A cross-linked polyethylene insulated overhead cable and its preparation method

Abstract

This invention relates to the field of cable technology and proposes a cross-linked polyethylene (XLPE) insulated overhead cable and its preparation method. The XLPE insulated overhead cable comprises, from the inside out, a conductor, a shielding layer, and an insulation layer. The conductor comprises, from the inside out, a center conductor, an inner core layer, and an outer core layer. The inner core layer consists of 6 conductors, and the outer core layer consists of 12 conductors. The insulation layer comprises the following components by weight: 60-80 parts polyethylene resin, 10-20 parts vinyl elastomer, 0.8-1.5 parts cross-linking agent, 10-20 parts flame retardant, 1-3 parts antioxidant, 1-2 parts lubricant, 10-20 parts filler, and 1-3 parts compatibilizer. The flame retardant comprises the following raw materials: tetraethyl orthosilicate, Triton, and aminotrimethylenephosphonic acid. The XLPE insulated overhead cable provided by this invention has excellent flame retardant properties, solving the technical problem of insufficient flame retardancy in existing cable insulation layers.

Description

Technical Field

[0001] This invention relates to the field of cable technology, specifically to a cross-linked polyethylene insulated overhead cable and its preparation method. Background Technology

[0002] Cross-linked polyethylene (XLPE) insulated overhead cables, with their excellent electrical insulation, heat aging resistance, and mechanical properties, have been widely used in urban power grid renovation, rural power grid extension, and various overhead transmission projects. However, with the continuous growth of power load and the increasing complexity of the line laying environment, cables are highly susceptible to fires caused by lightning overvoltage, line short circuits, or external fire sources during operation. Once the insulation layer is ignited, the fire will spread rapidly along the line, causing not only prolonged power outages and equipment damage, but also the potential to ignite surrounding vegetation or structures, thus posing safety hazards and property damage risks. Therefore, there is an urgent need to develop a cross-linked polyethylene (XLPE) insulated overhead cable with excellent flame-retardant properties. Summary of the Invention

[0003] To address the above technical problems, this invention provides a cross-linked polyethylene insulated overhead cable and its preparation method. The insulation material of the cross-linked polyethylene insulated overhead cable provided by this invention has excellent flame retardant properties, solving the technical problem of insufficient flame retardancy of existing cable insulation layers.

[0004] The specific technical solution of the present invention is as follows: According to one aspect of the present invention, a cross-linked polyethylene insulated overhead cable is provided, comprising, from the inside out, a conductor, a shielding layer, and an insulation layer; the conductor comprises, from the inside out, a center conductor, an inner core layer, and an outer core layer; the inner core layer consists of 6 conductors; and the outer core layer consists of 12 conductors. The raw materials of the insulation layer include the following components by weight: 60-80 parts of polyethylene resin, 10-20 parts of ethylene-1-octene copolymer, 0.8-1.5 parts of crosslinking agent, 10-20 parts of flame retardant, 1-3 parts of antioxidant, 1-2 parts of lubricant, 10-20 parts of filler, and 1-3 parts of compatibilizer; The flame retardant includes the following raw materials: tetraethyl orthosilicate, Triton, and aminotrimethylenephosphonic acid.

[0005] In the above technical solution, the conductor is one of aluminum alloy conductor, pure aluminum conductor, or magnesium-aluminum alloy conductor.

[0006] In the above technical solution, the shielding layer is a metal shielding layer.

[0007] In the above technical solution, the preparation method of the flame retardant includes the following steps: A1. After adding tetraethyl orthosilicate to solvent I and mixing evenly, ammonia water is added to obtain premix solution I; A2. Add aminotrimethylenephosphonic acid to solvent II and mix thoroughly to obtain premixed solution II; A3. After mixing Triton into solvent III and mixing thoroughly, add premixed solution II and mix to obtain premixed solution III; A4. Add premixed liquid III to premixed liquid I and mix, then freeze-dry to obtain the flame retardant.

[0008] In the above technical solution, the crosslinking agent includes one or more of dicumyl peroxide, di-tert-butyldicumyl peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0009] In the above technical solution, the antioxidant includes one or more of antioxidant 1010, antioxidant 168, and antioxidant 1076.

[0010] In the above technical solution, the lubricant includes one or more of zinc stearate, calcium stearate, and polyethylene wax.

[0011] In the above technical solution, the filler includes vermiculite, boehmite and zirconium phosphate.

[0012] In the above technical solution, the mass ratio of vermiculite, boehmite and zirconium phosphate is 5:3:1~3.

[0013] According to another aspect of the present invention, the present invention also provides a method for preparing the above-mentioned cross-linked polyethylene insulated overhead cable, comprising the following steps: S1. Twist 6 wires together outside the center wire to form the inner core layer; twist 12 wires together outside the inner core layer to form the conductor; S2. Wrap the shielding material around the outside of the conductor to form a shielding layer; S3. Extrude the insulation material onto the outside of the insulation layer and crosslink it to obtain the crosslinked polyethylene insulated overhead cable.

