Weather-resistance-enhanced photovoltaic cable for high-altitude environment and preparation method of weather-resistance-enhanced photovoltaic cable

Abstract

The invention relates to the technical field of cables, in particular to a weather-resistant reinforced photovoltaic cable for a high-altitude environment and a preparation method of the weather-resistant reinforced photovoltaic cable. The cable comprises a metal conductor, an insulating layer sleeving the metal conductor, and a sheath layer sleeving the insulating layer. The insulating layer is made of a cross-linked polyethylene material; the sheath layer comprises the following components in parts by weight: 50-60 parts of a polybutadiene-polyvinyl chloride block copolymer, 8-12 parts of modified hollow silicon dioxide microspheres, 0.5-2 parts of an anti-aging agent, 5-10 parts of zinc borate and 5-10 parts of calcium stearate. According to the photovoltaic cable, the polybutadiene-polyvinyl chloride segmented copolymer is adopted as the material of the sheath layer, so that the photovoltaic cable has good ultraviolet resistance, the modified hollow silicon dioxide microspheres can improve the thermal insulation performance of the sheath layer, the situation that the photovoltaic cable becomes brittle due to frequent temperature change is avoided, and the service life of the photovoltaic cable is prolonged. Therefore, the adaptability of the photovoltaic cable in a high-altitude area is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable, in particular to a high-altitude environment photovoltaic cable with reinforced weather resistance and a preparation method. BACKGROUND

[0002] The photovoltaic cable is a special cable designed for a solar photovoltaic power generation system, mainly used for connecting solar cell panels, inverters and power grids and other equipment to realize the transmission and conversion of direct current. The photovoltaic cable is generally laid outdoors with the photovoltaic power generation system, which requires the photovoltaic cable to have strong anti-aging performance.

[0003] In order to improve the power generation efficiency, the existing photovoltaic power generation system is often arranged in a high-altitude area of 1000-4500 meters. However, the ultraviolet radiation time is long and the day and night temperature difference is large in the high-altitude area. The existing photovoltaic cable has poor weather resistance, and is affected by sunlight and temperature changes in the high-altitude area for a long time. Aging occurs to different degrees, which damages the insulation or sheath of the cable, and reduces the service life of the photovoltaic cable in the high-altitude area. SUMMARY

[0004] In order to solve the above problems, the present application provides a high-altitude environment photovoltaic cable with reinforced weather resistance and a preparation method.

[0005] The technical scheme of the present application is: a high-altitude environment photovoltaic cable with reinforced weather resistance, comprising a metal conductor, an insulation layer sleeved on the metal conductor, and a sheath layer sleeved on the insulation layer; the insulation layer is a cross-linked polyethylene material; the sheath layer comprises the following components by weight fraction: polybutadiene-polyvinyl chloride block copolymer 50-60 parts, modified hollow silica microspheres 8-12 parts, anti-aging agent 0.5-2 parts, zinc borate 5-10 parts, and calcium stearate 5-10 parts.

[0006] Note: The above photovoltaic cable uses polybutadiene-polyvinyl chloride block copolymer as the sheath layer material, so that the photovoltaic cable has good ultraviolet resistance. The polybutadiene can toughen the polyvinyl chloride, improve the strength and weather resistance of the photovoltaic cable, and the modified hollow silica microspheres can improve the heat preservation performance of the sheath layer, avoiding the brittleness of the photovoltaic cable due to frequent temperature changes, to ensure the adaptability of the photovoltaic cable in high-altitude areas.

[0007] Further, the anti-aging agent is anti-aging agent RD or anti-aging agent ODA.

[0008] Note: The above anti-aging agent can capture free radicals generated during the aging process, delay the aging of the sheath layer, and improve the service life of the anti-aging agent.

