A wire for wire harness with a temperature resistance of 850℃ and its preparation method

Abstract

This application relates to the field of wires and cables, specifically disclosing a wire for a harness with a temperature resistance of 850℃, its preparation method, and its application. The wire for a harness with a temperature resistance of 850℃ comprises, from the inside out, a high-temperature resistant conductor, a high-temperature resistant heat insulation layer, a flame-retardant buffer layer, and an insulating protective layer. The high-temperature resistant conductor is a conductor core formed by stranding at least one strand of nickel-plated copper wire. The high-temperature resistant heat insulation layer is a stranded quartz fiber yarn covering the high-temperature resistant conductor. The flame-retardant buffer layer is a ceramicized silicone rubber tape wrapped around the high-temperature resistant heat insulation layer. The insulating protective layer is a perfluoroalkoxy resin layer extruded over the flame-retardant buffer layer. It maintains energization for ≥30 minutes under thermal runaway conditions, is not easily corroded or aged in acidic battery environments, and has a small bending radius, meeting the requirements for wiring in confined and tortuous environments.

Description

Technical Field

[0001] This application relates to the field of wire and cable technology, and more specifically, it relates to a wire for wire harnesses with a temperature resistance of 850°C and a method for preparing the same. Background Technology

[0002] With the rapid development of the new energy industry, a large number of power batteries and energy storage batteries have been put into practical application, and battery safety has received increasing attention. Whether it is the relatively mature lithium-ion battery technology at present or the all-solid-state battery that may be used on a large scale in the future, thermal runaway remains a core safety problem that cannot be avoided. Thermal runaway refers to a chain reaction phenomenon caused by various factors such as mechanical abuse, electrical abuse, and thermal abuse. This process is rapid and irreversible, releasing a large amount of heat and harmful gases in a very short time, with temperature peaks reaching over 850°C, which can easily cause the battery to catch fire or even explode.

[0003] In existing battery systems, the wiring harnesses used around the battery generally have low temperature resistance ratings. The long-term temperature resistance of common insulation materials are as follows: polyvinyl chloride (PVC) 70-105℃, cross-linked polyolefin (XLPE / XLPO) 90-125℃, silicone rubber 150-200℃, and perfluoroalkoxy resin (PFA) 260℃. These cables typically consist of only a conductor and a single layer of insulation. When a battery experiences thermal runaway, the extreme high temperature exceeding 850℃ far surpasses the insulation layer's tolerance limit. The high-temperature heat is rapidly conducted along the copper conductor, causing the insulation layer to melt and break down quickly, leading to short circuits, arcing, and fires. This further expands the scope of the thermal runaway accident, seriously threatening personnel escape and property protection.

[0004] For high-temperature cables with a resistance level of 500℃ or higher, existing technologies have a certain research foundation, but there are still obvious shortcomings when applying them to new energy battery-related scenarios. The background technology of Chinese invention patent application CN201610174631.4 summarizes the existing 500℃ high-temperature cables in the domestic market. Traditional solutions generally adopt a composite insulation structure of "conductor + mica wrapping + glass fiber braiding + sizing agent coating and curing". This type of cable has the following shortcomings: First, the manufacturing process is complex, involving multiple wrapping, braiding, impregnation, and curing processes, making it difficult to achieve large-scale promotion and application; Second, the sizing agent is usually composed of a composite of organosilicon resin and inorganic powder. Organosilicon materials have poor resistance to battery acid corrosion. During long-term operation inside the battery pack, if there is slight leakage from the battery, the acidic electrolyte or its decomposition products will gradually corrode the insulation layer, leading to a gradual decline in insulation performance or even failure, posing a serious risk of leakage. To address the risk of insufficient acid corrosion resistance in the aforementioned insulation layer, this invention application proposes a technical solution to replace the outer sheath of the cable with a corrugated sleeve formed by welding and rolling stainless steel strips, utilizing the metal material as an insulating layer to protect the internal insulation structure. This solution belongs to another type of high-temperature cable design approach, namely using a metal sheath to achieve thermal barrier and physical protection. However, this structure is more suitable for power cables with larger cross-sectional areas. For wire harnesses (typically with conductor cross-sectional areas below 0.5 mm²), the stainless steel strip welding and rolling process is difficult to achieve small-size forming. Furthermore, the introduction of a metal sheath significantly increases the overall rigidity of the cable and drastically reduces its flexibility, making it difficult to meet the actual laying requirements of confined spaces and complex, winding wiring paths, such as those found in new energy vehicles.

[0005] In summary, existing high-temperature cables cannot simultaneously meet the following key requirements: sufficient flexibility to adapt to wiring needs in confined and winding environments; long-term reliable operation under battery acid leakage conditions; and the ability to maintain power supply for a certain period under extreme conditions of battery thermal runaway at 850℃, thus buying time for personnel escape and emergency rescue. Therefore, there is an urgent need to develop a new type of wire harness that achieves a comprehensive balance in terms of temperature resistance, acid corrosion resistance, and bending performance. Summary of the Invention

[0006] To simultaneously meet the requirements of flexibility, acid corrosion resistance, and temperature resistance of wires for wire harnesses, this application provides a wire for wire harnesses with a temperature resistance of 850℃ and a method for its preparation.

[0007] In the first aspect, this application provides a wire for a wire harness that can withstand temperatures up to 850°C, using the following technical solution:

[0008] A wire harness with a temperature resistance of 850℃ comprises, from the inside out, a high-temperature resistant conductor, a high-temperature resistant heat insulation layer, a flame-retardant buffer layer, and an insulating protective layer; the high-temperature resistant conductor comprises a conductor core formed by at least one strand of nickel-plated copper wire twisted together; the high-temperature resistant heat insulation layer is a stranded quartz fiber yarn wrapped around the high-temperature resistant conductor; the flame-retardant buffer layer is a ceramicized silicone rubber tape wrapped around the high-temperature resistant heat insulation layer; and the insulating protective layer is a perfluoroalkoxy resin layer extruded around the flame-retardant buffer layer.

