Parallel reinforced overhead insulated cable

Abstract

The invention belongs to the technical field of cables, and particularly relates to a parallel reinforced overhead insulated cable. The preparation method comprises the following steps: carrying out a reaction on polyvinyl alcohol and trithiocarbonate to form polyvinyl alcohol-CTA with an RAFT functional group, then carrying out a free radical polymerization reaction on the polyvinyl alcohol-CTA and vinylidene fluoride to generate a triblock copolymer, and finally, carrying out a reaction on bismaleimide and a diene part in the triblock copolymer to obtain the self-healing weather-resistant additive. The self-healing insulating layer material with higher weather resistance is obtained by mixing the self-healing insulating layer material with cross-linked polyethylene, and the self-healing insulating layer material is applied to parallel reinforced overhead insulated cables, shows excellent durability, low maintainability and long-term reliability, and is very suitable for being used in various severe environments.

Description

Technical Field

[0001] The invention belongs to the technical field of cables, and in particular relates to a parallel reinforced overhead insulated cable. Background Art

[0002] In our daily life, wherever there are people living, wherever there are life, production, transportation and all economic activities, electricity is indispensable. The generation, transmission and application of electricity must use wires and cables as connecting and transmitting components or as winding materials of the host. Cables are usually laid in overhead, underwater, tunnel and buried ways. Reasonable selection of cable laying methods is very important to ensure the transmission quality, reliability and construction and maintenance of the line. When laying the cable, it should be protected from mechanical external force, overheating, laying and other hazards, and it is easy to lay and maintain. Among them, overhead insulated cables have an extra layer of insulation, so they have superior insulation than bare wires, which can reduce the phase-to-phase distance of the line, reduce the insulation requirements for the support parts of the line, increase the number of loops of the line on the same pole, and are less susceptible to oxidation corrosion than bare wires, have stronger corrosion resistance, and can extend the service life of the line. However, overhead cables are easily affected by wind and rain loads, resulting in tensile stress and shaking.

[0003] However, the insulation layer of traditional overhead insulated cables is made of cross-linked polyethylene material, which has a high dielectric strength and can withstand high voltage without electrical breakdown. This makes it the preferred material for high-voltage and ultra-high-voltage cable insulators. However, as the insulation layer of overhead insulated cables, its weather resistance needs to be further improved. In addition, due to the difficulty of high-altitude maintenance and high replacement costs, how to make the cable automatically repair when it is microscopically damaged, reduce material degradation caused by environmental stress or mechanical stress, and reduce maintenance costs has also become a new research direction. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a parallel reinforced overhead insulated cable.

[0005] The invention provides a parallel reinforced overhead insulated cable, comprising a plurality of wire cores, a wrapping tape wrapping the plurality of wire cores, an inner sheath wrapping the wrapping tape, and a self-healing weather-resistant insulating layer wrapping the inner sheath.

[0006] The wire core is composed of a conductor and an insulating layer wrapping the conductor, and the insulating layer is made of polypropylene.

[0007] The wrapping tape is a double-sided water-blocking tape with a thickness of 0.2-0.3 mm and an overlap rate of 25%-30%.

[0008] The material of the inner protective layer is polypropylene.

[0009] The material used for the self-healing weather-resistant insulation layer is a self-healing weather-resistant cable insulation material, and the preparation method thereof comprises the following steps: (1) 1-3 g of polyvinyl alcohol and 10-30 mL of anhydrous ethanol were mixed and stirred for 10-30 min, 0.01-0.1 g of 4-dimethylaminopyridine was added, and the mixture was stirred for 5-10 min under nitrogen protection to obtain precursor A; 0.1-1 g of trithiocarbonate and 0.2-0.3 g of dicyclohexylcarbodiimide were dissolved in 10-30 mL of anhydrous ethanol, and the mixture was added dropwise at a rate of 1-5 mL / min under stirring at 55-65 °C. After the addition of precursor A is completed, the reaction is carried out for 10-16 hours, cooled to room temperature, filtered to remove the by-product dicyclohexylurea, washed with n-hexane 3-4 times, washed with saturated sodium chloride solution and separated 1-2 times, and the organic phase is retained; finally, the organic phase is dried with anhydrous magnesium sulfate, filtered and the n-hexane is evaporated under reduced pressure to obtain polyvinyl alcohol-CTA; the polyvinyl alcohol-CTA has an Mn of 5100-5300 g / mol and an Ð of 1.2-1.4; (2) Dissolve 0.5-2 g of vinylidene fluoride, 0.5-2 g of polyvinyl alcohol-CTA obtained in step (1), 0.2-1 g of hexafluoropropylene, and 0.01-0.03 g of 4,4'-azobis(4-cyanovaleric acid) in 10-30 mL of dimethylformamide, and stir at 75-85° C. for 6-10 h in a nitrogen atmosphere. After the reaction is completed, pour 40-60 mL of methanol, let stand for 10-20 min, filter to obtain a precipitate, wash with alcohol 1-2 times, wash with water 1-2 times, and finally dry at 30-50° C. to obtain a triblock copolymer; (3) dissolving 0.5-2 g of the triblock copolymer obtained in step (2) and 0.2-1 g of bismaleimide in 10-30 mL of chloroform, stirring and reacting at 45-55° C. for 18-30 h. After the reaction is completed, cooling to room temperature and evaporating the solvent to obtain a self-healing weather-resistant additive; (4) The self-healing weather-resistant additive obtained in step (3) and cross-linked polyethylene are mixed in a mass ratio of 1:(4-6), extruded by a twin-screw extruder, and cooled to room temperature to obtain the self-healing weather-resistant cable insulation material.