[0009] Further, the preparation method of the polybutadiene-polyvinyl chloride block copolymer comprises the following steps: 1) Dissolve the polybutadiene into tetrahydrofuran, then add 3-mercaptopropionic acid and benzophenone, stir for 10-15 min to obtain a first mixture, then stir the mixture under ultraviolet light irradiation for 6-8 h, and then perform vacuum distillation to obtain carboxylated polybutadiene; wherein the mass ratio of polybutadiene, 3-mercaptopropionic acid, benzophenone and tetrahydrofuran is 1:0.2-0.4:0.1-0.15:6-8; 2) Add polyvinylidene fluoride and an aqueous ethylenediamine solution into a reaction kettle, stir for 5-10 min, then add tetrabutylammonium bromide into the reaction kettle, and keep the reaction kettle at a temperature of 150-200°C for 20-48 h, then perform vacuum filtration to obtain a solid powder, and then wash and dry the solid powder to obtain aminated polyvinylidene fluoride; wherein the mass ratio of polyvinylidene fluoride, tetrabutylammonium bromide and the aqueous ethylenediamine solution is 1:0.12-0.18:5-6; 3) Add room-temperature N,N-dimethylformamide into a reaction container, then heat the reaction container, and every time the temperature in the reaction container increases by 15-20°C, add aminated polyvinylidene fluoride into the reaction container, then stop heating and stir, and when the temperature in the reaction container decreases by 5-10°C, add carboxylated polybutadiene into the reaction container, then resume heating until the temperature in the reaction container reaches 70-80°C, add dicyclohexyl carbodiimide and 1-hydroxybenzotriazole into the reaction container, then keep the reaction container at a constant temperature and stir for 7-10 h to obtain a second mixture; wherein the mass ratio of N,N-dimethylformamide, dicyclohexyl carbodiimide and 1-hydroxybenzotriazole is 1:0.05-0.1:0.1-0.2; the single addition amount of aminated polyvinylidene fluoride accounts for 2.5-5% of the mass of N,N-dimethylformamide; and the single addition amount of carboxylated polybutadiene accounts for 1-3% of the mass of N,N-dimethylformamide; 4) Drop the second mixture into anhydrous ethanol at -5-0°C, then filter to obtain a precipitate, and then wash and dry the precipitate to obtain a polybutadiene-polyvinyl chloride block copolymer, wherein the mass ratio of the second mixture and anhydrous ethanol is 1:5-6.

[0010] It is explained that the above preparation method first grafts carboxyl groups to the polybutadiene chain through 3-mercaptopropionic acid, then grafts amino groups to the polyvinylidene fluoride chain through ethylenediamine, and then forms covalent bonds between the carboxylated polybutadiene and the aminated polyvinylidene fluoride through amidation reaction, so that the flexible polybutadiene chain and the rigid polyvinylidene fluoride chain are connected through chemical bonds, and the phase separation of polybutadiene and polyvinylidene fluoride due to poor compatibility is avoided.

[0011] Further, the wavelength of the ultraviolet light is 360-370 nm.

[0012] Description: The wavelength of the ultraviolet light can ensure the reaction rate of 3-mercaptopropionic acid, so that the 3-mercaptopropionic acid can be fully grafted to the polybutadiene chain.

[0013] Further, the mass concentration of the aqueous ethylenediamine solution is 3-5%.

[0014] Description: The concentration of the aqueous ethylenediamine solution can ensure the pH value of the reaction system, so that the reaction can be fully carried out.

[0015] Further, the preparation method of the modified hollow silica microspheres comprises the following steps: 1) The hollow silica microspheres are added into an ethanol solution with a mass concentration of 40-50%, ultrasonic dispersion is carried out for 15-20 min, then γ-aminopropyl triethoxysilane is added, and then the temperature is kept at 70-80℃ for 1-2 h to obtain a dispersion liquid, and then the dispersion liquid is filtered and dried to obtain the pretreated hollow silica microspheres; wherein the mass ratio of the hollow silica microspheres, the γ-aminopropyl triethoxysilane and the ethanol solution is 1:0.1-0.15:8-12; 2) The polyvinyl alcohol is added into deionized water, and stirred until completely dissolved to obtain a polyvinyl alcohol solution, and the pH value of the polyvinyl alcohol solution is adjusted to 5-6 using dilute hydrochloric acid to obtain an acidic polyvinyl alcohol solution; wherein the mass ratio of the polyvinyl alcohol and the deionized water is 1:15-20; 3) The pretreated hollow silica microspheres are added into the acidic polyvinyl alcohol solution, and stirred at 50-60℃ for 20-30 min, and then filtered and dried to obtain the modified hollow silica microspheres; wherein the mass ratio of the pretreated hollow silica microspheres and the acidic polyvinyl alcohol solution is 1:10-15.

[0016] Description: The above method can improve the dispersibility of the hollow silica microspheres and the compatibility of the hollow silica microspheres with the polybutadiene-polyvinyl chloride block copolymer by loading the polyvinyl alcohol on the hollow silica microspheres, so that the modified hollow silica microspheres can be fully dispersed in the sheath layer.

