Weather-resistant low-voltage cable and method for manufacturing the same

Abstract

The application relates to the field of cables, in particular to a weather-resistant low-voltage cable and a preparation method thereof. The weather-resistant low-voltage cable and the preparation method thereof comprise a conductor, an insulation layer, a shielding layer and a protective layer, the insulation layer comprises the following raw materials in parts by weight: 100-150 parts of thermoplastic polyurethane, 1-2 parts of a light stabilizing system, 2-4 parts of environment-responsive microcapsules, 1.5-2.5 parts of fumed silica, 11-16 parts of a flame retardant and 0.5-0.7 parts of a processing aid; the environment-responsive microcapsules take polyurethane as a wall material and take bromocresol purple and a siloxane self-repairing agent as core materials. The cable of the application captures free radicals caused by ultraviolet rays through the light stabilizing system, inhibits the oxidative degradation of the matrix resin, prolongs the service life of the cable in an outdoor ultraviolet light and high-low temperature alternating environment. Meanwhile, the environment-responsive microcapsules are added to continue timely repair of the aging and cracked insulation layer, greatly improving the anti-aging effect of the cable.

Description

Technical Field

[0001] This application relates to the field of cables, and in particular to a weather-resistant low-voltage cable and its manufacturing method. Background Technology

[0002] Cables are conductors covered with insulation, protective layers, and shielding layers used to transmit electrical or signal current and voltage. They can be classified into high-voltage cables and low-voltage cables according to voltage. Although low-voltage cable lines are more expensive and more difficult to lay and maintain compared to low-voltage overhead lines and low-voltage insulated overhead lines, they are widely used in low-voltage power distribution systems due to their reliable operation, lack of poles, lack of ground occupation, unobstructed appearance, and less susceptibility to external influences.

[0003] The insulation layer of low-voltage cables is generally made of cross-linked polyethylene (XLPE). Although XLPE has many unique advantages, it also faces the problem of aging under the corrosive effects of physical and chemical factors. During the operation of a cable under current load, a large amount of heat accumulates, accelerating the movement of molecules in the insulation material and producing complex physical and chemical reactions. This leads to a continuous weakening of the cross-linking degree and insulation performance of the insulation material.

[0004] To improve the aging resistance of XLPE materials, aging-resistant additives such as antioxidants, ultraviolet absorbers, and light stabilizers are generally added during the preparation of XLPE materials. Antioxidants can effectively slow down the aging rate of polyethylene, allowing it to be used for a long time at room temperature; ultraviolet absorbers and light stabilizers can absorb or reflect and scatter ultraviolet rays, reducing the damage of ultraviolet rays to the insulating materials.

[0005] Regarding the aforementioned technologies, the applicant believes that commonly used anti-aging additives are generally organic additives. During high-voltage current load operation, under the combined action of high temperature and current, they are prone to migration and precipitation within the insulating material, resulting in their inability to maintain their effectiveness for a long time. Summary of the Invention

[0006] To improve the weather resistance of low-voltage cables, this application provides a weather-resistant low-voltage cable and its manufacturing method.

[0007] In the first aspect, this application provides a weather-resistant low-voltage cable, which adopts the following technical solution.

[0008] A weather-resistant low-voltage cable and its preparation method are disclosed, comprising a conductor, an insulation layer, a shielding layer, and a protective layer. The insulation layer comprises the following raw materials in parts by weight: 100-150 parts thermoplastic polyurethane, 1-2 parts light-stabilized system, 2-4 parts environmentally responsive microcapsules, 1.5-2.5 parts fumed silica, 11-16 parts flame retardant, and 0.5-0.7 parts processing aid.

[0009] The environmentally responsive microcapsules use polyurethane as the wall material and bromocresol purple and siloxane self-healing agent as the core material.

[0010] By adopting the above technical solution, the light-stabilized system can effectively capture free radicals induced by ultraviolet rays, inhibit the oxidative degradation of the matrix resin, and extend the service life of the cable in outdoor ultraviolet and high and low temperature alternating environments.

[0011] The polyurethane wall material is encapsulated with bromocresol purple and siloxane self-healing agent in microcapsules. When the insulation layer produces acidic peroxides due to aging, the bromocresol purple color change triggers the microcapsule rupture. The released siloxane self-healing agent can cross-link into a film at the micro-cracks, actively repairing the damage and preventing further aging.

