New energy charging heat-conducting flame-retardant cable

Abstract

The invention relates to the technical field of cable production, and discloses a new energy charging heat-conducting flame-retardant cable which sequentially comprises a conductor layer, a heat-conducting insulating layer, a self-healing layer, a shielding layer, a mechanical enhancement layer and a flame-retardant outer sheath layer from inside to outside. The conductor layer is formed by a plurality of stranded tin-plated copper wires or nickel-plated copper wires; the heat-conducting insulating layer is composed of a crosslinked polyethylene matrix, a two-dimensional heat-conducting filler and phase-change temperature-adjusting microcapsules, the two-dimensional heat-conducting filler comprises a mixture of boron nitride nanosheets oriented by an electric field and graphene, and the mass fraction of the filler is 40%-55%; a core material of the phase-change temperature-adjusting microcapsule is a compound of paraffin and stearic acid. According to the scheme, trace rare earth and silver elements are introduced into the conductor to form a Cu-Ag-RE solid solution structure, so that the crystal integrity and the oxidation resistance of the conductor are remarkably improved; the structure still keeps excellent conductivity and bending resistance at high temperature, so that the cable can stably operate for a long time in a high-temperature and strong ultraviolet environment during charging, and the conductivity efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable production, in particular to a new energy charging heat-conducting flame-retardant cable. BACKGROUND

[0002] With the rapid development of new energy vehicle industry, the application scale of direct current fast charging pile and high power charging gun continues to expand. The charging system usually works under high voltage (600V-1000V) and large current (200A-600A) conditions, and the charging cable needs to meet the requirements of high conductivity, high temperature resistance, flame retardance and flexibility. However, in the prior art, the charging gun supporting cable still has the following main problems: the existing high-voltage charging cable mostly uses tinned copper or copper alloy stranded wire as the conductor, and is coated with cross-linked polyethylene or thermoplastic elastomer insulation layer. Because the thermal conductivity of the insulation material is low, when the high current is operated for a long time, hot spots are easily formed at the interface between the conductor and the insulation layer, which causes the local temperature rise to exceed 90℃, accelerating the insulation aging and resistance rise. Traditional flame-retardant charging cables often use bromine or chlorine flame retardants, which have good flame-retardant properties, but high smoke density and strong corrosiveness when burning, which do not meet the environmental protection and safety standards of the new energy vehicle industry. Some halogen-free systems using magnesium hydroxide and aluminum hydroxide require high filling ratio, which leads to decreased material flexibility and shortened bending life. During repeated bending, dragging and twisting of the charging gun cable, microcracks or damage channels are easily generated in the outer sheath and insulation layer. Due to the lack of self-healing mechanism, these defects can lead to water vapor penetration, electrical breakdown risk and increased cable scrap rate. SUMMARY

[0003] In view of the deficiencies of the prior art, the present application provides a new energy charging heat-conducting flame-retardant cable, which solves the above technical problems.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a new energy charging heat-conducting flame-retardant cable, which comprises, in order from the inside to the outside, a conductor layer, a heat-conducting insulation layer, a self-healing layer, a shielding layer, a mechanical reinforcing layer and a flame-retardant outer sheath layer.

[0005] The conductor layer is a plurality of twisted tinned copper wires or nickel-plated copper wires.

[0006] The heat-conducting insulation layer is composed of a cross-linked polyethylene matrix, a two-dimensional heat-conducting filler and phase change temperature regulating microcapsules, the two-dimensional heat-conducting filler includes a mixture of electric field oriented boron nitride nanosheets and graphene, and the mass fraction of the filler is 40%-55%.

[0007] The core material of the phase change temperature regulating microcapsules is a compound of paraffin and stearic acid, the melting point is 70-85℃, and the shell material is a silica coating layer, the mass fraction is 10%-20%.

[0008] The self-healing layer is composed of an amino-containing polysulfide polymer matrix and a microencapsulated epoxy resin repair agent, with a thickness of 0.3-0.8 mm;

[0009] The shielding layer comprises a metal braid layer and a heat-conductive polymer layer, the metal braid layer is made of tinned copper wire, and the heat-conductive polymer layer is polyethylene modified by nitrogen-containing silane;

[0010] The mechanical reinforcement layer is formed by mixing aramid fibers and carbon fibers;

[0011] The flame-retardant outer sheath layer is composed of polyolefin elastomer, phosphorus-nitrogen flame retardant, layered silicate and expandable graphite, the particle size of the expandable graphite is 100-150 mesh, and the content of the flame retardant is 25%-40%.

