High-flame-retardant electronic connecting wire and preparation method thereof

Abstract

The invention relates to a high-flame-retardant electronic connecting wire and a preparation method thereof, and belongs to the technical field of high polymer materials. The electronic connecting wire is composed of a wire and a flame-retardant protective layer on the surface of the wire, and the flame-retardant protective layer comprises the following components: 7.5-10 wt% of a modified phosphorus-silicon flame retardant, 14-18 wt% of a plasticizer, 1.7-2.2 wt% of a heat stabilizer, 0.12-0.16 wt% of an antioxidant, 0.9-1.3 wt% of a lubricant and the balance of PVC resin; the modified phosphorus-silicon flame retardant is prepared by the following steps: synthesizing a phosphoryl chloride intermediate 1 with a double-spiro structure from pentaerythritol and phosphorus oxychloride, carrying out amine ester exchange on amino-terminated polydimethylsiloxane and diethyl ketomalonate to prepare an amino-terminated intermediate 2, and reacting the intermediate 2 with active phosphoryl chloride of the intermediate 1 to prepare the modified phosphorus-silicon flame retardant. A chain-shaped macromolecular phosphamide compound is formed, and in-situ toughening, migration inhibition and carbon net flame retardance are simultaneously realized in a PVC matrix.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and in particular relates to a highly flame-retardant electronic connecting wire and a preparation method thereof. Background Art

[0002] As essential components in modern electronic equipment, power systems, and communication networks, the safety and reliability of electronic cables are crucial. Fire is a major safety hazard for electrical equipment, making the flame retardancy of cable insulation a key indicator of safety. Currently, polyvinyl chloride (PVC) remains the mainstream insulation material for electronic cables due to its excellent electrical insulation properties, processability, chemical resistance, and relatively low cost.

[0003] However, traditional PVC-based electronic cables have significant deficiencies in flame retardancy, especially in applications requiring higher flame retardancy ratings. This is primarily due to the following key factors: Plasticizer-induced flame retardancy impairment: To ensure the flexibility required for electronic cables during installation and use, large amounts of plasticizers must be added to the PVC base material. These plasticizers are typically flammable or combustible small organic molecules that dilute the inherent chlorine in the PVC resin, reducing charring efficiency and thus severely weakening the overall flame retardancy of the PVC insulation layer.

[0004] Hazards of molten droplets and smoke during combustion: When PVC is heated and burned, it easily produces high-temperature molten droplets. These droplets not only carry their own flames, igniting underlying combustibles and spreading the fire, but can also cause secondary damage to delicate electronic components. Furthermore, PVC combustion releases large amounts of dense, corrosive black smoke containing toxic gases such as hydrogen chloride, which not only seriously hinders escape and fire rescue efforts but also corrodes equipment, causing even greater secondary damage.

[0005] In order to improve the flame retardancy of PVC cables, the industry generally adopts the method of adding flame retardants. Commonly used flame retardants mainly include inorganic flame retardants and organic flame retardants. However, they all face severe challenges when applied to soft PVC electronic cables: Inorganic flame retardants offer high flame retardancy, significant smoke suppression, low toxicity, environmental friendliness, and low cost. However, the dosage required to achieve effective flame retardancy is typically very high. Such high levels of filler can severely damage the mechanical properties of PVC insulation, leading to severe embrittlement, a sharp decrease in flexibility, deterioration in tensile and impact resistance, and even compromising extrusion performance. This is a fatal flaw for flexible electronic cables that require frequent bending and plugging, easily leading to cracking and shedding, and loss of protection for the conductors.

[0006] Organic flame retardants have high flame retardancy and relatively little impact on the material's physical and mechanical properties, especially toughness. They can effectively maintain the flexibility and processing fluidity required of soft PVC. However, they have a high tendency to migrate and precipitate, exacerbating the droplet phenomenon during combustion and increasing the risk of ignition.

