Outdoor overhead cable resistant to ultraviolet aging

Abstract

The application discloses an outdoor overhead cable with ultraviolet aging resistance, and belongs to the technical field of outdoor overhead cables. The cable comprises, from inside to outside, a stranded conductor, a conductor shielding layer, an insulation layer and an ultraviolet aging resistant outer sheath layer. The material of the ultraviolet aging resistant outer sheath layer comprises polymer resin, nano titanium dioxide, carbon black, an ultraviolet resistant agent, a composite antioxidant, an initiator and a processing aid. The ultraviolet resistant agent is obtained by reacting 2,5-dichlorothiophene with 3-buten-1-amine to obtain an intermediate, and then reacting the intermediate with 2,2',4,4';-tetrahydroxybenzophenone. The application forms a multiple protection mechanism by compounding nano titanium dioxide, carbon black and the self-prepared ultraviolet resistant agent in the sheath material. The ultraviolet resistant agent realizes wide spectrum chemical absorption through a large pi conjugated system and can be chemically grafted in a crosslinking process, effectively solving the problem that a traditional ultraviolet absorber is prone to migration, greatly improving the ultraviolet aging resistance of the cable and prolonging the service life.

Description

Technical Field

[0001] This invention belongs to the field of outdoor overhead cable technology, specifically, it relates to an outdoor overhead cable resistant to ultraviolet aging. Background Technology

[0002] With the accelerating pace of global informatization and the continuous growth in electricity demand, the coverage of power transmission networks is expanding daily. As a crucial component of power transmission, overhead cables face increasingly complex and demanding operating environments. Exposed to the outdoor environment for extended periods, overhead cables are inevitably subject to the combined effects of various natural factors, among which ultraviolet (UV) radiation is a major cause of aging in the cable's outer insulation and sheath materials. The high-energy photons of UV radiation can trigger a series of irreversible chemical reactions, including the breakage, cross-linking, and oxidative degradation of polymer chains. This leads to significant deterioration of the material's mechanical properties, electrical insulation performance, and surface characteristics, manifesting as surface cracking, pulverization, embrittlement, color fading, and a substantial decrease in mechanical strength. This performance degradation not only shortens the cable's service life but also significantly increases the risk of safety accidents such as insulation breakdown, short circuits, and even fires during operation, posing a serious threat to the safe and stable operation of the power system.

[0003] Currently, commonly used outdoor overhead cable sheathing materials mainly include polymers such as polyethylene, polyvinyl chloride, and cross-linked polyethylene. Although these materials possess certain mechanical strength and electrical insulation properties, their molecular structure lacks effective ultraviolet absorption or shielding units, leading to a significantly accelerated aging rate under prolonged direct sunlight, especially in environments with high ultraviolet intensity. Therefore, existing technologies typically employ modification methods such as adding light stabilizers, ultraviolet absorbers, or antioxidants to the matrix resin to delay photoaging. However, most light stabilizers, ultraviolet absorbers, or antioxidants have small molecular weights and are prone to migration, volatilization, or erosion by rainwater during long-term outdoor use, resulting in poor sustainability of the stabilizing effect. More critically, the design of existing UV-resistant cable materials often focuses on a single protective mechanism, lacking a multi-layered synergistic anti-aging system, making it difficult to simultaneously address multiple requirements such as resistance to ultraviolet radiation and thermo-oxidative aging. Therefore, it is urgent to solve these problems to meet the higher technical demands of the overhead cable technology field. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an outdoor overhead cable resistant to ultraviolet aging.

[0005] The objective of this invention can be achieved through the following technical solutions: An outdoor overhead cable resistant to ultraviolet aging comprises, from the inside out: a stranded conductor, a conductor shielding layer, an insulation layer, and an ultraviolet aging resistant outer sheath layer.

[0006] Preferably, the material of the UV-resistant outer sheath layer comprises the following raw materials in parts by weight: 80-90 parts polymer resin, 8-10 parts nano titanium dioxide, 4-6 parts carbon black, 2-4 parts UV resistant agent, 0.8-1.2 parts composite antioxidant, 0.2-0.3 parts initiator and 1-2 parts processing aid.

[0007] Preferably, the polymer resin is a blend of high-density polyethylene and low-density polyethylene in a mass ratio of 7:3.

[0008] Preferably, the composite antioxidant is obtained by compounding antioxidant 1010 and antioxidant DLTP in a mass ratio of 1:1.

[0009] Preferably, the processing aid is a mixture of stearate lubricant and polyethylene wax in a mass ratio of 1:1.