[0009] By adopting the above technical solutions, nickel-plated copper stranded wire is used. The nickel layer effectively prevents copper from oxidizing drastically at 850℃, ensuring continuous circuit conduction under extreme conditions. The multi-strand stranded structure reduces the risk of thermal stress fracture at high temperatures. The high-temperature insulation layer uses high-purity quartz fiber yarn, which, compared to ordinary glass fiber yarn, high-silica fiber yarn, alumina fiber yarn, and aluminosilicate ceramic fiber yarn, has a low thermal conductivity and high temperature resistance. It can significantly block external heat from being conducted to the interior or subsequent layers through the conductor, serving as the core barrier for heat insulation. The flame-retardant buffer layer uses ceramicized silicone rubber tape, which spontaneously sintersulates at temperatures above 500℃ to form a dense, hard ceramic shell. This not only further blocks flames and heat but also provides shock resistance, even against the outer layer of perfluoroalkoxy. Even when the base resin is damaged at ultra-high temperatures, the ceramic shell can still continuously provide insulation protection, meeting the escape and rescue requirements of ≥30 minutes of power supply at 850℃. The insulating protective layer uses perfluoroalkoxy resin extruded onto the flame-retardant buffer layer, which itself has a continuous operating temperature of up to 260℃. After being insulated by the internal high-temperature resistant insulation layer and the flame-retardant buffer layer, its actual temperature resistance is significantly reduced, maintaining structural integrity throughout the entire thermal runaway cycle. Moreover, the outermost perfluoroalkoxy resin is composed of strong CF bonds, which has extremely high chemical inertness and long-term resistance to acidic seepage such as sulfuric acid and hydrofluoric acid that may occur in the battery pack. This fundamentally solves the defects of traditional organosilicon wetting agents that are not resistant to battery acid corrosion and have a high risk of leakage after long-term operation, making it suitable for use throughout the entire battery life cycle.

[0010] In addition, multi-strand stranded nickel-plated copper wire is used as the conductor, which has good flexibility. Quartz fiber is wrapped in strands to retain good toughness and avoid hardening caused by rigid wrapping. The ceramicized silicone rubber tape is a soft elastomer under normal conditions and does not affect bending after wrapping. The perfluoroalkoxy resin extrusion layer has a uniform wall thickness and can be thin-walled. The overall wire can achieve a minimum bending radius of 2D, which can adapt to the complex and tortuous wiring paths in new energy vehicles and around battery packs. It overcomes the problem that metal-sheathed cables have poor flexibility and cannot be used in narrow spaces.

[0011] Preferably, the ceramicized silicone rubber tape comprises quartz fiber gauze and silicone rubber layers disposed on both sides of the quartz fiber gauze. The silicone rubber layers comprise the following raw materials in parts by weight: 100 parts methyl vinyl silicone rubber, 50-105 parts ceramicized filler, 7-20 parts flame retardant, 5-10 parts plasticizer, 1-3 parts silane coupling agent, and 1-3 parts vulcanizing agent.

[0012] By adopting the above technical solution, using quartz fiber gauze as a skeleton and elastically combining it with the silicone rubber matrix as a buffer layer, it can absorb and disperse external mechanical impact, protect the internal core, and increase the overall strength of the wire, ensuring that the wire structure is round and stable. At the same time, the quartz fiber gauze, as a reinforcing skeleton, can also prevent high-temperature collapse, improve mechanical properties, and improve heat conduction and heat dissipation.

[0013] Preferably, the ceramicized silicone rubber tape is manufactured using the following method:

[0014] Methyl vinyl silicone rubber is plasticized at 60-80℃ for 8-12 minutes, ceramic filler, flame retardant and coupling agent are added, and it is mixed at 80-90℃ for 10-20 minutes. Plasticizer and vulcanizing agent are added, and it is mixed for 15-25 minutes. The mixture is then rolled into thin sheets, sandwiched with quartz fiber gauze, and calendered and vulcanized.

[0015] Preferably, the quartz fiber gauze undergoes the following pretreatment:

[0016] After cleaning, the quartz fiber gauze is immersed in an aqueous solution of pyrrole monomer, and then an aqueous solution of ammonium persulfate is added. The mixture is immersed at 0-5℃ for 6-10 hours. After washing and drying, it is carbonized at 500-700℃ for 1-2 hours under a nitrogen atmosphere.

[0017] By adopting the above technical solution, the surface of the quartz fiber gauze is relatively smooth and chemically inert, making it difficult for silicone rubber to wet and form chemical bonds on its surface. Pyrrole is used to polymerize in situ on the surface of the quartz fiber gauze to form polypyrrole, which becomes the interface modification layer. However, polypyrrole is prone to carbonization at high temperatures, so it is carbonized in advance to form a stable interface carbon layer that is compatible with subsequent ceramicization, reducing the possibility of decomposition and gas production. At the same time, due to volume shrinkage and gas escape during carbonization, a large number of nanoscale pores, grooves and rough structures are generated on the surface of the carbon layer. When silicone rubber comes into contact with the quartz fiber gauze, the high-viscosity rubber molecular chains can be embedded in these three-dimensional pores, forming a strong micro-mechanical interlock after curing, which enhances the peel strength between the quartz fiber gauze and the silicone rubber layer. Moreover, the carbon layer formed after polypyrrole carbonization is mainly composed of a graphitized hydrophobic carbon skeleton, which has a very strong van der Waals force with the hydrophobic groups such as methyl groups of silicone rubber, significantly improving the interface wettability and thermodynamic adhesion, and improving the adhesion between the quartz fiber gauze and the silicone rubber layer.

[0018] The increased peel strength between the quartz fiber gauze and the silicone rubber layer reduces the likelihood of fiber detachment, yarn separation, or edge tearing during wrapping, thus improving production speed and yield. Furthermore, the superior interfacial bonding allows the silicone rubber layer to effectively transfer stress to the quartz fiber gauze during repeated bending, preventing interfacial peeling. Therefore, even under stringent conditions where the wire reaches a minimum bending radius of 2D, the buffer layer maintains structural integrity, providing stable support for the high-temperature insulation layer and the insulating protective layer. This results in higher insulation reliability at the bending points after long-term use. Additionally, the improved interfacial adhesion slows down the capillary penetration of acid along the fiber-rubber interface when micro-cracks appear in the insulating protective layer, reducing the rate of inner layer corrosion.

