High-temperature-resistant automobile wire harness and preparation method thereof

Abstract

The application discloses a kind of high-temperature-resistant automobile harness and preparation method thereof, it is related to automobile harness technical field, including following process: S1.open line: according to production demand cutting guide wire;S2.press connection: stripping the protective layer and sheath layer of the outer surface of guide wire, reverse bending and pruning the shielding layer of guide wire end, expose the core wire of guide wire end;In the core wire end of guide wire, terminal is pressed, and terminal guide wire is obtained;S3.sealing: in the outer surface of terminal guide wire, sheath layer is set, and harness is obtained;S4.detection packaging: carry out loop conduction, line color, appearance, size detection, and package after passing;The application establishes automobile harness system by the cooperation of guide wire, terminal pressed in the core wire end of guide wire, shielding ring pressed in the outer surface of reverse bending guide wire shielding layer and sheath layer set in the outer surface of guide wire, to guarantee the normal operation of electrical system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile wiring harness, and particularly relates to a high-temperature-resistant automobile wiring harness and a preparation method thereof. BACKGROUND

[0002] The wiring harness can transmit the driving signals required by the automobile, drive the automobile, convert the signals into electric current, and transmit the electric current to other devices in the automobile, and is a total assembly of the automobile power and signal transmission distribution system. With the development of life and technology, people's requirements for economy, safety and comfort are continuously improved, and the electrical components on the automobile are continuously increased, and the wiring harness used is also more and more. The wiring harness is mainly composed of wires, terminals, sheaths and the like, and is a bridge and link for the work of the automobile electrical components. In order to maintain the normal and stable work of the automobile electrical components, in addition to ensuring the quality of the electrical components themselves, the state of the wiring harness on the vehicle is also closely related. In order to cope with the high-temperature environment in the vehicle operation, ensure the reliability of the electrical system, meet the safety regulations, and ensure the safety, reliability and long service life of the vehicle, with the development of new energy vehicles and intelligentization, the demand for the wiring harness will be further upgraded. Therefore, we propose a high-temperature-resistant automobile wiring harness and a preparation method thereof. SUMMARY

[0003] The present application aims to provide a high-temperature-resistant automobile wiring harness and a preparation method thereof to solve the problems in the background art.

[0004] In order to solve the above technical problems, the present application provides the following technical scheme: a high-temperature-resistant automobile wiring harness, comprising the following structures: wires, terminals, shielding rings and sheath layers.

[0005] Further, the wires sequentially comprise the following structures from inside to outside: core wires, shielding layers and protective layers.

[0006] Further, the shielding rings are crimped on the outer surfaces of the shielding layers in the wires.

[0007] Further, the terminals are crimped on the core wire end portions of the wires.

[0008] Further, the sheath layers are sleeved on the outer surfaces of the wires.

[0009] Further, the material of the sheath layer includes but is not limited to one or more of the following: PA (polyamide), ABS (acrylonitrile-butadiene-styrene copolymer), PBT (polybutylene terephthalate), PP (polypropylene), PVC (polyvinyl chloride), PE (polyethylene) and silicone rubber.

[0010] Further, the sheath layer comprises the following quality components: 70-85 parts of polypropylene, 5-10 parts of a toughening agent, 5-15 parts of a filler, and 1.5-3.5 parts of an auxiliary agent.

[0011] The auxiliary agent includes 0.5-1.5 parts of an antioxidant, 0.5-1.0 parts of a lubricant, 0.5-1.0 parts of a coupling agent.

[0012] Further, the toughening agent is one or more of a mixture of polyolefin elastomer (POE), methyl methacrylate-butadiene-styrene terpolymer (MBS), and maleic anhydride grafted ethylene-methyl methacrylate copolymer.

[0013] Further, the filler is a mixture of two or more of magnesium hydroxide, aluminum hydroxide, aluminum-magnesium hydrotalcite, talcum powder, and zinc oxide.

[0014] Further, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of (1-5) : 1.

[0015] Further, the lubricant is one of calcium stearate and magnesium stearate.

[0016] Further, the coupling agent is KH-550.

