High voltage cables for new energy vehicles

Abstract

The present invention belongs to the field of cable technology, and specifically relates to a high-voltage cable for new energy vehicles, including a conductor and an insulating layer; the insulating layer material is made of the following raw materials by mass: 40-50 parts of polyethylene, 5-10 parts of β-caryophyllene-maleic anhydride-polyethylene copolymer, 10-15 parts of ethylene-octene copolymer, 1-4 parts of composite crosslinking agent, 2-3 parts of cellulose nanofibers, 1-2 parts of kaurene, 5-10 parts of flame retardant, 0.5-1 parts of toughening agent, and 0.5-1 parts of lubricant. The cable prepared by the present invention has excellent thermal stability, mechanical strength and insulation performance, and effectively improves the service life and stability of the cable.

Description

Technical Field

[0001] The present invention belongs to the technical field of cables, and in particular relates to a high-voltage cable for new energy vehicles. Background Art

[0002] Cable is a device for transmitting electric energy or signals. It is usually made of one or more mutually insulated conductors and insulating layers. It transmits electricity or information from one place to another. It is an indispensable part of modern power, communication and other systems. With the changes in the use environment of cables, the requirements for the insulation, flame retardancy and other properties of cables are becoming higher and higher. Traditional cable materials are mostly polyvinyl chloride (PVC), which is difficult to meet the use requirements.

[0003] A Chinese patent application document with publication number CN114822960A discloses a medium-voltage copper core power cable with good insulation. The sheath material of the cable includes the following components: polyvinyl chloride, modified nano-calcium carbonate, aluminum hydroxide, nylon, hollow glass microspheres, and di(p-nitrophenyl)phosphonic acid azidoate. Aluminum hydroxide is added to the insulating sheath layer to improve the flame retardancy and insulation of the sheath. The coordinated use of hollow glass microspheres and di(p-nitrophenyl)phosphonic acid azidoate avoids the problem of reduced mechanical properties caused by the addition of aluminum hydroxide.

[0004] However, with the development of new energy vehicles, the voltage level of the high-voltage system is getting higher and higher. Polyvinyl chloride is a polar material with polar groups in its molecules, which cannot meet the strict requirements of the high-voltage system for cable insulation and voltage resistance. Summary of the invention

[0005] Existing cables have the problem of low insulation under high voltage conditions; in order to solve this problem, the present invention provides a high-voltage cable for new energy vehicles.

[0006] In order to achieve the purpose of the present invention, the present invention adopts the following technical solutions:

[0007] The present invention provides a high-voltage cable for new energy vehicles, comprising a conductor and an insulating layer;

[0008] The insulating layer material is made of the following raw materials in parts by mass: 40-50 parts of polyethylene, 10-15 parts of ethylene-octene copolymer, 5-10 parts of β-caryophyllene-maleic anhydride-polyethylene copolymer, 1-4 parts of composite cross-linking agent, 2-3 parts of cellulose nanofibers, 1-2 parts of kaurene, 5-10 parts of flame retardant, 0.5-1 part of toughening agent and 0.5-1 part of lubricant.

[0009] Preferably, the composite cross-linking agent is prepared by mixing di-tert-butyl peroxyisopropylbenzene and di-tert-butyl peroxide in a mass ratio of (3-4):1.

[0010] Preferably, the method for preparing the cellulose nanofibers comprises the following steps:

[0011] (1) treating Masson pine powder with alkali, mixing it evenly with a hydrogen peroxide solution, filtering, washing, and drying to obtain cellulose;

[0012] (2) The cellulose and the composite acid are mixed evenly, filtered, washed, the washed slurry is homogenized, and dried to obtain cellulose nanofibers.

[0013] Preferably, in step (1), the alkali treatment is to react the Masson pine powder with a sodium hydroxide aqueous solution at 60-80° C. for 4-8 hours;

[0014] The ratio of Masson pine powder to sodium hydroxide aqueous solution is 1g:15-20mL, and the concentration of sodium hydroxide aqueous solution is 0.2-0.5mol / L.