[0012] Siloxane self-healing agents have low surface energy and fluidity. When the insulation layer cracks due to aging, the repair agent can quickly migrate to the damaged area and form an elastic network through hydroxyl condensation reaction. After repair, the breakdown strength recovery rate of the insulation layer is high.

[0013] Bromocresol purple, as a pH indicator, changes from purple to yellow in an acidic environment during the early stages of insulation aging. This color change allows for a direct assessment of the cable's aging level, facilitating early maintenance and replacement and reducing the risk of sudden failures.

[0014] Nanoscale fumed silica is uniformly dispersed in the matrix resin, forming "physical cross-linking points," which improves the tensile strength and elongation at break of the insulation layer, while reducing the risk of cracking caused by thermal expansion and contraction.

[0015] Furthermore, the method for preparing the environmentally responsive microcapsules is as follows:

[0016] 1) Weather-resistant low-voltage cables

[0017] The solution used bromocresol purple and polyvinyl alcohol as the inner aqueous phase, hydroxyl-terminated polydimethylsiloxane and dibutyltin dilaurate as the oil phase, and polyvinyl alcohol solution as the outer aqueous phase.

[0018] The internal aqueous phase is dispersed in the oil phase to form a W / O primary emulsion. The primary emulsion is then injected into the external aqueous phase and sheared to form a W / O / W emulsion.

[0019] 2) Interfacial polymerization forms wall material

[0020] Hydroxyl-terminated polybutadiene was mixed with a chain extender and pre-dispersed in a W / O / W emulsion. Then, a toluene diisocyanate solution was injected, and the mixture was reacted at 54-56℃ for 175-185 min to obtain microcapsules.

[0021] By adopting the above technical solution, the inner aqueous phase is encapsulated by the oil phase and then covered by polyurethane wall material, forming a "water-oil-water" three-layer structure. This design isolates bromocresol purple and siloxane self-healing agent for storage, avoiding premature reaction between the two and extending the service life of the microcapsules.

[0022] The reaction with toluene diisocyanate forms a flexible polyurethane elastomer wall material. Compared to pure polyurethane wall material, it exhibits increased elongation at break, enhanced impact resistance, and better resistance to mechanical stress during cable processing. Reaction conditions of 54-56℃ and 175-185 minutes ensure the degree of polyurethane crosslinking, resulting in a dense and uniform wall material that combines strength and permeability.

[0023] The obtained microcapsules contain dibutyltin dilaurate as a siloxane crosslinking catalyst, which is encapsulated in the oil phase and directly contacts the siloxane, thus improving catalytic efficiency and repair speed. The low surface energy of hydroxyl-terminated polydimethylsiloxane enables it to spread rapidly at microcracks, thereby improving the volume resistivity recovery rate of the repaired insulation layer.

[0024] When the external environment changes, such as the penetration of acidic substances, the PVA film dissolves under acidic conditions, triggering the bromocresol purple color change and releasing siloxanes, achieving a precise response. The introduction of conjugated double bonds of hydroxyl-terminated polybutadiene into the polyurethane wall material can absorb some ultraviolet light (290-400nm), reducing the photodegradation of bromocresol purple and extending the effective duration of the warning function in outdoor environments.

[0025] Furthermore, the weight ratio of bromocresol purple to hydroxyl-terminated polydimethylsiloxane is 1:(80-90).

[0026] By adopting the above technical solution, a weight ratio of 1:(80-90) is determined to ensure that bromocresol purple is kept at an appropriate concentration in the microcapsules. This ensures that the acidic environment caused by the aging of the insulation layer can be sensitively detected and timely color change warning can be given, while the stability of the microcapsules will not be affected by excessive concentration. At the same time, a sufficient amount of hydroxyl-terminated polydimethylsiloxane acts as a self-healing agent. After the microcapsules rupture, it can fully cover and repair the micro-cracks in the insulation layer, thereby improving the self-healing efficiency and significantly improving the insulation performance recovery rate.

[0027] At this ratio, the chemical interference between bromocresol purple and hydroxyl-terminated polydimethylsiloxane is reduced, effectively suppressing the risk of premature reaction or deterioration of the core material. This allows the microcapsules to maintain structural and performance stability during cable processing and long-term use, extending their service life and ensuring long-term stable operation of the cable.