[0019] In addition, pyrrole achieves a uniform, ultrathin carbonizable layer at the single fiber level through in-situ solution polymerization. It can be recarbonized in subsequent silicone rubber composites or in-situ service to maintain the flexibility of the quartz wire bundle and reduce the rigid binding of the fibers.

[0020] Preferably, the pretreatment of the quartz fiber gauze further includes the following steps:

[0021] Vinyltrimethoxysilane was added to an ethanol / water mixture and the pH was adjusted to 4-5 to obtain an impregnation solution.

[0022] Immerse the carbonized quartz fiber gauze in the impregnation solution for 3-5 minutes, then remove it and dry it at 80-120℃ for 15-30 minutes.

[0023] By adopting the above technical solution, vinyltrimethoxysilane is hydrolyzed to generate silanol groups, which have both reactivity and stability. When carbonized quartz fiber gauze is impregnated, the hydrolyzed silane molecules condense with oxygen-containing groups on the surface of the carbon layer through the silanol groups. The vinyl groups at the other end participate in the cross-linking reaction during the vulcanization of silicone rubber, forming a covalent bond connection between the carbon layer, silane, and silicone rubber. Therefore, silicone rubber can not only embed into the pores of the carbon layer to achieve physical anchoring, but also achieve strong adhesion through chemical bonding.

[0024] After carbonization, polypyrrole is treated to remove thermally unstable components. When the silicone rubber vulcanizing agent cable is exposed to high temperatures, it will no longer decompose and produce gas, avoiding the risk of the ceramic shell becoming porous. At 850℃, the organic part (vinyl and methoxy) of vinyltrimethoxysilane is completely decomposed, and the residue is converted into silica. It is completely fused with the silica main phase produced by the sintering of the ceramicized silicone rubber tape. The entire interface layer is finally transformed into an inorganic quartz fiber-nitrogen-doped carbon-silica-ceramic structure without any low-melting-point or gas-producing components, ensuring the density and strength of the high-temperature ceramic shell. In addition, the carbon layer and silane layer will not make the quartz fiber gauze harden or become brittle, and the cable can still meet the 2D minimum bending radius.

[0025] Preferably, the ceramicized filler comprises the following raw materials in parts by weight: 28-32 parts low melting point glass powder, 13-16 parts mica powder, 9-12 parts kaolin, and 18-22 parts fumed silica.

[0026] The flame retardant comprises aluminum hydroxide / magnesium hydroxide and zinc borate / barium metaborate in a mass ratio of 5-15:2-5;

[0027] The plasticizer is selected from hydroxyvinyl silicone oil or methyl silicone oil;

[0028] The silane coupling agent is selected from at least one of KH-550, KH560 and KH570;

[0029] The vulcanizing agent is selected from at least one of bis(2,4) and bis(2,5)-5.

[0030] Preferably, the ceramicized filler is pretreated with myristic acid solution and calcium hydroxide solution, and the specific method is as follows:

[0031] The ceramic filler was immersed in an ethanol solution of myristic acid for 2-4 hours at 40-50℃, filtered, dried, and then uniformly sprayed with a calcium hydroxide solution and dried. The molar ratio of myristic acid to calcium hydroxide was 1:2.

[0032] By adopting the above technical solution, when the myristic acid solution is soaked in ceramic filler, the carboxyl group of myristic acid forms hydrogen bonds with the hydroxyl group on the surface of the ceramic filler, and its long-chain alkyl group is regularly arranged outward. After drying, a myristic acid film is coated on the surface of the particles. After adding calcium hydroxide solution, the calcium hydroxide solution fully contacts the filler coated with myristic acid and initially generates calcium myristicate. During subsequent silicone rubber compounding or vulcanization, myristic acid is completely converted into calcium myristicate, which is firmly anchored on the surface of the ceramic filler. The stability of calcium myristicate is higher than that of myristic acid, and it is not easy to affect the adhesion between the silicone rubber layer and the perfluoroalkoxy layer at high temperature.

[0033] Furthermore, the decomposition product of calcium myristate is calcium oxide, which is itself a highly efficient flux. It can lower the melting temperature of glass powder, promote the formation of the liquid phase, and help sinter framework materials such as mica and kaolin into a denser ceramic shell. Therefore, the residue of calcium myristate is not only harmless, but can also promote the ceramicization process, completely avoiding the risk of forming pores.

[0034] The hydrophobic long-chain alkyl group of calcium myristate provides steric hindrance, preventing filler agglomeration and making it easily dispersed in silicone rubber. This improves the dispersibility of ceramic fillers in silicone rubber and acts as an internal lubricant, effectively reducing friction between fillers and between fillers and rubber molecular chains. This makes the silicone rubber layer smoother and denser, reduces the hardness of the silicone rubber tape, and increases its flexibility. When wrapped, it can conform more closely to the bending of the cable, significantly reducing rebound force and making it less prone to curling on cables with small bending radii. It also significantly reduces the overall surface energy of the silicone rubber layer, making it closer to PFA. When PFA is melt-extruded at high temperature, the wettability of the melt on the surface of the silicone rubber tape is greatly improved, allowing it to adhere more tightly to the silicone rubber tape. Moreover, during high-temperature extrusion or subsequent use, the molecular chains of PFA may generate trace amounts of free radicals due to thermal and mechanical effects, causing chain breakage. The calcium ions in calcium myristate can form ionic crosslinks with the carboxylic acid groups generated by the chain breakage of PFA, improving the peel strength between the PFA layer and the silicone rubber tape.

[0035] Preferably, the flame-retardant buffer layer has a thickness of 0.2-0.5 mm; the insulating protective layer has a thickness of 0.3-0.5 mm.

[0036] Preferably, the nickel-plated copper wire is obtained by electroplating nickel onto oxygen-free copper wire, the diameter of which is 0.12-0.39 mm; the electroplating temperature is 50-53℃, and the current density is 5-6 A / dm³. 2 The nickel plating thickness is 12-15μm; the diameter of a single strand of quartz fiber yarn is 0.2-0.5mm.

