Temperature-resistant and wear-resistant three-layer insulated wire and preparation method thereof

Abstract

The invention discloses a temperature-resistant and wear-resistant three-layer insulated wire and a preparation method thereof, and relates to the technical field of cables. The preparation method comprises the following steps: extruding the inner layer material on the surface of the conductor material to form the inner insulating layer, extruding the modified silicone rubber on the surface of the inner insulating layer to form the middle layer, extruding the outer layer material on the surface of the middle layer to form the outer insulating layer, and curing to obtain the high-temperature-resistant flame-retardant cable material. Wherein the inner-layer material is prepared from low-density polyethylene, an antioxidant 1010, insulating particles, a voltage stabilizer and the like; the modified silicone rubber is prepared from silicone rubber, a boron nitride compound, modified magnesium oxide and the like; the outer-layer material is prepared from the inner-layer material and a boron nitride compound. Due to the introduction of the components such as the insulating particles, the voltage stabilizer and the boron nitride compound, the high voltage resistance, the aging resistance, the wear resistance and the temperature resistance of the crosslinked polyethylene insulated power cable are effectively improved. Therefore, the method has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a heat-resistant and wear-resistant three-layer insulated wire and a preparation method thereof. Background Art

[0002] Cross-linked polyethylene (XLPE) is a modified polymer material formed by cross-linking polyethylene to form a three-dimensional network structure. It exhibits excellent heat resistance, creep resistance, impact resistance, and electrical insulation properties, making it widely used for high-voltage power cable insulation. With the continuous development of ultra-high and ultra-high voltage transmission technology, the voltage level of power cables is constantly increasing, placing increasing demands on the electrical performance of insulation materials, which cannot be met by conventional XLPE materials.

[0003] However, in practical applications, cross-linked polyethylene (XLPE) cable insulation materials still suffer from poor insulation properties under high voltage, aging easily under high temperature and high pressure, and poor wear and high temperature resistance, which limit their application. Therefore, the high voltage resistance, aging resistance, wear resistance, and temperature resistance of existing cross-linked polyethylene (XLPE) cable insulation materials still need to be further improved. Summary of the Invention

[0004] The purpose of the present invention is to provide a heat-resistant and wear-resistant three-layer insulated wire and a preparation method thereof, to solve the following technical problems:

[0005] Existing cross-linked polyethylene insulated power cables still have problems with poor high voltage resistance, aging resistance, wear resistance and temperature resistance.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing a heat-resistant and wear-resistant three-layer insulated wire comprises the following steps:

[0008] An inner layer material is extruded on the surface of the conductor material to form an inner insulating layer with a thickness of 2-3 mm, and then a modified silicone rubber is extruded on the surface of the inner insulating layer to form an intermediate layer with a thickness of 1-2 mm. Then, an outer layer material is extruded on the surface of the intermediate layer to form an outer insulating layer with a thickness of 0.8-1 mm, and the outer layer is cured at 150-170°C and 18 MPa for 3-4 hours to obtain a high-temperature resistant flame-retardant cable material.

[0009] The inner layer material is made of low-density polyethylene, antioxidant 1010, insulating particles, voltage stabilizer, and dicumyl peroxide;

[0010] The modified silicone rubber is made of silicone rubber, boron nitride compound, modified magnesium oxide and dicumyl peroxide;

[0011] The outer layer material is made of the inner layer material and a boron nitride composite;

[0012] The insulating particles are formed by modifying zirconium phosphate nanosheets with a silane coupling agent and then compounding them with MXene coated with silicon dioxide;

[0013] The voltage stabilizer is oxalylbis(p-phenylene)bismaleimide;

[0014] The boron nitride composite is formed by combining hexagonal boron nitride nanotubes with a borazine-ammonia borane prepolymer after being subjected to hydrogen oxide surface treatment;

[0015] The modified magnesium oxide is nano magnesium oxide that is pretreated with a silane coupling agent and then modified with methane plasma.

[0016] Preferably, the preparation method of the inner layer material is as follows:

[0017] Low-density polyethylene was kneaded at 130-140°C for 1-2 minutes, and then antioxidant 1010 was added and kneaded for 2-3 minutes. Then, insulating particles were added and kneaded for 2-3 minutes. Then, a voltage stabilizer was added and ultrasonic-assisted stirring was performed for 8-10 minutes, followed by kneading at 105-110°C for 3-5 minutes. Finally, dicumyl peroxide was added and kneaded for 1-2 minutes to obtain an inner layer material.

[0018] The mass ratio of the low-density polyethylene, antioxidant 1010, insulating particles, voltage stabilizer, and dicumyl peroxide is 400-500:1.2-1.5:0.5-1:1.2-1.5:5.2-6.5.

[0019] Preferably, the preparation method of the modified silicone rubber is as follows:

[0020] After degassing the silicone rubber under vacuum conditions, the boron nitride complex is added and stirred for 10-20 minutes, then the modified magnesium oxide is added and stirred for 20-30 minutes, and finally dicumyl peroxide is added and stirred at 45-55° C. for 30-50 minutes, and then vacuumized to obtain the modified silicone rubber;

[0021] The mass ratio of the silicone rubber, the boron nitride compound, the modified magnesium oxide and the dicumyl peroxide is 100-120:0.8-1.2:5-6:1-1.2.

[0022] Preferably, the outer layer material is prepared as follows:

[0023] Adding the boron nitride compound to the inner layer material and stirring and kneading at 105-110° C. for 3-5 minutes to obtain the outer layer material;

[0024] The mass ratio of the inner layer material to the boron nitride composite is 200-240:1-3.

[0025] Preferably, the preparation method of the insulating particles is as follows:

[0026] A1: Add titanium aluminum carbide powder to a hydrofluoric acid aqueous solution and stir for 20-25 hours. Centrifuge and wash until the pH is 6.5-7.5 after adding deionized water. Then add ethyl orthosilicate and ammonia water and stir at 55-60°C for 2-2.5 hours. Then add to a dimethyl sulfoxide aqueous solution and sonicate for 1-2 hours to obtain MXene colloid.

