A steel wire reinforced core overhead insulated cable

Abstract

This application relates to the field of wire and cable technology, specifically disclosing a steel wire reinforced core overhead insulated cable. The steel wire reinforced core overhead insulated cable includes a conductor core, an insulation layer, and a sheath; the conductor core is formed by stranding a steel wire reinforcing core with an aluminum conductor; the surface of the steel wire reinforcing core is coated with an epoxy resin coating. The insulation layer includes high-density polyethylene, a crosslinking agent, a co-crosslinking agent, an antioxidant, a light stabilizer, nano-zinc oxide, nano-alumina, and a silane coupling agent; the sheath includes crosslinked polyethylene, an antioxidant, a UV absorber, zinc stearate, aluminum hydroxide, silicon nitride, and a silane coupling agent. The overhead insulated cable obtained by this application has a maximum tensile strength, elongation at break, tensile strength, and conductor breaking force of 79.2 MPa, 490%, 20.0 MPa, and 80.6 kN, respectively, and the lowest 42-day tensile strength and elongation at break changes of 3% and 5%, respectively, improving the mechanical strength and weather resistance of the overhead insulated cable.

Description

Technical Field

[0001] This application relates to the field of wire and cable technology, and more specifically, to a steel wire reinforced core overhead insulated cable. Background Technology

[0002] Overhead insulated conductors are used for power transmission and distribution, typically in overhead power lines. They need to possess both reliable insulation performance and good mechanical strength to withstand their own weight, wind, snow, and other external forces during use. Traditional overhead insulated cables, some of which use a single conductor structure, are prone to breakage and deformation when facing harsh environments and significant external forces, affecting the stability and reliability of power transmission.

[0003] In related technologies, steel wire reinforcing cores are added to cables to improve their mechanical strength. However, steel wires are prone to electrochemical or chemical corrosion in humid, salt spray, and acid rain environments, producing rust. The expansion of rust can compress the internal structure of the cable, leading to insulation layer rupture, sheath bulging, and even steel wire breakage. This results in poor cable weather resistance, easy aging, and safety hazards such as leakage and short circuits.

[0004] With the continuous growth of electricity demand and the increasing requirements for power transmission quality, it is urgent to develop an overhead insulated cable with high mechanical strength, excellent insulation performance and long service life. Summary of the Invention

[0005] In order to improve the mechanical strength and weather resistance of overhead insulated conductors, this application provides an overhead insulated cable with steel wire reinforced core.

[0006] In a first aspect, this application provides a steel wire reinforced core overhead insulated cable, which adopts the following technical solution:

[0007] A steel wire reinforced core overhead insulated cable includes a conductor core, an insulation layer, and a sheath; the conductor core is formed by twisting a steel wire reinforced core with several aluminum profile single wires; the surface of the steel wire reinforced core is coated with an epoxy resin coating.

[0008] The sheath comprises the following raw materials in parts by weight: 80-100 parts cross-linked polyethylene, 0.5-1 part antioxidant, 0.5-1 part ultraviolet absorber, 0.5-1.5 parts zinc stearate, 15-30 parts aluminum hydroxide, 5-15 parts silicon nitride, and 1-2 parts silane coupling agent.

[0009] The insulation layer of the steel wire reinforced core overhead insulated cable of this application comprises the following raw materials in parts by weight: 90-100 parts of high-density polyethylene, 0.5-1 parts of crosslinking agent, 0.1-0.5 parts of co-crosslinking agent, 0.5-1 parts of antioxidant, 2-3 parts of light stabilizer, 3-5 parts of nano zinc oxide, 1-3 parts of nano aluminum oxide, and 0.5-1 parts of silane coupling agent.

[0010] The insulation layer of the steel wire reinforced core overhead insulated cable of this application is made of 90-100 parts high-density polyethylene, 0.5-1 part crosslinking agent, 0.1-0.5 parts co-crosslinking agent, 0.5-1 part antioxidant, 2-3 parts light stabilizer, 3-5 parts nano zinc oxide, 1-3 parts nano aluminum oxide, and 0.5-1 part silane coupling agent. Any value within the respective ranges can be selected, which can improve the mechanical strength and weather resistance of the overhead insulated conductor. In addition, the sheath of the steel wire reinforced core overhead insulated cable of this application is made of 80-100 parts crosslinked polyethylene, 0.5-1 part antioxidant, 0.5-1 part ultraviolet absorber, 0.5-1.5 parts zinc stearate, 15-30 parts aluminum hydroxide, 5-15 parts silicon nitride, and 1-2 parts silane coupling agent. Any value within the respective ranges can be selected, which can also improve the mechanical strength and weather resistance of the overhead insulated conductor.