[0037] Secondly, this application provides a method for manufacturing a wire for a wire harness that can withstand temperatures up to 850°C, using the following technical solution:

[0038] A method for manufacturing a wire for a wire harness that can withstand temperatures up to 850℃ includes the following steps:

[0039] Multiple strands of nickel-plated copper wire are bundled and twisted together to obtain a conductor core;

[0040] Quartz fiber yarn is twisted and wound around the conductor core, and ceramicized silicone rubber tape is wrapped around the quartz fiber yarn. Perfluoroalkoxy resin is extruded over the ceramicized silicone rubber tape.

[0041] By adopting the above technical solution, high-purity quartz fiber yarn possesses the characteristics of low thermal conductivity and good toughness, effectively isolating heat conducted through conductors during battery thermal runaway. Ceramicized silicone rubber tape is overlapped and wrapped around the quartz fiber yarn. When the temperature reaches 500℃, the silicone rubber component decomposes to form silicon dioxide and carbides, while glass powder melts into a liquid phase. Mica and kaolin serve as the framework, and the three are sintered to form a dense, hard ceramic shell that is vibration-resistant, heat-insulating, and fire-resistant, further protecting the outer insulation layer. Even if the outer insulation layer is damaged to some extent, this shell can still maintain a certain level of insulation. In addition to serving as a flame-retardant buffer layer, the ceramicized silicone rubber tape also tightens the quartz fiber yarn, preventing the yarn from unraveling and exposing the conductor. Wrapping the ceramicized silicone rubber tape while twisting the quartz fiber yarn improves production efficiency.

[0042] Perfluoroalkoxy resin is tightly extruded onto a ceramicized silicone rubber tape. PFA has relatively high temperature resistance. After being insulated by quartz fiber yarn and ceramicized silicone rubber tape, it can maintain stable operation for ≥30 minutes under battery thermal runaway conditions. The perfluoro structure has extremely high CF bond energy and extremely high chemical inertness. Its performance is stable for a long time under sulfuric acid, hydrofluoric acid and other conditions, which can ensure the long-term reliable use of the wiring harness and wires when the battery has leakage.

[0043] The entire manufacturing process adopts the common continuous processing methods in the cable industry, such as stranding, wrapping, and extrusion. It does not use the complex dip coating, curing, and metal sheath corrugation processes of traditional high-temperature cables. The process is simple, consistent, and suitable for large-scale industrial mass production.

[0044] Preferably, the perfluoroalkoxy resin is extruded in two layers in two stages, with each single layer having a thickness of 0.15-0.25 mm.

[0045] By adopting the above technical solution, excessive thickness in a single extrusion can be prevented, which would lead to excessive internal stress and cracking after insulation bending.

[0046] Preferably, the temperatures of each zone during the extrusion of the perfluoroalkoxy resin are: 255-265℃ in zone 1 of the feeding section, 285-295℃ in zone 2 of the machine body, 295-305℃ in zone 3 of the machine body, 305-315℃ in the machine neck, and 315-325℃ in the die head.

[0047] In summary, this application has the following beneficial effects:

[0048] Because this application adopts a multi-layer composite structure of nickel-plated copper conductor, quartz fiber insulation, ceramicized silicone rubber tape buffer, and PFA acid-resistant protection, the layers work together to protect the wire, enabling it to withstand a high temperature environment of 850℃ and ensure continuous power supply for more than 30 minutes, meeting the emergency power supply and signal transmission requirements under battery thermal runaway conditions. The outermost layer of perfluoroalkoxy resin has extremely high chemical inertness due to its perfluorinated structure, allowing it to withstand long-term immersion in battery acid, eliminating the hidden danger of organosilicon coatings being incompatible with battery acid corrosion, and ensuring the long-term operational reliability of the cable under battery leakage conditions. Each layer of material has good flexibility and bendability under normal conditions. The conductor is multi-stranded, the quartz fiber is stranded and coated, and the flame-retardant buffer layer is an elastomer tape, so that the minimum bending radius of the finished wire can stably reach 2D, making it very easy to lay in the narrow and winding environment of the vehicle and battery pack. Attached Figure Description

[0049] Figure 1 This is a structural example diagram of the wire used in the 850℃ temperature-resistant wire harness in Example 1.

[0050] In the diagram: 1. High-temperature resistant conductor; 2. High-temperature resistant heat insulation layer; 3. Flame-retardant buffer layer; 4. Insulating protective layer. Detailed Implementation

[0051] The present application will be further described in detail below with reference to the embodiments.

[0052] Example

[0053] In the following examples and comparative examples, the sources of each raw material are as follows: methyl vinyl silicone rubber is selected from Hubei Xinyuhong Biotechnology, model XYH-0601, and perfluorosiloxane resin is selected from Daikin Japan, grade AP-210.

[0054] Example 1: A wire for a wire harness with a temperature resistance of 850℃, see [link / reference] Figure 1 From the inside out, it includes a high-temperature resistant conductor 1, a high-temperature resistant heat insulation layer 2, a flame-retardant buffer layer 3, and an insulating protective layer 4.

[0055] High-temperature resistant conductor 1 is a conductor core made of multiple nickel-plated copper wires twisted together, with a nominal cross-sectional area of ​​0.3 mm². 2 Nickel-plated copper wire is made from oxygen-free copper wire through electroplating with nickel. The oxygen-free copper wire has 19 individual wires, a diameter of 0.16 mm, an electroplating temperature of 53℃, and a current density of 6 A / dm³. 2 The nickel plating thickness is 12-15μm.

[0056] The high-temperature resistant insulation layer 2 is made of quartz fiber yarn twisted and wound on the high-temperature resistant conductor 1. The number of yarns / yarn diameter is 12 / 0.2mm, and the purity of the quartz fiber yarn is SiO2≥99.95%. It tightly wraps the conductor core and the conductor core is not exposed.

[0057] The flame-retardant buffer layer 3 is a ceramicized silicone rubber tape wrapped around quartz fiber yarn with a thickness of 0.2 mm. The ceramicized silicone rubber tape includes quartz fiber gauze with a thickness of 0.1 mm and silicone rubber layers set on both sides of the quartz fiber gauze. The raw material usage of the silicone rubber layer is as follows: 100 kg methyl vinyl silicone rubber, 75 kg ceramicized filler, 10 kg flame retardant, 8 kg plasticizer hydroxyl silicone oil, 2 kg silane coupling agent KH-550, 2 kg vulcanizing agent DCP. The ceramicized filler includes 30 kg low melting point glass powder, 15 kg mica powder, 10 kg kaolin and 20 kg fumed silica. The flame retardant includes aluminum hydroxide and zinc borate in a mass ratio of 7:3.