[0017] A preparation method of a high-temperature-resistant automobile wire harness, comprising the following processes:

[0018] S1. Opening the wire: cutting the guide wire according to production requirements;

[0019] S2. Crimping: stripping the protective layer and sheath layer on the outer surface of the guide wire, reversely bending and trimming the shielding layer at the end of the guide wire to expose the core wire at the end of the guide wire;

[0020] Crimping a terminal at the end of the core wire of the guide wire and crimping a shielding ring at the end of the shielding layer to obtain a terminal-equipped guide wire;

[0021] S3. Sealing: sleeving a sheath layer on the outer surface of the terminal-equipped guide wire to obtain a wire harness;

[0022] S4. Detection and packaging: performing loop conduction, wire color, appearance, and size detection, and packaging after passing the detection.

[0023] In the above technical solution, the shielding ring is pressed on the outer surface of the reversely bent shielding layer of the wire, for suppressing electromagnetic interference, managing leakage current, adjusting magnetic field distribution, so as to guarantee signal transmission quality, improve stability of the electrical system, and optimize insulation performance of the wire harness. The terminal is a component for connecting the wire with the electrical equipment, and is fastened with the wire in a manner such as pressing, so as to ensure reliability and stability of the electrical connection. The connector is arranged on the outer surface of the terminal, for connection between the wire harnesses and between the wire harness and the equipment, facilitating installation, disassembly and maintenance. The sheath layer is arranged on the outer surface of the wire, for insulation, protection, fixation and the like, and has good resistance to harsh environments such as high temperature, humidity and corrosion. Through mutual cooperation of the wire harness structure, the wire harness system for automobiles is established, so as to guarantee normal operation of the electrical system.

[0024] Further, the sheath layer is prepared by the following process:

[0025] The polypropylene is mixed with the toughening agent, the filler and the auxiliary agent, melt-extruded, granulated, to obtain polypropylene masterbatch; the polypropylene masterbatch is extruded and formed, and cooled, to obtain the sheath layer.

[0026] Further, the process condition for mixing is that the time length is 15-20 min, and the rotation speed is 200-400 rpm.

[0027] The melt-extrusion adopts a double-screw extruder, the extrusion temperature is 180-220℃, and the rotation speed is 40-80 rpm.

[0028] Further, in the extrusion and forming process, the extrusion temperature is 190-210℃, and the rotation speed is 40-80 rpm.

[0029] The cooling adopts water cooling at 20-30℃.

[0030] Further, after cutting, the sheath layer is annealed at a temperature of 60-70℃ for 2-4 h, so as to eliminate internal stress.

[0031] Further, the polypropylene is modified by using a benzoxazine-based compound and maleic anhydride before use, and the specific process is as follows:

[0032] The total mass of the benzoxazine-based compound and the initiator is 50%-70%, which is mixed with the polypropylene, and is reacted and extruded in an extruder, in the process, the maleic anhydride and the remaining initiator are added, to obtain the modified polypropylene.

[0033] Further, the modified polypropylene is prepared from the following mass components: 100 parts of polypropylene, 1-20 parts of benzoxazine-based compound, 1-10 parts of maleic anhydride, and 0.1-2 parts of initiator.

[0034] The initiator is one or a mixture of both of dicumyl peroxide and bis-tert-butyl peroxyisopropylbenzene.

[0035] Further, the total mass of the benzoxazine compound and the initiator is 50% to 70%, mixed and dissolved in acetone, and then mixed with the polypropylene powder.

[0036] The process conditions of the reactive extrusion are: temperature 160 to 190℃, rotation speed 40 to 60rpm.

[0037] Further, the benzoxazine compound is prepared by the following process:

[0038] Tris(2-aminoethoxy)borane and phenylphosphoryl dichloride are mixed, and then heated to 60 to 70℃ under nitrogen atmosphere for 6 to 8h; washed, dried, and then the polyamino compound is obtained.

[0039] The polyamino compound is dissolved in toluene / ethanol solution, and then polyformaldehyde and p-allylphenol are added, and then heated to 80 to 85℃ for 5 to 7h; the solvent is removed, washed, and dried, and then the benzoxazine compound is obtained.

[0040] Further, the molar ratio of tris(2-aminoethoxy)borane and phenylphosphoryl dichloride is (2.0 to 2.5) : 1.

[0041] Further, the molar ratio of the polyamino compound, polyformaldehyde, and p-allylphenol is 1: (4.2 to 4.5) : (4 to 5).

[0042] The ratio of the polyamino compound and toluene / ethanol solution is (5 to 15) g / 100mL.

