A low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for electric vehicle charging

Abstract

The application relates to the technical field of high-voltage cables of electric vehicles, in particular to a low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles. The low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles comprises a cable core and a low-smoke high-temperature-resistant polyolefin sheath layer wrapped outside the cable core; the raw materials of the low-smoke high-temperature-resistant polyolefin sheath layer comprise, by mass fraction, high-density polyethylene 80-120 parts, linear low-density polyethylene 10-40 parts, ethylene-vinyl acetate copolymer 10-30 parts, carboxyl-terminated butyl nitrile rubber 1-5 parts, carbon black 15-35 parts, graphene oxide 1-3 parts, silane coupling agent KH560 1.01-2.1 parts, crosslinking agent 1-2 parts, processing aid 2-8 parts, antioxidant 1-2 parts and light stabilizer 1-2 parts.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-voltage cables for electric vehicles, and particularly relates to a low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for electric vehicle charging. BACKGROUND

[0002] The new energy electric vehicle wire system can be divided into a high-voltage system and a low-voltage system. The high-voltage cable will generate electromagnetic wave influence on the signal transmission of the control line in the process of transmitting electric energy, and usually needs to increase a shielding layer outside the high-voltage line core. The new energy electric vehicle high-temperature-resistant charging and distribution shielding bus is crucial to the automobile cable.

[0003] According to the difference of the high-voltage cable sheath layer, the high-voltage cable can be divided into an oil-impregnated paper insulation high-voltage cable, a rubber insulation high-voltage cable and a cross-linked polyolefin high-voltage cable. The oil-impregnated paper insulation high-voltage cable is developed earlier, but is prone to oil droplet flow phenomenon. The rubber insulation high-voltage cable has many types, and the rubber has good softness and bending performance, but has poor ozone resistance and is mostly used for power cables of lower voltage grades.

[0004] The cross-linked polyolefin high-voltage cable has excellent comprehensive performance and good aging resistance, and has advantages in the environment of large load flow and high drop, but the bending part is prone to aging and cracking due to fatigue when bending, and the high-temperature resistance is poor, which needs to be solved urgently. SUMMARY

[0005] The present application relates to the technical field of high-voltage cables for electric vehicles, and particularly relates to a low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for electric vehicle charging.

[0006] A low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for electric vehicle charging, comprising a cable core and a low-smoke high-temperature-resistant polyolefin sheath layer wrapped outside the cable core; the raw materials of the low-smoke high-temperature-resistant polyolefin sheath layer comprise, by mass fraction, 80-120 parts of high-density polyethylene, 10-40 parts of linear low-density polyethylene, 10-30 parts of ethylene-vinyl acetate copolymer, 1-5 parts of carboxyl-terminated nitrile rubber, 15-35 parts of carbon black, 1-3 parts of graphene oxide, 1.01-2.1 parts of silane coupling agent KH560, 1-2 parts of cross-linking agent, 2-8 parts of processing aid, 1-2 parts of antioxidant and 1-2 parts of light stabilizer.

[0007] Preferably, the cross-linking agent is at least one of dicumyl peroxide, dibenzoyl peroxide and tert-butyl hydroperoxide.

[0008] Preferably, the processing aid is polyethylene wax or / and silicone powder.

[0009] Preferably, the antioxidant is at least one of antioxidant 1010, antioxidant BHT, antioxidant DNP and antioxidant TNP.

[0010] Preferably, the light stabilizer is at least one of light stabilizer 119, light stabilizer 292, light stabilizer 770, light stabilizer 944, light stabilizer M535.