[0011] By adopting the above technical solution, the conductor core is formed by twisting a steel wire reinforcing core with several aluminum conductors, which can improve the mechanical strength of the overhead insulated cable. The surface of the steel wire reinforcing core is coated with an epoxy resin coating. After curing, the epoxy resin forms a three-dimensional network polymer structure with high hardness and tensile strength. On the one hand, it can form a "rigid-flexible" composite system with the steel wire. When the steel wire is subjected to tensile or bending loads, the epoxy resin coating disperses the stress over a larger area through interfacial shear force, reducing stress concentration on the steel wire surface, thereby improving the fracture resistance of the overhead insulated cable and thus increasing its mechanical strength. On the other hand, the epoxy resin coating can effectively prevent corrosive media such as moisture, oxygen, salt spray, and acid / alkali solutions from contacting the steel wire, cutting off the electrochemical corrosion path. Furthermore, the epoxy resin coating has good chemical resistance and is not easily degraded by ultraviolet light, ozone, or high temperatures, thus preventing long-term oxidation of the conductor core and improving the weather resistance of the overhead insulated cable.

[0012] The insulation layer uses high-density polyethylene as the main raw material to ensure the insulation and flexibility of the overhead insulated cable. A cross-linking agent initiates cross-linking of polyethylene molecules, forming a three-dimensional network structure and improving the mechanical strength of the insulation layer. A co-cross-linking agent promotes uniform cross-linking, reduces cross-linking byproducts, shortens cross-linking time, increases cross-linking density, or improves the uniformity of the cross-linking network, thereby further improving the mechanical strength of the insulation layer. Antioxidants are added to improve the oxidation resistance of the insulation layer and ensure its weather resistance. Light stabilizers capture ultraviolet-induced active particles, inhibiting photo-oxidation of the overhead insulated cable and improving its weather resistance. Nano-zinc oxide can improve the mechanical strength of the overhead insulated cable and also has an ultraviolet shielding effect, reducing photo-degradation and improving weather resistance. Nano-alumina fills the gaps in the high-density polyethylene, improving the mechanical strength of the insulation layer. A silane coupling agent can improve the interfacial bonding force between nano-zinc oxide, nano-alumina, and other additives and high-density polyethylene, improving the dispersion uniformity of each raw material in the insulation layer, thereby improving the mechanical strength and weather resistance of the overhead insulated cable.

[0013] The sheath uses cross-linked polyethylene as the main raw material, providing the sheath's basic mechanical strength and insulation, giving it high weather resistance, heat resistance, and mechanical strength. Antioxidants prevent oxidation reactions in overhead insulated cables during processing and at high temperatures, improving the sheath's weather resistance. UV absorbers absorb UV energy, preventing it from causing polymer molecular chain breakage, thus preventing sheath cracking and improving weather resistance. Zinc stearate reduces the melt viscosity of cross-linked polyethylene, reducing frictional heat generation during extrusion, improving the sheath's surface smoothness, preventing material adhesion to equipment, inhibiting polymer degradation, and improving production efficiency. Aluminum hydroxide, uniformly dispersed in the cross-linked polyethylene matrix in crystalline particle form, forms a rigid skeleton to bear external mechanical loads, improving the sheath's hardness and deformation resistance. Silicon nitride, as a "reinforcing phase," hinders molecular chain slippage, significantly improving wear resistance and tear strength, enhancing the sheath's weather resistance, and increasing its resistance to chemical corrosion. The simultaneous addition of aluminum hydroxide and silicon nitride allows silicon nitride to compensate for the decrease in toughness caused by aluminum hydroxide, preventing the sheath from becoming brittle. The two form a "rigid-flexible complementary" structure, simultaneously improving the mechanical strength and weather resistance of the sheath. Silane coupling agents improve the compatibility of aluminum hydroxide, silicon nitride, and cross-linked polyethylene, reducing agglomeration and increasing the mechanical strength of the sheath.