[0043] In the toluene / ethanol solution, the volume ratio of toluene and ethanol is 1:1.

[0044] In the above technical solution, the sheath layer uses polypropylene as the main resin material, adds toughening agent, flame-retardant filler, and auxiliary agent for blending and extrusion molding. Polypropylene has good resistance to acid, alkali, salt solution, and most organic solvents, has good chemical resistance, is suitable for application in the complex environment of the automobile; has moderate melt index, is easy to extrude and mold, is suitable for continuous production of the sheath layer material; at the same time, polypropylene has high volume resistivity and dielectric strength, has good electrical insulation performance, and can meet the insulation requirements of the automobile wiring harness. The toughening agent can improve the brittleness of polypropylene, balance rigidity and toughness, improve the low-temperature performance, and improve the mechanical properties and durability of the prepared sheath layer.

[0045] Fillers such as aluminum hydroxide, magnesium hydroxide, etc. can be endothermic decomposition at 200-400℃, reduce the surface temperature of the material, decomposition of water vapor, dilute flammable gas; Decomposition products (aluminum oxide, magnesium oxide) can form a dense protective layer on the surface of the material, isolate oxygen and heat, promote the improvement of the flame retardant properties of polypropylene. And zinc oxide and magnesium hydroxide / aluminum hydroxide can reduce the amount of smoke when burning.

[0046] In the above technical solution, the polypropylene is modified by using benzoxazine-based compounds and maleic anhydride before use. The benzoxazine-based compound is obtained by reacting tris(2-aminoethoxy)borane and phenylphosphoryl dichloride to obtain a polyamino compound as an amine source, and then reacting with polyformaldehyde and p-allylphenol. The prepared benzoxazine-based compound has multiple functional double bonds, which can form an interpenetrating network with polypropylene under the action of initiator and heat energy, helping to improve the regularity of polypropylene molecules; and is grafted onto the polypropylene segment. Maleic anhydride is added during the process to participate in the reaction to introduce anhydride groups, thereby obtaining modified polypropylene. The introduction of benzoxazine structure into the polypropylene segment can effectively improve its thermal stability and flame retardant properties. Benzoxazine will undergo ring-opening polymerization when heated to form a network structure with high char yield, which can generate a stable carbon layer at high temperature, thereby blocking heat and flammable gases to achieve flame retardant effect. At the same time, the benzoxazine-based compound contains phosphoryl groups, which can produce phosphate after burning, thereby slowing down the decomposition rate of the material and further improving its flame retardant properties.

[0047] The maleic anhydride structure in the modified polypropylene can crosslink with metal ions in the filler (zinc oxide) and lubricant (calcium stearate, magnesium stearate) to form ionomers; this increases the melt viscosity, which can alleviate the problems of eccentricity and uneven distribution during extrusion, and improve the processing properties of polypropylene. The coordination bond between anhydride and metal ions generates a large number of dipoles, which polarize in an electric field, increase the trap level, and improve the volume resistivity and dielectric constant of the polypropylene material. At the same time, the intermolecular force is increased, which improves the mechanical properties of the polypropylene material.

[0048] If the toughening agent is also a maleic anhydride grafted copolymer, it can participate in the formation of ionomers, further improving the high temperature resistance, mechanical properties and insulation capacity of the prepared sheath layer material.

[0049] Compared with the prior art, the beneficial effects of the present application are as follows:

[0050] 1. The high-temperature-resistant wire harness for automobile described in the present application establishes a wire harness system for automobile by the cooperation of the wires, the terminals crimped on the core wire ends of the wires, the shielding rings crimped on the outer surfaces of the shielding layers of the reversely bent wires, and the sheath layers sleeved on the outer surfaces of the wires, to ensure the normal operation of the electrical system.

[0051] 2. The high-temperature-resistant wire harness for automobiles described in the application is formed by extrusion molding of a sheath layer with polypropylene as the main resin material, addition of toughening agent, flame-retardant filler and auxiliary agent; the polypropylene is modified with a benzoxazine-based compound and maleic anhydride before use. The benzoxazine-based compound is prepared by reaction of tris(2-aminoethoxy)borane, phenylphosphoryl dichloride, para-allyl phenol and polyformaldehyde. The benzoxazine structure is introduced into the polypropylene chain segment to improve its thermal stability and flame-retardant performance.

