Electrical insulation material for photovoltaic switchgear and method for producing the same

Abstract

The application belongs to the technical field of photovoltaic power distribution cabinet, and particularly relates to an electrical insulation material for a photovoltaic power distribution cabinet and a preparation method thereof, which comprises the following components in parts by weight: 40-60 parts of epoxy resin, 20-30 parts of silicone rubber, 10-15 parts of glass fiber, 5-10 parts of nano-aluminum oxide, 3-8 parts of flame retardant, 2-5 parts of toughening agent, 1-3 parts of antioxidant, and 1-3 parts of mica powder. Through the synergistic effect of the components, a "multi-scale composite structure" is formed in microcosm: the nano-aluminum oxide particles are uniformly dispersed to enhance the interfacial bonding force, the glass fiber forms a three-dimensional network to provide mechanical support, the epoxy resin and the silicone rubber form an interpenetrating network, and the toughening agent forms an elastic micro area. In addition, the flame retardants, aluminum hydroxide, magnesium hydroxide and microencapsulated flame retardant, further improve the flame retardant performance, thermal stability and electrical insulation performance of the insulation material, so that the insulation material can remain stable at-40 DEG C to 150 DEG C.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic power distribution cabinets, in particular to an electrical insulation material for photovoltaic power distribution cabinets and a preparation method thereof. BACKGROUND

[0002] In the operation process of photovoltaic power stations, photovoltaic power distribution cabinets play a crucial role in distributing, controlling and protecting the electrical energy generated by photovoltaic systems. However, the environment of photovoltaic power stations is complex and diverse, with large diurnal temperature differences in some areas, such as desert areas. The temperature of photovoltaic power distribution cabinets can reach above 50℃ under the high-temperature sun exposure during the day, and drop to below -10℃ at night. This frequent and large temperature change can cause thermal expansion and contraction of the insulation material inside the distribution cabinet. After long-term temperature cycling, the internal structure of the insulation material is easily damaged, causing cracks and other problems, which can lead to a decrease in insulation performance, seriously affecting the normal operation of photovoltaic power distribution cabinets, and even causing safety accidents.

[0003] In addition, during the operation of photovoltaic power distribution cabinets, the internal electrical components generate heat, causing the temperature inside the cabinet to rise. When the equipment stops running or the load changes, the temperature will decrease. This temperature fluctuation caused by operation can also affect the insulation material. Some existing insulation materials are difficult to maintain good structural stability and electrical insulation performance under long-term temperature fluctuations, limiting the reliable operation of photovoltaic power distribution cabinets in complex temperature environments. Chinese patent CN202211177889.1 provides a high-temperature-resistant cable insulation material and a preparation method thereof, which includes the following components A and component B by weight fraction: component A: low-density polyethylene 60-90 parts, ethylene-vinyl acetate copolymer 10-20 parts, benzene-silicon rubber 10-20 parts, carbon nanotubes 2-8 parts, potassium titanate whiskers 3-10 parts, silica microspheres 5-10 parts, compatibilizer 1-2 parts, flame retardant 140-160 parts, antioxidant 1.5-2.5 parts, component B: low-density polyethylene 20-30 parts, vulcanizing agent 0.2-0.4 parts. However, this insulation material cannot adapt to large temperature changes and maintain stable performance.

[0004] Therefore, it is of great practical significance to develop a photovoltaic power distribution cabinet electrical insulation material that can adapt to large temperature changes and maintain stable performance under different temperature conditions, and a preparation method thereof. SUMMARY

[0005] The present application provides an electrical insulation material for photovoltaic power distribution cabinet and a preparation method thereof, which has excellent temperature change resistance, can maintain stable structure and good electrical insulation performance under frequent and large temperature changes, solves the problem of long-term stable operation of the insulation material under extreme temperature difference conditions, and is suitable for long-term stable operation of the photovoltaic power distribution cabinet under extreme temperature difference conditions.

[0006] To solve the above technical problems, one technical scheme of the present application is an electrical insulation material for photovoltaic power distribution cabinet, which comprises the following components in parts by weight: epoxy resin 40-60 parts, silicone rubber 20-30 parts, glass fiber 10-15 parts, nano-alumina 5-10 parts, flame retardant 3-8 parts, toughening agent 2-5 parts, antioxidant 1-3 parts, and mica powder 1-3 parts.

[0007] Further, the antioxidant is a hindered phenolic antioxidant, and the toughening agent is a polyurethane elastomer.

[0008] Further, the particle size of the nano-alumina is 20-50 nm, and the length of the glass fiber is 1-3 um.