[0014] Compared with existing technologies, this invention provides a cross-linked polyethylene insulated overhead cable and its preparation method. By adding tetraethyl orthosilicate, Triton, and aminotrimethylene phosphonic acid as flame retardant raw materials, aminotrimethylene phosphonic acid composite silica is obtained, thereby improving the flame retardancy of the insulation layer. Aminotrimethylene phosphonic acid, when heated, releases phosphorus-containing free radical scavengers and nitrogen-containing inert gases, exerting a synergistic flame-retardant effect in both the gas and condensed phases. Silica, through its physical barrier effect, delays the thermal decomposition of the matrix. The synergistic effect of aminotrimethylene phosphonic acid in capturing combustion free radicals and diluting combustible gases in the gas phase, and promoting char formation in the condensed phase, combined with the physical thermal and oxygen barrier properties of silica, achieves multiple synergistic effects of gas and condensed phases, chemical inhibition, and physical barrier, effectively improving the flame-retardant performance of the cross-linked polyethylene insulated overhead cable insulation layer. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention more apparent, the invention is described in detail below. It should be understood that the invention is not limited to the description herein.

[0016] Polyethylene resin The polyethylene resin used in this invention is a polyethylene resin known in the art that can be used in cables. In the cross-linked polyethylene insulated overhead cable of this invention, the role of the polyethylene resin is to provide excellent electrical insulation and basic mechanical properties, block current conduction to ensure the safety of cable use, and at the same time, it has good processing fluidity, providing a stable dispersion carrier for other components in the insulation layer, ensuring the overall stability of the insulation layer performance.

[0017] Ethylene-1-octene copolymer The ethylene-1-octene copolymer used in this invention is an ethylene-1-octene copolymer known in the art that can be used in cables. In the cross-linked polyethylene insulated overhead cable of this invention, the role of the ethylene-1-octene copolymer is to have excellent flexibility and crack resistance, which can improve the toughness of the insulation layer and reduce the risk of cracks in the insulation layer under overhead laying, alternating hot and cold conditions or external forces.

[0018] Crosslinking agent The crosslinking agent used in this invention is a known crosslinking agent for cables, and the invention is not limited to the crosslinking agents listed below. As an example, the crosslinking agent may be dicumyl peroxide, di-tert-butyldicumyl peroxide, or 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane. In the crosslinked polyethylene insulated overhead cable of this invention, the crosslinking agent initiates a crosslinking reaction of the polyethylene resin and other components in the insulation layer, forming a three-dimensional network structure. This improves the heat resistance, mechanical strength, and structural stability of the insulation layer, enhances its anti-aging properties and service life, and ensures the insulation reliability of the cable during long-term use.

[0019] antioxidants The antioxidants used in this invention are known in the art and can be used in cables, and this invention is not limited to the antioxidants listed below. For example, antioxidants may be antioxidant 1010, antioxidant 168, or antioxidant 1076. In the cross-linked polyethylene insulated overhead cable of this invention, the antioxidants inhibit the thermo-oxidative aging reaction of polyethylene and ethylene-1-octene copolymer during processing and use, capture free radicals generated by oxidation, thereby delaying the aging and degradation of the insulation material and improving the long-term thermal stability and service life of the cable in an overhead environment.

[0020] lubricant The lubricant used in this invention is a known lubricant for use in cables, and this invention is not limited to the lubricants listed below. For example, the lubricant may be zinc stearate, calcium stearate, or polyethylene wax. In the cross-linked polyethylene insulated overhead cable of this invention, the lubricant serves to reduce the friction of the insulation material during the extrusion process, improve the processing flowability of the material, and reduce adhesion between materials and between the material and the processing equipment. This avoids problems such as sticking to the mold and uneven molding during processing, ensuring the appearance quality and structural uniformity of the insulation layer.

[0021] compatibilizer The compatibilizer used in this invention is a known compatibilizer for use in cables, and this invention is not limited to the compatibilizers listed below. As examples, the compatibilizer may be maleic anhydride-grafted polyethylene, maleic anhydride-grafted ethylene-octene copolymer, or ethylene-vinyl acetate copolymer. In the cross-linked polyethylene insulated overhead cable of this invention, the compatibilizer functions to improve the compatibility between the components in the insulation layer, promote uniform dispersion of the raw materials, reduce phase separation, enhance the bonding force between the components, and ensure the overall structural stability of the insulation layer.