[0007] Therefore, developing a new flame retardant system and corresponding preparation method so that it can be effectively applied to the insulation layer of soft electronic connecting wires, while maintaining excellent flexibility and processing performance, to achieve high-level flame retardant protection with high efficiency, low smoke and no droplets, has become a key technical problem that needs to be urgently solved in this field. Summary of the Invention

[0008] In order to solve the technical problems mentioned in the background technology, the purpose of the present invention is to provide a highly flame-retardant electronic connecting wire and a preparation method thereof.

[0009] The purpose of the present invention can be achieved through the following technical solutions: A highly flame-retardant electronic connecting wire consists of a conductor and a flame-retardant protective layer on the surface. The flame-retardant protective layer comprises 7.5-10 wt% of a modified phosphorus silicon flame retardant, 14-18 wt% of a plasticizer, 1.7-2.2 wt% of a heat stabilizer, 0.12-0.16 wt% of an antioxidant, and 0.9-1.3 wt% of a lubricant, with the balance being PVC resin.

[0010] The modified phosphorus silicon flame retardant is prepared by the following method: Step A1: Pentaerythritol and anhydrous dioxane were mixed and dissolved by heating, and dry nitrogen was introduced to protect the mixture. The temperature was controlled at 70-80°C, and phosphorus oxychloride was slowly added and stirred for 4-4.5 hours. The pressure was then increased to 5.5-6.5 bar, and the temperature was further increased to 120-130°C for 1.5-2 hours. After the reaction was completed, the dioxane was removed by rotary evaporation to obtain Intermediate 1; In the reaction of step A1, the feed ratio of pentaerythritol, phosphorus oxychloride and anhydrous dioxane is 0.1 mol:0.2 mol:180-220 mL. Pentaerythritol and phosphorus oxychloride are esterified to form a phosphate compound containing a bispiro ring. The specific reaction route is as follows:

[0011] Step A2: Premix diethyl ketomalonate, amino-terminated polydimethylsiloxane, and anhydrous toluene, introduce dry nitrogen protection, heat to 80-90°C, add trimethylaluminum, and stir to react for 2-3 hours. After the reaction is complete, remove toluene by rotary evaporation to obtain intermediate 2; In the reaction of step A2, the feed ratio of diethyl ketomalonate, the amino content of amino-terminated polydimethylsiloxane, trimethylaluminum, and anhydrous toluene is 0.1 mol: 0.403-0.405 mol: 60-80 mg: 420-500 mL. The diethyl ketomalonate and amino-terminated polydimethylsiloxane undergo an amine transesterification reaction. The specific reaction route is as follows:

[0012] Preferably, the room temperature viscosity of the amino-terminated polydimethylsiloxane is not higher than 20 mm 2 / s, the low-viscosity raw materials have low molecular weight and high reactivity, the phosphorus silicon chain segments in the modified phosphorus silicon flame retardant molecular chain are more evenly distributed, and the carbon network formed at high temperature has better stability.

[0013] Step A3: Premix intermediate 2 and dimethylacetamide, pass dry nitrogen protection, add intermediate 1, mix, and heat to 40-55°C with stirring for 6-10 hours. Then, add triethylamine and reduce the pressure to 100 Pa. Continue to heat to 140-150°C and continue to react for 2-2.5 hours. After the reaction is completed, add deionized water for washing, separate the aqueous phase, and dry to obtain a modified phosphorus silicon flame retardant; In the reaction of step A3, the amino content of intermediate 1 and intermediate 2, and the feed ratio of triethylamine and dimethylacetamide are 0.1 mol:0.2 mol:25-30 mL:350-400 mL. Intermediate 1 and intermediate 2 undergo amidation reaction to form a polymer. The specific reaction route is as follows:

[0014] Preferably, the plasticizer is epoxidized soybean oil, which has good compatibility with both the PVC matrix and the modified phosphorus silicon flame retardant component, reduces the formation of incompatible interfaces, and is conducive to maintaining the overall mechanical properties of the composite system.

[0015] Preferably, the lubricant is a composite of low-density polyethylene wax and calcium stearate, which effectively improves the fluidity of the melt, facilitates the full mixing of the modified phosphorus silicon flame retardant and the PVC matrix, and has both internal and external lubrication effects, which is beneficial to improving the molding quality of the flame retardant protective layer.

