Low-dielectric high-flame-retardance polyphenyl ether composite cable material and preparation method thereof

Abstract

The invention discloses a low-dielectric high-flame-retardancy polyphenyl ether composite cable material and a preparation method thereof, and the raw materials comprise the following components by mass: 40%-50% of polyphenyl ether, 15%-20% of a hydrogenated styrene-butadiene block copolymer, 7%-11% of polydopamine surface modified hexagonal boron nitride, 10%-15% of ammonium polyphosphate, 5.5%-7% of melamine, 2%-4% of bismaleimide functionalized phosphorus-containing polyaryletherketone, and 3%-4% of a compatilizer. 0.7%-1.5% of an antioxidant, 1%-2% of polyethylene wax and 0-3.5% of processing oil. According to the invention, a quaternary synergistic system of bismaleimide functionalized phosphorus-containing polyaryletherketone, modified h-BN + intumescent flame retardant and EVA-g-MAH is constructed, the flame retardant efficiency is improved, low dielectric constant and low dielectric loss are realized, good processability under extremely low oil quantity is realized, and the problem of oil precipitation is fundamentally avoided.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polymer cable materials, and particularly relates to a low-dielectric high-flame-retardant polyphenyl ether composite cable material suitable for 5G communication, high-voltage charging of new energy vehicles and the like, and a preparation method thereof. BACKGROUND

[0002] As a core component of modern power transmission and communication systems, the importance of cables is self-evident. With its excellent electrical conductivity, stable transmission quality and flexible laying mode, cables have been widely used in various fields. In the field of communication, cables serve as the medium for information transmission, enabling long-distance and high-capacity data transmission, greatly promoting the development of information technology. Whether it is traditional telephone communication or modern Internet services, cables are the basis for realizing these functions. Especially with the popularization of new generation communication technologies such as 5G, the demand for high-speed data transmission is increasing, and the quality and technical level of cables are directly related to the stability and efficiency of the communication system.

[0003] Traditional cable materials usually use rubber or PVC as the base material, which is easy to burn under the action of fire and release toxic and harmful gases, posing a threat to human health and environmental safety. There are many types of thermoplastic elastomers, mainly including styrene-based (TPS), olefin-based (TPO), cross-linked olefin-based (TPV), chlorovinyl-based (TPVC), polyurethane-based (TPU) and the like, which have high elasticity, high strength, low density, easy processing and other characteristics, and also have good insulation, high and low temperature resistance, fatigue resistance, good hand feeling, no odor, and have become the first choice material for replacing PVC in the field of electronic cables.

[0004] Polyphenyl ether (chemical name: poly 2,6-dimethyl-1,4-phenyl ether, abbreviated as PPO) has outstanding electrical insulation, low dielectric constant and excellent water resistance, good wear resistance, mechanical strength and dimensional stability, its dielectric performance ranks first among plastics, and it has self-flame retardance (oxygen index can reach 29) and self-extinguishing property, and becomes an ideal base material for high-end cable materials, and is widely researched and applied in the field of electrical insulation materials.

[0005] However, in order to meet the extreme requirements of modern electronic and electrical equipment on heat dissipation, signal integrity and safety, PPO-based cable materials face multiple challenges: (1) Conflict between thermal conductivity and dielectricity: introducing nano fillers (such as graphene, ceramic powder) and surface modifiers (such as silane coupling agent) to enhance dispersion, compatibility and functional performance (such as heat resistance, dielectricity). However, high thermal conductivity fillers (such as hexagonal boron nitride, h-BN) are prone to agglomeration, increase dielectric loss, and have large interfacial thermal resistance with polymer matrix.

[0006] (2) The contradiction between flame retardancy and mechanics: The use of phosphorus and nitrogen-based flame retardants (such as resorcinol bis(diphenyl phosphate), polyphosphate, etc.), metal hydroxides (such as magnesium hydroxide, aluminum hydroxide) and compound systems can improve flame retardancy efficiency and reduce environmental impact. However, the addition of large amounts of halogen-free flame retardants (such as ammonium polyphosphate APP / melamine MEL) will seriously damage the mechanical properties of the material, especially the strength retention rate at high temperatures.

[0007] (3) The contradiction between processability and performance stability: PPO can be blended with various polymers (such as SEBS, polyolefin elastomers, nitrile rubber, etc.) to improve flexibility, oil resistance and mechanical strength. However, the main disadvantage of polyphenylene ether is its poor melt flowability and difficulty in processing and molding. In order to improve the processing flowability of the PPO / SEBS system, a large amount of processing oil is often added, which leads to oil precipitation, flame retardant dilution and long-term reliability decline.

[0008] Existing technologies mostly focus on improving single properties or employ simple physical blending, making it difficult to systematically solve the aforementioned synergistic challenges. Therefore, there is an urgent need for an innovative molecular design and composite material system to fundamentally reconcile these contradictions.

