Engine wire harness with good shielding property and manufacturing method thereof

Abstract

The application relates to an engine wire harness with good shielding performance and a preparation method thereof, and belongs to the technical field of new energy vehicles; a compatilizer is prepared, the compatilizer is a polyphenyl ether-polyethylene graft copolymer, the polyphenyl ether chain segment in the molecular structure is compatible with polyphenyl ether, and the polyethylene chain segment is compatible with high-density polyethylene; the structure can significantly reduce the interfacial tension between the polyphenyl ether / high-density polyethylene two phases, greatly enhance the interfacial adhesion, effectively inhibit phase separation and interfacial peeling, effectively improve the mechanical properties of the material, in addition, the compatilizer does not need to introduce a new resin component, potential influences of external components on the properties of the matrix are avoided, and the inherent properties of the polyphenyl ether and high-density polyethylene matrix resins can be better reserved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new energy vehicles, and particularly relates to an engine wire harness with good shielding performance and a preparation method thereof. BACKGROUND

[0002] In the high-voltage electrical architecture of a new energy vehicle, an engine wire harness is a core carrier for electric energy transmission, and the reliability thereof is directly related to the power performance and safe operation of the vehicle. High-density polyethylene has excellent mechanical properties, oil resistance, and low cost, and is therefore widely used as an outer sheath material of an engine wire harness. However, as the power density of a new energy driving system continues to rise, the thermal environment in a motor compartment is becoming increasingly severe, and the local temperature has broken through 140 DEG C, far exceeding the long-term use temperature of high-density polyethylene. In a long-term high-temperature environment, the molecular chains of the polymer will be oxidized and degraded, causing the sheath to soften, creep, and even melt, accompanied by thermal aging and embrittlement, which destroys the integrity of the outer sheath and greatly affects the shielding performance of the engine wire harness. To solve the above technical defects, the application provides an engine wire harness with good shielding performance and a preparation method thereof. SUMMARY

[0003] The application aims to provide an engine wire harness with good shielding performance and a preparation method thereof, which are used to solve the problems mentioned in the background.

[0004] The application can be achieved by the following technical solutions.

[0005] A preparation method of an engine wire harness with good shielding performance comprises the following steps.

[0006] In the first step, 4,4'-diaminodiphenyl disulfide, triethylamine, and dichloromethane are mixed in a reaction bottle provided with a condenser, a thermometer, and a magnetic stirring rotor. After the magnetic stirring is started, carbon disulfide is added dropwise to the reaction bottle at a dropwise adding time of 30-60 min. After the dropwise adding is completed, the reaction is continued at room temperature for 2-3 h. Then, the reaction bottle is cooled with an ice water bath, and a solution of diethylphosphinic acid t-butyl ester in dichloromethane is added dropwise to the reaction bottle at a dropwise adding time of 15-25 min. After the dropwise adding is completed, the ice water bath is removed, and the reaction is continued for 3-4 h. After the reaction is completed, the pH of the system is adjusted to 5-7 by using dilute hydrochloric acid. Then, the organic phase is separated. After the solvent is removed from the organic phase by rotary evaporation, the modified agent is obtained by silica gel column chromatography.

[0007] The amino group of 4,4'-diaminodiphenyl disulfide is rearranged under the action of carbon disulfide and diethylphosphinic acid t-butyl ester to obtain the modified agent.

[0008] The second step is to mix polyphenyl ether and toluene in a reaction bottle provided with a condenser, a thermometer and a magnetic stirring rotor, to raise the temperature of the system to 90-110 DEG C and to stir until complete dissolution, then to add an initiator to the reaction bottle and to continue the reaction at a temperature of 90-110 DEG C for 1.5 hours, then to add a modifier to the reaction bottle and to continue the reaction at a temperature of 90-110 DEG C for 40-60 minutes, and after the reaction is completed, to cool the reaction liquid to room temperature and to filter, to wash the obtained solid with anhydrous ethanol and to dry to obtain polyphenyl ether with a disulfide bond;

[0009] The initiator is used to oxidatively cleave the polyphenyl ether to obtain low-molecular-weight polyphenyl ether, and then the hydroxyl groups in the low-molecular-weight polyphenyl ether react with isothiocyanate groups in the modifier to obtain polyphenyl ether with a disulfide bond.