[0022] Cross-linked polyethylene insulated overhead cable The cross-linked polyethylene insulated overhead cable of the present invention comprises, from the inside out, a conductor, a shielding layer, and an insulation layer; the conductor comprises, from the inside out, a center conductor, an inner core layer, and an outer core layer; the inner core layer consists of 6 conductors; and the outer core layer consists of 12 conductors. The raw materials for the insulation layer include the following components by weight: 60-80 parts of polyethylene resin, 10-20 parts of ethylene-1-octene copolymer, 0.8-1.5 parts of crosslinking agent, 10-20 parts of flame retardant, 1-3 parts of antioxidant, 1-2 parts of lubricant, 10-20 parts of filler, and 1-3 parts of compatibilizer; Flame retardants include the following raw materials: tetraethyl orthosilicate, triaton, and aminotrimethylenephosphonic acid.

[0023] In cross-linked polyethylene insulated overhead cables, the polyethylene resin in the insulation layer comprises 60 to 80 parts by weight, preferably 65 to 75 parts, more preferably 65 to 70 parts, and most preferably 68 to 70 parts.

[0024] In cross-linked polyethylene insulated overhead cables, the ethylene-1-octene copolymer in the insulation layer is 10 to 20 parts by weight, preferably 12 to 20 parts, more preferably 12 to 18 parts, and most preferably 14 to 16 parts.

[0025] In cross-linked polyethylene insulated overhead cables, the cross-linking agent in the insulation layer is 0.8 to 1.5 parts by weight, preferably 1.0 to 1.5 parts, and more preferably 1.2 to 1.4 parts.

[0026] In cross-linked polyethylene insulated overhead cables, the flame retardant in the insulation layer is 10 to 20 parts by weight, preferably 12 to 20 parts, more preferably 12 to 18 parts, and most preferably 15 to 17 parts.

[0027] In cross-linked polyethylene insulated overhead cables, the antioxidant in the insulation layer is 1 to 3 parts by weight, preferably 1.5 to 3 parts, and more preferably 1.5 to 2 parts.

[0028] In cross-linked polyethylene insulated overhead cables, the lubricant in the insulation layer is 1 to 2 parts by weight, preferably 1.2 to 2 parts, and more preferably 1.5 to 1.8 parts.

[0029] In cross-linked polyethylene insulated overhead cables, the filler in the insulation layer is 10 to 20 parts by weight, preferably 12 to 18 parts, and more preferably 14 to 15 parts.

[0030] In cross-linked polyethylene insulated overhead cables, the compatibilizer in the insulation layer is 1 to 3 parts by weight, preferably 1.5 to 3 parts, and more preferably 1.5 to 2 parts.

[0031] In cross-linked polyethylene insulated overhead cables, the polyethylene resin in the insulation layer comprises 60 to 80 parts by weight, preferably 65 to 75 parts, more preferably 65 to 70 parts, and most preferably 68 to 70 parts.

[0032] In cross-linked polyethylene insulated overhead cables, the mass ratio of tetraethyl orthosilicate, aminotrimethylenephosphonic acid, and trilateraton in the insulation layer is 8:10:0.2~0.4, preferably 8:10:0.25~0.4, more preferably 8:10:0.25~0.35, and most preferably 8:10:0.25~0.3.

[0033] In cross-linked polyethylene insulated overhead cables, the fillers in the insulation layer include vermiculite, boehmite, and zirconium phosphate.

[0034] This invention improves the tensile strength of the insulation layer by adding vermiculite, boehmite, and zirconium phosphate as fillers. The reasons are as follows: vermiculite can effectively hinder the relative slippage of polymer chains, thereby enhancing the tensile strength of the matrix; boehmite acts as a bridge and pinning agent, dispersing and transferring stress and inhibiting the propagation of microcracks; zirconium phosphate not only improves the uniformity of filler dispersion, but also dissipates energy through friction between layers, enhancing the toughness and strength of the material; the three form a multidimensional synergistic reinforcing network of sheet-like, fibrous, and layered structures. The sheet-like vermiculite provides basic skeletal support, the needle-like structure of boehmite provides interpenetration and anchoring, and the layered structure of zirconium phosphate further fills the voids and optimizes the interfacial bonding. The three work together to improve the overall tensile strength of the insulation layer.

[0035] In cross-linked polyethylene insulated overhead cables, the mass ratio of vermiculite, boehmite and zirconium phosphate in the insulation layer is 5:3:1~3, preferably 5:3:1.5~3, more preferably 5:3:1.5~2, and most preferably 5:3:1.5~1.7.

[0036] Preparation method of flame retardant The present invention also provides a method for preparing the flame retardant as described above, comprising: A1. After adding tetraethyl orthosilicate to solvent I and mixing evenly, ammonia water is added to obtain premix solution I; A2. Add aminotrimethylenephosphonic acid to solvent II and mix thoroughly to obtain premixed solution II; A3. After mixing Triton into solvent III and mixing thoroughly, add premixed solution II and mix to obtain premixed solution III; A4. Add premixed liquid III to premixed liquid I and mix, then freeze-dry to obtain flame retardant.