[0010] The temperature of the feeding zone of the twin-screw extruder is 160-180°C, the temperature of the compression zone is 180-200°C, the temperature of the metering zone is 200-220°C, the temperature of the die mouth is 200-210°C, and the screw speed is 50-150r / min.

[0011] Aiming at the defects of overhead insulated cables being difficult to repair and greatly affected by the natural environment, the present invention prepares a self-healing weather-resistant cable insulation material to enhance the self-repairing ability and weather resistance of traditional cross-linked polyethylene insulation layers.

[0012] The present invention uses polyvinyl alcohol to react with the carboxyl group in trithiocarbonate, and DMAP is used as a catalyst to accelerate the speed of the esterification reaction. Under the action of dicyclohexylcarbodiimide, the carboxyl group is activated to form an amide bond, and then reacts with the hydroxyl group of polyvinyl alcohol to form an ester bond, forming polyvinyl alcohol-CTA with a RAFT functional group. The RAFT functional group is a special chemical group used to control free radical polymerization reactions during the RAFT polymerization process. The RAFT functional group is usually composed of trithiocarbonate (dithioester) and dithiocarbamate. These functional groups can react with the active activation on the polymer chain to control the structure of the molecular chain through a reversible addition-fragmentation process.

[0013] Next, polyvinyl alcohol-CTA and vinylidene fluoride undergo free radical polymerization to generate a triblock copolymer. During this process, polyethylene, as an intermediate block, undergoes free radical polymerization with vinylidene fluoride to form a polymer with a uniformly distributed chain length.

[0014] Finally, bismaleimide reacts with the diene part in the triblock copolymer to form a stable cross-linked structure. The reaction here is a thermally reversible cycloaddition reaction. When the material is heated, a reverse reaction occurs, breaking the cross-linking bonds. When the temperature drops to room temperature, the cross-linking bonds are reformed, thereby repairing the microscopic damage of the material and achieving self-healing.

[0015] When subjected to external physical damage (such as cracks or scratches), the local temperature of the material rises and a reverse reaction occurs, breaking the original cross-linking bonds. As the temperature recovers, the material re-cross-links, filling the cracks and achieving self-healing.

[0016] Beneficial effects of the present invention: The polyethylene block has good compatibility with cross-linked polyethylene, which can ensure that the material can form a uniform phase distribution during the blending process, avoid phase separation, and improve the mechanical strength and insulation performance of the cable. The introduction of the vinylidene fluoride block further enhances the hydrophobicity of the material, making the cable show better water resistance and corrosion resistance in a humid environment, extending the service life of the cable. The uniform distribution and good compatibility of the triblock copolymer ensure the high strength and toughness of the material, allowing the cable to withstand greater physical stress and environmental changes in long-term use.

[0017] The self-healing ability provided by the self-healing weather-resistant additive enables the cable to automatically repair itself when it is microscopically damaged, reducing material degradation caused by environmental or mechanical stress and lowering maintenance costs.

[0018] Through the preparation scheme of the above new materials, the triblock copolymer not only has excellent hydrophobicity and self-healing ability, but also has good compatibility with traditional cable insulation materials. This material shows excellent durability, low maintenance and long-term reliability in cable insulation applications, and is very suitable for use in various harsh environments. DETAILED DESCRIPTION

[0019] The conductor material of the wire core described in each embodiment and comparative example is copper.

[0020] Polyvinyl alcohol, CAS number: 9002-89-5, Mn=5,200 g / mol, Ð=1.3.

[0021] Cross-linked polyethylene, model: LS4201S, Shanghai Changshi Plastics Co., Ltd.

[0022] Polypropylene alcohol, model: PPG-4000, Sangda Chemical (Nantong) Co., Ltd.

[0023] Dihydroxypolydimethylsiloxane, product number: xyh001, Hubei Xinyuhong Biopharmaceutical Technology Co., Ltd.