[0011] The preparation method of the low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for electric vehicle charging comprises the following steps:

[0012] S1, carbon black and graphene oxide are added to anhydrous ethanol and ultrasonically treated for 1-2h, silane coupling agent KH560 is added, stirring is carried out at 60-80℃ for 1-2h, filtration, washing, drying and crushing are carried out to obtain pretreated carbon black;

[0013] S2, carboxyl-terminated nitrile rubber is added to the pretreated carbon black, homogenization treatment is carried out at 150-170℃ for 1-5min, mixing is carried out at a temperature of 80-95℃ for 1-2h, high-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, antioxidant, crosslinking agent, processing aid, carbon black, silane coupling agent KH560 and light stabilizer are added, and kneading is carried out at 80-95℃ for 20-30min to obtain a premix;

[0014] S3, the premix is extruded and coated outside the cable core, and drying is carried out.

[0015] Preferably, in S1, the ultrasonic frequency is 50-60kHz.

[0016] Preferably, the mass ratio of the carbon black used in S1 to the carbon black used in S2 is 10-20:5-15.

[0017] Preferably, the mass ratio of the silane coupling agent used in S1 to the silane coupling agent used in S2 is 0.01-0.1:1-2.

[0018] Preferably, in S3, a double-screw extruder is used for extrusion, and the temperature of each zone of the double-screw extruder is as follows: the first zone is 120-140℃, the second zone is 145-152℃, the third zone is 160-170℃, the fourth zone is 175-185℃, and the die head is 180-190℃.

[0019] Beneficial effects:

[0020] The high-voltage cable has excellent shielding effect, can resist 125℃ high temperature, has high tensile strength and excellent impact resistance, can meet the long-term use of new energy electric vehicles under harsh conditions, and is especially used for high-power shielding busbars for electric vehicle charging and power distribution, and has excellent prospects.

[0021] The application utilizes the combination of carbon black and graphene oxide, and has an organic adsorption layer on the surface of the carbon black and graphene oxide, so that the heat resistance and stability are high, the dispersibility in the matrix is effectively improved, the interface compatibility is better, the carboxyl in the carboxyl-terminated butylnitrile rubber is further reacted with the epoxy group, the butylnitrile copolymer segment is combined in the organic layer, when the external force impact is received, the molecular chain can be buffered, stress can be absorbed and dispersed, and the toughness of the polyethylene matrix is improved; meanwhile, under the action of the crosslinking agent, the polyethylene matrix can be entangled to form a more stable network structure, so that the high-temperature resistance of the polyethylene matrix is significantly improved, and the occurrence of fire accidents is reduced.

[0022] The application uses polyethylene as the main component, and uses carboxyl-terminated butylnitrile rubber, ethylene-vinyl acetate copolymer and other auxiliary materials to prepare the sheath layer, so that the high-voltage cable has excellent impact resistance and 125 DEG C high-temperature resistance, and the smoke suppression effect is remarkable.

[0023] The application uses polyolefin resin with excellent performance as the base material, the content of carbon black is low, the shielding effect of the obtained sheath layer is good, the cable has very good mechanical properties and anti-cracking properties, is suitable for high-voltage cable sheath layers with high requirements for mechanical properties, anti-cracking and high-temperature resistance, and can better ensure the normal use and operation of the cable. Meanwhile, the preparation process of the application is simple, the equipment investment is small, the efficiency is high, and the cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The tensile strength and impact strength of the polyolefin sheath layer of the high-voltage cable obtained in Example 5 and Comparative Examples 1-2 are compared.

[0025] Figure 2 The electromagnetic shielding efficiency of the high-voltage cable obtained in Example 5 and Comparative Examples 1-2 and the electromagnetic shielding efficiency retention rate after 125 DEG C heat treatment for 168 h are compared.

[0026] Figure 3 The tensile strength retention rate and impact strength retention rate of the polyolefin sheath layer of the high-voltage cable obtained in Example 5 and Comparative Examples 1-2 after 125 DEG C heat treatment for 168 h are compared.

[0027] Figure 4 The shrinkage rate of the polyolefin sheath layer of the high-voltage cable obtained in Example 5 and Comparative Examples 1-2 is compared. DETAILED DESCRIPTION

[0028] The application will be further described in combination with specific embodiments.