[0037] Preparation method of cross-linked polyethylene insulated overhead cable This invention also provides a method for preparing the cross-linked polyethylene insulated overhead cable as described above, comprising the following steps: S1. Twist 6 wires together outside the center wire to form the inner core layer; twist 12 wires together outside the inner core layer to form the conductor; S2. Wrap the shielding material around the outside of the conductor to form a shielding layer; S3. Extrude the insulation material onto the outside of the insulation layer and crosslink it to obtain a crosslinked polyethylene insulated overhead cable.

[0038] To further illustrate the present invention, detailed descriptions will be provided below through the following embodiments. The raw materials used in the following embodiments and comparative examples of the present invention are all commercially available products, including: polyethylene (model: 8008H); ethylene-1-octene copolymer (model: 5061); vermiculite (average particle size: 5µm); boehmite (average particle size: 2µm); zirconium phosphate (average particle size: 1µm); silica (average particle size: 1µm); and maleic anhydride-grafted polyethylene (grafting rate: 0.8%~1.2%).

[0039] Example 1 Six aluminum alloy conductors are twisted together on the outside of the aluminum alloy center conductor to form an inner core layer; twelve aluminum alloy conductors are twisted together on the outside of the inner core layer to form a conductor; a metal shielding layer material is wrapped around the outside of the conductor to form a shielding layer; 60 parts of polyethylene resin, 10 parts of ethylene-1-octene copolymer, 0.8 parts of dicumyl peroxide, 10 parts of flame retardant, 1 part of antioxidant 1010, 1 part of zinc stearate, 10 parts of vermiculite, and 1 part of maleic anhydride grafted polyethylene are mixed and extruded onto the outside of the insulation layer and crosslinked to obtain a crosslinked polyethylene insulated overhead cable; The preparation method of the flame retardant includes the following steps: Tetraethyl orthosilicate is added to solvent I (solvent I is composed of anhydrous ethanol and water in a mass ratio of 5:2, and the mass-volume ratio of tetraethyl orthosilicate to solvent I is 1g:15mL), mixed evenly, and then ammonia water (the mass-volume ratio of tetraethyl orthosilicate to ammonia water is 1g:0.1mL) is added and mixed for 12h to obtain premix I; aminotrimethylenephosphonic acid is added to water (the mass-volume ratio of aminotrimethylenephosphonic acid to water is 1g:10mL), mixed evenly to obtain premix II; Triton is added to anhydrous ethanol (the mass-volume ratio of Triton to anhydrous ethanol is 1g:10mL), mixed evenly, and then added to premix II and mixed for 5min to obtain premix III; premix III is added to premix I and mixed for 8h, and then freeze-dried to obtain the flame retardant, wherein the mass ratio of tetraethyl orthosilicate, aminotrimethylenephosphonic acid, and Triton is 8:10:0.2.

[0040] Example 2 Six aluminum alloy conductors are twisted together on the outside of the aluminum alloy center conductor to form an inner core layer; twelve aluminum alloy conductors are twisted together on the outside of the inner core layer to form a conductor; a metal shielding layer material is wrapped around the outside of the conductor to form a shielding layer; 70 parts of polyethylene resin, 15 parts of ethylene-1-octene copolymer, 1.2 parts of dicumyl peroxide, 15 parts of flame retardant, 2 parts of antioxidant 1010, 1.5 parts of zinc stearate, 15 parts of vermiculite, and 2 parts of maleic anhydride grafted polyethylene are mixed and extruded onto the outside of the insulation layer and crosslinked to obtain a crosslinked polyethylene insulated overhead cable; The preparation method of the flame retardant includes the following steps: Tetraethyl orthosilicate is added to solvent I (solvent I is composed of anhydrous ethanol and water in a mass ratio of 5:2, and the mass-volume ratio of tetraethyl orthosilicate to solvent I is 1g:15mL), mixed evenly, and then ammonia water (the mass-volume ratio of tetraethyl orthosilicate to ammonia water is 1g:0.1mL) is added and mixed for 12h to obtain premix I; aminotrimethylenephosphonic acid is added to water (the mass-volume ratio of aminotrimethylenephosphonic acid to water is 1g:10mL), mixed evenly to obtain premix II; Triton is added to anhydrous ethanol (the mass-volume ratio of Triton to anhydrous ethanol is 1g:10mL), mixed evenly, and then added to premix II and mixed for 5min to obtain premix III; premix III is added to premix I and mixed for 8h, and then freeze-dried to obtain the flame retardant, wherein the mass ratio of tetraethyl orthosilicate, aminotrimethylenephosphonic acid, and Triton is 8:10:0.2.