[0009] Patent document CN113861658A discloses a scratch-resistant, halogen-free, flame-retardant elastomer, the raw materials of which include: 10-30 parts of polyphenylene ether resin; 10-40 parts of hydrogenated styrene-butadiene block copolymer; 10-30 parts of polypropylene resin; 5-15 parts of polyolefin elastomer; 10-40 parts of filler oil; 5-15 parts of polyamide elastomer; 10-25 parts of composite scratch-resistant agent; and 15-40 parts of flame retardant. The composite scratch-resistant agent is a compound of silicone powder, maleic anhydride-grafted SEBS, and erucamide; the flame retardant is prepared by compounding melamine cyanurate and aluminum hypophosphite in a mass ratio of 2:3; the filler oil is paraffin-based white oil and / or naphthenic white oil; and the polyolefin elastomer is ethylene-propylene copolymer and / or ethylene-octene copolymer. However, the literature added a large amount of white oil, which not only easily precipitates out, causing a decline in material performance or poor appearance, but also reduces the flame retardancy of the material; in addition, the flame retardancy and fire resistance of the material still do not meet the requirements.

[0010] Patent document CN119529504A discloses a modified ceramicized flame-retardant polyphenylene ether insulated wire and cable material, which is made from the following raw materials in the indicated mass fractions: 15%–20% polyphenylene ether resin, 10%–20% SEBS thermoplastic elastomer, 4%–8% polypropylene resin, 3%–8% maleic anhydride grafting material, 5%–20% melamine cyanurate, 5%–15% aluminum diethyl phosphite, 1%–4% 2,3-dimethyl-2,3-diphenylbutane, 10%–30% compound ceramic powder, and 1%–4% antioxidant; the compound ceramic powder is a mixture of any three of glass powder, montmorillonite, nano alumina, nano magnesium oxide, ammonium polyphosphate, wollastonite, and sepiolite; melamine cyanurate, aluminum diethyl phosphite, and 2,3-dimethyl-2,3-diphenylbutane are flame retardants. However, in order to achieve the fire-resistant properties of "ceramization", this paper uses compound ceramic powder to increase the electrical insulation and water resistance of the cable, but at the same time it will reduce the toughness of the cable, sacrifice the mechanical and dielectric properties of the material, and it does not have thermal conductivity.

[0011] Patent document CN120590696A discloses a low-smoke halogen-free flame-retardant cable material and its preparation method. The low-smoke halogen-free flame-retardant cable material includes: 100 parts of polyolefin blend resin, 10-20 parts of polyphenylene ether, 3-8 parts of glycidyl methacrylate grafted POE, 1-3 parts of hyperbranched polyesteramide, 50-80 parts of flame retardant, 5-15 parts of silicone powder, 0.5-1.5 parts of antioxidant, and 0.05-0.2 parts of organozirconium compound. The flame retardant includes magnesium hydroxide, aluminum hydroxide, and phosphorus-nitrogen intumescent flame retardant in a weight ratio of (14-18):(7-9):1. However, the flame retardants in this literature are mainly magnesium hydroxide, aluminum hydroxide and a small amount of phosphorus and nitrogen. The high filler content (50-80 parts) leads to a decrease in mechanical properties and difficulty in processing. Flame retardancy is obtained at the expense of overall performance. Moreover, traditional hydroxides have poor thermal conductivity and do not take thermal conductivity and high-frequency electrical properties into consideration. They are not suitable for scenarios that require heat dissipation and cannot meet the stringent requirements of cable materials in emerging fields such as 5G and EV. Summary of the Invention

[0012] This invention provides a low-dielectric, high-flame-retardant polyphenylene ether composite cable material and its preparation method suitable for scenarios such as 5G communication and high-voltage charging of new energy vehicles. It simultaneously optimizes the filler-matrix interface, flame-retardant synergistic network, and melt processing behavior, so that it has high thermal conductivity, low dielectric loss, high flame retardancy, and excellent processing stability, thereby comprehensively solving the above-mentioned technical problems.

[0013] To achieve the above objectives, the technical solution of the present invention is as follows: This invention discloses a low-dielectric, high-flame-retardant polyphenylene ether composite cable material, comprising the following components by mass fraction: 40%–50% polyphenylene ether, 15%–20% hydrogenated styrene-butadiene block copolymer, 7%–11% polydopamine-modified hexagonal boron nitride (PDA@h-BN), 10%–15% ammonium polyphosphate, 5.5%–7% melamine, 2%–4% bismaleimide-functionalized phosphorus-containing polyarylether ketone (BMI-P-PAEK), 3%–4% compatibilizer, 0.7%–1.5% antioxidant, 1%–2% polyethylene wax, and 0%–3.5% processing oil; The compatibilizer is maleic anhydride-grafted vinyl acetate, with a VA content of 23%–27% and a maleic anhydride grafting rate of 0.8%–1.2%; the bismaleimide-functionalized phosphorus-containing polyarylether ketone has a number average molecular weight of 5000–15000 g / mol, wherein the mass content of phosphorus (P) is 1.0%–2.2%, and the content of bismaleimide groups is 0.15–0.45 mmol / g.