[0010] The third step is to pre-irradiate high-density polyethylene powder, and to add the irradiated high-density polyethylene powder, polyphenyl ether with a disulfide bond, an initiator and toluene to a reaction bottle provided with a magnetic stirring rotor under nitrogen protection, to start magnetic stirring and to react at a temperature of 90-120 DEG C for 8-24 hours, and after the reaction is completed, to cool to room temperature and to filter out the solid, to wash with anhydrous ethanol and deionized water in sequence and to dry to obtain a compatibilizer.

[0011] The irradiation of the high-density polyethylene powder greatly increases the content of hydroxyl groups in the structure, and the polyphenyl ether with a disulfide bond is broken by the initiator to generate sulfur radicals which attack double bonds in the structure of the irradiated high-density polyethylene powder, to obtain a compatibilizer which can be used to improve the compatibility of polyphenyl ether and polyethylene.

[0012] The fourth step is to obtain modified conductive filler by oxidizing conductive filler.

[0013] Oxidation can effectively increase the number of oxygen-containing groups on the surface of the conductive filler.

[0014] The fifth step is to dry and mix modified polyphenyl ether, a compatibilizer, high-density polyethylene, modified conductive filler, antioxidant and flame retardant, to melt-extrude in a nitrogen-protected double-screw extruder, to cool and pull, and to cover the outer surface of the core to obtain an engine wire harness with good shielding performance.

[0015] As a further preferred embodiment of the present application, the initiator in the second step is at least one of benzoyl peroxide and dicumyl peroxide.

[0016] As a further preferred embodiment of the present application, the initiator in the third step is at least one of tert-butyl peroxide-2-ethylhexanoate and tert-butyl peroxide carbonate-2-ethylhexyl.

[0017] As a further preferred embodiment of the present application, the conductive filler in the fourth step is conductive carbon black.

[0018] As a further preferred embodiment of the present application, the antioxidant in the fifth step is at least one of antioxidant 1010, antioxidant 1035, sodium hypophosphite, antioxidant 168.

[0019] As a further preferred embodiment of the present application, the flame retardant in the fifth step is a phosphate ester flame retardant, including at least one of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide (OPOPB).

[0020] As a further preferred embodiment of the present application, the mass ratio of 4,4'-diaminodiphenyl disulfide, carbon disulfide, and tertiary butyl carbonic acid diethyl phosphoric anhydride in the first step is 1:2.1-2.3:2.1-2.3.

[0021] As a further preferred embodiment of the present application, the mass ratio of polyphenyl ether, initiator, and modifier in the second step is 20:0.8-1.2:2-3.

[0022] As a further preferred embodiment of the present application, the mass ratio of polyethylene, polyphenyl ether with disulfide bond, and initiator in the third step is 15-25:15:1.2-1.6.

[0023] As a further preferred embodiment of the present application, the modified polyphenyl ether is polyphenyl ether, polystyrene blend, and the mass fraction of polyphenyl ether in the modified polyphenyl ether is 50-60%.

[0024] As a further preferred embodiment of the present application, the mass ratio of modified polyphenyl ether, compatibilizer, high-density polyethylene, modified conductive filler, antioxidant, and flame retardant in the fifth step is 240-280:20:120-160:50-60:2.5-3.5:10-20.

[0025] As a further preferred embodiment of the present application, the temperature condition of melt extrusion in the fifth step is 245-255°C.

[0026] An engine wire harness with good shielding prepared by any of the above preparation steps.

