A semiconductive shielding material for an ultrahigh voltage direct current cable and a preparation method and application thereof

Abstract

This invention discloses a semiconductive shielding material for ultra-high voltage DC cables, its preparation method, and its application. The material comprises 60-80 parts of a matrix resin, 5-15 parts of an MXene / graphene composite material, 10-30 parts of conductive carbon black, 0.5-10 parts of a lubricant, 0.1-2 parts of an antioxidant, and 0.1-5 parts of a crosslinking agent. In this invention, a MXene / graphene composite material with a designable interlayer structure is prepared by plasma exfoliation. Plasma breaks the C-O bonds in graphene oxide, reducing it to reduced graphene oxide (rGO). Due to the expansion caused by the breaking of C-O bonds, MXene is exfoliated to obtain an MXene / graphene / MXene "sandwich" structure. The two materials overlap to form a complete conductive network. This method is simple to prepare and effectively reduces agglomeration while increasing the specific surface area of ​​the composite material. No other organic or non-conductive molecules are introduced during the preparation process, thus improving the electrochemical performance of the material. The addition of this composite material can effectively uniformize the electric field, rapidly dissipate charges during power transmission and de-energization, improve power transmission safety, and at the same time reduce the amount of carbon black used, thereby improving the mechanical and processing properties of the semiconductive shielding material.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of cross-linked polyethylene cable materials, and particularly relates to a semi-conductive shielding material for an ultra-high voltage direct current cable and a preparation method and application thereof. BACKGROUND

[0002] The key to ultra-high voltage direct current cable transmission lies in solving space charge accumulation, so a semi-conductive shielding material is needed to quickly discharge the charge, homogenize the electric field, improve the safety of power transmission, and improve the apparent defects of the cable.

[0003] As a new type of material, MXene has good electrical conductivity and electrochemical performance, so it has wide application prospects in the field of cables and the like. Graphene, as another excellent carbon-based material, has high electrical conductivity and thermal stability, and can improve the structure and electrochemical performance of MXene, so it has become a common method for preparing MXene composites.

[0004] The prior art document CN118335951A discloses a MXene / graphene composite and a preparation method and application thereof. The specific preparation method is to configure a MXene / oxidized graphene mixed aqueous solution, then add a reducing agent to reduce the oxidized graphene, obtain a MXene / graphene aqueous solution, and filter, wash and dry to obtain a MXene / graphene composite. However, the composite material prepared by this method cannot design the interlayer structure of the material, the specific surface area of the prepared composite material is small, and the electrical conductivity of the material is poor due to the introduction of other organic molecules and non-conductive molecules on the surface of MXene during the preparation process.

[0005] The prior art document CN113692211A discloses a preparation method of a MXene-rGO composite film. The method is to mix an oxidized graphene suspension and a MXene simple body solution, then vacuum filter to form a film, and place it in a quartz glass piece for high-temperature annealing to obtain a composite film. However, the composite material prepared by this preparation method is prone to agglomeration due to the structure. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a kind of semi-conductive shielding material for ultra-high voltage DC cable and its preparation method and application.For the technical problems of MXene / graphene composite material preparation difficulty, poor interlayer structure, easy to agglomerate and existing carbon black shielding material carbon black component many and resulting apparent defects, the present application prepares MXene / graphene composite material with designable interlayer structure by plasma stripping, plasma destroys C-O bond in graphene oxide and reduces it to reduced graphene oxide (rGO), MXene is stripped due to the expansion of C-O bond and obtains MXene / graphene / MXene " sandwich " type sandwich structure, and the two materials are overlapped to form a perfect conductive network.The method is simple, and effectively reduces the agglomeration while increasing the specific surface area of the composite material, without introducing other organic molecules and non-conductive molecules during preparation, improving the electrochemical performance of the material.The addition of the composite material can effectively uniform the electric field, quickly discharge the charge in the instant of power transmission and power off, improve the safety of power transmission, reduce the amount of carbon black used, and improve the mechanical properties and processing performance of the semi-conductive shielding material.

