Weather-proof low-voltage cable and preparation method thereof

Abstract

The invention relates to the field of cables, in particular to a weather-proof low-voltage cable and a preparation method thereof. The invention discloses a weather-resistant low-voltage cable and a preparation method thereof, the weather-resistant low-voltage cable comprises a conductor, an insulating layer, a shielding layer and a protective layer, the insulating layer comprises the following raw materials in parts by weight: 100-150 parts of thermoplastic polyurethane, 1-2 parts of a light stabilization system, 2-4 parts of environmental response microcapsules, 1.5-2.5 parts of fumed silica, 11-16 parts of a flame retardant and 0.5-0.7 part of a processing aid; the environment response microcapsule takes polyurethane as a wall material and bromocresol purple and a siloxane self-repairing agent as core materials. According to the cable, free radicals initiated by ultraviolet rays are captured through a light stabilization system, oxidative degradation of matrix resin is inhibited, and the service life of the cable in outdoor ultraviolet and high and low temperature alternating environments is prolonged. And meanwhile, the environment response microcapsules are added, so that the aged and cracked insulating layer is continuously repaired in time, and the anti-aging effect of the cable is greatly improved.

Description

Technical Field

[0001] The present application relates to the field of cables, and in particular to a weather-resistant low-voltage cable and a preparation method thereof. Background Art

[0002] A cable is a conductor covered with insulation, protective layers, and shielding layers, used to transmit power or signal current or voltage. It can be categorized by voltage as either high-voltage or low-voltage. While low-voltage cable lines are more expensive and more difficult to install and maintain than low-voltage overhead lines or low-voltage insulated overhead lines, they are widely used in low-voltage power distribution systems due to their reliability, lack of poles, lack of floor space, unobstructed appearance, and minimal impact from external influences.

[0003] The insulation layer of low-voltage cables is typically made of cross-linked polyethylene (XLPE). While XLPE offers many advantages, it also faces aging issues due to physical and chemical factors. Current loads in cables generate significant heat, accelerating the movement of molecules within the insulation layer and generating complex physical and chemical reactions, which can lead to a gradual weakening of the insulation's crosslinking and insulation properties.

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

[0005] Regarding the above-mentioned related technologies, the applicant believes that commonly used anti-aging additives are generally organic additives, which are prone to migration and precipitation in the insulating material under the combined action of high temperature and current during high-voltage current load operation, resulting in their inability to exert their effects for a long time. Summary of the Invention

[0006] In order to improve the weather resistance of low-voltage cables, the present application provides a weather-resistant low-voltage cable and a preparation method thereof.

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

[0008] A weather-resistant low-voltage cable and a preparation method thereof, comprising a conductor, an insulating layer, a shielding layer, and a protective layer. The insulating layer comprises the following raw materials in parts by weight: 100-150 parts of thermoplastic polyurethane, 1-2 parts of a light stabilization system, 2-4 parts of environmentally 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.

[0009] The environmental response microcapsules use polyurethane as the wall material and bromocresol purple and silicone self-healing agent as the core material.

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

[0011] The microcapsules of the polyurethane wall material encapsulate bromocresol purple and silicone self-healing agents. When the insulating layer produces acidic peroxides due to aging, the discoloration of bromocresol purple triggers the rupture of the microcapsules. The released silicone self-healing agents can cross-link into a film at the microcracks, actively repairing the damage and preventing further expansion of aging.

[0012] Siloxane self-healing agent has low surface energy and fluidity. When cracks appear in the insulating layer 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 insulation layer has a high breakdown strength recovery rate.

[0013] Bromocresol purple is used as a pH indicator. In the acidic environment at the early stage of insulation aging, it changes from purple to yellow. The degree of cable aging can be visually judged by the change in appearance color, which facilitates early maintenance and replacement, reducing the risk of sudden failures.

[0014] Nano-scale fumed silica is evenly dispersed in the matrix resin to form "physical cross-linking points", which increases the tensile strength and elongation at break of the insulation layer, while reducing the risk of cracking due to thermal expansion and contraction.

