Aerial insulated cable with long service life

Abstract

The invention relates to the technical field of aerial cables, and provides a long-service-life aerial insulated cable which comprises a structural conductor, a first insulating layer, a second insulating layer and a sheath layer from inside to outside. The sheath layer comprises the following raw material components in parts by mass: 95-105 parts of nylon 66, 20-24 parts of glass fiber, 1-2 parts of an antioxidant, 0.5-2 parts of a lubricant, 0.6-1 part of a light stabilizer, 10-12 parts of a waterproof agent and 1-3 parts of a compatilizer; the first insulating layer and the second insulating layer are respectively and independently made of crosslinked polyethylene; the waterproof agent is prepared from high-density polyethylene and 5-formyl methyl salicylate. According to the technical scheme, the problem of poor waterproofness of the long-service-life overhead insulated cable caused by poor waterproofness of the sheath layer of the long-service-life overhead insulated cable in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of overhead cables, and in particular to a long-life overhead insulated cable. Background Art

[0002] In the field of modern power transmission, the advancement of smart grid construction and the growing demand for power transmission in complex environments are placing higher demands on the comprehensive performance of sheath materials for overhead insulated cables. While traditional cable materials such as polyethylene and cross-linked polyethylene (XLPE) meet insulation and transmission requirements to a certain extent, they are increasingly showing limitations in terms of mechanical strength, weather resistance, and lightweighting. These materials struggle to adapt to long-term, stable operation in extreme climates, and they also fail to fully align with the industry's trend toward higher efficiency and environmental friendliness.

[0003] As a high-performance engineering plastic, nylon 66 is an ideal alternative to traditional materials due to its excellent mechanical strength, wear resistance, and good chemical corrosion resistance. However, the polar amide groups contained in the nylon 66 molecular chain give it a strong affinity for water molecules. In long-term humid or rainy environments, the material is prone to water absorption, resulting in a decrease in insulation performance. The infiltration of water will destroy the ordered structure of the molecular chain, thereby affecting the electrical properties and mechanical stability of the material. This inherent defect restricts its widespread application in the field of overhead cables. Existing technologies often add waterproofing agents such as polyethylene and polypropylene to blend with nylon 66. However, the solubility parameters of polyolefins and polyamide resin materials differ significantly, resulting in poor compatibility between the materials. As a result, the waterproofness of the nylon sheath after adding polyolefins is still insufficient.

[0004] In this context, it is of vital importance to solve the problem of poor waterproofness of the sheath layer of long-life overhead insulated cables with nylon 66 as the main material. Summary of the Invention

[0005] The present invention provides a long-life overhead insulated cable, which solves the problem in the related art that the sheath layer of the long-life overhead insulated cable has poor waterproofness, resulting in poor waterproofness of the long-life overhead insulated cable.

[0006] The technical solutions of the present invention are as follows: The present invention provides a long-life overhead insulated cable, which comprises, from the inside out, a structural conductor, a first insulating layer, a second insulating layer, and a sheath layer; the sheath layer is made of the following components in parts by weight: 95-105 parts of nylon 66, 20-24 parts of glass fiber, 1-2 parts of an antioxidant, 0.5-2 parts of a lubricant, 0.6-1 parts of a light stabilizer, 10-12 parts of a waterproofing agent, and 1-3 parts of a compatibilizer; The materials of the first insulating layer and the second insulating layer are each independently cross-linked polyethylene; The waterproofing agent includes high-density polyethylene and 5-formylsalicylic acid methyl ester.

[0007] As a further technical solution, the structural conductor includes a stranded wire and a water-blocking tape wrapped around the surface of the stranded wire.

[0008] When glass fiber is added to the sheath layer of the high-life overhead insulated cable of the present invention, the glass fiber and nylon 66 form a composite material. The glass fiber and nylon 66 are physically entangled or interact with each other. When the sheath is subjected to external force, the glass fiber can bear most of the stress by virtue of its own high strength, limiting the deformation of the nylon 66 matrix, thereby ensuring the overall strength, hardness and tensile resistance of the sheath layer.

[0009] When an antioxidant is added to the sheath layer of the high-life overhead insulated cable of the present invention, the antioxidant can inhibit or delay the oxidative degradation of the polymer material due to factors such as heat and oxygen. Its mechanism of action is mainly to capture free radicals generated during the oxidation process of the polymer material and convert highly active free radicals into relatively stable substances, thereby interrupting the oxidation chain reaction; or decompose the hydroperoxides generated during the oxidation process and convert them into harmless products, thereby preventing further oxidation reactions.

[0010] When lubricant is added to the sheath layer of the high-life overhead insulated cable of the present invention, the lubricant can lubricate between the molecular chains of the polymer material and reduce the friction between the molecular chains, thereby making the material more fluid in a molten state and easier to process and shape.