[0029] Example 1

[0030] The application discloses a low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles, which comprises a cable core and a low-smoke high-temperature-resistant polyolefin sheath layer covering the outer side of the cable core; the raw materials of the low-smoke high-temperature-resistant polyolefin sheath layer comprise 8000g of high-density polyethylene, 1000g of linear low-density polyethylene, 1000g of ethylene-vinyl acetate copolymer, 100g of carboxyl-terminated butyl nitrile rubber, 1500g of carbon black, 100g of graphene oxide, 101g of silane coupling agent KH560, 100g of dibenzoyl peroxide, 200g of silicone powder and 100g of antioxidant DNP and 100g of light stabilizer 119.

[0031] The application further discloses a preparation method of the low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles.

[0032] S1, 1000g of carbon black and graphene oxide are added into 5000g of anhydrous ethanol and ultrasonically treated for 1h, an ultrasonic frequency is 50kHz, 1g of silane coupling agent KH560 is added, stirring is carried out at a temperature of 60℃ for 1h, a stirring speed is 100r / min, filtration is carried out, washing is carried out with deionized water, vacuum drying is carried out, and crushing is carried out to obtain pretreated carbon black;

[0033] S2, carboxyl-terminated butyl nitrile rubber is added into the pretreated carbon black, high-speed homogenization is carried out at a temperature of 150℃ for 1min, a homogenization speed is 5000r / min, mixing is carried out at a temperature of 80℃ for 1h, the mixture is sent into a high-speed kneader, 500g of carbon black, 100g of silane coupling agent KH560, light stabilizer 119, high-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, antioxidant DNP, dibenzoyl peroxide and silicone powder are added, stirring is carried out at a speed of 300r / min for 20min, and a kneading temperature is 80℃, so as to obtain a premix;

[0034] S3, the premix is sent into a double-screw extruder to be extruded and coated on the outer side of the cable core, and is placed into a blast drying oven to be dried at a temperature of 80℃ for 2h.

[0035] In the application, the temperature of each zone of the double-screw extruder is as follows: the temperature of the first zone is 120℃, the temperature of the second zone is 145℃, the temperature of the third zone is 160℃, the temperature of the fourth zone is 175℃, and the temperature of the die head is 180℃.

[0036] Example 2

[0037] The application discloses a low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles, which comprises a cable core and a low-smoke high-temperature-resistant polyolefin sheath layer covering the outer side of the cable core; the raw materials of the low-smoke high-temperature-resistant polyolefin sheath layer comprise 12000g of high-density polyethylene, 4000g of linear low-density polyethylene, 3000g of ethylene-vinyl acetate copolymer, 500g of carboxyl-terminated butyl nitrile rubber, 3500g of carbon black, 300g of graphene oxide, 210g of silane coupling agent KH560, 200g of tert-butyl hydroperoxide, 800g of silicone powder, 200g of antioxidant TNP and 200g of light stabilizer 292.

[0038] The application further discloses a preparation method of the low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles.

[0039] S1, 2000g of carbon black and graphene oxide are added into 10000g of anhydrous ethanol and ultrasonically treated for 2h, an ultrasonic frequency is 60kHz, 10g of silane coupling agent KH560 is added, stirring is carried out at a temperature of 80℃ for 2h, a stirring speed is 500r / min, filtration is carried out, washing is carried out with deionized water, vacuum drying is carried out, and crushing is carried out to obtain pretreated carbon black;

[0040] S2, carboxyl-terminated butyl nitrile rubber is added into the pretreated carbon black, high-speed homogenization is carried out at a temperature of 170℃ for 5min, a homogenization speed is 10000r / min, mixing is carried out at a temperature of 95℃ for 2h, the mixture is sent into a high-speed kneader, 12000g of high-density polyethylene, 4000g of linear low-density polyethylene, 3000g of ethylene-vinyl acetate copolymer, 200g of antioxidant TNP, 200g of tert-butyl hydroperoxide, 800g of silicone powder, 1500g of carbon black, 200g of silane coupling agent KH560 and 200g of light stabilizer 292 are added, stirring is carried out at a speed of 600r / min for 30min, and a kneading temperature is 95℃, so as to obtain a premix;

[0041] S3, the premix is sent into a double-screw extruder to be extruded and coated on the outer side of the cable core, and the cable core is placed into a blast drying oven and dried at a temperature of 90℃ for 4h.

