High-molecular sheath material for multifunctional speed sensor cable of high-speed motor train unit

Abstract

The invention relates to the technical field of cable polymer sheaths, in particular to a polymer sheath material for a multifunctional speed sensor cable of a high-speed motor train unit, which is prepared from the following raw materials in parts by weight: basic resin; reinforcing the modified material; a functional additive; an environmental stabilizer; a processing aid; the environment stabilizer is composed of a composite antioxidant, an ultraviolet light absorber and an ozone stabilizer. Through basic resin composite modification and functional component synergistic optimization, in combination with nano silicon nitride and aramid chopped fiber reinforcement, and in combination with functional additives such as the halogen-free flame retardant and the carbon nanotubes and a special environment stabilizer, the comprehensive performance of the material is improved, extremely cold and high-temperature part radiation can be resisted, and the service life of the material is prolonged. The volume change rate is less than or equal to 5% after the cable is soaked in special lubricating oil for the motor train unit for 72 hours, the flame retardant property is higher, meanwhile, the cable is halogen-free and environment-friendly, the service life of the sensor cable is remarkably prolonged, and stable transmission of speed signals is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of polymer sheath technology for cables, specifically a polymer sheath material for multi-functional speed sensor cables for high-speed trains. Background Technology

[0002] The multi-functional speed sensor cable of high-speed train is a core transmission component of the train's operation control system. It needs to work under complex conditions such as high-frequency vibration, alternating high and low temperatures, oil corrosion, ultraviolet radiation and ozone environment for a long time. Its sheath material must meet multiple stringent requirements such as high and low temperature resistance, vibration fatigue resistance, wear resistance, oil resistance, flame retardancy and environmental protection, and signal transmission stability.

[0003] Traditional polymer sheathing materials for cables, such as polyvinyl chloride (PVC), polyethylene (PE), cross-linked polyethylene (XLPE), and ethylene propylene rubber (EPR), have significant drawbacks when applied in this scenario: PVC has a narrow temperature range, is prone to brittleness in extremely cold environments and softens easily at high temperatures, and releases toxic gases when burning, and has poor oil resistance; polyethylene has insufficient abrasion resistance, is prone to aging and brittleness after long-term exposure, and is prone to microcracks under high-frequency vibration; XLPE has poor fatigue resistance, insufficient oil resistance, and lacks flame retardancy; EPR has obvious shortcomings in abrasion resistance and oil resistance, and its flame retardancy is difficult to meet standards. These defects can lead to sheath damage, signal transmission interruption, and even safety hazards, seriously affecting the operational safety and reliability of high-speed trains.

[0004] Based on this, the present invention provides a polymer sheath material for multi-functional speed sensor cables of high-speed trains to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a polymer sheath material for multi-functional speed sensor cables for high-speed trains, thereby solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention proposes a polymer sheath material for a multi-functional speed sensor cable in high-speed trains, which is composed of the following raw materials in parts by weight: base resin: 75-88 parts; reinforcing and modifying materials: 6-12 parts; functional additives: 3.2-6.8 parts; environmental stabilizer: 2.5-4.5 parts; processing aids: 1.3-2.7 parts; The environmental stabilizer is composed of a composite antioxidant, an ultraviolet absorber, and an ozone stabilizer, wherein the composite antioxidant is 0.8-1.5 parts, the ultraviolet absorber is 0.9-1.6 parts, and the ozone stabilizer is 0.8-1.4 parts. The composite antioxidant is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 1:1; the ultraviolet absorber is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole; and the ozone stabilizer is N-isopropyl-N'-phenyl-p-phenylenediamine.

[0007] Preferably, the base resin is composed of a polyether-type polyurethane elastomer and hydrogenated nitrile rubber, wherein the polyether-type polyurethane elastomer comprises 60-72 parts and the hydrogenated nitrile rubber comprises 15-16 parts.

[0008] Preferably, the reinforcing and modified material is composed of nano-silicon nitride and aramid chopped fibers, wherein the nano-silicon nitride comprises 2-4 parts and the aramid chopped fibers comprises 4-8 parts.

[0009] Preferably, the functional additive is composed of a halogen-free flame retardant, methylphenylsiloxane, and carbon nanotubes, wherein the halogen-free flame retardant comprises 1.5-3 parts, the methylphenylsiloxane comprises 1-2 parts, and the carbon nanotubes comprises 0.7-1.8 parts.