[0015] Preferably, in step (2), the ratio of cellulose to composite acid is 1 g: 30-80 mL; the mixing temperature is 70-100° C.;

[0016] The composite acid is prepared by mixing citric acid and hydrochloric acid in a mass ratio of (2-4):1.

[0017] By adopting the above technical solution, after citric acid and hydrochloric acid are mixed, the acidic environment is strengthened, thereby accelerating the starting speed of the hydrolysis reaction.

[0018] Preferably, the preparation method of the β-caryophyllene-maleic anhydride-polyethylene copolymer comprises the following steps:

[0019] β-caryophyllene, maleic anhydride, polyethylene, di-tert-butyl peroxide and cyclohexanone are mixed uniformly, heated under a nitrogen atmosphere for reaction, cooled to room temperature, and dichloromethane is added and mixed uniformly to obtain a mixed solution, and the mixed solution is poured into methanol to precipitate, filtered, washed, and dried to obtain a β-caryophyllene-maleic anhydride-polyethylene copolymer;

[0020] The mass ratio of the β-caryophyllene, maleic anhydride and polyethylene is (2-5):1:1.

[0021] By adopting the above technical solution, the ratio of β-caryophyllene, maleic anhydride and polyethylene is optimized and adjusted, so that the monomer unit sequence of the β-caryophyllene-maleic anhydride-polyethylene copolymer is evenly distributed and has good thermal stability.

[0022] Preferably, the temperature of the temperature-raising reaction is 130-150° C., and the time of the temperature-raising reaction is 2-4 hours.

[0023] Preferably, the method for preparing the insulating layer material comprises the following steps:

[0024] Put polyethylene, ethylene-octene copolymer and kaurene into an internal mixer, heat up to soften, add the composite cross-linking agent into the internal mixer and mix for 5-10 minutes, then add cellulose nanofiber, flame retardant, toughening agent and lubricant, heat up to 130-150℃, extrude and shape to obtain insulation layer material.

[0025] Preferably, the temperature for the heating and softening is 120-140° C., and the time for the heating and softening is 10-20 min.

[0026] Preferably, the conductor is formed by twisting a plurality of metal cores; an inner semiconductive layer, an insulating layer, an outer semiconductive layer, a shielding layer and an outer sheath are sequentially coated along the axial direction of the conductor itself.

[0027] Preferably, the metal core is a copper core.

[0028] In summary, the beneficial effects of the present invention are:

[0029] (1) The present invention introduces cellulose nanofibers into the insulation layer material. The cellulose nanofibers have good insulation properties and can increase the insulation resistance of the insulation layer material. The cellulose nanofibers have extremely high aspect ratio and specific surface area and low thermal expansion coefficient. The addition of cellulose nanofibers reduces the size change of the cable insulation layer, reduces the internal stress caused by thermal expansion and contraction, and helps to improve the problems of cracking and delamination of the insulation layer.

[0030] (2) The present invention introduces kaurene into the insulating layer material, thereby improving the thermal stability, mechanical strength and insulation performance of the cable material; kaurene is composed of multiple six-membered rings, which makes kaurene have good chemical stability and heat resistance; the double bonds and other groups existing in kaurene participate in the cross-linking reaction of polyethylene and other substances, fill in the molecular gaps of the polyethylene cross-linked product, and form a dense cross-linked network, which can effectively improve the strength of the cable material; the molecular structure of kaurene has a relatively large energy gap, which can inhibit the flow of current and improve the insulation performance of the cable material;

[0031] (3) The present invention uses a composite cross-linking agent to cross-link polyethylene to form an insulating layer material. The composite cross-linking agent has multiple peroxy groups, which can accelerate the cross-linking reaction speed, improve the degree of cross-linking reaction, reduce the generation of by-products, reduce impurities inside the insulating layer material, enhance the breakdown resistance of the insulating layer material, and enhance the insulation of the insulating layer material;

[0032] (4) The present invention introduces β-caryophyllene-maleic anhydride-polyethylene copolymer and ethylene-octene copolymer into the insulating layer material, thereby enhancing the cross-linking degree of polyethylene, forming a denser cross-linking network, and improving the mechanical strength and thermal stability of the insulating layer material; the cable prepared by the present invention has excellent thermal stability, mechanical strength and insulation performance, effectively improving the service life and stability of the cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the infrared spectrum of the β-caryophyllene-maleic anhydride-polyethylene copolymer in Example 1 of the present invention. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is explained in detail below with reference to several representative embodiments of the present invention.