[0007] To achieve the above purpose, the technical solutions adopted by the present application are as follows:

[0008] A kind of semi-conductive shielding material for ultra-high voltage DC cable, by weight, it includes the following components: matrix resin 60-80 parts, MXene / graphene composite material 5-15 parts, conductive carbon black 10-30 parts, lubricant 0.5-10 parts, antioxidant 0.1-2 parts, crosslinking agent 0.1-5 parts.

[0009] The MXene / graphene composite material is prepared by the following steps:

[0010] S1. Oxidized graphene powder is dissolved in anhydrous ethanol solution to obtain an oxidized graphene colloidal solution;

[0011] S2. MXene powder and oxidized graphene colloidal solution are added to deionized water, then fully mixed after stirring, to obtain an oxidized graphene / MXene mixture;

[0012] S3. The oxidized graphene / MXene mixture is placed in a plasma reactor, and CH4 is used to remove the residual air in the tube by multiple vacuum extractions; after adjusting the outlet vacuum valve to maintain a certain CH4 flow and pressure, gradually increasing radio frequency power is introduced to generate plasma.

[0013] Preferably, the weight ratio of the oxidized graphene powder to the ethanol solution in S1 is 1:50-80; further preferably, it is 1:60-70.

[0014] Preferably, the weight ratio of the graphene oxide colloidal solution and the MXene powder in S2 is 1:10-30, and further preferably 1:15-25.

[0015] Preferably, the stirring speed in S2 is 8000-16000 rpm, and further preferably 11000-13000 rpm.

[0016] Preferably, the stirring time in S2 is 2-5 min, and further preferably 3-4 min.

[0017] Preferably, the CH4 gas flow rate in S3 is 50-150 sccm, and further preferably 80-120 sccm.

[0018] Preferably, the CH4 gas pressure in S3 is 2-4 Torr, and further preferably 2.5-3.5 Torr.

[0019] Preferably, the radio frequency power in S3 is gradually increased from 25 W to 75 W.

[0020] Preferably, the radio frequency processing time in S3 is 20-50 min, and further preferably 30-40 min, and preferably, the radio frequency power in S3 is gradually increased from 25 W to 75 W at a uniform speed within 20-50 min.

[0021] The base resin is selected from one or more of ethylene-vinyl acetate resin, ethylene-butyl acrylate resin or ethylene-ethyl acrylate resin, and preferably ethylene-butyl acrylate resin and / or ethylene-ethyl acrylate resin.

[0022] Preferably, the molar content of the vinyl acetate structural unit in the ethylene-vinyl acetate resin is 17-30% (for example, it can be 18%, 20%, 22%, 24%, 26%, 28%, etc.); the molar content of the butyl acrylate structural unit in the ethylene-butyl acrylate resin is 15-25% (for example, it can be 16%, 18%, 20%, 22%, 24%, etc.), and the molar content of the ethyl acrylate structural unit in the ethylene-ethyl acrylate resin is 15-25% (for example, it can be 16%, 18%, 20%, 22%, 24%, etc.).

[0023] Preferably, the conductive carbon black comprises furnace black or acetylene carbon black, and further preferably acetylene carbon black.

[0024] Preferably, the particle size of the acetylene carbon black is 20-40 nm, for example, it can be 25 nm, 30 nm, 35 nm, etc.

[0025] Preferably, the acetylene black has an oil absorption value greater than 210cc / 100g, such as 220cc / 100g, 230cc / 100g, 240cc / 100g, 250cc / 100g, or 260cc / 100g, and an iodine absorption value greater than 150g / kg, such as 160g / kg, 170g / kg, 180g / kg, 190g / kg, or 200g / kg.

[0026] Preferably, the crosslinking agent includes dicumyl peroxide and / or bis-tert-butyl peroxide, more preferably bis-tert-butyl peroxide.

[0027] Preferably, the cable shielding material further includes 0.5 to 10 parts of lubricant by weight, for example, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, etc.

[0028] Preferably, the lubricant is one or more of zinc stearate, pentaerythritol, and polyethylene wax, and more preferably polyethylene wax;

[0029] Preferably, the cable shielding material further includes 0.1 to 2 parts of antioxidant, for example, 0.5 parts, 1 part, 1.5 parts, 2 parts, etc.

