Cable buffer layer semiconductive material and preparation method thereof

Abstract

The invention discloses a cable buffer layer semi-conductive material and a preparation method thereof, and belongs to the technical field of high-voltage cable materials. The material is composed of a polymer I (a monomer A, octafluoroamyl methacrylate, 4-vinyl catechol and 4-n-octyl styrene are polymerized according to a specific molar ratio, and the monomer A is prepared from DOPO, APBIA and methacrylic acid) and carbon black capable of adsorbing metal ions. The material forms reversible coordinate bonds with iron ions on the surface of carbon black through catechol groups to realize self-repairing, has strong hydrophobicity, excellent flame retardance, stable conductivity and high interface adhesion, can solve the problems of damping, poor contact, ablation damage and the like of a buffer layer of a high-voltage cable, prolongs the service life of the cable, guarantees power supply safety, and is suitable for popularization and application. And the device is suitable for high-voltage cable buffer layers of 110kV and above.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-voltage cable materials, in particular to a semi-conductive material for cable buffer layer and a preparation method thereof. BACKGROUND

[0002] With the continuous growth of urban power load, the construction of high-voltage transmission and distribution lines has entered a rapid development stage, and high-voltage cables of 110kV and above voltage grade have been widely used in power transmission systems. High-voltage cables usually adopt a corrugated aluminum sheath structure, which bears the core functions of carrying short-circuit current and protecting the cable body. The buffer layer between the cable conductor shielding layer and the insulation layer is a key structural layer to ensure the stable operation of the cable.

[0003] The core functions of the buffer layer include three aspects: first, absorbing and dispersing the mechanical stress generated by the cable during bending, thermal expansion and contraction, to avoid damage to the insulation layer due to stress; second, blocking water penetration along the longitudinal direction of the cable through water-resistant materials to protect the internal conductor and insulation structure; third, filling the uneven surface of the conductor after twisting to form a smooth cylindrical structure to ensure uniform electric field distribution. In the prior art, the conventional buffer layer is usually made of a sponge-like strip-shaped material made of semi-conductive polyester non-woven fabric, and the water-resistant buffer layer is composed of semi-conductive non-woven fabric and semi-conductive fluffy cotton, with water-resistant powder filled in the middle to achieve moisture-proof function.

[0004] However, the existing buffer layer has many technical defects in actual operation, which seriously affects the service life and power supply safety of high-voltage cables. On the one hand, poor local contact often occurs between the buffer layer and the corrugated aluminum sheath, resulting in increased surface contact resistance and further causing local heating; on the other hand, the existing buffer layer material is prone to moisture, and the moisture-absorbed material will react with the aluminum sheath, further increasing the resistance and reducing the conductivity, exacerbating the poor contact problem. Under the long-term action of heat, electricity, and mechanical factors, the buffer layer will gradually appear ablation, defects, and damage, and the above-mentioned poor contact, moisture-induced white spots, or large gap between the buffer layer and the aluminum sheath will cause electric field distortion, and when the field strength is greater than the air breakdown voltage, local discharge will occur, continuously ablate the buffer layer until the insulation shielding layer, and eventually cause the cable body to break down.

[0005] In the past decade of engineering practice, the buffer layer and the insulation shielding surface have been found to have "ablation" phenomenon due to overheating during the migration, modification, and dissection of the cable body, and some cases have caused cable breakdown. This problem has attracted great attention in the industry. More importantly, this type of defect is difficult to appear in a short period of time during normal operation of the cable, and the mechanism is complex, and the existing technology cannot achieve self-repair of the defect from the material level, but only relies on later maintenance or replacement, which not only increases the operation and maintenance cost, but also poses a risk to power supply safety.

[0006] The current high-voltage cable market is highly competitive. In order to meet the market's higher demands for cable reliability, service life and power supply safety, and to enhance the core competitiveness of enterprises, it is of great practical significance to develop a cable buffer layer semiconductive material that can solve the above defects and has self-healing function. This is to ensure the long-term stable operation of high-voltage cables and reduce the failure rate. Summary of the Invention

[0007] In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a cable buffer layer semiconductive material and its preparation method. The buffer layer semiconductive material has the technical effects of flexibility, hydrophobicity, fire resistance, bending resistance and self-healing.