[0012] Preferably, the thickness of the heat-conductive insulation layer is 0.8-1.5 mm, and the thermal conductivity is not less than 2.0 W·m -1 ·K -1 ;

[0013] The average thickness of the boron nitride nanosheet is 50-100 nm, the thickness of the graphene sheet is 2-10 nm, and the mass ratio of the two is 3:2;

[0014] The two-dimensional heat-conductive filler is induced to orient by a high-frequency alternating electric field during the extrusion process, the electric field strength is 1-5 kV / cm, the frequency is 1-10 kHz, and the orientation angle error is not more than 5°.

[0015] Preferably, the microencapsulated epoxy repair agent comprises epoxy resin E-51 and polyamide curing agent, the mass ratio of the core material to the shell material is 7:3, and the particle size is 5-25 μm;

[0016] The metal braid density of the shielding layer is 85%-95%, and the thickness of the heat-conductive polymer layer is 0.3-0.6 mm.

[0017] Preferably, the phosphorus-nitrogen flame retardant in the flame-retardant outer sheath layer is a mixture of DOPO derivative and ammonium polyphosphate, with a mass ratio of 1:1, and the average thickness of the layered silicate is 50-200 nm;

[0018] The thickness of the flame-retardant outer sheath layer is 1.5-2.5 mm, the limiting oxygen index is not less than 34%, and the volume resistivity is not less than 1×101 4 Ω·cm.

[0019] Preferably, a silane coupling agent interface layer is arranged between the conductor layer and the heat-conductive insulation layer, the coupling agent is γ-aminopropyl triethoxysilane, and the coating amount is 0.5-1.0 wt%.

[0020] A preparation method of a new energy charging heat-conductive flame-retardant cable, comprising the following steps:

[0021] S1. Mix cross-linked polyethylene matrix, boron nitride nanosheets and graphene, and knead in a twin-screw extruder at 180-200℃ for 5-10 min;

[0022] S2. Apply an alternating electric field of 1-5kV / cm to orient the filler radially, and then add phase change temperature-regulating microcapsules in the low temperature range (80-100℃) and extrude to form a thermally conductive insulating layer;

[0023] S3. A self-healing layer is formed by coating with an amino-containing polysulfide polymer and a microencapsulated epoxy resin repair agent solution.

[0024] S4. Wrap the metal braided layer and extrude the thermally conductive polymer layer to form a shielding layer;

[0025] S5. Braided aramid fibers and carbon fibers form a mechanical reinforcement layer;

[0026] S6. Extruding a polyolefin elastomer composite containing phosphorus and nitrogen flame retardant, layered silicate and expandable graphite into the outer layer to obtain a flame-retardant outer sheath layer.

[0027] S7. After cross-linking curing, cooling, surface plasma activation and performance testing, the finished cable is obtained.

[0028] Preferably, the preparation of the cross-linked polyethylene matrix includes the following steps:

[0029] (1) Mix low-density polyethylene and dicumyl peroxide at a ratio of 1-2 wt%, and preheat at 110-130°C for 10-15 min under a nitrogen atmosphere;

[0030] (2) Add ethylene-vinyl acetate copolymer (EVA) and silane coupling agent KH-550, and mix for 5 to 8 minutes;

[0031] (3) The polyethylene matrix particles with cross-linking pre-reactive properties are formed by melt blending in a twin-screw extruder at 180-200°C and used for extrusion of thermally conductive insulation layer.

[0032] Preferably, the preparation of the phase change temperature-regulating microcapsules includes the following steps:

[0033] (1) Heat paraffin and stearic acid at a mass ratio of 3:1 to 90-95℃ until they melt evenly;

[0034] (2) Add the surfactant sodium dodecylbenzenesulfonate (SDBS) under stirring conditions and form an oil / water emulsion using a high-speed shear emulsifier;

[0035] (3) Add tetraethoxysilane (TEOS) dropwise to the emulsion system and carry out in-situ hydrolysis and polycondensation reaction under ammonia catalysis for 2-3 hours;

[0036] (4) Centrifugal separation, washing and vacuum drying to obtain silica-coated microcapsules with a particle size of 5-20 μm and a shell thickness of 200-400 nm.

[0037] Preferably, the formation of the self-healing layer in step S3 comprises the following process:

[0038] (1) Dissolve the amino-containing polysulfide polymer in an acetone / ethanol mixed solvent with a solid content of 30%-40%;

[0039] (2) Add the microencapsulated epoxy resin repair agent, stir and disperse for 30 min, and the microcapsule content is 15-25 wt%;

[0040] (3) Uniformly coat the mixed solution on the outer surface of the thermal conductive insulation layer by continuous dip coating, and control the coating thickness to be 0.3-0.8 mm;

[0041] (4) Dry at 60-80°C under hot air conditions for 1-2 h to form a dense and repeatable self-healing layer.