[0009] Further, the flame retardant comprises aluminum hydroxide, magnesium hydroxide, and microencapsulated flame retardant, and the mass ratio of aluminum hydroxide, magnesium hydroxide, and microencapsulated flame retardant is 3-4:3-4:5-6.

[0010] Epoxy resin has excellent mechanical strength and electrical insulation performance, but it is brittle and prone to cracking at low temperatures. Silicone rubber has good flexibility and high and low temperature resistance and can maintain elasticity at extreme temperatures. Therefore, the present application uses epoxy resin and silicone rubber as the matrix, forms an interpenetrating network structure by blending epoxy resin and silicone rubber, and forms a "rigid and flexible" composite system at the micro level. Epoxy resin provides rigid support, while silicone rubber fills in the molecular chains of epoxy resin and plays a buffering role. This structure can resist thermal expansion at high temperatures and relieve shrinkage stress at low temperatures, thereby avoiding material cracking.

[0011] Nano-alumina has high thermal conductivity, high hardness, and good thermal stability. Nano-alumina particles are uniformly dispersed in the matrix material, forming a "nano-reinforcement effect", which can effectively inhibit the expansion of internal cracks in the material and improve the thermal conductivity of the material, making the heat distribution more uniform and reducing local thermal stress. In addition, nano-alumina particles can also form a strong interfacial bond with the matrix material, enhancing the overall mechanical properties of the material.

[0012] Glass fibers have high strength and heat resistance, forming a three-dimensional network structure in the material, playing a "skeleton" role. At high temperatures, glass fibers can inhibit the thermal expansion of the matrix material; at low temperatures, glass fibers can resist shrinkage stress and prevent material cracking. At the same time, the interfacial bonding force between glass fibers and the matrix material is strong, which can effectively transfer stress and avoid stress concentration.

[0013] Toughening agents have high elasticity and flexibility, forming elastic microzones in the material, which can absorb energy when the material is subjected to thermal expansion and cold contraction stress, preventing the generation and propagation of cracks. This "elastic microzone" can maintain flexibility at low temperatures to avoid material brittleness, and stability at high temperatures to prevent material softening. Antioxidants can inhibit the oxidative degradation of materials at high temperatures, and aluminum hydroxide or magnesium hydroxide in inorganic fillers can improve the flame retardance of materials, while decomposing and absorbing heat at high temperatures to reduce material temperature. Antioxidants prevent material molecular chains from breaking at high temperatures by capturing free radicals. Flame retardants significantly improve the flame retardance, thermal stability, and electrical insulation performance of insulating materials through mechanisms such as heat absorption, water vapor generation, and protective layer formation. These performance improvements enable the material to operate stably for a long time in complex environments, meeting the needs of high-performance applications such as photovoltaic power distribution cabinets. In the present invention, hindered phenolic antioxidants protect the stability of materials at high temperatures by inhibiting oxidation reactions, extending the service life, and polyurethane elastomers improve the flexibility and impact resistance of materials to prevent cracking at low temperatures or under stress, further improving material performance. This enables the material to maintain stable electrical insulation performance and mechanical properties in extreme temperature environments, meeting the complex working condition requirements of photovoltaic power distribution cabinets.

[0014] Mica powder has excellent electrical insulation performance, which can significantly improve the dielectric strength and resistivity of insulating materials, reduce the dielectric loss of materials, and enhance the high temperature resistance of insulating materials, allowing them to maintain good insulation performance and mechanical properties at high temperatures. In addition, mica powder can also play a barrier role in insulating materials, preventing gas and liquid penetration, and improving the corrosion resistance and sealing performance of materials.

[0015] Aluminum hydroxide and magnesium hydroxide as efficient flame retardant, can be decomposed to generate water vapor at high temperature, the generation of water vapor can absorb a large amount of heat, reduce the material surface temperature, at the same time dilute the combustible gas concentration, in addition, the residue (aluminum oxide and magnesium oxide) after decomposition will form a dense protective layer on the material surface, further isolate the transmission of heat and oxygen, thereby significantly improve the flame retardant performance of the material. However, the consumption of aluminum hydroxide and magnesium hydroxide is an irreversible process, once consumed, the flame retardant performance of the material will decrease, and too much aluminum hydroxide and magnesium hydroxide flame retardant is easy to agglomerate, leading to uneven dispersion, poor compatibility with organic matrix material, thereby reducing the mechanical properties and electrical insulation properties of the material, low flame retardant efficiency, the material is brittle and easy to crack under stress. Therefore, the present application encapsulates aluminum hydroxide and magnesium hydroxide in microcapsules, when the material is subjected to high temperature, the microcapsules break to release the flame retardant, thereby restoring the flame retardant performance of the material. The present application uses aluminum hydroxide and magnesium hydroxide as core material, polylactic acid, polycaprolactone, polycarbonate and nanosilica as shell material, and prepares microencapsulated flame retardant by interfacial polymerization.