[0027] The present application has at least one of the following beneficial effects:

[0028] The compatibilizer of the present application is a polyphenylene ether-polyethylene graft copolymer, the polyphenylene ether segment in the molecular structure is compatible with polyphenylene ether, and the polyethylene segment is compatible with high-density polyethylene. This structure can significantly reduce the interfacial tension between the two phases of polyphenylene ether / high-density polyethylene, greatly enhance the interfacial adhesion, effectively inhibit phase separation and interfacial peeling. In the process of melt blending, the compatibilizer can stabilize the dispersed phase of polyphenylene ether droplets by reducing the interfacial energy, effectively prevent its coarsening and coalescence, and promote the size of polyphenylene ether phase to be significantly reduced and uniformly distributed. Finally, a fine and stable phase morphology structure is formed. The optimization of this microstructure can effectively improve the mechanical properties (such as tensile strength and impact toughness) of the material. In addition, the present compatibilizer does not need to introduce new resin components, avoiding the potential influence of external components on the performance of the matrix, and better preserving the inherent properties of polyphenylene ether and high-density polyethylene matrix resin.

[0029] The present application uses modified polyphenylene ether and high-density polyethylene to obtain a composite material. A large number of ether bonds and thioether structures exist in the structure of the composite material, which can not only act as hydrogen bond acceptors to form hydrogen bonds with the carboxyl groups in the oxidized conductive filler, but also significantly improve the dispersibility of the conductive filler in the outer sheath, improve the interfacial bonding ability of the conductive filler and the composite material (mainly the polyphenylene ether phase) in the outer sheath, and promote the interfacial enrichment of the conductive network in the polyphenylene ether phase, so that a high-efficiency and low-permeation-threshold conductive network can be constructed with less additive amount.

[0030] The present application uses polyphenylene ether with excellent heat resistance and intrinsic flame retardancy to be compounded with high-density polyethylene, which significantly overcomes the shortcomings of single polyolefin material 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 high-temperature use environment, and effectively avoid the influence of the brittleness and cracking of the outer sheath on the integrity of the outer sheath. At the same time, the polyphenylene ether molecular structure contains inherent flame-retardant structures and additional sulfur-containing groups, which can also produce a synergistic effect with phosphorus-based flame retardants, catalyze the formation of phosphorus-oxygen radicals, promote charring, heat and oxygen insulation during combustion, and by compounding with HDPE, not only significantly improve the overall heat resistance grade and upper limit of use temperature of the outer sheath, but also effectively reduce the addition amount of the flame retardant, thereby effectively maintaining the toughness of the material and improving the processing performance of the material. DETAILED DESCRIPTION

[0031] The technical solutions of the embodiments of the present application will be described below. Obviously, the described embodiments are part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of the present application.

[0032] Wherein, all raw materials of the present application have no special restrictions on their sources, and can be purchased on the market or prepared according to conventional methods well known to those skilled in the art.

[0033] Example 1:

[0034] A preparation method of an engine wire harness with good shielding performance, comprising the following steps:

[0035] Step 1, 20 mmol of 4,4'-diaminodiphenyl disulfide, 60 mmol of triethylamine and 50 mL of dichloromethane were mixed in a reaction bottle equipped with a condenser, a thermometer and a magnetic stirring rotor. After the magnetic stirring was started, 42 mmol of carbon disulfide was added dropwise into the reaction bottle, the dropwise addition time was 30 min. After the dropwise addition was completed, the reaction was continued at room temperature for 3 h. Then the reaction bottle was cooled with an ice water bath, and a solution prepared by mixing 42 mmol of diethyl phosphate anhydride of tert-butyl carbonic acid and 25 mL of dichloromethane was added dropwise into the reaction bottle, the dropwise addition time was 15 min. After the dropwise addition was completed, the ice water bath was removed, and the reaction was continued for 4 h. After the reaction was completed, the pH of the system was adjusted to 5 using dilute hydrochloric acid. Then the organic phase was separated. After the solvent was removed from the organic phase by rotary evaporation, the modified agent was eluted by silica gel column chromatography.