[0014] Preferably, in the bismaleimide-functionalized phosphorus-containing polyarylether ketone, the mass content of phosphorus is 1.2% to 1.8%, and the content of bismaleimide groups is 0.25 to 0.35 mmol / g.

[0015] The preparation method of the bismaleimide-functionalized phosphorus-containing polyarylether ketone includes the following steps: D1, terminal amino polyether ketone or terminal amino polyether ketone, phosphorus-containing monomer DOPO-HQ and 4,4'-difluorobenzophenone (DFBP) are mixed in a designed ratio in N-methylpyrrolidone (NMP) solvent with anhydrous potassium carbonate as catalyst, and subjected to solution polycondensation reaction at 180-190℃ for 8-12h; after the reaction, precipitation, washing and drying are performed to obtain P-PAEK powder; D2, P-PAEK is dissolved in N,N-dimethylacetamide, excess 4-maleimide benzoic acid is added, and the reaction is carried out at room temperature for 24-48h under the action of a catalyst. After precipitation, thorough washing and drying of the reaction solution, the final product BMI-P-PAEK powder (light yellow) is obtained.

[0016] The number-average molecular weight (Mn) of the amino-terminated polyether ketone (Amine-PEK) or amino-terminated polyether ether ketone (Amine-PEEK) is 5000–15000 g / mol, and the amino content is ≥0.95 mmol / g. Its preparation methods include hydrolysis, leaving group removal, and catalytic ammonia modification. A preferred method is to first synthesize fluorine-terminated polyether ether ketones from 4,4'-difluorobenzophenone and hydroquinone, and then modify the terminal groups with 4-aminophenol to convert them into amino-terminated polyether ether ketones. The phosphorus-containing monomer DOPO-HQ is 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, CAS number 99208-50-1, and is an adduct of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) with p-benzoquinone, and it itself contains two phenolic hydroxyl groups.

[0017] Preferably, the molar ratio of the terminal amino polyether ketone or terminal amino polyether ketone and 4,4'-difluorobenzophenone (DFBP) is 1:1; the amount of phosphorus-containing monomer DOPO-HQ added is determined based on the target phosphorus content of 1.0% to 2.2%; and the amount of 4-maleimide benzoic acid added is 1.2 to 1.5 times the molar number of the terminal amino group of P-PAEK.

[0018] The compatibilizer of this invention must be maleic anhydride-grafted ethylene-vinyl acetate (VA content 23%–27%). Not only do its anhydride groups react with the amino groups of PDA to form interfacial chemical bonds, acting as a "molecular bridge" to enhance the bonding force between h-BN and the matrix, but its molecular chains can also entangle with the matrix, further improving the interfacial strength between PDA@h-BN and the resin. For example, Arkema's Orevac T9304.

[0019] Preferably, the polydopamine-modified hexagonal boron nitride (PDA@h-BN) is prepared by in-situ polymerization of polydopamine (PDA) onto the surface of hexagonal boron nitride (h-BN). The hexagonal boron nitride has a particle size of 8–15 μm and a purity ≥99.5%, wherein the loading of polydopamine is 3%–5% of the mass of hexagonal boron nitride. The introduction of PDA@h-BN in this invention significantly improves the dispersibility of h-BN in the polymer matrix, avoids agglomeration, and enhances the interfacial compatibility and interfacial bonding force between h-BN and the PPO / SEBS matrix. This is crucial for achieving high thermal conductivity while maintaining mechanical properties.

[0020] Preferably, the preparation method of the polydopamine-modified hexagonal boron nitride (PDA@h-BN) is as follows: D1, dispersing hexagonal boron nitride (h-BN) powder in Tris-HCl buffer solution with pH 8.0–9.0; D2, adding dopamine hydrochloride (CAS: 62-31-7, the amount added is 3%–5% of the mass of h-BN), and stirring the reaction at room temperature for 20–30 h; D3, collecting the solid by centrifugation, washing with deionized water, vacuum drying at 50–65 °C, grinding, and passing through a 200-mesh sieve to obtain PDA@h-BN powder. Preferably, the mass concentration of the hexagonal boron nitride in the Tris-HCl buffer solution is 5–10 mg / mL.

[0021] Preferably, the polyphenylene ether (CAS: 24938-67-8) is a hydroxyl-terminated polyphenylene ether resin with a melt index of 10-18 g / 10 min and an intrinsic viscosity (IV) of 0.35-0.42 dL / g (measured in chloroform at 25°C); for example, LXR035 and LXR040 produced by Shanxi Lanxing, with a glass transition temperature (Tg) ≥210°C; polyphenylene ether provides excellent electrical insulation, low dielectric constant / loss, and high heat distortion temperature for composite cable materials.