[0017] On the other hand, the application also provides a preparation method of a weather-resistant photovoltaic cable for high-altitude environment, comprising the following steps: S1, a plurality of metal wires are twisted together to obtain a metal conductor, and then the metal conductor is kept at 75-85℃ for 3-5 min to obtain a preheated metal conductor; S2, polyethylene particles and dicumyl peroxide are added into a screw extruder, after melting at 190-200 DEG C, extrusion coating to the preheated metal conductor, to obtain the polyethylene coated metal conductor, then the polyethylene coated metal conductor is crosslinked under nitrogen at 200-210 DEG C for 10-30 min, to obtain the metal conductor with insulating layer; wherein, the amount of dicumyl peroxide added accounts for 1-3% of the mass of polyethylene particles, the thickness of the insulating layer is 5-8 mm; S3, the ingredients of the sheath layer are added into the internal mixer according to the weight parts, mixing at 130-140 DEG C, to obtain the sheath layer material, using the extruder to extrude the sheath layer material to the metal conductor with insulating layer, to obtain the metal conductor with sheath layer, then cooling and setting, to obtain the photovoltaic cable; wherein, the thickness of the sheath layer is 1.5-4 mm.

[0018] Description: the above preparation method is to extrude polyethylene to the metal conductor, then crosslinking at high temperature, to form the insulating layer on the surface of the metal conductor, to ensure the power transmission performance of the photovoltaic cable, then extruding the sheath layer material to the insulating layer, to form the sheath layer after cooling, to improve the impact resistance and weather resistance of the photovoltaic cable.

[0019] The beneficial effects of the present application are: (1) the photovoltaic cable of the present application uses polybutadiene-polyvinyl chloride block copolymer as the sheath layer material, so that the photovoltaic cable has good ultraviolet resistance, and the polybutadiene can toughen the polyvinyl chloride, improve the strength and weather resistance of the photovoltaic cable, and the modified hollow silica microspheres can improve the heat preservation performance of the sheath layer, avoiding the brittleness of the photovoltaic cable due to frequent temperature changes, to ensure the adaptability of the photovoltaic cable in high altitude areas.

[0020] (2) the preparation method of the present application is to extrude polyethylene to the metal conductor, then crosslinking at high temperature, to form the insulating layer on the surface of the metal conductor, to ensure the power transmission performance of the photovoltaic cable, then extruding the sheath layer material to the insulating layer, to form the sheath layer after cooling, to improve the impact resistance and weather resistance of the photovoltaic cable. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is the photovoltaic cable structure schematic diagram of example 1 of the present application; Wherein, 1-metal conductor, 2-insulating layer, 3-sheath layer. DETAILED DESCRIPTION

[0022] In order to further illustrate the way adopted by the present application and the effects obtained, the technical solutions of the present application will be described clearly and completely in combination with experiments.