[0036] Step 2, 20 g of polyphenyl ether and 60 g of toluene were mixed in a reaction bottle equipped with a condenser, a thermometer and a magnetic stirring rotor. The temperature of the system was raised to 90℃ and stirred until completely dissolved. Then 0.8 g of benzoyl peroxide was added into the reaction bottle, and the reaction was continued at a temperature of 90℃ for 1.5 h. Then 2 g of the modified agent was added into the reaction bottle, and the reaction was continued at a temperature of 90℃ for 60 min. After the reaction was completed, the reaction liquid was cooled to room temperature and filtered. The obtained solid was washed with anhydrous ethanol and dried to obtain polyphenyl ether with disulfide bond.

[0037] Step 3, an electron accelerator was used as an irradiation source, and β-rays were used to pre-irradiate high-density polyethylene powder. The irradiation conditions were an acceleration voltage of 5 MeV and a current of 12 mA. Under the protection of nitrogen, 15 g of the irradiated high-density polyethylene powder, 15 g of polyphenyl ether with disulfide bond, 1.2 g of tert-butyl peroxy-2-ethylhexanoate and 80 mL of toluene were added into a reaction bottle equipped with a magnetic stirring rotor. After the magnetic stirring was started, the reaction was carried out at a temperature of 90℃ for 24 h. After the reaction was completed, the reaction liquid was cooled to room temperature and the solid was filtered out. After being washed with anhydrous ethanol and deionized water in sequence, the solid was dried to obtain the compatibilizer.

[0038] Fourth step, using 200 mL of 68% mass fraction of concentrated nitric acid and 100 mL of 98% mass fraction of concentrated sulfuric acid in the installation of condenser, thermometer, magnetic stirring rotor reaction bottle in the preparation of mixed acid solution, then to the mixed acid solution into 55 g of conductive carbon black, open magnetic stirring after reaction at room temperature for 6 h, after the reaction, filter out the solid and washed with deionized water after drying to obtain modified conductive filler.

[0039] Fifth step, 280 g of modified polyphenyl ether (polyphenyl ether mass fraction of 50%), 20 g of compatibilizer, 120 g of high density polyethylene, 50 g of modified conductive filler, 2 g of antioxidant 1010, 0.5 g of sodium hypophosphite, 10 g of DOPO dry and mixed, then added into the nitrogen protection double screw extruder melt extrusion, melt extrusion temperature is 255 ℃, then after cooling, traction after set on the outer surface of the core can get good shielding engine wire harness.

[0040] A good shielding engine wire harness is prepared by the above preparation steps.

[0041] Example 2:

[0042] A method for preparing a good shielding engine wire harness, comprising the following steps:

[0043] First step, 20 mmol of 4,4'-diaminodiphenyl disulfide, 70 mmol of triethylamine, 55 mL of dichloromethane are mixed in a reaction bottle equipped with a condenser, a thermometer and a magnetic stirring rotor, and then 44 mmol of carbon disulfide is added dropwise into the reaction bottle under magnetic stirring. The dropwise time is 45 min. After the dropwise addition is completed, the reaction is continued at room temperature for 2.5 h. Then the reaction bottle is cooled with an ice water bath, and a solution prepared by mixing 44 mmol of tert-butyl carbonic acid diethyl phosphoric anhydride and 27.5 mL of dichloromethane is added dropwise into the reaction bottle. The dropwise time is 20 min. After the dropwise addition is completed, the ice water bath is removed, and the reaction is continued for 3.5 h. After the reaction is completed, the pH of the system is adjusted to 6 using dilute hydrochloric acid. Then the organic phase is separated. The solvent in the organic phase is removed by rotary evaporation, and then the organic phase is subjected to silica gel column chromatography to obtain a modifier.

