Flame-retardant aging-resistant automotive wire harness and preparation method thereof

Abstract

The invention discloses a flame-retardant and aging-resistant vehicle wire harness and a method thereof, and the preparation method of the flame-retardant and aging-resistant vehicle wire harness comprises the following steps: mutually twisting a plurality of tinned copper wires to form a wire core body; coating an insulating layer on the conductor core body, and then coating an aluminum foil layer on the outer side of the insulating layer to obtain a single-strand wire harness; the method comprises the following steps: taking a plurality of single-strand wire harnesses, separating the single-strand wire harnesses from one another through linings, coating a sheath layer on the outer side of the single-strand wire harnesses, sleeving a corrugated pipe and a winding adhesive tape on the outer side of the sheath layer, and installing and fixing terminals at two ends to obtain a finished product of the flame-retardant and aging-resistant wire harness for the vehicle; the materials of the sheath layer adopt polypropylene, ethylene-octylene copolymer, modified filler and other components according to a specific ratio, so that the comprehensive mechanical property, flame retardant property and aging resistance of the wire harness are synergistically improved, and finally the balance and optimization of various key performance indexes of the vehicle wire harness in a harsh use environment are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile wiring harnesses, and particularly relates to a flame-retardant and aging-resistant automobile wiring harness and a preparation method thereof. Background Art

[0002] The wiring harness is the network backbone of a vehicle's electrical circuits; without it, there would be no circuit. A wiring harness is a component consisting of copper-stamped contact terminals (connectors) crimped onto wires and cables, then covered with plastic-molded insulation or a metal casing, forming a bundled assembly that connects the circuits. The wiring harness industry chain encompasses wires and cables, connectors, processing equipment, wiring harness manufacturing, and downstream application industries. Wiring harnesses are widely used in automobiles, household appliances, computers and communications equipment, and various electronic instruments and meters.

[0003] In order to improve the heat aging resistance and flame retardancy of automotive wiring harnesses on the market today, researchers often add a large amount of halogen-free solid flame retardants such as aluminum hydroxide or magnesium hydroxide to the outer sheath formula of the wiring harness, and the amount usually needs to be greater than the amount of the matrix resin, which greatly reduces the overall tensile strength and elongation at break of the material. The filling of a large amount of solid inorganic matter is not only incompatible with the resin system, but also causes the tear resistance of the wiring harness to deteriorate. In order to solve this problem, people have proposed the method of using composite organic phosphorus and nitrogen flame retardants. Although the addition amount of phosphorus and nitrogen flame retardants is significantly lower than that of inorganic flame retardants, due to the existence of compatibility and other issues, its negative impact on the comprehensive mechanical properties of the wiring harness cannot be ignored.

[0004] Chinese patent application CN115781778A discloses a method for preparing an aging-resistant harness protective cover, comprising the following steps: Step 1, placing a certain amount of silicone rubber between a front roller and a rear roller for extrusion and kneading; Step 2, conveying a certain amount of linear low-density polyethylene, ultra-molecular-weight polyethylene, polysulfone, low-melting-point glass powder, white carbon black, mica, silicone oil, fumed aluminum hydroxide, diisopropylbenzene peroxide, vinyltriethoxysilane, dibutyltin dilaurate, platinum catalyst, foaming agent, flame retardant, vulcanizing agent and compatibilizer between the front roller and the rear roller for further extrusion and kneading with the silicone rubber; Step 3, transferring the extruded and kneaded material layer to a hot vulcanizer for processing and molding; This invention does not require manual operation during the material kneading process and is easy to use. However, this patent mainly improves the structure of the internal mixer so that the raw materials in the layered material can be mixed more evenly and conveniently operated, and its improvement on the flame retardancy and aging resistance of the material itself is limited. Chinese patent application CN106084433A discloses a high-strength, aging-resistant sheath material for wiring harnesses and its preparation method. The material is composed of the following components in parts by weight: 20-30 parts EVA resin, 20-40 parts cis-polyisoprene, 5-10 parts alumina, 10-20 parts polyethylene, 1-3 parts sodium dodecylbenzenesulfonate, 10-15 parts dioctyl terephthalate, 1-3 parts polyvinyl alcohol, 1-3 parts magnesium hydroxide, 2-3 parts diethylenetriamine, 1-4 parts white oil, 1-2 parts sodium bicarbonate, and 20-40 parts water. The invention also provides a method for manufacturing the sheath material, comprising the steps of grinding, stirring, and heating and drying the above components to obtain a material, followed by roller refining, plasticizing, and naturally cooling and pressing the material. The material produced by this method exhibits excellent corrosion and heat resistance, is simple to prepare, and uses readily available raw materials, making it promising for widespread adoption. However, the patent incorporates a relatively low level of flame retardant, and its flame retardant properties need improvement.