[0028] Furthermore, the weight ratio of toluene diisocyanate to hydroxyl-terminated polybutadiene is (1.4-1.5):1.

[0029] By adopting the above technical solution, a mixing ratio of 1.4-1.5:1 ensures full cross-linking of polyurethane segments, forming a three-dimensional network structure, with a higher cross-linking density than traditional ratios. An appropriate excess of TDI promotes the formation of urethane bonds (-NHCOO-) and urea bonds (-NHCONH-), reducing microporous defects in the wall material, decreasing oxygen and water vapor permeability, and delaying core material aging.

[0030] The dense wall material structure effectively blocks external environmental factors such as ultraviolet rays, oxygen, and moisture from eroding the core material, reduces the photodegradation rate of bromocresol purple, and slows down the oxidation and deterioration rate of the siloxane self-healing agent.

[0031] By adjusting the crosslinking density, the wall material begins to degrade slowly at pH < 6.0 or temperature > 70℃, which is highly matched with the color change threshold (pH 5.5-6.5) of bromocresol purple, thus achieving integrated "sensing-response".

[0032] Furthermore, the droplet size of the W / O / W emulsion is 8-12 μm.

[0033] Furthermore, the injection rate of the toluene diisocyanate solution is 1 mL / min·L.

[0034] By employing the above technical solution, an injection rate of 1 mL / min·L allows TDI and hydroxyl-terminated polybutadiene to diffuse slowly at the W / O / W emulsion interface, avoiding the explosive polymerization caused by excessively high local isocyanate concentrations. The crosslinking reaction rate is controlled at 0.2-0.3 mol / (L·h), forming a uniform polyurethane elastomer network. Uniform injection of the TDI solution results in a uniform shear field, reduced average microcapsule size, decreased monodispersity coefficient, and improved sphericity, which is more conducive to uniform dispersion in the insulating layer.

[0035] Slow injection promotes the formation of flexible segments with high NHCOO content on the inner side of the wall material (near the core material) and rigid segments with high urea bond content on the outer side, thereby improving the interfacial bonding strength and reducing the risk of core material leakage.

[0036] Furthermore, the method for preparing the environmentally responsive microcapsules also includes:

[0037] 3) Surface functionalization treatment

[0038] The microcapsules were immersed in titanium dioxide sol and dried at 60°C to form a 0.2 μm thick protective layer; then the surface was treated with a silane coupling agent.

[0039] By employing the above technical solution, the protective layer formed by titanium dioxide sol can effectively shield 290-400nm ultraviolet rays, with an ultraviolet blocking rate of over 95%, significantly delaying the photodegradation of bromocresol violet and siloxane self-healing agents, thus extending the effective lifespan of microcapsules in outdoor environments. Simultaneously, the photocatalytic activity of titanium dioxide can decompose trace amounts of oxygen and free radicals upon contact, reducing the risk of core material oxidation. The titanium dioxide coating possesses good chemical inertness; in acidic or alkaline environments (pH 3-11), the swelling rate of the microcapsule wall material decreases, preventing the penetration of external corrosive media and ensuring the stability of the core material.

[0040] The silane coupling agent forms an organic-inorganic transition layer on the surface of the microcapsule. One end undergoes a condensation reaction with the hydroxyl groups of the titanium dioxide coating, while the organic groups at the other end entangle and physically adsorb with the matrix resin. This enhances the interfacial adhesion strength between the microcapsule and the matrix, effectively preventing microcapsule detachment or aggregation during processing and use. After surface treatment, the surface energy of the microcapsule is reduced, resulting in a better match with the matrix surface energy. This improves the uniformity of dispersion within the insulating layer, avoiding performance inconsistencies caused by excessively high local concentrations.

[0041] Furthermore, the light stabilizer system is a benzotriazole and tetramethylpiperidine derivative coated with a nano-SiO2 carrier.