[0041] Example 3 Six aluminum alloy conductors are twisted together on the outside of the aluminum alloy center conductor to form an inner core layer; twelve aluminum alloy conductors are twisted together on the outside of the inner core layer to form a conductor; a metal shielding layer material is wrapped around the outside of the conductor to form a shielding layer; 80 parts of polyethylene resin, 20 parts of ethylene-1-octene copolymer, 1.5 parts of dicumyl peroxide, 20 parts of flame retardant, 3 parts of antioxidant 1010, 2 parts of zinc stearate, 20 parts of vermiculite, and 3 parts of maleic anhydride grafted polyethylene are mixed and extruded onto the outside of the insulation layer and crosslinked to obtain a crosslinked polyethylene insulated overhead cable. The preparation method of the flame retardant includes the following steps: Tetraethyl orthosilicate is added to solvent I (solvent I is composed of anhydrous ethanol and water in a mass ratio of 5:2, and the mass-volume ratio of tetraethyl orthosilicate to solvent I is 1g:15mL), mixed evenly, and then ammonia water (the mass-volume ratio of tetraethyl orthosilicate to ammonia water is 1g:0.1mL) is added and mixed for 12h to obtain premix I; aminotrimethylenephosphonic acid is added to water (the mass-volume ratio of aminotrimethylenephosphonic acid to water is 1g:10mL), mixed evenly to obtain premix II; Triton is added to anhydrous ethanol (the mass-volume ratio of Triton to anhydrous ethanol is 1g:10mL), mixed evenly, and then added to premix II and mixed for 5min to obtain premix III; premix III is added to premix I and mixed for 8h, and then freeze-dried to obtain the flame retardant, wherein the mass ratio of tetraethyl orthosilicate, aminotrimethylenephosphonic acid, and Triton is 8:10:0.2.

[0042] Example 4 Six aluminum alloy conductors are twisted together on the outside of the aluminum alloy center conductor to form an inner core layer; twelve aluminum alloy conductors are twisted together on the outside of the inner core layer to form a conductor; a metal shielding layer material is wrapped around the outside of the conductor to form a shielding layer; 70 parts of polyethylene resin, 15 parts of ethylene-1-octene copolymer, 1.2 parts of dicumyl peroxide, 15 parts of flame retardant, 2 parts of antioxidant 1010, 1.5 parts of zinc stearate, 15 parts of vermiculite, and 2 parts of maleic anhydride grafted polyethylene are mixed and extruded onto the outside of the insulation layer and crosslinked to obtain a crosslinked polyethylene insulated overhead cable; The preparation method of the flame retardant includes the following steps: Tetraethyl orthosilicate is added to solvent I (solvent I is composed of anhydrous ethanol and water in a mass ratio of 5:2, and the mass-volume ratio of tetraethyl orthosilicate to solvent I is 1g:15mL), mixed evenly, and then ammonia water (the mass-volume ratio of tetraethyl orthosilicate to ammonia water is 1g:0.1mL) is added and mixed for 12h to obtain premix I; aminotrimethylenephosphonic acid is added to water (the mass-volume ratio of aminotrimethylenephosphonic acid to water is 1g:10mL), mixed evenly to obtain premix II; Triton is added to anhydrous ethanol (the mass-volume ratio of Triton to anhydrous ethanol is 1g:10mL), mixed evenly, and then added to premix II and mixed for 5min to obtain premix III; premix III is added to premix I and mixed for 8h, and then freeze-dried to obtain the flame retardant, wherein the mass ratio of tetraethyl orthosilicate, aminotrimethylenephosphonic acid, and Triton is 8:10:0.3.

[0043] Example 5 Six aluminum alloy conductors are twisted together on the outside of the aluminum alloy center conductor to form an inner core layer; twelve aluminum alloy conductors are twisted together on the outside of the inner core layer to form a conductor; a metal shielding layer material is wrapped around the outside of the conductor to form a shielding layer; 70 parts of polyethylene resin, 15 parts of ethylene-1-octene copolymer, 1.2 parts of dicumyl peroxide, 15 parts of flame retardant, 2 parts of antioxidant 1010, 1.5 parts of zinc stearate, 15 parts of vermiculite, and 2 parts of maleic anhydride grafted polyethylene are mixed and extruded onto the outside of the insulation layer and crosslinked to obtain a crosslinked polyethylene insulated overhead cable; The preparation method of the flame retardant includes the following steps: Tetraethyl orthosilicate is added to solvent I (solvent I is composed of anhydrous ethanol and water in a mass ratio of 5:2, and the mass-volume ratio of tetraethyl orthosilicate to solvent I is 1g:15mL), mixed evenly, and then ammonia water (the mass-volume ratio of tetraethyl orthosilicate to ammonia water is 1g:0.1mL) is added and mixed for 12h to obtain premix I; aminotrimethylenephosphonic acid is added to water (the mass-volume ratio of aminotrimethylenephosphonic acid to water is 1g:10mL), mixed evenly to obtain premix II; Triton is added to anhydrous ethanol (the mass-volume ratio of Triton to anhydrous ethanol is 1g:10mL), mixed evenly, and then added to premix II and mixed for 5min to obtain premix III; premix III is added to premix I and mixed for 8h, and then freeze-dried to obtain the flame retardant, wherein the mass ratio of tetraethyl orthosilicate, aminotrimethylenephosphonic acid, and Triton is 8:10:0.4.