[0030] Preferably, the antioxidant is one or more of antioxidant 1010 and antioxidant 300, and more preferably antioxidant 1010;

[0031] Secondly, the present invention provides a method for preparing cable shielding material, the method comprising the following steps:

[0032] The matrix resin, conductive carbon black, MXene / graphene composite material, antioxidant, and lubricant are mixed and extruded to obtain a resin composite material. The resin composite material is then post-absorbed with a crosslinking agent to obtain the cable shielding material.

[0033] Preferably, the mixing is carried out in a mixer.

[0034] Preferably, the temperature of the feeding section of the mixer is 80-90°C, for example, 82°C, 84°C, 86°C, 88°C, etc.

[0035] Preferably, the temperature of the melting section of the mixer is 120-130°C; for example, it can be 122°C, 124°C, 126°C, 128°C, etc.; preferably, the temperature of the plasticizing section of the mixer is 140-150°C; for example, it can be 142°C, 144°C, 146°C, 148°C, etc.; preferably, the temperature of the extrusion section of the mixer is 150-160°C; for example, it can be 152°C, 154°C, 156°C, 158°C, etc.; and the extrusion process further includes a granulation step.

[0036] In this invention, the granulation is carried out in water.

[0037] Preferably, the granulation temperature is 40-50°C, for example, 42°C, 44°C, 46°C, 48°C, etc.

[0038] Preferably, the post-absorption process involves atomizing the crosslinking agent and then performing a post-absorption process with the resin composite material.

[0039] Preferably, the temperature of the post-absorption is 60-80°C, for example, it can be 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, etc.

[0040] Preferably, the post-absorption time is 20 to 30 hours, for example, 22 hours, 24 hours, 26 hours, 28 hours, etc.

[0041] Thirdly, the present invention provides an ultra-high voltage cable material, the ultra-high voltage cable material comprising the cable shielding material according to the first aspect.

[0042] In this invention, ultra-high voltage refers to voltages above 220kV.

[0043] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] The cable shielding material provided by this invention utilizes plasma exfoliation to prepare an MXene / graphene composite material with a designable interlayer structure. Plasma breaks the CO bonds in graphene oxide, reducing it to reduced graphene oxide (rGO). The expansion caused by the broken CO bonds exfoliates MXene, resulting in an MXene / graphene / MXene "sandwich" structure. The two materials interlock to form a complete conductive network. This method is simple to prepare and effectively reduces agglomeration while increasing the specific surface area of ​​the composite material. No other organic or non-conductive molecules are introduced during the preparation process, improving the electrochemical performance of the material. The addition of this composite material effectively homogenizes the electric field, rapidly dissipating charge during power transmission and de-energization, improving power transmission safety. Simultaneously, it reduces the amount of carbon black used and enhances the mechanical and processing properties of the semi-conductive shielding material. Detailed Implementation

[0046] The present invention will be further described below with reference to the embodiments, but the scope of protection of the present invention is not limited to the embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0047] The materials and instruments used in this invention are as follows:

[0048] Reciprocating mixer: Swiss BUSS AG, model: MX-30.

[0049] High-speed mixer: German VMA, model: LC220-12.

[0050] RF generator: Shanghai Xiangshu Oumao Electromechanical Equipment Co., Ltd., model RFR601 13.56MHz.

[0051] Graphene oxide: Suzhou CarbonFeng Technology Co., Ltd., analytical grade.

[0052] Anhydrous ethanol: Chengdu Kelong Chemical Co., Ltd., analytical grade.

[0053] Ethylene-butyl acrylate resin (EBA): Dow 3427, melt index 4 g / 10 min (190℃, 2.16 kg).

[0054] Carbon black: Cabot, VXC500.

[0055] Polyethylene wax: EUROCERAS, CERALENE 691.

[0056] Antioxidant: Ciba Specialty Chemicals, Switzerland, Antioxidant 300.

[0057] Crosslinking agent: bis(tert-butylperoxyisopropylbenzene) (BIPB), 99% purity, Akema.

[0058] Preparation Example 1

[0059] An MXene / graphene composite material is prepared by the following steps:

[0060] S1. Take 10 mg of graphene oxide powder, disperse it in 800 ml of anhydrous ethanol solution, and sonicate for 1 h to prepare a graphene oxide colloidal solution.