[0016] A method for preparing a highly flame-retardant electronic connecting wire, specifically comprising: Step S1: uniformly mix the raw materials of each component, and then plasticize and mix the mixture using a twin-screw extruder, and then extrude and granulate the mixture to obtain a flame retardant masterbatch; Step S2: coating the flame retardant masterbatch on the surface of the wire using a single-screw extruder, forming a flame retardant protective layer after cooling, and obtaining a highly flame retardant electronic connecting wire.

[0017] Beneficial effects of the present invention: The application synthesizes a modified phosphorus-silicon flame retardant to prepare an insulating protective layer of an electronic connecting wire by blending with PVC. The modified phosphorus-silicon flame retardant is synthesized by pentaerythritol and phosphorus oxychloride intermediate 1 with double spiro ring structure, by amine-ester exchange of amino-terminated polydimethylsiloxane and ketone diethyl malonate to prepare intermediate 2 containing terminal amino group, and by reaction of intermediate 2 and active phosphorus oxychloride of intermediate 1 to form a chain-like macromolecular phosphoric amide compound, i.e. the modified phosphorus-silicon flame retardant. Compared with the existing flame retardant system, the application has the following advantages: first, the modified phosphorus-silicon flame retardant itself has a macromolecular chain structure, and has strong heat resistance and migration resistance; second, the multiple carbonyl groups on the modified phosphorus-silicon flame retardant molecule form a dipole-dipole interaction with the chlorine groups on the PVC macromolecule, and then the modified phosphorus-silicon flame retardant macromolecule and the PVC macromolecule are intertwined, on the one hand to strengthen the migration resistance, and on the other hand, the phosphorus double spiro ring structure introduced by intermediate 1 forms a large space structure, and under the dipole interaction, it is embedded between the PVC chains to weaken the intermolecular force, and plays a good self-toughening effect; third, the modified phosphorus-silicon flame retardant is an ordered phosphorus double spiro ring structure-silicon structure, in a fire state, the phosphorus double spiro ring structure is preferentially decomposed to promote the carbonization of the PVC chain in the intertwined section to form carbon particles, and these high-temperature-resistant carbon particles are connected by high-temperature-resistant silicon structures, and then form a large number of carbon particle-connected flame-retardant carbon nets in the space layer, which hinders the deepening of combustion, and at the same time, inhibits the release of smoke and the generation of softened PVC melt drops, and has excellent flame-retardant effect. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0019] Embodiment 1, preparation of high-flame-retardant electronic connecting wire, the specific implementation process is as follows: (1) Preparation of modified phosphorus-silicon flame retardant Step A1: pentaerythritol and anhydrous dioxane were mixed and dissolved by heating, dry nitrogen was introduced for protection, the temperature was controlled at 70°C, and phosphorus oxychloride was slowly added and stirred for 4.5h, then nitrogen was continuously introduced to increase the pressure to 5.5bar, and the temperature was continuously increased to 120°C for 2h, wherein the feeding ratio of pentaerythritol, phosphorus oxychloride and anhydrous dioxane was 0.1mol:0.2mol:180mL, after the reaction was completed, dioxane was removed by rotary evaporation to obtain intermediate 1.

[0020] Step A2: Premix diethyl ketomalonate, amino-terminated polydimethylsiloxane, and anhydrous toluene, introduce dry nitrogen protection, heat to 80°C, add trimethylaluminum, and stir to react for 3 hours. The amino-terminated polydimethylsiloxane is commercially available Cheersil 8110, with a room temperature viscosity of approximately 15 mm. 2 / s, the feed ratio of diethyl ketomalonate, the amino content of amino-terminated polydimethylsiloxane, trimethylaluminum and anhydrous toluene is 0.1 mol: 0.403 mol: 60 mg: 420 mL, and the toluene is removed by rotary evaporation after the reaction is completed to obtain intermediate 2.