[0014] Preferably, the sheath comprises the following raw materials in parts by weight: 85-95 parts cross-linked polyethylene, 0.7-0.9 parts antioxidant, 0.7-0.9 parts ultraviolet absorber, 0.7-1.3 parts zinc stearate, 20-25 parts aluminum hydroxide, 7-13 parts silicon nitride, and 1.3-1.7 parts silane coupling agent.

[0015] The insulation layer of the steel wire reinforced core overhead insulated cable of this application is made of 93-97 parts of high-density polyethylene, 0.7-0.9 parts of crosslinking agent, 0.2-0.4 parts of co-crosslinking agent, 0.7-0.9 parts of antioxidant, 2.3-2.7 parts of light stabilizer, 3.5-4.5 parts of nano zinc oxide, 1.5-2.5 parts of nano aluminum oxide, and 0.7-0.9 parts of silane coupling agent. Any value within the respective range can be selected, which can improve the mechanical strength and weather resistance of the overhead insulated conductor. In addition, the sheath of the steel wire reinforced core overhead insulated cable of this application is made of 85-95 parts of cross-linked polyethylene, 0.7-0.9 parts of antioxidant, 0.7-0.9 parts of ultraviolet absorber, 0.7-1.3 parts of zinc stearate, 20-25 parts of aluminum hydroxide, 7-13 parts of silicon nitride, and 1.3-1.7 parts of silane coupling agent. Any value within the respective range can be selected, which can improve the mechanical strength and weather resistance of the overhead insulated conductor.

[0016] As a preferred embodiment, the specific method for spraying an epoxy resin coating onto the surface of the steel wire reinforcing core is as follows: first, the steel wire is degreased and deoiled, and then sandblasted with quartz sand of 80-120 mesh at a sandblasting pressure of 0.4-0.6 MPa to achieve a roughness of Ra5-10 μm. Then, the steel wire is preheated at 180-220℃ for 10-15 min, epoxy resin is sprayed, and cured at 180-200℃ for 20-30 min, followed by natural cooling. The thickness of the sprayed epoxy resin is 0.12-0.18 mm, and the epoxy resin particle size is 80-120 mesh.

[0017] By adopting the above technical solution, the steel wire is first degreased and deoiled to remove oil stains, hand sweat, etc., ensuring that there are no obvious oil residues on the surface, thus improving the adhesion of epoxy resin to the steel wire surface. Sandblasting is then performed to make the steel wire surface uniformly glossy and rough to the touch, increasing the adhesion of the epoxy resin coating, forming microscopic anchor points, and preventing the epoxy resin coating from peeling off.

[0018] Preferably, the weight ratio of silicon nitride to aluminum hydroxide is 1:(2-3).

[0019] By adopting the above technical solution and adjusting the weight ratio of silicon nitride to aluminum hydroxide, the mechanical strength and weather resistance of the sheath can be further improved, thereby improving the mechanical strength and weather resistance of the overhead insulated cable.

[0020] Preferably, the silicon nitride is prepared by modification, specifically:

[0021] S1. Wash silicon nitride with ethanol solution, then add silicon nitride to 5% dilute hydrochloric acid solution and ultrasonically disperse for 30-40 min, filter, wash until neutral, dry, add to silane coupling agent-ethanol mixed solution, stir and react at 75-85℃ for 2-3 h to obtain pretreated silicon nitride;

[0022] S2. Add methyl methacrylate to acetone and mix, stirring until homogeneous to obtain a methyl methacrylate solution;

[0023] S3. Add the pretreated silicon nitride to a methyl methacrylate solution, add benzoyl peroxide, stir under nitrogen and 60-80℃ for 2-3 hours, precipitate, filter, wash, and vacuum dry to obtain modified silicon nitride.

[0024] Wherein, the acetone is 2-3 times the mass of methyl methacrylate; the amount of benzoyl peroxide is 1-2% of the mass of methyl methacrylate; and the amount of silane coupling agent in the silane coupling agent-ethanol mixed solution is 10-15% of the ethanol.