[0010] Preferably, the material of the UV-resistant outer sheath layer is prepared by the following steps: A1. Weigh the raw materials according to the mass fraction. First, premix the nano titanium dioxide, carbon black, UV resistant agent and composite antioxidant in a low-speed mixer for 5-10 minutes. Then add the polymer resin, initiator and processing aid, and continue mixing for 10-15 minutes to obtain a uniform premix. A2. Add the premixed material to a twin-screw extruder (temperature settings: feeding zone 140℃, conveying zone 165℃, melting zone 180℃, mixing zone 190℃, venting zone 185℃, homogenizing zone 180℃, die head 185℃, 280-320rpm) for melt blending. The melt is fully sheared and dispersed in the mixing zone, extruded through the die, cooled (water temperature 25℃), air-dried and pelletized to obtain the material for the UV-resistant outer sheath layer.

[0011] Preferably, the UV-resistant agent is prepared by the following steps: S1. Install a magnetic stirrer, reflux condenser, and constant pressure dropping funnel in a round-bottom flask. First, add 2,5-dichlorothiophene and anhydrous N,N-dimethylformamide to the flask, then add triethylamine. Subsequently, dissolve 3-buten-1-amine in anhydrous N,N-dimethylformamide and add it dropwise to the flask through the constant pressure dropping funnel. After the addition is complete, raise the temperature to 80-85℃ and stir the reaction for 10-12 hours. After the reaction is complete, cool to room temperature and follow the post-processing steps to obtain the intermediate of the UV resistant agent. S2. Install a magnetic stirrer and a reflux condenser in a round-bottom flask. Under nitrogen protection, add 2,2',4,4'-tetrahydroxybenzophenone, the intermediate of the UV resistant agent, and anhydrous N,N-dimethylformamide to the flask. Start stirring and add potassium carbonate, cuprous iodide (copper catalyst), and L-proline (ligand) in sequence. After the addition is complete, heat to 120-125℃ and stir the reaction for 12-16 hours. After the reaction is complete, cool to room temperature and follow the post-processing steps to obtain the UV resistant agent.

[0012] Preferably, the ratio of the amount of 2,5-dichlorothiophene to 3-buten-1-amine is 17.5-18.3g:7.1g.

[0013] Preferably, the ratio of the amount of 2,2',4,4'-tetrahydroxybenzophenone to the intermediate of the UV resistant agent is 26.6-29.5g:37.4g.

[0014] The reaction formula for the preparation process of UV resistant agents is as follows: This invention prepares a UV resistant agent through a two-step reaction. In the preparation process, the molar ratio of 2,5-dichlorothiophene to 3-buten-1-amine is first controlled to be close to 1:1, with 2,5-dichlorothiophene in excess, reserving one chlorine group for subsequent reactions. Then, by controlling the molar ratio of 2,2',4,4'-tetrahydroxybenzophenone to the UV resistant agent intermediate amine to be close to 1:2, with 2,2',4,4'-tetrahydroxybenzophenone in excess, side reactions in the reaction process are reduced.