[0005] In summary, it is of great significance to develop an automotive wiring harness with good mechanical properties, high flame retardant properties and excellent aging resistance in this field. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the present invention aims to provide a flame-retardant and aging-resistant automotive wiring harness and a preparation method thereof.

[0007] To achieve the above object, the present invention provides the following technical solutions: A method for preparing a flame-retardant and aging-resistant automotive wiring harness comprises the following steps: Multiple tinned copper wires are twisted together to form a conductor core; an insulation layer is coated on the conductor core, and then an aluminum foil layer is coated on the outside of the insulation layer to obtain a single-strand wire harness; multiple single-strand wire harnesses are taken, separated by linings, and a sheath layer is coated on the outside of the multiple single-strand wire harnesses, and then a corrugated tube is placed on the outside of the sheath layer, and then an adhesive tape is wrapped around it, and fixed terminals are installed at both ends to obtain a flame-retardant and aging-resistant automotive wire harness product; The material of the sheath layer is composed of the following raw materials in parts by weight: 80-90 parts of polypropylene, 20-30 parts of ethylene-octene copolymer, 25-35 parts of modified filler, 10-15 parts of compatibilizer, 2-3 parts of antioxidant, and 1-2 parts of lubricant.

[0008] In this invention, the sheath layer material is based on polypropylene and ethylene-octene copolymer. By introducing a multifunctional modified montmorillonite filler with a specific structure and combining it with a compatibilizer, antioxidant, and lubricant, the flame retardancy and heat aging resistance of the wiring harness can be significantly improved while maintaining good mechanical properties. The design of this modified filler takes into account inorganic flame retardancy, synergistic flame retardancy with organic phosphorus and nitrogen, and interfacial compatibility with the polymer matrix. This overcomes the problems of mechanical performance degradation caused by the addition of large amounts of inorganic flame retardants and the poor compatibility of organic phosphorus and nitrogen flame retardants, providing an effective technical approach for the preparation of automotive wiring harnesses with excellent overall performance.

[0009] Preferably, the preparation method of the modified filler comprises the following steps: S1, montmorillonite was added to deionized water, followed by sodium lauryl sulfate, and after stirring and dispersing evenly, zinc sulfate solution was added, and stirred at room temperature for 3-4 hours, followed by dropwise addition of ammonium molybdate solution, and the pH was controlled at 8-9. After the addition was completed, the mixture was stirred, aged, filtered, washed, and dried to obtain a composite montmorillonite; S2, adding the composite montmorillonite prepared in step S1 to an ethanol aqueous solution, then adding vinyltriethoxysilane, stirring and reacting, filtering, washing, and drying after the reaction is completed to obtain vinylated montmorillonite; S3, adding the vinylated montmorillonite prepared in step S2 to toluene, followed by adding 2-mercaptobenzimidazole carboxylic acid and azobisisobutyronitrile, and reacting at a constant temperature. After the reaction is completed, filtering, washing, and drying to obtain an organic montmorillonite; S4. Add the organized montmorillonite in step S3 to DMF, then add EDC and NHS, stir at room temperature for 20-30 minutes, then add bis(4-aminophenyl) phosphate, and heat to react. After the reaction is completed, filter, wash, and dry to obtain a modified filler.

[0010] Preferably, the mass ratio of the composite montmorillonite, deionized water, sodium lauryl sulfate, zinc sulfate solution, and ammonium molybdate solution in step S1 is 40-50:900-1000:0.3-0.5:60-80:50-70, the mass concentration of the zinc sulfate solution is 10-15%, and the mass concentration of the ammonium molybdate solution is 10-15%.

[0011] Preferably, the aging temperature in step S1 is 50-60° C. and the aging time is 6-8 hours.

[0012] In the present invention, the modified filler uses montmorillonite as the matrix material. Montmorillonite is a natural layered silicate mineral with a nano-scale lamellar structure and a large specific surface area, which is easy to be intercalated and surface modified. First, sodium dodecyl sulfate is used to reduce the surface tension of the montmorillonite particles, helping them to better disperse in deionized water and reduce agglomeration. Then, zinc molybdate is generated in situ on the montmorillonite surface, which promotes the formation of a carbon layer when the material burns, isolates oxygen and heat, and suppresses the generation of toxic smoke. The nano-lamellar structure of the montmorillonite and the in-situ generated zinc molybdate can play a synergistic flame retardant role, effectively improving the flame retardancy of the material and reducing smoke release during combustion. At the same time, the in-situ generation can make these flame retardant components more evenly distributed, help to regulate the particle size and dispersion state of the zinc molybdate, and enhance its combination with the montmorillonite, laying a good foundation for subsequent modification and the final uniform dispersion of the filler in the matrix, thereby achieving an effective flame retardant effect at a lower addition amount.