[0010] Preferably, the processing aid is composed of calcium stearate, polyethylene wax and maleic anhydride graft compatibilizer, wherein the calcium stearate is 0.4-0.9 parts, the polyethylene wax is 0.3-0.8 parts, and the maleic anhydride graft compatibilizer is 0.6-1.0 parts.

[0011] Preferably, the halogen-free flame retardant is composed of magnesium hydroxide and ammonium polyphosphate in a mass ratio of 3:2; the carbon nanotubes are multi-walled carbon nanotubes with a diameter of 10-20 nm and a length of 5-10 μm.

[0012] Based on the above-mentioned polymer sheath material, this invention also proposes a preparation process for a polymer sheath material for a multi-functional speed sensor cable of a high-speed train, comprising the following steps: S1. Dry 60-72 parts of polyether-type polyurethane elastomer and 15-16 parts of hydrogenated nitrile rubber in a constant temperature drying oven at 60℃ for 4 hours to remove moisture; treat 2-4 parts of nano-silicon nitride with silane coupling agent KH-550 for surface modification; dry 4-8 parts of aramid chopped fiber at 120℃ for 2 hours, controlling the moisture content to below 0.3%; store all liquid additives at a constant temperature of 25±3℃ to avoid separation; S2. Add the dried base resin, modified reinforcing material, halogen-free flame retardant and carbon nanotubes from the functional additives, and environmental stabilizer to a high-speed mixer and mix in three stages: Coarse mixing: Stir at 800 rpm for 5 minutes to eliminate raw material accumulation; Fine mixing: Stir at 1200 r / min for 10 min, then add 1-2 parts of methylphenylsiloxane; Homogenization: Stir at 1500 r / min for 3 min, achieving a mixing uniformity of ≥99%; S3. Add 0.4-0.9 parts of processing aid calcium stearate, 0.3-0.8 parts of polyethylene wax, 0.6-1.0 parts of maleic anhydride graft compatibilizer and the mixture obtained in step S2 into a twin-screw extruder, set the temperature of each section of the extruder, and carry out melt blending extrusion at a screw speed of 350 r / min. The extrudate is then water-cooled and pelletized to obtain primary particles. S4. The primary particles are fed into a single-screw extruder for secondary plasticization. The barrel temperature is set to 160-170℃, the die head temperature to 165℃, and the screw speed to 280r / min. The material is extruded through the die to form a sheath blank. Nitrogen gas is used to protect the die outlet to prevent oxidation. S5. Place the sheath blank in a constant temperature and humidity curing chamber for post-treatment at 80℃ and 50% humidity for 8 hours to eliminate internal stress; then perform low-temperature aging treatment at -40℃ for 2 hours, and then allow it to naturally warm to room temperature. S6. Perform performance testing on the sheath material after step S5, and package it after it passes the test.

[0013] Preferably, the performance testing items in step S6 include high and low temperature resistance, wear resistance, oil resistance, flame retardancy, and vibration fatigue resistance.

[0014] Preferably, the temperatures of each section of the extruder in step S3 are 140°C for the feeding section, 160°C for the compression section, 175°C for the melting section, and 165°C for the die head section.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves a leap in the comprehensive performance of materials through the composite modification of basic resin and the synergistic optimization of functional components, combined with the reinforcement of nano-silicon nitride and aramid short-cut fibers, and the addition of halogen-free flame retardants, carbon nanotubes and other functional additives and special environmental stabilizers. It can withstand radiation from components in extreme cold and high temperature conditions, has vibration fatigue resistance that meets the requirements of high-frequency vibration without cracking, excellent oil resistance (the volume change rate after immersion in special lubricating oil for high-speed trains is ≤5% after 72 hours), higher flame retardant performance, and is halogen-free and environmentally friendly, releasing no toxic gases when burned. It also significantly extends the service life of sensor cables and ensures stable transmission of speed signals. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] I. Materials: Unless otherwise specified, the polymer sheath material formulation for the high-speed train multi-functional speed sensor cable of this invention is commercially available. This invention proposes a polymer sheath material for a multi-functional speed sensor cable for high-speed trains, which is composed of the following raw materials in parts by weight: base resin: 75-88 parts; reinforcing and modifying materials: 6-12 parts; functional additives: 3.2-6.8 parts; environmental stabilizers: 2.5-4.5 parts; processing aids: 1.3-2.7 parts.