[0058] The method for manufacturing ceramicized silicone rubber tape is as follows: Methyl vinyl silicone rubber is plasticized at 80°C for 10 minutes, ceramicized filler, flame retardant, and coupling agent are added, and after mixing at 80°C for 10 minutes, plasticizer and vulcanizing agent are added and mixed for 20 minutes. After thinning and rolling, the tape is placed for 24 hours and then sandwiched with quartz fiber gauze. It is then calendered and vulcanized at 150°C for 20 minutes. The temperature is then raised to 200°C and vulcanized for another 4 hours.

[0059] The insulating protective layer 4 is a perfluoroalkoxy layer extruded onto a ceramicized silicone rubber tape, with a nominal thickness of 0.3 mm.

[0060] The method for manufacturing the above-mentioned 850℃ temperature-resistant cable for wire harnesses includes the following steps:

[0061] S1. The nickel-plated copper wire is bundled and twisted to form a conductor core. The direction of the bundle and twisting of the nickel-plated copper wire is left-handed, and the twisting pitch ratio is 10-15 times.

[0062] S2. Twist and wind the quartz fiber yarn onto the conductor core obtained in S1. The twisting direction of the quartz fiber yarn is to the left, and the twisting pitch ratio is 10-15 times.

[0063] S3. Overlap the ceramicized silicone rubber tape onto the quartz fiber yarn obtained in S1, with an overlap rate of ≥25% and the wrapping direction is to the right.

[0064] S4. The perfluorosiloxane resin is dried at 120℃ for 6 hours, and then extruded onto the ceramicized silicone rubber obtained in S3 to produce wire harnesses with a temperature resistance of 850℃. The perfluorosiloxane resin is extruded in two stages, with a single layer thickness of 0.15mm to prevent excessive internal stress and bending cracking caused by excessive extrusion thickness. The body temperature zones during extrusion are as follows: feeding section 1 zone 260℃, body 2 zone 290℃, body 3 zone 300℃, neck 310℃, and head 320℃. The body and head are heated by thermocouples, the body is cooled by blower cooling, and the wire core is cooled by segmented water cooling: slow cooling zone 65℃, intermediate cooling zone 40℃, and final cooling zone room temperature water.

[0065] Example 2: A wire for a wire harness with a temperature resistance of 850℃, see [link / reference] Figure 1 From the inside out, it includes a high-temperature resistant conductor 1, a high-temperature resistant heat insulation layer 2, a flame-retardant buffer layer 3, and an insulating protective layer 4.

[0066] High-temperature resistant conductor 1 is a conductor core made of nickel-plated copper wire stranded together, with a nominal cross-sectional area of ​​0.3 mm². 2 Nickel-plated copper wire is made from oxygen-free copper wire through electroplating with nickel. The oxygen-free copper wire has 19 individual wires, a diameter of 0.16 mm, an electroplating temperature of 50℃, and a current density of 5 A / dm³. 2 The nickel plating thickness is 12-15μm.

[0067] The high-temperature resistant insulation layer 2 is made of quartz fiber yarn twisted and wound on the high-temperature resistant conductor 1. The number of yarns / yarn diameter is 12 / 0.2mm, and the purity of the quartz fiber yarn is SiO2≥99.95%. It tightly wraps the conductor core and the conductor core is not exposed.

[0068] The flame-retardant buffer layer 3 is a ceramicized silicone rubber tape wrapped around quartz fiber yarn with a thickness of 0.3 mm. The ceramicized silicone rubber tape includes quartz fiber gauze with a thickness of 0.1 mm and silicone rubber layers on both sides of the quartz fiber gauze. The raw material usage of the silicone rubber layer is as follows: 100 kg methyl vinyl silicone rubber, 75 kg ceramicized filler, 10 kg flame retardant, 10 kg plasticizer hydroxyl silicone oil, 3 kg silane coupling agent KH-550, 3 kg vulcanizing agent DCP. The ceramicized filler includes 40 kg low melting point glass powder, 10 kg mica powder, 15 kg kaolin and 10 kg fumed silica. The flame retardant includes magnesium hydroxide and barium metaborate in a mass ratio of 5:5.

[0069] The method for manufacturing ceramicized silicone rubber tape is as follows: Methyl vinyl silicone rubber is plasticized at 60°C for 12 minutes, ceramicized filler, flame retardant, and coupling agent are added, and after mixing at 90°C for 10 minutes, plasticizer and vulcanizing agent are added. After mixing for 25 minutes, the tape is rolled into a thin sheet and left to stand for 24 hours. Then, it is sandwiched with quartz fiber gauze, calendered, and vulcanized at 150°C for 20 minutes. The temperature is then raised to 200°C and vulcanized for another 4 hours.

[0070] The insulating protective layer 4 is a perfluoroalkoxy layer extruded onto a ceramicized silicone rubber tape, with a nominal thickness of 0.5 mm.

[0071] The method for manufacturing the above-mentioned 850℃ temperature-resistant cable for wire harnesses includes the following steps:

[0072] S1. The nickel-plated copper wire is bundled and twisted to form a conductor core. The direction of the bundle and twisting of the nickel-plated copper wire is left-handed, and the twisting pitch ratio is 10-15 times.

[0073] S2. Twist and wind the quartz fiber yarn onto the conductor core obtained in S1. The twisting direction of the quartz fiber yarn is to the left, and the twisting pitch ratio is 10-15 times.

[0074] S3. Overlap the ceramicized silicone rubber tape onto the quartz fiber yarn obtained in S1, with an overlap rate of ≥25% and the wrapping direction is to the right.

[0075] S4. The perfluorosiloxane resin is dried at 130℃ for 6 hours, and then extruded onto the ceramicized silicone rubber obtained in S3 to produce wire harnesses with a temperature resistance of 850℃. The perfluorosiloxane resin is extruded in two stages, with a single layer thickness of 0.25mm to prevent excessive internal stress and bending cracking caused by excessive extrusion thickness. The body temperature zones during extrusion are as follows: feeding section 1 zone 265℃, body 2 zone 295℃, body 3 zone 305℃, neck 315℃, and head 325℃. The body and head are heated by thermocouples, the body is cooled by blower cooling, and the wire core is cooled by segmented water cooling: slow cooling zone 75℃, intermediate cooling zone 50℃, and final cooling zone room temperature water.