[0035] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples are all commercially available unless otherwise specified.

[0036] In the following embodiments, the inner semiconductive layer and the outer semiconductive layer are both made of EPDM rubber, the shielding layer is made of copper wire mesh, the outer sheath is made of TPE, the flame retardant is BT-93W, the toughening agent is styrene-butadiene-styrene block copolymer, and the lubricant is lubricant PE-Wax.

[0037] Example 1

[0038] The high-voltage cable for new energy vehicles of this embodiment is a conductor formed by twisting a metal copper core, and an inner semi-conductive layer, an insulating layer, an outer semi-conductive layer, a shielding layer and an outer sheath are sequentially coated along the axial direction of the conductor itself.

[0039] The insulating layer material of this embodiment is made of the following raw materials: 40 kg of polyethylene, 15 kg of ethylene-octene copolymer, 10 kg of β-caryophyllene-maleic anhydride-polyethylene copolymer, 3.2 kg of di-tert-butyl peroxyisopropylbenzene, 0.8 kg of di-tert-butyl peroxide, 2 kg of cellulose nanofibers, 2 kg of kaurene, 5 kg of flame retardant, 1 kg of toughening agent, and 0.7 kg of lubricant.

[0040] The specific steps of the method for preparing the insulating layer material of this embodiment are as follows:

[0041] S1: Preparation of cellulose nanofibers

[0042] (1) Add 50 g of Masson pine powder to 0.75 L of 0.3 mol / L sodium hydroxide aqueous solution, heat to 65 °C and stir for 6 h, filter, wash, freeze-dry at -50 °C for 8 h, grind to 500 mesh, take 10 g and stir with 1 L of 30% hydrogen peroxide solution at 80 °C for 10 h, filter, wash, freeze-dry at -50 °C for 8 h to obtain cellulose;

[0043] (2) Add 10 g of cellulose to a mixed solution of 375 mL of 80% citric acid and 125 mL of 37% hydrochloric acid, heat to 80 °C, stir evenly, filter, wash, transfer the washed slurry to a homogenizer, homogenize 10 times at 150 MPa, and freeze-dry at -50 °C for 8 h to obtain cellulose nanofibers;

[0044] S2: Preparation of β-caryophyllene-maleic anhydride-polyethylene copolymer

[0045] 20 g of β-caryophyllene, 10 g of maleic anhydride, 10 g of polyethylene, 1 g of di-tert-butyl peroxide and 100 mL of cyclohexanone were stirred evenly, heated to 130° C. under a nitrogen atmosphere for reaction for 3 h, cooled to room temperature, added with dichloromethane and stirred evenly to obtain a mixed solution, poured the mixed solution into methanol, precipitated, filtered, washed, and dried to obtain a β-caryophyllene-maleic anhydride-polyethylene copolymer;

[0046] The β-caryophyllene-maleic anhydride-polyethylene copolymer prepared in Example 1 was tested by an infrared spectrometer to obtain its infrared spectrum. Figure 1 As shown. Combined Figure 1 It can be seen that the characteristic absorption peak of maleic anhydride monomer (697cm -1 、1596cm -1 and 1060cm -1 ) did not appear; 1720cm -1 and 1782cm -1 The C=O stretching vibration absorption peaks of maleic anhydride appeared at 3068cm and 3069cm, respectively, indicating that maleic anhydride and polyethylene undergo cross-linking reaction. -1 The CH stretching vibration absorption peak of olefins at 1631 cm -1 The C=C stretching vibration absorption peak at β-caryophyllene indicates that the double bond in β-caryophyllene participates in the cross-linking reaction. The infrared spectrum proves that maleic anhydride, β-caryophyllene and polyethylene react to form β-caryophyllene-maleic anhydride-polyethylene copolymer;

[0047] S3: Preparation of insulation layer materials

[0048] Polyethylene, ethylene-octene copolymer, β-caryophyllene-maleic anhydride-polyethylene copolymer and kaurene are put into an internal mixer, heated to 120°C and softened for 15 minutes, di-tert-butyl peroxyisopropylbenzene and di-tert-butyl peroxide are added into the internal mixer and kneaded for 10 minutes, and then cellulose nanofibers, flame retardant, toughening agent and lubricant are added, the temperature is raised to 150°C, and extrusion is performed to obtain an insulating layer material.