[0016] The preparation method of the microencapsulated flame retardant is as follows:

[0017] (1) aluminum hydroxide, magnesium hydroxide and dispersant are added to deionized water, stirred for 10-15 min to form a stable suspension;

[0018] (2) polylactic acid, polycaprolactone and polycarbonate are dissolved in dichloromethane to form an oil phase, and nanosilica is dispersed in the oil phase;

[0019] (3) the suspension is mixed with the emulsifier, stirred uniformly, and the oil phase is slowly added under high speed stirring for 5-10 min to form an oil-in-water (O / W) emulsion, then the stabilizer is added to the emulsion, and the stirring is continued, and the reaction is carried out at room temperature for 4-6 h, so that the shell material forms a dense microcapsule shell on the surface of aluminum hydroxide and magnesium hydroxide;

[0020] (4) the reaction suspension is filtered, the microcapsules are collected, washed with deionized water for 3-5 times, vacuum dried at 40-50℃ for 4-6 h, and then a layer of polytetrafluoroethylene is coated on the surface of the microcapsules to obtain dry microencapsulated flame retardant.

[0021] Further, the mass ratio of core material aluminum hydroxide and magnesium hydroxide in step (1) is 3-4:3-4, the dispersant is polyvinylpyrrolidone, the addition amount of dispersant is 2%-4% of the mass of core material, and the mass of deionized water is 3-6 times of the mass of core material.

[0022] Furthermore, in step (2), the mass ratio of the shell material polylactic acid, polycaprolactone, polycarbonate and nano silica is 14:3:3:2, and the total mass of the shell material is 45% to 55% of the total mass of the core material in step (1), and the mass of dichloromethane is 5 to 10 times the total mass of the shell material.

[0023] Furthermore, in step (3), the emulsifier is sodium dodecyl sulfate, and the amount added is 2% to 4% of the mass of the core material; the stabilizer is polyvinyl alcohol, and the amount added is 2% to 3% of the mass of polylactic acid.

[0024] Furthermore, the stirring speed in step (1) is 1000-1500 rpm, and the stirring speed in step (3) is 1500-2000 rpm.

[0025] Further, the specific operation method for coating the surface of the microcapsules with a layer of polytetrafluoroethylene in step (4) is as follows: disperse polytetrafluoroethylene powder in deionized water to a concentration of 1-2 wt%, add sodium dodecyl sulfate dispersant of 0.05%-0.1% by weight of polytetrafluoroethylene to form a stable suspension, immerse the microcapsules in the suspension, stir at 50-100 rpm for 5-10 min, take out the microcapsules, and vacuum dry at 40-50℃ for 2-4 h to cure the polytetrafluoroethylene coating.

[0026] The shell material is a blend of polylactic acid, polycaprolactone, and polycarbonate. Polylactic acid has a melting point of approximately 150–160°C, polycarbonate has a glass transition temperature (Tg) of approximately 150°C, and the addition of polycaprolactone improves the low-temperature toughness of the shell. The synergistic effect of these three materials ensures the stability of the shell at high temperatures. Nano-silica (SiO2) is added as a heat-resistant filler to further improve the thermal stability and mechanical strength of the shell. In addition, the shell thickness is adjusted to approximately 200–300 nm by controlling the mass ratio of the core material to the shell material and the emulsification time. Finally, a polytetrafluoroethylene (PTFE) coating is applied to the surface of the microcapsules to further enhance the heat resistance and hydrophobicity of the shell, enabling the microcapsules to rupture stably and release the flame retardant in the range of 150–180°C. This matches the decomposition temperature of aluminum hydroxide and magnesium hydroxide, thereby achieving effective release of the flame retardant.

[0027] To solve the above-mentioned technical problems, another technical solution provided by the present invention is: a method for preparing electrical insulation material for photovoltaic distribution cabinets, the specific steps of which are as follows:

[0028] S1: Preparation of composite polymer masterbatch: Add mica powder, nano alumina and toughening agent to a high-speed mixer in the mixing direction, mix for 10-15 min and then extrude and granulate using a twin-screw extruder;

[0029] S2: mixing: open the cooling water, adjust the roller speed of the front and rear rollers of the double roller mill to 1:1.2, pass the master batch, epoxy resin and silicone rubber prepared in step S1 through the roller according to the formula, plasticize for 2-5 min, adjust the roller gap to 2-3 mm, after the master batch is wrapped around the roller, add glass fiber and antioxidant in turn, control the roller temperature to 100-120 DEG C, mix for 10-15 min to make it uniformly dispersed, pack, thin pass 5 times, adjust the roller gap to 2 mm thickness, and get the mixing rubber sheet;

[0030] S3: vulcanization forming: after the mixing rubber sheet prepared in step S2 is placed at room temperature for 18-24 h, it is placed in a 15-20 MPa flat plate vulcanizing machine for high temperature vulcanization forming, and the insulating material is obtained.