[0013] Preferably, the mass fraction of ethanol in the ethanol aqueous solution in step S2 is 70-80%, the mass ratio of montmorillonite to vinyltriethoxysilane is 50-60:4-6, the stirring reaction temperature is 60-70° C., and the time is 2-3 h.

[0014] In the present invention, vinyltriethoxysilane is used to treat the surface of the composite filler, and vinyl functional groups are successfully introduced. On the one hand, the agglomeration of the filler in the organic matrix is reduced, and on the other hand, active reaction sites are provided for subsequent reactions, which is an important bridge for realizing the multifunctionalization of the filler.

[0015] Preferably, in step S3, the mass ratio of vinyl montmorillonite, 2-mercaptobenzimidazole carboxylic acid, and azobisisobutyronitrile is 50-60:4-6:0.3-0.5, and the isothermal reaction temperature is 80-90° C. and the reaction time is 1-2 h.

[0016] In the present invention, 2-mercaptobenzimidazole carboxylic acid is successfully grafted onto the surface of vinylated montmorillonite using azobisisobutyronitrile as an initiator. The benzimidazole heterocycle contained in the 2-mercaptobenzimidazole structure gives the modified filler excellent thermal stability and antioxidant properties, which helps to improve the long-term service life and performance stability of the wiring harness sheath in harsh environments such as high temperatures. At the same time, the benzimidazole group has good ultraviolet absorption ability and light stability. It can absorb ultraviolet energy and convert it into heat energy or other harmless forms of energy through intramolecular rearrangement, thereby reducing the direct damage of ultraviolet rays to the polymer matrix. In addition, the carboxyl polar group in 2-mercaptobenzimidazole carboxylic acid can further improve the interaction with the polymer and provide reactive sites for subsequent reactions, thereby enhancing the chemical modification potential of the filler.

[0017] Preferably, the mass ratio of the organized montmorillonite, bis(4-aminophenyl)phosphate, EDC, and NHS in step S4 is 50-60:2.5-4:4-6:2.5-3.5.

[0018] Preferably, the heating reaction in step S4 is carried out at a temperature of 70-80° C. and for a time of 2-3 h.

[0019] In the present invention, bis(4-aminophenyl) phosphate is grafted onto the surface of the organic montmorillonite through an amidation reaction, and the phosphorus element and aromatic amine structure are successfully introduced. The phosphate group, as a highly efficient flame retardant element, can significantly improve the flame retardant properties of the material through the dual mechanisms of promoting carbonization in the condensed phase and capturing free radicals in the gas phase. The zinc molybdate generated in situ in the modified filler forms an inorganic-organic synergistic flame retardant system; and the presence of the aromatic amine structure can further enhance the thermal stability of the material, ensuring that the final wire harness sheath has excellent flame retardancy while also maintaining good heat aging resistance.

[0020] Preferably, the compatibilizer is maleic anhydride grafted polypropylene; the antioxidant is one or more of antioxidant 1010, antioxidant 1098, and antioxidant 168; and the lubricant includes one or more of zinc stearate, calcium stearate, and erucamide.

[0021] The present invention also protects a flame-retardant and aging-resistant automotive wiring harness prepared by the method described above.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) The flame-retardant and aging-resistant automotive wiring harness provided by the present invention has a sheath layer material made of components such as polypropylene, ethylene-octene copolymer, and modified fillers in a specific ratio, and the core component modified filler is subjected to a sophisticated multi-step composite and surface functionalization treatment, thereby synergistically improving the comprehensive mechanical properties, flame retardant properties, and aging resistance of the wiring harness, effectively overcoming the problems of low tensile strength and poor elongation at break caused by the addition of a large amount of inorganic flame retardants in traditional wiring harnesses, and ultimately achieving the balance and optimization of various key performance indicators of automotive wiring harnesses under harsh usage environments.