[0027] A2: Zirconium oxychloride octahydrate and concentrated phosphoric acid were added to deionized water and reacted at 140-150°C for 45-50 hours. The mixture was centrifuged and washed until the pH reached 6-7. The precipitate was added to a tetrabutylammonium hydroxide aqueous solution, sealed, and stirred at 55-60°C for 20-25 hours. Deionized water was then added and ultrasonicated for 30-50 minutes. After centrifugation, the supernatant was vacuum-dried and ground to obtain zirconium phosphate nanosheets.

[0028] A3: Add zirconium phosphate nanosheets to deionized water and sonicate for 20-40 minutes. After adjusting the pH to 3-5, add silane coupling agent KH550 and sonicate for 20-40 minutes. Centrifuge and wash the precipitate, then add it to deionized water. After sonication for 20-30 minutes, add MXene colloid and stir well. Then adjust the pH to 5 and stir at 55-60℃ for 4-6 hours. Centrifuge and dry to obtain insulating particles.

[0029] Preferably, the mass ratio of the hydrofluoric acid aqueous solution, titanium aluminum carbide powder, deionized water, tetraethyl orthosilicate, ammonia water, and dimethyl sulfoxide aqueous solution in A1 is 10-12: 1-1.2: 55-65: 10-12: 5-6: 530-636;

[0030] The mass fraction of the hydrofluoric acid aqueous solution in A1 is 40%;

[0031] The mass fraction of ammonia water described in A1 is 25%;

[0032] The mass fraction of the dimethyl sulfoxide aqueous solution in A1 is 80%-85%;

[0033] The mass ratio of deionized water, zirconium oxychloride octahydrate, concentrated phosphoric acid, and tetrabutylammonium hydroxide aqueous solution in A2 is 200-240:10-12:15-20:100-120;

[0034] The mass fraction of concentrated phosphoric acid in A2 is 85%;

[0035] The mass fraction of the tetrabutylammonium hydroxide aqueous solution in A2 is 5%;

[0036] The mass ratio of deionized water, zirconium phosphate nanosheets, silane coupling agent KH550, deionized water, and MXene colloid described in A3 is 20-24: 0.6-0.7: 0.02-0.04: 1000-1200: 300-360.

[0037] Preferably, the preparation method of the boron nitride composite is as follows:

[0038] B1: dissolving borazine and ammonia borane in tetrahydrofuran and refluxing under nitrogen atmosphere for 5-7 hours, then removing the solvent by distillation under reduced pressure to obtain a prepolymer;

[0039] B2: Add hexagonal boron nitride nanotubes to a hydrogen peroxide solution and ultrasonicate for 2-3 hours. Wash with water until the pH is 6.5-7.5 and then vacuum dry. Then disperse in anhydrous ethanol, add prepolymer and stir under ultrasonication for 1-1.5 hours. After solidification and grinding, obtain a boron nitride composite.

[0040] Preferably, the mass ratio of borazine, ammonia borane and tetrahydrofuran in B1 is 20-24:5-6:100-120;

[0041] The mass ratio of the hydrogen peroxide aqueous solution, hexagonal boron nitride nanotubes, anhydrous ethanol, and prepolymer in B2 is 400-500:8-10:150-200:16-20;

[0042] The mass fraction of the hydrogen peroxide aqueous solution in B2 is 3%-5%.

[0043] Preferably, the preparation method of the modified magnesium oxide is as follows:

[0044] C1: Add nano-magnesium oxide to anhydrous ethanol and ultrasonicate at 45-50°C for 20-40 minutes, then add silane coupling agent KH560 and ultrasonicate for 20-40 minutes, then centrifuge, wash the precipitate, dry it, and grind it to obtain pretreated magnesium oxide;

[0045] C2: Under a methane gas atmosphere, the pretreated magnesium oxide is subjected to a plasma treatment at a pressure of 13-13.5 kPa, a voltage of 10-20 kV, and a frequency of 8-9 kHz for 20-30 min to obtain modified magnesium oxide;

[0046] The mass ratio of anhydrous ethanol, nano-magnesium oxide, and silane coupling agent KH560 in C1 is 20-40:8-10:0.1-0.5.

[0047] Preferably, the preparation method of the voltage stabilizer is as follows:

[0048] D1: Add 4,4'-dichlorobenzil to dimethylformamide and stir well to obtain a 4,4'-dichlorobenzil solution;

[0049] D2: Add maleimide to dimethylformamide and stir well to obtain a maleimide solution;

[0050] D3: Add cuprous iodide to dimethylformamide and stir well to obtain a cuprous iodide solution;

[0051] D4: Add N,N-dimethylethylenediamine and potassium carbonate to dimethylformamide and stir well, then add cuprous iodide solution and stir well, then add 4,4'-dichlorobenzil solution while stirring and stir well, finally add maleimide solution dropwise while stirring at 98-100°C, then reflux at 98-100°C under a nitrogen atmosphere for 8-9 hours, cool and filter, then acid-wash, reduce and wash the filtrate with water to a pH of 6.5-7.5, add anhydrous sodium sulfate to dry, filter and rotary evaporate the filtrate to remove the solvent to obtain a voltage stabilizer.

[0052] Preferably, the mass ratio of dimethylformamide to 4,4'-dichlorobenzil in D1 is 40-80:14-28;

[0053] The mass ratio of dimethylformamide and maleimide in D2 is 50-100:17-34;

[0054] The mass ratio of dimethylformamide and cuprous iodide in D3 is 25-50:0.5-1;

[0055] The mass ratio of dimethylformamide, N,N-dimethylethylenediamine, potassium carbonate, cuprous iodide solution, 4,4'-dichlorobenzil solution and maleimide solution in D4 is 10-20: 0.88-1.76: 0.1-0.2: 25.5-51: 54-108: 67-134.

[0056] Beneficial effects of the present invention:

[0057] The present invention provides a heat-resistant and wear-resistant three-layer insulated wire and a preparation method thereof. The present invention effectively improves the high voltage resistance, aging resistance, wear resistance and temperature resistance of a cross-linked polyethylene insulated power cable through the following method.