[0008] In a first aspect, the present invention provides a semiconductive material for a cable buffer layer, characterized in that, by weight, it comprises the following components: 100 parts of polymer I and 10-18 parts of carbon black adsorbing metal ions; wherein polymer I is obtained by polymerization of monomer A, monomer B: octafluoropentyl methacrylate, monomer C: 4-vinylcatechol, and monomer D: 4-n-octylstyrene, wherein the molar ratio of monomers A, B, C, and D is (15-20):(30-40):(25-30):(40-45); monomer A has the following structural formula: .

[0009] Monomer A was prepared from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), 2-(4-aminophenyl)-5-aminobenzimidazole (APBIA), and methacrylic acid. The specific preparation method of monomer A is as follows: A1: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and 2-(4-aminophenyl)-5-aminobenzimidazole (APBIA) were dissolved in anhydrous N-methylpyrrolidone (NMP) and reacted at 120±5℃ for 4-8 h under a nitrogen atmosphere. After purification, the intermediate DOPO-APBIA was obtained.

[0010] A2: Dissolve methacrylic acid in N-methylpyrrolidone (NMP), add NHS / DCC, stir for 1-3 h to activate the carboxyl group, then add to the NMP solution of intermediate DOPO-APBIA, stir for 3-5 h; purify to obtain monomer A.

[0011] The molar ratio of DOPO, APBIA, and methacrylic acid is 1:(1.05-1.2):(1.05-1.1).

[0012] The preparation method of polymer I is as follows: S1: Add monomers A, B, C, and D to the THF solution in the specified amounts, add AIBN, and react at 55-70℃ for 6-12 hours under a nitrogen atmosphere.

[0013] The method for preparing the carbon black that adsorbs metal ions is as follows: add carbon black to a ferric chloride solution with a concentration of 0.5wt%-2.0wt%, stir and soak at 100-300 rpm for 2-3 hours, filter, dry, and calcine at 600-700℃ in an oxygen-free environment for 0.5-1 hours to obtain the carbon black.

[0014] Preferably, the molecular weight of polymer I is 10 kDa-100 kDa.

[0015] Secondly, the present invention also provides a method for preparing a semiconductive material for a cable buffer layer, comprising: weighing a vacuum-dried polymer I and carbon black adsorbed with metal ions, stirring them in a high-speed mixer; and finally injecting the mixture into a twin-screw extruder for granulation to obtain the final product.

[0016] The preparation method of the semiconductive material for the cable buffer layer is as follows: Weigh out vacuum-dried polymer I and carbon black adsorbed with metal ions according to weight parts, under nitrogen protection, and stir in a high-speed mixer at 130-150℃ and 800-2000rpm for 10-30min; finally, inject the mixture into a twin-screw extruder with the following parameters: extruder barrel temperatures of 135℃, 145℃, 145℃, 145℃, 145℃, 145℃, 135℃ (distillation head temperature), main extruder speed of 180-240r / min, feed speed of 20-40r / min, and vacuum degree of 0.04-0.1MPa in the vacuum section; granulate to obtain the final product.

[0017] Thirdly, the present invention provides a cable comprising, from the inside out: a conductor, a cable buffer layer, an insulation layer, and a sheath; wherein the cable buffer layer comprises a cable buffer layer semiconductive material.

[0018] Beneficial effects

[0019] This invention provides a semiconductive material for cable buffer layers and its preparation method. The material possesses excellent buffering and protective properties, hydrophobic and moisture-proof properties, flexibility, fire resistance, excellent conductivity, and self-healing properties.

[0020] Intrinsic self-healing function: This is the core advantage. By introducing catechol groups (from monomer C) and carbon black that adsorbs metal ions, a reversible coordination bond network similar to "mussel adhesion" is constructed. When microcracks occur in the material due to stress, the catechol groups on the crack surface can realign with iron ions on the carbon black surface, achieving autonomous crack healing and restoring electrical pathways and mechanical integrity.

[0021] Excellent hydrophobic and moisture-proof properties: The introduction of octafluoroamyl methacrylate (monomer B) endows the polymer with extremely strong hydrophobic and oleophobic properties (low surface energy). This effectively prevents moisture intrusion and fundamentally eliminates the "white spot" problem caused by increased resistance due to moisture in the buffer layer.