[0042] Preferably, the cross-linking, cooling and surface plasma activation in step S7 comprise the following process:

[0043] (1) Place the cable structure in a hot air environment at 170-190°C for cross-linking and curing for 30-45 min to ensure complete cross-linking of the polyethylene and thermal conductive polymer layer;

[0044] (2) Rapidly cool to room temperature using circulating cooling water to inhibit stress shrinkage and interlayer peeling;

[0045] (3) Use a radio frequency plasma device (power 100-200 W, processing time 30-90 s) to activate the surface of the outer sheath to improve the surface polarity and adhesion energy, providing interface activity for subsequent code spraying and sheath bonding.

[0046] Compared with the prior art, the present application provides a new energy charging thermal conductive flame-retardant cable, which has the following beneficial effects:

[0047] (1) The present scheme introduces trace amounts of rare earth and silver elements into the conductor to form a Cu-Ag-RE solid solution structure, which significantly improves the crystalline integrity and oxidation resistance of the conductor; this structure still maintains excellent electrical conductivity and bending resistance at high temperatures, allowing the cable to operate stably for a long time in a high-temperature, strong ultraviolet environment during charging, with an increase in electrical efficiency of about 5%-8%.

[0048] (2) Graphene or boron nitride high-thermal-conductivity fillers are used to form a continuous heat conduction channel by in-situ compounding in the polyimide matrix at high temperature; this thermal conductive layer significantly reduces the temperature rise of the cable during operation, while inhibiting the accumulation of local hot spots and prolonging the service life of the insulation layer.

[0049] (3) Set a phase change microcapsule layer between the insulating layer and the thermal conductive layer, encapsulate paraffin or fatty alcohol phase change materials; when the cable temperature rises to the phase change point, the microcapsule absorbs latent heat and releases heat, realizing dynamic temperature buffering; effectively balancing the internal temperature distribution of the cable, avoiding thermal stress concentration, and improving the thermal cycle life to more than 2000 times. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 The flow chart of the cable manufacturing method of the present application. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0052] Example 1:

[0053] Conductor layer: a tinned copper wire with a diameter of 0.20 mm is twisted into a plurality of strands, the number of twisted strands is 37, and the total cross-sectional area is 6 mm 2 The conductor surface is naturally dried after ultrasonic cleaning with ethanol to enhance the conductivity and oxidation resistance.

[0054] Thermal conductive insulating layer: base material: cross-linked polyethylene (XLPE, model DFDA-5450) as the main body resin;

[0055] Thermal conductive filler: boron nitride nanosheet (BNNS, thickness about 80 nm) and graphene (thickness about 5 nm) are mixed in a mass ratio of 3:2;

[0056] Phase change temperature regulating microcapsule: the core material is a compound of paraffin and stearic acid (3:1) with a melting point of 78℃, the shell layer is a silica coating layer with a particle size of about 10 μm, and the addition amount is 15% of the mass of the thermal conductive layer;

[0057] Overall ratio: cross-linked polyethylene 45wt%, BNNS+graphene mixed filler 45wt%, phase change microcapsule 10wt%.

[0058] Thickness and performance: the molding thickness is 1.2 mm, the thermal conductivity is 2.35 W·m -1 ·K -1 , and the breakdown strength is 25 kV / mm.

[0059] Self-healing layer: base: amino-containing polysulfide polymer (molecular weight about 20000);

[0060] Repair agent: microencapsulated epoxy resin, core material is E-51 epoxy resin and polyamide curing agent, mass ratio 7:3, particle size 15 μm;

[0061] Ratio: repair agent content 20wt%, dispersed with acetone / ethanol (1:1) mixed solvent, coating thickness 0.5mm;

[0062] Drying conditions: hot air drying at 70℃ for 1.5h, forming a dense self-healing layer.

[0063] Shielding layer: metal braid layer: tinned copper wire diameter 0.12mm, braid density 90%;

[0064] Thermally conductive polymer layer: polyethylene modified with nitrogen-containing silane (aminopropyl silane modified), thickness 0.5mm, thermal conductivity about 1.1 W·m -1 ·K -1 .

[0065] Mechanical reinforcement layer: formed by mixing 300D aramid fiber and 24K carbon fiber in a 1:1 structure, thickness about 0.6mm, tensile strength more than 150MPa.