[0076] Example 3: A wire for a wire harness with a temperature resistance of 850℃, differing from Example 1 in that the quartz fiber gauze undergoes the following pretreatment before being calendered and vulcanized with a silicone rubber layer:

[0077] (1) After cleaning and drying the quartz fiber gauze with acetone, it was soaked in pyrrole monomer aqueous solution, and ammonium persulfate aqueous solution was added. It was soaked at 5°C for 10 hours. The quartz fiber gauze was washed twice with deionized water and anhydrous ethanol, and then dried at 60°C for 24 hours. The concentration of pyrrole monomer aqueous solution was 15.2 g / L, and the concentration of ammonium persulfate aqueous solution was 20 g / L.

[0078] (2) The quartz fiber gauze obtained in step (1) is heated to 300°C at 10°C / min under a nitrogen atmosphere, kept at the temperature for 30 min, and then heated to 700°C for 1 h.

[0079] Example 4: A wire for a wire harness with a temperature resistance of 850℃, differing from Example 1 in that the quartz fiber gauze undergoes the following pretreatment before being calendered and vulcanized with a silicone rubber layer:

[0080] Quartz fiber gauze was cleaned with acetone, dried, and then immersed in an aqueous solution of pyrrole monomer. An aqueous solution of ammonium persulfate was added, and the mixture was immersed at 5°C for 10 hours. The quartz fiber gauze was then washed twice with deionized water and anhydrous ethanol, and dried at 60°C for 24 hours. The concentration of the aqueous solution of pyrrole monomer was 15.2 g / L, and the concentration of the aqueous solution of ammonium persulfate was 20 g / L.

[0081] Example 5: A wire for a wire harness with a temperature resistance of 850℃, differing from Example 1 in that the quartz fiber gauze undergoes the following pretreatment before being calendered and vulcanized with a silicone rubber layer:

[0082] (1) After cleaning and drying the quartz fiber gauze with acetone, it was soaked in pyrrole monomer aqueous solution, and ammonium persulfate aqueous solution was added. It was soaked at 5°C for 10 hours. The quartz fiber gauze was washed twice with deionized water and anhydrous ethanol, and then dried at 60°C for 24 hours. The concentration of pyrrole monomer aqueous solution was 15.2 g / L, and the concentration of ammonium persulfate aqueous solution was 20 g / L.

[0083] (2) The quartz fiber gauze obtained in step (1) is heated to 300°C at 10°C / min under a nitrogen atmosphere, kept at the temperature for 30 min, and then heated to 700°C for 1 h.

[0084] (3) Add vinyltrimethoxysilane to a mixed solution of ethanol / water (volume ratio of 95:5), adjust the pH to 5 with acetic acid to partially hydrolyze it, and obtain an impregnation solution with a concentration of 3wt%.

[0085] (4) Immerse the carbonized quartz fiber gauze obtained in step (2) in the impregnation solution for 5 minutes, take it out and air dry it, and dry it at 80°C for 30 minutes.

[0086] Example 6: A wire for a wire harness with a temperature resistance of 850℃, differing from Example 1 in that the ceramicized filler undergoes the following pretreatment:

[0087] The ceramicized filler was impregnated in an ethanol solution of myristic acid with a concentration of 1 g / ml, the mass ratio of the ceramicized filler to the ethanol solution of myristic acid being 1:2. The impregnation was carried out at 50°C for 4 h, filtered, dried at 80°C for 2 h, and then uniformly sprayed with a calcium hydroxide solution with a concentration of 2 g / ml. The solution was then dried at 80°C for 60 min. The molar ratio of myristic acid to calcium hydroxide was 1:2, and the amount of myristic acid used was 1 wt% of the amount of ceramicized filler.

[0088] Example 7: A wire for a wire harness with a temperature resistance of 850℃, differing from Example 1 in that the ceramicized filler undergoes the following pretreatment:

[0089] The ceramicized filler was impregnated in an ethanol solution of myristic acid with a concentration of 1 g / ml, the mass ratio of the ceramicized filler to the ethanol solution of myristic acid being 1:2. The impregnation was carried out at 50°C for 4 hours, filtered, and dried at 80°C for 2 hours.

[0090] Example 8: A wire for a wire harness with a temperature resistance of 850℃, differing from Example 1 in that both the quartz fiber gauze and the ceramicized filler undergo certain pretreatment, wherein the ceramicized filler undergoes the following pretreatment:

[0091] The ceramicized filler was impregnated in an ethanol solution of myristic acid at a concentration of 1 g / ml, with a mass ratio of 1 g / ml to 2 g / ml. The impregnation was carried out at 50°C for 4 hours, filtered, and dried at 80°C for 2 hours. Then, a calcium hydroxide solution at a concentration of 2 g / ml was uniformly sprayed onto the surface and dried at 80°C for 60 minutes. The molar ratio of myristic acid to calcium hydroxide was 1:2, and the amount of myristic acid used was 1 wt% of the ceramicized filler.

[0092] Quartz fiber gauze undergoes the following pretreatment before being calendered and vulcanized with a silicone rubber layer:

[0093] (1) After cleaning and drying the quartz fiber gauze with acetone, it was soaked in pyrrole monomer aqueous solution, and ammonium persulfate aqueous solution was added. It was soaked at 5°C for 10 hours. The quartz fiber gauze was washed twice with deionized water and anhydrous ethanol, and then dried at 60°C for 24 hours. The concentration of pyrrole monomer aqueous solution was 15.2 g / L, and the concentration of ammonium persulfate aqueous solution was 20 g / L.

[0094] (2) The quartz fiber gauze obtained in step (1) is heated to 300°C at 10°C / min under a nitrogen atmosphere, kept at the temperature for 30 min, and then heated to 700°C for 1 h.