[0023] (2) The flame-retardant and aging-resistant automotive wiring harness provided by the present invention is added with a modified filler prepared by a specific method, with montmorillonite as the matrix material, and a nano-composite filler is generated by in-situ reaction of montmorillonite with zinc sulfate and ammonium molybdate. The introduced molybdate not only has excellent carbonization catalysis and smoke suppression properties, and preliminarily constructs the flame retardant system of the material, but also improves the dispersion state of montmorillonite in the matrix; then, the composite montmorillonite is surface-vinylated using vinyltriethoxysilane, and then, by grafting 2-mercaptobenzimidazole carboxylic acid, the stable imidazole heterocycle in its molecular structure is utilized to give the material excellent thermal stability and antioxidant and aging resistance, and produce a synergistic effect with other flame retardant components to further enhance the flame retardant effect; finally, bis(4-aminophenyl) phosphate is introduced, and the overall flame retardant efficiency of the material is greatly improved by virtue of the flame retardant properties of the phosphorus element in its molecular structure and the stability of the aromatic structure. Through specific methods and raw materials, the filler can not only be evenly dispersed in the resin matrix and form a strong interface bond with it, but more importantly, it integrates a variety of high-efficiency flame retardant and stabilizing functional groups, so that the final wire harness sheath material can exhibit excellent flame retardancy, outstanding aging resistance and good mechanical properties even at a relatively low filler addition. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0025] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from commercially purchased raw materials.

[0026] In the embodiment of the present invention, the particle size of the montmorillonite is 325-400 mesh; the polypropylene is homopolymer polypropylene from Maoming Petrochemical, with a brand name of T03; and the ethylene-octene copolymer is Dow 8137 from the United States.

[0027] Example 1

[0028] A method for preparing a flame-retardant and aging-resistant automotive wiring harness comprises the following steps: Multiple tinned copper wires are twisted together to form a conductor core; an insulation layer is coated on the conductor core, and then an aluminum foil layer is coated on the outside of the insulation layer to obtain a single-strand wire harness; multiple single-strand wire harnesses are taken, separated by linings, and a sheath layer is coated on the outside of the multiple single-strand wire harnesses, and then a corrugated tube is placed on the outside of the sheath layer, and then an adhesive tape is wrapped around it, and fixed terminals are installed at both ends to obtain a flame-retardant and aging-resistant automotive wire harness product; The material of the sheath layer is composed of the following raw materials in parts by weight: 85 parts of polypropylene, 25 parts of ethylene-octene copolymer, 30 parts of modified filler, 13 parts of maleic anhydride grafted polypropylene, 2.5 parts of antioxidant 1010, and 1.5 parts of zinc stearate; The preparation method of the modified filler comprises the following steps: S1, 45g of montmorillonite was added to 950g of deionized water, followed by 0.4g of sodium lauryl sulfate. After stirring and dispersing evenly, 70g of 13% zinc sulfate solution was added, and stirred at room temperature for 3.5h. Subsequently, 60g of 13% ammonia molybdate solution was added dropwise, and the pH was controlled at 8.5. After the addition was completed, the mixture was stirred for 1h, aged at 55°C for 7h, and then filtered, washed, and dried to obtain a composite montmorillonite; S2, adding 55g of the composite montmorillonite obtained in step S1 to 800mL of an ethanol aqueous solution (the mass fraction of ethanol is 75%), then adding 5g of vinyltriethoxysilane, stirring and reacting at 65°C for 2.5h. After the reaction is completed, filtering, washing, and drying to obtain vinylated montmorillonite; S3, adding 55g of vinylated montmorillonite in step S2 to 800mL of toluene, followed by adding 5g of 2-mercaptobenzimidazole carboxylic acid and 0.4g of azobisisobutyronitrile, and reacting at 85°C under a nitrogen atmosphere for 1-2h. After the reaction is completed, filtering, washing, and drying to obtain an organic montmorillonite; S4. Add 55 g of the organized montmorillonite in step S3 to 1 L of DMF, then add 5 g of EDC and 3 g of NHS. After stirring at room temperature for 25 min, add 3.5 g of bis(4-aminophenyl)phosphate, and react at 75° C. under a nitrogen atmosphere for 2.5 h. After the reaction is completed, filter, wash, and dry to obtain a modified filler.

[0029] The preparation method of the masterbatch of the sheath layer material is as follows: weigh the raw materials according to the formula, add polypropylene, ethylene-octene copolymer, modified filler, maleic anhydride grafted polypropylene, antioxidant 1010, and zinc stearate into a high-speed mixer, mix for 10 minutes, and then add the mixture into a twin-screw extruder for extrusion and granulation at 210°C to obtain the sheath layer masterbatch.