[0021] Step A3: Premix intermediate 2 and dimethylacetamide, introduce dry nitrogen protection, add intermediate 1, mix and heat to 40°C with stirring for 10 hours, then add triethylamine and reduce the pressure to 100 Pa, continue to heat to 140°C and continue to react for 2.5 hours, wherein the amino content of intermediate 1 and intermediate 2, and the feed ratio of triethylamine and dimethylacetamide are 0.1 mol: 0.2 mol: 25 mL: 350 mL. After the reaction is completed, add deionized water for washing, separate the aqueous phase and dry it to obtain a modified phosphosilicate flame retardant.

[0022] (2) Preparation of electronic connecting wires Step S1: Take the raw materials according to weight percentage, 7.5wt% of the modified phosphorus silicon flame retardant is prepared in this embodiment; 18wt% of the plasticizer is a commercially available epoxy soybean oil plasticizer; 1.7wt% of the heat stabilizer is a commercially available GP-182 calcium zinc composite heat stabilizer; 0.16wt% of the antioxidant is a commercially available antioxidant 1010 and antioxidant 168 compounded in an equal weight ratio; 1.3wt% of the lubricant is a commercially available CERALENE® 2T low-density polyethylene wax and industrial-grade calcium stearate compounded in a weight ratio of 2:1; the remainder is PVC resin, using SG-3 type resin raw material; add the raw materials of each component into a high-speed mixer and mix them evenly, and the mixture is plasticized and mixed at 180°C using a twin-screw extruder, and then extruded and granulated to obtain a flame retardant masterbatch.

[0023] Step S2: Extruding the flame retardant masterbatch at 180° C. using a single-screw extruder to coat the surface of the wire, and forming a flame retardant protective layer after cooling to obtain a highly flame retardant electronic connecting wire.

[0024] Example 2: Preparation of highly flame-retardant electronic connecting wires. The specific implementation process is as follows: (1) Preparation of modified phosphorus silicon flame retardant Step A1: Pentaerythritol and anhydrous dioxane were mixed and heated, and dry nitrogen was introduced to protect the mixture. The temperature was controlled at 80°C, and phosphorus oxychloride was slowly added and stirred for 4 hours. Nitrogen was then continued to be introduced to increase the pressure to 6 bar. The temperature was continued to be raised to 125°C and the reaction was carried out for 1.7 hours. The feed ratio of pentaerythritol, phosphorus oxychloride, and anhydrous dioxane was 0.1 mol:0.2 mol:200 mL. After the reaction was completed, the dioxane was removed by rotary evaporation to obtain Intermediate 1.

[0025] Step A2: Premix diethyl ketomalonate, amino-terminated polydimethylsiloxane, and anhydrous toluene, introduce dry nitrogen protection, heat to 85°C, add trimethylaluminum, and stir to react for 2.5 hours. The amino-terminated polydimethylsiloxane is commercially available Cheersil 8110, with a room temperature viscosity of approximately 15 mm. 2 / s, the feed ratio of diethyl ketomalonate, the amino content of amino-terminated polydimethylsiloxane, trimethylaluminum and anhydrous toluene is 0.1 mol: 0.404 mol: 70 mg: 450 mL, and the toluene is removed by rotary evaporation after the reaction is completed to obtain intermediate 2.

[0026] Step A3: Premix intermediate 2 and dimethylacetamide, introduce dry nitrogen protection, add intermediate 1, mix and heat to 50°C with stirring for 7 hours, then add triethylamine and reduce the pressure to 100 Pa, continue to heat to 150°C and continue to react for 2.2 hours, wherein the amino content of intermediate 1 and intermediate 2, and the feed ratio of triethylamine and dimethylacetamide are 0.1 mol: 0.2 mol: 28 mL: 370 mL. After the reaction is completed, add deionized water for washing, separate the aqueous phase and dry it to obtain a modified phosphosilicate flame retardant.