[0044] Example 6 Six aluminum alloy conductors are twisted together on the outside of the aluminum alloy center conductor to form an inner core layer; twelve aluminum alloy conductors are twisted together on the outside of the inner core layer to form a conductor; a metal shielding layer material is wrapped around the outside of the conductor to form a shielding layer; 70 parts of polyethylene resin, 15 parts of ethylene-1-octene copolymer, 1.2 parts of dicumyl peroxide, 15 parts of flame retardant, 2 parts of antioxidant 1010, 1.5 parts of zinc stearate, 15 parts of filler, and 2 parts of maleic anhydride grafted polyethylene are mixed and extruded onto the outside of the insulation layer and cross-linked to obtain a cross-linked polyethylene insulated overhead cable. The filler is composed of vermiculite, boehmite, and zirconium phosphate in a mass ratio of 5:3:1. The preparation method of the flame retardant includes the following steps: Tetraethyl orthosilicate is added to solvent I (solvent I is composed of anhydrous ethanol and water in a mass ratio of 5:2, and the mass-volume ratio of tetraethyl orthosilicate to solvent I is 1g:15mL), mixed evenly, and then ammonia water (the mass-volume ratio of tetraethyl orthosilicate to ammonia water is 1g:0.1mL) is added and mixed for 12h to obtain premix I; aminotrimethylenephosphonic acid is added to water (the mass-volume ratio of aminotrimethylenephosphonic acid to water is 1g:10mL), mixed evenly to obtain premix II; Triton is added to anhydrous ethanol (the mass-volume ratio of Triton to anhydrous ethanol is 1g:10mL), mixed evenly, and then added to premix II and mixed for 5min to obtain premix III; premix III is added to premix I and mixed for 8h, and then freeze-dried to obtain the flame retardant, wherein the mass ratio of tetraethyl orthosilicate, aminotrimethylenephosphonic acid, and Triton is 8:10:0.2.

[0045] Example 7 Six aluminum alloy conductors are twisted together on the outside of the aluminum alloy center conductor to form an inner core layer; twelve aluminum alloy conductors are twisted together on the outside of the inner core layer to form a conductor; a metal shielding layer material is wrapped around the outside of the conductor to form a shielding layer; 70 parts of polyethylene resin, 15 parts of ethylene-1-octene copolymer, 1.2 parts of dicumyl peroxide, 15 parts of flame retardant, 2 parts of antioxidant 1010, 1.5 parts of zinc stearate, 15 parts of filler, and 2 parts of maleic anhydride grafted polyethylene are mixed and extruded onto the outside of the insulation layer and cross-linked to obtain a cross-linked polyethylene insulated overhead cable. The filler is composed of vermiculite, boehmite, and zirconium phosphate in a mass ratio of 5:3:2. The preparation method of the flame retardant includes the following steps: Tetraethyl orthosilicate is added to solvent I (solvent I is composed of anhydrous ethanol and water in a mass ratio of 5:2, and the mass-volume ratio of tetraethyl orthosilicate to solvent I is 1g:15mL), mixed evenly, and then ammonia water (the mass-volume ratio of tetraethyl orthosilicate to ammonia water is 1g:0.1mL) is added and mixed for 12h to obtain premix I; aminotrimethylenephosphonic acid is added to water (the mass-volume ratio of aminotrimethylenephosphonic acid to water is 1g:10mL), mixed evenly to obtain premix II; Triton is added to anhydrous ethanol (the mass-volume ratio of Triton to anhydrous ethanol is 1g:10mL), mixed evenly, and then added to premix II and mixed for 5min to obtain premix III; premix III is added to premix I and mixed for 8h, and then freeze-dried to obtain the flame retardant, wherein the mass ratio of tetraethyl orthosilicate, aminotrimethylenephosphonic acid, and Triton is 8:10:0.2.

[0046] Example 8 Six aluminum alloy conductors are twisted together on the outside of the aluminum alloy center conductor to form an inner core layer; twelve aluminum alloy conductors are twisted together on the outside of the inner core layer to form a conductor; a metal shielding layer material is wrapped around the outside of the conductor to form a shielding layer; 70 parts of polyethylene resin, 15 parts of ethylene-1-octene copolymer, 1.2 parts of dicumyl peroxide, 15 parts of flame retardant, 2 parts of antioxidant 1010, 1.5 parts of zinc stearate, 15 parts of filler, and 2 parts of maleic anhydride grafted polyethylene are mixed and extruded onto the outside of the insulation layer and cross-linked to obtain a cross-linked polyethylene insulated overhead cable. The filler is composed of vermiculite, boehmite, and zirconium phosphate in a mass ratio of 5:3:3. The preparation method of the flame retardant includes the following steps: Tetraethyl orthosilicate is added to solvent I (solvent I is composed of anhydrous ethanol and water in a mass ratio of 5:2, and the mass-volume ratio of tetraethyl orthosilicate to solvent I is 1g:15mL), mixed evenly, and then ammonia water (the mass-volume ratio of tetraethyl orthosilicate to ammonia water is 1g:0.1mL) is added and mixed for 12h to obtain premix I; aminotrimethylenephosphonic acid is added to water (the mass-volume ratio of aminotrimethylenephosphonic acid to water is 1g:10mL), mixed evenly to obtain premix II; Triton is added to anhydrous ethanol (the mass-volume ratio of Triton to anhydrous ethanol is 1g:10mL), mixed evenly, and then added to premix II and mixed for 5min to obtain premix III; premix III is added to premix I and mixed for 8h, and then freeze-dried to obtain the flame retardant, wherein the mass ratio of tetraethyl orthosilicate, aminotrimethylenephosphonic acid, and Triton is 8:10:0.2.

