Engine wire harness with good shielding property and preparation method thereof

Abstract

The invention relates to an engine wire harness with good shielding performance and a preparation method thereof, and belongs to the technical field of new energy automobiles. The compatilizer is prepared, the compatilizer is a polyphenyl ether-polyethylene grafted copolymer, a polyphenyl ether chain segment in the molecular structure is compatible with polyphenyl ether, a polyethylene chain segment in the molecular structure is compatible with high-density polyethylene, the structure can significantly reduce the interfacial tension between two phases of polyphenyl ether / high-density polyethylene, and the interfacial adhesive force is greatly enhanced; compared with the prior art, phase separation and interface stripping are effectively inhibited, the mechanical property of the material can be effectively improved, in addition, the compatilizer does not need to introduce a new resin component, the potential influence of external components on the matrix performance is avoided, and the inherent performance of polyphenyl ether and high-density polyethylene matrix resin can be better reserved.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy vehicles, and in particular relates to an engine wiring harness with good shielding properties and a preparation method thereof. Background Art

[0002] In the high-voltage electrical architecture of new energy vehicles, the engine wiring harness is the core carrier of power transmission, and its reliability is directly related to the power performance and safe operation of the whole vehicle. High-density polyethylene has excellent mechanical properties, oil resistance, and low cost, so it is widely used in the outer sheath material of the engine harness. However, as the power density of new energy drive systems continues to rise, the thermal environment in the motor compartment is becoming increasingly harsh, and the local temperature has exceeded 140°C, far exceeding the long-term use temperature of high-density polyethylene. Under long-term high-temperature conditions, the molecular chains of the polymer will undergo oxidative degradation, causing the sheath to soften, creep, and even melt, accompanied by thermal aging embrittlement, destroying the integrity of the outer sheath, and greatly affecting the shielding performance of the engine harness. In order to solve the above technical defects, the present invention provides an engine wiring harness with good shielding properties and a preparation method thereof. Summary of the Invention

[0003] The object of the present invention is to provide an engine wiring harness with good shielding properties and a preparation method thereof, so as to solve the problems mentioned in the above background technology.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing an engine wiring harness with good shielding properties comprises the following steps: The first step is to mix 4,4'-diaminodiphenyl disulfide, triethylamine, and dichloromethane in a reaction flask equipped with a condenser, a thermometer, and a magnetic stirring rotor, and then add carbon disulfide dropwise to the reaction flask after turning on the magnetic stirring. The addition time is 30 to 60 minutes. After the addition is completed, the reaction is continued at room temperature for 2 to 3 hours. The reaction flask is then cooled with an ice-water bath, and a dichloromethane solution of tert-butyl carbonate diethyl phosphoric anhydride is added dropwise to the reaction flask. The addition time is 15 to 25 minutes. After the addition is completed, the ice-water bath is removed and the reaction is continued for 3 to 4 hours. After the reaction is completed, the pH of the system is adjusted to 5 to 7 with dilute hydrochloric acid, and then the organic phase is separated. The organic phase is rotary evaporated to remove the solvent and then eluted by silica gel column chromatography to obtain a modifier; The modifier is obtained by utilizing the rearrangement reaction of the amino group of 4,4'-diaminodiphenyl disulfide and carbon disulfide under the action of the desulfurization reagent tert-butyl carbonate diethyl phosphoric anhydride.

[0005] Step 2: Mix polyphenylene ether and toluene in a reaction flask equipped with a condenser, a thermometer, and a magnetic stirring rotor, raise the system temperature to 90-110°C and stir until completely dissolved, then add an initiator to the reaction flask, and continue to react at a temperature of 90-110°C for 1.5 hours, then add a modifier to the reaction flask, and continue to react at a temperature of 90-110°C for 40-60 minutes. After the reaction is completed, the reaction solution is cooled to room temperature and filtered, and the obtained solid is washed with anhydrous ethanol and dried to obtain polyphenylene ether with disulfide bonds; An initiator is used to oxidatively cleave polyphenylene ether to obtain low molecular weight polyphenylene ether, and then the hydroxyl group in the low molecular weight polyphenylene ether reacts with the isothiocyanate group in the modifier to obtain polyphenylene ether with disulfide bonds.