[0023] Example 1: as Figure 1As shown, a high-altitude environment photovoltaic cable with reinforced weather resistance comprises a metal conductor 1, an insulating layer 2 sleeved on the metal conductor 1, and a sheath layer 3 sleeved on the insulating layer 2; the insulating layer 2 is made of cross-linked polyethylene material; the sheath layer 3 comprises the following components in terms of weight fraction: polybutadiene-polyvinyl chloride block copolymer 55 parts, modified hollow silica microspheres 10 parts, anti-aging agent 1 part, zinc borate 8 parts, and calcium stearate 8 parts; the anti-aging agent is anti-aging agent RD, and the metal conductor is aluminum alloy; The preparation method of the polybutadiene-polyvinyl chloride block copolymer comprises the following steps: 1) Dissolve polybutadiene into tetrahydrofuran, then add 3-mercaptopropionic acid and benzophenone, stir for 12 min to obtain a first mixture, then stir the mixture under the condition of ultraviolet light irradiation of 50 mW / cm² for 7 h, then perform vacuum distillation at a pressure of -0.095 MPa and a temperature of 65°C to obtain carboxylated polybutadiene; wherein the mass ratio of polybutadiene, 3-mercaptopropionic acid, benzophenone and tetrahydrofuran is 1:0.3:0.12:7; the wavelength of the ultraviolet light is 365 nm; 2) Add polyvinylidene fluoride and an ethylenediamine aqueous solution with a mass concentration of 4% into a reaction kettle, stir for 8 min, then add tetrabutylammonium bromide into the reaction kettle, and keep the reaction kettle at a temperature of 180°C for 35 h, then perform vacuum filtration to obtain a solid powder, which is washed and dried to obtain aminated polyvinylidene fluoride; wherein the mass ratio of polyvinylidene fluoride, tetrabutylammonium bromide and the ethylenediamine aqueous solution is 1:0.16:5.5, the drying temperature is 80°C, and the drying time is 2 h; 3) Add room temperature N,N-dimethylformamide into a reaction container, then heat the reaction container, and every time the temperature in the reaction container increases by 18°C during the heating process, add aminated polyvinylidene fluoride into the reaction container, then stop heating and stirring, add carboxylated polybutadiene into the reaction container when the temperature in the reaction container decreases by 8°C, then resume heating until the temperature in the reaction container reaches 75°C, add dicyclohexyl carbodiimide and 1-hydroxybenzotriazole into the reaction container, then keep warm and stir for 8 h to obtain a second mixture; the above room temperature is 25°C; Wherein, the mass ratio of N,N-dimethylformamide, dicyclohexyl carbodiimide and 1-hydroxybenzotriazole is 1:0.08:0.15; the single addition amount of aminated polyvinylidene fluoride accounts for 4% of the mass of N,N-dimethylformamide; the single addition amount of carboxylated polybutadiene accounts for 2% of the mass of N,N-dimethylformamide; 4) drop the second mixed solution into anhydrous ethanol at -2℃, then filter to obtain a precipitate, and after washing and drying the precipitate, a polybutadiene-polyvinyl chloride block copolymer is obtained; wherein the mass ratio of the second mixed solution to anhydrous ethanol is 1:5.5, the drying temperature is 85℃, and the drying time is 1h; The preparation method of the modified hollow silica microspheres comprises the following steps: 1) add the hollow silica microspheres into an ethanol solution with a mass concentration of 45%, ultrasonically disperse for 18 min, then add γ-aminopropyl triethoxysilane, and then incubate at 75℃ for 1.5h to obtain a dispersion liquid, and then filter and dry the dispersion liquid to obtain the pretreated hollow silica microspheres; wherein the mass ratio of the hollow silica microspheres, γ-aminopropyl triethoxysilane and the ethanol solution is 1:0.12:10, and the ultrasonic dispersion power is 500W; 2) add polyvinyl alcohol into deionized water, stir until completely dissolved to obtain a polyvinyl alcohol solution, adjust the pH value of the polyvinyl alcohol solution to 5.5 using dilute hydrochloric acid to obtain an acidic polyvinyl alcohol solution; wherein the mass ratio of polyvinyl alcohol to deionized water is 1:18; 3) add the pretreated hollow silica microspheres into the acidic polyvinyl alcohol solution, stir at 55℃ and a stirring speed of 300r / min for 25 min, and then filter and dry to obtain the modified hollow silica microspheres; wherein the mass ratio of the pretreated hollow silica microspheres to the acidic polyvinyl alcohol solution is 1:12; The preparation method of the above-mentioned high-altitude environment photovoltaic cable with reinforced weather resistance comprises the following steps: S1, seven metal wires are twisted together to obtain a metal conductor 1, and then the metal conductor 1 is incubated at 80℃ for 4 min to obtain a preheated metal conductor; S2, polyethylene particles and dicumyl peroxide are added into a screw extruder, melted at 195℃, and then extruded to coat on the preheated metal conductor to obtain a polyethylene coated metal conductor, and then the polyethylene coated metal conductor is crosslinked under nitrogen at 205℃ for 20 min to obtain a metal conductor coated with an insulating layer; wherein the amount of dicumyl peroxide added accounts for 2% of the mass of the polyethylene particles, and the thickness of the insulating layer is 6mm; S3, the components of the sheath layer 3 are added into an internal mixer in parts by weight, and mixing is carried out at 135℃ to obtain a sheath layer material, the sheath layer material is extruded to coat on the metal conductor coated with the insulating layer using an extruder to obtain a metal conductor coated with a sheath layer, and then cooling and setting to obtain a photovoltaic cable; wherein the thickness of the sheath layer is 2mm.

[0024] Example 2: This example is basically the same as Example 1, except that the sheath layer comprises the following components in parts by weight: polybutadiene-polyvinyl chloride block copolymer 50 parts, modified hollow silica microspheres 8 parts, antioxidant 0.5 part, zinc borate 5 parts, calcium stearate 5 parts.

[0025] Example 3: This example is basically the same as Example 1, except that the sheath layer comprises the following components in parts by weight: polybutadiene-polyvinyl chloride block copolymer 60 parts, modified hollow silica microspheres 12 parts, antioxidant 2 parts, zinc borate 10 parts, calcium stearate 10 parts.