[0015] The beneficial effects of this invention are: 1. This invention incorporates nano-titanium dioxide into the sheath material, utilizing its properties to efficiently absorb and scatter UVA band ultraviolet light, converting it into heat energy and reducing ultraviolet radiation penetration. 2. This invention incorporates carbon black into the sheath material, utilizing the highly conjugated structure of carbon black to achieve efficient physical shielding of ultraviolet light, thereby further improving UV resistance. 3. This invention adds a self-made UV absorber to the sheath material. The thiophene ring in the UV absorber molecule forms a large π conjugated system with the benzophenone structure. Through the intramolecular proton transfer mechanism in the excited state, it achieves broad-spectrum and efficient chemical absorption, capturing residual ultraviolet rays that penetrate the first two lines of defense. Chemical grafting is achieved in the cable sheath cross-linking process using terminal double bonds, which solves the industry pain point of easy migration of traditional small molecule UV absorbers. In summary, the sheath material of this invention is compounded with nano-titanium dioxide, carbon black and UV resistant agent, forming a multi-protection mechanism, which greatly improves the cable's resistance to UV aging and significantly extends the cable's service life under strong sunlight. It has important application value in the field of outdoor overhead cable technology. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1 Preparation of UV-resistant agents: S1. Install a magnetic stirrer, reflux condenser, and constant pressure dropping funnel in a round-bottom flask. First, add 52.5g of 2,5-dichlorothiophene and 100mL of anhydrous N,N-dimethylformamide to the flask, then add triethylamine. Subsequently, dissolve 21.3g of 3-buten-1-amine in 100mL of anhydrous N,N-dimethylformamide and add it dropwise to the flask through the constant pressure dropping funnel. After the addition is complete, raise the temperature to 80℃ and stir the reaction for 10h. After the reaction is complete, cool to room temperature, remove the solvent by rotary evaporation under reduced pressure, and purify by column chromatography (silica gel, petroleum ether / ethyl acetate gradient 20:1→10:1) to obtain the intermediate of the UV stabilizer. S2. Install a magnetic stirrer and reflux condenser in a round-bottom flask. Under nitrogen protection, add 26.6 g of 2,2',4,4'-tetrahydroxybenzophenone, 37.4 g of the intermediate of the UV resistant agent, and 150 mL of anhydrous N,N-dimethylformamide. Start stirring and add 28.5 g of potassium carbonate, 3.8 g of cuprous iodide (copper catalyst), and 4.6 g of L-proline (ligand) in sequence. After the addition is complete, heat to 120 °C and stir for 12 h. After the reaction is complete, cool to room temperature, filter, evaporate to dryness under reduced pressure, and purify by column chromatography (silica gel, dichloromethane / methanol gradient 40:1→20:1) to obtain the UV resistant agent. Materials for preparing UV-resistant outer sheath layers: A1. Weigh the raw materials according to the mass ratio. First, premix 8 parts of nano titanium dioxide, 4 parts of carbon black, 2 parts of UV resistant agent and 0.8 parts of composite antioxidant (antioxidant 1010 and antioxidant DLTP are compounded in a mass ratio of 1:1) in a low-speed mixer for 5 minutes. Then add 80 parts of polymer resin (high-density polyethylene and low-density polyethylene are compounded in a mass ratio of 7:3), 0.2 parts of di-tert-butyl peroxide and 1 part of processing aid (stearate lubricant and polyethylene wax are compounded in a mass ratio of 1:1). Continue mixing for 10 minutes to obtain a uniform premix. A2. Add the premixed material to a twin-screw extruder (temperature settings: feeding zone 140℃, conveying zone 165℃, melting zone 180℃, mixing zone 190℃, venting zone 185℃, homogenizing zone 180℃, die head 185℃, 280rpm) for melt blending. The melt is fully sheared and dispersed in the mixing zone, extruded through the die, cooled (water temperature 25℃), air-dried and pelletized to obtain the material for the UV-resistant outer sheath layer.

[0018] An outdoor overhead cable resistant to ultraviolet aging is prepared by the following steps: Soft copper monofilaments are stranded into stranded conductors using a stranding machine according to a standard stranding method. Using a three-layer co-extrusion machine, the conductor shielding material (by weight: 85 parts low-density polyethylene, 12 parts conductive carbon black, 1.5 parts crosslinking agent DCP, 0.5 parts antioxidant), the insulation material (by weight: 92 parts high-density polyethylene, 2 parts crosslinking agent DCP, 1.5 parts primary antioxidant 1010, 1.5 parts secondary antioxidant DLTP), and the UV-resistant outer sheath material are melted in an extruder and then coated onto the conductor in one go through the three-layer co-extrusion die head. After extrusion, it is immediately passed through a nitrogen-filled dry crosslinking tube (tube temperature 280℃, nitrogen pressure 0.8MPa) for crosslinking. After water cooling and curing, a UV-resistant outdoor overhead cable is obtained.