[0042] In the application, the temperature of each zone of the double-screw extruder is as follows: the temperature of the first zone is 140℃, the temperature of the second zone is 152℃, the temperature of the third zone is 170℃, the temperature of the fourth zone is 185℃, and the temperature of the die head is 190℃.

[0043] Example 3

[0044] The application discloses a low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles, which comprises a cable core and a low-smoke high-temperature-resistant polyolefin sheath layer covering the outer side of the cable core; the raw materials of the low-smoke high-temperature-resistant polyolefin sheath layer comprise 9000g of high-density polyethylene, 3000g of linear low-density polyethylene, 1500g of ethylene-vinyl acetate copolymer, 400g of carboxyl-terminated butyl nitrile rubber, 2600g of carbon black, 150g of graphene oxide, 178g of silane coupling agent KH560, 180g of dicumyl peroxide, 300g of polyethylene wax, 170g of antioxidant BHT and 120g of light stabilizer 770.

[0045] The application further discloses a preparation method of the low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles.

[0046] S1, 1800g of carbon black and graphene oxide are added into 7000g of anhydrous ethanol and ultrasonically treated for 100min, an ultrasonic frequency is 51kHz, 8g of silane coupling agent KH560 is added, stirring is carried out at a temperature of 65℃ for 100min, a stirring speed is 200r / min, filtration is carried out, washing is carried out with deionized water, vacuum drying is carried out, and crushing is carried out to obtain pretreated carbon black;

[0047] S2, carboxyl-terminated butyl nitrile rubber is added into the pretreated carbon black, high-speed homogenization is carried out at a temperature of 165℃ for 2min, a homogenization speed is 9000r / min, mixing is carried out at a temperature of 85℃ for 100min, the mixture is sent into a high-speed kneader, 9000g of high-density polyethylene, 3000g of linear low-density polyethylene, 1500g of ethylene-vinyl acetate copolymer, 170g of antioxidant BHT, 180g of dicumyl peroxide, 300g of polyethylene wax, 800g of carbon black, 170g of silane coupling agent KH560 and 120g of light stabilizer 770 are added, stirring is carried out at a speed of 400r / min for 28min, and a kneading temperature is 85℃, so as to obtain a premix;

[0048] S3, the premix is sent into a double-screw extruder to be extruded and coated on the outer side of the cable core, and is placed into a blast drying oven to be dried at a temperature of 88℃ for 2.5h;

[0049] In the application, the temperature of each zone of the double-screw extruder is as follows: the temperature of the first zone is 135℃, the temperature of the second zone is 146℃, the temperature of the third zone is 168℃, the temperature of the fourth zone is 178℃, and the temperature of the die head is 188℃.

[0050] Example 4

[0051] The application discloses a low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles, which comprises a cable core and a low-smoke high-temperature-resistant polyolefin sheath layer covering the outer side of the cable core; the raw materials of the low-smoke high-temperature-resistant polyolefin sheath layer comprise 11000g of high-density polyethylene, 2000g of linear low-density polyethylene, 2500g of ethylene-vinyl acetate copolymer, 200g of carboxyl-terminated butyl nitrile rubber, 2400g of carbon black, 250g of graphene oxide, 132g of silane coupling agent KH560, 120g of dicumyl peroxide, 700g of polyethylene wax, 130g of antioxidant BHT and 180g of light stabilizer M535.