[0011] When a light stabilizer is added to the sheath layer of the high-life overhead insulated cable of the present invention, the light stabilizer can capture free radicals generated during the photooxidation process of the polymer material, decompose hydroperoxides, and quench excited molecules, thereby inhibiting the photooxidation reaction of the polymer material caused by ultraviolet rays when the cable sheath is exposed to sunlight for a long time, and protecting the polymer material of the sheath layer from damage by ultraviolet rays.

[0012] As a further technical solution, the mass ratio of the high-density polyethylene to 5-formylsalicylic acid methyl ester is 5:2~3.

[0013] As a further technical solution, the mass ratio of the high-density polyethylene to 5-formyl methyl salicylate is 5:3.

[0014] In the sheath layer of the high-life overhead insulated cable of the present invention, the mass ratio of high-density polyethylene to 5-formylsalicylic acid methyl ester can be 5:2, 5:2.1, 5:2.2, 5:2.3, 5:2.4, 5:2.5, 5:2.6, 5:2.7, 5:2.8, 5:2.9, 5:3, preferably 5:3.

[0015] As a further technical solution, the nylon 66 includes a first nylon 66 and a second nylon 66; The relative viscosity of the first nylon 66 is 2.60-2.80 dL / g; The relative viscosity of the second nylon 66 is 2.10-2.30 dL / g.

[0016] The sheath layer of the high-life overhead insulated cable of the present invention utilizes a compound of two nylon 66 materials with different relative viscosities, thereby enhancing the tensile strength of the sheath layer. In the present invention, the relative viscosity of the nylon 66 is closely related to the length and aggregate structure of the molecular chain. The first nylon 66 has a relative viscosity of 2.60 to 2.80 dL / g. Its higher relative viscosity and longer molecular chains enable the molecular chains of the nylon 66 to synergistically resist external forces. The strong interchain forces disperse tensile stress, thereby providing the sheath layer with a higher initial tensile strength. The second nylon 66 has a relative viscosity of 2.10 to 2.30 dL / g. Its lower relative viscosity and smaller molecular chains impart a certain degree of flexibility and chain segment mobility to the material. During the stretching process, the shorter molecular chains can flexibly deform, alleviating localized stress concentration. When the rigid structure formed by the first nylon 66 is subjected to tensile force, the second nylon 66 can adaptively adjust itself internally. Through the sliding and rearrangement of the molecular chains, the stress is more evenly distributed throughout the entire material system, avoiding excessive stress concentration in certain local areas that may cause premature fracture of the material. Therefore, the first nylon 66 and the second nylon 66 synergistically improve the tensile strength of the sheath layer of the high-life overhead insulated cable.

[0017] As a further technical solution, the mass ratio of the first nylon 66 to the second nylon 66 is 5-6:1.

[0018] In the sheath layer of the high-life overhead insulated cable of the present invention, the mass ratio of the first nylon 66 to the second nylon 66 is 5:1, 5.1:1, 5.2:1, 5.3:1, 5.4:1, 5.5:1, 5.6:1, 5.7:1, 5.8:1, 5.9:1, and 6:1, preferably 6:1.

[0019] In the sheath layer of the long-life overhead insulated cable of the present invention, when the mass ratio of the first nylon 66 to the second nylon 66 is 5-6, the tensile strength of the sheath layer of the long-life overhead insulated cable is further improved.

[0020] As a further technical solution, the antioxidant includes one or more of antioxidant 1010, antioxidant 1076, and antioxidant 168.

[0021] As a further technical solution, the lubricant includes one or more of glyceryl stearate, calcium stearate, and zinc stearate.

[0022] As a further technical solution, the light stabilizer includes one or both of the light stabilizer 770 and the light stabilizer 622 .

[0023] As a further technical solution, the compatibilizer includes one or both of maleic anhydride grafted polyethylene and maleic anhydride grafted polypropylene.

[0024] The present invention also provides a method for preparing a long-life overhead insulated cable, which is used to prepare the long-life overhead insulated cable, comprising the following steps: S1. Drawing and twisting aluminum alloy rods to obtain aluminum alloy stranded wires, and wrapping a water-blocking tape around the surface of the aluminum alloy stranded wires to obtain a structural conductor; S2. sequentially providing a first insulating layer and a second insulating layer on the surface of the structural conductor; S2. After mixing the raw materials of the sheath layer, the raw materials are extruded onto the surface of the second insulating layer to obtain the long-life overhead insulated cable.