[0042] By employing the above technical solutions, benzotriazole can effectively absorb ultraviolet light in the 290-400nm range, while tetramethylpiperidine derivatives can capture free radicals generated by ultraviolet radiation. The combination of these two forms a dual "absorption-scavenging" protection mechanism, improving both ultraviolet blocking efficiency and free radical scavenging efficiency. The high specific surface area and nanoscale size (10-50nm) of the nano-SiO2 carrier ensures uniform dispersion of the light stabilizer in the matrix resin, preventing agglomeration. Simultaneously, the inorganic network structure of SiO2 prevents the migration or precipitation of the light stabilizer under high temperature and high humidity conditions, increasing its effective retention rate in the insulating layer and extending the photostable action time.

[0043] Nano-SiO2 carriers can act as physical reinforcing fillers, working synergistically with fumed silica to improve the tensile strength of the insulation layer.

[0044] Furthermore, the matrix resin is thermoplastic polyurethane.

[0045] Secondly, this application provides a method for preparing a weather-resistant low-voltage cable, which adopts the following technical solution.

[0046] A method for manufacturing a weather-resistant low-voltage cable includes the following steps:

[0047] By sequentially wrapping the conductor with an insulation layer, a shielding layer, and a protective layer, a weather-resistant low-voltage cable is obtained.

[0048] In summary, this application has the following beneficial effects:

[0049] This application utilizes a light-stabilizing system to capture free radicals induced by ultraviolet radiation, inhibiting the oxidative degradation of the matrix resin and extending the cable's service life under outdoor ultraviolet radiation and alternating high and low temperature environments. Simultaneously, environmentally responsive microcapsules are added. These microcapsules encapsulate bromocresol purple and a siloxane self-healing agent within the polyurethane wall material. When the insulation layer produces acidic peroxides due to aging, the bromocresol purple color change triggers the microcapsule rupture, releasing the siloxane self-healing agent which cross-links to form a film at the micro-cracks, actively repairing damage and preventing further aging. When cracks appear in the insulation layer due to aging, the repair agent rapidly migrates to the damaged area, forming an elastic network through hydroxyl condensation reactions, resulting in a high breakdown strength recovery rate for the repaired insulation layer. Detailed Implementation

[0050] The present application will be further described in detail below with reference to the embodiments.

[0051] Example of raw material and intermediate preparation

[0052] raw material

[0053] All raw materials used in the embodiments of this application are commercially available.

[0054] Thermoplastic polyurethane, cold resistance -60℃, tear resistance >50kN / m;

[0055] Benztriazole coated with nano-SiO2 support, with a particle size of 80 nm;

[0056] Tetramethylpiperidine derivatives with a molecular weight >2000;

[0057] Fumed silica, hydrophobic;

[0058] Flame retardant, aluminum hypophosphite and zinc borate in a weight ratio of 8:3;

[0059] Processing aids, consisting of oxidized polyethylene wax and antioxidant 1010 in a weight ratio of 3:2;

[0060] Bromocresol purple, purity >99%, pH 5.2-6.8;

[0061] Polyvinyl alcohol (PVA-1788, degree of alcoholysis 88%)

[0062] Hydroxyl-terminated polydimethylsiloxane, viscosity 5000 cP, hydroxyl value 0.8 mmol / g;

[0063] Dibutyltin dilaurate, diluted to 10% before use;

[0064] Nanomolecular sieve (3Å), pre-activated at 200℃ for 2h;

[0065] Cyclohexane, industrial grade, moisture <100ppm;

[0066] Hydroxyl-terminated polybutadiene, hydroxyl value 0.7 mmol / g, Mn=3000;

[0067] The chain extender, ethylenediamine, should be prepared as a 10% aqueous solution for use.

[0068] Toluene diisocyanate, 2,4-isomer content ≥80%;

[0069] Xylene, dehydrated, moisture content <50ppm;

[0070] Titanium dioxide sol, solid content 10%, particle size 50nm;

[0071] The silane coupling agent, KH550, should be prepared as a 1% alcohol solution for use.

[0072] Preparation Example

[0073] Preparation Examples 1-7

[0074] A method for preparing environmentally responsive microcapsules is as follows:

[0075] 1) Weather-resistant low-voltage cables

[0076] According to the raw material ratio in Table 1, deionized water, bromocresol purple, and polyvinyl alcohol are mixed as the inner aqueous phase, hydroxyl-terminated polydimethylsiloxane, dibutyltin dilaurate, nano molecular sieve, and cyclohexane are mixed as the oil phase, and deionized water, polyvinyl alcohol, and sodium dodecyl sulfate are mixed as the outer aqueous phase.