[0025] By adopting the above technical solution, silicon nitride is first cleaned with ethanol solution to remove surface impurities. Then, it is added to 5% dilute hydrochloric acid and ultrasonically dispersed to increase the number of surface hydroxyl groups. It is then added to a silane coupling agent-ethanol mixed solution, where covalent bonds are formed through hydrolysis-condensation reaction, which is beneficial for subsequent methyl methacrylate grafting and improves the interfacial bonding between silicon nitride and methyl methacrylate. The pretreated silicon nitride is then added to a methyl methacrylate solution, and benzoyl peroxide initiator is added. The solution is stirred for 2-3 hours under nitrogen and 60-80℃ conditions, allowing methyl methacrylate to undergo free radical polymerization at the double bonds on the silicon nitride surface, forming a polymethyl methacrylate graft layer. This improves the compatibility between silicon nitride and the sheath material, avoids particle agglomeration, and can further improve the mechanical strength and weather resistance of overhead insulated cables.

[0026] Preferably, the mass ratio of silicon nitride to methyl methacrylate is 1:(0.5-1.5).

[0027] By adopting the above technical solution and adjusting the mass ratio of silicon nitride to methyl methacrylate, the formation of a polymethyl methacrylate graft layer on the surface of silicon nitride becomes more uniform, further improving the compatibility between silicon nitride and the sheath material, thereby enhancing the mechanical strength and weather resistance of overhead insulated cables.

[0028] Preferably, the sheath also includes aramid fibers and glass fibers.

[0029] By adopting the above technical solution, the addition of aramid fibers to the sheath provides high toughness and impact resistance, absorbing external stress. Aramid fibers can bear most of the load through molecular chain orientation, preventing sheath cracking, avoiding premature yielding of cross-linked polyethylene, and improving the mechanical strength of the sheath. Glass fibers, with high rigidity and tensile strength, can provide skeletal support in the sheath, inhibiting sheath deformation and improving its mechanical strength. Furthermore, the simultaneous addition of aramid and glass fibers reduces interface defects in the sheath. Under external force, aramid fibers delay crack propagation, while glass fibers hinder the straight-line propagation of cracks, forming an interpenetrating network structure within the cross-linked polyethylene, thus enhancing the mechanical strength of the sheath.

[0030] In addition, the benzene ring and amide bond in the molecular structure of aramid fiber form a conjugated system that can absorb ultraviolet energy and inhibit the photo-oxidative degradation of the sheath. Glass fiber can reflect some ultraviolet rays and physically block the penetration of moisture and oxygen, thereby improving the sheath's resistance to ultraviolet rays, heat and chemical corrosion, and thus improving the sheath's weather resistance.

[0031] Preferably, the weight ratio of the aramid fiber to the glass fiber is 1:(1-2).

[0032] By adopting the above technical solution and adjusting the weight ratio of aramid fiber to glass fiber, it is beneficial to further improve the mechanical strength and weather resistance of overhead insulated cables.

[0033] In summary, this application includes at least one of the following beneficial technical effects:

[0034] (1) This application improves the mechanical strength and weather resistance of overhead insulated cables by spraying an epoxy resin coating on the surface of the steel wire reinforcing core and controlling the types and amounts of raw materials in the insulation layer and sheath. The tensile strength, elongation at break and tensile strength of the overhead insulated cable are 73.5-74.2 MPa, 473-476% and 17.7-19.1 MPa respectively, and the conductor breaking force is 80.6 kN. After 42 days of weather resistance testing, the change rates of tensile strength and elongation at break of the overhead insulated cable are 13-16% and 18-19% respectively.

[0035] (2) This application modifies the silicon nitride in the sheath material to make the tensile strength, elongation at break and tensile strength of the overhead insulated cable 75.2-76.1MPa, 481-484% and 18.7-19.0MPa respectively. After 42 days of weather resistance testing, the change rate of tensile strength and elongation at break of the overhead insulated cable is 7-8% and 10-13% respectively, which further improves the mechanical strength and weather resistance of the overhead insulated cable.