[0018] It should be noted that the base resin is composed of polyether-type polyurethane elastomer and hydrogenated nitrile rubber, wherein the polyether-type polyurethane elastomer comprises 60-72 parts and the hydrogenated nitrile rubber comprises 15-16 parts.

[0019] It should be noted that the reinforcing and modified material is composed of nano-silicon nitride and aramid short-cut fibers, wherein the nano-silicon nitride comprises 2-4 parts and the aramid short-cut fibers comprise 4-8 parts.

[0020] It should be noted that the functional additive is composed of a halogen-free flame retardant, methylphenylsiloxane, and carbon nanotubes, wherein the halogen-free flame retardant comprises 1.5-3 parts, the methylphenylsiloxane comprises 1-2 parts, and the carbon nanotubes comprises 0.7-1.8 parts.

[0021] It should be noted that the environmental stabilizer is composed of a composite antioxidant, an ultraviolet absorber, and an ozone stabilizer, wherein the composite antioxidant is 0.8-1.5 parts, the ultraviolet absorber is 0.9-1.6 parts, and the ozone stabilizer is 0.8-1.4 parts.

[0022] It should be noted that the processing aid is composed of calcium stearate, polyethylene wax and maleic anhydride graft compatibilizer, wherein the amount of calcium stearate is 0.4-0.9 parts, the amount of polyethylene wax is 0.3-0.8 parts, and the amount of maleic anhydride graft compatibilizer is 0.6-1.0 parts.

[0023] It should be noted that the composite antioxidant is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 1:1; the ultraviolet absorber is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole; and the ozone stabilizer is N-isopropyl-N'-phenyl-p-phenylenediamine.

[0024] It should be noted that the halogen-free flame retardant is composed of magnesium hydroxide and ammonium polyphosphate in a mass ratio of 3:2; the carbon nanotubes are multi-walled carbon nanotubes with a diameter of 10-20 nm and a length of 5-10 μm.

[0025] II. Process: Based on the above formula, the present invention also proposes a preparation process for a polymer sheath material for a multi-functional speed sensor cable of a high-speed train, specifically including the following steps: S1. Dry 60-72 parts of polyether-type polyurethane elastomer and 15-16 parts of hydrogenated nitrile rubber in a constant temperature drying oven at 60℃ for 4 hours to remove moisture; treat 2-4 parts of nano-silicon nitride with silane coupling agent KH-550 for surface modification; dry 4-8 parts of aramid chopped fiber at 120℃ for 2 hours, controlling the moisture content to below 0.3%; store all liquid additives at a constant temperature of 25±3℃ to avoid separation; S2. Add the dried base resin, modified reinforcing material, halogen-free flame retardant and carbon nanotubes from the functional additives, and environmental stabilizer to a high-speed mixer and mix in three stages: Coarse mixing: Stir at 800 rpm for 5 minutes to eliminate raw material accumulation; Fine mixing: Stir at 1200 r / min for 10 min, then add 1-2 parts of methylphenylsiloxane; Homogenization: Stir at 1500 r / min for 3 min, achieving a mixing uniformity of ≥99%; S3. Add 0.4-0.9 parts of processing aid calcium stearate, 0.3-0.8 parts of polyethylene wax, 0.6-1.0 parts of maleic anhydride graft compatibilizer and the mixture obtained in step S2 into a twin-screw extruder. Set the temperatures of each section of the extruder as follows: feeding section 140℃, compression section 160℃, melting section 175℃, and die head section 165℃. Perform melt blending extrusion at a screw speed of 350 r / min. The extrudate is then water-cooled and pelletized to obtain primary particles. S4. The primary particles are fed into a single-screw extruder for secondary plasticization. The barrel temperature is set to 160-170℃, the die head temperature to 165℃, and the screw speed to 280r / min. The material is extruded through the die to form a sheath blank. Nitrogen gas is used to protect the die outlet to prevent oxidation. S5. Place the sheath blank in a constant temperature and humidity curing chamber for post-treatment at 80℃ and 50% humidity for 8 hours to eliminate internal stress; then perform low-temperature aging treatment at -40℃ for 2 hours, and then allow it to naturally warm to room temperature. S6. Perform performance testing on the sheath material after step S5, and package it after it passes the test.

[0026] It should be noted that the performance testing items in step S6 include high and low temperature resistance, wear resistance, oil resistance, flame retardancy, and vibration fatigue resistance.