[0019] Example 2 Preparation of UV-resistant agents: S1. Install a magnetic stirrer, reflux condenser, and constant pressure dropping funnel in a round-bottom flask. First, add 54.9 g of 2,5-dichlorothiophene and 100 mL of anhydrous N,N-dimethylformamide to the flask, then add triethylamine. Subsequently, dissolve 21.3 g of 3-buten-1-amine in 100 mL of anhydrous N,N-dimethylformamide and add it dropwise to the flask through the constant pressure dropping funnel. After the addition is complete, raise the temperature to 85 °C and stir the reaction for 12 h. After the reaction is complete, cool to room temperature, remove the solvent by rotary evaporation under reduced pressure, and purify by column chromatography (silica gel, petroleum ether / ethyl acetate gradient 20:1→10:1) to obtain the intermediate of the UV stabilizer. S2. Install a magnetic stirrer and reflux condenser in a round-bottom flask. Under nitrogen protection, add 26.6-29.5 g of 2,2',4,4'-tetrahydroxybenzophenone, 37.4 g of the intermediate of the UV resistant agent, and 150 mL of anhydrous N,N-dimethylformamide. Start stirring and add 28.5 g of potassium carbonate, 3.8 g of cuprous iodide (copper catalyst), and 4.6 g of L-proline (ligand) in sequence. After the addition is complete, heat to 125 °C and stir for 16 h. After the reaction is complete, cool to room temperature, filter, evaporate to dryness under reduced pressure, and purify by column chromatography (silica gel, dichloromethane / methanol gradient 40:1→20:1) to obtain the UV resistant agent. Materials for preparing UV-resistant outer sheath layers: A1. Weigh the raw materials according to the mass ratio. First, premix 9 parts of nano titanium dioxide, 5 parts of carbon black, 3 parts of UV resistant agent and 1.0 part of composite antioxidant (antioxidant 1010 and antioxidant DLTP are compounded in a mass ratio of 1:1) in a low-speed mixer for 10 minutes. Then add 85 parts of polymer resin (high-density polyethylene and low-density polyethylene are compounded in a mass ratio of 7:3), 0.25 parts of di-tert-butyl peroxide and 1.5 parts of processing aid (stearate lubricant and polyethylene wax are compounded in a mass ratio of 1:1). Continue mixing for 15 minutes to obtain a uniform premix. A2. Add the premixed material to a twin-screw extruder (temperature settings: feeding zone 140℃, conveying zone 165℃, melting zone 180℃, mixing zone 190℃, venting zone 185℃, homogenizing zone 180℃, die head 185℃, 320rpm) for melt blending. The melt is fully sheared and dispersed in the mixing zone, extruded through the die, cooled (water temperature 25℃), air-dried and pelletized to obtain the material for the UV-resistant outer sheath layer.

[0020] An outdoor overhead cable resistant to ultraviolet aging is prepared by the following steps: Soft copper monofilaments are stranded into stranded conductors using a stranding machine according to a standard stranding method. Using a three-layer co-extrusion machine, the conductor shielding material (by weight: 85 parts low-density polyethylene, 12 parts conductive carbon black, 1.5 parts crosslinking agent DCP, 0.5 parts antioxidant), the insulation material (by weight: 92 parts high-density polyethylene, 2 parts crosslinking agent DCP, 1.5 parts primary antioxidant 1010, 1.5 parts secondary antioxidant DLTP), and the UV-resistant outer sheath material are melted in an extruder and then coated onto the conductor in one go through the three-layer co-extrusion die head. After extrusion, it is immediately passed through a nitrogen-filled dry crosslinking tube (tube temperature 280℃, nitrogen pressure 0.8MPa) for crosslinking. After water cooling and curing, a UV-resistant outdoor overhead cable is obtained.

[0021] Example 3 The only difference between this embodiment and Embodiment 2 is that, in this embodiment, the material of the UV-resistant outer sheath layer is prepared through the following steps: A1. Weigh the raw materials according to the mass ratio. First, premix 10 parts of nano titanium dioxide, 6 parts of carbon black, 4 parts of UV resistant agent and 1.2 parts of composite antioxidant (antioxidant 1010 and antioxidant DLTP are compounded in a mass ratio of 1:1) in a low-speed mixer for 10 minutes. Then add 90 parts of polymer resin (high-density polyethylene and low-density polyethylene are compounded in a mass ratio of 7:3), 0.3 parts of di-tert-butyl peroxide and 2 parts of processing aid (stearate lubricant and polyethylene wax are compounded in a mass ratio of 1:1). Continue mixing for 15 minutes to obtain a uniform premix. A2. Add the premixed material to a twin-screw extruder (temperature settings: feeding zone 140℃, conveying zone 165℃, melting zone 180℃, mixing zone 190℃, venting zone 185℃, homogenizing zone 180℃, die head 185℃, 320rpm) for melt blending. The melt is fully sheared and dispersed in the mixing zone, extruded through the die, cooled (water temperature 25℃), air-dried and pelletized to obtain the material for the UV-resistant outer sheath layer.

[0022] An outdoor overhead cable resistant to ultraviolet aging is prepared by the following steps: Soft copper monofilaments are stranded into stranded conductors using a stranding machine according to a standard stranding method. Using a three-layer co-extrusion machine, the conductor shielding material (by weight: 85 parts low-density polyethylene, 12 parts conductive carbon black, 1.5 parts crosslinking agent DCP, 0.5 parts antioxidant), the insulation material (by weight: 92 parts high-density polyethylene, 2 parts crosslinking agent DCP, 1.5 parts primary antioxidant 1010, 1.5 parts secondary antioxidant DLTP), and the UV-resistant outer sheath material are melted in an extruder and then coated onto the conductor in one go through the three-layer co-extrusion die head. After extrusion, it is immediately passed through a nitrogen-filled dry crosslinking tube (tube temperature 280℃, nitrogen pressure 0.8MPa) for crosslinking. After water cooling and curing, a UV-resistant outdoor overhead cable is obtained.