[0052] 3. The high-temperature-resistant wire harness for automobiles described in the application improves the processing performance of polypropylene by crosslinking the maleic anhydride structure in modified polypropylene with metal ions to form an ionomer. The acid anhydride forms a coordination bond with metal ions, generating a large number of dipoles, which are polarized in an electric field, increasing the trap level, improving the volume resistivity and dielectric constant of the polypropylene material. At the same time, the intermolecular force is increased, improving the mechanical properties of the polypropylene material. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the application will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the application.

[0054] In the following detailed description, the materials are dried before use;

[0055] Polypropylene: PP ST611M, melt index 1.8 g / 10 min (230℃ / 2.16 kg);

[0056] The sheath layer is annealed at 60℃ for 2h after cutting to eliminate internal stress;

[0057] The initiator is bis-tert-butyl peroxyisopropylbenzene;

[0058] In the toluene / ethanol solution, the volume ratio of toluene to ethanol is 1:1;

[0059] The toughening agent is a maleic anhydride grafted ethylene (90.95%)-methyl methacrylate (9%) copolymer with a melt index of 3.0 g / 10 min, a melting point of 101℃, a hardness of Shore D53 and a tensile strength of 9 MPa;

[0060] Polyolefin elastomer (POE), melt index 0.5 g / 10 min (190℃ / 2.16 kg);

[0061] The filler is a mixture of magnesium hydroxide, aluminum hydroxide and zinc oxide, with a mass ratio of 2:1:1; the magnesium hydroxide and aluminum hydroxide are 5000 mesh and industrial grade; the zinc oxide has a purity of 99.7% and a particle size of 5-8 μm;

[0062] The antioxidant is a mixture of antioxidant 1010 and antioxidant 168, with a mass ratio of 4:1;

[0063] The coupling agent is KH-550.

[0064] Embodiment 1: A method for preparing a high-temperature-resistant automobile wiring harness, comprising the following processes:

[0065] S1. Opening the wire: cutting the wire according to production requirements;

[0066] S2. Crimping: stripping the protective layer and sheath layer on the outer surface of the wire, reversely bending and trimming the shielding layer at the end of the wire to expose the core wire at the end of the wire;

[0067] Crimping a terminal at the end of the core wire of the wire and crimping a shielding ring at the end of the shielding layer to obtain a wire with a terminal;

[0068] S3. Sealing: sleeving a sheath layer on the outer surface of the wire with a terminal to obtain a wiring harness;

[0069] S4. Detection and packaging: conducting loop conduction, wire color, appearance, and size detection, and packaging after passing the detection;

[0070] The sheath layer in S3 is prepared by the following process:

[0071] (1) Mixing tris(2-aminoethoxy)borane and phenylphosphoryl dichloride, and reacting at 60°C for 8 h under nitrogen atmosphere protection; washing and drying to obtain a polyamino compound; the molar ratio of tris(2-aminoethoxy)borane to phenylphosphoryl dichloride is 2:1;

[0072] Dissolving the polyamino compound in a toluene / ethanol solution, adding para-allyl phenol and polyformaldehyde, and reacting at 80°C for 7 h; removing the solvent, washing, and drying to obtain a benzoxazine-based compound; the molar ratio of the polyamino compound, polyformaldehyde, and para-allyl phenol is 1:4.2:4; the ratio of the polyamino compound to the toluene / ethanol solution is 15 g / 100 mL;

[0073] (2) Mixing 50% of the total mass of the benzoxazine-based compound and the initiator with polypropylene, and reacting and extruding in an extruder, in the process, adding maleic anhydride and the remaining initiator to obtain modified polypropylene; the modified polypropylene is prepared from the following mass components: 100 parts of polypropylene, 5 parts of benzoxazine-based compound, 5 parts of maleic anhydride, and 0.1 part of initiator; the process conditions for reaction extrusion are: temperature 160°C and rotation speed 60 rpm;

[0074] (3) mixing the modified polypropylene with the toughening agent, the filler and the auxiliary agent at a rotating speed of 400 rpm for 15 min, melt-extruding at an extruding temperature of 180 ℃ and a rotating speed of 80 rpm, granulating to obtain polypropylene masterbatch; extruding the polypropylene masterbatch at an extruding temperature of 190 ℃ and a rotating speed of 80 rpm, water-cooling at 20 ℃ to obtain the sheath layer; the sheath layer comprises the following mass components: 85 parts of polypropylene, 5 parts of toughening agent, 10 parts of filler and 1.5 parts of auxiliary agent; the auxiliary agent comprises 0.5 part of antioxidant, 0.5 part of lubricant and 0.5 part of coupling agent; the lubricant is calcium stearate.