[0077] The internal aqueous phase was dispersed in the oil phase at a rotation speed of 10,000 rpm to form a W / O primary emulsion. The primary emulsion was then injected into the external aqueous phase and sheared at 5,000 rpm to form a W / O / W emulsion. The droplet size was controlled to be 10 μm.

[0078] 2) Interfacial polymerization forms wall material

[0079] Toluene diisocyanate was dissolved in xylene to obtain a toluene diisocyanate solution. Hydroxyl-terminated polybutadiene, chain extender and triethylamine were mixed and pre-dispersed in a W / O / W emulsion. Then, the mixture was injected into the toluene diisocyanate solution at a rate of 1 mL / min·L and reacted at 55 °C for 180 min. The mixture was washed three times by alternating centrifugation with ethanol / water, then freeze-dried at -40 °C for 24 h, and then vacuum-dried at 25 °C to obtain microcapsules.

[0080] Table 1. Raw material ratio table for preparation examples 1-7 (kg)

[0081]

[0082] Preparation Example 8

[0083] Unlike Preparation Example 1, the injection rate of the toluene diisocyanate solution in Preparation Example 8 was 2 mL / min·L.

[0084] Preparation Example 9

[0085] A method for preparing environmentally responsive microcapsules is as follows:

[0086] 1) Weather-resistant low-voltage cables

[0087] According to the raw material ratio of Preparation Example 1 in Table 1, deionized water, bromocresol purple and polyvinyl alcohol were mixed as the inner aqueous phase, hydroxyl-terminated polydimethylsiloxane, dibutyltin dilaurate, nano molecular sieve and cyclohexane were mixed as the oil phase, and deionized water, polyvinyl alcohol and sodium dodecyl sulfate were mixed as the outer aqueous phase.

[0088] The internal aqueous phase was dispersed in the oil phase at a rotation speed of 10,000 rpm to form a W / O primary emulsion. The primary emulsion was then injected into the external aqueous phase and sheared at 5,000 rpm to form a W / O / W emulsion. The droplet size was controlled to be 10 μm.

[0089] 2) Interfacial polymerization forms wall material

[0090] Toluene diisocyanate was dissolved in xylene to obtain a toluene diisocyanate solution; hydroxyl-terminated polybutadiene, chain extender and triethylamine were mixed and pre-dispersed in a W / O / W emulsion, and then injected into the toluene diisocyanate solution at a rate of 1 mL / min·L, and reacted at 55 °C for 180 min to obtain microcapsules;

[0091] 3) Surface functionalization treatment

[0092] Microcapsules were immersed in titanium dioxide sol and dried at 60°C to form a 0.2 μm thick protective layer.

[0093] The surface is then treated with a silane coupling agent.

[0094] Wash three times by alternating centrifugation with ethanol and water, then freeze-dry at -40°C for 24 hours, and then vacuum-dry at 25°C.

[0095] Preparation Example 10

[0096] Unlike Preparation Example 9, Preparation Example 10 involves surface functionalization treatment (3).

[0097] The surface of the microcapsules was treated with a silane coupling agent;

[0098] Wash three times by alternating centrifugation with ethanol and water, then freeze-dry at -40°C for 24 hours, and then vacuum-dry at 25°C.

[0099] Example

[0100] Examples 1-3

[0101] A weather-resistant low-voltage cable, the method for its preparation is as follows:

[0102] S1. Insulation layer wrapping

[0103] 1. According to the raw material ratio in Table 2, heat the matrix resin to 200°C, add the light stabilizer system, fumed silica and flame retardant, and mix at 400 rpm for 15 minutes.

[0104] 2. Cool to 110℃, add environmentally responsive microcapsules, and stir at 150 rpm for 10 minutes to break them;

[0105] 3. Finally, add the processing aids and continue mixing for 5 minutes to ensure the materials are evenly dispersed, thus obtaining the insulation layer mixture;

[0106] 4. The mixture is added to the screw extruder and extruded through the die to coat the conductor surface, forming an insulating layer. The extrusion process parameters are as follows: extruder temperature: feeding section 90-100℃, compression section 110-120℃, homogenization section 120-130℃, die head 125-135℃, screw speed 40-60 rpm, cooling method: water cooling, water temperature 20-30℃.