[0061] S2. Take 300 mg of MXene powder and 20 ml of graphene oxide colloidal solution and add them to deionized water. Then stir at 12000 rpm for 3 min to mix and obtain a graphene oxide / MXene mixture.

[0062] S3. Take 50 ml of graphene oxide / MXene mixture and put it into the plasma reactor. Use CH4 to evacuate the tube multiple times to remove residual air. Then adjust the outlet vacuum valve to keep the CH4 flow rate in the reactor at 100 sccm and the pressure at 3 Tor. Finally, introduce radio frequency power from 25 W to 75 W to generate plasma and perform radio frequency treatment for 35 min.

[0063] Thus, MXene / graphene composite materials were prepared.

[0064] Preparation Example 2

[0065] An MXene / graphene composite material is prepared by the following steps:

[0066] S1. Take 10 mg of graphene oxide powder, disperse it in 750 ml of anhydrous ethanol solution, and sonicate for 1 h to prepare a graphene oxide colloidal solution.

[0067] S2. Take 240 mg of MXene powder and 20 ml of graphene oxide colloidal solution and add them to deionized water. Then stir at 12000 rpm for 3 min to mix and obtain a graphene oxide / MXene mixture.

[0068] S3. Take 50 ml of graphene oxide / MXene mixture and put it into the plasma reactor. Use CH4 to evacuate the tube multiple times to remove residual air. Then adjust the outlet vacuum valve to keep the CH4 flow rate in the reactor at 80 sccm and the pressure at 2.5 Tor. Finally, introduce radio frequency power from 25 W to 75 W to generate plasma and perform radio frequency treatment for 30 min.

[0069] Preparation Example 3

[0070] An MXene / graphene composite material, which differs from Preparation Example 1 only in that the CH4 flow rate in the reactor described in S3 is 120 sccm, the pressure is 3.5 Tor, and the radio frequency treatment time is 40 min.

[0071] Example 1

[0072] This embodiment provides a cable shielding material, which, by weight, comprises 60 parts of ethylene-butyl acrylate resin, 30 parts of conductive carbon black, 5 parts of MXene / graphene composite material (Preparation Example 1), 1.5 parts of antioxidant 300, 2 parts of polyethylene wax, and 1.5 parts of di-tert-butyl peroxide diisopropylbenzene.

[0073] This embodiment provides a method for preparing cable shielding material, including the following steps:

[0074] (1) EBA resin, conductive carbon black, MXene / graphene composite material, antioxidant 300 and polyethylene wax are added to a reciprocating mixer for mixing, filtering, extrusion, underwater granulation and drying to obtain resin composite material; the temperature of the mixing feeding section is 80℃, the temperature of the melting section is 130℃, the temperature of the plasticizing section is 150℃, the temperature of the extrusion section is 160℃, and the screw speed is 300rpm; in the extrusion granulation, the die head temperature is 160℃, the melt pressure is 7~7.5MPa, and the underwater pelletizing temperature is 45℃.

[0075] (2) The di-tert-butyl peroxide diisopropylbenzene crosslinking agent is atomized and then introduced into a shaking tank for post-absorption with the granules obtained in step (1). The mixture is kept at 70°C for 24 hours to ensure complete absorption of the crosslinking agent. The material is continuously sampled for impurity testing, and finally packaged to obtain the cable shielding material.

[0076] Example 2

[0077] This embodiment provides a cable shielding material, which, by weight, comprises 65 parts of ethylene-butyl acrylate resin, 20 parts of conductive carbon black, 10 parts of MXene / graphene composite material (Preparation Example 1), 1.5 parts of antioxidant 300, 1.2 parts of polyethylene wax, and 2.3 parts of di-tert-butyl peroxide diisopropylbenzene.

[0078] This embodiment provides a method for preparing cable shielding material, including the following steps:

[0079] (1) EBA resin, conductive carbon black, MXene / graphene composite material, antioxidant 300 and polyethylene wax are added to a reciprocating mixer for mixing, filtering, extrusion, underwater granulation and drying to obtain resin composite material; the temperature of the mixing feeding section is 75℃, the temperature of the melting section is 140℃, the temperature of the plasticizing section is 155℃, the temperature of the extrusion section is 165℃, and the screw speed is 320rpm; in the extrusion granulation, the die head temperature is 160℃, the melt pressure is 7~7.5MPa, and the underwater pelletizing temperature is 40℃.