[0022] Preferably, the hydrogenated styrene-butadiene block copolymer is a linear styrene block copolymer with a melt flow rate of 20-25 g / 10 min at 230°C / 5 kg and a viscosity of 800-1200 mPa·s for the 25% toluene solution; wherein the styrene content is 20%-32% by mass, for example, Kraton's SEBS G1652 and G1642; SEBS is used as a toughening agent to improve the brittleness and processing flowability of PPO to ensure good extrusion processability of the blend.

[0023] Preferably, the ammonium polyphosphate has a degree of polymerization n > 1000, a water solubility of < 0.5% at room temperature for 2 hours, and a particle size D50 of 10–20 μm, for example, Clariant Exolit AP 435; the melamine has a purity > 99.5% and a D50 particle size of 4–10 μm; more preferably, the mass ratio of the ammonium polyphosphate to the melamine is (1.5–2.5):1; the ammonium polyphosphate and melamine constitute a highly efficient halogen-free intumescent flame retardant system, which synergistically forms a dense foamed char layer with the char-forming tendency of PPO during combustion; this halogen-free flame retardant is compounded with PDA@h-BN, and the h-BN sheets can strengthen the char layer structure.

[0024] Preferably, the antioxidant is at least one of antioxidant 1076, antioxidant 168, antioxidant 1010, antioxidant 1035 and antioxidant 1024, more preferably a compound of antioxidant 1076 and antioxidant 168 in a mass ratio of 1:1, providing protection against processing and long-term thermo-oxidative aging, especially for the stability of PPO under high-temperature processing.

[0025] Preferably, the polyethylene wax has a molecular weight of 3000-5000, a dropping point of 100-110℃, and an acid value of <1mg KOH / g, such as Honeywell AC 6A, Ceralene 2T, and Clariant PE520, and is used as a lubricant to assist in processing.

[0026] The processing oil is a naphthenic oil or paraffin oil with a kinematic viscosity of 90-110 cSt at 40°C and a pour point of <-30°C, for example: Nyflex 222B.

[0027] The low dielectric and high flame retardant polyphenylene ether composite cable material of the present invention has a dielectric constant ≤2.26, dielectric loss ≤0.0028, thermal diffusivity ≥0.85W / (m·K), limiting oxygen index ≥39% at 1MHz, and still has processability when the processing oil content is ≤3.5%.

[0028] The present invention discloses a method for preparing a low-dielectric, high-flame-retardant polyphenylene ether composite cable material, comprising the following steps: S1, the polydopamine surface-modified hexagonal boron nitride, a compatibilizer, and 20%–50% hydrogenated styrene-butadiene block copolymer are melt-blended in a twin-screw extruder, granulated, and made into a thermally conductive masterbatch; the melt extrusion temperature is 160–200°C, the screw speed is 250–300 rpm, and the vacuum degree is -0.070–-0.080 MPa; S2, polyphenylene ether, residual hydrogenated styrene-butadiene block copolymer, thermally conductive masterbatch, bismaleimide-functionalized phosphorus-containing polyarylether ketone, antioxidant, polyethylene wax, and processing oil are thoroughly mixed and fed into the main feed, while ammonium polyphosphate and melamine are fed into the side feed. The mixture is melt-blended using a co-rotating twin-screw extruder. The melt extrusion temperature is 180–250°C, the screw speed is 250–350 rpm, and the vacuum degree is -0.075–-0.085 MPa. After melt extrusion, the mixture is cooled and pelletized to obtain the composite cable material.

[0029] Compared with the prior art, the positive effects of the present invention are: This invention creatively employs "bismaleimide-functionalized phosphorus-containing polyarylether ketone (BMI-P-PAEK)" as a reactive synergistic framework agent to construct a quaternary synergistic system of "bismaleimide-functionalized phosphorus-containing polyarylether ketone + polydopamine-modified hexagonal boron nitride + intumescent flame retardant + compatibilizer EVA-g-MAH": polydopamine-modified hexagonal boron nitride enhances the interfacial compatibility and interfacial bonding force between h-BN and the PPO / SEBS matrix; BMI-P-PAEK acts as a "molecular bridge" and reacts with the active groups on the surface of polydopamine-modified h-BN (PDA@h-BN) to form... The strongly chemically bonded interface layer, with PAEK segments forming physical entanglement / compatibility with the PPO / SEBS matrix, achieves a high thermal conductivity (≥0.85W / m·K) with a relatively low filler content. This not only rapidly conducts heat generated inside the cable to the external environment, preventing heat accumulation and ensuring long-term stable operation of the cable at high temperatures and high frequencies, but also maintains the material's good flexibility and processability. This meets the requirements of cutting-edge applications with extreme heat dissipation and signal integrity requirements, such as internal cables of 5G / 6G communication base stations, high-speed data transmission lines, and high-current charging pile cables for electric vehicles.