[0026] Example 4: This example is basically the same as Example 1, except that the mass ratio of polybutadiene, 3-mercaptopropionic acid, benzophenone and tetrahydrofuran is 1:0.2:0.1:6.

[0027] Example 5: This example is basically the same as Example 1, except that the mass ratio of polybutadiene, 3-mercaptopropionic acid, benzophenone and tetrahydrofuran is 1:0.4:0.15:8.

[0028] Example 6: This example is basically the same as Example 1, except that the mass ratio of polyvinylidene fluoride, tetrabutylammonium bromide and ethylenediamine aqueous solution is 1:0.12:5.

[0029] Example 7: This example is basically the same as Example 1, except that the mass ratio of polyvinylidene fluoride, tetrabutylammonium bromide and ethylenediamine aqueous solution is 1:0.18:6.

[0030] Example 8: This example is basically the same as Example 1, except that during the heating process, every time the temperature in the reaction vessel increases by 15°C, aminated polyvinylidene fluoride is added to the reaction vessel, then heating is stopped and stirring is performed, and after the temperature in the reaction vessel drops by 5°C, carboxylated polybutadiene is added to the reaction vessel, until the temperature in the reaction vessel reaches 70°C.

[0031] Example 9: This example is basically the same as Example 1, except that during the heating process, every time the temperature in the reaction vessel increases by 20°C, aminated polyvinylidene fluoride is added to the reaction vessel, then heating is stopped and stirring is performed, and after the temperature in the reaction vessel drops by 10°C, carboxylated polybutadiene is added to the reaction vessel, until the temperature in the reaction vessel reaches 80°C.

[0032] Example 10: This example is basically the same as Example 1, except that the single addition amount of aminated polyvinylidene fluoride accounts for 2.5% of the mass of N,N-dimethylformamide.

[0033] Example 11: This example is essentially the same as Example 1 except that the single addition amount of the aminated polyvinylidene fluoride is 5% by mass of the N,N-dimethylformamide.

[0034] Example 12: This example is essentially the same as Example 1 except that the single addition amount of the carboxylated polybutadiene is 1% by mass of the N,N-dimethylformamide.

[0035] Example 13: This example is essentially the same as Example 1 except that the single addition amount of the carboxylated polybutadiene is 3% by mass of the N,N-dimethylformamide.

[0036] Example 14: This example is essentially the same as Example 1 except that the mass ratio of the hollow silica microspheres, the γ-aminopropyl triethoxysilane and the ethanol solution is 1:0.1:8.

[0037] Example 15: This example is essentially the same as Example 1 except that the mass ratio of the hollow silica microspheres, the γ-aminopropyl triethoxysilane and the ethanol solution is 1:0.15:12.

[0038] Example 16: This example is essentially the same as Example 1 except that the mass ratio of the pretreated hollow silica microspheres and the acidic polyvinyl alcohol solution is 1:10.

[0039] Example 17: This example is essentially the same as Example 1 except that the mass ratio of the pretreated hollow silica microspheres and the acidic polyvinyl alcohol solution is 1:15.

[0040] Example 18: This example is essentially the same as Example 1 except that the jacket layer ingredients are added to the internal mixer in parts by mass and mixing is carried out at 130°C to obtain the jacket layer material.

[0041] Example 19: This example is essentially the same as Example 1 except that the jacket layer ingredients are added to the internal mixer in parts by mass and mixing is carried out at 140°C to obtain the jacket layer material.

[0042] Comparative Example 1: With reference to Example 1, the polybutadiene-polyvinyl chloride block copolymer is replaced by a mixture of polybutadiene and polyvinyl chloride.

[0043] Comparative Example 2: With reference to Example 1, the modified hollow silica microspheres are replaced by unmodified hollow silica microspheres.

[0044] Comparative Example 3: With reference to Example 1, the aminated polyvinylidene fluoride is replaced by polyvinylidene fluoride.

[0045] Comparative Example 4: With reference to Example 1, the carboxylated polybutadiene was replaced by polybutadiene.

[0046] Comparative Example 5: With reference to Example 1, the aminoated polyvinylidene fluoride and the carboxylated polybutadiene were added into the reaction vessel at one time.