[0075] Example 2: a preparation method of a high-temperature-resistant automobile wire harness, comprising the following processes:

[0076] S1. opening the wire: cutting the wire according to the production requirement;

[0077] S2. crimping: peeling off the protective layer and the sheath layer on the outer surface of the wire, reversely bending and trimming the shielding layer at the end of the wire to expose the core wire at the end of the wire;

[0078] crimping a terminal at the end of the core wire of the wire and crimping a shielding ring at the end of the shielding layer to obtain a wire with terminal;

[0079] S3. sealing: sleeving a sheath layer on the outer surface of the wire with terminal to obtain a wire harness;

[0080] S4. detection and packaging: detecting the loop conduction, wire color, appearance and size, and packaging after passing the detection;

[0081] The sheath layer in S3 is prepared by the following process:

[0082] (1) mixing tris(2-aminoethoxy)borane and phenylphosphoryl dichloride, reacting at 65 ℃ for 7 h under the protection of nitrogen atmosphere; washing and drying to obtain a polyamino compound; the molar ratio of tris(2-aminoethoxy)borane to phenylphosphoryl dichloride is 2.2:1;

[0083] dissolving the polyamino compound in a toluene / ethanol solution, adding para-allyl phenol and polyformaldehyde, and reacting at 82 ℃ for 6 h; removing the solvent, washing and drying to obtain a benzoxazine-based compound; the molar ratio of the polyamino compound, the para-allyl phenol and the polyformaldehyde is 1:4.3:4.5; the ratio of the polyamino compound to the toluene / ethanol solution is 10 g / 100 mL;

[0084] (2) mixing 60% of the total mass of the benzoxazine-based compound and initiator with polypropylene, and reacting and extruding in an extruder, adding maleic anhydride and the remaining initiator in the process to obtain modified polypropylene; the modified polypropylene is prepared from the following mass components: 100 parts of polypropylene, 7 parts of a benzoxazine-based compound, 5 parts of maleic anhydride, and 0.2 parts of an initiator; the process conditions for reaction and extrusion are as follows: a temperature of 175°C and a rotation speed of 50 rpm;

[0085] (3) mixing the modified polypropylene with a toughening agent, a filler, and an auxiliary agent at a rotation speed of 300 rpm for 18 min, melt-extruding at an extrusion temperature of 200°C and a rotation speed of 60 rpm, and granulating to obtain polypropylene masterbatch; extruding the polypropylene masterbatch at an extrusion temperature of 200°C and a rotation speed of 60 rpm, and water-cooling at 25°C to obtain a sheath layer; the sheath layer comprises the following mass components: 80 parts of polypropylene, 8 parts of a toughening agent, 12 parts of a filler, and 3 parts of an auxiliary agent; the auxiliary agent comprises 1 part of an antioxidant, 1 part of a lubricant, and 1 part of a coupling agent; the lubricant is magnesium stearate.

[0086] Example 3: A method for preparing a high-temperature-resistant automobile wire harness, comprising the following processes:

[0087] S1. Opening the wire: cutting the wire according to production requirements;

[0088] S2. Crimping: peeling off the protective layer and the sheath layer on the outer surface of the wire, reversely bending and trimming the shielding layer at the end of the wire to expose the core wire at the end of the wire;

[0089] Crimping a terminal at the end of the core wire of the wire and crimping a shielding ring at the end of the shielding layer to obtain a wire with a terminal;

[0090] S3. Sealing: sleeving a sheath layer on the outer surface of the wire with a terminal to obtain a wire harness;

[0091] S4. Detection and packaging: detecting the loop conduction, wire color, appearance, and size, and packaging after passing the detection;

[0092] The sheath layer in S3 is prepared by the following process:

[0093] (1) mixing tris(2-aminoethoxy)borane and phenylphosphoryl dichloride, and reacting at 70°C for 6 h under the protection of a nitrogen atmosphere; washing and drying to obtain a polyamino compound; the molar ratio of tris(2-aminoethoxy)borane to phenylphosphoryl dichloride is 2.5:1;