[0080] (2) The di-tert-butyl peroxide diisopropylbenzene crosslinking agent is atomized and then introduced into a shaking tank for post-absorption with the granules obtained in step (1). The mixture is kept at 70°C for 24 hours to ensure complete absorption of the crosslinking agent. The material is continuously sampled for impurity testing, and finally packaged to obtain the cable shielding material.

[0081] Example 3

[0082] This embodiment provides a cable shielding material, which, by weight, comprises 70 parts of ethylene-butyl acrylate resin, 10 parts of conductive carbon black, 15 parts of MXene / graphene composite material (Preparation Example 1), 1.5 parts of antioxidant 300, 0.5 parts of polyethylene wax, and 2 parts of di-tert-butyl peroxide diisopropylbenzene.

[0083] This embodiment provides a method for preparing cable shielding material, including the following steps:

[0084] (1) EBA resin, conductive carbon black, MXene / graphene composite material, antioxidant 300 and polyethylene wax are added to a reciprocating mixer for mixing, filtering, extrusion, underwater granulation and drying to obtain resin composite material; the temperature of the mixing feeding section is 85℃, the temperature of the melting section is 130℃, the temperature of the plasticizing section is 150℃, the temperature of the extrusion section is 165℃, and the screw speed is 300rpm; in the extrusion granulation, the die head temperature is 160℃, the melt pressure is 7~7.5MPa, and the underwater pelletizing temperature is 50℃.

[0085] (2) The di-tert-butyl peroxide diisopropylbenzene crosslinking agent is atomized and then introduced into a shaking tank for post-absorption with the granules obtained in step (1). The mixture is kept at 70°C for 24 hours to ensure complete absorption of the crosslinking agent. The material is continuously sampled for impurity testing, and finally packaged to obtain the cable shielding material.

[0086] Example 4

[0087] This embodiment provides a cable shielding material, which differs from Embodiment 1 only in that the MXene / graphene composite material is the MXene / graphene composite material provided in Preparation Example 2, while the other raw materials, dosages, and preparation methods are the same as in Embodiment 1.

[0088] Example 5

[0089] This embodiment provides a cable shielding material, which differs from Example 1 only in that the MXene / graphene composite material is the MXene / graphene composite material provided in Preparation Example 3, while the other raw materials, dosages, and preparation methods are the same as in Example 1.

[0090] Comparative Example 1

[0091] This comparative example provides a cable shielding material, which differs from Example 1 only in that the MXene / graphene composite material is replaced with graphene and MXene, and the total weight of graphene and MXene is 5 parts, with a mass ratio of 1:3. Other raw materials, dosages, and preparation methods are the same as in Example 1.

[0092] Comparative Example 2

[0093] This comparative example provides a cable shielding material, which differs from Example 1 only in that the cable shielding material includes 5 parts of graphene and does not contain MXene. The other raw materials, amounts, and preparation methods are the same as in Example 1.

[0094] Comparative Example 3

[0095] This comparative example provides a cable shielding material, which, by weight, comprises 68 parts of ethylene-butyl acrylate resin, 28 parts of conductive carbon black, 1 part of antioxidant 300, 1 part of polyethylene wax, and 2 parts of di-tert-butyl peroxide diisopropylbenzene.

[0096] This comparative example provides a method for preparing cable shielding material, including the following steps:

[0097] (1) EBA resin, conductive carbon black, antioxidant 300 and polyethylene wax are added to a reciprocating mixer for mixing, filtering, extrusion, underwater granulation and drying to obtain a resin composite material; the temperature of the mixing and feeding section is 80℃, the temperature of the melting section is 130℃, the temperature of the plasticizing section is 140℃, the temperature of the extrusion section is 160℃, and the screw speed is 300rpm; in the extrusion granulation, the die head temperature is 160℃, the melt pressure is 7~7.5MPa, and the underwater pelletizing temperature is 45℃.