[0031] Further, the high temperature vulcanization in step S3 is divided into primary vulcanization and secondary vulcanization, the primary vulcanization reaction temperature is 120-140 DEG C, and the reaction time is 30-40 min; the secondary vulcanization reaction temperature is 200-220 DEG C, and the reaction time is 50-60 min.

[0032] The beneficial effects of the present application are:

[0033] The present application provides an electrical insulating material for photovoltaic power distribution cabinet, through the synergistic effect of each component, a "multi-scale composite structure" is formed at the micro level: nano aluminum oxide particles are uniformly dispersed to enhance the interfacial bonding strength, glass fibers form a three-dimensional network to provide mechanical support, and epoxy resin and silicone rubber form a interpenetrating network toughening agent to form an elastic micro area. This multi-scale composite structure can effectively disperse stress at extreme temperatures and avoid local stress concentration, thereby maintaining the overall stability of the material. In addition, the flame retardants aluminum hydroxide, magnesium hydroxide and microencapsulated flame retardant further improve the flame retardant performance, thermal stability and electrical insulation performance of the insulating material. Therefore, the present application improves the comprehensive performance of the material from the aspects of chemical stability and mechanical properties, so that it can remain stable in the temperature range of -40 DEG C to 150 DEG C. At the same time, the preparation method of the present application is reasonable and operable, and is suitable for industrial production, and can prepare high-performance electrical insulating materials that meet the use requirements of photovoltaic power distribution cabinets under complex working conditions. DETAILED DESCRIPTION

[0034] The present application will be further described below in conjunction with examples, but it is not limited by the examples. The experimental methods in the following examples are conventional methods, unless otherwise specified.

[0035] Example 1

[0036] An electrical insulation material of a photovoltaic power distribution cabinet, comprising the following components by weight parts: epoxy resin 40 parts, silicone rubber 20 parts, glass fiber 10 parts, nano-aluminum oxide 5 parts, flame retardant 3 parts, polyurethane elastomer 2 parts, hindered phenolic antioxidant 1 part, mica powder 1 part.

[0037] Further, the flame retardant comprises aluminum hydroxide, magnesium hydroxide, microencapsulated flame retardant, and the mass ratio of aluminum hydroxide, magnesium hydroxide, and microencapsulated flame retardant is 3:3:5.

[0038] The present application adopts aluminum hydroxide and magnesium hydroxide as core materials, polylactic acid, polycarbonate and nano-silicon dioxide as shell materials, and prepares microencapsulated flame retardant by interfacial polymerization, and the specific preparation method is as follows:

[0039] (1) Add aluminum hydroxide and magnesium hydroxide with a mass ratio of 1:1 and polyvinylpyrrolidone with a mass of 2% of the total mass of aluminum hydroxide and magnesium hydroxide to deionized water, wherein the mass of deionized water is 3 times the total mass of aluminum hydroxide and magnesium hydroxide, 1000 rpm stirring for 10 min to form a stable suspension;

[0040] (2) Dissolve polylactic acid, polycaprolactone and polycarbonate in dichloromethane to form an oil phase, and then disperse nano-silicon dioxide in the oil phase, wherein the mass ratio of shell materials polylactic acid, polycaprolactone, polycarbonate and nano-silicon dioxide is 14:3:3:2, and the total mass of shell materials is 45% of the total mass of core materials in step (1), and the mass of dichloromethane is 5 times the total mass of shell materials;

[0041] (3) Mix the suspension with sodium dodecyl sulfate with a mass of 2% of the mass of aluminum hydroxide and magnesium hydroxide, stir uniformly, slowly add the oil phase, emulsify for 5 min under high-speed stirring at 1500 rpm to form an oil-in-water (O / W) emulsion, then add polyvinyl alcohol to the emulsion, continue to stir, and react for 4 h at room temperature to form a dense microcapsule shell on the surface of aluminum hydroxide and magnesium hydroxide;

[0042] (4) Filter the reacted suspension, collect the microcapsules, wash with deionized water for 3-5 times, and vacuum dry at 40-50℃ for 4-6h to obtain dry microcapsules;

[0043] (5) Disperse polytetrafluoroethylene powder in deionized water to a concentration of 1 wt%, add 0.05% of sodium dodecyl sulfate dispersant based on the mass of polytetrafluoroethylene, form a stable suspension, immerse the microcapsules obtained in step (4) in the suspension, stir at 50 rpm for 5 min, take out the microcapsules, and vacuum dry at 40℃ for 2h to obtain dry microcapsules coated with a layer of polytetrafluoroethylene.