[0047] Example 9 Six aluminum alloy conductors are twisted together on the outside of the aluminum alloy center conductor to form an inner core layer; twelve aluminum alloy conductors are twisted together on the outside of the inner core layer to form a conductor; a metal shielding layer material is wrapped around the outside of the conductor to form a shielding layer; 70 parts of polyethylene resin, 15 parts of ethylene-1-octene copolymer, 1.2 parts of dicumyl peroxide, 15 parts of flame retardant, 2 parts of antioxidant 1010, 1.5 parts of zinc stearate, 15 parts of boehmite, and 2 parts of maleic anhydride grafted polyethylene are mixed and extruded onto the outside of the insulation layer and cross-linked to obtain a cross-linked polyethylene insulated overhead cable. The preparation method of the flame retardant includes the following steps: Tetraethyl orthosilicate is added to solvent I (solvent I is composed of anhydrous ethanol and water in a mass ratio of 5:2, and the mass-volume ratio of tetraethyl orthosilicate to solvent I is 1g:15mL), mixed evenly, and then ammonia water (the mass-volume ratio of tetraethyl orthosilicate to ammonia water is 1g:0.1mL) is added and mixed for 12h to obtain premix I; aminotrimethylenephosphonic acid is added to water (the mass-volume ratio of aminotrimethylenephosphonic acid to water is 1g:10mL), mixed evenly to obtain premix II; Triton is added to anhydrous ethanol (the mass-volume ratio of Triton to anhydrous ethanol is 1g:10mL), mixed evenly, and then added to premix II and mixed for 5min to obtain premix III; premix III is added to premix I and mixed for 8h, and then freeze-dried to obtain the flame retardant, wherein the mass ratio of tetraethyl orthosilicate, aminotrimethylenephosphonic acid, and Triton is 8:10:0.2.

[0048] Example 10 Six aluminum alloy conductors are twisted together on the outside of the aluminum alloy center conductor to form an inner core layer; twelve aluminum alloy conductors are twisted together on the outside of the inner core layer to form a conductor; a metal shielding layer material is wrapped around the outside of the conductor to form a shielding layer; 70 parts of polyethylene resin, 15 parts of ethylene-1-octene copolymer, 1.2 parts of dicumyl peroxide, 15 parts of flame retardant, 2 parts of antioxidant 1010, 1.5 parts of zinc stearate, 15 parts of zirconium phosphate, and 2 parts of maleic anhydride-grafted polyethylene are mixed and extruded onto the outside of the insulation layer and crosslinked to obtain a crosslinked polyethylene insulated overhead cable. The preparation method of the flame retardant includes the following steps: Tetraethyl orthosilicate is added to solvent I (solvent I is composed of anhydrous ethanol and water in a mass ratio of 5:2, and the mass-volume ratio of tetraethyl orthosilicate to solvent I is 1g:15mL), mixed evenly, and then ammonia water (the mass-volume ratio of tetraethyl orthosilicate to ammonia water is 1g:0.1mL) is added and mixed for 12h to obtain premix I; aminotrimethylenephosphonic acid is added to water (the mass-volume ratio of aminotrimethylenephosphonic acid to water is 1g:10mL), mixed evenly to obtain premix II; Triton is added to anhydrous ethanol (the mass-volume ratio of Triton to anhydrous ethanol is 1g:10mL), mixed evenly, and then added to premix II and mixed for 5min to obtain premix III; premix III is added to premix I and mixed for 8h, and then freeze-dried to obtain the flame retardant, wherein the mass ratio of tetraethyl orthosilicate, aminotrimethylenephosphonic acid, and Triton is 8:10:0.2.