[0098] (2) The di-tert-butyl peroxide diisopropylbenzene crosslinking agent is atomized and then introduced into a shaking tank for post-absorption with the granules obtained in step (1). The mixture is kept at 70°C for 24 hours to ensure complete absorption of the crosslinking agent. The material is continuously sampled for impurity testing, and finally packaged to obtain the cable shielding material.

[0099] Performance testing

[0100] The sample preparation method adopts the particle molding method, and is carried out in accordance with the provisions of 6.2.1 of JB / T 10738-2007. The sample should be flat, smooth, uniform in thickness, and free of air bubbles. The thickness of the sample should meet the requirements of each test item. The test standard refers to Q / GDW11883.2—2018; the detailed test method is as follows:

[0101] (1) Density test: The test method shall be carried out in accordance with GB / T 1033.1; a square test piece with a thickness of 2.0±0.1mm and a side length of 20-25mm shall be used.

[0102] (2) Mechanical properties: The test method was carried out in accordance with ISO 527, ISO 178 and ISO 180 standards, using an INSTRON 5966 tensile tester.

[0103] (3) Air heat aging performance: heat aging at 135℃ for 7 days, in accordance with the provisions of GB / T2951.12; test the mechanical properties of the aged product.

[0104] (4) Heat extension: Performed in accordance with GB / T 2951.5, and the sample preparation shall be performed in accordance with GB / T 1040.2.

[0105] (5) Volume resistivity: The volume resistivity at 23℃ shall be determined in accordance with GB / T 3048.3, and the sample shall be acclimated in an environment with a temperature of 23±3℃ and a relative humidity of 50±5% for no less than 24 hours. The volume resistivity at 90℃ shall be determined in accordance with Appendix A of GB / T 3048.3. The volume resistivity at 90℃ after 7 days of heat aging at 135℃ shall be determined in accordance with Appendix A of GB / T 3048.3, and the heat aging shall be performed in accordance with GB / T2951.12.

[0106] (6) Smoothness: As specified in Appendix A of Q / GDW 11883.2-2018 standard, the resolution of the protrusion height of the detector should be better than 25μm. Sampling and testing standards: Class 1000 cleanroom; record the size and number of surface protrusions.

[0107] The specific test results are shown in Table 1:

[0108]

[0109] As shown in the table above, the cable shielding material provided by this invention, by incorporating MXene / graphene composite material, reduces the amount of conductive carbon black added, achieves uniform dispersion of conductive filler, and reduces the generation of impurities and air gaps, thereby avoiding electric field concentration and breakdown caused by impurities and air gaps. Furthermore, it gives the cable excellent conductivity, with minimal change in resistivity with temperature; a smooth surface, and excellent mechanical and processing properties, fully meeting the mechanical performance requirements of ultra-high voltage cable materials, and retaining excellent mechanical and conductivity even after aging. As shown in Examples 1-5, the cable shielding material has a density of 1.11-1.13 g / cm³, a cable tensile strength of 19.8-22.8 MPa, and an elongation at break of 210-215%, and retains excellent mechanical and conductivity even after aging.

[0110] The tensile strength change rate was 12.8%–14.2%, the elongation at break change rate was -12.7%–-10.5%, and the load elongation was 25%.

[0111] ~29%, permanent deformation rate is 0, volume resistivity is low, only 6.1~8.5Ω·cm at 23℃, surface is smooth, and the number of bumps and depressions of 50-75μm and above is 0~1 / m2.

[0112] As can be seen from the comparison between the examples and the comparative examples, the volume resistivity of the cable shielding material increases when MXene is not present or when graphene and MXene are mixed and added. Furthermore, the comparative examples 2 and 3 have poor processing performance, resulting in poor mechanical properties and a large number of surface protrusions.

[0113] In summary, the cable shielding material provided by this invention is a MXene / graphene composite material with a designable interlayer structure prepared by plasma exfoliation. The addition of this graphene / MXene composite material can effectively uniformize the electric field and quickly dissipate charges at the moment of power transmission and power failure, thereby improving power transmission safety. At the same time, it can reduce the amount of carbon black used and improve the mechanical and processing properties of the semiconductive shielding material, making it particularly suitable for the preparation of ultra-smooth ultra-high voltage cables.