[0006] Step 3: Pre-irradiate the high-density polyethylene powder, and add the irradiated high-density polyethylene powder, polyphenylene ether with disulfide bonds, initiator, and toluene into a reaction bottle equipped with a magnetic stirring rotor under nitrogen protection. After turning on the magnetic stirring, react at a temperature of 90-120° C. for 8-24 hours. After the reaction is completed, cool to room temperature and filter out the solid, wash it with anhydrous ethanol and deionized water in sequence, and then dry it to obtain a compatibilizer. After irradiation, the hydroxyl content in the structure of high-density polyethylene powder is greatly increased. The polyphenylene ether with disulfide bonds breaks the disulfide bonds under the action of the initiator to produce sulfur free radicals that attack the double bonds in the structure of the irradiated high-density polyethylene powder, obtaining a compatibilizer that can be used to improve the compatibility of polyphenylene ether and polyethylene.

[0007] Step 4: oxidizing the conductive filler to obtain a modified conductive filler; Oxidation can effectively increase the number of oxygen-containing groups on the surface of conductive fillers.

[0008] The fifth step is to dry and mix the modified polyphenylene ether, compatibilizer, high-density polyethylene, modified conductive filler, antioxidant, and flame retardant, add them into a nitrogen-protected twin-screw extruder for melt extrusion, and then cool and pull them and sleeve them on the outer surface of the fiber core to obtain an engine wiring harness with good shielding properties.

[0009] As a further preference of the present invention, the initiator in the second step is at least one of benzoyl peroxide and dicumyl peroxide.

[0010] As a further preferred embodiment of the present invention, the initiator in the third step is at least one of tert-butyl peroxy-2-ethylhexanoate and tert-butyl peroxycarbonate-2-ethylhexyl ester.

[0011] As a further preferred embodiment of the present invention, the conductive filler in the fourth step is conductive carbon black.

[0012] As a further preferred embodiment of the present invention, the antioxidant in the fifth step is at least one of antioxidant 1010, antioxidant 1035, sodium hypophosphite, and antioxidant 168.

[0013] As a further preference of the present invention, the flame retardant in the fifth step is a phosphate flame retardant, including at least one of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide (OPOPB).

[0014] As a further preferred embodiment of the present invention, in the first step, the molar ratio of 4,4′-diaminodiphenyl disulfide, carbon disulfide, and tert-butyl carbonate diethyl phosphoric anhydride is 1:2.1-2.3:2.1-2.3.

[0015] As a further preferred embodiment of the present invention, in the second step, the mass ratio of polyphenylene ether, initiator, and modifier is 20:0.8-1.2:2-3.

[0016] As a further preferred embodiment of the present invention, in the third step, the mass ratio of polyethylene, polyphenylene ether with disulfide bonds, and initiator is 15-25:15:1.2-1.6.

[0017] As a further preferred embodiment of the present invention, the modified polyphenylene ether is a blend of polyphenylene ether and polystyrene, and the mass fraction of the polyphenylene ether in the modified polyphenylene ether is 50-60%.

[0018] As a further preference of the present invention, in the fifth step, the mass ratio of modified polyphenylene ether, compatibilizer, high-density polyethylene, modified conductive filler, antioxidant and flame retardant is 240-280:20:120-160:50-60:2.5-3.5:10-20.

[0019] As a further preferred embodiment of the present invention, the temperature condition of the melt extrusion in the fifth step is 245-255°C.

[0020] An engine wiring harness with good shielding performance is prepared by any of the above preparation steps.

[0021] The present invention has at least one of the following beneficial effects: The compatibilizer of the present invention is a polyphenylene ether-polyethylene graft copolymer. The polyphenylene ether segments in this molecular structure are compatible with the polyphenylene ether phase, and the polyethylene segments are compatible with the high-density polyethylene phase. This structure can significantly reduce the interfacial tension between the polyphenylene ether / high-density polyethylene phases, greatly enhance interfacial adhesion, and effectively inhibit phase separation and interfacial debonding. During the melt blending process, the compatibilizer stabilizes the dispersed polyphenylene ether droplets by reducing interfacial energy, effectively preventing their coarsening and coalescence, and promoting a significant reduction in the size of the polyphenylene ether phase and uniform distribution. Ultimately, a fine, stable phase morphology is formed. This optimized microstructure can effectively improve the mechanical properties (such as tensile strength and impact toughness) of the material. Furthermore, the compatibilizer does not require the introduction of new resin components, avoiding the potential impact of foreign components on matrix properties and better preserving the inherent properties of the polyphenylene ether and high-density polyethylene matrix resins.