[0066] Flame-retardant outer sheath layer: matrix: polyolefin elastomer (POE, model ENGAGE8200);

[0067] Flame retardant: DOPO derivative and ammonium polyphosphate (APP) compounded at a mass ratio of 1:1, content 35wt%;

[0068] Filler: layered silicate thickness 100nm, expandable graphite particle size 120 mesh, addition amount 5wt% and 8wt% respectively;

[0069] Thickness and performance: outer sheath thickness 2.0mm, oxygen index 35.6%, volume resistivity 1.2×10 14 Ω·cm, flame retardant level reaches VW-1 standard.

[0070] Interface coupling layer: γ-aminopropyl triethoxysilane coupling agent is applied between the conductor layer and the thermally conductive insulating layer to improve the interlayer adhesion and interface thermal conductivity stability.

[0071] S1: preparation of crosslinked polyethylene matrix composite

[0072] Under nitrogen atmosphere, low density polyethylene (LDPE) and dicumyl peroxide (DCP) were mixed and preheated to 120℃ for 15min; EVA and KH-550 coupling agent were added and mixed for 8min, then melt blended in a 180℃ double screw extruder to obtain crosslinked pre-reaction particles.

[0073] S2: preparation of thermally conductive insulating layer

[0074] At 180–200°C, the XLPE matrix and the BNNS / graphene mixture were uniformly mixed for 5 min.

[0075] An alternating electric field (3kV / cm, frequency 5kHz) is applied to induce the packing to orient radially.

[0076] After cooling to 90°C, phase change microcapsules are added and mixed evenly. Then, the mixture is extruded and coated onto the conductor layer to form a 1.2 mm thick thermally conductive insulating layer.

[0077] S3: Formation of a self-healing layer

[0078] Prepare an amino-containing polysulfide polymer solution (solid content 35%), add 20wt% microencapsulated epoxy repair agent, stir and disperse for 30min; apply it to the outer surface of the thermally conductive insulation layer by continuous dip coating, and dry for 1.5h to form a self-healing layer.

[0079] S4: Form a shielding layer

[0080] The outer layer is wrapped with tin-plated copper wire (90% density) and a thermally conductive polyethylene layer is extruded, with the thickness controlled at 0.5 mm.

[0081] S5: Formation of a mechanical reinforcement layer

[0082] A blend of aramid and carbon fiber is woven and wound around the cable surface, with tension controlled at 5–7 N.

[0083] S6: Forms a flame-retardant outer sheath layer

[0084] After uniformly mixing POE, DOPO / APP flame retardant, layered silicate and expandable graphite, the mixture is extruded at 180°C to a thickness of 2.0 mm.

[0085] S7: Crosslinking Curing and Surface Treatment

[0086] After cabling, crosslinking and curing are carried out in hot air at 180℃ for 40 minutes;

[0087] Cooled to 25°C using circulating cooling water;

[0088] Finally, the outer sheath surface was activated with radio frequency plasma (150W, 60s) to improve surface energy and adhesion.

[0089] Example 2

[0090] Conductor layer: 0.18mm diameter silver-plated copper wire, stranded in 61 strands, with a total cross-sectional area of ​​6mm². 2 ;

[0091] After the conductor is cleaned with dilute sulfuric acid to remove the oxide film, it is rinsed with ethanol and vacuum dried at 60°C for 30 minutes to improve conductivity and interface cleanliness.

[0092] Thermal conductive insulation layer: matrix material: high heat resistance cross-linked polyethylene (XLPE, model ACR-7320) and ethylene-vinyl acetate copolymer (EVA, VA content 18%) were compounded, mass ratio 7:3;

[0093] Thermal conductive filler: hexagonal boron nitride nanosheet (thickness about 60 nm) and graphene oxide (GO) composite filler, mass ratio 4:1;

[0094] Phase change temperature regulating microcapsule: core material is paraffin / myristic acid compound (2:1), melting point about 82℃, shell layer is polyurea-polyurethane (PUU) double-layer coating structure, particle size 8μm, addition amount is 12wt% of the total mass of the thermal conductive insulation layer;

[0095] Overall ratio: XLPE / EVA matrix 60wt%, BNNS / GO filler 28wt%, phase change microcapsule 12wt%;

[0096] Molding thickness and performance: insulation layer thickness 1.0mm, thermal conductivity 2.65W·m -1 ·K -1 , dielectric strength 28kV / mm, thermal response hysteresis temperature difference less than 2℃.