[0058] (1) The magnesium oxide in the modified magnesium oxide of the present invention is resistant to high temperatures. After pretreatment with a silane coupling agent and modification with methane plasma, its compatibility with the organic matrix is ​​significantly improved, which can effectively hinder the thermal motion of the matrix molecular chain and delay thermal degradation, thereby improving the temperature resistance and resistance to thermal oxidation aging of the product. Nano-magnesium oxide has a high hardness. After modification, it can reduce the shedding of fillers during friction, while reducing the aggravation of wear caused by interface defects and enhancing the wear resistance of the product. Magnesium oxide is an excellent insulating material. After modification, it can form a continuous insulating network in the matrix, hinder charge migration, and improve or maintain the good insulation of the product. Magnesium oxide can inhibit the growth of electrical dendrites, and after modification, the interface gap is reduced, reducing the aging inducement under the action of voltage, thereby improving the high voltage resistance and electrical aging resistance of the product.

[0059] (2) The hexagonal boron nitride nanotubes in the boron nitride composite of the present invention have extremely high thermal stability and high temperature resistance, and the prepolymer generated by the reaction of borazine and ammonia borane will form a high temperature resistant network after curing. The combination of the two can effectively enhance the thermal stability of the material and improve the temperature resistance. Hexagonal boron nitride nanotubes can improve the hardness and mechanical strength of the material, and the close interface formed with the prepolymer can reduce particle shedding during wear, thereby enhancing wear resistance. Hexagonal boron nitride nanotubes have extremely high surface and volume resistivity and excellent dielectric properties. After compounding, they are uniformly dispersed in the matrix to form an insulating network, effectively hindering carrier migration, improving the insulation resistance of the material, and reducing dielectric loss. At the same time, the prepolymer itself has good insulation properties, which can synergistically improve the overall insulation of the material. Hexagonal boron nitride nanotubes can reduce local electric field concentration, inhibit the growth of electrical trees, and enhance the overall breakdown field strength of the composite material; excellent thermal conductivity helps to quickly dissipate local hot spots, preventing insulation performance degradation or even breakdown due to local overheating; it can also effectively shield aging factors such as oxygen and moisture from diffusing into the polymer matrix; nitrogen and boron-containing prepolymers can inhibit aging degradation under voltage by capturing free radicals and stabilizing molecular chains, and the two together enhance the material's resistance to voltage aging; the high thermal stability of the composite itself helps the matrix resist thermal oxidative aging, and good heat dissipation capacity can reduce the internal operating temperature of the material and slow down the oxidative degradation rate at high temperatures; therefore, the addition of boron nitride composites can significantly slow down the aging rate of the cable insulation layer under the influence of environmental factors such as heat, oxygen, and humidity, thereby extending the service life of the cable.

[0060] (3) The silica layer coated on the surface of the MXene with excellent high temperature resistance in the insulating particles of the present invention further improves its oxidation resistance and thermal stability. At the same time, the zirconium phosphate nanosheets also have extremely high thermal stability. The combination of the two can inhibit the thermal decomposition of the matrix, increase the thermal stability range of the material, and enhance the temperature resistance of the product. The insulating particles can form a good interface with the matrix. Their addition can improve the hardness and mechanical properties of the material, reduce friction and wear, and enhance wear resistance. The silica insulating layer generated in situ on the MXene surface can completely wrap the conductive MXene and block the conductive path. Zirconium phosphate itself is a highly insulating layered material. After modification with a silane coupling agent, it can further modify the MXene and inhibit its conductivity. At the same time, the silane coupling agent treatment improves the compatibility with the matrix and reduces interface defects, thereby improving the insulating properties of the product. Insulating particles within the polymer matrix effectively distort and block the expansion of electrical trees, reducing electric field concentration and the probability of partial discharge and breakdown. The interfaces between the particles and the polymer matrix, as well as defects within the particles themselves, act as traps for charge carriers, reducing the probability of them accelerating into molecular chains under high electric fields and causing breakdown. This improves voltage resistance and, in conjunction with voltage stabilizers, inhibits degradation reactions under voltage, thereby enhancing the product's resistance to electrical aging. The lamellar inorganic particles form a physical barrier, hindering the diffusion and penetration of oxygen, small molecule degradation products, and possible water vapor within the material, significantly slowing the thermal oxidative aging of the polymer matrix.

[0061] (4) The molecular structure of the voltage stabilizer in the present invention contains a large number of conjugated aromatic rings and strong polar groups, which can effectively capture free electrons and holes generated by electric fields, heat or radiation in the material to prevent them from forming conductive channels; it can also change the local electric field distribution and reduce the electric field concentration; it can also effectively inhibit the initiation and growth of electrical dendrites, preventing the insulation layer from being broken down under long-term high voltage; thereby significantly improving the volume resistivity and surface resistivity of the material, reducing dielectric loss, and enhancing its ability to resist local discharge and electrical breakdown, as well as short-term power frequency breakdown voltage, lightning impulse breakdown voltage and long-term withstand voltage life. The voltage stabilizer can significantly improve the material's electrical aging resistance life by inhibiting electrical dendrites and local discharge; it can also improve the overall thermal oxidation stability of the material, while reducing the heat and active substances generated by local discharge, indirectly slowing down the thermal aging process; it can also provide more comprehensive antioxidant protection when used in combination with antioxidant 1010. The improvement of insulation and the ability to inhibit electrothermal effects can also enable the material to maintain its stable electrical properties at higher operating temperatures.

[0062] Therefore, the heat-resistant and wear-resistant three-layer insulated wire prepared by the present invention has excellent high voltage resistance, aging resistance, wear resistance, temperature resistance, and broader application prospects. DETAILED DESCRIPTION

[0063] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0064] Unless otherwise specified, some of the raw materials used in the following examples and comparative examples of the present invention are as follows:

[0065] Silicone rubber (RTV-II type) was purchased from Hebei Zhonglian Huayu Electric Power Technology Co., Ltd.; titanium carbide aluminum powder was purchased from Forsman Technology (Beijing) Co., Ltd., item number: 2203009; low-density polyethylene was purchased from Sinopec Yanshan Branch, model: LD920.