[0024] Trithiocarbonate, CAS number: 461642-78-4.

[0025] Dicyclohexylcarbodiimide, CAS number: 538-75-0.

[0026] Bismaleimide, CAS number: 13676-54-5.

[0027] Example 1

[0028] A parallel reinforced overhead insulated cable comprises a plurality of wire cores, a wrapping tape wrapping the plurality of wire cores, an inner sheath wrapping the wrapping tape, and a self-healing weather-resistant insulating layer wrapping the inner sheath.

[0029] The wire core is composed of a conductor and an insulating layer wrapping the conductor, and the insulating layer is made of polypropylene.

[0030] The wrapping tape is a double-sided water-blocking tape with a thickness of 0.25 mm and an overlap rate of 28%.

[0031] The material of the inner protective layer is polypropylene.

[0032] The material used for the self-healing weather-resistant insulation layer is a self-healing weather-resistant cable insulation material, and the preparation method thereof comprises the following steps: (1) 2 g of polyvinyl alcohol and 20 mL of anhydrous ethanol were mixed and stirred for 15 min, 0.05 g of 4-dimethylaminopyridine was added, and the mixture was stirred for 5 min under nitrogen protection to obtain a precursor A; 0.5 g of trithiocarbonate and 0.25 g of dicyclohexylcarbodiimide were dissolved in 20 mL of anhydrous ethanol, and added dropwise to the precursor A at 4 mL / min under stirring at 60 ° C. After the addition was completed, the mixture was reacted for 12 h, cooled to room temperature, filtered, washed with n-hexane 3 times, washed with saturated sodium chloride solution and separated 2 times, and the organic phase was retained; finally, the organic phase was dried with anhydrous magnesium sulfate, filtered, and the n-hexane was evaporated under reduced pressure to obtain polyvinyl alcohol-CTA; the polyvinyl alcohol-CTA had Mn=5200 g / mol and Ð=1.3; (2) Dissolve 1 g of vinylidene fluoride, 1 g of polyvinyl alcohol-CTA obtained in step (1), 0.5 g of hexafluoropropylene, and 0.02 g of 4,4'-azobis(4-cyanovaleric acid) in 20 mL of dimethylformamide, and stir at 80°C for 8 h in a nitrogen atmosphere. After the reaction is completed, pour 50 mL of methanol, let stand for 15 min, filter the precipitate, wash it twice with alcohol, wash it twice with water, and finally dry it at 40°C to obtain a triblock copolymer; (3) Dissolve 1 g of the triblock copolymer obtained in step (2) and 0.5 g of bismaleimide in 20 mL of chloroform, stir and react at 50 °C for 24 h. After the reaction is completed, cool to room temperature and evaporate the solvent to obtain a self-healing weather-resistant additive; (4) The self-healing weather-resistant additive obtained in step (3) and cross-linked polyethylene are mixed in a mass ratio of 1:4, extruded using a twin-screw extruder, and cooled to room temperature to obtain the self-healing weather-resistant cable insulation material.

[0033] The twin-screw extruder has a feeding zone temperature of 170° C., a compression zone temperature of 190° C., a metering zone temperature of 210° C., a die port temperature of 205° C., and a screw speed of 120 r / min.

[0034] Example 2

[0035] A parallel reinforced overhead insulated cable comprises a plurality of wire cores, a wrapping tape wrapping the plurality of wire cores, an inner sheath wrapping the wrapping tape, and a self-healing weather-resistant insulating layer wrapping the inner sheath.

[0036] The wire core is composed of a conductor and an insulating layer wrapping the conductor, and the insulating layer is made of polypropylene.

[0037] The wrapping tape is a double-sided water-blocking tape with a thickness of 0.25 mm and an overlap rate of 28%.

[0038] The material of the inner protective layer is polypropylene.