[0094] The polyamino compound is dissolved in toluene / ethanol solution, polyformaldehyde and p-allyl phenol are added, and the temperature is raised to 85°C, and the reaction is carried out for 5 hours; the solvent is removed, washed and dried to obtain the benzoxazine-based compound; the molar ratio of the polyamino compound, polyformaldehyde and p-allyl phenol is 1:4.5:5; the ratio of the polyamino compound and toluene / ethanol solution is 15g / 100mL;

[0095] (2) The total mass of the benzoxazine-based compound and the initiator is 70% of the mixture of the polypropylene, which is placed in an extruder for reaction extrusion, and maleic anhydride and the remaining initiator are added during the process to obtain the modified polypropylene, and the modified polypropylene is obtained; the modified polypropylene is prepared from the following mass components: 100 parts of polypropylene, 10 parts of benzoxazine-based compound, 5 parts of maleic anhydride and 0.5 parts of initiator; the process conditions for reaction extrusion are: temperature 190°C, rotation speed 40rpm;

[0096] (3) The modified polypropylene is mixed with the toughening agent, the filler and the auxiliary agent at a rotation speed of 200rpm for 20 minutes, and is melt-extruded at an extrusion temperature of 220°C and a rotation speed of 40rpm to obtain the polypropylene master batch; the polypropylene master batch is extruded at an extrusion temperature of 210°C and a rotation speed of 40rpm, and is water-cooled at 30°C to obtain the sheath layer; the sheath layer comprises the following mass components: 80 parts of polypropylene, 10 parts of toughening agent, 10 parts of filler and 3.5 parts of auxiliary agent; the auxiliary agent comprises 1.5 parts of antioxidant, 1.0 part of lubricant and 1.0 part of coupling agent; the lubricant is calcium stearate.

[0097] Comparative Example 1: A method for preparing a high-temperature-resistant wire harness for automobiles, comprising the following processes:

[0098] The sheath layer in S3 is prepared by the following process:

[0099] (1) The tris(2-aminoethoxy)borane is dissolved in toluene / ethanol solution, polyformaldehyde and p-allyl phenol are added, and the temperature is raised to 80°C, and the reaction is carried out for 7 hours; the solvent is removed, washed and dried to obtain the benzoxazine-based compound; the molar ratio of the tris(2-aminoethoxy)borane, polyformaldehyde and p-allyl phenol is 1:3.2:3; the ratio of the tris(2-aminoethoxy)borane and toluene / ethanol solution is 15g / 100mL;

[0100] (2) The total mass of the benzoxazine-based compound and the initiator is 50% of the mixture of the polypropylene, which is placed in an extruder for reaction extrusion, and maleic anhydride and the remaining initiator are added during the process to obtain the modified polypropylene, and the modified polypropylene is obtained; the modified polypropylene is prepared from the following mass components: 100 parts of polypropylene, 5 parts of benzoxazine-based compound, 5 parts of maleic anhydride and 0.1 parts of initiator; the process conditions for reaction extrusion are: temperature 160°C, rotation speed 60rpm;

[0101] (3) The modified polypropylene is mixed with toughening agent, filler and auxiliary agent at a rotating speed of 400 rpm for 15 min, and then melt extruded at an extrusion temperature of 180 °C and a rotating speed of 80 rpm to obtain polypropylene masterbatch; the polypropylene masterbatch is extruded at an extrusion temperature of 190 °C and a rotating speed of 80 rpm to obtain a sheath layer; the sheath layer comprises the following components by mass: 85 parts of polypropylene, 5 parts of toughening agent, 10 parts of filler and 1.5 parts of auxiliary agent; the auxiliary agent comprises 0.5 part of antioxidant, 0.5 part of lubricant and 0.5 part of coupling agent; the lubricant is calcium stearate.

[0102] Other processes are the same as those in Example 1, and a wire harness is obtained.

[0103] Comparative Example 2: A preparation method of a high-temperature-resistant wire harness for automobile, comprising the following processes:

[0104] The sheath layer in S3 is prepared by the following process:

[0105] The total mass of 50% of propylene-based benzoxazinone (CAS: 1000771-60-7) and initiator is mixed with polypropylene, and then reaction extruded in an extruder; maleic anhydride and the remaining initiator are added during the process to obtain modified polypropylene; the modified polypropylene is prepared from the following components by mass: 100 parts of polypropylene, 5 parts of propylene-based benzoxazinone, 5 parts of maleic anhydride and 0.1 part of initiator; the process conditions of reaction extrusion are as follows: temperature 160 °C and rotating speed 60 rpm.