[0027] Example 1: In this example, a polymer sheath material for a multi-functional speed sensor cable of a high-speed train was prepared according to the following process. The formulation components are as follows: Base resin: 66 parts of polyether-type polyurethane elastomer, 15.5 parts of hydrogenated nitrile rubber; Reinforcing and modifying materials: 3 parts of nano-silicon nitride, 6 parts of aramid chopped fiber; Functional additives: 2.2 parts of halogen-free flame retardant, 1.5 parts of methylphenylsiloxane, 1.2 parts of carbon nanotubes; Environmental stabilizers: 1.1 parts of composite antioxidant, 1.2 parts of ultraviolet absorber, 1.1 parts of ozone stabilizer; Processing aids: 0.6 parts of calcium stearate, 0.5 parts of polyethylene wax, 0.8 parts of maleic anhydride graft compatibilizer. Includes the following steps: Step S1: Raw material pretreatment and metering: Base resin: 66 parts of polyether-type polyurethane elastomer and 15.5 parts of hydrogenated nitrile rubber were dried in a 60℃ constant temperature drying oven for 4 hours to remove moisture; Reinforcing and modifying materials: 3 parts of nano-silicon nitride were soaked in silane coupling agent KH-550 for 15 minutes for surface modification, and 6 parts of aramid short-cut fiber were dried in a 120℃ oven for 2 hours with the moisture content controlled at 0.3%; Liquid additives: 1.5 parts of methylphenylsiloxane were stored at a constant temperature of 25℃; Step S2: Mixing and preparation: Coarse mixing: Add the dried base resin, 3 parts of modified nano-silicon nitride, 6 parts of aramid short-cut fiber, 2.2 parts of halogen-free flame retardant and 1.2 parts of carbon nanotubes from the functional additives, and environmental stabilizers (1.1 parts of composite antioxidant, 1.2 parts of ultraviolet absorber, and 1.1 parts of ozone stabilizer) into a high-speed mixer, rotate at 800 r / min, and stir for 5 min to eliminate raw material accumulation; Fine mixing: Keep the high-speed mixer running, increase the speed to 1200 r / min, stir for 10 min, and add 1.5 parts of methylphenylsiloxane; Homogenization: Increase the rotation speed to 1500 r / min and stir for 3 min to achieve a mixing uniformity of 99.2%; Step S3: Melt blending extrusion: 0.6 parts of processing aid calcium stearate, 0.5 parts of polyethylene wax, 0.8 parts of maleic anhydride graft compatibilizer and the mixture obtained in step 2 are fed into a twin-screw extruder. The temperatures of each section of the extruder are set as follows: feeding section 140℃, compression section 160℃, melting section 175℃, and die head section 165℃. The screw speed is 350 r / min. Melt blending extrusion is carried out. The extrudate is water-cooled and pelletized to obtain primary particles. Step S4: Secondary plasticizing and molding: The primary particles are fed into a single-screw extruder, the barrel temperature is set to 165℃, the die head temperature is set to 165℃, and the screw speed is set to 280r / min. The extrusion is formed into a sheath blank through the die, and nitrogen gas is introduced into the die outlet for protection to prevent oxidation. Step S5: Post-treatment: Place the sheath blank into a constant temperature and humidity curing chamber at 80℃ and 50% for 8 hours; then transfer it to a low temperature chamber at -40℃ for 2 hours, and then allow it to naturally warm to room temperature. Step S6: Performance Testing and Packaging: The sheath material is tested for high and low temperature resistance, wear resistance, oil resistance, flame retardancy, and vibration fatigue resistance. Packaging is carried out after all indicators pass the test.

[0028] Example 2: In this example, 60 parts of polyether-type polyurethane elastomer, 15 parts of hydrogenated nitrile rubber, 2 parts of nano-silicon nitride, 4 parts of aramid chopped fiber, 1.5 parts of halogen-free flame retardant, 1 part of methylphenylsiloxane, 0.7 parts of carbon nanotubes, 0.8 parts of composite antioxidant, 0.9 parts of ultraviolet absorber, 0.8 parts of ozone stabilizer, 0.4 parts of calcium stearate, 0.3 parts of polyethylene wax, and 0.6 parts of maleic anhydride graft compatibilizer were used. Other process parameters were the same as in Example 1.