[0039] The material used for the self-healing weather-resistant insulation layer is a self-healing weather-resistant cable insulation material, and the preparation method thereof comprises the following steps: (1) 2 g of polyvinyl alcohol and 20 mL of anhydrous ethanol were mixed and stirred for 15 min, 0.05 g of 4-dimethylaminopyridine was added, and the mixture was stirred for 5 min under nitrogen protection to obtain a precursor A; 0.5 g of trithiocarbonate and 0.25 g of dicyclohexylcarbodiimide were dissolved in 20 mL of anhydrous ethanol, and added dropwise to the precursor A at 4 mL / min under stirring at 60 ° C. After the addition was completed, the mixture was reacted for 12 h, cooled to room temperature, filtered, washed with n-hexane 3 times, washed with saturated sodium chloride solution and separated 2 times, and the organic phase was retained; finally, the organic phase was dried with anhydrous magnesium sulfate, filtered, and the n-hexane was evaporated under reduced pressure to obtain polyvinyl alcohol-CTA; the polyvinyl alcohol-CTA had Mn=5200 g / mol and Ð=1.3; (2) Dissolve 1 g of vinylidene fluoride, 1 g of polyvinyl alcohol-CTA obtained in step (1), 0.5 g of hexafluoropropylene, and 0.02 g of 4,4'-azobis(4-cyanovaleric acid) in 20 mL of dimethylformamide, and stir at 80°C for 8 h in a nitrogen atmosphere. After the reaction is completed, pour 50 mL of methanol, let stand for 15 min, filter the precipitate, wash it twice with alcohol, wash it twice with water, and finally dry it at 40°C to obtain a triblock copolymer; (3) Dissolve 1 g of the triblock copolymer obtained in step (2) and 0.5 g of bismaleimide in 20 mL of chloroform, stir and react at 50 °C for 24 h. After the reaction is completed, cool to room temperature and evaporate the solvent to obtain a self-healing weather-resistant additive; (4) The self-healing weather-resistant additive obtained in step (3) and cross-linked polyethylene are mixed in a mass ratio of 1:2, extruded using a twin-screw extruder, and cooled to room temperature to obtain the self-healing weather-resistant cable insulation material.

[0040] The twin-screw extruder has a feeding zone temperature of 170° C., a compression zone temperature of 190° C., a metering zone temperature of 210° C., a die port temperature of 205° C., and a screw speed of 120 r / min.

[0041] Example 3

[0042] A parallel reinforced overhead insulated cable comprises a plurality of wire cores, a wrapping tape wrapping the plurality of wire cores, an inner sheath wrapping the wrapping tape, and a self-healing weather-resistant insulating layer wrapping the inner sheath.

[0043] The wire core is composed of a conductor and an insulating layer wrapping the conductor, and the insulating layer is made of polypropylene.

[0044] The wrapping tape is a double-sided water-blocking tape with a thickness of 0.25 mm and an overlap rate of 28%.

[0045] The material of the inner protective layer is polypropylene.

[0046] The material used for the self-healing weather-resistant insulation layer is a self-healing weather-resistant cable insulation material, and the preparation method thereof comprises the following steps: (1) 2 g of polyvinyl alcohol and 20 mL of anhydrous ethanol were mixed and stirred for 15 min, 0.05 g of 4-dimethylaminopyridine was added, and the mixture was stirred for 5 min under nitrogen protection to obtain a precursor A; 0.5 g of trithiocarbonate and 0.25 g of dicyclohexylcarbodiimide were dissolved in 20 mL of anhydrous ethanol, and added dropwise to the precursor A at 4 mL / min under stirring at 60 ° C. After the addition was completed, the mixture was reacted for 12 h, cooled to room temperature, filtered, washed with n-hexane 3 times, washed with saturated sodium chloride solution and separated 2 times, and the organic phase was retained; finally, the organic phase was dried with anhydrous magnesium sulfate, filtered, and the n-hexane was evaporated under reduced pressure to obtain polyvinyl alcohol-CTA; the polyvinyl alcohol-CTA had Mn=5200 g / mol and Ð=1.3; (2) Dissolve 1 g of vinylidene fluoride, 1 g of polyvinyl alcohol-CTA obtained in step (1), 0.5 g of hexafluoropropylene, and 0.02 g of 4,4'-azobis(4-cyanovaleric acid) in 20 mL of dimethylformamide, and stir at 80°C for 8 h in a nitrogen atmosphere. After the reaction is completed, pour 50 mL of methanol, let stand for 15 min, filter the precipitate, wash it twice with alcohol, wash it twice with water, and finally dry it at 40°C to obtain a triblock copolymer; (3) Dissolve 1 g of the triblock copolymer obtained in step (2) and 0.5 g of bismaleimide in 20 mL of chloroform, stir and react at 50 °C for 24 h. After the reaction is completed, cool to room temperature and evaporate the solvent to obtain a self-healing weather-resistant additive; (4) The self-healing weather-resistant additive obtained in step (3) and cross-linked polyethylene are mixed in a mass ratio of 1:6, extruded using a twin-screw extruder, and cooled to room temperature to obtain the self-healing weather-resistant cable insulation material.

[0047] The twin-screw extruder has a feeding zone temperature of 170° C., a compression zone temperature of 190° C., a metering zone temperature of 210° C., a die port temperature of 205° C., and a screw speed of 120 r / min.

[0048] Comparative Example 1

[0049] A parallel reinforced overhead insulated cable comprises a plurality of wire cores, a wrapping tape wrapping the plurality of wire cores, an inner sheath wrapping the wrapping tape, and an insulating layer wrapping the inner sheath.

[0050] The wire core is composed of a conductor and an insulating layer wrapping the conductor, and the insulating layer is made of polypropylene.