[0036] (3) This application adds aramid fiber and glass fiber to the sheath material and controls the weight ratio of the two to make the tensile strength, elongation at break and tensile strength of the overhead insulated cable 77.5-79.2MPa, 487-490% and 19.5-20.0MPa respectively. After 42 days of weather resistance test, the change rate of tensile strength and elongation at break of the overhead insulated cable is 3-5% and 5-7% respectively, which further improves the mechanical strength and weather resistance of the overhead insulated cable. Detailed Implementation

[0037] The present application will be further described in detail below with reference to specific embodiments.

[0038] The following raw materials used in this application are all commercially available products and are intended to fully disclose the raw materials used in this application. They should not be construed as limiting the source of the raw materials. Specifically: aluminum conductor, model LG-70; epoxy resin, model bisphenol A epoxy resin E-12; high-density polyethylene, brand ExxonMobil, grade HTA108; crosslinking agent, selected as di-tert-butyl peroxide; co-crosslinking agent, selected as triallyl isocyanurate; antioxidant, selected as antioxidant 1010; light stabilizer, selected as hindered amine light stabilizer, model GW-944; nano zinc oxide, particle size 50nm; nano aluminum oxide, particle size 30nm; silane coupling agent, model KH550; crosslinked polyethylene, brand Unica Japan, grade HFDJ-4201S. MI3, purchased from Shanghai Oushuo Plastics Co., Ltd.; UV absorber, model UV384-2, active ingredient content 95%; zinc stearate, active ingredient content 99%; aluminum hydroxide, active ingredient content 99.6%, purchased from Jinan Jiuding New Material Industry Co., Ltd.; silicon nitride, particle size 40nm; methyl methacrylate, active ingredient content 99.9%; benzoyl peroxide, active ingredient content 99%; aramid fiber, specification 3mm; glass fiber, specification 2mm.

[0039] The following are examples of the preparation of modified silicon nitride.

[0040] Preparation Example 1

[0041] The modified silicon nitride of Example 1 was prepared by the following steps:

[0042] S1. First, wash 1 kg of silicon nitride with 75% ethanol solution. Then, add 1 kg of silicon nitride to 10 L of 5% dilute hydrochloric acid solution and ultrasonically disperse for 30 min. Filter, wash until neutral, dry, add to 1 L of 10% silane coupling agent-ethanol mixed solution, stir and react at 80℃ for 2 h to obtain pretreated silicon nitride.

[0043] S2. Add 400g of methyl methacrylate to 800ml of acetone and mix well to obtain a methyl methacrylate solution.

[0044] S3. Add the pretreated silicon nitride to a methyl methacrylate solution, add 4g of benzoyl peroxide, stir for 2h under nitrogen and 70℃, precipitate, filter, wash, and vacuum dry to obtain modified silicon nitride.

[0045] Preparation Examples 2-5

[0046] The modified silicon nitride in Preparation Examples 2-5 was prepared in the same way as in Preparation Example 1, except that the amount of methyl methacrylate used was 500g, 1kg, 1.5kg and 1.6kg, respectively, while the other raw materials and dosages were the same as in Preparation Example 1.

[0047] Example 1

[0048] The steel wire reinforced core overhead insulated cable of Example 1 was prepared by the following method:

[0049] According to the dosage in Table 1, the raw materials of the insulation layer are mixed at 120℃ for 15 minutes, extruded (zone 1 temperature is 150℃, zone 2 temperature is 170℃, zone 3 temperature is 160℃), and vulcanized at 140℃ for 10 minutes to obtain the insulation layer material.

[0050] According to the dosage in Table 2, the raw materials for the sheath are mixed at 120℃ for 15 minutes, extruded (zone 1 temperature is 150℃, zone 2 temperature is 170℃, zone 3 temperature is 160℃), and vulcanized at 140℃ for 10 minutes to obtain the sheath material.

[0051] The steel wire reinforcing core is coated with an epoxy resin layer by spraying the following steps: preheating the steel wire at 200°C for 13 minutes, spraying the epoxy resin, curing at 200°C for 25 minutes, and then allowing it to cool naturally; the thickness of the epoxy resin coating is 0.15 mm, and the epoxy resin particle size is 100 mesh.

[0052] The steel wire reinforcing core is twisted in a Z-shape with several aluminum conductors to obtain the conductor core. The insulation material is extruded and wrapped around the surface of the conductor core, and then the sheath is extruded and wrapped around the surface of the insulation layer to obtain the steel wire reinforcing core overhead insulated cable.