[0022] The present invention uses modified polyphenylene ether and high-density polyethylene to blend to obtain a composite material. A large number of ether bonds and thioether structures exist in the composite material structure, which can not only serve as hydrogen bond acceptors to form hydrogen bonds with carboxyl groups in the oxidized conductive filler, but also significantly improve the dispersibility of the conductive filler in the outer sheath, and improve the interfacial bonding ability between the conductive filler and the composite material (mainly the polyphenylene ether phase) in the outer sheath, and promote the enrichment of the conductive network at the interface of the polyphenylene ether phase, so that a high-efficiency, low-percolation threshold conductive network can be constructed with a smaller addition amount.

[0023] The present invention uses polyphenylene ether with excellent heat resistance and intrinsic flame retardancy to compound with high-density polyethylene, which significantly overcomes the shortcomings of single polyolefin materials in heat resistance and flame retardancy. Polyphenylene ether itself has a high glass transition temperature, which can give the outer sheath good high-temperature dimensional stability, inhibit the aging of the outer sheath in a high-temperature use environment, and effectively avoid the embrittlement and cracking of the outer sheath that affect the integrity of the outer sheath; at the same time, the polyphenylene ether molecular structure contains an inherent flame retardant structure and additionally introduced sulfur-containing groups, and can also produce a synergistic effect with phosphorus-based flame retardants, catalyze the formation of phosphorus oxygen free radicals, promote carbonization during combustion, and isolate heat and oxygen. By compounding with HDPE, not only the overall heat resistance level and the upper limit of the use temperature of the outer sheath are significantly improved, but also the amount of flame retardant added can be effectively reduced, thereby effectively maintaining the toughness of the material and improving the processing performance of the material. DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solutions of the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection requested by this application.

[0025] The sources of all raw materials in the present invention are not particularly limited and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0026] Example 1:

[0027] A method for preparing an engine wiring harness with good shielding properties comprises the following steps: The first step is to mix 20mmol 4,4'-diaminodiphenyl disulfide, 60mmol triethylamine, and 50mL dichloromethane in a reaction flask equipped with a condenser, a thermometer, and a magnetic stirring rotor. After turning on the magnetic stirring, 42mmol carbon disulfide is added dropwise to the reaction flask for 30min. After the addition is complete, the reaction is continued at room temperature for 3h. The reaction flask is then cooled with an ice-water bath, and a solution prepared by adding 42mmol tert-butyl carbonate diethyl phosphoric anhydride and 25mL dichloromethane is added dropwise to the reaction flask for 15min. After the addition is complete, the ice-water bath is removed and the reaction is continued for 4h. After the reaction is completed, the pH of the system is adjusted to 5 using dilute hydrochloric acid, and then the organic phase is separated. The organic phase is evaporated to remove the solvent and then eluted by silica gel column chromatography to obtain a modifier; Step 2: 20 g of polyphenylene ether and 60 g of toluene were mixed in a reaction flask equipped with a condenser, a thermometer, and a magnetic stirring rotor. The system temperature was raised to 90°C and stirred until completely dissolved. 0.8 g of benzoyl peroxide was then added to the reaction flask, and the reaction was continued at 90°C for 1.5 h. 2 g of a modifier was then added to the reaction flask, and the reaction was continued at 90°C for 60 min. After the reaction was completed, the reaction solution was cooled to room temperature and filtered. The obtained solid was washed with anhydrous ethanol and dried to obtain polyphenylene ether with disulfide bonds. The third step is to use an electron accelerator as an irradiation source to pre-irradiate the high-density polyethylene powder with beta rays. The irradiation conditions are an acceleration voltage of 5 MeV and a current of 12 mA. Under nitrogen protection, 15 g of irradiated high-density polyethylene powder, 15 g of polyphenylene ether with a disulfide bond, 1.2 g of tert-butyl peroxy-2-ethylhexanoate, and 80 mL of toluene are added to a reaction bottle equipped with a magnetic stirring rotor. After turning on the magnetic stirring, the mixture is reacted at a temperature of 90° C. for 24 hours. After the reaction is completed, the mixture is cooled to room temperature and the solid is filtered out. The solid is washed with anhydrous ethanol and deionized water in sequence and then dried to obtain a compatibilizer. The fourth step is to use 200 mL of 68% concentrated nitric acid and 100 mL of 98% concentrated sulfuric acid to prepare a mixed acid solution in a reaction bottle equipped with a condenser, a thermometer, and a magnetic stirring rotor. Then, 55 g of conductive carbon black is added to the mixed acid solution, and the magnetic stirring is turned on and the reaction is carried out at room temperature for 6 hours. After the reaction is completed, the solid is filtered out, washed with deionized water, and then dried to obtain a modified conductive filler.