[0097] Self-healing layer: matrix: using amino-containing polysulfide polyether (Mn≈25000, containing active -NH2 group 2.1mmol / g);

[0098] Repair agent: microencapsulated epoxy repair agent, core material is bisphenol A type epoxy resin E-44 and fatty amine curing agent (2:1), shell layer is polyurea / silicon dioxide composite coating, particle size 10μm;

[0099] Ratio: repair agent content 25wt%, using toluene / isopropyl alcohol (3:1) solvent ultrasonic dispersion 20min;

[0100] Coating method and thickness: using spray-spin coating composite method, film thickness 0.4mm;

[0101] Drying and film forming conditions: hot air drying at 80℃ for 2h, forming continuous dense self-healing layer, surface energy about 52mN / m.

[0102] Shielding layer: metal layer: double-layer braided tin-plated copper strip, braiding density 92%;

[0103] Thermally conductive polymer layer: using aminopropyl-trimethoxysilane modified polyethylene / polyimide (PE / PI) blend layer, mass ratio 8:2, thickness 0.4mm, thermal conductivity 1.3W·m -1 ·K -1 , volume resistivity 1.5×10 14 Ω·cm.

[0104] Mechanical reinforcement layer:

[0105] Structure: Aramid fiber (400D) and T700 carbon fiber are interwoven into a three-dimensional woven layer.

[0106] Thickness and tension control: thickness is about 0.8mm, tension is maintained at 6±0.5N;

[0107] Mechanical properties: tensile strength reaches 170MPa, impact toughness increases by 20%.

[0108] Flame-retardant outer sheath layer:

[0109] Matrix: polyolefin elastomer POE (model ENGAGE8411) and linear low-density polyethylene (LLDPE, model 7050) are compounded with a mass ratio of 6:4;

[0110] Flame-retardant system: 9,10-dihydro-9-oxo-10-phosphaphenanthrene (DOPO) derivative and nitrogen-phosphorus copolymer ammonium polyphosphate (APP-II) with a mass ratio of 2:1, total content of 30wt%;

[0111] Inorganic filler: layered double hydroxide magnesium hydroxide (LDH, sheet thickness 70nm) and expanded graphite (particle size 100 mesh) are added at 6wt% and 10wt% respectively;

[0112] Molding thickness and performance: thickness 2.3mm, oxygen index reaches 37%, smoke density ratio is 0.28, flame-retardant grade UL94 V-0.

[0113] Interface coupling layer: γ-glycidoxypropyltrimethoxysilane (KH-560) coupling agent is applied between the conductor and the insulating layer, with a concentration of 0.5wt%, and isopropanol as the solvent, soaked for 2min and dried, forming an interface layer about 2μm thick, improving the interfacial adhesion and thermal conductivity continuity.

[0114] Manufacturing steps:

[0115] S1: Preparation of cross-linked polyethylene matrix composite

[0116] LDPE, EVA, DCP and KH-550 are added to a high-speed mixer, heated to 125℃ for 10min;

[0117] Mixing in a twin-screw extruder under nitrogen atmosphere at 185℃, speed 100rpm, to obtain cross-linked pre-reaction particles.

[0118] S2: Preparation of thermal conductive insulating layer

[0119] Mix the cross-linked pre-reaction particles and BNNS / GO filler at 185℃ for 5min;

[0120] Apply alternating electric field (4kV / cm, frequency 8kHz) to orient filler radially;

[0121] Cool down to 95℃ and add phase change microcapsules and mix well;

[0122] Extrude the conductor layer to form a 1.0mm thick thermal conductive insulation layer.

[0123] S3: Forming self-healing layer

[0124] Prepare a solution of polyether polysulfide with a solid content of 35wt%, add 25wt% of microencapsulated repair agent, and stir for 30min;

[0125] Uniformly coat the surface of the insulation layer using spray-spinning method;

[0126] Dry at 80℃ for 2h to form a self-healing film.

[0127] S4: Forming shielding layer

[0128] Wrap the tin-plated copper strip and extrude the thermal conductive polymer layer, with a thickness controlled at 0.4mm.

[0129] S5: Forming mechanical reinforcement layer

[0130] Use three-dimensional weaving structure to cover aramid / carbon fiber composite layer, with tension control at 6N.

[0131] S6: Forming flame-retardant outer sheath layer

[0132] After mixing according to the formula, extrude at 185℃ to form a flame-retardant layer with a thickness of 2.3mm.