[0015] Furthermore, the preparation method of the environmental responsive microcapsules is:

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

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

[0018] The inner aqueous phase is dispersed in the oil phase to form W / O colostrum, and the colostrum is injected into the outer aqueous phase and sheared to form a W / O / W emulsion;

[0019] 2) Interfacial polymerization to form wall materials

[0020] The terminal hydroxyl polybutadiene is mixed with a chain extender and pre-dispersed in a W / O / W emulsion, and then a toluene diisocyanate solution is injected and reacted at 54-56°C for 175-185 minutes to obtain microcapsules.

[0021] By adopting the above technical solution, the inner water phase is wrapped by the oil phase and then coated by the polyurethane wall material to form a "water-oil-water" three-layer structure. This design allows the bromocresol purple and the silicone self-healing agent to be stored in isolation, avoiding premature reaction between the two and extending the service life of the microcapsules.

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

[0023] The dibutyltin dilaurate in the obtained microcapsules serves as a siloxane cross-linking catalyst, is encapsulated in the oil phase and is in direct contact with the siloxane, thereby improving the catalytic efficiency and the repair speed; the low surface energy of the hydroxyl-terminated polydimethylsiloxane enables it to spread quickly at the microcracks, and the volume resistivity recovery rate of the insulating layer after repair is improved.

[0024] When the external environment changes, such as acidic penetration, the PVA film dissolves under acidic conditions, triggering the color change of bromocresol purple and the release of siloxane, achieving a precise response. The conjugated double bond structure of hydroxy-terminated polybutadiene introduced into the polyurethane wall material absorbs some ultraviolet light (290-400nm), reducing the photodegradation of bromocresol purple and extending the 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 maintains an appropriate concentration in the microcapsules. This can not only sensitively sense the acidic environment caused by the aging of the insulation layer and provide a timely color change warning, but also prevent the stability of the microcapsules from being 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 tiny cracks in the insulation layer, thereby improving the self-healing efficiency and significantly enhancing 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, so that the microcapsules maintain stable structure and performance during cable processing and long-term use, extending the service life and ensuring long-term stable operation of the cable.

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

[0029] By employing this technical solution, a 1.4-1.5:1 ratio ensures sufficient crosslinking of the polyurethane segments, forming a three-dimensional network structure and increasing the crosslink density compared to traditional ratios. A moderate excess of TDI promotes the formation of urethane bonds (NHCOO) and urea bonds (NHCONH), reducing microporous defects in the wall material, lowering oxygen and water vapor transmission rates, and slowing core material aging.

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

[0031] By adjusting the cross-linking density, the wall material begins to slowly degrade when the pH is less than 6.0 or the temperature is greater than 70°C, which is highly matched with the color change threshold of bromocresol purple (pH 5.5-6.5), thus achieving "perception-response" integration.

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

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

[0034] By employing this 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, preventing sudden polymerization caused by localized excessive isocyanate concentrations. The cross-linking reaction rate is controlled at 0.2-0.3 mol / (L·h), forming a uniform polyurethane elastomer network. The uniform injection rate of the TDI solution creates a uniform shear field, reducing the average microcapsule particle size, lowering the monodispersity coefficient, and improving sphericity, all of which facilitates uniform dispersion within the insulation layer.

[0035] Slow injection promotes the formation of flexible segments with high -NHCOO content on the inner side of the wall material (close to 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 further comprises:

[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 this technical solution, the protective layer formed by the titanium dioxide sol effectively shields ultraviolet light from 290-400nm, achieving a UV blockage rate exceeding 95%. This significantly slows the photodegradation of bromocresol purple and the silicone self-healing agent, extending the effective lifespan of the microcapsules in outdoor environments. Furthermore, the titanium dioxide's photocatalytic activity decomposes trace amounts of oxygen and free radicals it encounters, reducing the risk of core material oxidation. The titanium dioxide coating exhibits excellent chemical inertness, reducing the swelling rate of the microcapsule wall in acidic and alkaline environments (pH 3-11), preventing the penetration of corrosive media and ensuring the stability of the core material.