[0053] Example 2

[0054] The difference between the steel wire reinforced core overhead insulated cable of Example 2 and Example 1 is that the steel wire reinforced core surface is coated with an epoxy resin coating. Specifically, the steel wire is degreased and deoiled, and then sandblasted with 100-mesh quartz sand at a pressure of 0.5 MPa to achieve a roughness of Ra 8 μm. The steel wire is then preheated at 200°C for 13 minutes, coated with epoxy resin, cured at 200°C for 25 minutes, and allowed to cool naturally. The thickness of the epoxy resin coating is 0.15 mm, and the epoxy resin particle size is 100 mesh. The remaining steps, as well as the types and amounts of raw materials, are the same as in Example 1.

[0055] Examples 3-6

[0056] The steel wire reinforced core overhead insulated cables of Examples 3-6 are the same as those of Example 2, except that the amount of each raw material in the insulation layer is different, as detailed in Table 1.

[0057] Table 1. Raw material dosage (kg) for insulating layers in Examples 3-6

[0058]

[0059]

[0060] Table 2. Raw material dosage (kg) for sheaths in Examples 1-6

[0061] Examples 1-2 Example 3 Example 4 Example 5 Example 6 Cross-linked polyethylene 90 90 90 90 90 antioxidants 0.8 0.8 0.8 0.8 0.8 UV absorber 0.8 0.8 0.8 0.8 0.8 Zinc stearate 1 1 1 1 1 Aluminum hydroxide 19.8 22 23.58 24.74 25.67 silicon nitride 13.2 11 9.42 8.25 7.33 Silane coupling agents 1.5 1.5 1.5 1.5 1.5

[0062] Examples 7-11

[0063] The steel wire reinforced core overhead insulated cables of Examples 7-11 are the same as those of Example 4, except that the silicon nitride in the sheath material of the steel wire reinforced core overhead insulated cables is the modified silicon nitride prepared in Examples 1-5, and the other raw materials and dosages are the same as those of Example 4.

[0064] Examples 12-16

[0065] The steel wire reinforced core overhead insulated cables of Examples 12-16 are the same as those of Example 9, except that they also include aramid fiber and glass fiber. The amounts of aramid fiber and glass fiber are 10kg and 5kg, 10kg and 10kg, 10kg and 15kg, 10kg and 20kg, and 10kg and 25kg, respectively. The types and amounts of other raw materials are the same as those of Example 9.

[0066] Comparative Example 1

[0067] The steel wire reinforced core overhead insulated cable of Comparative Example 1 is the same as that of Example 1, except that the surface of the steel wire reinforced core is not coated with epoxy resin, and the other raw materials and dosages are the same as those of Example 1.

[0068] Comparative Example 2

[0069] The steel wire reinforced core overhead insulated cable of Comparative Example 2 is the same as that of Example 1, except that silicon nitride in the sheath material is replaced with aluminum hydroxide in equal amounts, while the other raw materials and dosages are the same as those of Example 1.

[0070] Comparative Example 3

[0071] The steel wire reinforced core overhead insulated cable of Comparative Example 3 is the same as that of Example 1, except that aluminum hydroxide in the sheath material is replaced with silicon nitride in equal amounts, while the other raw materials and dosages are the same as those of Example 1.

[0072] Performance Testing (Part 1)

[0073] The performance of the overhead insulated cables obtained from different Examples 1-16 and Comparative Examples 1-3 was tested, and the test results are detailed in Table 3.

[0074] Tensile strength: According to GB / T 2951.11-2008 standard, the sheath of the overhead insulated cable is cut along the axial direction, a narrow strip is cut out and made into a small dumbbell specimen for tensile strength testing.

[0075] Elongation at break: The elongation at break of the sheath of overhead insulated cables is tested in accordance with GB / T 2951.11-2008 standard.

[0076] Tensile strength: The tensile strength of the sheath of overhead insulated cables was tested in accordance with GB / T 1040.1-2018 "Determination of tensile properties of plastics - Part 1: General".

[0077] Conductor breaking force: The conductor breaking force of the overhead insulated cable is tested in accordance with GB / T 1388-2018 "Rated voltage 1kV, 10kV steel wire reinforced core overhead insulated cable".