[0114] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A semiconductive shielding material for ultra-high voltage DC cables, comprising the following components by weight: 60-80 parts of matrix resin, 5-15 parts of MXene / graphene composite material, 10-30 parts of conductive carbon black, 0.5-10 parts of lubricant, 0.1-2 parts of antioxidant, and 0.1-5 parts of crosslinking agent.

2. The semiconductive shielding material for ultra-high voltage DC cables as described in claim 1, characterized in that, The MXene / graphene composite material is prepared through the following steps: S1. Dissolve graphene oxide powder in anhydrous ethanol solution to obtain graphene oxide colloidal solution; S2. Take MXene powder and graphene oxide colloidal solution and add them to deionized water. Then stir and mix thoroughly to obtain a graphene oxide / MXene mixture. S3. Place the graphene oxide / MXene mixture into the plasma reactor, and use CH4 to repeatedly evacuate and remove residual air from the tube; after adjusting the outlet vacuum valve to maintain a certain CH4 flow rate and pressure, gradually increase the radio frequency power to generate plasma.

3. The semiconductive shielding material for ultra-high voltage DC cables as described in claim 2, characterized in that, The weight ratio of graphene oxide powder to ethanol solution in S1 is 1:50-80; more preferably 1:60-70; and / or, the weight ratio of graphene oxide colloidal solution to MXene powder in S2 is 1:10-30, more preferably 1:15-25; and / or, the stirring speed in S2 is 8000-16000 rpm, more preferably 11000-13000 rpm; and / or, the stirring time in S2 is 2-5 min, more preferably 3-4 min.

4. The semiconductive shielding material for ultra-high voltage DC cables as described in claim 2 or 3, characterized in that, The CH4 gas flow rate in S3 is 50–150 sccm, more preferably 80–120 sccm; and / or, the CH4 gas pressure in S3 is 2–4 Torr, more preferably 2.5–3.5 Torr; and / or, the RF power in S3 gradually increases from 25W to 75W; and / or, the RF processing time in S3 is 20–50 min, more preferably 30–40 min.

5. The ultra-high voltage DC cable semi-conductive shielding material as described in any one of claims 1-4, characterized in that, The matrix resin is selected from one or more of ethylene-vinyl acetate resin, ethylene-butyl acrylate resin, or ethylene-ethyl acrylate resin, preferably ethylene-butyl acrylate resin and / or ethylene-ethyl acrylate resin; and / or, the molar content of vinyl acetate structural units in the ethylene-vinyl acetate resin is 17-30%; the molar content of butyl acrylate structural units in the ethylene-butyl acrylate resin is 15-25%; the molar content of ethyl acrylate structural units in the ethylene-ethyl acrylate resin is 15-25%; and / or, the conductive carbon black includes furnace black or acetylene black, more preferably acetylene black; and / or, the crosslinking agent includes dicumyl peroxide and / or bis-tert-butyldiisopropyl peroxide, preferably bis-tert-butyldiisopropyl peroxide.

6. The method for preparing the semiconductive shielding material for ultra-high voltage DC cables according to any one of claims 1-5, characterized in that, The method includes the following steps: The matrix resin, conductive carbon black, MXene / graphene composite material, antioxidant, and lubricant are mixed and extruded to obtain a resin composite material. The resin composite material is then post-absorbed with a crosslinking agent to obtain the cable shielding material.

7. The preparation method according to claim 6, characterized in that, The temperature of the feeding section of the mixer is 80-90°C; and / or the temperature of the melting section of the mixer is 120-130°C; and / or the temperature of the plasticizing section of the mixer is 140-150°C; and / or the temperature of the extrusion section of the mixer is 150-160°C.

8. The preparation method according to claim 6 or 7, characterized in that, The granulation temperature is 40–50°C; and / or the post-absorption temperature is 60–80°C; and / or the post-absorption time is 20–30 h.

9. An ultra-high voltage cable material, wherein the ultra-high voltage cable material comprises the ultra-high voltage DC cable semi-conductive shielding material as described in any one of claims 1-5 or the ultra-high voltage DC cable semi-conductive shielding material prepared by the preparation method as described in any one of claims 6-8.

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