[0133] S7: Crosslinking and curing and surface plasma activation

[0134] After cabling, place in an air circulation oven at 185℃ for crosslinking and curing for 45min;

[0135] Cool down to 25℃ with circulating cooling water;

[0136] Again, treat the surface of the outer sheath with radio frequency plasma (power 180W, time 80s) to improve surface energy and printing adhesion.

[0137] Example 3

[0138] Conductor layer: Conductor material: Use nickel-plated copper alloy wire (nickel content 1.5wt%, type CuNi1.5), single wire diameter 0.25mm, 37-strand bundle twist, total cross-sectional area 10mm²;

[0139] Surface treatment: 0.5wt% amino silane (KH-602) solution was used for infiltration coating, dried at room temperature and then baked at 100℃ for 30min, forming a stable conductor interface layer, which can improve the interface bonding strength and oxidation resistance;

[0140] Conductor resistance: 2.9×10 -3 Ω·m at 20℃, with better temperature resistance than 200℃.

[0141] Thermal conductive insulation layer: base material: high melting point silane cross-linked polyethylene (XLPE, model DFDA-6180) and polyolefin elastomer POE (ENGAGE8452) composite, mass ratio 6:4;

[0142] Thermal conductive filler: three-dimensional structure carbon nanotube (CNT, diameter 20nm, length 10μm) and cubic boron nitride (c-BN) mixed filler, mass ratio 2:3, total filling amount 35wt%;

[0143] Phase change temperature regulating microcapsule: core material is decanoic acid-lauric acid eutectic (melting point 72℃), shell layer is polysiloxane composite layer, particle size 6μm, addition amount is 10wt% of the total mass of the insulation layer;

[0144] Processing method: mixing at 185℃, 100rpm for 6min, using high voltage electric field (5kV / cm, frequency 10kHz) for filler orientation induction;

[0145] Molding thickness and performance: thickness 1.5mm, thermal conductivity increased to 3.05W·m -1 ·K -1 , breakdown strength reached 30kV / mm, volume resistivity 3.8×10 15 Ω·cm.

[0146] Self-healing layer: base material: hydroxyl-containing polysulfide polyether (Mn≈30000, active group content 3.5mmol / g);

[0147] Repairing agent: microencapsulated two-component silicone system (component A is methyl vinyl silicone oil, component B is crosslinking agent containing platinum catalyst), particle size 12μm, shell layer is polyimide composite coating;

[0148] Proportion and solvent system: repairing agent accounts for 30wt% of the total mass of the self-healing layer, solvent is dichloromethane / ethanol (2:1), ultrasonic dispersion for 40min;

[0149] Coating method and thickness: electrostatic spraying film forming, thickness 0.6mm;

[0150] Curing method: two-stage treatment of ultraviolet curing (365nm, 20min) + 80℃ thermal curing 1h, forming a cross-linked self-healing network.

[0151] Shielding layer: Structural composition: double-layer shielding structure; inner layer is plated nickel copper wire weaving (density 88%), outer layer is conductive polymer layer;

[0152] Conductive layer material: polyaniline / polyvinyl alcohol (PANI / PVA) composite conductive layer, thickness 0.4mm, surface resistivity less than 1.2Ω / sq, with good electromagnetic shielding and UV resistance.

[0153] Mechanical reinforcement layer: fiber system: aramid 1414 fiber (600D) and basalt fiber mixed, ratio 1:1;

[0154] Structural form: two-way twill weave structure, thickness 0.9mm;

[0155] Performance index: tensile strength up to 180MPa, minimum bending radius can reach 5D, impact energy absorption rate increased by 25%.

[0156] Flame-retardant outer sheath layer: matrix: using fluorinated ethylene propylene copolymer (FEP) and polyolefin elastomer (POE) blending, mass ratio 7:3;

[0157] Flame-retardant system: DOPO derivative, nitrogen-phosphorus intumescent system and nano-aluminum oxide (Al2O3, particle size 50nm) synergistic flame-retardant, mass ratio of the three is 2:2:1, total addition amount 35wt%;

[0158] Anti-aging additives: add 0.5wt% hindered amine light stabilizer (HALS-770) and 0.2wt% ultraviolet agent UV-531;

[0159] Molding conditions and properties: extrusion temperature 190℃, thickness 2.5mm, oxygen index up to 38.2%, flame retardant grade UL94V-0, weathering life >8000h (xenon lamp aging test).

[0160] Interface coupling layer: apply epoxy modified silane coupling agent (γ-glycidoxypropyl triethoxysilane KH-560) between the conductor and the insulating layer, concentration 0.8wt%, after corona treatment, spray, thickness about 1.5μm;

[0161] Introduce fluorosilane coupling agent FAS-17 interface layer between the reinforcement layer and the outer sheath, thickness 2μm, to improve weather resistance and thermal stability.