[0106] The modified polypropylene is mixed with toughening agent, filler and auxiliary agent at a rotating speed of 400 rpm for 15 min, and then melt extruded at an extrusion temperature of 180 °C and a rotating speed of 80 rpm to obtain polypropylene masterbatch; the polypropylene masterbatch is extruded at an extrusion temperature of 190 °C and a rotating speed of 80 rpm to obtain a sheath layer; the sheath layer comprises the following components by mass: 85 parts of polypropylene, 5 parts of toughening agent, 10 parts of filler and 1.5 parts of auxiliary agent; the auxiliary agent comprises 0.5 part of antioxidant, 0.5 part of lubricant and 0.5 part of coupling agent; the lubricant is calcium stearate.

[0107] Other processes are the same as those in Example 1, and a wire harness is obtained.

[0108] Comparative Example 3: A preparation method of a high-temperature-resistant wire harness for automobile, comprising the following processes:

[0109] The sheath layer in S3 is prepared by the following process:

[0110] Maleic anhydride and initiator are mixed with polypropylene, and then reaction extruded in an extruder to obtain modified polypropylene; the process conditions of reaction extrusion are as follows: temperature 160 °C and rotating speed 60 rpm.

[0111] The modified polypropylene, toughening agent, filler and auxiliary agent are mixed at a rotating speed of 400 rpm for 15 min, melt-extruded at an extrusion temperature of 180 ℃ and a rotating speed of 80 rpm, and pelletized to obtain polypropylene masterbatch; the polypropylene masterbatch is extruded at an extrusion temperature of 190 ℃ and a rotating speed of 80 rpm, and water-cooled at 20 ℃ to obtain the sheath layer; the sheath layer comprises the following mass components: 85 parts of polypropylene, 5 parts of toughening agent, 10 parts of filler and 1.5 parts of auxiliary agent; the auxiliary agent comprises 0.5 part of antioxidant, 0.5 part of lubricant and 0.5 part of coupling agent; the lubricant is calcium stearate.

[0112] Other processes are the same as those in Example 1, and a wire harness is obtained.

[0113] Comparative Example 4: A method for preparing a high-temperature-resistant automotive wire harness, comprising the following processes:

[0114] The sheath layer in S3 is prepared by the following process:

[0115] The modified polypropylene, toughening agent, filler and auxiliary agent are mixed at a rotating speed of 400 rpm for 15 min, melt-extruded at an extrusion temperature of 180 ℃ and a rotating speed of 80 rpm, and pelletized to obtain polypropylene masterbatch; the polypropylene masterbatch is extruded at an extrusion temperature of 190 ℃ and a rotating speed of 80 rpm, and water-cooled at 20 ℃ to obtain the sheath layer; the sheath layer comprises the following mass components: 85 parts of polypropylene, 5 parts of toughening agent (POE), 10 parts of filler and 1.5 parts of auxiliary agent; the auxiliary agent comprises 0.5 part of antioxidant, 0.5 part of lubricant and 0.5 part of coupling agent; the lubricant is calcium stearate.

[0116] Other processes are the same as those in Example 1, and a wire harness is obtained.

[0117] Experiment: The sheath layers and wire harnesses obtained in Examples 1-3 and Comparative Examples 1-4 are taken to prepare test samples, and the performance of the test samples is detected and the detection results are recorded:

[0118] Mechanical property test: The tensile property of the sheath layer sample is tested according to GB / T 1040.2 as the reference standard;

[0119] High-temperature resistance test: The sheath layer sample is placed in an oven at 150 ℃ for aging for 168 hours, and the tensile strength retention rate after aging is tested;

[0120] Flame retardant property test: The vertical combustion test of the sheath layer sample (125 mm x 13 mm x 3 mm) is performed according to UL 94-V as the reference standard;

[0121] Insulation property test: The volume resistivity of the sheath layer sample is detected at a voltage of 500 V by using a high resistance meter according to GB / T 1410 as the reference standard; the test conditions are 23±2 ℃ and 50±5% RH;

[0122] The breakdown voltage of the sample was detected with GB / T 1408.1 as a reference standard, and the dielectric strength (kV / mm) was calculated, and the voltage rise rate was 1 kV / s.