[0095] (3) Add vinyltrimethoxysilane to a mixed solution of ethanol / water (volume ratio of 95:5), adjust the pH to 5 with acetic acid to partially hydrolyze it, and obtain an impregnation solution with a concentration of 3wt%.

[0096] (4) Immerse the carbonized quartz fiber gauze obtained in step (2) in the impregnation solution for 5 minutes, take it out and air dry it, and dry it at 80°C for 30 minutes.

[0097] Comparative Example

[0098] Comparative Example 1: A wire for a harness with a temperature resistance of 850℃, which differs from Example 1 in that it does not have an insulating protective layer 4. From the inside out, it includes a high-temperature resistant conductor 1, a high-temperature resistant heat insulation layer 2, and a flame-retardant buffer layer 3. The preparation method is the same as that of Example 1.

[0099] Comparative Example 2: A wire for a wire harness with a temperature resistance of 850℃, which differs from Example 1 in that it does not have a flame-retardant buffer layer 3. From the inside out, it includes a high-temperature resistant conductor 1, a high-temperature resistant heat insulation layer 2, and an insulating protective layer 4. The insulating protective layer 4 is extruded onto the high-temperature resistant heat insulation layer 2. The process parameters are the same as those in Example 1.

[0100] Comparative Example 3: A wire for a wire harness with a temperature resistance of 850℃, which differs from Example 1 in that it does not have a high-temperature heat insulation layer 2. From the inside out, it includes a high-temperature conductor 1, a flame-retardant buffer layer 3 and an insulating protective layer 4. The flame-retardant buffer layer 3 is made by wrapping ceramicized silicone rubber tape around the high-temperature conductor 1. The other process parameters are the same as those in Example 1.

[0101] Performance testing

[0102] The wires for the 850°C wire harness were prepared according to the methods in the examples and comparative examples. The performance was tested according to the following methods, and the test results are recorded in Table 1.

[0103] 1. Minimum bending radius: Refer to GB / T9330-2020 "Plastic Insulated Control Cables" standard, take 3 1-meter long cables and bend them 360° in one direction with different core diameters. Observe whether cracks appear on the surface and record the minimum bending radius (a multiple of the cable outer diameter (D)) without cracking. A lower minimum bending radius indicates that the cable is flexible and suitable for confined spaces or scenarios that require frequent bending.

[0104] 2. Temperature change resistance test: Take cable samples of the same length and conduct a temperature change resistance test in accordance with the requirements of QC / T29016 "Technical Conditions for Automotive Wiring Harnesses". The temperature range is -45℃ to 260℃, the exposure time is 2h, the temperature change rate is (5±1)K / min, and a standard voltage of 60V / DC is applied. This is one cycle. Repeat the cycle until an insulation short circuit, short circuit or miscircuit occurs.

[0105] 3. Withstand voltage test: The test shall be conducted at 3kV / 1min in accordance with GB / T3048.8-2007 "Test methods for electrical properties of wires and cables - Part 8: AC voltage test".

[0106] 4. Duration of energization under thermal runaway at 850℃: Refer to GB / T19216.21 "Line integrity test of cables or optical fibers under flame conditions in fire environments - Part 21: Test methods and requirements - Cables with rated voltage of 0.6 / 1kV and below", with the flame condition changed to 850℃. The specific method is as follows:

[0107] (1) Test apparatus: a tube furnace or muffle furnace with a furnace chamber length of at least 0.5 meters and a hole for wires to pass through; (2) Sample preparation: take a 1-meter-long finished wire and strip the conductors of sufficient length at both ends for connecting the test circuit; (3) connect the conductor of the test circuit wire in series with a low-voltage current and an indicator light or current ratio to determine whether the circuit is continuously energized; (4) Test procedure: heat the furnace to 850°C and stabilize it, quickly place the middle section of the wire sample (about 0.5 meters) horizontally into the constant temperature zone of the furnace chamber, leave both ends outside the furnace and fix them, immediately close the power supply of the test circuit, start timing, and record the time from the high temperature of 850°C until the wire short circuit, short circuit or insulation resistance drops sharply.

[0108] 5. Battery acid resistance: (1) Sample preparation: Take 3 sections of finished wire, each about 0.5 meters long; (2) Test medium: 25% sulfuric acid + 75% deionized water (volume ratio) to simulate battery leakage; (3) Immersion method: Bend the sample into a U-shape and immerse it completely in the acid solution, leaving only the conductors at both ends exposed about 5 cm above the liquid surface. Seal the container and keep the immersion temperature at 60℃; (4) Test cycle: Immersion for 1000 hours; (5) Detect its insulation resistance retention rate.

[0109] Table 1

[0110]

[0111] Based on the test data in Table 1 and the raw material usage in Examples 1 and 2, it can be seen that the wire harness prepared in this application can maintain power supply time of ≥30min under battery thermal runaway conditions. At the same time, it can also solve the problem that conventional high-temperature cables are easily corroded, aged, and cracked in the acidic environment of batteries. In addition, it has good high-temperature resistance and good protection and heat insulation capabilities.

[0112] In Example 3, pyrrole monomers were self-polymerized on quartz fiber gauze to form polypyrrole, which was then carbonized. Compared with Example 1, the wire harness obtained in Example 3 has better high-temperature resistance and longer energization time under thermal runaway.

[0113] In Example 4, only pyrrole monomer was used for self-polymerization on quartz fiber gauze without carbonization. Compared with Examples 1 and 3, its heat resistance and corrosion resistance were slightly reduced. This indicates that carbonizing polypyrrole in advance can prevent it from decomposing under thermal runaway and affecting the wrapping ability of silicone tape, thereby weakening the high temperature resistance of the wire. Carbonization can avoid the risk of high temperature resistance.

[0114] Compared with Example 1, Example 5 uses pyrrole monomer to self-polymerize on quartz fiber gauze and then carbonizes it. Finally, it is impregnated with vinyltrimethoxysilane solution. The data in Table 1 shows that compared with Example 3, the wire prepared in Example 5 has enhanced high temperature resistance, increased energization time under thermal runaway, and improved corrosion resistance. This indicates that vinyltrimethoxysilane can improve the bonding between the carbon layer and silicone rubber, enhance interfacial adhesion, and improve the tightness of the wrapping. At the same time, after its decomposition, it fuses with the silica produced by the sintering of silicone rubber tape, improving the density and strength of the high-temperature ceramic shell and enhancing its heat resistance.