[0107] S2. Wrapping shielding layer

[0108] The aluminum foil shielding layer is wrapped around the insulating layer;

[0109] S3. Protective Wrap

[0110] A polyethylene protective layer is wrapped around the shielding layer.

[0111] Table 2 Raw material ratio table for Examples 1-3 (kg)

[0112]

[0113] The matrix resin is thermoplastic polyurethane; the light stabilizer system is a nano-SiO2 carrier-coated benzotriazole and tetramethylpiperidine derivative in a weight ratio of 3:2; and the environmentally appropriate microcapsules are derived from Preparation Example 1.

[0114] Example 4-12

[0115] Unlike Example 1, the environmentally responsive microcapsules in Examples 4-12 were derived from Preparation Examples 2-10, respectively.

[0116] Comparative Example

[0117] Comparative Example 1

[0118] Unlike Example 1, in Comparative Example 1, the corresponding microcapsules in the environment were replaced with an equal amount of matrix resin.

[0119] Performance testing

[0120] Following the method in S1 of the examples and comparative examples, insulating materials were prepared without wrapping during extrusion, and the following performance tests were conducted. The test results are shown in Table 3.

[0121] Mechanical properties: The tensile strength and elongation at break of the protective sheaths obtained in the examples and comparative examples were tested in accordance with GB / T2951.11-2008, "General test methods for insulation and sheathing materials of cables and optical fibers - Part 11: General test methods for thickness and dimensional measurement and mechanical properties test".

[0122] Aging test: The cable obtained in Example S1 and Comparative Example S1 had a cross-section of 1000 mm². 2 Connect the cable to a 1kV circuit, and then, referring to GB-T16422.3-2022 "Laboratory Light Source Exposure Test Methods for Plastics - Part 3: Fluorescent Ultraviolet Lamps", use a combination of four types of ultraviolet lamps for ultraviolet aging, supplemented by high-temperature aging at 60℃. After aging for 25 days, peel off the protective sleeve and test the tensile strength and elongation at break again.

[0123] Calculate the aging retention rate:

[0124] Tensile strength retention rate after aging = tensile strength after aging / tensile strength before aging × 100%;

[0125] Fracture strength retention rate after aging = fracture strength after aging / fracture strength before aging × 100%.

[0126] Table 3 Performance Test Results

[0127]

[0128] Combining Examples 1-12 with Comparative Example 1, and referring to Table 3, it can be seen that after the cables made of the insulating materials in Examples 1-12 are connected to a 1kV circuit and subjected to aging tests under ultraviolet irradiation, their tensile strength aging retention rate and tensile breaking strength retention rate are both greater than those in Comparative Example 1. This indicates that the insulating material prepared in this application has better aging resistance.

[0129] Combining Example 1 and Comparative Example 1, and referring to Table 3, it can be seen that the cable made of the insulating material in Example 1, after being connected to a 1kV circuit and subjected to aging tests under ultraviolet irradiation, exhibited greater aging retention rate of tensile strength and tensile retention rate of breaking strength than that in Comparative Example 1. This indicates that the insulating material prepared in Example 1 has superior aging resistance. This may be because...

[0130] Combining Examples 2 and 4, and referring to Table 2, it can be seen that the cable made of the insulating material in Example 4, after being connected to a 1kV circuit and subjected to aging tests under ultraviolet irradiation, exhibited greater aging retention rate of tensile strength and tensile retention rate of breaking strength than that in Example 2. This indicates that the addition of thermally conductive filler can further improve the anti-aging performance of the insulating material. This may be because the microcapsules of the polyurethane wall material encapsulate bromocresol purple and siloxane self-healing agents. When the insulation layer produces acidic substances due to aging, the bromocresol purple color change triggers the microcapsule rupture, releasing the siloxane self-healing agent which can cross-link into a film at the micro-cracks, actively repairing the damage and preventing further aging. When cracks appear in the insulation layer, the repair agent can quickly migrate to the damaged area, forming an elastic network through hydroxyl condensation reaction, resulting in a high breakdown strength recovery rate of the repaired insulation layer.