[0052] The application further discloses a preparation method of the low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles.

[0053] S1, 1200g of carbon black and graphene oxide are added into 9000g of anhydrous ethanol and ultrasonically treated for 80min, an ultrasonic frequency is 57kHz, 2g of silane coupling agent KH560 is added, stirring is carried out at a temperature of 75℃ for 80min, a stirring speed is 400r / min, filtration is carried out, washing is carried out with deionized water, vacuum drying is carried out, and crushing is carried out to obtain pretreated carbon black;

[0054] S2, carboxyl-terminated butyl nitrile rubber is added into the pretreated carbon black, high-speed homogenization is carried out at a temperature of 155℃ for 4min, a homogenization speed is 7000r / min, mixing is carried out at a temperature of 90℃ for 80min, the mixture is sent into a high-speed kneader, high-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, antioxidant BHT, dicumyl peroxide, polyethylene wax, 1200g of carbon black, 130g of silane coupling agent KH560 and light stabilizer M535 are added, stirring is carried out at a speed of 500r / min for 22min, and a kneading temperature is 90℃, so as to obtain a premix;

[0055] S3, the premix is sent into a double-screw extruder to be extruded and coated on the outer side of the cable core, and is placed into a blowing drying box to be dried at a temperature of 82℃ for 3.5h.

[0056] In the application, the temperature of each zone of the double-screw extruder is as follows: 125℃ for the first zone, 150℃ for the second zone, 162℃ for the third zone, 182℃ for the fourth zone and 182℃ for the die head.

[0057] Example 5

[0058] The application discloses a low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles, which comprises a cable core and a low-smoke high-temperature-resistant polyolefin sheath layer covering the outer side of the cable core; the raw materials of the low-smoke high-temperature-resistant polyolefin sheath layer comprise 10000g of high-density polyethylene, 2500g of linear low-density polyethylene, 2000g of ethylene-vinyl acetate copolymer, 300g of carboxyl-terminated butyl nitrile rubber, 2500g of carbon black, 200g of graphene oxide, 155g of silane coupling agent KH560, 150g of dicumyl peroxide, 500g of polyethylene wax, 150g of antioxidant 1010 and 150g of light stabilizer 944.

[0059] The application further discloses a preparation method of the low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles.

[0060] S1, 1500g of carbon black and graphene oxide are added into 8000g of anhydrous ethanol and ultrasonically treated for 90min, an ultrasonic frequency is 54kHz, 5g of silane coupling agent KH560 is added, stirring is carried out at a temperature of 70℃ for 90min, a stirring speed is 300r / min, filtration is carried out, washing is carried out with deionized water, vacuum drying is carried out, and crushing is carried out to obtain pretreated carbon black;

[0061] S2, carboxyl-terminated butyl nitrile rubber is added into the pretreated carbon black, high-speed homogenization is carried out at a temperature of 160℃ for 3min, a homogenization speed is 8000r / min, mixing is carried out at a temperature of 88℃ for 90min, the mixture is sent into a high-speed kneader, 1000g of carbon black, 150g of silane coupling agent KH560, light stabilizer 944, high-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, antioxidant 1010 and dicumyl peroxide and polyethylene wax are added, stirring is carried out at a speed of 450r / min for 25min, and a kneading temperature is 88℃, so as to obtain a premix;

[0062] S3, the premix is sent into a double-screw extruder to be extruded and coated on the outer side of the cable core, and is placed into a blowing drying box to be dried at a temperature of 85℃ for 3h.

[0063] In the application, the temperature of each zone of the double-screw extruder is as follows: the temperature of the first zone is 130℃, the temperature of the second zone is 148℃, the temperature of the third zone is 165℃, the temperature of the fourth zone is 180℃, and the temperature of the die head is 185℃.

[0064] Comparative example 1

[0065] The application discloses a low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles, which comprises a cable core and a low-smoke high-temperature-resistant polyolefin sheath layer wrapped outside the cable core.