[0030] Example 2

[0031] A method for preparing a flame-retardant and aging-resistant automotive wiring harness comprises the following steps: Multiple tinned copper wires are twisted together to form a conductor core; an insulation layer is coated on the conductor core, and then an aluminum foil layer is coated on the outside of the insulation layer to obtain a single-strand wire harness; multiple single-strand wire harnesses are taken, separated by linings, and a sheath layer is coated on the outside of the multiple single-strand wire harnesses, and then a corrugated tube is placed on the outside of the sheath layer, and then an adhesive tape is wrapped around it, and fixed terminals are installed at both ends to obtain a flame-retardant and aging-resistant automotive wire harness product; The material of the sheath layer is composed of the following raw materials in parts by weight: Polypropylene 90 parts, ethylene-octene copolymer 30 parts, modified filler 35 parts, maleic anhydride grafted polypropylene 15 parts, antioxidant 1010 3 parts, erucamide 2 parts; The preparation method of the modified filler comprises the following steps: S1, 40g of montmorillonite was added to 900g of deionized water, followed by 0.3g of sodium lauryl sulfate. After stirring and dispersing evenly, 60g of a 10% zinc sulfate solution was added, and the mixture was stirred at room temperature for 3h. Subsequently, 50g of a 10% ammonium molybdate solution was added dropwise, and the pH was controlled at 8. After the addition was completed, the mixture was stirred for 1h, aged at 50°C for 8h, and then filtered, washed, and dried to obtain a composite montmorillonite; S2, adding 50g of the composite montmorillonite obtained in step S1 to 800mL of an ethanol aqueous solution (the mass fraction of ethanol is 70%), then adding 4g of vinyltriethoxysilane, stirring and reacting at 60°C for 3h. After the reaction is completed, filtering, washing, and drying to obtain vinylated montmorillonite; S3, adding 50g of vinylated montmorillonite in step S2 to 800mL of toluene, followed by adding 4g of 2-mercaptobenzimidazole carboxylic acid and 0.3g of azobisisobutyronitrile, and reacting at 80°C under a nitrogen atmosphere for 2h. After the reaction is completed, filtering, washing, and drying to obtain an organic montmorillonite; S4. Add 50 g of the organized montmorillonite in step S3 to 1 L of DMF, then add 4 g of EDC and 2.5 g of NHS. After stirring at room temperature for 20 min, add 2.5 g of bis(4-aminophenyl)phosphate, and react at 70° C. under a nitrogen atmosphere for 3 h. After the reaction is completed, filter, wash, and dry to obtain a modified filler.

[0032] The preparation method of the masterbatch of the sheath layer material is as follows: weigh the raw materials according to the formula, add polypropylene, ethylene-octene copolymer, modified filler, maleic anhydride grafted polypropylene, antioxidant 1010, and erucamide into a high-speed mixer, mix for 10 minutes, and then add into a twin-screw extruder for extrusion and granulation at 210°C to obtain the sheath layer masterbatch.

[0033] Example 3

[0034] A method for preparing a flame-retardant and aging-resistant automotive wiring harness comprises the following steps: Multiple tinned copper wires are twisted together to form a conductor core; an insulation layer is coated on the conductor core, and then an aluminum foil layer is coated on the outside of the insulation layer to obtain a single-strand wire harness; multiple single-strand wire harnesses are taken, separated by linings, and a sheath layer is coated on the outside of the multiple single-strand wire harnesses, and then a corrugated tube is placed on the outside of the sheath layer, and then an adhesive tape is wrapped around it, and fixed terminals are installed at both ends to obtain a flame-retardant and aging-resistant automotive wire harness product; The material of the sheath layer is composed of the following raw materials in parts by weight: 80 parts of polypropylene, 20 parts of ethylene-octene copolymer, 25 parts of modified filler, 10 parts of maleic anhydride grafted polypropylene, 2 parts of antioxidant 1010, 1 part of calcium stearate; The preparation method of the modified filler comprises the following steps: S1, 50g of montmorillonite was added to 1000g of deionized water, followed by adding 0.5g of sodium lauryl sulfate, and after stirring and dispersing evenly, 80g of a 15% zinc sulfate solution was added, and stirred at room temperature for 4h, followed by dropwise addition of 70g of a 15% ammonium molybdate solution, and the pH was controlled at 9. After the addition was completed, the mixture was stirred for 1h, aged at 60°C for 6h, and then filtered, washed, and dried to obtain a composite montmorillonite; S2, adding 60g of the composite montmorillonite obtained in step S1 to 800mL of an ethanol aqueous solution (the mass fraction of ethanol is 80%), then adding 6g of vinyltriethoxysilane, stirring and reacting at 70°C for 2h. After the reaction is completed, filtering, washing, and drying to obtain vinylated montmorillonite; S3, adding 60g of vinylated montmorillonite in step S2 to 800mL of toluene, followed by adding 6g of 2-mercaptobenzimidazole carboxylic acid and 0.5g of azobisisobutyronitrile, and reacting at 90°C under a nitrogen atmosphere for 1h. After the reaction is completed, filtering, washing, and drying to obtain an organic montmorillonite; S4. Add 60 g of the organized montmorillonite in step S3 to 1 L of DMF, then add 6 g of EDC and 3.5 g of NHS. After stirring at room temperature for 30 min, add 4 g of bis(4-aminophenyl)phosphate, and react at 80° C. under a nitrogen atmosphere for 2 h. After the reaction is completed, filter, wash, and dry to obtain a modified filler.