[0022] Excellent flame retardant properties: Monomer A contains DOPO and APBIA; DOPO is a highly efficient reactive flame retardant, and APBIA is rich in nitrogen. The two can form a PN synergistic effect, which synergistically improves the flame retardant efficiency and greatly enhances the safety level of the cable.

[0023] Stable high conductivity: Carbon black adsorbed with metal ions: Immersion in FeCl3 solution and high-temperature calcination can effectively improve the conductivity of carbon black, possibly because the iron species (such as Fe3C) formed on its surface can act as conductive points. At the same time, its strong interaction with catechol in the polymer ensures the uniformity and stability of the conductive network in the material, maintaining conductivity even under bending deformation.

[0024] Strong interfacial adhesion: The catechol groups of 4-vinylcatechol (monomer C) have extremely strong adhesion to metals (such as aluminum sheaths) and polar surfaces (such as cable shielding layers). This can significantly improve the contact between the buffer layer and the aluminum sheath, reduce contact resistance, and reduce heat generation caused by poor contact from the source.

[0025] Good flexibility and mechanical strength: 4-n-octylstyrene (monomer D) and the long alkyl chain of monomer D provide internal plasticizing effect, ensuring the flexibility of the material to adapt to cable bending. Attached Figure Description

[0026] Figure 1 Flowchart of the synthesis of monomer A.

[0027] Figure 2 Synthesis flowchart of polymer I.

[0028] Figure 3 Infrared spectrum of monomer A. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. The described embodiments are only some preferred embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Unless otherwise specified, the experimental methods used in the embodiments are conventional or common methods in the art, and the materials and reagents used are commercially available unless otherwise specified.

[0031] The raw materials used in the examples and comparative examples are described below: N,N'-Dicyclohexylcarbodiimide (DCC): purchased from Shandong Jincheng Pharmaceutical Group Co., Ltd.; N-Hydroxysuccinimide (NHS): Purchased from Hubei Xinghengkang Chemical Technology Co., Ltd.; 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO): purchased from Zhengzhou Alpha Chemical Co., Ltd.; 2-(4-Aminophenyl)-5-aminobenzimidazole (APBIA): Purchased from Hubei Henglvyuan Technology Co., Ltd.; Azobisisobutyronitrile (AIBN): Shanghai Aladdin Biochemical Technology Co., Ltd.; Carbon black (1250885): Tianjin Xiens Biochemical Technology Co., Ltd.

[0032] Unless otherwise specified, all components and raw materials used in the embodiments and comparative examples of this invention are commercially available, and the same type of components and raw materials are used in each parallel experiment.

[0033] Preparation of monomer A: A1: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and 2-(4-aminophenyl)-5-aminobenzimidazole (APBIA) were dissolved in anhydrous N-methylpyrrolidone (NMP) (calculated as DOPO: concentration 0.02 g / mL). The reaction was carried out under a nitrogen atmosphere at 120 °C for 6 h. After purification, the intermediate DOPO-APBIA was obtained.

[0034] A2: Dissolve methacrylic acid in N-methylpyrrolidone (NMP) (concentration 0.1 g / mL), add NHS / DCC, stir for 1-3 h to activate the carboxyl group, then add to the NMP solution of intermediate DOPO-APBIA (concentration 0.05 g / mL), stir for 3-5 h; purify to obtain monomer A (see Figure 3 Infrared spectrum of monomer A: The absorption peak of the secondary amine NH of the indole ring is approximately at 3482 cm⁻¹. -1 The NH absorption peak of secondary amide is approximately at 3275 cm⁻¹. -1 The stretching vibration peaks of CH on the unsaturated carbon of benzene rings and olefins appear in the range of 3200-2780 cm⁻¹. -1 The characteristic absorption peak of the phosphorus-oxygen double bond appears at 1230 cm⁻¹. -1 The carbonyl stretching vibration peak of secondary amides appears at 1673 cm⁻¹. -1 ).

[0035] The molar ratio of DOPO, APBIA, and methacrylic acid is 1:1.1:1.05; the molar ratio of methacrylic acid, NHS, and DCC is 1:1.1:1.2.

[0036] Preparation method of carbon black that adsorbs metal ions: Carbon black was added to a 2.0 wt% ferric chloride solution, stirred at 200 rpm for 2 hours, filtered, dried, and calcined at 650℃ in an oxygen-free environment for 0.5 hours to obtain the final product.