[0025] The working principle and beneficial effects of the present invention are: In the present invention, the sheath layer of the long-life overhead insulated cable is made of high-density polyethylene and 5-formyl methyl salicylate to form a waterproofing agent, thereby improving the waterproofness of the long-life overhead insulated cable. Different from the traditional high-life overhead insulated cable sheath layer that uses a blend of polyolefin and nylon to improve the waterproofness, the present invention focuses on the mechanism by which polyolefin improves the waterproofness through the hydrophobic effect of polyolefin, and the poor compatibility of polyolefin with nylon 66 leads to limited improvement in its waterproofness. The present invention uses high-density polyethylene and 5-formylsalicylic acid methyl ester to compound. 5-formylsalicylic acid methyl ester can interact with the amide group of nylon 66 in the system, occupying the site where water molecules interact with the amide group, and 5-formylsalicylic acid methyl ester has a large steric hindrance, which can hinder the entry of water molecules. After the present invention selects high-density polyethylene and 5-formylsalicylic acid methyl ester to form a waterproofing agent, 5-formylsalicylic acid methyl ester makes up for the deficiency of polyolefin in waterproofness due to its poor compatibility with nylon 66. The two work synergistically to improve the waterproofness of the high-life overhead insulated cable. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the 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.

[0027] In the following examples and comparative examples, the first nylon 66 has a relative viscosity of 2.67 dL / g and is model EP158; the second nylon 66 has a relative viscosity of 2.20 dL / g and is model EP122; the maleic anhydride grafted polyethylene is model Exxelor PE1040; the maleic anhydride grafted polypropylene is model QE867; the glass fiber has a length of 3 mm and a diameter of 20 μm; and the high-density polyethylene is model 9003.

[0028] Example 1 A long-life overhead insulated cable comprises, from the inside out, a structural conductor, a first cross-linked polyethylene insulation layer, a second cross-linked polyethylene insulation layer, and a sheath layer; the sheath layer is made of the following components in parts by mass: 105 parts of a first nylon 66, 24 parts of glass fiber, 1 part of an antioxidant 1010, 1 part of an antioxidant 1076, 1 part of glyceryl stearate, 1 part of calcium stearate, 0.5 parts of a light stabilizer 770, 0.5 parts of a light stabilizer 622, 12 parts of a waterproofing agent, 1 part of maleic anhydride grafted polyethylene, and 2 parts of maleic anhydride grafted polypropylene; The waterproofing agent includes high-density polyethylene and 5-formylsalicylic acid methyl ester in a mass ratio of 1:1.

[0029] The method for preparing a long-life overhead insulated cable comprises the following steps: S1. Draw and twist aluminum alloy rods to obtain aluminum alloy stranded wires, and wrap water-blocking tape around the surfaces of the aluminum alloy stranded wires to obtain structural conductors; S2. sequentially providing a first cross-linked polyethylene insulation layer and a second cross-linked polyethylene insulation layer on the surface of the structural conductor; S2. After mixing the raw materials of the sheath layer, the raw materials are extruded onto the surface of the second insulating layer to obtain a long-life overhead insulated cable.

[0030] Example 2 A long-life overhead insulated cable comprises, from the inside out, a structural conductor, a first cross-linked polyethylene insulation layer, a second cross-linked polyethylene insulation layer, and a sheath layer; the sheath layer is made of the following components in parts by weight: 95 parts of a first nylon 66, 20 parts of glass fiber, 1 part of an antioxidant 168, 0.5 parts of zinc stearate, 0.6 parts of a light stabilizer 622, 10 parts of a water-repellent agent, and 1 part of maleic anhydride-grafted polypropylene; The waterproofing agent includes high-density polyethylene and methyl 5-formylsalicylate in a mass ratio of 5:1.

[0031] The method for preparing a long-life overhead insulated cable comprises the following steps: S1. Draw and twist aluminum alloy rods to obtain aluminum alloy stranded wires, and wrap water-blocking tape around the surfaces of the aluminum alloy stranded wires to obtain structural conductors; S2. sequentially providing a first cross-linked polyethylene insulation layer and a second cross-linked polyethylene insulation layer on the surface of the structural conductor; S2. After mixing the raw materials of the sheath layer, the raw materials are extruded onto the surface of the second insulating layer to obtain a long-life overhead insulated cable.

[0032] Example 3 The only difference between this embodiment and embodiment 2 is that the mass ratio of high-density polyethylene to methyl 5-formylsalicylate in this embodiment is 5:4.

[0033] Example 4 The only difference between this embodiment and embodiment 2 is that the mass ratio of high-density polyethylene to methyl 5-formylsalicylate in this embodiment is 5:2.

[0034] Example 5 The only difference between this embodiment and embodiment 2 is that the mass ratio of high-density polyethylene to methyl 5-formylsalicylate in this embodiment is 5:3.

[0035] Example 6 The only difference between this embodiment and embodiment 5 is that the first nylon 66 in this embodiment is replaced by a second nylon 66 of equal mass.