[0047] Experimental Example: In order to explore the influence of the parameters of each example on the performance of the photovoltaic cable, the insulation resistance of the photovoltaic cable of each example was tested, and then the photovoltaic cable prepared in each example was subjected to 56 cycles of wet and hot alternation. The process of each wet and hot alternation cycle was as follows: first, the photovoltaic cable was kept in an environment of 55°C and 85% relative humidity for 16 hours, and then the photovoltaic cable was kept in an environment of -10°C and 30% relative humidity for 8 hours. After the completion of the wet and hot alternation cycle, the insulation resistance reduction rate of the photovoltaic cable of each example was tested, and the specific exploration was as follows: Experimental Example 1: Exploration of the influence of the sheath layer composition on the performance of the photovoltaic cable With Examples 1-3 and Comparative Examples 1 and 2 as experimental comparisons, the performance of the photovoltaic cable under different sheath layer compositions was as shown in Table 1: Table 1: Performance of photovoltaic cable under different sheath layer compositions

[0048] From the data in Table 1, it can be seen that Examples 1, 2 and 3 are compared: the insulation resistance of the photovoltaic cable of Example 1 is the highest, and the insulation resistance reduction rate is the lowest, indicating that the weather resistance of the photovoltaic cable of Example 1 is the best. This may be because the sheath layer structure of Example 1 is the most compact among the selected sheath layer compositions, so the sheath layer composition selected in Example 1 is the best.

[0049] Example 1 vs. Comparative Example 1: After replacing the polybutadiene-polyvinyl chloride block copolymer with a mixture of polybutadiene and polyvinyl chloride, the insulation resistance reduction rate of the photovoltaic cable increased significantly. This may be because polybutadiene and polyvinyl chloride are not well compatible, so the sheath layer composition selected in Example 1 is better.

[0050] Example 1 vs. Comparative Example 2: After replacing the modified hollow silica microspheres with unmodified hollow silica microspheres, the insulation resistance reduction rate of the photovoltaic cable increased. This may be because the unmodified hollow silica microspheres are not well compatible with the sheath layer, so the sheath layer composition selected in Example 1 is better.

[0051] Experimental Example 2: Exploration of the influence of the preparation parameters of polybutadiene-polyvinyl chloride block copolymer on the performance of the photovoltaic cable With Examples 1, 4-13 and Comparative Examples 3-4 as experimental comparisons, the performance of the photovoltaic cable under different preparation parameters of polybutadiene-polyvinyl chloride block copolymer was as shown in Table 2: Table 2 Photovoltaic cable performance of polybutadiene-polyvinyl chloride block copolymer under different preparation parameters

[0052] From the data in Table 2, it can be seen that: compared with Examples 1, 4 and 5, the insulation resistance of the photovoltaic cable of Example 1 is the highest, and the insulation resistance reduction rate is the lowest, indicating that the weather resistance of the photovoltaic cable of Example 1 is the best. This may be because, under the selected composition of the first mixed solution of Example 1, the carboxyl groups can be fully grafted on the polybutadiene chain, so the composition of the first mixed solution selected in Example 1 is optimal. Compared with Examples 1, 6 and 7, the insulation resistance of the photovoltaic cable of Example 1 is the highest, and the insulation resistance reduction rate is the lowest, indicating that the weather resistance of the photovoltaic cable of Example 1 is the best. This may be because, under the selected ratio of polyvinylidene fluoride and ethylenediamine aqueous solution of Example 1, the amino groups can be fully grafted on the polyvinylidene fluoride chain, so the ratio of polyvinylidene fluoride and ethylenediamine aqueous solution selected in Example 1 is optimal. Compared with Examples 1, 8 and 9, the insulation resistance of the photovoltaic cable of Example 1 is the highest, and the insulation resistance reduction rate is the lowest, indicating that the weather resistance of the photovoltaic cable of Example 1 is the best. This may be because, under the selected reaction vessel temperature of Example 1, the aminoated polyvinylidene fluoride and the carboxylated polybutadiene can be well compatible and fully reacted, so the reaction vessel temperature selected in Example 1 is optimal. Compared with Examples 1, 10, 11, 12 and 13, the insulation resistance of the photovoltaic cable of Example 1 is the highest, and the insulation resistance reduction rate is the lowest, indicating that the weather resistance of the photovoltaic cable of Example 1 is the best. This may be because, under the selected addition amount of aminoated polyvinylidene fluoride and carboxylated polybutadiene of Example 1, the aminoated polyvinylidene fluoride and the carboxylated polybutadiene can be fully reacted, so the addition amount of aminoated polyvinylidene fluoride and carboxylated polybutadiene selected in Example 1 is optimal. Compared with Examples 1 and Comparative Examples 3 and 4, after replacing the aminoated polyvinylidene fluoride with polyvinylidene fluoride or replacing the carboxylated polybutadiene with polybutadiene, the insulation resistance reduction rate of the photovoltaic cable increases, which may be because the polyvinylidene fluoride and the polybutadiene cannot be well compatible, so the preparation method of the polybutadiene-polyvinyl chloride block copolymer selected in Example 1 is more optimal. Compared with Example 1 and Comparative Example 5, after adding the aminoated polyvinylidene fluoride and the carboxylated polybutadiene into the reaction vessel at one time, the insulation resistance reduction rate of the photovoltaic cable increases, which may be because the aminoated polyvinylidene fluoride and the carboxylated polybutadiene cannot be fully combined, so the preparation method of the polybutadiene-polyvinyl chloride block copolymer selected in Example 1 is more optimal.