[0029] Example 3: In this example, 72 parts of polyether-type polyurethane elastomer, 16 parts of hydrogenated nitrile rubber, 4 parts of nano-silicon nitride, 8 parts of aramid chopped fiber, 3 parts of halogen-free flame retardant, 2 parts of methylphenylsiloxane, 1.8 parts of carbon nanotubes, 1.5 parts of composite antioxidant, 1.6 parts of ultraviolet absorber, 1.4 parts of ozone stabilizer, 0.9 parts of calcium stearate, 0.8 parts of polyethylene wax, and 1.0 part of maleic anhydride graft compatibilizer were used. Other process parameters were the same as in Example 1.

[0030] The parameters of the sheath material prepared in the examples are shown in Table 1: Table 1: Parameters of the sheath material prepared in the examples

[0031] Comparative Example 1: In this comparative example, 1 part of nano-silicon nitride was used, and other process parameters were the same as in Example 1.

[0032] Comparative Example 2: In this comparative example, 4 parts of halogen-free flame retardant were used, and other process parameters were the same as in Example 1.

[0033] Comparative Example 3: In this comparative example, 0.5 parts of composite antioxidant were used, and other process parameters were the same as in Example 1.

[0034] The parameters of the sheath material prepared in the comparative example are shown in Table 2: Table 2: Parameters of Sheath Materials Prepared in Comparative Examples

[0035] III. Performance Testing: The following performance tests were performed on the sheath materials prepared in the examples and comparative examples: a. High and low temperature resistance: After being placed in environments of -55℃ and 125℃ for 24 hours respectively, observe whether the appearance becomes brittle, softened or deformed; b. Abrasion resistance: According to GB / T2951.14 standard, with a wear resistance of 1.5×10⁻⁶. 6 A second friction test was conducted to observe for any damage. c. Oil resistance: After immersion in special lubricating oil for high-speed trains for 72 hours, the volume change rate was tested; d. Flame retardant performance: The flame retardant rating is tested according to UL94 standard; e. Vibration fatigue resistance: Under conditions of frequency 50-2000Hz and amplitude 0.5mm, after 10... 6 Observe whether cracks are generated after each vibration.

[0036] Performance data for the examples and comparative examples are shown in Table 3: Table 3: Performance Data of Examples and Comparative Examples

[0037] IV. Analysis Conclusion: As shown in Tables 2 and 3, in Comparative Example 1, the insufficient amount of nano-silicon nitride led to a decrease in the material's wear resistance, a deterioration in its oil resistance, and slight cracks in its vibration fatigue resistance. In Comparative Example 2, the excessive amount of halogen-free flame retardant did not affect the flame retardant rating, but the material's flexibility decreased slightly, and the oil resistance index fluctuated slightly. In Comparative Example 3, the insufficient amount of composite antioxidant significantly reduced the anti-aging performance, and obvious cracks appeared in the vibration fatigue resistance. This verifies the scientific validity and rationality of the formulation component range of the present invention.

[0038] According to Tables 1 and 3, the formulation components of Example 1 of this invention are well-balanced. The 66 parts of polyether-type polyurethane elastomer and 15.5 parts of hydrogenated nitrile rubber work synergistically to ensure the basic flexibility and oil resistance of the material. The 3 parts of nano-silicon nitride and 6 parts of aramid chopped fiber are optimized and reinforced to achieve the best wear resistance and vibration fatigue resistance. The 2.2 parts of halogen-free flame retardant and 1.2 parts of carbon nanotubes work synergistically to retard flame, taking into account both environmental protection and flame retardant efficiency. The environmental stabilizer components are appropriately proportioned, with excellent anti-aging properties and optimal overall performance, fully meeting the stringent requirements of multi-functional speed sensor cables for high-speed trains. In summary, Example 1 is the best embodiment of this invention.

[0039] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above 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 one or more embodiments or examples.

[0040] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A polymer sheath material for a multi-functional speed sensor cable in high-speed trains, characterized in that, It is composed of the following raw materials in parts by weight: base resin: 75-88 parts; reinforcing and modifying materials: 6-12 parts; functional additives: 3.2-6.8 parts; environmental stabilizers: 2.5-4.5 parts; processing aids: 1.3-2.7 parts; The environmental stabilizer is composed of a composite antioxidant, an ultraviolet absorber, and an ozone stabilizer, wherein the composite antioxidant is 0.8-1.5 parts, the ultraviolet absorber is 0.9-1.6 parts, and the ozone stabilizer is 0.8-1.4 parts. The composite antioxidant is composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 1:1; the ultraviolet absorber is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole; and the ozone stabilizer is N-isopropyl-N'-phenyl-p-phenylenediamine.