[0040] The silane coupling agent forms an organic-inorganic transition layer on the microcapsule surface. One end undergoes a condensation reaction with the hydroxyl groups of the titanium dioxide coating, while the organic group at the other end forms an entanglement and physical adsorption with the matrix resin, enhancing the interfacial bond strength between the microcapsules and the matrix, effectively preventing microcapsule shedding or agglomeration during processing and use. After surface treatment, the surface energy of the microcapsules is reduced, more closely matching that of the matrix. This improves the uniformity of dispersion within the insulating layer, avoiding uneven performance issues caused by localized high concentrations.

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

[0042] By employing this technical solution, benzotriazole effectively absorbs UV rays in the 290-400nm range, while tetramethylpiperidine derivatives capture free radicals generated by UV radiation. The combination of the two forms a dual "absorption-scavenging" protection mechanism, enhancing UV rejection and free radical scavenging efficiency. The high surface area and nanoscale size (10-50nm) of the nano-SiO2 carrier ensures uniform dispersion of the light stabilizer within the matrix resin, preventing agglomeration. Furthermore, the inorganic network structure of the SiO2 prevents the light stabilizer from migrating or precipitating in high-temperature and high-humidity environments, improving its effective retention in the insulating layer and prolonging the light stabilization effect.

[0043] Nano-SiO2 carriers can act as physical reinforcing fillers and work synergistically with fumed silica to increase the tensile strength of the insulating layer.

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

[0045] In a second aspect, the present application provides a method for preparing a weather-resistant low-voltage cable, which adopts the following technical solution.

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

[0047] The insulation layer, shielding layer and protective layer are wrapped around the conductor in sequence to obtain a weather-resistant low-voltage cable.

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

[0049] This application captures ultraviolet-induced free radicals through a light stabilization system, inhibits the oxidative degradation of the matrix resin, and extends the service life of the cable in outdoor ultraviolet, high and low temperature alternating environments. At the same time, environmentally responsive microcapsules are added, and the microcapsules of the polyurethane wall material encapsulate bromocresol purple and silicone self-repairing agents. When the insulating layer produces acidic peroxides due to aging, the discoloration of bromocresol purple triggers the rupture of the microcapsules. The released silicone self-repairing agent can cross-link into a film at the microcracks, actively repair the damage, and prevent further expansion of aging. When cracks are generated in the insulating layer due to aging, the repair agent can quickly migrate to the damaged area and form an elastic network through a hydroxyl condensation reaction. The insulation layer has a high breakdown strength recovery rate after repair. DETAILED DESCRIPTION

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

[0051] Preparation examples of raw materials and intermediates

[0052] raw material

[0053] The raw materials of the examples of this application can be obtained from the market:

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

[0055] Nano-SiO2 carrier-coated benzotriazole, particle size 80nm;

[0056] Tetramethylpiperidine derivatives, molecular weight > 2000;

[0057] Fumed silica, hydrophobic type;

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

[0059] Processing aid, 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, alcoholysis degree 88%;

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

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

[0064] Nanomolecular sieve (3Å), preactivated at 200 °C for 2 h;

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

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

[0067] Chain extender, ethylenediamine, is used as a 10% aqueous solution;

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

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

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

[0071] Silane coupling agent, KH550, is used in the form of a 1% alcohol solution.

[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 cable

[0076] According to the raw material ratio in Table 1, a mixture of deionized water, bromocresol purple, and polyvinyl alcohol was used as the inner aqueous phase, a mixture of hydroxyl-terminated polydimethylsiloxane, dibutyltin dilaurate, nanomolecular sieves, and cyclohexane was used as the oil phase, and a mixture of deionized water, polyvinyl alcohol, and sodium lauryl sulfate was used as the outer aqueous phase;

[0077] The inner aqueous phase was dispersed in the oil phase at a speed of 10,000 rpm to form W / O colostrum, which was then injected into the outer 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 to form wall materials

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

[0080] Table 1 Raw material ratios for Preparation Examples 1-7 (kg)

[0081]

[0082] Preparation Example 8

[0083] Different from Preparation Example 1, the injection rate of the toluene diisocyanate solution in Preparation Example 8 is 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 cable