[0051] The wrapping tape is a double-sided water-blocking tape with a thickness of 0.25 mm and an overlap rate of 28%.

[0052] The material of the inner protective layer is polypropylene.

[0053] The insulating layer is made of cross-linked polyethylene.

[0054] Comparative Example 2

[0055] A parallel reinforced overhead insulated cable comprises a plurality of wire cores, a wrapping tape wrapping the plurality of wire cores, an inner sheath wrapping the wrapping tape, and a self-healing weather-resistant insulating layer wrapping the inner sheath.

[0056] The wire core is composed of a conductor and an insulating layer wrapping the conductor, and the insulating layer is made of polypropylene.

[0057] The wrapping tape is a double-sided water-blocking tape with a thickness of 0.25 mm and an overlap rate of 28%.

[0058] The material of the inner protective layer is polypropylene.

[0059] The material used for the self-healing weather-resistant insulation layer is a self-healing weather-resistant cable insulation material, and the preparation method thereof comprises the following steps: (1) 2 g of polyvinyl alcohol and 20 mL of anhydrous ethanol were mixed and stirred for 15 min, 0.05 g of 4-dimethylaminopyridine was added, and the mixture was stirred for 5 min under nitrogen protection to obtain a precursor A; 0.5 g of trithiocarbonate and 0.25 g of dicyclohexylcarbodiimide were dissolved in 20 mL of anhydrous ethanol, and added dropwise to the precursor A at 4 mL / min under stirring at 60 ° C. After the addition was completed, the mixture was reacted for 12 h, cooled to room temperature, filtered, washed with n-hexane 3 times, washed with saturated sodium chloride solution and separated 2 times, and the organic phase was retained; finally, the organic phase was dried with anhydrous magnesium sulfate, filtered, and the n-hexane was evaporated under reduced pressure to obtain polyvinyl alcohol-CTA; the polyvinyl alcohol-CTA had Mn=5200 g / mol and Ð=1.3; (2) Dissolve 1 g of vinylidene fluoride, 1 g of polyvinyl alcohol-CTA obtained in step (1), 0.5 g of hexafluoropropylene, and 0.02 g of 4,4'-azobis(4-cyanovaleric acid) in 20 mL of dimethylformamide, and stir at 80°C for 8 h in a nitrogen atmosphere. After the reaction is completed, pour 50 mL of methanol, let stand for 15 min, filter the precipitate, wash it twice with alcohol, wash it twice with water, and finally dry it at 40°C to obtain a triblock copolymer; (3) Dissolving 1 g of the triblock copolymer obtained in step (2) and 0.5 g of maleic anhydride in 20 mL of chloroform, stirring and reacting at 50 °C for 24 h. After the reaction is completed, cooling to room temperature and evaporating the solvent to obtain a self-healing weather-resistant additive; (4) The self-healing weather-resistant additive obtained in step (3) and cross-linked polyethylene are mixed in a mass ratio of 1:4, extruded using a twin-screw extruder, and cooled to room temperature to obtain the self-healing weather-resistant cable insulation material.

[0060] The twin-screw extruder has a feeding zone temperature of 170° C., a compression zone temperature of 190° C., a metering zone temperature of 210° C., a die port temperature of 205° C., and a screw speed of 120 r / min.

[0061] Comparative Example 3

[0062] A parallel reinforced overhead insulated cable comprises a plurality of wire cores, a wrapping tape wrapping the plurality of wire cores, an inner sheath wrapping the wrapping tape, and a self-healing weather-resistant insulating layer wrapping the inner sheath.

[0063] The wire core is composed of a conductor and an insulating layer wrapping the conductor, and the insulating layer is made of polypropylene.

[0064] The wrapping tape is a double-sided water-blocking tape with a thickness of 0.25 mm and an overlap rate of 28%.

[0065] The material of the inner protective layer is polypropylene.