[0066] Example 1: A method for preparing a heat-resistant and wear-resistant three-layer insulated wire is as follows:

[0067] S1: 8 g of nano-magnesium oxide was added to 20 g of anhydrous ethanol and ultrasonically dispersed at 45°C for 20 min. Then, 0.1 g of silane coupling agent KH560 was added and ultrasonically dispersed for 20 min. The mixture was then centrifuged and washed twice with anhydrous ethanol, dried at 75°C, and ground to obtain pretreated magnesium oxide.

[0068] S2: Under a methane gas atmosphere, the pretreated magnesium oxide was subjected to a plasma treatment at a pressure of 13 kPa, a voltage of 10 kV, and a frequency of 8 kHz for 20 min to obtain modified magnesium oxide;

[0069] S3: 20 g of borazine and 5 g of ammonia borane were dissolved in 100 g of tetrahydrofuran and refluxed at 63° C. under a nitrogen atmosphere for 5 h. The solvent was then removed by reduced pressure distillation at 40° C. to obtain a prepolymer;

[0070] S4: 8 g of hexagonal boron nitride nanotubes were added to 400 g of a 3% hydrogen peroxide aqueous solution and ultrasonicated for 2 h. The mixture was washed with water to a pH of 6.5 and then dried in a vacuum oven at 75°C. The mixture was then dispersed in 150 g of anhydrous ethanol. 16 g of a prepolymer was then added and stirred under ultrasonication for 1 h. The mixture was finally cured at 120°C for 1 h and ground to obtain a boron nitride composite.

[0071] S5: 100 g of silicone rubber was degassed under vacuum for 20 min, and then 0.8 g of boron nitride complex was added and stirred for 10 min, followed by 5 g of modified magnesium oxide and stirring for 20 min. Finally, 1 g of dicumyl peroxide was added and stirred at 3000 rpm at 45 °C for 30 min. The modified silicone rubber was obtained after vacuuming for 20 min.

[0072] S6: Add 1 g of titanium aluminum carbide powder to 10 g of a 40% hydrofluoric acid aqueous solution and stir for 20 h. Centrifuge and wash until the pH reaches 6.5 after adding 55 g of deionized water. Then, add 10 g of ethyl orthosilicate and 5 g of 25% ammonia water and stir at 55 ° C for 2 h. Then, add 530 g of an 80% dimethyl sulfoxide aqueous solution and sonicate for 1 h to obtain MXene colloid.

[0073] S7: 10 g of zirconium oxychloride octahydrate and 15 g of 85% concentrated phosphoric acid were added to 200 mL of deionized water and reacted in an autoclave at 140°C for 45 h. After centrifugation and washing until the pH reached 6, the precipitate was added to 100 g of a 5% tetrabutylammonium hydroxide aqueous solution, sealed, and stirred at 55°C for 20 h. 100 g of deionized water was then added and ultrasonicated for 30 min. After centrifugation for 4 min, the supernatant was vacuum-dried at 55°C and ground to obtain zirconium phosphate nanosheets.

[0074] S8: Add 0.6 g of zirconium phosphate nanosheets to 20 mL of deionized water and sonicate for 20 minutes. After adjusting the pH to 3, add 0.02 g of silane coupling agent KH550 and sonicate for 20 minutes. Centrifuge and wash the precipitate twice with anhydrous ethanol and then add it to 1000 mL of deionized water. After sonication for 20 minutes, add 300 g of MXene colloid and stir for 10 minutes. Then adjust the pH to 5 and stir at 55°C for 4 hours. Centrifuge and dry to obtain insulating particles.

[0075] S9: Add 14 g of 4,4'-dichlorobenzil to 40 g of dimethylformamide and stir evenly to obtain a 4,4'-dichlorobenzil solution;

[0076] S10: Add 17 g of maleimide to 50 g of dimethylformamide and stir evenly to obtain a maleimide solution;

[0077] S11: Add 0.5 g of cuprous iodide to 25 g of dimethylformamide and stir evenly to obtain a cuprous iodide solution;

[0078] S12: Add 0.88 g of N,N-dimethylethylenediamine and 0.1 g of potassium carbonate to 10 g of dimethylformamide and stir evenly, then add 25.5 g of cuprous iodide solution and stir for 10 min, then add 54 g of 4,4'-dichlorobenzil solution while stirring and stir for 10 min, finally add 67 g of maleimide solution dropwise while stirring at 98 ° C, then reflux at 98 ° C under a nitrogen atmosphere for 9 h, cool naturally and filter, then acid wash the filtrate, wash with a 1% sodium carbonate aqueous solution for 4 min, and then rinse with deionized water to a pH of 6.5, add anhydrous sodium sulfate to dry, filter and rotary evaporate the filtrate to remove the solvent to obtain a voltage stabilizer;

[0079] S13: 400 g of low-density polyethylene was mixed at 130° C. and 40 rpm for 1 min, followed by adding 1.2 g of antioxidant 1010 and mixing for 2 min, then adding 0.5 g of insulating particles and mixing for 2 min, then adding 1.2 g of voltage stabilizer and ultrasonically stirring for 8 min, followed by mixing at 105° C. for 5 min, and finally adding 5.2 g of diisopropylbenzene peroxide and mixing for 1 min to obtain an inner layer material;

[0080] S14: adding 1 g of the boron nitride composite to 200 g of the inner layer material and stirring and kneading at 105° C. for 5 min to obtain the outer layer material;

[0081] S15: An inner layer material is extruded on the surface of the conductor material to form an inner insulating layer with a thickness of 2 mm, and then a modified silicone rubber is extruded on the surface of the inner insulating layer to form an intermediate layer with a thickness of 1 mm. Then, an outer layer material is extruded on the surface of the intermediate layer to form an outer insulating layer with a thickness of 0.8 mm and cured at 150°C and 18 MPa for 4 hours to obtain a heat-resistant and wear-resistant three-layer insulated wire.

[0082] Example 2: A method for preparing a heat-resistant and wear-resistant three-layer insulated wire is as follows:

[0083] S1: 9 g of nano-magnesium oxide was added to 30 g of anhydrous ethanol and ultrasonically dispersed at 48 ° C for 30 min. Then, 0.3 g of silane coupling agent KH560 was added and ultrasonically dispersed for 30 min. The mixture was then centrifuged and washed with anhydrous ethanol for 3 times, dried at 78 ° C, and ground to obtain pretreated magnesium oxide.