[0027] (2) Preparation of electronic connecting wires Step S1: Take the raw materials according to weight percentage, 9.2wt% of the modified phosphorus silicon flame retardant is prepared in this embodiment; 15wt% of the plasticizer is a commercially available epoxy soybean oil plasticizer; 2wt% of the heat stabilizer is a commercially available GP-182 calcium zinc composite heat stabilizer; 0.13wt% of the antioxidant is a commercially available antioxidant 1010 and antioxidant 168 compounded in an equal weight ratio; 1.1wt% of the lubricant is a commercially available CERALENE® 2T low-density polyethylene wax and industrial-grade calcium stearate compounded in a weight ratio of 2:1; the remainder is PVC resin, using SG-3 type resin raw material; add the raw materials of each component into a high-speed mixer and mix them evenly, and the mixture is plasticized and mixed at 170°C using a twin-screw extruder, and then extruded and granulated to obtain a flame retardant masterbatch.

[0028] Step S2: Extruding the flame retardant masterbatch at 180° C. using a single-screw extruder to coat the surface of the wire, and forming a flame retardant protective layer after cooling to obtain a highly flame retardant electronic connecting wire.

[0029] Example 3, preparing a highly flame-retardant electronic connecting wire, the specific implementation process is as follows: (1) Preparation of modified phosphorus silicon flame retardant Step A1: Pentaerythritol and anhydrous dioxane were mixed and heated, and dry nitrogen was introduced to protect the mixture. The temperature was controlled at 80°C, and phosphorus oxychloride was slowly added and stirred for 4 hours. Nitrogen was then continued to be introduced to increase the pressure to 6.5 bar. The temperature was continued to be raised to 130°C and the reaction was carried out for 1.5 hours. The feed ratio of pentaerythritol, phosphorus oxychloride and anhydrous dioxane was 0.1 mol:0.2 mol:220 mL. After the reaction was completed, the dioxane was removed by rotary evaporation to obtain intermediate 1.

[0030] Step A2: Premix diethyl ketomalonate, amino-terminated polydimethylsiloxane, and anhydrous toluene, introduce dry nitrogen protection, heat to 90°C, add trimethylaluminum, and stir to react for 2 hours. The amino-terminated polydimethylsiloxane is commercially available Cheersil 8110, with a room temperature viscosity of approximately 15 mm. 2 / s, the feed ratio of diethyl ketomalonate, the amino content of amino-terminated polydimethylsiloxane, trimethylaluminum and anhydrous toluene is 0.1 mol: 0.405 mol: 80 mg: 500 mL, and the toluene is removed by rotary evaporation after the reaction is completed to obtain intermediate 2.

[0031] Step A3: Premix intermediate 2 and dimethylacetamide, introduce dry nitrogen protection, add intermediate 1, mix and heat to 55°C with stirring for 6 hours, then add triethylamine and reduce the pressure to 100 Pa, continue to heat to 150°C and continue to react for 2 hours, wherein the amino content of intermediate 1 and intermediate 2, and the feed ratio of triethylamine and dimethylacetamide are 0.1 mol: 0.2 mol: 30 mL: 400 mL. After the reaction is completed, add deionized water for washing, separate the aqueous phase and dry it to obtain a modified phosphosilicate flame retardant.

[0032] (2) Preparation of electronic connecting wires Step S1: Take the raw materials according to weight percentage, 10wt% of the modified phosphorus silicon flame retardant is prepared in this embodiment; 14wt% of the plasticizer is a commercially available epoxy soybean oil plasticizer; 2.2wt% of the heat stabilizer is a commercially available GP-182 calcium zinc composite heat stabilizer; 0.12wt% of the antioxidant is a commercially available antioxidant 1010 and antioxidant 168 compounded in an equal weight ratio; 0.9wt% of the lubricant is a commercially available CERALENE® 2T low-density polyethylene wax and industrial-grade calcium stearate compounded in a weight ratio of 2:1; the remainder is PVC resin, using SG-3 type resin raw material; add the raw materials of each component into a high-speed mixer and mix them evenly, and the mixture is plasticized and mixed at 170°C using a twin-screw extruder, and then extruded and granulated to obtain a flame retardant masterbatch.

[0033] Step S2: Extruding the flame retardant masterbatch at 180° C. using a single-screw extruder to coat the surface of the wire, and forming a flame retardant protective layer after cooling to obtain a highly flame retardant electronic connecting wire.