[0066] The material used for the self-healing weather-resistant insulation layer is a self-healing weather-resistant cable insulation material, and the preparation method thereof comprises the following steps: (1) 2 g of polyvinyl alcohol and 20 mL of anhydrous ethanol were mixed and stirred for 15 min, 0.05 g of 4-dimethylaminopyridine was added, and the mixture was stirred for 5 min under nitrogen protection to obtain a precursor A; 0.5 g of trithiocarbonate and 0.25 g of dicyclohexylcarbodiimide were dissolved in 20 mL of anhydrous ethanol, and added dropwise to the precursor A at 4 mL / min under stirring at 60 ° C. After the addition was completed, the mixture was reacted for 12 h, cooled to room temperature, filtered, washed with n-hexane 3 times, washed with saturated sodium chloride solution and separated 2 times, and the organic phase was retained; finally, the organic phase was dried with anhydrous magnesium sulfate, filtered, and the n-hexane was evaporated under reduced pressure to obtain polyvinyl alcohol-CTA; the polyvinyl alcohol-CTA had Mn=5200 g / mol and Ð=1.3; (2) Dissolve 1 g of vinylidene fluoride, 1 g of polyvinyl alcohol-CTA obtained in step (1), 0.5 g of hexafluoropropylene, and 0.02 g of 4,4'-azobis(4-cyanovaleric acid) in 20 mL of dimethylformamide, and stir at 80°C for 8 h in a nitrogen atmosphere. After the reaction is completed, pour 50 mL of methanol, let stand for 15 min, filter the precipitate, wash it twice with alcohol, wash it twice with water, and finally dry it at 40°C to obtain a triblock copolymer; (3) Dissolve 1 g of the triblock copolymer obtained in step (2) and 0.5 g of dimethyl fumarate in 20 mL of chloroform, stir and react at 50 °C for 24 h. After the reaction is completed, cool to room temperature and evaporate the solvent to obtain a self-healing weather-resistant additive; (4) The self-healing weather-resistant additive obtained in step (3) and cross-linked polyethylene are mixed in a mass ratio of 1:4, extruded using a twin-screw extruder, and cooled to room temperature to obtain the self-healing weather-resistant cable insulation material.

[0067] The twin-screw extruder has a feeding zone temperature of 170° C., a compression zone temperature of 190° C., a metering zone temperature of 210° C., a die port temperature of 205° C., and a screw speed of 120 r / min.

[0068] Comparative Example 4

[0069] A parallel reinforced overhead insulated cable comprises a plurality of wire cores, a wrapping tape wrapping the plurality of wire cores, an inner sheath wrapping the wrapping tape, and a self-healing weather-resistant insulating layer wrapping the inner sheath.

[0070] The wire core is composed of a conductor and an insulating layer wrapping the conductor, and the insulating layer is made of polypropylene.

[0071] The wrapping tape is a double-sided water-blocking tape with a thickness of 0.25 mm and an overlap rate of 28%.

[0072] The material of the inner protective layer is polypropylene.

[0073] The material used for the self-healing weather-resistant insulation layer is a self-healing weather-resistant cable insulation material, and the preparation method thereof comprises the following steps: (1) 2 g of polypropylene alcohol and 20 mL of anhydrous ethanol were mixed and stirred for 15 min, 0.05 g of 4-dimethylaminopyridine was added, and the mixture was stirred for 5 min under nitrogen protection to obtain a precursor A; 0.5 g of trithiocarbonate and 0.25 g of dicyclohexylcarbodiimide were dissolved in 20 mL of anhydrous ethanol, and added dropwise to the precursor A at 4 mL / min under stirring at 60 ° C. After the addition was completed, the mixture was reacted for 12 h, cooled to room temperature, filtered, washed with n-hexane 3 times, washed with saturated sodium chloride solution and separated 2 times, and the organic phase was retained; finally, the organic phase was dried with anhydrous magnesium sulfate, filtered, and the n-hexane was evaporated under reduced pressure to obtain polyvinyl alcohol-CTA; the polyvinyl alcohol-CTA had Mn=5200 g / mol and Ð=1.3; (2) Dissolve 1 g of vinylidene fluoride, 1 g of polyvinyl alcohol-CTA obtained in step (1), 0.5 g of hexafluoropropylene, and 0.02 g of 4,4'-azobis(4-cyanovaleric acid) in 20 mL of dimethylformamide, and stir at 80°C for 8 h in a nitrogen atmosphere. After the reaction is completed, pour 50 mL of methanol, let stand for 15 min, filter the precipitate, wash it twice with alcohol, wash it twice with water, and finally dry it at 40°C to obtain a triblock copolymer; (3) Dissolve 1 g of the triblock copolymer obtained in step (2) and 0.5 g of bismaleimide in 20 mL of chloroform, stir and react at 50 °C for 24 h. After the reaction is completed, cool to room temperature and evaporate the solvent to obtain a self-healing weather-resistant additive; (4) The self-healing weather-resistant additive obtained in step (3) and cross-linked polyethylene are mixed in a mass ratio of 1:4, extruded using a twin-screw extruder, and cooled to room temperature to obtain the self-healing weather-resistant cable insulation material.

[0074] The twin-screw extruder has a feeding zone temperature of 170° C., a compression zone temperature of 190° C., a metering zone temperature of 210° C., a die port temperature of 205° C., and a screw speed of 120 r / min.

[0075] Comparative Example 5

[0076] A parallel reinforced overhead insulated cable comprises a plurality of wire cores, a wrapping tape wrapping the plurality of wire cores, an inner sheath wrapping the wrapping tape, and a self-healing weather-resistant insulating layer wrapping the inner sheath.