[0035] The preparation method of the masterbatch of the sheath layer material is as follows: weigh the raw materials according to the formula, add polypropylene, ethylene-octene copolymer, modified filler, maleic anhydride grafted polypropylene, antioxidant 1010, and calcium stearate into a high-speed mixer, mix for 10 minutes, and then add it into a twin-screw extruder for extrusion and granulation at 210°C to obtain the sheath layer masterbatch.

[0036] Comparative Example 1

[0037] A method for preparing a flame-retardant and aging-resistant automotive wiring harness comprises the following steps: Multiple tinned copper wires are twisted together to form a conductor core; an insulation layer is coated on the conductor core, and then an aluminum foil layer is coated on the outside of the insulation layer to obtain a single-strand wire harness; multiple single-strand wire harnesses are taken, separated by linings, and a sheath layer is coated on the outside of the multiple single-strand wire harnesses, and then a corrugated tube is placed on the outside of the sheath layer, and then an adhesive tape is wrapped around it, and fixed terminals are installed at both ends to obtain a flame-retardant and aging-resistant automotive wire harness product; The material of the sheath layer is composed of the following raw materials in parts by weight: 85 parts of polypropylene, 25 parts of ethylene-octene copolymer, 30 parts of modified filler, 13 parts of maleic anhydride grafted polypropylene, 2.5 parts of antioxidant 1010, and 1.5 parts of zinc stearate; The preparation method of the modified filler comprises the following steps: S1. Add 55 g of montmorillonite to 800 mL of ethanol aqueous solution (the mass fraction of ethanol is 75%), then add 5 g of vinyltriethoxysilane, and stir at 65°C for 2.5 h. After the reaction is completed, filter, wash, and dry to obtain vinyl montmorillonite; S2, adding 55g of vinylated montmorillonite in step S1 to 800mL of toluene, followed by adding 5g of 2-mercaptobenzimidazole carboxylic acid and 0.4g of azobisisobutyronitrile, and reacting at 85°C under a nitrogen atmosphere for 1-2h. After the reaction is completed, filtering, washing, and drying to obtain an organic montmorillonite; S3. Add 55 g of the organized montmorillonite in step S2 to 1 L of DMF, then add 5 g of EDC and 3 g of NHS. After stirring at room temperature for 25 min, add 3.5 g of bis(4-aminophenyl)phosphate, and react at 75° C. under a nitrogen atmosphere for 2.5 h. After the reaction is completed, filter, wash, and dry to obtain a modified filler.

[0038] The preparation method of the masterbatch of the sheath layer material is as follows: weigh the raw materials according to the formula, add polypropylene, ethylene-octene copolymer, modified filler, maleic anhydride grafted polypropylene, antioxidant 1010, and zinc stearate into a high-speed mixer, mix for 10 minutes, and then add the mixture into a twin-screw extruder for extrusion and granulation at 210°C to obtain the sheath layer masterbatch.

[0039] Compared with Example 1, zinc molybdate is not introduced into the modified filler.

[0040] Comparative Example 2

[0041] A method for preparing a flame-retardant and aging-resistant automotive wiring harness comprises the following steps: Multiple tinned copper wires are twisted together to form a conductor core; an insulation layer is coated on the conductor core, and then an aluminum foil layer is coated on the outside of the insulation layer to obtain a single-strand wire harness; multiple single-strand wire harnesses are taken, separated by linings, and a sheath layer is coated on the outside of the multiple single-strand wire harnesses, and then a corrugated tube is placed on the outside of the sheath layer, and then an adhesive tape is wrapped around it, and fixed terminals are installed at both ends to obtain a flame-retardant and aging-resistant automotive wire harness product; The material of the sheath layer is composed of the following raw materials in parts by weight: 85 parts of polypropylene, 25 parts of ethylene-octene copolymer, 30 parts of modified filler, 13 parts of maleic anhydride grafted polypropylene, 2.5 parts of antioxidant 1010, and 1.5 parts of zinc stearate; The preparation method of the modified filler comprises the following steps: S1, 45g of montmorillonite was added to 950g of deionized water, followed by 0.4g of sodium lauryl sulfate. After stirring and dispersing evenly, 70g of 13% zinc sulfate solution was added, and stirred at room temperature for 3.5h. Subsequently, 60g of 13% ammonia molybdate solution was added dropwise, and the pH was controlled at 8.5. After the addition was completed, the mixture was stirred for 1h, aged at 55°C for 7h, and then filtered, washed, and dried to obtain a composite montmorillonite; S2, adding 55g of the composite montmorillonite obtained in step S1 to 800mL of an ethanol aqueous solution (the mass fraction of ethanol is 75%), then adding 5g of vinyltriethoxysilane, stirring and reacting at 65°C for 2.5h. After the reaction is completed, filtering, washing, and drying to obtain vinylated montmorillonite; S3. Add 55 g of vinylated montmorillonite in step S2 to 800 mL of toluene, and then add 5 g of 2-mercaptobenzimidazole carboxylic acid and 0.4 g of azobisisobutyronitrile. React at 85° C. under a nitrogen atmosphere for 1-2 h. After the reaction is completed, filter, wash, and dry to obtain a modified filler.