[0049] Example 2

[0050] The high-voltage cable for new energy vehicles of this embodiment is a conductor formed by twisting a metal copper core, and an inner semi-conductive layer, an insulating layer, an outer semi-conductive layer, a shielding layer and an outer sheath are sequentially coated along the axial direction of the conductor itself.

[0051] The insulating layer material of this embodiment is made of the following raw materials: 45kg of polyethylene, 15kg of ethylene-octene copolymer, 10kg of β-caryophyllene-maleic anhydride-polyethylene copolymer, 2.4kg of di-tert-butyl peroxyisopropylbenzene, 0.6kg of di-tert-butyl peroxide, 3kg of cellulose nanofibers, 1kg of kaurene, 10kg of flame retardant, 0.7kg of toughening agent, and 0.5kg of lubricant.

[0052] The specific steps of the method for preparing the insulating layer material of this embodiment are as follows:

[0053] S1: Preparation of cellulose nanofibers

[0054] (1) Add 50 g of Masson pine powder to 0.9 L of 0.2 mol / L sodium hydroxide aqueous solution, heat to 60 °C and stir for 4 h, filter, wash, freeze-dry at -50 °C for 8 h, grind to 500 mesh, take 10 g and mix with 1 L of 30% hydrogen peroxide solution, stir at 80 °C for 10 h, filter, wash, freeze-dry at -50 °C for 8 h to obtain cellulose;

[0055] (2) Add 10 g of cellulose to a mixed solution of 200 mL of 80% citric acid and 100 mL of 37% hydrochloric acid, heat to 70 °C, stir evenly, filter, wash, transfer the washed slurry to a homogenizer, homogenize 10 times at 150 MPa, and freeze-dry at -50 °C for 8 h to obtain cellulose nanofibers;

[0056] S2: Preparation of β-caryophyllene-maleic anhydride-polyethylene copolymer

[0057] 30 g of β-caryophyllene, 10 g of maleic anhydride, 10 g of polyethylene, 1 g of di-tert-butyl peroxide and 100 mL of cyclohexanone were stirred evenly, heated to 140° C. for reaction for 2 h under a nitrogen atmosphere, cooled to room temperature, and dichloromethane was added and stirred evenly to obtain a mixed solution, the mixed solution was poured into methanol, a precipitate was precipitated, filtered, washed, and dried to obtain a β-caryophyllene-maleic anhydride-polyethylene copolymer;

[0058] S3: Preparation of insulation layer materials

[0059] Polyethylene, ethylene-octene copolymer, β-caryophyllene-maleic anhydride-polyethylene copolymer and kaurene are put into an internal mixer, heated to 140°C and softened for 10 minutes, di-tert-butyl peroxyisopropylbenzene and di-tert-butyl peroxide are added into the internal mixer and kneaded for 5 minutes, and then cellulose nanofibers, flame retardant, toughening agent and lubricant are added, the temperature is raised to 130°C, and extrusion is performed to obtain an insulating layer material.

[0060] Example 3

[0061] The high-voltage cable for new energy vehicles of this embodiment is a conductor formed by twisting a metal copper core, and an inner semi-conductive layer, an insulating layer, an outer semi-conductive layer, a shielding layer and an outer sheath are sequentially coated along the axial direction of the conductor itself.

[0062] The insulating layer material of this embodiment is made of the following raw materials: 50kg of polyethylene, 10kg of ethylene-octene copolymer, 8kg of β-caryophyllene-maleic anhydride-polyethylene copolymer, 0.75kg of di-tert-butyl peroxyisopropylbenzene, 0.25kg of di-tert-butyl peroxide, 3kg of cellulose nanofibers, 2kg of kaurene, 10kg of flame retardant, 0.5kg of toughening agent, and 1kg of lubricant.