[0084] S2: Under a methane gas atmosphere, the pretreated magnesium oxide was subjected to a plasma treatment at a pressure of 13.3 kPa, a voltage of 15 kV, and a frequency of 8.5 kHz for 25 min to obtain modified magnesium oxide;

[0085] S3: 22 g of borazine and 5.5 g of ammonia borane were dissolved in 110 g of tetrahydrofuran and refluxed at 64° C. under a nitrogen atmosphere for 6 h. The solvent was then removed by distillation under reduced pressure at 45° C. to obtain a prepolymer;

[0086] S4: 9 g of hexagonal boron nitride nanotubes were added to 450 g of a 4% hydrogen peroxide aqueous solution and ultrasonicated for 2.5 h. The mixture was washed with water until the pH reached 7 and then dried under vacuum at 78°C. The mixture was then dispersed in 175 g of anhydrous ethanol. 18 g of a prepolymer was then added and stirred under ultrasonication for 1.2 h. The mixture was finally cured at 130°C for 1.5 h and ground to obtain a boron nitride composite.

[0087] S5: 110 g of silicone rubber was degassed under vacuum for 25 min, followed by the addition of 1 g of boron nitride complex and stirring for 15 min, followed by the addition of 5.5 g of modified magnesium oxide and stirring for 25 min, and finally, the addition of 1.1 g of dicumyl peroxide and stirring at 3500 rpm for 40 min at 50°C, followed by evacuation for 25 min to obtain the modified silicone rubber;

[0088] S6: 1.1 g of titanium aluminum carbide powder was added to 11 g of a 40% hydrofluoric acid aqueous solution and stirred for 23 h. The mixture was centrifuged and washed until the pH reached 7 after adding 60 g of deionized water. 11 g of ethyl orthosilicate and 5.5 g of 25% ammonia water were then added and stirred at 58 ° C for 2.2 h. The mixture was then added to 583 g of an 83% dimethyl sulfoxide aqueous solution and sonicated for 1.5 h to obtain a MXene colloid.

[0089] S7: 11 g zirconium oxychloride octahydrate and 17.5 g 85% concentrated phosphoric acid were added to 220 mL deionized water and reacted in an autoclave at 145°C for 48 h. The mixture was centrifuged and washed until the pH reached 6.5. The precipitate was added to 110 g 5% tetrabutylammonium hydroxide aqueous solution, sealed, and stirred at 58°C for 23 h. 110 g deionized water was then added and ultrasonicated for 40 min. After centrifugation for 5 min, the supernatant was vacuum-dried at 58°C and ground to obtain zirconium phosphate nanosheets.

[0090] S8: 0.65 g of zirconium phosphate nanosheets were added to 22 mL of deionized water and ultrasonicated for 30 min. After adjusting the pH to 4, 0.03 g of silane coupling agent KH550 was added and ultrasonically dispersed for 30 min. The precipitate was centrifuged and washed three times with anhydrous ethanol. It was then added to 1100 mL of deionized water and ultrasonicated for 25 min. 330 g of MXene colloid was added and stirred for 20 min. The pH was then adjusted to 5 and stirred at 58 ° C for 5 h. Insulating particles were obtained after centrifugation and drying.

[0091] S9: Add 21 g of 4,4'-dichlorobenzil to 60 g of dimethylformamide and stir evenly to obtain a 4,4'-dichlorobenzil solution;

[0092] S10: Add 25.5 g of maleimide to 75 g of dimethylformamide and stir evenly to obtain a maleimide solution;

[0093] S11: Add 0.75 g of cuprous iodide to 37.5 g of dimethylformamide and stir well to obtain a cuprous iodide solution;

[0094] S12: Add 1.32 g of N,N-dimethylethylenediamine and 0.15 g of potassium carbonate to 15 g of dimethylformamide and stir evenly. Then add 28.25 g of cuprous iodide solution and stir for 15 min. Then add 81 g of 4,4'-dichlorobenzil solution while stirring and stir for 15 min. Finally, add 100.5 g of maleimide solution dropwise while stirring at 99 ° C., reflux at 99 ° C under a nitrogen atmosphere for 8.5 h, cool naturally and filter, then acid wash the filtrate, wash with a 1% sodium carbonate aqueous solution for 5 min, and then rinse with deionized water to a pH of 7. Add anhydrous sodium sulfate to dry, filter, and evaporate the filtrate to remove the solvent to obtain a voltage stabilizer.

[0095] S13: 450 g of low-density polyethylene was mixed at 135° C. and 50 r / min for 1.5 min, followed by adding 1.35 g of antioxidant 1010 and mixing for 2.5 min, then adding 0.751 g of insulating particles and mixing for 2.5 min, then adding 1.35 g of voltage stabilizer and ultrasonically stirring for 9 min, followed by mixing at 108° C. for 4 min, and finally adding 5.8 g of diisopropylbenzene peroxide and mixing for 1.5 min to obtain an inner layer material;

[0096] S14: Add 2 g of the boron nitride composite to 220 g of the inner layer material and mix at 108° C. for 3-5 minutes to obtain the outer layer material;

[0097] S15: An inner layer material is extruded on the surface of the conductor material to form an inner insulating layer with a thickness of 2.5 mm. Then, a modified silicone rubber is extruded on the surface of the inner insulating layer to form an intermediate layer with a thickness of 1.5 mm. Then, an outer layer material is extruded on the surface of the intermediate layer to form an outer insulating layer with a thickness of 0.9 mm. The outer insulating layer is cured at 160°C and 18 MPa for 3.5 hours to obtain a heat-resistant and wear-resistant three-layer insulated wire.

[0098] Example 3: A method for preparing a heat-resistant and wear-resistant three-layer insulated wire is as follows:

[0099] S1: Add 10 g of nano-magnesium oxide to 40 g of anhydrous ethanol and ultrasonically disperse it at 50°C for 40 min. Then add 0.5 g of silane coupling agent KH560 and ultrasonically disperse it for 40 min. Then, centrifuge and wash the precipitate with anhydrous ethanol four times, then dry it at 80°C and grind it to obtain pretreated magnesium oxide.