[0042] The preparation method of the masterbatch of the sheath layer material is as follows: weigh the raw materials according to the formula, add polypropylene, ethylene-octene copolymer, modified filler, maleic anhydride grafted polypropylene, antioxidant 1010, and zinc stearate into a high-speed mixer, mix for 10 minutes, and then add the mixture into a twin-screw extruder for extrusion and granulation at 210°C to obtain the sheath layer masterbatch.

[0043] Compared with Example 1, no bis(4-aminophenyl)phosphate was introduced on the modified filler.

[0044] Comparative Example 3

[0045] A method for preparing a flame-retardant and aging-resistant automotive wiring harness comprises the following steps: Multiple tinned copper wires are twisted together to form a conductor core; an insulation layer is coated on the conductor core, and then an aluminum foil layer is coated on the outside of the insulation layer to obtain a single-strand wire harness; multiple single-strand wire harnesses are taken, separated by linings, and a sheath layer is coated on the outside of the multiple single-strand wire harnesses, and then a corrugated tube is placed on the outside of the sheath layer, and then an adhesive tape is wrapped around it, and fixed terminals are installed at both ends to obtain a flame-retardant and aging-resistant automotive wire harness product; The material of the sheath layer is composed of the following raw materials in parts by weight: 85 parts of polypropylene, 25 parts of ethylene-octene copolymer, 30 parts of modified filler, 13 parts of maleic anhydride grafted polypropylene, 2.5 parts of antioxidant 1010, and 1.5 parts of zinc stearate; The preparation method of the modified filler comprises the following steps: S1, 45g of montmorillonite was added to 950g of deionized water, followed by 0.4g of sodium lauryl sulfate. After stirring and dispersing evenly, 70g of 13% zinc sulfate solution was added, and stirred at room temperature for 3.5h. Subsequently, 60g of 13% ammonia molybdate solution was added dropwise, and the pH was controlled at 8.5. After the addition was completed, the mixture was stirred for 1h, aged at 55°C for 7h, and then filtered, washed, and dried to obtain a composite montmorillonite; S2, adding 55g of the composite montmorillonite obtained in step S1 to 800mL of an ethanol aqueous solution (the mass fraction of ethanol is 75%), then adding 5g of vinyltriethoxysilane, stirring and reacting at 65°C for 2.5h. After the reaction is completed, filtering, washing, and drying to obtain vinylated montmorillonite; S3. Evenly mix 55 g of vinylated montmorillonite prepared in step S2 and 3.5 g of bis(4-aminophenyl)phosphate to obtain a modified filler.

[0046] The preparation method of the masterbatch of the sheath layer material is as follows: weigh the raw materials according to the formula, add polypropylene, ethylene-octene copolymer, modified filler, maleic anhydride grafted polypropylene, antioxidant 1010, and zinc stearate into a high-speed mixer, mix for 10 minutes, and then add the mixture into a twin-screw extruder for extrusion and granulation at 210°C to obtain the sheath layer masterbatch.

[0047] Compared with Example 1, 2-mercaptobenzimidazole carboxylic acid is not introduced into the modified filler, and bis(4-aminophenyl)phosphate and montmorillonite are physically blended.

[0048] The sheath layer materials prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. The tensile strength and elongation at break were tested in accordance with GB / T 2951.11-2008 "General test methods for insulation and sheathing materials of electric and optical cables - Part 11: General test methods for thickness and dimensional measurements - Mechanical properties tests". The oxygen index was tested in accordance with GB / T 2406.2-2009 "Plastics - Determination of combustion behavior by oxygen index method - Part 2: Room temperature tests". The thermal aging test was carried out in accordance with GB / T 2951.12-2008 "General test methods for insulation and sheathing materials of electric and optical cables - Part 12: General test methods - Thermal aging test method". After the sheath was placed at 120°C for 480h, the tensile strength retention and elongation at break retention were tested. The UV aging conditions were: UV light intensity 300W / m 2 , aging temperature 50℃, aging time 168h; the test results are shown in Table 1 below.