[0034] Example 4: Preparation of highly flame-retardant electronic connecting wires. The specific implementation process is as follows: (1) Preparation of modified phosphorus silicon flame retardant Step A1: Pentaerythritol and anhydrous dioxane were mixed and heated, and dry nitrogen was introduced to protect the mixture. The temperature was controlled at 75°C, and phosphorus oxychloride was slowly added and stirred to react for 4.5 hours. Nitrogen was then continued to be introduced to increase the pressure to 6 bar. The temperature was continued to be raised to 120°C and reacted for 1.8 hours. The feed ratio of pentaerythritol, phosphorus oxychloride, and anhydrous dioxane was 0.1 mol:0.2 mol:210 mL. After the reaction was completed, the dioxane was removed by rotary evaporation to obtain Intermediate 1.

[0035] Step A2: Premix diethyl ketomalonate, amino-terminated polydimethylsiloxane, and anhydrous toluene, introduce dry nitrogen protection, heat to 80°C, add trimethylaluminum, and stir to react for 2.5 hours. The amino-terminated polydimethylsiloxane is commercially available Cheersil 8110, with a room temperature viscosity of approximately 15 mm. 2 / s, the feed ratio of diethyl ketomalonate, the amino content of amino-terminated polydimethylsiloxane, trimethylaluminum and anhydrous toluene is 0.1 mol: 0.405 mol: 75 mg: 460 mL, and the toluene is removed by rotary evaporation after the reaction is completed to obtain intermediate 2.

[0036] Step A3: Premix intermediate 2 and dimethylacetamide, introduce dry nitrogen protection, add intermediate 1, mix and heat to 45°C with stirring for 8.5h, then add triethylamine and reduce the pressure to 100Pa, continue to heat to 140°C and continue to react for 2.5h, wherein the amino content of intermediate 1 and intermediate 2, and the feed ratio of triethylamine and dimethylacetamide are 0.1mol:0.2mol:30mL:380mL. After the reaction is completed, add deionized water for washing, separate the aqueous phase and dry it to obtain a modified phosphosilicate flame retardant.

[0037] (2) Preparation of electronic connecting wires Step S1: Take the raw materials according to weight percentage, 8.8wt% of the modified phosphorus silicon flame retardant is prepared in this embodiment; 16wt% of the plasticizer is a commercially available epoxy soybean oil plasticizer; 1.9wt% of the heat stabilizer is a commercially available GP-182 calcium zinc composite heat stabilizer; 0.15wt% of the antioxidant is a commercially available antioxidant 1010 and antioxidant 168 compounded in an equal weight ratio; 1.2wt% of the lubricant is a commercially available CERALENE® 2T low-density polyethylene wax and industrial-grade calcium stearate compounded in a weight ratio of 2:1; the remainder is PVC resin, using SG-3 type resin raw material; add the raw materials of each component into a high-speed mixer and mix them evenly, and the mixture is plasticized and mixed at 180°C using a twin-screw extruder, and then extruded and granulated to obtain a flame retardant masterbatch.

[0038] Step S2: Extruding the flame retardant masterbatch at 180° C. using a single-screw extruder to coat the surface of the wire, and forming a flame retardant protective layer after cooling to obtain a highly flame retardant electronic connecting wire.

[0039] Comparative Example 1: This comparative example is a control example of Example 4. FRX-100 organosilicon flame retardant and OP 935 phosphorus flame retardant are compounded in a weight ratio of 3:1 to replace the modified phosphorus silicon flame retardant in equal amounts. The rest of the implementation process is exactly the same.

[0040] Comparative Example 2: This comparative example is a control example of Example 4, except that an equal amount of FR-AHP02 phosphorus silicon flame retardant is used to replace the modified phosphorus silicon flame retardant, and the rest of the implementation process is exactly the same.