[0028] Step 5: Dry and mix 280g of modified polyphenylene ether (polyphenylene ether mass fraction is 50%), 20g of compatibilizer, 120g of high-density polyethylene, 50g of modified conductive filler, 2g of antioxidant 1010, 0.5g of sodium hypophosphite, and 10g of DOPO, and add them into a nitrogen-protected twin-screw extruder for melt extrusion at a temperature of 255°C. After cooling and pulling, they are sheathed on the outer surface of the fiber core to obtain an engine wiring harness with good shielding properties.

[0029] An engine wiring harness with good shielding performance is prepared by the above preparation steps.

[0030] Example 2:

[0031] A method for preparing an engine wiring harness with good shielding properties comprises the following steps: The first step is to mix 20mmol 4,4'-diaminodiphenyl disulfide, 70mmol triethylamine, and 55mL dichloromethane in a reaction flask equipped with a condenser, a thermometer, and a magnetic stirring rotor. After turning on the magnetic stirring, 44mmol carbon disulfide is added dropwise to the reaction flask for 45min. After the addition is complete, the reaction is continued at room temperature for 2.5h. The reaction flask is then cooled with an ice-water bath, and a solution prepared by adding 44mmol tert-butyl carbonate diethyl phosphoric anhydride and 27.5mL dichloromethane is added dropwise to the reaction flask for 20min. After the addition is complete, the ice-water bath is removed and the reaction is continued for 3.5h. After the reaction is completed, the pH of the system is adjusted to 6 using dilute hydrochloric acid, and then the organic phase is separated. The organic phase is evaporated to remove the solvent and then eluted by silica gel column chromatography to obtain a modifier; Step 2: 20 g of polyphenylene ether and 70 g of toluene were mixed in a reaction flask equipped with a condenser, a thermometer, and a magnetic stirring rotor. The system temperature was raised to 100° C. and stirred until completely dissolved. Then, 1 g of benzoyl peroxide was added to the reaction flask, and the reaction was continued at 100° C. for 1.5 h. Then, 2.5 g of a modifier was added to the reaction flask, and the reaction was continued at 100° C. for 50 min. After the reaction was completed, the reaction solution was cooled to room temperature and filtered. The obtained solid was washed with anhydrous ethanol and dried to obtain polyphenylene ether with disulfide bonds. The third step is to use an electron accelerator as an irradiation source to pre-irradiate the high-density polyethylene powder with beta rays. The irradiation conditions are an acceleration voltage of 4 MeV and a current of 9.6 mA. Under nitrogen protection, 20 g of irradiated high-density polyethylene powder, 15 g of polyphenylene ether with a disulfide bond, 1.4 g of tert-butyl peroxy-2-ethylhexanoate, and 90 mL of toluene are added to a reaction bottle equipped with a magnetic stirring rotor. After turning on the magnetic stirring, the mixture is reacted at a temperature of 105 ° C for 16 hours. After the reaction is completed, the mixture is cooled to room temperature and the solid is filtered out. The solid is washed with anhydrous ethanol and deionized water in sequence and then dried to obtain a compatibilizer. The fourth step is to use 250 mL of 68% concentrated nitric acid and 125 mL of 98% concentrated sulfuric acid to prepare a mixed acid solution in a reaction bottle equipped with a condenser, a thermometer, and a magnetic stirring rotor. Then, 60 g of conductive carbon black is added to the mixed acid solution, and the magnetic stirring is turned on and the reaction is carried out at room temperature for 7 hours. After the reaction is completed, the solid is filtered out, washed with deionized water, and then dried to obtain a modified conductive filler.

[0032] Step 5: Dry and mix 260g of modified polyphenylene ether (the mass fraction of polyphenylene ether is 55%), 20g of compatibilizer, 140g of high-density polyethylene, 55g of modified conductive filler, 2g of antioxidant 1010, 1g of antioxidant 168, and 15g of DOPO, and add them into a nitrogen-protected twin-screw extruder for melt extrusion at a melt extrusion temperature of 250°C. After cooling and pulling, they are sheathed on the outer surface of the fiber core to obtain an engine wiring harness with good shielding properties.

[0033] An engine wiring harness with good shielding performance is prepared by the above preparation steps.

