared in Example 3 and Comparative Example 1 show that the modified glass fiber, modified boron nitride nanosheets, and graphene oxide in the thermal conductivity reinforcing filler also have a synergistic effect during the melt extrusion process. On the one hand, the composite of modified boron nitride nanosheets and graphene oxide will significantly enhance the thermal conductivity of the outer sheath composite material. This is because there is a strong hydrogen bond interaction between the modified boron nitride nanosheets and graphene oxide. Under the action of hydrogen bonds, the two-dimensional boron nitride nanosheets and one-dimensional graphene oxide can be closely stacked together and highly oriented in the plane direction after melt extrusion, forming a "brick-mortar" layered structure. This highly oriented ordered in-plane arrangement will provide a good path for phonon transmission between adjacent boron nitride nanosheets, which can significantly improve the thermal conductivity of the outer sheath composite material. At the same time, the mechanical properties of the outer sheath composite material are further improved by the modified glass fiber. In addition, the modified glass fiber and modified boron nitride nanosheets can form good hydrogen bond interactions with nanocellulose, and the modified boron nitride nanosheets and modified glass fibers are relatively uniformly dispersed in graphene oxide and present an ordered layered structure, which helps to improve the mechanical properties and thermal conductivity of the outer sheath composite material.

[0044] 3) Comparative analysis of the properties of the outer sheath composite materials prepared in Example 3 and Comparative Examples 2-3 shows that the flame retardant is prepared by mixing a modified flame retardant phosphate ester and a modified thermally conductive flame retardant in a mass ratio of 4:8. The synergistic effect of the modified flame retardant phosphate ester and the modified thermally conductive flame retardant can significantly improve the flame retardant performance of the cable outer sheath composite material. The modified flame retardant phosphate ester provides a good flame retardant effect, while the modified thermally conductive flame retardant enhances the flame retardant performance through its organic-inorganic hybrid structure and the characteristics of nanomaterials. The phosphazene molecular structure in the modified thermally conductive flame retardant can remain stable at high temperatures, thereby improving the high-temperature resistance performance of the composite material. At the same time, the synergistic effect of the modified flame retardant phosphate ester and the modified thermally conductive flame retardant further enhances this high-temperature resistance performance. The synergistic effect of the modified flame retardant phosphate ester and the modified thermally conductive flame retardant can also improve the mechanical properties of the cable outer sheath composite material. The fluorine element and benzene ring structure in the modified flame retardant phosphate ester and the organic-inorganic hybrid structure in the modified thermally conductive flame retardant both contribute to improving the strength and toughness of the composite material. The combined use of modified boron nitride nanosheets and graphene oxide can significantly enhance the thermal conductivity of the cable outer sheath composite material. At the same time, the synergistic effect of the modified flame retardant phosphate ester and the modified thermally conductive flame retardant further improves this thermal conductivity performance.

[0045] 4) Comparative analysis of the properties of the outer sheath composite materials prepared in Example 3 and Comparative Examples 4-6 shows that the coupling agent is prepared by mixing γ-(methacryloyloxy)propyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, and vinyltriethoxysilane in a mass ratio of 3:3:4. Utilizing their synergistic effect can significantly improve the comprehensive performance of the outer sheath composite material, including mechanical properties, thermal conductivity, high-temperature resistance performance, and flame retardant performance.

[0046] Using the outer sheath composite materials prepared in Examples 1-3 to prepare bend-resistant, heat-resistant, and flame-retardant cables respectively, including the following steps: S101. Stranding 12 tinned copper wires with a wire diameter of 0.8 mm to obtain a copper core, coating a low-density polyethylene film with a thickness of 0.04 mm on the surface of the copper core to form an insulating layer, and stranding the copper core with the insulating layer to form a cable core; S102. Wrapping an aluminum foil with a thickness of 0.16 mm around the surface of the cable core to form a shielding layer, obtaining a semi-finished cable; S105. Melting and extruding the outer sheath composite material and coating it on the surface of the semi-finished cable, and cooling and curing to form an outer sheath layer, obtaining a bend-resistant, heat-resistant, and flame-retardant cable.

[0047] The above embodiments are only used to explain the technical solutions of the present application rather than limit them. Although the above embodiments have specifically described the present application, those skilled in the art should understand that they can still modify the specific implementation manners of the present application or make equivalent replacements. Any modification and equivalent replacement that do not depart from the spirit and scope of the present application should be covered by the protection scope of the present application.