[0030] This invention selects low-viscosity SEBS, introduces PDA@h-BN with lubricating properties and polyethylene wax, and achieves good processability under conditions of extremely low oil content (3%) or even no processing oil, fundamentally avoiding the problem of oil separation and ensuring flame retardant efficiency. Detailed Implementation

[0031] Those skilled in the art should recognize that this embodiment is only used to illustrate the present invention and is not intended to limit the present invention. Any changes or modifications to the embodiment within the scope of the present invention are within the scope of the claims of the present invention.

[0032] The preparation method of bismaleimide-functionalized phosphorus-containing polyarylether ketones in Examples 1-6 includes the following steps: D1. Acid-terminated polyetherketone (Mn=10000, customized by Jilin University, 100 parts by weight as a baseline), phosphorus-containing monomer DOPO-HQ (10-15 parts by weight, calculated based on a target phosphorus content of 1.0%-2.0%), and 4,4'-difluorobenzophenone (DFBP, molar ratio to DOPO-HQ 1:1) were mixed in N-methylpyrrolidone (NMP) solvent with anhydrous potassium carbonate as a catalyst (1.05-1.10 times the molar amount of the phenolic hydroxyl groups). Under nitrogen protection, the mixture was heated to 145°C for azeotropic desulfurization. Water was added for 3 hours to remove water from the system; after removing toluene, the temperature was slowly raised to 180-190℃ for solution polycondensation reaction for 10 hours; after the reaction, the viscous reaction solution was cooled to room temperature and added dropwise to an excess ethanol / water mixture (volume ratio 1:1) under vigorous stirring, and the product precipitated as fibrous or powdery precipitate; the precipitate was filtered and repeatedly washed with hot water and ethanol to remove inorganic salts and solvents; the product was vacuum dried at 120℃ for 24 hours to obtain a pale yellow phosphorus-containing polyaryletherketone (P-PAEK) powder; the actual phosphorus content was determined by elemental analysis.

[0033] D2. P-PAEK was dissolved in anhydrous N,N-dimethylacetamide (DMAc) to prepare a solution of approximately 10%. 4-maleimide benzoic acid was added at 1.2–1.5 times the molar amount of the terminal amino group of P-PAEK, along with the catalyst DMAP (4-dimethylaminopyridine, in an amount 0.15 times the molar amount of the carboxyl group) and the condensing agent EDC·HCl (1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, in an amount 1.2 times the molar amount of the carboxyl group). The reaction was carried out at room temperature (25°C) for 35 h. The reaction solution was added dropwise to excess deionized water to precipitate the product. The precipitate was filtered and washed thoroughly successively with dilute hydrochloric acid aqueous solution (to remove residual DMAP), sodium bicarbonate aqueous solution (to neutralize excess acid), water, and ethanol. The final product was vacuum dried at 80°C for 48 h to obtain a light yellow BMI-P-PAEK powder.

[0034] According to the test results, the phosphorus content in the bismaleimide-functionalized phosphorus-containing polyarylether ketone used in Examples 1 to 5 is about 1.42%, and the content of bismaleimide groups is about 0.31 mmol / g.

[0035] Examples 1-6 and Comparative Examples 1-4 The raw material components of the low-dielectric, high-flame-retardant polyphenylene ether composite cable materials of Examples 1-6 and Comparative Examples 1-4 are listed in Table 1. The preparation method includes the following steps: S1, polydopamine surface-modified hexagonal boron nitride, compatibilizer (MAH-g-EVA, Arkema Orevac T9304), and 50% hydrogenated styrene-butadiene block copolymer (Kertene SEBS G1652) are melt-blended and granulated in a co-rotating twin-screw extruder (L / D ratio ≥ 40:1) to produce a thermally conductive masterbatch. The melt extrusion process parameters are: zone 1 160℃, zone 2 175℃, zone 3 185℃, zone 4 195℃, zone 5 200℃, zone 6 200℃, die head 195℃, screw speed 250rpm; vacuum exhaust is turned on in zone 5, vacuum degree -0.07MPa.