[0034] Example 3:

[0035] A method for preparing an engine wiring harness with good shielding properties comprises the following steps: The first step is to mix 20mmol 4,4'-diaminodiphenyl disulfide, 80mmol triethylamine, and 60mL dichloromethane in a reaction flask equipped with a condenser, a thermometer, and a magnetic stirring rotor. After turning on the magnetic stirring, 46mmol carbon disulfide is added dropwise to the reaction flask for 60min. After the addition is complete, the reaction is continued at room temperature for 2h. The reaction flask is then cooled with an ice-water bath, and a solution prepared by adding 46mmol tert-butyl carbonate diethyl phosphoric anhydride and 30mL dichloromethane is added dropwise to the reaction flask for 25min. After the addition is complete, the ice-water bath is removed and the reaction is continued for 3h. After the reaction is completed, the pH of the system is adjusted to 7 with dilute hydrochloric acid, and then the organic phase is separated. The organic phase is evaporated to remove the solvent and then eluted by silica gel column chromatography to obtain a modifier; Step 2: 20 g of polyphenylene ether and 80 g of toluene were mixed in a reaction flask equipped with a condenser, a thermometer, and a magnetic stirring rotor. The system temperature was raised to 110° C. and stirred until completely dissolved. 1.2 g of dicumyl peroxide was then added to the reaction flask, and the reaction was continued at 110° C. for 1.5 h. 3 g of a modifier was then added to the reaction flask, and the reaction was continued at 110° C. for 40 min. After the reaction was completed, the reaction solution was cooled to room temperature and filtered. The obtained solid was washed with anhydrous ethanol and dried to obtain polyphenylene ether with disulfide bonds. The third step is to use an electron accelerator as an irradiation source to pre-irradiate the high-density polyethylene powder with beta rays. The irradiation conditions are an acceleration voltage of 3MeV and a current of 7.2mA. Under nitrogen protection, 25g of irradiated high-density polyethylene powder, 15g of polyphenylene ether with a disulfide bond, 1.6g of tert-butyl peroxycarbonate-2-ethylhexyl ester, and 100mL of toluene are added to a reaction bottle equipped with a magnetic stirring rotor. After turning on the magnetic stirring, the mixture is reacted at a temperature of 120°C for 8h. After the reaction is completed, the mixture is cooled to room temperature and the solid is filtered out. The solid is washed with anhydrous ethanol and deionized water in sequence and then dried to obtain a compatibilizer. Step 4: Use 300 mL of 68% concentrated nitric acid and 150 mL of 98% concentrated sulfuric acid to prepare a mixed acid solution in a reaction bottle equipped with a condenser, a thermometer, and a magnetic stirring rotor. Then, add 65 g of conductive carbon black to the mixed acid solution, turn on the magnetic stirring, and react at room temperature for 8 hours. After the reaction is completed, filter out the solid, wash it with deionized water, and then dry it to obtain a modified conductive filler.

[0036] Step 5: Dry and mix 240g modified polyphenylene ether, 20g compatibilizer, 160g high-density polyethylene, 60g modified conductive filler, 2.5g antioxidant 1035, 1g antioxidant 168, and 20g OPOPB, and add them into a nitrogen-protected twin-screw extruder for melt extrusion at a temperature of 245°C. After cooling and pulling, they are sleeved on the outer surface of the fiber core to obtain an engine wiring harness with good shielding properties.

[0037] An engine wiring harness with good shielding performance is prepared by the above preparation steps.

[0038] Comparative Example 1 The difference between this comparative example and Example 1 is that no compatibilizer is prepared, but a commercially available compatibilizer is used to improve the performance of the composite material.

[0039] A method for preparing an engine wiring harness with good shielding properties comprises the following steps: In the first step, 200 mL of 68% by mass concentrated nitric acid and 100 mL of 98% by mass concentrated sulfuric acid were used to prepare a mixed acid solution in a reaction bottle equipped with a condenser, a thermometer, and a magnetic stirring rotor. Then, 55 g of conductive carbon black was added to the mixed acid solution. After turning on the magnetic stirring, the mixture was reacted at room temperature for 6 hours. After the reaction was completed, the solid was filtered out, washed with deionized water, and then dried to obtain a modified conductive filler.

[0040] In the second step, 280g modified polyphenylene ether (polyphenylene ether mass fraction is 50%), 20g HDPE-g-PS, 120g high-density polyethylene, 50g modified conductive filler, 2g antioxidant 1010, 0.5g sodium hypophosphite, and 10g DOPO are dried and mixed, and then added into a nitrogen-protected twin-screw extruder for melt extrusion at a melt extrusion temperature of 255°C. After cooling and pulling, they are sleeved on the outer surface of the fiber core to obtain an engine wiring harness with good shielding properties.