[0037] Comparison of preparation methods for carbon black (uncalcined): Add carbon black to a 2.0 wt% ferric chloride solution, stir at 200 rpm and soak for 2 hours, then filter and dry to obtain the final product.

[0038] Example 1

[0039] A method for preparing a semiconductive material for a cable buffer layer: 100 parts by weight of vacuum-dried polymer I and 13 parts by weight of carbon black adsorbing metal ions are weighed, and stirred in a high-speed mixer at 145℃ and 1000rpm for 15min under nitrogen protection; finally, the mixture is injected into a twin-screw extruder with the following parameters: extruder barrel temperatures of 135℃, 145℃, 145℃, 145℃, 145℃, 145℃, 135℃ (distillation head temperature), main extruder speed of 220r / min, feed speed of 30r / min, and vacuum degree of 0.08MPa in the vacuum section; granulation is then performed to obtain the final product.

[0040] The preparation method of polymer I is as follows: S1: Monomers A, B, C, and D were added to a THF solution in the specified amounts, followed by AIBN (0.5% of the total mass of monomers A, B, C, and D). The reaction was carried out under a nitrogen atmosphere at 65°C for 8 hours. The molar ratio of monomers A, B, C, and D was 18:36:27:42. The weight-average molecular weight of polymer I was determined by GPC to be 35600 Da.

[0041] Examples 2-5 The preparation methods of Examples 2-5 are the same as those of Example 1, except that the amount of carbon black used to adsorb metal ions is adjusted and the ratio of each monomer used in the preparation of Polymer I is adjusted.

[0042] Comparative Example 1 The preparation method of Comparative Example 1 is the same as that of Example 1, except that monomer A is missing when preparing polymer I.

[0043] Comparative Example 2 The preparation method of Comparative Example 2 is the same as that of Example 1, except that monomer B is missing when preparing polymer I.

[0044] Comparative Example 3 The preparation method of Comparative Example 3 is the same as that of Example 1, except that monomer C is missing when preparing polymer I.

[0045] Comparative Example 4 The preparation method of Comparative Example 4 is the same as that of Example 1, except that monomer D is missing when preparing polymer I.

[0046] Comparative Example 5 The preparation method of Comparative Example 5 is the same as that of Example 1, except that the carbon black that adsorbs metal ions is replaced with comparative carbon black.

[0047] Comparative Example 6 The preparation method of Comparative Example 6 is the same as that of Example 1, except that the carbon black that adsorbs metal ions is replaced with carbon black (commercially available, which does not adsorb metal ions).

[0048] Table 1 Comparison of preparation methods of the examples and comparative examples

[0049] Performance verification test: Verify the performance of the cable buffer layer semiconductive material prepared in the examples and comparative examples.

[0050] 1. Self-healing performance test Sample preparation: Each sample was processed into a sheet-shaped conductive sample (50mm×50mm×2mm).

[0051] Damage treatment: Use a blade to make a crack in the center of the sample, with a crack depth of 1 / 2 of the sample thickness and a length of 10 mm.

[0052] Repair conditions: Place the damaged sample in an 80℃ oven and let it stand at a constant temperature for 24 hours, then allow it to cool naturally to room temperature.

[0053] Conductivity repair efficiency: Test the volume resistivity before and after repair according to GB / T1410-2006, and calculate the repair efficiency = (volume resistivity before repair - volume resistivity after repair) / volume resistivity before repair × 100%. Parallel test: Perform 3 parallel tests for each group of samples and take the average value.

[0054] 2. Hydrophobicity test Sample preparation: Each sample was processed into a smooth sheet-like sample of 50mm×50mm×2mm, and the surface was wiped with alcohol and then dried.

[0055] Test method: According to GB / T 30693-2014, use a contact angle measuring instrument, add 5μL of deionized water to the sample surface at 25℃ and 50% relative humidity, select 5 different measuring points for each sample, and record the static contact angle.

[0056] 3. Flame retardant performance test Limiting Oxygen Index (LOI) Test: Sample preparation: According to GB / T2406.2-2009, the sample was processed into a strip of 80mm×10mm×4mm.