[0131] Combining Examples 2 and 4-9, and referring to Table 3, it can be seen that the cable made of the insulating material in Example 2, after being connected to a 1kV circuit and subjected to an aging test under ultraviolet irradiation, exhibits greater tensile strength retention rate and tensile breaking strength retention rate than that in Examples 4-9. This may be because the ratio of bromocresol purple to hydroxyl-terminated polydimethylsiloxane, and the ratio of toluene diisocyanate to hydroxyl-terminated polybutadiene, affect the anti-aging properties of the material, with the ratio in Example 2 being more optimal.

[0132] Combining Examples 2 and 11-12, and referring to Table 2, it can be seen that the cable made of the insulating material in Example 11, after being connected to a 1kV circuit and subjected to aging tests under ultraviolet irradiation, exhibited greater tensile strength retention rate and tensile breaking strength retention rate than both Examples 2 and 11. This indicates that the surface functionalization treatment of titanium dioxide sol can further improve the anti-aging performance of the material. This may be because it significantly delays the photodegradation of bromocresol purple and siloxane self-healing agents, thus extending the effective lifespan of the microcapsules in outdoor environments. Simultaneously, the photocatalytic activity of titanium dioxide can also decompose trace amounts of oxygen and free radicals encountered, reducing the risk of core material oxidation.

[0133] 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. A weather-resistant low-voltage cable, comprising a conductor, an insulation layer, a shielding layer, and a protective layer, characterized in that, The insulating layer comprises the following raw materials in parts by weight: 100-150 parts thermoplastic polyurethane, 1-2 parts light stabilizer system, 2-4 parts environmentally responsive microcapsules, 1.5-2.5 parts fumed silica, 11-16 parts flame retardant, and 0.5-0.7 parts processing aid. The environmentally responsive microcapsules use polyurethane as the wall material and bromocresol purple and siloxane self-healing agent as the core material. The method for preparing the environmentally responsive microcapsules is as follows: 1) Weather-resistant low-voltage cables The solution used bromocresol purple and polyvinyl alcohol as the inner aqueous phase, hydroxyl-terminated polydimethylsiloxane and dibutyltin dilaurate as the oil phase, and polyvinyl alcohol solution as the outer aqueous phase. The internal aqueous phase is dispersed in the oil phase to form a W / O primary emulsion. The primary emulsion is then injected into the external aqueous phase and sheared to form a W / O / W emulsion. 2) Interfacial polymerization forms wall material Hydroxyl-terminated polybutadiene was mixed with a chain extender and pre-dispersed in a W / O / W emulsion. Then, a toluene diisocyanate solution was injected, and the mixture was reacted at 54-56℃ for 175-185 min to obtain microcapsules.

2. The weather-resistant low-voltage cable according to claim 1, characterized in that, The weight ratio of bromocresol purple to hydroxyl-terminated polydimethylsiloxane is 1:(80-90).

3. The weather-resistant low-voltage cable according to claim 1, characterized in that, The toluene diisocyanate solution is obtained by dissolving toluene diisocyanate in a solvent, and the weight ratio of toluene diisocyanate to hydroxyl-terminated polybutadiene is (1.4-1.5):

1.

4. A weather-resistant low-voltage cable according to claim 1, characterized in that, The droplet size of the W / O / W emulsion is 8-12 μm.

5. A weather-resistant low-voltage cable according to claim 1, characterized in that, The injection rate of the toluene diisocyanate solution is 1 mL / min·L.

6. A weather-resistant low-voltage cable according to claim 1, characterized in that, The method for preparing the environmentally responsive microcapsules further includes: 3) Surface functionalization treatment The microcapsules were immersed in titanium dioxide sol and dried at 60°C to form a 0.2 μm thick protective layer; then the surface was treated with a silane coupling agent.

7. A weather-resistant low-voltage cable according to claim 1, characterized in that, The light stabilizer system is a benzotriazole and tetramethylpiperidine derivative coated with a nano-SiO2 carrier.

8. A method for preparing a weather-resistant low-voltage cable as described in any one of claims 1-7, characterized in that, Includes the following steps: By sequentially wrapping the conductor with an insulation layer, a shielding layer, and a protective layer, a weather-resistant low-voltage cable is obtained.

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