2. The polymer sheath material for a multi-functional speed sensor cable for high-speed trains according to claim 1, characterized in that, The base resin is composed of polyether-type polyurethane elastomer and hydrogenated nitrile rubber, wherein the polyether-type polyurethane elastomer comprises 60-72 parts and the hydrogenated nitrile rubber comprises 15-16 parts.

3. The polymer sheath material for a multi-functional speed sensor cable for high-speed trains according to claim 2, characterized in that, The reinforcing and modified material is composed of nano-silicon nitride and aramid short-cut fibers, wherein the nano-silicon nitride comprises 2-4 parts and the aramid short-cut fibers comprise 4-8 parts.

4. The polymer sheath material for a multi-functional speed sensor cable for high-speed trains according to claim 3, characterized in that, The functional additive is composed of a halogen-free flame retardant, methylphenylsiloxane, and carbon nanotubes, wherein the halogen-free flame retardant comprises 1.5-3 parts, the methylphenylsiloxane comprises 1-2 parts, and the carbon nanotubes comprises 0.7-1.8 parts.

5. The polymer sheath material for a multi-functional speed sensor cable for high-speed trains according to claim 4, characterized in that, The processing aid is composed of calcium stearate, polyethylene wax and maleic anhydride graft compatibilizer, wherein the calcium stearate is 0.4-0.9 parts, the polyethylene wax is 0.3-0.8 parts, and the maleic anhydride graft compatibilizer is 0.6-1.0 parts.

6. The polymer sheath material for a multi-functional speed sensor cable for high-speed trains according to claim 5, characterized in that, The halogen-free flame retardant is composed of magnesium hydroxide and ammonium polyphosphate in a mass ratio of 3:2; the carbon nanotubes are multi-walled carbon nanotubes with a diameter of 10-20 nm and a length of 5-10 μm.

7. The preparation process of a polymer sheath material for a multi-functional speed sensor cable for high-speed trains according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Dry 60-72 parts of polyether-type polyurethane elastomer and 15-16 parts of hydrogenated nitrile rubber in a constant temperature drying oven at 60℃ for 4 hours to remove moisture; 2-4 parts of nano-silicon nitride are surface modified by silane coupling agent KH-550. Four to eight parts of aramid chopped staple fiber were dried at 120°C for 2 hours, with the moisture content controlled below 0.3%. All liquid additives should be stored at a constant temperature of 25±3℃ to prevent separation. S2. Add the dried base resin, modified reinforcing material, halogen-free flame retardant and carbon nanotubes from the functional additives, and environmental stabilizer to a high-speed mixer and mix in three stages: Coarse mixing: Stir at 800 rpm for 5 minutes to eliminate raw material accumulation; Fine mixing: Stir at 1200 r / min for 10 min, then add 1-2 parts of methylphenylsiloxane; Homogenization: Stir at 1500 r / min for 3 min, achieving a mixing uniformity of ≥99%; S3. Add 0.4-0.9 parts of processing aid calcium stearate, 0.3-0.8 parts of polyethylene wax, 0.6-1.0 parts of maleic anhydride graft compatibilizer and the mixture obtained in step S2 into a twin-screw extruder, set the temperature of each section of the extruder, and carry out melt blending extrusion at a screw speed of 350 r / min. The extrudate is then water-cooled and pelletized to obtain primary particles. S4. The primary particles are fed into a single-screw extruder for secondary plasticization. The barrel temperature is set to 160-170℃, the die head temperature to 165℃, and the screw speed to 280r / min. The material is extruded through the die to form a sheath blank. Nitrogen gas is used to protect the die outlet to prevent oxidation. S5. Place the sheath blank in a constant temperature and humidity curing chamber for post-treatment at 80℃ and 50% humidity for 8 hours to eliminate internal stress; then perform low-temperature aging treatment at -40℃ for 2 hours, and then allow it to naturally warm to room temperature. S6. Perform performance testing on the sheath material after step S5, and package it after it passes the test.

8. The preparation process of a polymer sheath material for a multi-functional speed sensor cable for high-speed trains according to claim 7, characterized in that, The performance testing items in step S6 include high and low temperature resistance, wear resistance, oil resistance, flame retardancy, and vibration fatigue resistance.

9. The preparation process of a polymer sheath material for a multi-functional speed sensor cable for high-speed trains according to claim 7, characterized in that, The temperatures of each section of the extruder in step S3 are 140°C for the feeding section, 160°C for the compression section, 175°C for the melting section, and 165°C for the die head section.

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