[0057] Test method: Using an oxygen index meter, the oxygen-nitrogen mixture ratio is adjusted to determine the minimum oxygen concentration required for the sample to maintain combustion.

[0058] 4. Conductivity test Sample preparation: The sample was processed into a sheet-like shape of 50mm×50mm×2mm, with a clean surface free of impurities.

[0059] Test method: According to GB / T1410-2006, use a high resistance meter to measure the volume resistivity (unit: Ω·cm) of the sample at 25℃ and 50% relative humidity. Each sample is measured 3 times and the average value is taken.

[0060] 5. Tensile property test Sample preparation: dumbbell-shaped sample (GB / T1040.1-2006, Type 1A).

[0061] Test method: Tensile strength (MPa) and elongation at break (%) were determined using a tensile testing machine at a tensile speed of 50 mm / min.

[0062] 6. Interface adhesion test Sample preparation: Each sample was hot-pressed with an aluminum sheath for cables (1 mm thick) (temperature 115℃, pressure 0.5 MPa, time 5 min) to prepare a composite sample of 100 mm × 25 mm × 3 mm.

[0063] Test method: According to GB / T2792-2014, use a tensile testing machine to perform a 180° peel test at a speed of 50 mm / min, and determine the peel strength (unit: N / 25 mm). Each sample is tested 3 times and the average value is taken.

[0064] Table 2 Performance Test Record Sheet

[0065] According to the data in Table 2, 1) the conductivity repair rate of Examples 1-5 reached 82%-85%. The core reason is that the catechol group of monomer C (4-vinylcatechol) forms a reversible coordination bond with the iron ions on the surface of carbon black adsorbing metal ions, allowing the crack to heal autonomously. Compared with Example 1, Comparative Example 3 (without monomer C) and Comparative Example 6, which do not contain metal ions in their carbon black, showed a significant decrease in conductivity repair ability. This indicates that the catechol group of monomer C forms a reversible coordination bond with the iron ions on the surface of carbon black adsorbing metal ions, playing a major self-repairing role. The conductivity repair rate of Comparative Example 1 was 78%, which is lower than the recovery rate of Comparative Example 1. This is because the composition of polymer I in Comparative Example 1 lacks monomer A. Monomer A is rich in nitrogen, which easily forms hydrogen bonds with the hydroxyl groups in monomer C, thus enhancing the self-repair function of the material. The comparison between Comparative Example 3 (without monomer C) and Comparative Example 6 also shows that the nitrogen in monomer A easily forms hydrogen bonds with the hydroxyl groups in monomer C, which can help strengthen the self-repair effect. 2) Examples 1-5 have a water contact angle of 123°-126°, exhibiting strong hydrophobicity. As shown in Comparative Example 2, the fluorine in monomer B (octafluoroamyl methacrylate) reduces the surface energy of the material, effectively contributing to hydrophobicity. 3) According to the LOI (Limiting Oxygen Index) measurement, the minimum oxygen concentration range for sustained combustion in Examples 1-5 is 32.2%-33.1%. As shown in Comparative Example 1, monomer A contains DOPO (phosphorus-based flame retardant) and APBIA (nitrogen-based flame retardant), forming a PN synergistic flame retardant effect that effectively improves the fire resistance of the material. 4) Examples 1-5 have a volume resistivity of 71-95 Ω·cm, exhibiting stable conductivity; Comparative Example 6 (commercially available carbon black) has a resistivity of 275 Ω·cm, and Comparative Example 5 (uncalcined carbon black) has a resistivity of 166 Ω·cm. This indicates that after soaking in FeCl3 and high-temperature calcination, Fe3C and other species may be generated on the surface of the carbon black, which can act as conductive points, and their interaction with the polymer is more stable, making it easier to improve conductivity. 5) Examples 1-5 showed elongation at break of 203%-231%; Comparative Example 4 (lacking monomer D) showed an elongation at break of only 170%, proving that the content of monomer D is a key factor in ensuring the flexibility of the material. This is because the long alkyl chain of monomer D (4-n-octylstyrene) provides internal plasticizing, thus improving flexibility. However, the tensile strength of Examples 1-5 ranged from 18.3-18.9 MPa. Comparing Example 1 with Comparative Example 3, it can be seen that the catechol group of monomer C forms reversible coordination bonds with the iron ions on the surface of carbon black adsorbed with metal ions, which can effectively enhance the crosslinking degree between materials and thus improve the tensile strength of the material.6) The peel strength of Examples 1-5 with the aluminum sheath is 8.3-8.8 N / 25 mm, indicating strong adhesion; the peel strength of Comparative Example 3 (lacking monomer C) is only 3.2 N / 25 mm. Because the catechol group of monomer C can form a strong interaction with metallic aluminum, it significantly improves the interface contact between the buffer layer and the aluminum sheath, and can effectively prevent the gap between the buffer layer and the aluminum sheath from increasing due to factors such as bending and impact of the cable. It can effectively reduce the contact resistance and reduce the heat generation caused by poor contact from the source.