[0049] Table 1 Test results of sheath material performance in each group

[0050] Table 2 Aging performance test results of each group

[0051] As can be seen from Tables 1 and 2 above, the wire harness sheath material prepared by the present invention has good mechanical properties, excellent flame retardancy, and outstanding resistance to ultraviolet aging and heat aging, providing an effective technical approach for preparing automotive wire harnesses with excellent comprehensive performance.

[0052] The above content is a further detailed description of the present invention in combination with specific implementation examples. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

[0053] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a flame-retardant and aging-resistant automotive wiring harness, characterized in that: The following steps are involved: Multiple tinned copper wires are twisted together to form a conductor core; an insulation layer is coated on the conductor core, and then an aluminum foil layer is coated on the outside of the insulation layer to obtain a single-strand wire harness; multiple single-strand wire harnesses are taken, separated by linings, and a sheath layer is coated on the outside of the multiple single-strand wire harnesses, and then a corrugated tube is placed on the outside of the sheath layer, and then an adhesive tape is wrapped around it, and fixed terminals are installed at both ends to obtain a flame-retardant and aging-resistant automotive wire harness product; The material of the sheath layer is composed of the following raw materials in parts by weight: 80-90 parts of polypropylene, 20-30 parts of ethylene-octene copolymer, 25-35 parts of modified filler, 10-15 parts of compatibilizer, 2-3 parts of antioxidant, and 1-2 parts of lubricant.

2. The preparation method according to claim 1, characterized in that The preparation method of the modified filler comprises the following steps: S1, montmorillonite was added to deionized water, followed by sodium lauryl sulfate, and after stirring and dispersing evenly, zinc sulfate solution was added, and stirred at room temperature for 3-4 hours, followed by dropwise addition of ammonium molybdate solution, and the pH was controlled at 8-9. After the addition was completed, the mixture was aged, filtered, washed, and dried to obtain a composite montmorillonite; S2, adding the composite montmorillonite to an ethanol aqueous solution, followed by adding vinyltriethoxysilane, and stirring to react to obtain vinylated montmorillonite; S3, adding vinylated montmorillonite to toluene, followed by adding 2-mercaptobenzimidazole carboxylic acid and azobisisobutyronitrile, and reacting at a constant temperature to obtain an organic montmorillonite; S4. Add the organized montmorillonite into DMF, then add EDC and NHS, stir at room temperature for 20-30 minutes, then add bis(4-aminophenyl)phosphate, and heat to react to obtain a modified filler.

3. The preparation method according to claim 2, characterized in that The mass ratio of the montmorillonite, deionized water, sodium lauryl sulfate, zinc sulfate solution, and ammonium molybdate solution in step S1 is 40-50:900-1000:0.3-0.5:60-80:50-70, the mass concentration of the zinc sulfate solution is 10-15%, and the mass concentration of the ammonium molybdate solution is 10-15%.

4. The preparation method according to claim 2, characterized in that The aging temperature in step S1 is 50-60° C. and the aging time is 6-8 hours.

5. The preparation method according to claim 2, characterized in that In step S2, the mass fraction of ethanol in the ethanol aqueous solution is 70-80%, the mass ratio of the composite montmorillonite and vinyltriethoxysilane is 50-60:4-6, the stirring reaction temperature is 60-70° C., and the time is 2-3 hours.

6. The preparation method according to claim 2, characterized in that In step S3, the mass ratio of vinyl montmorillonite, 2-mercaptobenzimidazole carboxylic acid, and azobisisobutyronitrile is 50-60:4-6:0.3-0.5, and the isothermal reaction temperature is 80-90° C. and the reaction time is 1-2 h.

7. The preparation method according to claim 2, characterized in that The mass ratio of the organized montmorillonite, bis(4-aminophenyl)phosphate, EDC, and NHS in step S4 is 50-60:2.5-4:4-6:2.5-3.

5.

8. The preparation method according to claim 2, characterized in that The heating reaction temperature in step S4 is 70-80° C. and the time is 2-3 h.

9. The preparation method according to claim 1, characterized in that The compatibilizer is maleic anhydride grafted polypropylene; the antioxidant is one or more of antioxidant 1010, antioxidant 1098, and antioxidant 168; and the lubricant includes one or more of zinc stearate, calcium stearate, and erucamide.

10. A flame-retardant and aging-resistant automotive wiring harness prepared by the method according to any one of claims 1 to 9.

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