[0066] The application further discloses a preparation method of the low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles.

[0067] S1, carboxyl-terminated butyl nitrile rubber is added to pretreated carbon black, high-speed homogenization is carried out at a temperature of 160 DEG C for 3 min, the homogenization speed is 8000 r / min, mixing is carried out at a temperature of 88 DEG C for 90 min, the mixture is sent into a high-speed kneader, high-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, antioxidant 1010, dicumyl peroxide, polyethylene wax, carbon black, graphene oxide, silane coupling agent KH560 and light stabilizer 944 are added, stirring is carried out at a speed of 450 r / min for 25 min, the kneading temperature is 88 DEG C, and a premix is obtained.

[0068] S2, the premix is sent into a double-screw extruder to be extruded and wrapped outside the cable core, and is placed into a forced air drying oven to be dried at a temperature of 85 DEG C for 3 h.

[0069] The temperature of each zone of the double-screw extruder is as follows: 130 DEG C for the first zone, 148 DEG C for the second zone, 165 DEG C for the third zone, 180 DEG C for the fourth zone and 185 DEG C for the die head.

[0070] Comparative example 2

[0071] The application discloses a low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles, which comprises a cable core and a low-smoke high-temperature-resistant polyolefin sheath layer wrapped outside the cable core.

[0072] The application further discloses a preparation method of the low-smoke high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles.

[0073] S1, 1500 g of carbon black and graphene oxide were added to 8000 g of anhydrous ethanol and ultrasonically treated for 90 min at an ultrasonic frequency of 54 kHz, 5 g of silane coupling agent KH560 was added, and stirring was performed at a temperature of 70℃ for 90 min at a stirring speed of 300 r / min, then filtered, washed with deionized water, vacuum dried, and pulverized to obtain pretreated carbon black;

[0074] S2, the pretreated carbon black and carboxyl-terminated nitrile rubber were fed into a high-speed kneader, 1000 g of carbon black, 150 g of silane coupling agent KH560, light stabilizer 944, high-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, antioxidant 1010, and dicumyl peroxide were added, and stirring was performed at a speed of 450 r / min for 25 min at a kneading temperature of 88℃ to obtain a premix;

[0075] S3, the premix was fed into a double-screw extruder to be extruded and coated on the outside of the cable core, and placed in a forced air drying oven to be dried at a temperature of 85℃ for 3 h;

[0076] The temperature of each zone of the double-screw extruder was as follows: 130℃ for zone 1, 148℃ for zone 2, 165℃ for zone 3, 180℃ for zone 4, and 185℃ for the head.

[0077] The polyolefin sheath layer of the high-voltage cable obtained in Example 5 and Comparative Examples 1-2 was peeled off, the tensile strength was determined according to GB / T2951.11-2008 "Cables and optical fibers - Insulation and sheath materials - General test methods - Part 11: General test methods - Measurement of thickness and outer dimensions - Mechanical property tests", and the impact strength was determined according to GB / T 1843-2008 "Determination of the Izod impact strength of plastics".

[0078] As shown in Figure 1 , the tensile strength and impact strength of the polyolefin sheath layer of the high-voltage cable obtained in Example 5 were the highest, and were better than those of Comparative Examples 1-2 (P<0.05).

[0079] The electromagnetic shielding efficiency of the high-voltage cable obtained in Example 5 and Comparative Examples 1-2 was tested in a wide frequency range of 4-18 GHz. Then each group of samples was heat treated at 125℃ for 168 h, and the electromagnetic shielding efficiency retention rate was tested again.

[0080] As shown in Figure 2 , the electromagnetic shielding efficiency of the high-voltage cable obtained in Example 5 was the highest, and was better than that of Comparative Examples 1-2 (P<0.05); after heat treatment at 125℃ for 168 h, the electromagnetic shielding efficiency retention rate was still the highest, and was better than that of Comparative Examples 1-2 (P<0.05).