[0077] The wire core is composed of a conductor and an insulating layer wrapping the conductor, and the insulating layer is made of polypropylene.

[0078] The wrapping tape is a double-sided water-blocking tape with a thickness of 0.25 mm and an overlap rate of 28%.

[0079] The material of the inner protective layer is polypropylene.

[0080] The material used for the self-healing weather-resistant insulation layer is a self-healing weather-resistant cable insulation material, and the preparation method thereof comprises the following steps: (1) 2 g of dihydroxy polydimethylsiloxane and 20 mL of anhydrous ethanol were mixed and stirred for 15 min, 0.05 g of 4-dimethylaminopyridine was added, and the mixture was stirred for 5 min under nitrogen protection to obtain a precursor A; 0.5 g of trithiocarbonate and 0.25 g of dicyclohexylcarbodiimide were dissolved in 20 mL of anhydrous ethanol, and added dropwise to the precursor A at 4 mL / min under stirring at 60 ° C. After the addition was completed, the mixture was reacted for 12 h, cooled to room temperature, filtered, washed with n-hexane 3 times, washed with saturated sodium chloride solution and separated 2 times, and the organic phase was retained; finally, the organic phase was dried with anhydrous magnesium sulfate, filtered, and the n-hexane was evaporated under reduced pressure to obtain polyvinyl alcohol-CTA; the polyvinyl alcohol-CTA had Mn=5200 g / mol and Ð=1.3; (2) Dissolve 1 g of vinylidene fluoride, 1 g of polyvinyl alcohol-CTA obtained in step (1), 0.5 g of hexafluoropropylene, and 0.02 g of 4,4'-azobis(4-cyanovaleric acid) in 20 mL of dimethylformamide, and stir at 80°C for 8 h in a nitrogen atmosphere. After the reaction is completed, pour 50 mL of methanol, let stand for 15 min, filter the precipitate, wash it twice with alcohol, wash it twice with water, and finally dry it at 40°C to obtain a triblock copolymer; (3) Dissolve 1 g of the triblock copolymer obtained in step (2) and 0.5 g of bismaleimide in 20 mL of chloroform, stir and react at 50 °C for 24 h. After the reaction is completed, cool to room temperature and evaporate the solvent to obtain a self-healing weather-resistant additive; (4) The self-healing weather-resistant additive obtained in step (3) and cross-linked polyethylene are mixed in a mass ratio of 1:4, extruded using a twin-screw extruder, and cooled to room temperature to obtain the self-healing weather-resistant cable insulation material.

[0081] The twin-screw extruder has a feeding zone temperature of 170° C., a compression zone temperature of 190° C., a metering zone temperature of 210° C., a die port temperature of 205° C., and a screw speed of 120 r / min.

[0082] Test Example 1

[0083] Self-healing performance test: Take two portions of the self-healing weather-resistant cable insulation materials prepared in Examples 1-3, Comparative Examples 2-5, and the cross-linked polyethylene in Comparative Example 1, cut one portion in the middle, and the cut area is 4 / 5 of the cross-sectional area. Then place it at 80-120°C and let it stand for 12 hours. Take it out, observe its healing area, and compare it with the uncut self-healing weather-resistant cable insulation material. Test the change in its elongation at break, and record the reduction in elongation at break. Sample size: 10cm*5cm*2cm. The results are shown in Table 1.

[0084] Table 1: Self-healing performance test results

[0085] Test Example 2

[0086] The self-healing weather-resistant cable insulation materials prepared in Examples 1-3 and Comparative Examples 2-5 and the cross-linked polyethylene used in Comparative Example 1 were subjected to heat aging tests. The heat aging tests were conducted in accordance with GB / T 2951.12-2008 "General test methods for insulation and sheathing materials for electric and optical cables Part 12: General test methods - Heat aging test methods". The aging resistance of the material was judged by the difference in elongation at break before and after aging. The results are shown in Table 2.