[0115] Compared with Example 1, Example 6 uses myristic acid and calcium hydroxide to pretreat the ceramic filler. As can be seen from the data in Table 1, the wires made in Example 6 have enhanced temperature resistance and improved acid corrosion resistance.

[0116] Compared with Example 1, Example 7 only used myristic acid to treat the ceramic filler. It can be seen that the wire produced by Example 7 has a lower temperature resistance and a weaker corrosion resistance compared with Example 6. This shows that the use of myristic acid alone is prone to high-temperature decomposition, which has an adverse effect on the interlayer bonding.

[0117] In Example 8, not only were myristic acid and calcium hydroxide used to pretreat the ceramicized filler, but polypyrrole was also used to pretreat the quartz fiber gauze. It can be seen that the wires made in Example 8 have enhanced high temperature resistance and improved acid corrosion resistance compared with those in Example 5 and Example 6.

[0118] In Comparative Example 1, no insulating protective layer 4 was provided. Compared with Example 1, it can be seen that the insulation resistance retention rate of the manufactured wire decreased significantly under acid corrosion, the acid corrosion resistance was weakened, and the heat resistance also decreased to a certain extent.

[0119] Comparative Example 2 did not have a flame-retardant buffer layer 3, and Comparative Example 3 did not have a high-temperature resistant insulation layer 2. It can be seen that the wires made in Comparative Example 2 and Comparative Example 3 had a shorter continuous power-on time under thermal runaway and a decrease in heat resistance.

[0120] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A wire for a wire harness with a temperature resistance of 850℃, characterized in that, From the inside out, it includes a high-temperature resistant conductor (1), a high-temperature resistant heat insulation layer (2), a flame-retardant buffer layer (3), and an insulating protective layer (4); the high-temperature resistant conductor (1) is a conductor core made of at least one strand of nickel-plated copper wire twisted together; the high-temperature resistant heat insulation layer (2) is a quartz fiber yarn twisted and wrapped around the high-temperature resistant conductor (1); the flame-retardant buffer layer (3) is a ceramicized silicone rubber tape wrapped around the high-temperature resistant heat insulation layer (2); and the insulating protective layer (4) is a perfluoroalkoxy resin layer extruded around the flame-retardant buffer layer (3).

2. The wire for a wire harness with a temperature resistance of 850℃ according to claim 1, characterized in that: The ceramicized silicone rubber tape includes quartz fiber gauze and silicone rubber layers disposed on both sides of the quartz fiber gauze. The silicone rubber layers include the following raw materials in parts by weight: 100 parts methyl vinyl silicone rubber, 50-105 parts ceramicized filler, 7-20 parts flame retardant, 5-10 parts plasticizer, 1-3 parts silane coupling agent, and 1-3 parts vulcanizing agent.

3. The wire for a wire harness with a temperature resistance of 850℃ according to claim 2, characterized in that: The quartz fiber gauze undergoes the following pretreatment: After cleaning, the quartz fiber gauze is immersed in an aqueous solution of pyrrole monomer, and then an aqueous solution of ammonium persulfate is added. The mixture is immersed at 0-5℃ for 6-10 hours. After washing and drying, it is carbonized at 500-700℃ for 1-2 hours under a nitrogen atmosphere.

4. The wire for a wire harness with a temperature resistance of 850℃ according to claim 2, characterized in that: The pretreatment of the quartz fiber gauze also includes the following steps: Vinyltrimethoxysilane was added to an ethanol / water mixture and the pH was adjusted to 4-5 to obtain an impregnation solution. Immerse the carbonized quartz fiber gauze in the impregnation solution for 3-5 minutes, then remove it and dry it at 80-120℃ for 15-30 minutes.

5. The wire for a wire harness with a temperature resistance of 850℃ according to claim 2, characterized in that: The ceramicized filler comprises the following raw materials in parts by weight: 28-32 parts low melting point glass powder, 13-16 parts mica powder, 9-12 parts kaolin, and 18-22 parts fumed silica. The flame retardant comprises aluminum hydroxide / magnesium hydroxide and zinc borate / barium metaborate in a mass ratio of 5-15:2-5; The plasticizer is selected from hydroxyvinyl silicone oil or methyl silicone oil; The silane coupling agent is selected from at least one of KH-550, KH560 and KH570; The vulcanizing agent is selected from at least one of bis(2,4) and bis(2,5)-5.

6. The wire for a wire harness with a temperature resistance of 850℃ according to claim 5, characterized in that: The ceramicized filler is pretreated with myristic acid solution and calcium hydroxide solution, as follows: The ceramic filler was immersed in an ethanol solution of myristic acid for 2-4 hours at 40-50℃, filtered, dried, and then uniformly sprayed with a calcium hydroxide solution and dried. The molar ratio of myristic acid to calcium hydroxide was 1:

2.

7. The wire for a wire harness with a temperature resistance of 850℃ according to claim 1, characterized in that: The flame-retardant buffer layer (3) has a thickness of 0.2-0.5 mm; the insulating protective layer (4) has a thickness of 0.3-0.5 mm.

8. The method for preparing a wire harness with a temperature resistance of 850°C according to any one of claims 1-7, characterized in that, Includes the following steps: Multiple strands of nickel-plated copper wire are bundled and twisted together to obtain a conductor core; Quartz fiber yarn is twisted and wound around the conductor core, and ceramicized silicone rubber tape is wrapped around the quartz fiber yarn. Perfluoroalkoxy resin is extruded over the ceramicized silicone rubber tape.

9. The method for preparing a wire for a wire harness with a temperature resistance of 850℃ according to claim 8, characterized in that, The perfluoroalkoxy resin is extruded in two layers in two stages, with each single layer having a thickness of 0.15-0.25 mm.

10. The method for preparing a wire harness with a temperature resistance of 850℃ according to claim 8, characterized in that, The temperatures of each zone during the extrusion of the perfluoroalkoxy resin are as follows: Zone 1 of the feeding section 255-265℃, Zone 2 of the machine body 285-295℃, Zone 3 of the machine body 295-305℃, Neck 305-315℃, and Head 315-325℃.

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