[0023] Comparative Example 1 The only difference between this comparative example and Example 3 is that in this comparative example, an equal amount of UV absorber UV-9 was used to replace the UV resistant agent to obtain the cable.

[0024] Comparative Example 2 The only difference between this comparative example and Example 3 is that no UV resistant agent was added in this comparative example to obtain the cable.

[0025] Comparative Example 3 The only difference between this comparative example and Example 3 is that in this comparative example, nano-titanium dioxide and carbon black are not added to obtain the cable.

[0026] The cables prepared in Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 were exposed to natural outdoor light for 2000 hours, and the surface condition of the cables was observed.

[0027] The outer sheath materials of Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 were extruded separately and aged for 1000 hours according to GB / T16422.3-2022 standard. The tensile strength before and after aging was measured (GB / T 1040.1-2025), and the tensile strength retention rate was calculated (tensile strength after aging / initial tensile strength × 100%). The measurement results are shown in Table 1: Table 1 As can be seen from the measurement results in Table 1, the cable prepared by the embodiment of the present invention has a higher UV aging resistance than the comparative example due to the combination of nano titanium dioxide, carbon black and UV resistant agent in the sheath material, forming a multi-protection mechanism. It also has a longer service life. Therefore, the present invention has important application value in the field of outdoor overhead cable technology.

[0028] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. An outdoor overhead cable resistant to ultraviolet aging, comprising, from the inside out: The stranded conductor, conductor shielding layer, insulation layer, and UV-resistant outer sheath layer are characterized in that the material of the UV-resistant outer sheath layer comprises the following raw materials in parts by weight: 80-90 parts polymer resin, 8-10 parts nano titanium dioxide, 4-6 parts carbon black, 2-4 parts UV resistant agent, 0.8-1.2 parts composite antioxidant, 0.2-0.3 parts initiator, and 1-2 parts processing aid.

2. The outdoor overhead cable resistant to ultraviolet aging according to claim 1, characterized in that, The polymer resin is obtained by blending high-density polyethylene and low-density polyethylene in a mass ratio of 7:

3.

3. The outdoor overhead cable resistant to ultraviolet aging according to claim 1, characterized in that, The composite antioxidant is obtained by compounding antioxidant 1010 and antioxidant DLTP in a mass ratio of 1:

1.

4. The outdoor overhead cable resistant to ultraviolet aging according to claim 1, characterized in that, The processing aid is a mixture of stearate lubricant and polyethylene wax in a mass ratio of 1:

1.

5. The outdoor overhead cable resistant to ultraviolet aging according to claim 1, characterized in that, The material of the UV-resistant outer sheath layer is prepared through the following steps: A1. Premix nano-titanium dioxide, carbon black, UV resistant agent and composite antioxidant in a mixer, then add polymer resin, initiator and processing aid, and continue mixing to obtain a uniform premix. A2. Add the premixed material to a twin-screw extruder for melt blending. The melt is fully sheared and dispersed, extruded through a die, cooled, air-dried, and pelletized to obtain the material for the UV-resistant outer sheath layer.

6. The outdoor overhead cable resistant to ultraviolet aging according to claim 1, characterized in that, The UV-resistant agent is prepared by the following steps: S1. Add 2,5-dichlorothiophene and anhydrous N,N-dimethylformamide to a flask, then add triethylamine. Subsequently, dissolve 3-buten-1-amine in anhydrous N,N-dimethylformamide and add it dropwise to the flask. After the dropwise addition is complete, raise the temperature to 80-85℃ and stir the reaction for 10-12 hours. Once the reaction is complete, the intermediate of the UV resistant agent is obtained. S2. Add 2,2',4,4'-tetrahydroxybenzophenone, the intermediate of the UV resistant agent, and anhydrous N,N-dimethylformamide to the flask, start stirring, and add potassium carbonate, cuprous iodide, and L-proline. After the addition is complete, stir and react at 120-125℃ for 12-16 hours. The reaction is complete, and the UV resistant agent is obtained.

7. The outdoor overhead cable resistant to ultraviolet aging according to claim 6, characterized in that, The ratio of 2,5-dichlorothiophene to 3-buten-1-amine is 17.5-18.3 g: 7.1 g.

8. The outdoor overhead cable resistant to ultraviolet aging according to claim 6, characterized in that, The ratio of the amount of the intermediate of 2,2',4,4'-tetrahydroxybenzophenone and the UV resistant agent is 26.6-29.5g:37.4g.

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