[0081] The high-voltage cable obtained in Example 5 and Comparative Examples 1-2 was heat treated in an environment of 125 DEG C for 168 h, and then the polyolefin sheath layer was stripped, and the tensile strength retention rate and impact strength retention rate were tested again.

[0082] As shown in Table 2, the high-voltage cable obtained in Example 5 still has the highest tensile strength retention rate and impact strength retention rate of the polyolefin sheath layer after being heat treated at 125 DEG C for 168 h, and is superior to Comparative Examples 1-2 (P < 0.05). Figure 3

[0083] The anti-shrinkage performance of the high-voltage cable obtained in Example 5 and Comparative Examples 1-2 was determined according to GB / T 2951.13-2008 "Cables and optical fibers - Electrical insulating materials and supertaining materials - Determination of the density - Determination of the water absorption - Determination of the shrinkage".

[0084] As shown in Table 3, the high-voltage cables obtained in Example 5 and Comparative Examples 1-2 have low shrinkage rates, and there is no significant difference (P > 0.05). Figure 4

[0085] Since the shielding effect of the high-voltage cable obtained in Example 5 and the mechanical properties of the sheath layer thereof are the best, the bunching flame-retardant performance and low-smoke performance of the high-voltage cable obtained in Example 5 were determined according to GB / T 19666-2019 "Flame-retardant and fire-resistant electrical wires, cables or optical fibers - General requirements". The high-voltage cable obtained in Example 5 meets the requirements of flame-retardant Class A and low smoke.

[0086] The applicant believes that: this is because the application utilizes carbon black and graphene oxide to be compounded, and an organic adsorption layer is combined on the surface, which not only has high heat-resistant stability, but also effectively improves the dispersibility in the matrix and has better interface compatibility, and the carboxyl groups in the carboxyl-terminated butylnitrile rubber further react with the epoxy groups, and the butylnitrile copolymer segments are combined in the organic layer, when subjected to external force impact, the molecular chains can be buffered, stress can be absorbed and dispersed, and the toughness of the polyethylene matrix is improved; meanwhile, under the action of the crosslinking agent, entanglement with the polyethylene matrix can occur, and a more stable network structure is formed, and the high-temperature resistance of the polyethylene matrix is significantly improved, and the occurrence of fire accidents is reduced. The application takes polyethylene as the main component, and the sheath layer is prepared by compounding carboxyl-terminated butylnitrile rubber, ethylene-vinyl acetate copolymer and other auxiliary materials, so that the high-voltage cable has excellent impact resistance and 125 DEG C high-temperature resistance, and the smoke suppression effect is remarkable.

[0087] The above describes only the preferred specific embodiments of the application, but the protection scope of the application is not limited thereto, and any person skilled in the art can make equivalent replacements or changes to the technical solutions and inventive concepts of the application within the technical scope disclosed by the application, which should be covered within the protection scope of the application.​​