[0053] Experimental Example 3, Influence of modified hollow silica microsphere preparation parameters on the performance of photovoltaic cable With example 1, 14~17 and comparative example 5 as experimental comparison, the photovoltaic cable performance of modified hollow silica microspheres under different preparation parameters is shown in Table 3 as follows: Table 3 Photovoltaic cable performance of modified hollow silica microspheres under different preparation parameters

[0054] From the data in Table 3, compared with examples 1, 14 and 15: the photovoltaic cable of example 1 has the highest insulation resistance and the lowest insulation resistance drop rate, indicating that the weather resistance of the photovoltaic cable of example 1 is the best. This may be because the hollow silica microspheres selected by example 1 have the most active sites on the surface under the composition of the dispersion liquid, so the composition of the dispersion liquid selected by example 1 is the best. Compared with examples 1, 16 and 17: the photovoltaic cable of example 1 has the highest insulation resistance and the lowest insulation resistance drop rate, indicating that the weather resistance of the photovoltaic cable of example 1 is the best. This may be because the hollow silica microspheres selected by example 1 have the most active sites on the surface under the composition of the dispersion liquid, so the composition of the dispersion liquid selected by example 1 is the best.

[0055] Experimental example 4, explore the effect of sheath layer mixing temperature on the performance of photovoltaic cable With example 1, 18~19 as experimental comparison, the photovoltaic cable performance of sheath layer under different mixing temperature is shown in Table 4 as follows: Table 4 Photovoltaic cable performance of sheath layer under different mixing temperature

[0056] From the data in Table 4, compared with examples 1, 18 and 19: the photovoltaic cable of example 1 has the highest insulation resistance and the lowest insulation resistance drop rate, indicating that the weather resistance of the photovoltaic cable of example 1 is the best. This may be because the sheath layer selected by example 1 has the best flowability under the mixing temperature of the sheath layer, so the mixing temperature of the sheath layer selected by example 1 is the best.

Claims

1. A photovoltaic cable for high-altitude environments with enhanced weather resistance, characterized in that, It includes a metal conductor (1), an insulating layer (2) sleeved on the metal conductor (1), and a sheath layer (3) sleeved on the insulating layer (2); the insulating layer (2) is a cross-linked polyethylene material; the sheath layer (3) includes the following components by weight: 50-60 parts of polybutadiene-polyvinyl chloride block copolymer, 8-12 parts of modified hollow silica microspheres, 0.5-2 parts of antioxidant, 5-10 parts of zinc borate, and 5-10 parts of calcium stearate.

2. The photovoltaic cable for high-altitude environments with enhanced weather resistance according to claim 1, characterized in that, The antioxidant is antioxidant RD or antioxidant ODA.