[0123] The detection results are as follows:

[0124]

[0125] According to the data in the above table, the following conclusions can be clearly obtained:

[0126] The sheath layer obtained in Examples 1-3 is compared with the sheath layer obtained in Comparative Examples 1-4, and the detection results show that,

[0127] Compared with Comparative Example 4, the sheath layer obtained in Examples 1-3 has higher tensile strength data, better performance in high temperature and combustion experiments, and higher volume resistivity and dielectric strength data. This fully shows that the present application improves the mechanical properties, flame retardant properties, insulation properties and high temperature stability of the prepared sheath layer material.

[0128] Compared with Example 1, the preparation method of the benzoxazine-based compound and the components used in Comparative Example 1 are different; the benzoxazine-based compound in Comparative Example 2 is replaced by propenyl benzoxazinone; the polypropylene modified by maleic anhydride in Comparative Example 3; and the polypropylene in Comparative Example 4 is not modified, and the selection of the toughening agent is different. The tensile strength data of the sheath layer obtained in Comparative Examples 1-4 decreases, and the performance in high temperature and combustion experiments is relatively poor, and the volume resistivity and dielectric strength data decrease. It can be seen that the setting of the preparation process of the sheath layer material in the present application can promote the comprehensive improvement of its mechanical properties, flame retardant properties, insulation properties and high temperature stability.

[0129] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

Claims

1. A method of manufacturing a wire harness for an automobile, characterized by: The process comprises the following steps: S1. Cutting: cutting the conductor according to the production requirement; S2. Crimping: stripping the protective layer and the sheath layer on the outer surface of the conductor, reversely bending and trimming the shielding layer at the end of the conductor to expose the core wire at the end of the conductor; Crimping a terminal at the end of the core wire of the conductor to obtain a conductor with a terminal; S3. Sealing: sleeving a sheath layer on the outer surface of the conductor with the terminal to obtain a wire harness; S4. Detection and packaging: detecting the loop conduction, wire color, appearance and size, and packaging after passing the detection; The sheath layer is prepared by the following process: Mixing polypropylene, toughening agent, filler and auxiliary agent, melt extruding, granulating to obtain polypropylene masterbatch; extruding the polypropylene masterbatch, cooling to obtain the sheath layer; The polypropylene is modified by using a benzoxazine-based compound and maleic anhydride before use, and the specific process is as follows: Mixing 50-70% of the total mass of the benzoxazine-based compound and initiator with polypropylene, and reacting and extruding in an extruder, and adding maleic anhydride and the remaining initiator during the process to obtain modified polypropylene; The benzoxazine-based compound is prepared by the following process: Mixing tris(2-aminoethoxy)borane and phenylphosphoryl dichloride, and reacting at 60-70℃ for 6-8h under nitrogen atmosphere protection; washing and drying to obtain a polyamino compound; Dissolving the polyamino compound in a toluene / ethanol solution, adding para-allyl phenol and polyformaldehyde, and reacting at 80-85℃ for 5-7h; removing the solvent, washing and drying to obtain the benzoxazine-based compound; The molar ratio of tris(2-aminoethoxy)borane and phenylphosphoryl dichloride is (2.0-2.5):1; The molar ratio of the polyamino compound, polyformaldehyde and para-allyl phenol is 1:(4.2-4.5):(4-5); The auxiliary agent comprises an antioxidant, a lubricant and a coupling agent; the lubricant is one of calcium stearate and magnesium stearate; The toughening agent is one or a mixture of more than one of polyolefin elastomer, methyl methacrylate-butadiene-styrene terpolymer and maleic anhydride grafted ethylene-methyl methacrylate copolymer; The filler is a mixture of more than one of magnesium hydroxide, aluminum hydroxide, aluminum-magnesium hydrotalcite, talcum powder and zinc oxide.

2. The method of claim 1, wherein: The sheath layer comprises the following mass components: 70-85 parts of polypropylene, 5-10 parts of toughening agent, 5-15 parts of filler and 1.5-3.5 parts of auxiliary agent.

3. The method of claim 2, wherein: The auxiliary agent comprises 0.5-1.5 parts of antioxidant, 0.5-1.0 parts of lubricant and 0.5-1.0 parts of coupling agent.

4. A wire harness for an automobile, characterized by: The wire harness for automobiles is prepared by the preparation method of any one of claims 1-3.

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