[0063] The specific steps of the method for preparing the insulating layer material of this embodiment are as follows:

[0064] S1: Preparation of cellulose nanofibers

[0065] (1) Add 50 g of Masson pine powder to 1 L of 0.3 mol / L sodium hydroxide aqueous solution, heat to 80 °C and stir for 6 h, filter, wash, freeze-dry at -50 °C for 8 h, grind to 500 mesh, take 10 g and add 1 L of 30% hydrogen peroxide solution, stir at 80 °C for 10 h, filter, wash, freeze-dry at -50 °C for 8 h to obtain cellulose;

[0066] (2) Add 10 g of cellulose to a mixed solution of 640 mL of 80% citric acid and 160 mL of 37% hydrochloric acid, heat to 90 °C, stir evenly, filter, wash, transfer the washed slurry to a homogenizer, homogenize 10 times at 150 MPa, and freeze-dry at -50 °C for 8 h to obtain cellulose nanofibers;

[0067] S2: Preparation of β-caryophyllene-maleic anhydride-polyethylene copolymer

[0068] 40 g of β-caryophyllene, 10 g of maleic anhydride, 10 g of polyethylene, 1 g of di-tert-butyl peroxide and 100 mL of cyclohexanone were stirred evenly, heated to 150° C. for reaction for 2 h under a nitrogen atmosphere, cooled to room temperature, and dichloromethane was added and stirred evenly to obtain a mixed solution, the mixed solution was poured into methanol, a precipitate was precipitated, filtered, washed, and dried to obtain a β-caryophyllene-maleic anhydride-polyethylene copolymer;

[0069] S3: Preparation of insulation layer materials

[0070] Polyethylene, ethylene-octene copolymer, β-caryophyllene-maleic anhydride-polyethylene copolymer and kaurene are put into an internal mixer, heated to 130°C and softened for 15 minutes, di-tert-butyl peroxyisopropylbenzene and di-tert-butyl peroxide are added into the internal mixer and kneaded for 8 minutes, and then cellulose nanofibers, flame retardant, toughening agent and lubricant are added, the temperature is raised to 140°C, and extrusion is performed to obtain an insulating layer material.

[0071] Example 4

[0072] The high-voltage cable for new energy vehicles of this embodiment is a conductor formed by twisting a metal copper core, and an inner semi-conductive layer, an insulating layer, an outer semi-conductive layer, a shielding layer and an outer sheath are sequentially coated along the axial direction of the conductor itself.

[0073] The insulating layer material of this embodiment is made of the following raw materials: 45 kg of polyethylene, 13 kg of ethylene-octene copolymer, 5 kg of β-caryophyllene-maleic anhydride-polyethylene copolymer, 1.5 kg of di-tert-butyl peroxyisopropylbenzene, 0.5 kg of di-tert-butyl peroxide, 2 kg of cellulose nanofibers, 1 kg of kaurene, 5 kg of flame retardant, 0.5 kg of toughening agent, and 1 kg of lubricant.

[0074] The specific steps of the method for preparing the insulating layer material of this embodiment are as follows:

[0075] S1: Preparation of cellulose nanofibers

[0076] (1) Add 50 g of Masson pine powder to 0.75 L of 0.5 mol / L sodium hydroxide aqueous solution, heat to 80 °C and stir for 8 h, filter, wash, freeze-dry at -50 °C for 8 h, grind to 500 mesh, take 10 g and mix with 1 L of 30% hydrogen peroxide solution, stir at 80 °C for 10 h, filter, wash, freeze-dry at -50 °C for 8 h to obtain cellulose;

[0077] (2) Add 10 g of cellulose to a mixed solution of 520 mL of 80% citric acid and 130 mL of 37% hydrochloric acid, heat to 140 °C, stir evenly, filter, wash, transfer the washed slurry to a homogenizer, homogenize 10 times at 150 MPa, and freeze-dry at -50 °C for 8 h to obtain cellulose nanofibers;

[0078] S2: Preparation of β-caryophyllene-maleic anhydride-polyethylene copolymer