[0041] Samples of the flame retardant masterbatch prepared above were injection molded into specimens with a thickness of 2 mm. The tensile test was performed according to ASTM D638-2022, the impact test was performed according to ASTM D256-2024, the flame retardancy test was performed according to UL94, the oxygen index test was performed according to ASTM D2863-2023, and the smoke density test was performed according to ASTM E662-2017. The specific test data are shown in Table 1: Table 1

[0042] It can be seen from the test results in Table 1 that the flame retardant protective layer material of the embodiment maintains moderate tensile strength, meets the protection requirements of electronic connecting wires, and has an impact strength significantly higher than that of the comparative example, indicating that the introduction of the modified phosphorus silicon flame retardant can significantly improve the mechanical toughness of the PVC matrix compared to the existing flame retardant system. In terms of flame retardant properties, the flame retardant grade of the embodiment reaches V-0, the oxygen index reaches about 40%, and it has high flame retardant properties, and the smoke density is less than 100, which has low smoke characteristics.

[0043] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0044] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A highly flame-retardant electronic connecting wire, consisting of a conductor and a flame-retardant protective layer on the surface, characterized in that: The flame retardant protective layer comprises: 7.5-10 wt% of a modified phosphorus silicon flame retardant, 14-18 wt% of a plasticizer, 1.7-2.2 wt% of a heat stabilizer, 0.12-0.16 wt% of an antioxidant, and 0.9-1.3 wt% of a lubricant, with the balance being PVC resin. The modified phosphorus silicon flame retardant is prepared by the following method: Step A1: Pentaerythritol and anhydrous dioxane were mixed and dissolved by heating, and dry nitrogen was introduced to protect the mixture. The temperature was controlled at 70-80°C, and phosphorus oxychloride was slowly added and stirred for 4-4.5 hours. The pressure was then increased to 5.5-6.5 bar, and the temperature was further increased to 120-130°C and the mixture was reacted for 1.5-2 hours to prepare Intermediate 1; Step A2: premix diethyl ketomalonate, amino-terminated polydimethylsiloxane, and anhydrous toluene, introduce dry nitrogen protection, heat to 80-90°C, add trimethylaluminum, and stir to react for 2-3 hours to prepare intermediate 2; Step A3: Premix intermediate 2 and dimethylacetamide, pass dry nitrogen protection, add intermediate 1, mix and heat to 40-55°C, stir and react for 6-10 hours, then add triethylamine and reduce the pressure to 100 Pa, continue to heat to 140-150°C and continue to react for 2-2.5 hours to prepare a modified phosphosilicate flame retardant.

2. A highly flame-retardant electronic connecting wire according to claim 1, characterized in that: The feeding ratio of pentaerythritol, phosphorus oxychloride and anhydrous dioxane is 0.1 mol: 0.2 mol: 180-220 mL.

3. A highly flame-retardant electronic connecting wire according to claim 2, characterized in that: The feed ratio of diethyl ketomalonate, the amino content of amino-terminated polydimethylsiloxane, trimethylaluminum and anhydrous toluene is 0.1 mol: 0.403-0.405 mol: 60-80 mg: 420-500 mL.

4. A highly flame-retardant electronic connecting wire according to claim 3, characterized in that: The room temperature viscosity of amino-terminated polydimethylsiloxane is not higher than 20mm 2 / s.

5. The highly flame-retardant electronic connecting wire according to claim 4, characterized in that: The amino content of intermediate 1 and intermediate 2, and the feeding ratio of triethylamine and dimethylacetamide are 0.1 mol: 0.2 mol: 25-30 mL: 350-400 mL.

6. The highly flame-retardant electronic connecting wire according to claim 1, characterized in that: The plasticizer is epoxidized soybean oil.

7. The highly flame-retardant electronic connecting wire according to claim 1, characterized in that: The lubricant is a composite of low-density polyethylene wax and calcium stearate.

8. A method for preparing a highly flame-retardant electronic connecting wire according to any one of claims 1 to 7, characterized in that: Specifically: Step S1: uniformly mix the raw materials of each component, and then plasticize and mix the mixture using a twin-screw extruder, and then extrude and granulate the mixture to obtain a flame retardant masterbatch; Step S2: coating the flame retardant masterbatch on the surface of the wire using a single-screw extruder, forming a flame retardant protective layer after cooling, and obtaining a highly flame retardant electronic connecting wire.

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