[0036] S2, polyphenylene ether (Shanxi Lanxing LXR040), remaining SEBS, thermally conductive masterbatch, BMI-P-PAEK powder, antioxidants (antioxidant 1076 and antioxidant 168 compounded at a mass ratio of 1:1), polyethylene wax (Ceralene 2T, molecular weight 5000), and processing oil (naphthenic oil, Nyflex 222B) are thoroughly mixed and fed into the main feed. Ammonium polyphosphate (Clariant Exolit AP435) and melamine are mixed and fed into the third zone side feed port of the twin-screw extruder. A co-rotating twin-screw extruder (L / D ratio ≥ 40:1) is used for melt blending and granulation. The melt extrusion temperatures are: Zone 1 180℃, Zone 2 210℃, Zone 3 230℃, Zone 4 250℃, Zone 5 255℃, Zone 6 250℃, Zone 7 240℃, and die head 235℃; screw speed 300 rpm. At rpm, a dual-stage vacuum exhaust system is set in zones 5 and 7, with a vacuum degree of -0.08MPa. After melt extrusion, the material is cooled and pelletized to obtain the final cable material.

[0037] The preparation method of polydopamine-modified hexagonal boron nitride is as follows: D1, 100g of hexagonal boron nitride (h-BN, particle size 8-12μm) powder is dispersed in 1L of Tris-HCl buffer (pH 8.5, concentration 10mmol / L), and dispersed at 5000rpm for 30min using a high-shear dispersant emulsifier to form a uniform suspension; D2, 4.0g of dopamine hydrochloride (4% of the mass of h-BN) is added, and the mixture is reacted with continuous mechanical stirring (300rpm) at room temperature in the dark for 24h; D3, the solid is collected by centrifugation, washed with deionized water, and vacuum dried at 60℃ for 12h; the dried PDA@h-BN block is lightly ground and passed through a 200-mesh sieve to obtain PDA@h-BN powder. The polydopamine loading in the obtained PDA@h-BN is 3.97% of the mass of hexagonal boron nitride.

[0038] Table 1. Raw material composition of Examples 1-6 and Comparative Examples 1-4, in %wt. Comparative Examples 1-4 are comparative examples of Example 3, with the following differences: Comparative Example 1 does not add BMI-P-PAEK; Comparative Example 2 does not add BMI-P-PAEK, but directly uses ordinary amino-terminated polyetherketone (Mn=10,000); Comparative Example 3 does not add PDA@h-BN, but increases the amount of ammonium polyphosphate and melamine by equal weight; Comparative Example 4 does not add BMI-P-PAEK and PDA@h-BN, but increases the amount of ammonium polyphosphate and melamine by equal weight.

[0039] Test Experiment Example The composite cable materials of Examples 1-6 and Comparative Examples 1-4 were tested as follows: thermal diffusivity (thermal conductivity) was determined according to ASTM E1461-2013; vertical burning (1.6 mm) flame retardancy was tested according to UL 94; limiting oxygen index was determined according to ASTM D2863-2017a; dielectric constant and dielectric loss were determined according to ASTM D150-2018; tensile strength and elongation at break were determined according to ASTM D638-2003; heat distortion temperature at 1.82 MPa was determined according to ASTM D648; and the volume change rate was measured by immersion in IRM903 oil at 70°C for 120 h according to ASTM D471-2006, which is the oil resistance.

[0040] Table 2 Performance of passivation films in Examples 1-6 and Comparative Examples 1-4 As shown in Table 2, this invention creatively employs "bismaleimide-functionalized phosphorus-containing polyarylether ketone (BMI-P-PAEK)" as a reactive synergistic framework agent to construct a quaternary synergistic system of "bismaleimide-functionalized phosphorus-containing polyarylether ketone + polydopamine-modified hexagonal boron nitride + intumescent flame retardant + compatibilizer EVA-g-MAH". This synergistic effect can simultaneously optimize the filler-matrix interface, flame retardant synergistic network, and melt processing behavior, greatly improving the flame retardant efficiency (LOI≥38%), while simultaneously achieving low dielectric constant (≤2.26) and low dielectric loss (≤0.0028).

[0041] This is because: (1) The bismaleimide (BMI) active groups grafted to the molecular chain ends of BMI-P-PAEK react with the active groups on the surface of polydopamine-modified h-BN (PDA@h-BN) at the processing temperature to form a strongly chemically bonded interface layer. The PAEK segments then form physical entanglement / compatibility with the PPO / SEBS matrix, constructing an efficient and stable heat conduction pathway from the filler to the matrix, providing excellent compatibility and high thermal stability. (2) The PAEK skeleton itself is a high-performance engineering plastic, which improves the high-temperature strength and modulus of the system. The phosphorus-containing structural units (such as DOPO derivatives) embedded in its molecular chain serve as an efficient acid source, generating a "gas-solid" synergistic flame retardant effect with the main flame retardant system (APP / MEL) during combustion, promoting the formation of a denser and stronger expanded char layer, and achieving the effect of "strengthening the char layer". (3) BMI-P-PAEK improves melt strength, and its interfacial bonding with PDA@h-BN forms a weak cross-linked network, which significantly reduces the system's dependence on processing oil. Stable extrusion can be achieved at extremely low oil content (0-3.5%), completely avoiding oil precipitation. (4) PDA@h-BN has excellent thermal conductivity, providing a heat conduction path and directly improving the thermal diffusivity of the material. Moreover, it synergistically enhances the high Tg of PPO itself, improving the thermomechanical properties of the material. When burning, h-BN can promote the formation of a denser and stronger char layer. In synergy with the gasbag of the intumescent flame retardant (ammonium polyphosphate / melamine compound system), it greatly improves the flame retardant efficiency (LOI≥39%). Thanks to the excellent dispersion and interfacial bonding of PDA@h-BN, its hard lamellar structure can effectively restrict the movement of polymer molecular chains at high temperatures, thereby significantly improving the material's resistance to deformation under load. PDA modification improves the interfacial density, and the dense interfacial layer effectively hinders the path of oil molecules to penetrate into the material. The h-BN sheets also provide a barrier effect. The well-dispersed nanosheets form tortuous paths in the composite material, which greatly delays the diffusion and swelling of oil molecules.