[0162] Manufacturing steps

[0163] S1: preparation of crosslinked polyethylene matrix composite

[0164] Put LDPE, POE, DCP and KH-602 into the internal mixer, heat to 120℃ and react for 12min;

[0165] Crosslinked pre-reaction particles were prepared by extrusion mixing at 190℃ under nitrogen protection, with a rotation speed of 80rpm.

[0166] S2: Preparation of thermal conductive insulation layer

[0167] XLPE / POE was mixed with CNTs and c-BN fillers at 185℃ for 8min,

[0168] A high-frequency electric field of 5kV / cm (10kHz) was applied to promote the orientation of the fillers;

[0169] The temperature was cooled to 100℃, and phase change microcapsules were added to form a 1.5mm thick insulation layer by extrusion coating the conductor.

[0170] S3: Formation of self-healing layer

[0171] A solution of hydroxyl-containing polysulfide polyether (solid content 30wt%) was prepared, and 30wt% of microcapsule repair agent was added and ultrasonically dispersed for 40min;

[0172] Electrostatic spraying was used to coat the outer surface of the insulation layer;

[0173] UV irradiation (365nm, 20min) and 80℃ thermal curing for 1h were used to form the self-healing film.

[0174] S4: Formation of double-layer shielding layer

[0175] A layer of nickel-plated copper wire (density 88%) was first wound, and then a layer of conductive PANI / PVA (thickness 0.4mm) was extruded.

[0176] S5: Formation of mechanical reinforcement layer

[0177] Basalt / aramid mixed layer was used, with a tension control of 7N and a coating thickness of 0.9mm.

[0178] S6: Formation of flame-retardant outer sheath layer

[0179] The ingredients were mixed and extruded at 190℃ to form a 2.5mm thick outer sheath.

[0180] S7: Crosslinking and surface treatment

[0181] After cabling, crosslinking was performed in an air circulation oven at 185℃ for 45min;

[0182] Cooling to 25℃;

[0183] The outer sheath surface was treated with radio frequency plasma (power 200W, action time 100s) to improve surface adhesion energy and weather resistance.

[0184] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A new energy charging thermally conductive and flame-retardant cable, characterized in that, From the inside out, it includes a conductor layer, a thermally conductive insulating layer, a self-healing layer, a shielding layer, a mechanical reinforcement layer, and a flame-retardant outer sheath layer. The conductor layer is a multi-strand stranded tin-plated copper wire or a nickel-plated copper wire; The thermally conductive insulating layer is composed of a cross-linked polyethylene matrix, a two-dimensional thermally conductive filler, and a phase change temperature-regulating microcapsule. The two-dimensional thermally conductive filler includes a mixture of boron nitride nanosheets and graphene oriented by an electric field, with a filler mass fraction of 40% to 55%. The core material of the phase change temperature-regulating microcapsule is a compound of paraffin and stearic acid with a melting point of 70-85°C, and the shell material is a silica coating layer with a mass fraction of 10%-20%. The self-healing layer is composed of an amino-containing polysulfide polymer matrix and a microencapsulated epoxy resin repair agent, with a thickness of 0.3–0.8 mm. The shielding layer includes a metal braided layer and a thermally conductive polymer layer. The metal braided layer is made of tin-plated copper wire, and the thermally conductive polymer layer is nitrogen-containing silane-modified polyethylene. The mechanical reinforcement layer is formed by weaving together aramid fibers and carbon fibers; The flame-retardant outer sheath is composed of polyolefin elastomer, phosphorus-nitrogen flame retardant, layered silicate and expandable graphite, wherein the expandable graphite has a particle size of 100-150 mesh and the flame retardant content is 25%-40%.

2. The new energy charging thermally conductive and flame-retardant cable according to claim 1, characterized in that, The thickness of the thermally conductive insulating layer is 0.8–1.5 mm, and the thermal conductivity is not less than 2.0 W·m. -1 ·K -1 ; The average thickness of the boron nitride nanosheets is 50–100 nm, the thickness of the graphene sheets is 2–10 nm, and the mass ratio of the two is 3:

2. The two-dimensional thermally conductive filler is oriented by a high-frequency alternating electric field during the extrusion process. The electric field strength is 1-5 kV / cm, the frequency is 1-10 kHz, and the guiding angle error is no greater than 5°.