[0044] Second step, 20 g of polyphenyl ether and 70 g of toluene are mixed in a reaction bottle equipped with a condenser, a thermometer and a magnetic stirring rotor. The temperature of the system is raised to 100 ℃ and stirred until completely dissolved. Then 1 g of benzoyl peroxide is added into the reaction bottle, and the reaction is continued at a temperature of 100 ℃ for 1.5 h. Then 2.5 g of the modifier is added into the reaction bottle, and the reaction is continued at a temperature of 100 ℃ for 50 min. After the reaction is completed, the reaction liquid is cooled to room temperature and filtered. The obtained solid is washed with anhydrous ethanol and dried to obtain polyphenyl ether with disulfide bond.

[0045] Third step, using an electron accelerator as the irradiation source, using beta rays to pre-irradiate high-density polyethylene powder, the irradiation conditions are that the acceleration voltage is 4 MeV, the current is 9.6 mA, and 20 g of the irradiated high-density polyethylene powder is added into a reaction bottle provided with a magnetic stirring rotor together with 15 g of polyphenyl ether with a disulfide bond, 1.4 g of tert-butyl peroxy-2-ethylhexanoate, and 90 mL of toluene under nitrogen protection, and then the magnetic stirring is started, and the reaction is carried out at a temperature of 105 DEG C for 16 h, after the reaction is completed, the system is cooled to room temperature, and the solid is filtered out, and then the solid is washed with anhydrous ethanol and deionized water in sequence and dried to obtain a compatilizer;

[0046] Fourth step, a mixed acid solution is prepared in a reaction bottle provided with a condenser, a thermometer, and a magnetic stirring rotor by using 250 mL of concentrated nitric acid with a mass fraction of 68% and 125 mL of concentrated sulfuric acid with a mass fraction of 98%, then 60 g of conductive carbon black is added into the mixed acid solution, the magnetic stirring is started, and the reaction is carried out at room temperature for 7 h, after the reaction is completed, the solid is filtered out and washed with deionized water and then dried to obtain a modified conductive filler.

[0047] Fifth step, 260 g of modified polyphenyl ether (the mass fraction of polyphenyl ether is 55%), 20 g of the compatilizer, 140 g of high-density polyethylene, 55 g of the modified conductive filler, 2 g of antioxidant 1010, 1 g of antioxidant 168, and 15 g of DOPO are dried and mixed, and then added into a nitrogen-protected double-screw extruder for melt extrusion, the melt extrusion temperature is 250 DEG C, and then the engine wire harness with good shielding property is obtained by sleeving the outer surface of the fiber core after cooling and traction.

[0048] An engine wire harness with good shielding property is prepared by the above preparation steps.

[0049] Example 3:

[0050] A preparation method of an engine wire harness with good shielding property comprises the following steps:

[0051] First step, 20 mmol of 4,4'-diaminodiphenyl disulfide, 80 mmol of triethylamine, and 60 mL of dichloromethane are mixed in a reaction bottle provided with a condenser, a thermometer, and a magnetic stirring rotor, then 46 mmol of carbon disulfide is added dropwise into the reaction bottle at a dropwise adding time of 60 min, after the dropwise adding is completed, the reaction is continuously carried out at room temperature for 2 h, then the reaction bottle is cooled by an ice water bath, and a solution prepared by mixing 46 mmol of tert-butyl carbonic acid diethyl phosphinic anhydride and 30 mL of dichloromethane is added dropwise into the reaction bottle at a dropwise adding time of 25 min, after the dropwise adding is completed, the ice water bath is removed, and the reaction is continuously carried out for 3 h, after the reaction is completed, the pH of the system is adjusted to 7 by using dilute hydrochloric acid, then the organic phase is separated, the solvent is removed from the organic phase by rotary evaporation, and then the modified agent is eluted by silica gel column chromatography to obtain a modified agent.