[0042] Compared to the absence of BMI-P-PAEK (Comparative Example 1) and the addition of ordinary PAEK (Comparative Example 1), the dielectric constant and loss of Examples 1-6 all decreased. This demonstrates that the introduction of BMI-P-PAEK not only did not impair insulation due to the increase in functional groups, but also reduced signal transmission loss at 1MHz by optimizing filler dispersion and reducing interface defects, which is crucial for 5G / 6G high-frequency communication cables.

[0043] Compared with Example 3, Comparative Example 3 did not add PDA@h-BN, and Comparative Example 4 did not add BMI-P-PAEK and PDA@h-BN, but added APP / MEL. Due to the complete removal of the thermally conductive filler h-BN, the thermal conductivity of the material decreased significantly, with the thermal conductivity falling back to the level of the base polymer (approximately 0.25 W / m·K), resulting in a loss of active heat dissipation capability. Although the total amount of flame retardant increased, the reinforcing and densifying effect of h-BN sheets on the char layer (the "brick wall" effect) was lost, causing the flame retardant rating to drop from V-0 to V-1, and the oxygen index also decreased. This demonstrates the synergistic reinforcing effect of h-BN in the flame retardant system, rather than a simple physical filler. The addition of a large amount of inorganic flame retardant disrupted the continuity of the polymer matrix, leading to a slight deterioration in electrical and mechanical properties. Oil resistance mainly relies on the chemical resistance of the polymer matrix (PPO / SEBS) itself, but due to the higher total amount of flame retardant, the weak interface between the inorganic filler and the matrix may become a weak point for oil molecule penetration, resulting in a swelling rate slightly higher than in the example.

Claims

1. A low-dielectric, high-flame-retardant polyphenylene ether composite cable material, characterized in that, The raw materials include the following components by mass fraction: 40%–50% polyphenylene ether, 15%–20% hydrogenated styrene-butadiene block copolymer, 7%–11% polydopamine-modified hexagonal boron nitride, 10%–15% ammonium polyphosphate, 5.5%–7% melamine, 2%–4% bismaleimide-functionalized phosphorus-containing polyarylether ketone, 3%–4% compatibilizer, 0.7%–1.5% antioxidant, 1%–2% polyethylene wax, and 0–3.5% processing oil; the compatibilizer is maleic anhydride-grafted vinyl acetate, with a VA content of 23%–27% and a maleic anhydride grafting rate of 0.8%–1.2%; the bismaleimide-functionalized phosphorus-containing polyarylether ketone has a number average molecular weight of 5000–15000 g / mol, wherein the mass content of phosphorus is 1.0%–2.2%, and the content of bismaleimide groups is 0.15–0.45 mmol / g.

2. The low-dielectric, high-flame-retardant polyphenylene ether composite cable material according to claim 1, characterized in that, In the bismaleimide-functionalized phosphorus-containing polyarylether ketone, the mass content of phosphorus element is 1.2% to 1.8%, and the content of bismaleimide groups is 0.25 to 0.35 mmol / g; the polydopamine-modified hexagonal boron nitride is prepared by in-situ polymerization of polydopamine on the surface of hexagonal boron nitride, the particle size of hexagonal boron nitride is 8 to 15 μm, the purity is ≥99.5%, and the loading of polydopamine is 3% to 5% of the mass of hexagonal boron nitride.

3. The low-dielectric, high-flame-retardant polyphenylene ether composite cable material according to claim 1, characterized in that, The preparation method of the bismaleimide-functionalized phosphorus-containing polyarylether ketone includes the following steps: D1, terminal amino polyether ketone or terminal amino polyether ketone, phosphorus-containing monomer DOPO-HQ and 4,4'-difluorobenzophenone are mixed in a designed ratio in N-methylpyrrolidone solvent with anhydrous potassium carbonate as catalyst, and subjected to solution polycondensation reaction at 180-190℃ for 8-12h; after the reaction, precipitation, washing and drying are performed to obtain P-PAEK powder; D2, P-PAEK powder is dissolved in N,N-dimethylacetamide, excess 4-maleimide benzoic acid is added, and the reaction is carried out at room temperature for 24-48h under the action of a catalyst. After precipitation, thorough washing and drying of the reaction solution, the final product BMI-P-PAEK powder is obtained.