3. The photovoltaic cable for high-altitude environments with enhanced weather resistance according to claim 1, characterized in that, The preparation method of the polybutadiene-polyvinyl chloride block copolymer includes the following steps: 1) Polybutadiene was dissolved in tetrahydrofuran, followed by the addition of 3-mercaptopropionic acid and benzophenone. After stirring for 10-15 min, a first mixture was obtained. The mixture was then stirred under ultraviolet light for 6-8 h, followed by vacuum distillation to obtain carboxylated polybutadiene. The mass ratio of polybutadiene, 3-mercaptopropionic acid, benzophenone and tetrahydrofuran was 1:0.2-0.4:0.1-0.15:6-8. 2) Add polyvinylidene fluoride and ethylenediamine aqueous solution to a reaction vessel, stir for 5-10 min, then add tetrabutylammonium bromide to the reaction vessel, keep the reaction vessel at 150-200℃ for 20-48 h, and then perform vacuum filtration to obtain solid powder. After washing and drying the solid powder, aminated polyvinylidene fluoride is obtained; wherein, the mass ratio of polyvinylidene fluoride, tetrabutylammonium bromide and ethylenediamine aqueous solution is 1:0.12-0.18:5-6; 3) Add room temperature N,N-dimethylformamide to the reaction vessel, and then heat the reaction vessel. During the heating process, add aminated polyvinylidene fluoride to the reaction vessel every time the temperature inside the reaction vessel increases by 15~20℃. Then stop heating and stir. After the temperature inside the reaction vessel drops by 5~10℃, add carboxylated polybutadiene to the reaction vessel. Then resume heating until the temperature inside the reaction vessel reaches 70~80℃. Add dicyclohexylcarbodiimide and 1-hydroxybenzotriazole to the reaction vessel, and then keep warm and stir for 7~10 hours to obtain the second mixture. The mass ratio of N,N-dimethylformamide, dicyclohexylcarbodiimide, and 1-hydroxybenzotriazole is 1:0.05~0.1:0.1~0.2; the single addition amount of aminated polyvinylidene fluoride accounts for 2.5~5% of the mass of N,N-dimethylformamide; and the single addition amount of carboxylated polybutadiene accounts for 1~3% of the mass of N,N-dimethylformamide. 4) The second mixture is added dropwise into anhydrous ethanol at -5~0℃, then filtered to obtain a precipitate. The precipitate is washed and dried to obtain a polybutadiene-polyvinyl chloride block copolymer. The mass ratio of the second mixture to anhydrous ethanol is 1:5~6.

4. The photovoltaic cable for high-altitude environments with enhanced weather resistance according to claim 3, characterized in that, The wavelength of the ultraviolet light is 360~370nm.

5. The photovoltaic cable for high-altitude environments with enhanced weather resistance according to claim 3, characterized in that, The mass concentration of the ethylenediamine aqueous solution is 3-5%.

6. The photovoltaic cable for high-altitude environments with enhanced weather resistance according to claim 1, characterized in that, The preparation method of the modified hollow silica microspheres includes the following steps: 1) Hollow silica microspheres were added to an ethanol solution with a mass concentration of 40-50% and ultrasonically dispersed for 15-20 min. Then, γ-aminopropyltriethoxysilane was added, and the solution was kept at 70-80℃ for 1-2 h to obtain a dispersion. The dispersion was then filtered and dried to obtain pretreated hollow silica microspheres. The mass ratio of hollow silica microspheres, γ-aminopropyltriethoxysilane and ethanol solution was 1:0.1-0.15:8-12. 2) Add polyvinyl alcohol to deionized water and stir until completely dissolved to obtain a polyvinyl alcohol solution. Adjust the pH of the polyvinyl alcohol solution to 5-6 using dilute hydrochloric acid to obtain an acidic polyvinyl alcohol solution. The mass ratio of polyvinyl alcohol to deionized water is 1:15-20. 3) Add the pretreated hollow silica microspheres to an acidic polyvinyl alcohol solution and stir at 50-60℃ for 20-30 min. Then filter and dry to obtain modified hollow silica microspheres. The mass ratio of the pretreated hollow silica microspheres to the acidic polyvinyl alcohol solution is 1:10-15.

7. The method for preparing a photovoltaic cable for high-altitude environments with enhanced weather resistance according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Twist multiple metal wires together to obtain a metal conductor (1), and then keep the metal conductor (1) at 75~85℃ for 3~5 minutes to obtain a preheated metal conductor; S2. Polyethylene granules and dicumyl peroxide are added to a screw extruder and melted at 190~200℃. The melt is then extruded and coated onto a preheated metal conductor to obtain a polyethylene-coated metal conductor. Subsequently, the polyethylene-coated metal conductor is crosslinked under nitrogen at 200~210℃ for 10~30 min to obtain a metal conductor with an insulating layer. The amount of dicumyl peroxide added accounts for 1~3% of the mass of the polyethylene granules, and the thickness of the insulating layer is 5~8 mm. S3. The components of the sheath layer (3) are added into the internal mixer according to the weight parts, and the mixture is mixed at 130~140°C to obtain the sheath layer material. The sheath layer material is extruded onto the metal conductor with the insulation layer using an extruder to obtain the metal conductor with the sheath layer. Then, it is cooled and shaped to obtain the photovoltaic cable. The thickness of the sheath layer is 1.5~4mm.

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