[0052] Second step, 20g polyphenyl ether, 80g toluene is mixed in the reaction bottle installed with condenser, thermometer, magnetic stirring rotor, the system temperature is raised to 110℃ and stirred until completely dissolved, then 1.2g dicumyl peroxide is added to the reaction bottle, and the reaction is continued at 110℃ for 1.5h, then 3g modifier is added to the reaction bottle, and the reaction is continued at 110℃ for 40min, after the reaction is completed, the reaction liquid is cooled to room temperature and filtered, the obtained solid is washed with anhydrous ethanol and dried to obtain polyphenyl ether with disulfide bond;

[0053] Third step, using an electron accelerator as the irradiation source, the high-density polyethylene powder is pre-irradiated by beta rays, the irradiation conditions are acceleration voltage 3MeV, current 7.2mA, and 25g irradiated high-density polyethylene powder, 15g polyphenyl ether with disulfide bond, 1.6g tert-butyl peroxide-2-ethylhexyl carbonate, 100mL toluene are added to the reaction bottle with magnetic stirring rotor, the magnetic stirring is started, and the reaction is carried out at 120℃ for 8h, after the reaction is completed, it is cooled to room temperature and the solid is filtered out, then it is washed with anhydrous ethanol and deionized water in turn and dried to obtain the compatilizer;

[0054] Fourth step, 300mL of 68% concentrated nitric acid and 150mL of 98% concentrated sulfuric acid are used to prepare mixed acid liquid in a reaction bottle installed with condenser, thermometer and magnetic stirring rotor, then 65g conductive carbon black is added to the mixed acid liquid, the magnetic stirring is started, and the reaction is carried out at room temperature for 8h, after the reaction is completed, the solid is filtered out and washed with deionized water and dried to obtain the modified conductive filler.

[0055] Fifth step, 240g modified polyphenyl ether, 20g compatilizer, 160g high-density polyethylene, 60g modified conductive filler, 2.5g antioxidant 1035, 1g antioxidant 168, 20g OPOPB are dried and mixed, then they are added to the nitrogen-protected double screw extruder for melt extrusion, the melt extrusion temperature is 245℃, then the cooling and traction are carried out, and the engine wire harness with good shielding property is obtained by setting on the outer surface of the core.

[0056] An engine wire harness with good shielding property is prepared by the above preparation steps.

[0057] Comparative example 1

[0058] The difference between this comparative example and example 1 is that the compatilizer is not prepared, but a commercially available compatilizer is used to improve the performance of the composite material.

[0059] A preparation method of an engine wire harness with good shielding property, comprising the following steps:

[0060] The first step, using 200 mL of 68% concentrated nitric acid and 100 mL of 98% concentrated sulfuric acid, a mixed acid solution was prepared 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, and the magnetic stirring was started. After 6 hours of reaction at room temperature, the solid was filtered and washed with deionized water, and then dried to obtain the modified conductive filler.

[0061] The second step, 280 g of modified polyphenyl ether (polyphenyl ether mass fraction of 50%), 20 g of HDPE-g-PS, 120 g of high-density polyethylene, 50 g of modified conductive filler, 2 g of antioxidant 1010, 0.5 g of sodium hypophosphite, and 10 g of DOPO were dried and mixed, and then added to a nitrogen-protected twin-screw extruder for melt extrusion. The melt extrusion temperature was 255°C. After cooling and pulling, the engine wire harness with good shielding performance was obtained by wrapping the outer surface of the core.

[0062] An engine wire harness with good shielding performance is prepared by the above preparation steps.

[0063] Experimental Example 1

[0064] The engine wire harnesses in Examples 1-3 and Comparative Example 1 were tested for flame retardant performance, electromagnetic shielding performance, heat resistance, tensile strength, vibration durability, and impact strength. The test results are shown in Tables 1 and 2.

[0065] Flame retardant performance test: tested according to the standard UL-94 vertical burning grade.

[0066] Electromagnetic shielding performance test, heat resistance test, vibration durability test: tested according to the national standard GB / T 37133-2018 "Technical requirements for high-voltage and high-current wire harnesses and connectors for electric vehicles".