[0078] Table 3 Performance test results of different overhead insulated conductors

[0079]

[0080]

[0081] The test results in Table 3 show that the tensile strength, elongation at break, tensile strength and conductor breaking force of the overhead insulated cable obtained in this application can reach up to 79.2 MPa, 490%, 20.0 MPa and 80.6 kN, respectively, which improves the mechanical strength of the overhead insulated cable.

[0082] Based on the performance test data of the overhead insulated cables in Examples 1 and 2, it can be seen that the conductor breaking force of the overhead insulated cable in Example 2 is 80.6kN, which is higher than that in Example 1. This indicates that degreasing and oil removal of the steel wires before spraying the epoxy resin coating on the surface of the reinforcing core, followed by sandblasting, can further improve the conductor breaking force of the overhead insulated cable, thereby improving the mechanical strength of the overhead insulated cable.

[0083] Based on the performance test data of the overhead insulated cables in Examples 2-6, it can be seen that the tensile strength, elongation at break, and tensile strength of the overhead insulated cables in Examples 3-5 are 73.5-74.2 MPa, 473-476%, and 17.7-19.1 MPa, respectively, which are all higher than those in Examples 2 and 6. This indicates that a weight ratio of silicon nitride to aluminum hydroxide in the sheath material of 1:(2-3) is more suitable, which improves the mechanical strength of the overhead insulated cable.

[0084] Based on the performance test data of the overhead insulated cables in Examples 7-11, it can be seen that the tensile strength, elongation at break, and tensile strength of the overhead insulated cables in Examples 8-10 are 75.2-76.1 MPa, 481-484%, and 18.7-19.0 MPa, respectively, all of which are higher than those in Examples 7 and 11. This indicates that modifying silicon nitride and controlling the mass ratio of silicon nitride to methyl methacrylate to be 1:(0.5-1.5) during the modification process can improve the mechanical strength of the overhead insulated cables.

[0085] Based on the performance test data of the overhead insulated cables in Examples 12-16, it can be seen that the tensile strength, elongation at break, and tensile strength of the overhead insulated cables in Examples 13-15 are 77.5-79.2 MPa, 487-490%, and 19.5-20.0 MPa, respectively, which are all higher than those in Examples 12 and 16. This indicates that the addition of aramid fiber and glass fiber to the sheath material, with a weight ratio of 1:(1-2), is more appropriate and improves the mechanical strength of the overhead insulated cable.

[0086] In addition, based on the performance test data of the overhead insulated cables in Comparative Examples 1-3 and Example 1, it was found that spraying an epoxy resin coating on the surface of the steel wire reinforcing core of the overhead insulated cable and adding silicon nitride and aluminum hydroxide to the sheath material can improve the mechanical strength of the overhead insulated cable to varying degrees.

[0087] Performance Testing (Part 2)

[0088] The performance of the overhead insulated cables obtained from different Examples 2-16 and Comparative Examples 2-3 was tested, and the test results are detailed in Table 4.

[0089] Weather resistance: A xenon lamp aging chamber is used to simulate the natural environment, with an irradiance of 550±50W / m in the wavelength range of 300-400nm. 2 The temperature was 65℃, the air temperature inside the chamber was 50±3℃, the relative humidity was 50%±5%, and water was sprayed for 18 minutes every 102 minutes of light exposure. The tensile strength and elongation at break of the overhead insulated cable sheath were tested after 42 days, and the rate of change of tensile strength and elongation at break after 42 days were calculated.

[0090] Table 4 Performance test results of different overhead insulated conductors

[0091] 42d tensile strength change rate / % 42d elongation at break / % Example 2 18 20 Example 3 15 19 Example 4 13 18 Example 5 16 19 Example 6 17 20 Example 7 10 15 Example 8 8 13 Example 9 7 10 Example 10 8 12 Example 11 10 14 Example 12 6 8 Example 13 4 7 Example 14 3 5 Example 15 5 7 Example 16 6 8 Comparative Example 2 25 29 Comparative Example 3 23 26

[0092] The test results in Table 4 show that the overhead insulated cable obtained in this application has the lowest change rate of tensile strength and elongation at break after 42 days of weathering test, which is only 3% and 5% respectively, thus improving the weathering resistance of the overhead insulated cable.