[0087] Table 2: Reduction in elongation at break

[0088] It can be seen from Table 1 and Table 2 that the self-healing weather-resistant cable insulation material used in Examples 1-3 shows good healing performance. However, with the reduction of the amount of self-healing weather-resistant additives, its self-healing ability and heat aging resistance are significantly reduced, while the amount of self-healing weather-resistant additives is increased, and its self-healing ability and heat aging resistance are not significantly improved. These results show that the material can effectively self-heal after cutting, and the mechanical properties (such as ductility) of the material after healing are maintained at a high level, and the self-healing weather-resistant additive and cross-linked polyethylene are mixed at a mass ratio of 1:4, which is the best ratio. In Comparative Example 1, no self-healing material is used, so the healing area is 0, and the elongation at break is reduced by 25.7%, which performs poorly in the heat aging test, which shows that ordinary cross-linked polyethylene cannot self-heal after damage, and the damage greatly reduces its mechanical properties. Comparative Examples 2-3 use different self-healing enhancers, but the effects are not as good as those of Examples 1-3. The healing area is relatively small, the elongation at break is reduced, and the anti-aging performance is also poor. These results show that although these comparative examples have a certain self-healing ability, the performance is poor, and the mechanical properties of the materials after self-healing cannot be fully restored. Comparative Examples 4-5 use polyvinyl alcohol to replace polyvinyl alcohol and dihydroxy polydimethylsiloxane to replace polyvinyl alcohol, respectively, and their performance is relatively poor and cannot achieve the effect of the example material.

Claims

1. A parallel reinforced overhead insulated cable, characterized in that: The parallel reinforced overhead insulated cable comprises a plurality of wire cores, a wrapping tape wrapping the plurality of wire cores, an inner sheath wrapping the wrapping tape, and a self-healing weather-resistant insulating layer wrapping the inner sheath.

2. The parallel reinforced overhead insulated cable according to claim 1, characterized in that: The wire core is composed of a conductor and an insulating layer wrapping the conductor, and the insulating layer is made of polypropylene.

3. The parallel reinforced overhead insulated cable according to claim 1, characterized in that: The wrapping tape is a double-sided water-blocking tape with a thickness of 0.2-0.3 mm and an overlap rate of 25%-30%.

4. The parallel reinforced overhead insulated cable according to claim 1, characterized in that: The material of the inner protective layer is polypropylene.

5. The parallel reinforced overhead insulated cable according to claim 1, characterized in that: The material used for the self-healing weather-resistant insulation layer is a self-healing weather-resistant cable insulation material, and the preparation method thereof comprises the following steps: (1) 1-3 g of polyvinyl alcohol and 10-30 mL of anhydrous ethanol were mixed and stirred for 10-30 min, 0.01-0.1 g of 4-dimethylaminopyridine was added, and the mixture was stirred for 5-10 min under nitrogen protection to obtain a precursor A; 0.1-1 g of trithiocarbonate and 0.2-0.3 g of dicyclohexylcarbodiimide were dissolved in 10-30 mL of anhydrous ethanol, and added dropwise to the precursor A at a rate of 1-5 mL / min under stirring conditions at 55-65 ° C. After the addition was completed, the mixture was reacted for 10-16 h, cooled to room temperature, filtered to remove the by-product dicyclohexylurea, washed with n-hexane 3-4 times, washed with saturated sodium chloride solution, separated 1-2 times, and the organic phase was retained; finally, the organic phase was dried with anhydrous magnesium sulfate, filtered, and the n-hexane was evaporated under reduced pressure to obtain polyvinyl alcohol-CTA; (2) Dissolve 0.5-2 g of vinylidene fluoride, 0.5-2 g of polyvinyl alcohol-CTA obtained in step (1), 0.2-1 g of hexafluoropropylene, and 0.01-0.03 g of 4,4'-azobis(4-cyanovaleric acid) in 10-30 mL of dimethylformamide, and stir at 75-85° C. for 6-10 h in a nitrogen atmosphere. After the reaction is completed, pour 40-60 mL of methanol, let stand for 10-20 min, filter to obtain a precipitate, wash with alcohol 1-2 times, wash with water 1-2 times, and finally dry at 30-50° C. to obtain a triblock copolymer; (3) dissolving 0.5-2 g of the triblock copolymer obtained in step (2) and 0.2-1 g of bismaleimide in 10-30 mL of chloroform, stirring and reacting at 45-55° C. for 18-30 h. After the reaction is completed, cooling to room temperature and evaporating the solvent to obtain a self-healing weather-resistant additive; (4) The self-healing weather-resistant additive obtained in step (3) is mixed with cross-linked polyethylene, extruded using a twin-screw extruder, and cooled to room temperature to obtain the self-healing weather-resistant cable insulation material.

6. The parallel reinforced overhead insulated cable as claimed in claim 5, characterized in that: The Mn of the polyvinyl alcohol-CTA in step (1) is 5100-5300 g / mol, and Ð is 1.2-1.

4.

7. The parallel reinforced overhead insulated cable as claimed in claim 5, characterized in that: The mass ratio of the self-healing weather-resistant additive to the cross-linked polyethylene in step (4) is 1:(4-6).

8. The parallel reinforced overhead insulated cable as claimed in claim 5, characterized in that: In step (4), the temperature of the feeding zone of the twin-screw extruder is 160-180°C, the temperature of the compression zone is 180-200°C, the temperature of the metering zone is 200-220°C, the temperature of the die mouth is 200-210°C, and the screw speed is 50-150r / min.

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