[0100] S2: Under a methane gas atmosphere, the pretreated magnesium oxide was subjected to a plasma treatment at a pressure of 13.5 kPa, a voltage of 20 kV, and a frequency of 9 kHz for 30 min to obtain modified magnesium oxide;

[0101] S3: 24 g of borazine and 6 g of ammonia borane were dissolved in 120 g of tetrahydrofuran and refluxed at 65° C. under a nitrogen atmosphere for 7 h. The solvent was then removed by distillation under reduced pressure at 50° C. to obtain a prepolymer;

[0102] S4: 10 g of hexagonal boron nitride nanotubes were added to 500 g of a 5% hydrogen peroxide aqueous solution and ultrasonicated for 3 h. The mixture was washed with water until the pH reached 7.5 and then dried in a vacuum oven at 80°C. The mixture was then dispersed in 200 g of anhydrous ethanol. 20 g of a prepolymer was then added and stirred under ultrasonication for 1.5 h. The mixture was finally cured at 150°C for 2 h and ground to obtain a boron nitride composite.

[0103] S5: 120 g of silicone rubber was degassed under vacuum for 30 min, followed by the addition of 1.2 g of boron nitride complex and stirring for 20 min, followed by the addition of 6 g of modified magnesium oxide and stirring for 30 min, and finally, the addition of 1.2 g of dicumyl peroxide and stirring at 4000 rpm at 55° C. for 50 min. The modified silicone rubber was obtained after vacuuming for 30 min.

[0104] S6: 1.2 g of titanium aluminum carbide powder was added to 12 g of a 40% hydrofluoric acid aqueous solution and stirred for 25 h. The mixture was centrifuged and washed until the pH reached 7.5 after adding 65 g of deionized water. 12 g of ethyl orthosilicate and 6 g of 25% ammonia water were then added and stirred at 60 ° C for 2.5 h. The mixture was then added to 636 g of an 85% dimethyl sulfoxide aqueous solution and ultrasonicated for 2 h to obtain a MXene colloid.

[0105] S7: 12 g of zirconium oxychloride octahydrate and 20 g of 85% concentrated phosphoric acid were added to 240 mL of deionized water and reacted in an autoclave at 150°C for 50 h. The mixture was centrifuged and washed until the pH reached 7. The precipitate was added to 120 g of a 5% tetrabutylammonium hydroxide aqueous solution, sealed, and stirred at 60°C for 25 h. 120 g of deionized water was then added and ultrasonicated for 50 min. After centrifugation for 6 min, the supernatant was vacuum-dried at 60°C and ground to obtain zirconium phosphate nanosheets.

[0106] S8: Add 0.7 g of zirconium phosphate nanosheets to 24 mL of deionized water and sonicate for 40 min. After adjusting the pH to 5, add 0.04 g of silane coupling agent KH550 and sonicate for 40 min. Centrifuge and wash the precipitate four times with anhydrous ethanol and then add it to 1200 mL of deionized water. After sonication for 30 min, add 360 g of MXene colloid and stir for 30 min. Then adjust the pH to 5 and stir at 60 ° C for 4 h. Centrifuge and dry to obtain insulating particles.

[0107] S9: Add 28 g of 4,4'-dichlorobenzil to 80 g of dimethylformamide and stir evenly to obtain a 4,4'-dichlorobenzil solution;

[0108] S10: Add 34 g of maleimide to 100 g of dimethylformamide and stir evenly to obtain a maleimide solution;

[0109] S11: Add 1 g of cuprous iodide to 50 g of dimethylformamide and stir evenly to obtain a cuprous iodide solution;

[0110] S12: Add 1.76 g of N,N-dimethylethylenediamine and 0.2 g of potassium carbonate to 20 g of dimethylformamide and stir evenly, then add 51 g of cuprous iodide solution and stir for 20 min, then add 108 g of 4,4'-dichlorobenzil solution while stirring and stir for 20 min, finally add 134 g of maleimide solution dropwise while stirring at 100 ° C, then reflux at 100 ° C under a nitrogen atmosphere for 9 h, cool naturally and filter, then acid wash the filtrate, wash with a 1% sodium carbonate aqueous solution for 6 min, and then rinse with deionized water to a pH of 7.5, add anhydrous sodium sulfate, dry, filter, and rotary evaporate the filtrate to remove the solvent to obtain a voltage stabilizer;

[0111] S13: 500 g of low-density polyethylene was mixed at 140° C. and 60 rpm for 2 min, followed by adding 1.5 g of antioxidant 1010 and mixing for 3 min, then adding 1 g of insulating particles and mixing for 3 min, then adding 1.5 g of voltage stabilizer and ultrasonically stirring for 10 min, followed by mixing at 110° C. for 3 min, and finally adding 6.5 g of diisopropylbenzene peroxide and mixing for 2 min to obtain an inner layer material;

[0112] S14: Add 3 g of the boron nitride composite to 240 g of the inner layer material and mix at 110° C. for 3 min to obtain the outer layer material;

[0113] S15: An inner layer material is extruded on the surface of the conductor material to form an inner insulating layer with a thickness of 3 mm. Then, a modified silicone rubber is extruded on the surface of the inner insulating layer to form an intermediate layer with a thickness of 2 mm. Then, an outer layer material is extruded on the surface of the intermediate layer to form an outer insulating layer with a thickness of 1 mm. The outer insulating layer is cured at 170°C and 18 MPa for 3 hours to obtain a heat-resistant and wear-resistant three-layer insulated wire.

[0114] Comparative Example 1:

[0115] Compared with Example 1, this comparative example only replaces the "modified magnesium oxide" added in the preparation process of S5 with "pretreated magnesium oxide". The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a heat-resistant and wear-resistant three-layer insulated wire is obtained.

[0116] Comparative Example 2:

[0117] Compared with Example 1, this comparative example only does not add "modified magnesium oxide" during the preparation of S5. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a heat-resistant and wear-resistant three-layer insulated wire is obtained.