[0067] Tensile strength test: tested according to the national standard GB / T 1040.1-2025 "Test methods for tensile properties of plastics".

[0068] Impact strength test: tested according to the national standard GB / T 1043.1-2008 "Determination of the Charpy Impact Properties of Plastics".

[0069] Table 1

[0070]

[0071] Table 2

[0072]

[0073] It can be seen from Tables 1 and 2 that the engine harnesses of the application in Examples 1-3 have better heat resistance and flame retardance, the shielding effectiveness reaches the E3 standard, can pass the vibration experiment, and have better tensile strength and impact strength, and can be widely applied in the field of new energy automobile engines.

[0074] The above description of the examples is merely meant to aid in understanding the method of the application and its core idea. Various modifications to these examples will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other examples without departing from the spirit or scope of the application. Therefore, the application will not be limited to these examples shown herein, but will accord with the widest scope 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, Includes the following steps: A modifier is obtained by rearranging 4,4′-diaminodiphenyl disulfide and carbon disulfide under the action of tert-butyl carbonate diethylphosphoric anhydride. Polyphenylene ether is then oxidized and cracked using an initiator. The cracked polyphenylene ether reacts with the modifier to obtain polyphenylene ether with disulfide bonds. Then, irradiated high-density polyethylene powder reacts with the polyphenylene ether with disulfide bonds under an initiator to obtain a compatibilizer. A modified conductive filler is obtained by oxidizing the conductive filler. Finally, the modified polyphenylene ether, compatibilizer, high-density polyethylene, modified conductive filler, antioxidant, and flame retardant are dried, mixed, melt-extruded, cooled, and drawn, and then applied to the outer surface of the fiber core to obtain a well-shielded engine wiring harness. The modified polyphenylene ether is a blend of polyphenylene ether and polystyrene, and the mass fraction of polyphenylene ether in the modified polyphenylene ether is 50-60%. The initiator used to prepare the compatibilizer is at least one of tert-butyl peroxide-2-ethylhexanoate and tert-butyl peroxycarbonate-2-ethylhexyl ester.

2. The method for preparing a well-shielded engine wiring harness according to claim 1, characterized in that, The initiator used for oxidative cracking of polyphenylene ether is at least one of benzoyl peroxide and dicumyl peroxide.

3. The method for preparing a well-shielded engine wiring harness according to claim 1, characterized in that, The conductive filler is conductive carbon black.

4. The method for preparing a well-shielded engine wiring harness according to claim 1, characterized in that, The antioxidant is at least one of antioxidant 1010, antioxidant 1035, sodium hypophosphite, and antioxidant 168.

5. The method for preparing a well-shielded engine wiring harness according to claim 1, characterized in that, The flame retardant is a phosphate ester flame retardant.

6. The method for preparing a well-shielded engine wiring harness according to claim 1, characterized in that, The molar ratio of 4,4′-diaminodiphenyl disulfide, carbon disulfide, and tert-butyl carbonate diethylphosphoric anhydride is 1:2.1-2.3:2.1-2.

3.

7. The method for preparing a well-shielded engine wiring harness according to claim 1, characterized in that, The mass ratio of initiator to modifier used in polyphenylene ether and pyrolytic polyphenylene ether is 20: The mass ratio of high-density polyethylene, polyphenylene ether with disulfide bonds, and initiator used in preparing the compatibilizer is 15-25:15:1.2-1.

6. The mass ratio of modified polyphenylene ether, compatibilizer, high-density polyethylene for preparing engine wiring harnesses with good shielding properties, conductive filler, antioxidant, and flame retardant is 240-280:20:120-160:50-60:2.5-3.5:10-20.

8. The method for preparing a well-shielded engine wiring harness according to claim 1, characterized in that, The temperature conditions for melt extrusion are 245–255℃.

9. A well-shielded engine wiring harness, characterized in that, A shielded engine wiring harness is prepared by the preparation method described in any one of claims 1 to 8.

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