[0049] Comparative Example 1 Six aluminum alloy conductors are twisted together on the outside of the aluminum alloy center conductor to form an inner core layer; twelve aluminum alloy conductors are twisted together on the outside of the inner core layer to form a conductor; a metal shielding layer material is wrapped around the outside of the conductor to form a shielding layer; 70 parts of polyethylene resin, 15 parts of ethylene-1-octene copolymer, 1.2 parts of dicumyl peroxide, 15 parts of flame retardant, 2 parts of antioxidant 1010, 1.5 parts of zinc stearate, 15 parts of vermiculite, and 2 parts of maleic anhydride-grafted polyethylene are mixed and extruded onto the outside of the insulation layer and cross-linked to obtain a cross-linked polyethylene insulated overhead cable; the flame retardant is composed of silicon dioxide and aminotrimethylene phosphonic acid in a mass ratio of 8:10.

[0050] Test case Flame retardancy: The oxygen index was tested according to GB / T 2406.2-2009 "Determination of flammability by oxygen index method for plastics - Part 2: Room temperature test". The sample shape was IV and the test method was Method A. The test results are shown in Table 1 below. Tensile strength: The tensile strength was tested according to GB / T 2951.11-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 11: General Test Methods - Thickness and Dimensional Measurements - Mechanical Properties Test". The test specimen was a dumbbell specimen with a thickness of 1.5 mm and a moving speed of 25 mm / min. The test results are shown in Table 2 below.

[0051] Table 1. Test results of insulation layer performance in Examples 1-5 and Comparative Example 1

[0052] The oxygen index of Examples 1-5 is higher than that of Comparative Example 1, indicating that the present invention improves the flame retardancy of the insulation layer by adding tetraethyl orthosilicate, Triton, and aminotrimethylenephosphonic acid as raw materials for flame retardants to obtain aminotrimethylenephosphonic acid composite silica.

[0053] Table 2. Test results of insulation layer performance in Examples 2 and 6-10

[0054] The tensile strength of Examples 6-8 is higher than that of Examples 2 and Examples 9-10, indicating that the present invention improves the tensile strength of the insulating layer by adding vermiculite, boehmite and zirconium phosphate as fillers.

[0055] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cross-linked polyethylene insulated overhead cable, characterized in that, From the inside out, it includes a conductor, a shielding layer, and an insulating layer; the conductor, from the inside out, includes a center conductor, an inner core layer, and an outer core layer; the inner core layer consists of 6 conductors; the outer core layer consists of 12 conductors. The raw materials of the insulation layer include the following components by weight: 60-80 parts of polyethylene resin, 10-20 parts of ethylene-1-octene copolymer, 0.8-1.5 parts of crosslinking agent, 10-20 parts of flame retardant, 1-3 parts of antioxidant, 1-2 parts of lubricant, 10-20 parts of filler, and 1-3 parts of compatibilizer; The flame retardant comprises the following raw materials: Tetramethyl silicate, Triton, and aminotrimethylenephosphonic acid.

2. The cross-linked polyethylene insulated overhead cable according to claim 1, characterized in that, The conductor is one of aluminum alloy conductor, pure aluminum conductor, or magnesium-aluminum alloy conductor.

3. The cross-linked polyethylene insulated overhead cable according to claim 1, characterized in that, The shielding layer is a metal shielding layer.

4. The cross-linked polyethylene insulated overhead cable according to claim 1, characterized in that, The method for preparing the flame retardant includes the following steps: A1. After adding tetraethyl orthosilicate to solvent I and mixing evenly, ammonia water is added to obtain premix solution I; A2. Add aminotrimethylenephosphonic acid to solvent II and mix thoroughly to obtain premixed solution II; A3. After mixing Triton into solvent III and mixing thoroughly, add premixed solution II and mix to obtain premixed solution III; A4. Add premixed liquid III to premixed liquid I and mix, then freeze-dry to obtain the flame retardant.

5. A cross-linked polyethylene insulated overhead cable according to claim 1, characterized in that, The crosslinking agent includes one or more of dicumyl peroxide, di-tert-butyldicumyl peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxide)hexane.

6. A cross-linked polyethylene insulated overhead cable according to claim 1, characterized in that, The antioxidant includes one or more of antioxidant 1010, antioxidant 168, and antioxidant 1076.

7. A cross-linked polyethylene insulated overhead cable according to claim 1, characterized in that, The lubricant includes one or more of zinc stearate, calcium stearate, and polyethylene wax.

8. A cross-linked polyethylene insulated overhead cable according to claim 1, characterized in that, The filler includes vermiculite, boehmite, and zirconium phosphate.

9. A cross-linked polyethylene insulated overhead cable according to claim 8, characterized in that, The mass ratio of vermiculite, boehmite, and zirconium phosphate is 5:3:1~3.

10. A method for preparing a cross-linked polyethylene insulated overhead cable, used to prepare the cross-linked polyethylene insulated overhead cable according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Twist 6 wires together outside the center wire to form the inner core layer; twist 12 wires together outside the inner core layer to form the conductor; S2. Wrap the shielding material around the outside of the conductor to form a shielding layer; S3. Extrude the insulation material onto the outside of the insulation layer and crosslink it to obtain the crosslinked polyethylene insulated overhead cable.

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