[0041] An engine wiring harness with good shielding performance is prepared by the above preparation steps.

[0042] Experimental Example 1 The engine wiring harnesses in Examples 1 to 3 and Comparative Example 1 were subjected to flame retardancy tests, electromagnetic shielding tests, heat resistance tests, tensile strength tests, vibration durability tests, and impact strength tests. The test results are shown in Tables 1 and 2.

[0043] Flame retardant performance test: Tested with reference to the standard UL-94 vertical burning rating.

[0044] Electromagnetic shielding performance test, heat resistance test, vibration durability test: Tests are conducted in accordance with the national standard GB / T 37133-2018 "Technical Requirements for High-Voltage and High-Current Wiring Harnesses and Connectors for Electric Vehicles".

[0045] Tensile strength test: Tested in accordance with the national standard GB / T 1040.1-2025 "Test for tensile properties of plastics".

[0046] Impact strength test: Tested in accordance with the national standard GB / T 1043.1-2008 “Determination of impact properties of simply supported beams of plastics”.

[0047] Table 1

[0048] Table 2

[0049] From Table 1 and Table 2, it can be seen that the engine harnesses of the present invention in Examples 1 to 3 have better heat resistance and flame retardancy, the shielding effectiveness reaches the E3 standard, and can pass the vibration test, and have better tensile strength and impact strength, and can be widely used in the field of new energy vehicle engines.

[0050] The above embodiments are intended only to facilitate understanding of the methods and core concepts of the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is intended to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an engine wiring harness with good shielding properties, characterized in that: The following steps are involved: A modifier is obtained by rearrangement reaction of 4,4′-diaminodiphenyl disulfide and carbon disulfide under the action of tert-butyl carbonate diethyl phosphoric anhydride, and an initiator is used to oxidatively crack polyphenylene ether. The cracked polyphenylene ether reacts with the modifier to obtain polyphenylene ether with a disulfide bond. The irradiated high-density polyethylene powder and the polyphenylene ether with a disulfide bond react in the initiator to obtain a compatibilizer. The conductive filler is oxidized to obtain a modified conductive filler. The modified polyphenylene ether, compatibilizer, high-density polyethylene, modified conductive filler, antioxidant, and flame retardant are dried, mixed, melt-extruded, cooled, and pulled, and then sleeved on the outer surface of the fiber core to obtain an engine wiring harness with good shielding properties.

2. The method for preparing an engine wiring harness with good shielding properties according to claim 1, characterized in that: The initiator used for oxidative cleavage of polyphenylene ether is at least one of benzoyl peroxide and dicumyl peroxide.

3. The method for preparing an engine wiring harness with good shielding properties according to claim 1, characterized in that: The initiator used for preparing the compatibilizer is at least one of tert-butyl peroxy-2-ethylhexanoate and tert-butyl peroxycarbonate-2-ethylhexyl ester.

4. The method for preparing an engine wiring harness with good shielding properties according to claim 1, characterized in that: The conductive filler is conductive carbon black.

5. The method for preparing an engine wiring harness with good shielding properties according to claim 1, characterized in that: The antioxidant is at least one of antioxidant 1010, antioxidant 1035, sodium hypophosphite, and antioxidant 168.

6. The method for preparing an engine wiring harness with good shielding properties according to claim 1, characterized in that: The flame retardant is a phosphate flame retardant.

7. The method for preparing an engine wiring harness with good shielding properties according to claim 1, characterized in that: The molar ratio of 4,4'-diaminodiphenyl disulfide, carbon disulfide, and tert-butyl carbonate diethyl phosphoric anhydride is 1:2.1-2.3:2.1-2.

3.

8. The method for preparing an engine wiring harness with good shielding properties according to claim 1, characterized in that: The mass ratio of polyphenylene ether, initiator and modifier is 20: 0.8~1.2:2~3, the mass ratio of polyethylene, polyphenylene ether with disulfide bonds, and initiator is 15~25:15:1.2~1.6, and the mass ratio of modified polyphenylene ether, compatibilizer, high-density polyethylene, conductive filler, antioxidant, and flame retardant is 240~280:20:120~160:50~60:2.5~3.5:10~20.

9. The method for preparing an engine wiring harness with good shielding properties according to claim 1, characterized in that: The temperature condition of melt extrusion is 245 to 255°C.

10. An engine wiring harness with good shielding properties, characterized in that: An engine wiring harness with good shielding properties is prepared by the preparation method described in any one of claims 1 to 9.

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