[0118] Comparative Example 3:

[0119] Compared with Example 1, this comparative example only replaces the "boron nitride composite" added in the preparation process of S5 with "hexagonal boron nitride nanotubes". The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a heat-resistant and wear-resistant three-layer insulated wire is obtained.

[0120] Comparative Example 4:

[0121] Compared with Example 1, this comparative example only does not perform "adding 10g of ethyl orthosilicate and 5g of 25% ammonia water by mass and stirring at 55°C for 2h" during the preparation process of S6. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a heat-resistant and wear-resistant three-layer insulated wire is obtained.

[0122] Comparative Example 5:

[0123] Compared with Example 1, this comparative example only does not add "MXene colloid" during the preparation of S8. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a heat-resistant and wear-resistant three-layer insulated wire is obtained.

[0124] Comparative Example 6:

[0125] Compared with Example 1, this comparative example only does not add "insulating particles" in the preparation process of S13. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a heat-resistant and wear-resistant three-layer insulated wire is obtained.

[0126] Comparative Example 7:

[0127] Compared with Example 1, this comparative example only does not add the "voltage stabilizer" during the preparation process of S13. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a heat-resistant and wear-resistant three-layer insulated wire is obtained.

[0128] Comparative Example 8:

[0129] Compared with Example 1, this comparative example only does not add the "boron nitride compound" during the preparation of S14. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a heat-resistant and wear-resistant three-layer insulated wire is obtained.

[0130] Performance testing:

[0131] Determination of wear resistance:

[0132] With reference to GB / T 1689-2014 "Determination of wear resistance of vulcanized rubber (using Akron abrasion tester)", the wear loss (cm) of the heat-resistant and wear-resistant three-layer insulated wires prepared in Examples 1 to 3 and Comparative Examples 1 to 8 of the present invention after being rubbed for 1.61 km with a 100-mesh silicon carbide grinding wheel under a constant load of 26.5 N was measured. 3 ), the test results are shown in Table 1;

[0133] Determination of volume resistivity:

[0134] With reference to GB / T 1410-2006, "Test Method for Volume Resistivity and Surface Resistivity of Solid Insulating Materials," the volume resistivity (Ω·m) of the three-layer insulation materials of the heat-resistant and wear-resistant triple-layer insulated wires prepared in Examples 1 to 3 and Comparative Examples 1 to 8 of the present invention was measured at 25°C and 150°C. The test results are shown in Table 1.

[0135] Determination of heat distortion temperature:

[0136] With reference to GB / T 1634.2-2004, "Determination of Deflection Temperature of Plastics under Load - Part 2: Plastics, Ebonite and Long Fiber Reinforced Composite Materials," the heat deformation temperatures (°C) of the three-layer insulation materials of the heat-resistant and wear-resistant triple-layer insulated wires prepared in Examples 1 to 3 and Comparative Examples 1 to 8 of the present invention under a load of 1 MPa were measured. The test results are shown in Table 1.

[0137] Determination of aging resistance:

[0138] With reference to GB / T 2951.12-2008 "General test methods for insulation and sheathing materials of electrical and optical cables - Part 12: General test methods - Thermal aging test method", the tensile strength retention (%) of the three-layer insulation materials of the heat-resistant and wear-resistant three-layer insulated wires prepared in Examples 1 to 3 and Comparative Examples 1 to 8 of the present invention after aging at 150°C for 168 hours was measured. The test results are shown in Table 1.

[0139] Determination of electrical strength:

[0140] With reference to GB / T 1408.1-2016 "Test methods for electrical strength of insulating materials - Part 1: Tests at power frequency", a step-by-step voltage test with a voltage rise rate of 1 kV / s was conducted to measure the DC breakdown voltage of the three-layer insulation materials of the heat-resistant and wear-resistant three-layer insulated wires prepared in Examples 1 to 3 and Comparative Examples 1 to 8 of the present invention at 20°C, and the corresponding electrical strength (kV·mm -1 ), the test results are shown in Table 1.

[0141] Table 1: Performance test results of Examples 1-3 and Comparative Examples 1-8

[0142]

[0143] Data Analysis:

[0144] As can be seen from Table 1, the heat-resistant and wear-resistant three-layer insulated wire prepared in the embodiment of the present invention has excellent wear resistance, insulation, temperature resistance, aging resistance and high voltage resistance.

[0145] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing a heat-resistant and wear-resistant three-layer insulated wire, characterized in that: The following steps are involved: An inner layer material is extruded on the surface of the conductor material to form an inner insulating layer, and then a modified silicone rubber is extruded on the surface of the inner insulating layer to form an intermediate layer, and then an outer layer material is extruded on the surface of the intermediate layer to form an outer insulating layer. After curing, a high-temperature resistant flame-retardant cable material is obtained; The inner layer material is made of low-density polyethylene, antioxidant 1010, insulating particles, voltage stabilizer, and dicumyl peroxide; The modified silicone rubber is made of silicone rubber, boron nitride compound, modified magnesium oxide and dicumyl peroxide; The outer layer material is made of the inner layer material and a boron nitride composite; The insulating particles are formed by modifying zirconium phosphate nanosheets with a silane coupling agent and then compounding them with MXene coated with silicon dioxide; The voltage stabilizer is oxalylbis(p-phenylene)bismaleimide; The boron nitride composite is formed by combining hexagonal boron nitride nanotubes with a borazine-ammonia borane prepolymer after being subjected to hydrogen oxide surface treatment; The modified magnesium oxide is nano magnesium oxide that is pretreated with a silane coupling agent and then modified with methane plasma.

2. The method for preparing the heat-resistant and wear-resistant three-layer insulated wire according to claim 1, characterized in that: The preparation method of the inner layer material is as follows: Low-density polyethylene was kneaded at 130-140°C for 1-2 minutes, and then antioxidant 1010 was added and kneaded for 2-3 minutes. Then, insulating particles were added and kneaded for 2-3 minutes. Then, a voltage stabilizer was added and ultrasonic-assisted stirring was performed for 8-10 minutes, followed by kneading at 105-110°C for 3-5 minutes. Finally, dicumyl peroxide was added and kneaded for 1-2 minutes to obtain an inner layer material. The mass ratio of the low-density polyethylene, antioxidant 1010, insulating particles, voltage stabilizer, and dicumyl peroxide is 400-500:1.2-1.5:0.5-1:1.2-1.5:5.2-6.