[0079] 50 g of β-caryophyllene, 10 g of maleic anhydride, 10 g of polyethylene, 1 g of di-tert-butyl peroxide and 100 mL of cyclohexanone were stirred evenly, heated to 140° C. for reaction for 4 h under a nitrogen atmosphere, cooled to room temperature, and dichloromethane was added and stirred evenly to obtain a mixed solution, the mixed solution was poured into methanol, a precipitate was precipitated, filtered, washed, and dried to obtain a β-caryophyllene-maleic anhydride-polyethylene copolymer;

[0080] S3: Preparation of insulation layer materials

[0081] Polyethylene, ethylene-octene copolymer, β-caryophyllene-maleic anhydride-polyethylene copolymer and kaurene are put into an internal mixer, heated to 140°C and softened for 20 minutes, di-tert-butyl peroxyisopropylbenzene and di-tert-butyl peroxide are added into the internal mixer and kneaded for 10 minutes, and then cellulose nanofibers, flame retardant, toughening agent and lubricant are added, the temperature is raised to 130°C, and extrusion is performed to obtain an insulating layer material.

[0082] Comparative Example 1

[0083] In this comparative example, the effect of the amount of kaurene added on the properties of the insulating layer material was investigated.

[0084] The difference from Example 1 is the amount of kaurene added, and the rest is the same as Example 1, as shown in Table 1 for details.

[0085] Table 1 Amount of Kaurene added

[0086]

[0087] Comparative Example 2

[0088] In this comparative example, the effect of the amount of cellulose nanofiber added on the performance of the insulation layer material was investigated.

[0089] The difference from Example 1 is the amount of cellulose nanofiber added, and the rest is the same as Example 1, as shown in Table 2 for details.

[0090] Table 2 Addition amount of cellulose nanofibers

[0091]

[0092] Comparative Example 3

[0093] This comparative example examines the effects of the proportion and addition amount of the composite cross-linking agent on the properties of the insulating layer material.

[0094] The difference from Example 1 is the amount of the composite cross-linking agent added, and the rest is the same as Example 1, as shown in Table 3 for details.

[0095] Table 3 Addition amount of composite crosslinking agent

[0096]

[0097] Comparative Example 4

[0098] In this comparative example, the effect of β-caryophyllene-maleic anhydride-polyethylene copolymer on the properties of the insulation layer material was investigated.

[0099] The difference from Example 1 is that no β-caryophyllene-maleic anhydride-polyethylene copolymer is added in this comparative example, and the rest is the same as Example 1.

[0100] Performance Testing

[0101] Relevant performance tests were performed on Example 1 to Example 4 and Comparative Example 1 to Comparative Example 4 in accordance with GB / T 2951-2008. The test results are shown in Table 4.

[0102] Table 4 Test results

[0103]

[0104] By comparing Comparative Example 1 with Example 1, it can be seen that the addition of kaurene can enhance the resistivity of the cable insulation layer material and enhance the insulation performance of the cable under high voltage; at the addition amount of Comparative Example 1b, kaurene has little effect on resistivity enhancement; when the amount of kaurene added is too much, the resistivity decreases instead, which may be due to the excessive formation of agglomerates by the kaurene, resulting in local concentration of the electric field; at the same time, excessive kaurene tends to reduce the mechanical properties of the insulation layer material.

[0105] From the comparison between Comparative Example 2 and Example 1, it can be seen that the addition of cellulose nanofibers can form a dense network structure with polyethylene during the cross-linking process of polyethylene, enhance the insulation performance of the material, and at the same time can effectively share and transfer stress and improve the mechanical properties of the material.

[0106] It can be seen from the comparison between Comparative Example 3 and Example 1 that di-tert-butyl peroxyisopropylbenzene and di-tert-butyl peroxide can play a synergistic role in the crosslinking process and jointly promote the crosslinking reaction. When the amount of the composite crosslinking agent added is too much, it is easy to cause the insulation resistance of the insulating layer material to decrease, affecting the insulation performance, which may be caused by the increase of impurities in the crosslinking process.