[0087] According to the raw material ratio of Preparation Example 1 in Table 1, a mixture of deionized water, bromocresol purple, and polyvinyl alcohol was used as the inner aqueous phase, a mixture of hydroxyl-terminated polydimethylsiloxane, dibutyltin dilaurate, nanomolecular sieves, and cyclohexane was used as the oil phase, and a mixture of deionized water, polyvinyl alcohol, and sodium lauryl sulfate was used as the outer aqueous phase;

[0088] The inner aqueous phase was dispersed in the oil phase at a speed of 10,000 rpm to form W / O colostrum, which was then injected into the outer 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 to form wall materials

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

[0091] 3) Surface functionalization treatment

[0092] The 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] The samples were washed three times by alternating centrifugation with ethanol / water, and then freeze-dried at -40 °C for 24 h and then dried under vacuum at 25 °C.

[0095] Preparation Example 10

[0096] Different from Preparation Example 9, in Preparation Example 10, 3) surface functionalization treatment

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

[0098] The samples were washed three times by alternating centrifugation with ethanol / water, and then freeze-dried at -40 °C for 24 h and then dried under vacuum at 25 °C.

[0099] Example

[0100] Examples 1-3

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

[0102] S1. Insulation wrap

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

[0104] 2. Cool down to 110°C, add environmental responsive microcapsules, and stir at 150 rpm for 10 minutes to break them;

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

[0106] 4. Add the mixed material to the screw extruder and extrude it through the die to coat the conductor surface to form an insulating layer. The extrusion process parameters are as follows: extruder temperature: feeding section 90-100°C, compression section 110-120°C, homogenization section 120-130°C, die section 125-135°C, screw speed 40-60 rpm, cooling method: water cooling, water temperature 20-30°C;

[0107] S2. Wrap shielding layer

[0108] Wrap the aluminum foil shield over the insulation;

[0109] S3. Wrapping protective layer

[0110] Wrap the polyethylene protective layer over the shielding layer.

[0111] Table 2 Raw material ratios 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 a tetramethylpiperidine derivative in a weight ratio of 3:2; and the environmentally responsive microcapsules are from Preparation Example 1.

[0114] Examples 4-12

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

[0116] Comparative Example

[0117] Comparative Example 1

[0118] The difference from Example 1 is that in Comparative Example 1, an equal amount of matrix resin is used to replace the environment-corresponding microcapsules.

[0119] Performance testing

[0120] According to the method in S1 of the embodiment and comparative example, the insulating material was prepared without wrapping during extrusion, and the following performance tests were performed. The test results are shown in Table 3.

[0121] Mechanical properties: With reference to "General test methods for insulation and sheathing materials of electric and optical cables Part 11: General test methods for thickness and dimensions - Mechanical properties tests" GB / T2951.11-2008, the tensile strength and elongation at break of the protective sheaths obtained in the examples and comparative examples were tested.

[0122] Aging test: The cables obtained in Example and Comparative Example S1 were used. The cross section of the cables was 1000 mm. 2 , connect the cable to a 1kV circuit, and then refer to the "Plastics Laboratory Light Source Exposure Test Method Part 3: Fluorescent UV Lamp" GB-T16422.3-2022, use a combination of four UV lamps to perform UV aging, and assist with high-temperature aging at 60°C. After aging for 25 days, peel off the protective cover and perform tensile strength and elongation at break tests again;

[0123] Calculate the aging retention rate:

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

[0125] Aging retention rate of breaking strength = breaking strength after aging / breaking strength before aging × 100%.

[0126] Table 3 Performance test results

[0127]

[0128] Combining Examples 1-12 with Comparative Example 1 and Table 3, it can be seen that the cables made of the insulating materials in Examples 1-12 were connected to a 1kV circuit and then subjected to an aging test under ultraviolet irradiation. The aging retention rate of the tensile strength and the tensile retention rate of the breaking strength were both greater than those in Comparative Example 1, which indicates that the insulating material prepared in the present application has better aging resistance.