[0093] Based on the performance test data of overhead insulated cables in Examples 2-6, it can be seen that the change rates of tensile strength and elongation at break of overhead insulated conductors in Examples 3-5 after 42 days of weathering resistance testing were 13-16% and 18-19%, respectively, which were lower than those in Examples 2 and 6. This indicates that a weight ratio of silicon nitride to aluminum hydroxide in the sheathing material of 1:(2-3) is more suitable, which improves the weather resistance of overhead insulated cables.

[0094] Based on the performance test data of the overhead insulated cables in Examples 7-11, it can be seen that the changes in tensile strength and elongation at break of the overhead insulated conductors in Examples 8-10 after 42 days of weathering resistance testing were 7-8% and 10-13%, respectively, both lower than those in Examples 7 and 11. This indicates that modifying silicon nitride and controlling the mass ratio of silicon nitride to methyl methacrylate to be 1:(0.5-1.5) during the modification process can improve the weather resistance of overhead insulated cables.

[0095] Based on the performance test data of overhead insulated cables in Examples 12-16, it can be seen that the tensile strength and elongation at break of the overhead insulated conductors in Examples 13-15 after 42 days of weather resistance testing were 3-5% and 5-7%, respectively, which were lower than those in Examples 12 and 16. This indicates that adding aramid fiber and glass fiber to the sheath material in a weight ratio of 1:(1-2) is more appropriate and improves the weather resistance of the overhead insulated cable.

[0096] In addition, based on the performance test data of the overhead insulated cables in Comparative Examples 2-3 and Example 1, it was found that adding silicon nitride and aluminum hydroxide to the sheath material of overhead insulated cables can improve the weather resistance of overhead insulated cables to varying degrees.

[0097] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An aerial insulated cable with steel wire reinforced core, characterized in that, It includes a conductor core, an insulation layer, and a sheath; the conductor core is formed by twisting a steel wire reinforcing core with several aluminum wires; the surface of the steel wire reinforcing core is coated with an epoxy resin coating; The sheath comprises the following raw materials in parts by weight: 80-100 parts cross-linked polyethylene, 0.5-1 part antioxidant, 0.5-1 part ultraviolet absorber, 0.5-1.5 parts zinc stearate, 15-30 parts aluminum hydroxide, 5-15 parts silicon nitride, 1-2 parts silane coupling agent, aramid fiber, and glass fiber. The specific method for spraying epoxy resin onto the surface of the steel wire reinforcing core is as follows: the steel wire is degreased and deoiled, and then sandblasted with quartz sand of 80-120 mesh at a sandblasting pressure of 0.4-0.6 MPa to achieve a roughness of Ra5-10 μm. The steel wire is then preheated at 180-220℃ for 10-15 minutes, epoxy resin is sprayed, and the coating is cured at 180-200℃ for 20-30 minutes, followed by natural cooling. The thickness of the sprayed epoxy resin is 0.12-0.18 mm, and the epoxy resin particle size is 80-120 mesh. The silicon nitride is prepared through modification, specifically as follows: S1. First, clean the silicon nitride with 75% ethanol solution, then add the silicon nitride to 5% dilute hydrochloric acid solution and ultrasonically disperse for 30-40 min. Filter, wash until neutral, dry, add to silane coupling agent-ethanol mixed solution, stir and react at 75-85℃ for 2-3 h to obtain pretreated silicon nitride. S2. Add methyl methacrylate to acetone and mix, stirring until homogeneous to obtain a methyl methacrylate solution; S3. Add the pretreated silicon nitride to a methyl methacrylate solution, add benzoyl peroxide, stir under nitrogen and 60-80℃ for 2-3 hours, precipitate, filter, wash, and vacuum dry to obtain modified silicon nitride.

2. Steel wire reinforced core aerial insulated cable according to claim 1, characterized in that, The weight ratio of silicon nitride to aluminum hydroxide is 1:(2-3).

3. The steel wire reinforced core overhead insulated cable according to claim 1, characterized in that: The mass ratio of silicon nitride to methyl methacrylate is 1:(0.5-1.5).

4. The steel wire reinforced core overhead insulated cable according to claim 1, characterized in that: The weight ratio of aramid fiber to glass fiber is 1:(1-2).

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