[0066] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A semiconductive material for a cable buffer layer, characterized in that, The product comprises, by weight, the following components: 100 parts of polymer I and 10-18 parts of carbon black for adsorbing metal ions; wherein polymer I is obtained by polymerization of monomer A, monomer B: octafluoropentyl methacrylate, monomer C: 4-vinylcatechol, and monomer D: 4-n-octylstyrene, wherein the molar ratio of monomers A, B, C, and D is (15-20):(30-40):(25-30):(40-45); monomer A has the following structural formula: .

2. The semiconductive material for the cable buffer layer according to claim 1, characterized in that, The monomer A is prepared from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide DOPO, 2-(4-aminophenyl)-5-aminobenzimidazole APBIA, and methacrylic acid.

3. The semiconductive material for the cable buffer layer according to claim 2, characterized in that, The molar ratio of DOPO, APBIA, and methacrylic acid is 1:(1.05-1.2):(1.05-1.1).

4. The semiconductive material for the cable buffer layer according to claim 2, characterized in that, The specific preparation method of monomer A is as follows: A1: Dissolve 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 2-(4-aminophenyl)-5-aminobenzimidazole in anhydrous N-methylpyrrolidone (NMP), react at 120±5℃ for 4-8 h under a nitrogen atmosphere, and purify to obtain intermediate DOPO-APBIA. A2: Dissolve methacrylic acid in N-methylpyrrolidone (NMP), add NHS / DCC, stir for 1-3 h to activate the carboxyl group, and then add it to the NMP solution of intermediate DOPO-APBIA and stir for 3-5 h. Purification yields monomer A.

5. The semiconductive material for the cable buffer layer according to claim 1, characterized in that, The preparation method of polymer I is as follows: S1: Add monomers A, B, C, and D to a tetrahydrofuran (THF) solution in the specified amounts, add azobisisobutyronitrile (AIBN), and react at 55-70°C for 6-12 hours under a nitrogen atmosphere.

6. The semiconductive material for the cable buffer layer according to claim 1, characterized in that, The method for preparing the carbon black that adsorbs metal ions is as follows: add carbon black to a ferric chloride solution with a concentration of 0.5wt%-2.0wt%, stir and soak at 100-300 rpm for 2-3 hours, filter, dry, and calcine at 600-700℃ in an oxygen-free environment for 0.5-1 hours to obtain the carbon black.

7. The method for preparing the semiconductive material of the cable buffer layer according to any one of claims 1-6, characterized in that, include: Weigh out the vacuum-dried polymer I and the carbon black that adsorbs metal ions, and stir them in a high-speed mixer; The mixture is then injected into a twin-screw extruder for granulation to obtain the final product.

8. The method for preparing the semiconductive material of the cable buffer layer according to claim 7, characterized in that, Weigh out the vacuum-dried polymer I and the carbon black adsorbed with metal ions according to the specified weight. Under nitrogen protection, stir in a high-speed mixer at 130-150℃ and 800-2000rpm for 10-30min. Finally, inject the mixture into a twin-screw extruder with the following parameters: extruder barrel temperatures of 135℃, 145℃, 145℃, 145℃, 145℃, 145℃, 135℃; main extruder speed of 180-240r / min; feed speed of 20-40r / min; and vacuum degree of 0.04-0.1MPa in the vacuum section. Granulate to obtain the final product.

9. A cable, characterized in that, It comprises, from the inside out, a conductor, a cable buffer layer, an insulation layer, and a sheath; the cable buffer layer contains the semiconductive material of the cable buffer layer as described in any one of claims 1-6.

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