Claims

1. A low smoke, high temperature resistant polyolefin jacketed high voltage cable for electric vehicle charging, characterized in that, The low-smoke and high-temperature-resistant polyolefin sheath layer comprises a cable core and a low-smoke and high-temperature-resistant polyolefin sheath layer wrapped outside the cable core. The low-smoke and high-temperature-resistant polyolefin sheath layer raw material comprises, by mass fraction, 80-120 parts of high-density polyethylene, 10-40 parts of linear low-density polyethylene, 10-30 parts of ethylene-vinyl acetate copolymer, 1-5 parts of carboxyl-terminated butyl nitrile rubber, 15-35 parts of carbon black, 1-3 parts of graphene oxide, 1.01-2.1 parts of silane coupling agent KH560, 1-2 parts of crosslinking agent, 2-8 parts of processing aid, 1-2 parts of antioxidant, and 1-2 parts of light stabilizer. The crosslinking agent is at least one of dicumyl peroxide, dibenzoyl peroxide, and tert-butyl hydroperoxide. The preparation method of the low-smoke and high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles comprises the following steps: In S1, the carbon black and the graphene oxide are added to anhydrous ethanol and ultrasonically treated for 1-2 hours, the silane coupling agent KH560 is added, and stirring is performed at 60-80°C for 1-2 hours, followed by filtration, washing, drying, and crushing to obtain pretreated carbon black. In S2, the carboxyl-terminated butyl nitrile rubber is added to the pretreated carbon black, homogenization treatment is performed at 150-170°C for 1-5 minutes, mixing is performed at a temperature of 80-95°C for 1-2 hours, the high-density polyethylene, the linear low-density polyethylene, the ethylene-vinyl acetate copolymer, the antioxidant, the crosslinking agent, the processing aid, the carbon black, the silane coupling agent KH560, and the light stabilizer are added, and kneading is performed at 80-95°C for 20-30 minutes to obtain a premix. In S1, the ultrasonic frequency is 50-60 kHz. The processing aid is polyethylene wax or / and silicone powder. The antioxidant is at least one of antioxidant 1010, antioxidant BHT, antioxidant DNP, and antioxidant TNP.

2. The low smoke, high temperature resistant polyolefin jacketed high voltage cable for electric vehicle charging of claim 1, wherein, The light stabilizer is at least one of light stabilizer 119, light stabilizer 292, light stabilizer 770, light stabilizer 944, and light stabilizer M535.

3. The low smoke, high temperature resistant polyolefin jacketed high voltage cable for electric vehicle charging of claim 1, wherein, The preparation method of the low-smoke and high-temperature-resistant polyolefin sheath high-voltage cable for charging electric vehicles comprises the following steps:

4. The low smoke, high temperature resistant polyolefin jacketed high voltage cable for electric vehicle charging of claim 1, wherein, In S1, the carbon black and the graphene oxide are added to anhydrous ethanol and ultrasonically treated for 1-2 hours, the silane coupling agent KH560 is added, and stirring is performed at 60-80°C for 1-2 hours, followed by filtration, washing, drying, and crushing to obtain pretreated carbon black.

5. A process for the preparation of a low smoke high temperature resistant polyolefin jacketed high voltage cable for electric vehicle charging as claimed in any one of claims 1 to 4, characterized in that, In S2, the carboxyl-terminated butyl nitrile rubber is added to the pretreated carbon black, homogenization treatment is performed at 150-170°C for 1-5 minutes, mixing is performed at a temperature of 80-95°C for 1-2 hours, the high-density polyethylene, the linear low-density polyethylene, the ethylene-vinyl acetate copolymer, the antioxidant, the crosslinking agent, the processing aid, the carbon black, the silane coupling agent KH560, and the light stabilizer are added, and kneading is performed at 80-95°C for 20-30 minutes to obtain a premix. In S1, the ultrasonic frequency is 50-60 kHz. The processing aid is polyethylene wax or / and silicone powder. The antioxidant is at least one of antioxidant 1010, antioxidant BHT, antioxidant DNP, and antioxidant TNP. The light stabilizer is at least one of light stabilizer 119, light stabilizer 292, light stabilizer 770, light stabilizer 944, and light stabilizer M535. ​ 6. The process for the preparation of a low smoke, high temperature resistant polyolefin jacketed high voltage cable for electric vehicle charging as claimed in claim 5 wherein, ​ ​ 7. The process for the preparation of a low smoke, high temperature resistant polyolefin jacketed high voltage cable for electric vehicle charging as claimed in claim 5 wherein, S3 was extruded by twin-screw extruder, the temperature of each zone of the twin-screw extruder was as follows: 120-140℃ for the first zone, 145-152℃ for the second zone, 160-170℃ for the third zone, 175-185℃ for the fourth zone, and 180-190℃ for the head. ​

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