[0036] Example 7 The only difference between this embodiment and embodiment 5 is that the first nylon 66 in this embodiment is replaced by mixed nylon 66 of equal mass, and the mixed nylon 66 includes the first nylon 66 and the second nylon 66 in a mass ratio of 5:1.

[0037] Example 8 The only difference between this embodiment and embodiment 5 is that the first nylon 66 in this embodiment is replaced by mixed nylon 66 of equal mass, and the mixed nylon 66 includes the first nylon 66 and the second nylon 66 in a mass ratio of 6:1.

[0038] Comparative Example 1 The only difference between this comparative example and Example 2 is that the waterproofing agent in this comparative example is high-density polyethylene.

[0039] Comparative Example 2 The only difference between this comparative example and Example 2 is that the waterproofing agent in this comparative example is methyl 5-formylsalicylate.

[0040] Comparative Example 3 The only difference between this comparative example and Example 2 is that this comparative example does not contain a waterproofing agent.

[0041] Experimental Example 1 The sheath layers of the long-life overhead insulated cables prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were tested for water absorption by mass according to the method specified in GB / T 1034-2008 "Determination of Water Absorption of Plastics", using Method 2. The test results are shown in Table 1.

[0042] Table 1 Water absorption mass fraction test results

[0043] As can be seen from Table 1, the water absorption mass fraction of the sheath layer of the long-life overhead insulated cable prepared in Examples 1 to 5 of the present invention reaches less than 1.6%. Therefore, in the present invention, a compound of high-density polyethylene and 5-formylsalicylic acid methyl ester is selected as a water reducer to improve the waterproofness of the sheath layer of the long-life overhead insulated cable.

[0044] Experimental Example 2 The sheath layers of the long-life overhead insulated cables produced in Examples 5-8 were tested for tensile strength according to the method specified in GB / T 2951.11-2008, "General test methods for insulation and sheathing materials of electrical and optical cables - Part 11: General test methods - Thickness and dimensional measurements - Mechanical properties tests." The test specimens were dumbbell specimens with a thickness of 3 mm and a test rate of 50 mm / min. The test results are shown in Table 2.

[0045] Table 2 Tensile strength test results

[0046] As can be seen from Table 2, the tensile strength of the sheath layer of the long-life overhead insulated cable prepared in Examples 7 and 8 of the present invention reaches more than 145 MPa. Therefore, the use of two nylon 66s with different relative viscosities in the present invention improves the tensile strength of the sheath layer of the long-life overhead insulated cable.

[0047] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A long-life overhead insulated cable, characterized in that: From the inside to the outside, it includes a structural conductor, a first insulating layer, a second insulating layer, and a sheath layer; the raw materials of the sheath layer include the following components by weight: 95-105 parts of nylon 66, 20-24 parts of glass fiber, 1-2 parts of antioxidant, 0.5-2 parts of lubricant, 0.6-1 parts of light stabilizer, 10-12 parts of waterproofing agent, and 1-3 parts of compatibilizer; The materials of the first insulating layer and the second insulating layer are each independently cross-linked polyethylene; The waterproofing agent includes high-density polyethylene and 5-formylsalicylic acid methyl ester.

2. A long-life overhead insulated cable according to claim 1, characterized in that: The structural conductor includes a stranded wire and a water-blocking tape wrapped around the surface of the stranded wire.

3. The long-life overhead insulated cable according to claim 1, characterized in that: The mass ratio of the high-density polyethylene to 5-formyl methyl salicylate is 5:2-3.

4. A long-life overhead insulated cable according to claim 3, characterized in that: The mass ratio of the high-density polyethylene to 5-formyl methyl salicylate is 5:

3.

5. A long-life overhead insulated cable according to any one of claims 1 to 4, characterized in that: The nylon 66 includes a first nylon 66 and a second nylon 66; The relative viscosity of the first nylon 66 is 2.60-2.80 dL / g; The relative viscosity of the second nylon 66 is 2.10-2.30 dL / g.

6. A long-life overhead insulated cable according to claim 5, characterized in that: The mass ratio of the first nylon 66 to the second nylon 66 is 5-6:

1.

7. The long-life overhead insulated cable according to claim 1, characterized in that: The antioxidant includes one or more of antioxidant 1010 , antioxidant 1076 , and antioxidant 168 .

8. The long-life overhead insulated cable according to claim 1, characterized in that: The lubricant includes one or more of glyceryl stearate, calcium stearate, and zinc stearate.

9. The long-life overhead insulated cable according to claim 1, characterized in that: The light stabilizer includes one or both of the light stabilizer 770 and the light stabilizer 622 .

10. The long-life overhead insulated cable according to claim 1, characterized in that: The compatibilizer includes one or both of maleic anhydride grafted polyethylene and maleic anhydride grafted polypropylene.

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