[0107] By comparing Comparative Example 4 with Example 1, it can be seen that the addition of β-caryophyllene-maleic anhydride-polyethylene copolymer can improve the tensile strength of the cable material; the β-caryophyllene-maleic anhydride-polyethylene copolymer is cross-linked with polyethylene, and the β-caryophyllene-maleic anhydride-polyethylene copolymer has a certain spatial structure. The double bond structure and aromatic groups contained in the copolymer can interact with the polyethylene chain, thereby enhancing the tensile strength and thermal stability of the insulating layer material, reducing the degradation of the insulating layer material at high temperature, and helping to delay the thermal aging process of the cable.

[0108] The above is an exemplary description of the present invention. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or equivalent replacement that can be done by other technicians in this field without expending creative labor falls within the protection scope of the present invention.

Claims

1. High voltage cable for new energy vehicles, characterized in that: It comprises a conductor and an insulating layer; the insulating layer material is made of the following raw materials in parts by weight: 40-50 parts of polyethylene, 10-15 parts of ethylene-octene copolymer, 5-10 parts of β-caryophyllene-maleic anhydride-polyethylene copolymer, 1-4 parts of a composite crosslinking agent, 2-3 parts of cellulose nanofibers, 1-2 parts of kaurene, 5-10 parts of a flame retardant, 0.5-1 parts of a toughening agent, and 0.5-1 parts of a lubricant; The composite cross-linking agent is prepared by mixing di-tert-butyl peroxyisopropylbenzene and di-tert-butyl peroxide in a mass ratio of (3-4):

1.

2. The high-voltage cable for new energy vehicles according to claim 1, characterized in that: The preparation method of the cellulose nanofibers comprises the following steps: (1) treating Masson pine powder with alkali, mixing it evenly with a hydrogen peroxide solution, filtering, washing, and drying to obtain cellulose; (2) The cellulose and the composite acid are mixed evenly, filtered, washed, the washed slurry is homogenized, and dried to obtain cellulose nanofibers.

3. The high-voltage cable for new energy vehicles according to claim 2, characterized in that: In the step (1), the alkali treatment is to react the Masson pine powder with a sodium hydroxide aqueous solution at 60-80° C. for 4-8 hours; The ratio of Masson pine powder to sodium hydroxide aqueous solution is 1g:15-20mL, and the concentration of sodium hydroxide aqueous solution is 0.2-0.5mol / L.

4. The high-voltage cable for new energy vehicles according to claim 2, characterized in that: In the step (2), the ratio of cellulose to composite acid is 1 g:30-80 mL; the mixing temperature is 70-100° C.; The composite acid is prepared by mixing citric acid and hydrochloric acid in a mass ratio of (2-4):

1.

5. The high-voltage cable for new energy vehicles according to claim 1, characterized in that: The preparation method of the β-caryophyllene-maleic anhydride-polyethylene copolymer comprises the following steps: β-caryophyllene, maleic anhydride, polyethylene, di-tert-butyl peroxide and cyclohexanone are mixed uniformly, heated under a nitrogen atmosphere for reaction, cooled to room temperature, and dichloromethane is added and mixed uniformly to obtain a mixed solution, and the mixed solution is poured into methanol to precipitate, filtered, washed, and dried to obtain a β-caryophyllene-maleic anhydride-polyethylene copolymer; The mass ratio of the β-caryophyllene, maleic anhydride and polyethylene is (2-5):1:

1.

6. The high-voltage cable for new energy vehicles according to claim 1, characterized in that: The method for preparing the insulating layer material comprises the following steps: Put polyethylene, ethylene-octene copolymer and kaurene into an internal mixer, heat up to soften, add the composite cross-linking agent into the internal mixer and mix for 5-10 minutes, then add cellulose nanofiber, flame retardant, toughening agent and lubricant, heat up to 130-150℃, extrude and shape to obtain insulation layer material.

7. The high-voltage cable for new energy vehicles according to claim 6, characterized in that: The temperature for the heating and softening is 120-140° C., and the time for the heating and softening is 10-20 minutes.

8. The high-voltage cable for new energy vehicles according to claim 1, characterized in that: The conductor is formed by twisting a plurality of metal cores; an inner semi-conductive layer, an insulating layer, an outer semi-conductive layer, a shielding layer and an outer sheath are sequentially coated along the axial direction of the conductor itself.

9. The high-voltage cable for new energy vehicles according to claim 8, characterized in that: The metal core is a copper core.

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