5.

3. The method for preparing the heat-resistant and wear-resistant three-layer insulated wire according to claim 1, characterized in that: The preparation method of the modified silicone rubber is as follows: After degassing the silicone rubber under vacuum conditions, the boron nitride complex is added and stirred evenly, and then the modified magnesium oxide is added and stirred evenly, and finally dicumyl peroxide is added and stirred at 45-55° C. for 30-50 minutes, and then vacuumed to obtain the modified silicone rubber; The mass ratio of the silicone rubber, the boron nitride compound, the modified magnesium oxide and the dicumyl peroxide is 100-120:0.8-1.2:5-6:1-1.

2.

4. The method for preparing the heat-resistant and wear-resistant three-layer insulated wire according to claim 1, characterized in that: The preparation method of the outer layer material is as follows: Adding the boron nitride compound to the inner layer material and stirring and kneading at 105-110° C. for 3-5 minutes to obtain the outer layer material; The mass ratio of the inner layer material to the boron nitride composite is 200-240:1-3.

5. The method for preparing the heat-resistant and wear-resistant three-layer insulated wire according to claim 1, characterized in that: The preparation method of the insulating particles is as follows: A1: Add titanium aluminum carbide powder to a hydrofluoric acid aqueous solution and stir for 20-25 hours. Centrifuge and wash until the pH is 6.5-7.5 after adding deionized water. Then add ethyl orthosilicate and ammonia water and stir at 55-60°C for 2-2.5 hours. Then add to a dimethyl sulfoxide aqueous solution and sonicate for 1-2 hours to obtain MXene colloid. A2: Zirconium oxychloride octahydrate and concentrated phosphoric acid were added to deionized water and reacted at 140-150°C for 45-50 hours. The mixture was centrifuged and washed until the pH reached 6-7. The precipitate was added to a tetrabutylammonium hydroxide aqueous solution, sealed, and stirred at 55-60°C for 20-25 hours. Deionized water was then added and ultrasonicated for 30-50 minutes. After centrifugation, the supernatant was vacuum-dried and ground to obtain zirconium phosphate nanosheets. A3: Add zirconium phosphate nanosheets to deionized water and sonicate for 20-40 minutes. After adjusting the pH to 3-5, add silane coupling agent KH550 and sonicate for 20-40 minutes. Centrifuge and wash the precipitate, then add it to deionized water. After sonication for 20-30 minutes, add MXene colloid and stir well. Then adjust the pH to 5 and stir at 55-60℃ for 4-6 hours. Centrifuge and dry to obtain insulating particles.

6. The method for preparing the heat-resistant and wear-resistant three-layer insulated wire according to claim 5, characterized in that: The mass ratio of the hydrofluoric acid aqueous solution, titanium aluminum carbide powder, deionized water, ethyl orthosilicate, ammonia water, and dimethyl sulfoxide aqueous solution in A1 is 10-12:1-1.2:55-65:10-12:5-6:530-636; The mass fraction of the hydrofluoric acid aqueous solution in A1 is 40%; The mass fraction of ammonia water described in A1 is 25%; The mass fraction of the dimethyl sulfoxide aqueous solution in A1 is 80%-85%; The mass ratio of deionized water, zirconium oxychloride octahydrate, concentrated phosphoric acid, and tetrabutylammonium hydroxide aqueous solution in A2 is 200-240:10-12:15-20:100-120; The mass fraction of concentrated phosphoric acid in A2 is 85%; The mass fraction of the tetrabutylammonium hydroxide aqueous solution in A2 is 5%; The mass ratio of deionized water, zirconium phosphate nanosheets, silane coupling agent KH550, deionized water, and MXene colloid described in A3 is 20-24: 0.6-0.7: 0.02-0.04: 1000-1200: 300-360.

7. The method for preparing the heat-resistant and wear-resistant three-layer insulated wire according to claim 1, characterized in that: The preparation method of the boron nitride composite is as follows: B1: dissolving borazine and ammonia borane in tetrahydrofuran and refluxing under nitrogen atmosphere for 5-7 hours, then removing the solvent by distillation under reduced pressure to obtain a prepolymer; B2: Add hexagonal boron nitride nanotubes to a hydrogen peroxide solution and ultrasonicate for 2-3 hours. Wash with water until the pH is 6.5-7.5 and then vacuum dry. Then disperse in anhydrous ethanol, add prepolymer and stir under ultrasonication for 1-1.5 hours. After solidification and grinding, obtain a boron nitride composite.

8. The method for preparing the heat-resistant and wear-resistant three-layer insulated wire according to claim 1, characterized in that: The mass ratio of borazine, ammonia borane and tetrahydrofuran in B1 is 20-24:5-6:100-120; The mass ratio of the hydrogen peroxide aqueous solution, hexagonal boron nitride nanotubes, anhydrous ethanol, and prepolymer in B2 is 400-500:8-10:150-200:16-20; The mass fraction of the hydrogen peroxide aqueous solution in B2 is 3%-5%.

9. The method for preparing the heat-resistant and wear-resistant three-layer insulated wire according to claim 1, characterized in that: The preparation method of the modified magnesium oxide is as follows: C1: Add nano-magnesium oxide to anhydrous ethanol and ultrasonicate at 45-50°C for 20-40 minutes, then add silane coupling agent KH560 and ultrasonicate for 20-40 minutes, then centrifuge, wash the precipitate, dry it, and grind it to obtain pretreated magnesium oxide; C2: Plasma treatment of the pretreated magnesium oxide in a methane gas atmosphere to obtain modified magnesium oxide; The mass ratio of anhydrous ethanol, nano-magnesium oxide, and silane coupling agent KH560 in C1 is 20-40:8-10:0.1-0.

5.

10. A heat-resistant and wear-resistant three-layer insulated wire, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.

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