4. The low-dielectric, high-flame-retardant polyphenylene ether composite cable material according to claim 3, characterized in that, The number-average molecular weight of the amino-terminated polyether ketone or amino-terminated polyether ketone is 5000-15000 g / mol, and the amino content is ≥0.95 mmol / g; the phosphorus-containing monomer DOPO-HQ is 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide.

5. The low-dielectric, high-flame-retardant polyphenylene ether composite cable material according to claim 3, characterized in that, The molar ratio of the terminal amino polyether ketone or the terminal amino polyether ketone and 4,4'-difluorobenzophenone is 1:1; the amount of the phosphorus-containing monomer DOPO-HQ added is determined based on the target phosphorus content of 1.0% to 2.2%; the amount of 4-maleimide benzoic acid added is 1.2 to 1.5 times the molar number of the terminal amino group of P-PAEK.

6. The low-dielectric, high-flame-retardant polyphenylene ether composite cable material according to claim 1, characterized in that, The preparation method of the polydopamine-modified hexagonal boron nitride is as follows: D1, disperse hexagonal boron nitride powder in Tris-HCl buffer solution with pH 8.0-9.0; D2, add dopamine hydrochloride and stir the reaction at room temperature for 20-30 h; D3, collect the solid by centrifugation, wash with deionized water, vacuum dry at 50-65℃, grind, and pass through a 200-mesh sieve to obtain PDA@h-BN powder.

7. The low-dielectric, high-flame-retardant polyphenylene ether composite cable material according to claim 6, characterized in that, The mass concentration of the hexagonal boron nitride in the Tris-HCl buffer is 5–10 mg / mL; the amount of dopamine hydrochloride added is 3%–5% of the mass of h-BN.

8. The low-dielectric, high-flame-retardant polyphenylene ether composite cable material according to claim 1, characterized in that, The polyphenylene ether is a hydroxyl-terminated polyphenylene ether resin with a melt index of 10–18 g / 10 min and an intrinsic viscosity of 0.35–0.42 dL / g; the glass transition temperature is ≥210℃; the hydrogenated styrene-butadiene block copolymer is a linear styrene block copolymer with a melt flow rate of 20–25 g / 10 min at 230°C / 5 kg and a viscosity of 800–1200 mPa·s for a 25% toluene solution; wherein the styrene content is 20%–32% by mass.

9. The low-dielectric, high-flame-retardant polyphenylene ether composite cable material according to claim 1, characterized in that, The ammonium polyphosphate has a degree of polymerization n>1000, water solubility <0.5% at room temperature for 2 hours, and a particle size D50 of 10-20 μm; the melamine has a purity >99.5% and a D50 particle size of 4-10 μm; the mass ratio of the ammonium polyphosphate to the melamine is (1.5-2.5):

1.

10. The low-dielectric, high-flame-retardant polyphenylene ether composite cable material according to claim 1, characterized in that, The antioxidant is at least one of antioxidant 1076, antioxidant 168, antioxidant 1010, antioxidant 1035, and antioxidant 1024; the polyethylene wax has a molecular weight of 3000-5000, a dropping point of 100-110℃, and an acid value <1mg KOH / g; the processing oil is a naphthenic oil or paraffin oil, with a kinematic viscosity of 90-110cSt at 40℃ and a pour point <-30℃.

11. A method for preparing the low-dielectric, high-flame-retardant polyphenylene ether composite cable material according to any one of claims 1 to 10, comprising the following steps: S1, the polydopamine surface-modified hexagonal boron nitride, compatibilizer, and hydrogenated styrene-butadiene block copolymer (20%–50% of the formulation amount) are melt-blended in a twin-screw extruder, granulated, and made into a thermally conductive masterbatch; the melt extrusion temperature is 160–200℃, the screw speed is 250–300 rpm, and the vacuum degree is -0.070–-0.080 MPa; S2, polyphenylene ether, residual hydrogenated styrene-butadiene block copolymer, thermally conductive masterbatch, bismaleimide-functionalized phosphorus-containing polyarylether ketone, antioxidant, polyethylene wax, and processing oil are thoroughly mixed and fed into the main feed, while ammonium polyphosphate and melamine are fed into the side feed. The mixture is melt-blended using a co-rotating twin-screw extruder. The melt extrusion temperature is 180–250°C, the screw speed is 250–350 rpm, and the vacuum degree is -0.075–-0.085 MPa. After melt extrusion, the mixture is cooled and pelletized to obtain the composite cable material.

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