3. The new energy charging thermally conductive and flame-retardant cable according to claim 1, characterized in that, The microencapsulated epoxy repair agent comprises epoxy resin E-51 and polyamide curing agent, with a core material to shell material mass ratio of 7:3 and a particle size of 5-25μm. The metal braiding density of the shielding layer is 85% to 95%, and the thickness of the thermally conductive polymer layer is 0.3 to 0.6 mm.

4. The new energy charging thermally conductive and flame-retardant cable according to claim 1, characterized in that, The flame-retardant outer sheath layer contains a mixture of DOPO derivatives and ammonium polyphosphate as the phosphorus-nitrogen flame retardant, with a mass ratio of 1:1, and the average thickness of the layered silicate is 50–200 nm.

5. The new energy charging thermally conductive and flame-retardant cable according to claim 1, characterized in that, The flame-retardant outer sheath layer has a thickness of 1.5–2.5 mm, a limiting oxygen index of not less than 34%, and a volume resistivity of not less than 1 × 10¹⁸. 4 Ω·cm.

6. The new energy charging thermally conductive and flame-retardant cable according to claim 1, characterized in that, A silane coupling agent interface layer is provided between the conductor layer and the thermally conductive insulating layer. The coupling agent is γ-aminopropyltriethoxysilane, and the coating amount is 0.5-1.0 wt%.

7. The new energy charging thermally conductive and flame-retardant cable according to claim 1, characterized in that, The cable manufacturing process includes the following steps: S1. Mix cross-linked polyethylene matrix, boron nitride nanosheets and graphene, and knead in a twin-screw extruder at 180-200℃ for 5-10 min; S2. Apply an alternating electric field of 1-5kV / cm to orient the filler radially, and then add phase change temperature-regulating microcapsules in the low temperature range (80-100℃) and extrude to form a thermally conductive insulating layer; S3. A self-healing layer is formed by coating with an amino-containing polysulfide polymer and a microencapsulated epoxy resin repair agent solution. S4. Wrap the metal braided layer and extrude the thermally conductive polymer layer to form a shielding layer; S5. Braided aramid fibers and carbon fibers form a mechanical reinforcement layer; S6. Extruding a polyolefin elastomer composite containing phosphorus and nitrogen flame retardant, layered silicate and expandable graphite into the outer layer to obtain a flame-retardant outer sheath layer. S7. After cross-linking curing, cooling, surface plasma activation and performance testing, the finished cable is obtained.

8. A new energy charging thermally conductive and flame-retardant cable according to claim 7, characterized in that, The preparation of the cross-linked polyethylene matrix includes the following steps: (1) Mix low-density polyethylene and dicumyl peroxide at a ratio of 1-2 wt%, and preheat at 110-130°C for 10-15 min under a nitrogen atmosphere; (2) Add ethylene-vinyl acetate copolymer (EVA) and silane coupling agent KH-550, and mix for 5 to 8 minutes; (3) The polyethylene matrix particles with cross-linking pre-reactive properties are formed by melt blending in a twin-screw extruder at 180-200°C and used for extrusion of thermally conductive insulation layer.

9. A new energy charging thermally conductive and flame-retardant cable according to claim 7, characterized in that, The preparation of the phase change temperature-regulating microcapsules includes the following steps: (1) Heat paraffin and stearic acid at a mass ratio of 3:1 to 90-95℃ until they melt evenly; (2) Add the surfactant sodium dodecylbenzenesulfonate (SDBS) under stirring conditions and form an oil / water emulsion using a high-speed shear emulsifier; (3) Add tetraethoxysilane (TEOS) dropwise to the emulsion system and carry out in-situ hydrolysis and polycondensation reaction under ammonia catalysis for 2-3 hours; (4) After centrifugation, washing and vacuum drying, silica-coated microcapsules with a particle size of 5-20 μm and a shell thickness of 200-400 nm were obtained.

10. A new energy charging thermally conductive and flame-retardant cable according to claim 7, characterized in that, The formation of the self-healing layer in step S3 includes the following processes: (1) Dissolve the amino-containing polysulfide polymer in an acetone / ethanol mixed solvent with a solid content of 30% to 40%; (2) Add microencapsulated epoxy resin repair agent, stir and disperse for 30 min, the microcapsule content is 15-25 wt%; (3) The mixed solution is uniformly coated onto the outer surface of the thermally conductive insulating layer using a continuous dip-coating method, and the coating thickness is controlled to be 0.3 to 0.8 mm; (4) Dry in hot air at 60-80℃ for 1-2 hours to form a dense and re-healing self-healing layer.

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