Claims

1. A bending-resistant, heat-resistant and flame-retardant cable, characterized in that: From the inside to the outside, it includes a cable core, a shielding layer and an outer sheath layer in sequence; the cable core is made by coating a copper core with a low-density polyethylene film; the shielding layer is made by coating the cable core with aluminum foil; the outer sheath layer includes the following raw materials by weight: 40-45 parts of polyvinylidene fluoride, 65-70 parts of ethylene-vinyl acetate copolymer, 15-18 parts of flame retardant, 30-35 parts of thermal conductive reinforcing filler, 1.5-2 parts of coupling agent, 1-1.5 parts of antioxidant, 1-1.5 parts of lubricant, 2-2.5 parts of toughening agent, wherein the flame retardant is prepared by mixing modified flame retardant phosphate and modified thermal conductive flame retardant, and the thermal conductive reinforcing filler includes modified glass fiber, modified boron nitride nanosheets, nanocellulose and graphene oxide; The preparation method of the thermally conductive reinforcing filler comprises the following steps: S51, according to the mass fraction, 10 parts of chopped glass fibers with a length of 4-6 mm and a diameter of 10-15 μm were placed in 200 parts of xylene, ultrasonically dispersed for 30 min, 15 parts of glycine were added, refluxed for 12 h, filtered, washed and dried to obtain modified glass fibers for standby use; S52, dispersing 10 parts of boron nitride nanosheets in 10 parts of 75% ethanol aqueous solution by weight, obtaining a boron nitride suspension after ultrasonic dispersion, adding 10 parts of tannic acid and 0.5 parts of vinyltriethoxysilane to the boron nitride suspension, mixing and stirring to react, and after the reaction is completed, filtering, washing and drying to obtain modified boron nitride nanosheets for standby use; S53. Disperse 10 parts of modified glass fiber, 50 parts of modified boron nitride nanosheets and 100 parts of graphene oxide in 4000 parts of nanocellulose solution with a mass concentration of 0.5% and disperse them by ultrasonic to obtain a filler mixture; vacuum freeze-dry the filler mixture at 50°C for 24 hours to obtain a thermally conductive reinforcing filler.

2. A bending-resistant, heat-resistant and flame-retardant cable according to claim 1, characterized in that: The mass ratio of the modified flame retardant phosphate ester to the modified thermal conductive flame retardant is 4:7-9.

3. The bending-resistant, heat-resistant and flame-retardant cable according to claim 1, characterized in that: The preparation method of the modified flame-retardant phosphate ester comprises the following steps: S31, according to the mass fraction, 238 parts of pentafluorophenyl acrylate and 120 parts of mercaptoethanol were mixed evenly, and 4 parts of photoinitiator 1173 were added. 2 The reaction was carried out under irradiation for 1-2 hours, and the product was collected to obtain a hydroxyl fluorinated monomer; S32, according to the mass parts, 347 parts of hexachlorocyclotriphosphazene, 1400 parts of hydroxyl fluorine-containing monomer, 560 parts of potassium carbonate, 96.6 parts of tetra-n-butylammonium bromide and 3000 parts of acetone were mixed, stirred for 30-40 minutes under a nitrogen atmosphere, heated to 55-60°C, refluxed for 40-44 hours, cooled after the reaction, filtered to remove potassium carbonate, evaporated to remove acetone, collected the product, and dried in vacuo at 40°C to obtain a flame retardant phosphate; S33. According to the mass proportions, add 100 parts of flame retardant phosphate and 3.3 parts of γ-(methacryloyloxy)propyltrimethoxysilane to 200 parts of acetone, and heat to 75°C under nitrogen protection, and keep warm for 2 hours. Then, dissolve 0.3 parts of azobisisoheptanenitrile in 10 parts of acetone to obtain an azobisisoheptanenitrile solution. Slowly add the azobisisoheptanenitrile solution dropwise within 1 hour, and then react for 12 hours, then remove the acetone by rotary evaporation to obtain a modified flame retardant phosphate.