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

[0130] In combination with Example 2 and Example 4, and in combination with Table 2, it can be seen that the cable made of the insulating material in Example 4 was connected to a 1kv circuit and then subjected to an aging test under ultraviolet irradiation. Its tensile strength aging retention rate and breaking strength tensile retention rate were both greater than those in Example 2, which shows that the addition of thermally conductive fillers can further improve the aging resistance of the insulating material. This may be because the microcapsules of the polyurethane wall material encapsulate bromocresol purple and silicone self-repairing agents. When the insulating layer produces acidic substances due to aging, the discoloration of bromocresol purple triggers the rupture of the microcapsules. The released silicone self-repairing agents can cross-link into films at the microcracks, actively repair damage, and prevent further expansion of aging. When cracks occur in the insulating layer, the repairing agent can quickly migrate to the damaged area, form an elastic network through a hydroxyl condensation reaction, and the breakdown strength recovery rate of the insulating layer after repair is high.

[0131] Combining Example 2 with Examples 4-9 and Table 3, it can be seen that the cable made of the insulating material in Example 2 was connected to a 1kV circuit and then subjected to an aging test under ultraviolet irradiation, and its tensile strength aging retention rate and breaking strength tensile retention rate were both greater than those of Examples 4-9. This may be because the ratio of bromocresol purple to hydroxyl-terminated polydimethylsiloxane, and the ratio of toluene diisocyanate to terminal hydroxyl polybutadiene have an impact on the aging resistance of the material, among which the ratio in Example 2 is better.

[0132] Combining Example 2 with Examples 11-12 and Table 2, it can be seen that the cable made from the insulating material of Example 11, after being connected to a 1kV circuit and subjected to aging tests under UV irradiation, exhibited greater aging retention of tensile strength and tensile strength at break than both Examples 2 and 11. This demonstrates that surface functionalization of the titanium dioxide sol further enhances the material's aging resistance. This is likely due to the delayed photodegradation of bromocresol purple and the silicone self-healing agent, extending the effective lifespan of the microcapsules in outdoor environments. Furthermore, the photocatalytic activity of titanium dioxide can decompose trace amounts of oxygen and free radicals it comes into contact with, reducing the risk of core material oxidation.

[0133] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A weather-resistant low-voltage cable, comprising a conductor, an insulating 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 of thermoplastic polyurethane, 1-2 parts of light stabilization system, 2-4 parts of environmental response microcapsules, 1.5-2.5 parts of fumed silica, 11-16 parts of flame retardant, and 0.5-0.7 parts of processing aid; The environmental response microcapsules use polyurethane as the wall material and bromocresol purple and silicone self-healing agent as the core material.

2. A weather-resistant low-voltage cable according to claim 1, characterized in that: The preparation method of the environmental responsive microcapsules is as follows: 1) Weather-resistant low-voltage cable Bromocresol purple and polyvinyl alcohol are used as the inner aqueous phase, hydroxyl-terminated polydimethylsiloxane and dibutyltin dilaurate are used as the oil phase, and polyvinyl alcohol solution is used as the outer aqueous phase. The inner aqueous phase is dispersed in the oil phase to form W / O colostrum, and the colostrum is injected into the outer aqueous phase and sheared to form a W / O / W emulsion; 2) Interfacial polymerization to form wall materials The terminal hydroxyl polybutadiene is mixed with a chain extender and pre-dispersed in a W / O / W emulsion, and then a toluene diisocyanate solution is injected and reacted at 54-56°C for 175-185 minutes to obtain microcapsules.

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

4. A weather-resistant low-voltage cable according to claim 2, characterized in that: The weight ratio of the toluene diisocyanate to the hydroxyl-terminated polybutadiene is (1.4-1.5):

1.

5. The weather-resistant low-voltage cable according to claim 2, characterized in that: The W / O / W emulsion has a droplet size of 8-12 μm.

6. A weather-resistant low-voltage cable according to claim 2, characterized in that: The injection rate of the toluene diisocyanate solution is 1 mL / min·L.

7. The weather-resistant low-voltage cable according to claim 2, characterized in that: The method for preparing the environmentally responsive microcapsules further comprises: 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.

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

9. The weather-resistant low-voltage cable according to claim 1, characterized in that: The matrix resin is thermoplastic polyurethane.

10. A method for preparing a weather-resistant low-voltage cable according to any one of claims 1 to 9, characterized in that: The following steps are involved: The insulation layer, shielding layer and protective layer are wrapped around the conductor in sequence to obtain a weather-resistant low-voltage cable.

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