4. The bending-resistant, heat-resistant and flame-retardant cable according to claim 1, characterized in that: The preparation method of the modified thermal conductive flame retardant comprises the following steps: S41, according to the mass parts, add 100 parts of hexachlorocyclotriphosphazene, 314 parts of acetaminophenol and 430 parts of potassium carbonate to 2500 parts of acetone and mix them evenly, then react at a temperature of 70-75° C. for 48-52 hours under nitrogen protection, then pour the reacted material into deionized water, stir, filter, collect the obtained solid, wash it with deionized water, n-hexane and ethanol in turn, place it in a vacuum drying oven at a temperature of 60-70° C. and dry it for 40-48 hours to obtain hexa(4-acetylaminophenoxy)cyclotriphosphazene; S42, according to the mass fraction; 51.8 parts of hexa(4-acetylaminophenoxy)cyclotriphosphazene, 500 parts of methanol and 130 parts of 43% sodium hydroxide aqueous solution are mixed uniformly, and the mixture is heated to 85-90° C. and reacted for 40-48 hours at a stirring rate of 100 rpm, and the reacted material is cooled to room temperature, filtered, and the solid is washed with deionized water and ethanol in turn, and then placed in a vacuum drying oven at a temperature of 68° C. and dried for 48 hours to obtain hexa(4-aminophenoxy)cyclotriphosphazene; S43, according to the mass parts, add 60 parts of hexa(4-aminophenoxy)cyclotriphosphazene and 8.3 parts of γ-(methacryloyloxy)propyltrimethoxysilane to 200 parts of acetone, and heat to 75-80°C under nitrogen protection, and keep warm for 0.7-1h, then dissolve 0.3 parts of azobisisoheptanenitrile in 10 parts of acetone to obtain an azobisisoheptanenitrile solution, slowly add the azobisisoheptanenitrile solution dropwise within 1h, and then react for 10-12h, and then remove the acetone by rotary evaporation to obtain γ-(methacryloyloxy)propyltrimethoxysilane modified hexa(4-aminophenoxy)cyclotriphosphazene; S44. Dry the nano boron nitride with a particle size of 40-50 nanometers at 100-120°C for 6-8 hours according to the mass fraction, then add 100 parts of the dried boron nitride and 100 parts of γ-(methacryloyloxy)propyltrimethoxysilane-modified hexa(4-aminophenoxy)cyclotriphosphazene to 300 parts of anhydrous ethanol, stir evenly, and reflux at 88-92°C for 10-12 hours under nitrogen protection. After the reaction is completed, filter, wash with ethanol, and dry to obtain a modified thermal conductive flame retardant.

5. The bending-resistant, heat-resistant and flame-retardant cable according to claim 1, characterized in that: The coupling agent is prepared by mixing γ-(methacryloyloxy)propyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane and vinyltriethoxysilane in a mass ratio of 3:3:

4.

6. The bending-resistant, heat-resistant and flame-retardant cable according to claim 1, characterized in that: The antioxidant is bis(2,4-dicumylphenyl)pentaerythritol diphosphite.

7. The bending-resistant, heat-resistant and flame-retardant cable according to claim 1, characterized in that: The lubricant is one of glyceryl stearate, zinc stearate and calcium stearate.

8. The bending-resistant, heat-resistant and flame-retardant cable according to claim 1, characterized in that: The toughening agent is butadiene grafted acrylate styrene copolymer.

9. A method for preparing a bending-resistant, heat-resistant and flame-retardant cable according to any one of claims 1 to 8, characterized in that: The following steps are involved: S101, preparing a cable core: twisting 12-14 tinned copper wires with a wire diameter of 0.8-1.0 mm to obtain a copper core, coating the surface of the copper core with a low-density polyethylene film with a thickness of 0.04 mm to form an insulating layer, and twisting the copper core with the insulating layer to form a cable core; S102, preparing a shielding layer: wrapping an aluminum foil with a thickness of 0.16 mm around the surface of the cable core to form a shielding layer, and obtaining a semi-finished cable; S103, preparing an outer sheath composite material: according to the mass fractions, polyvinylidene fluoride, ethylene-vinyl acetate copolymer, flame retardant, thermal conductive reinforcing filler, coupling agent, antioxidant, lubricant and toughening agent are placed in a high-speed mixer, the speed is set to 300r / min, the temperature is raised to 190-200°C and mixed for 20-30min, and the outer sheath matrix material is obtained after cooling to room temperature; then the outer sheath matrix material is melt-extruded at an extrusion temperature of 180-190°C in a twin-screw extruder, and then cooled and granulated to obtain an outer sheath composite material; S104, preparing a flame-retardant cable: melt-extrude the outer sheath composite material and coat it on the surface of the semi-finished cable, and form an outer sheath layer after cooling and solidification to obtain a bending-resistant, heat-resistant and flame-retardant cable.

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