[0044] A preparation method of an electrical insulation material of a photovoltaic power distribution cabinet, the specific steps are as follows:

[0045] S1: preparing a composite polymer master batch: adding mica powder, nano-aluminum oxide and toughening agent into a high-speed mixer in a mixing direction, mixing for 10-15 min, and then extruding and granulating by using a double-screw extruder;

[0046] S2: mixing: opening the cooling water, adjusting the roller speed of the front and rear rollers of a double-roller mixing mill to 1:1.2, passing the master batch prepared in step S1, epoxy resin and silicone rubber through the rollers for plasticizing for 2-5 min according to the formula, adjusting the roller distance to 2-3 mm, adding glass fiber and antioxidant in sequence after the master batch is wrapped around the rollers, controlling the roller temperature to be 100-120 DEG C, mixing for 10-15 min to make them uniformly dispersed, packing, and passing through the rollers for 5 times, adjusting the roller distance to obtain a mixing rubber sheet with a thickness of 2 mm;

[0047] S3: vulcanization forming: after the mixing rubber sheet prepared in step S2 is placed at room temperature for 18-24 h, it is placed in a 15-20 MPa flat plate vulcanizing machine for high-temperature vulcanization, the first vulcanization reaction temperature is 120-140 DEG C, the reaction time is 30-40 min, the second vulcanization reaction temperature is 200-220 DEG C, the reaction time is 50-60 min, and the insulation material is obtained.

[0048] Example 2

[0049] An electrical insulation material of a photovoltaic power distribution cabinet, comprising the following components by weight: epoxy resin 60 parts, silicone rubber 30 parts, glass fiber 15 parts, nano-aluminum oxide 10 parts, flame retardant 8 parts, polyurethane elastomer 5 parts, hindered phenolic antioxidant 3 parts, mica powder 3 parts.

[0050] Further, the flame retardant comprises aluminum hydroxide, magnesium hydroxide, and microencapsulated flame retardant, and the mass ratio of aluminum hydroxide, magnesium hydroxide, and microencapsulated flame retardant is 4:4:5.

[0051] The application adopts aluminum hydroxide and magnesium hydroxide as core materials, polylactic acid, polycarbonate and nano-silicon dioxide as shell materials, and prepares a microencapsulated flame retardant by an interfacial polymerization method, and the specific preparation method is as follows:

[0052] (1) adding aluminum hydroxide and magnesium hydroxide with a mass ratio of 3:4 and polyvinylpyrrolidone with a mass of 4% of the total mass of aluminum hydroxide and magnesium hydroxide into deionized water, wherein the mass of the deionized water is 6 times the total mass of aluminum hydroxide and magnesium hydroxide, stirring at 1500 rpm for 15 min to form a stable suspension;

[0053] (2) Dissolve polylactic acid, polycaprolactone and polycarbonate in dichloromethane to form an oil phase, and then disperse nano-silicon dioxide in the oil phase, wherein the mass ratio of the shell materials polylactic acid, polycaprolactone, polycarbonate and nano-silicon dioxide is 14:3:3:2, and the total mass of the shell materials is 55% of the total mass of the core material in step (1), and the mass of dichloromethane is 10 times the total mass of the shell materials;

[0054] (3) Mix the suspension with 4% sodium dodecyl sulfate by mass of aluminum hydroxide and magnesium hydroxide, stir uniformly, slowly add the oil phase, emulsify under high-speed stirring at 2000 rpm for 10 min to form an oil-in-water (O / W) emulsion, then add polyvinyl alcohol to the emulsion, continue to stir, and react at room temperature for 6 h to form a dense microcapsule shell on the surface of the aluminum hydroxide and magnesium hydroxide;

[0055] (4) Filter the reacted suspension, collect the microcapsules, wash with deionized water 5 times, and vacuum dry at 50°C for 6 h to obtain dried microcapsules;

[0056] (5) Disperse polytetrafluoroethylene powder in deionized water to a concentration of 2 wt%, add 0.1% sodium dodecyl sulfate dispersant by mass of polytetrafluoroethylene, form a stable suspension, immerse the microcapsules obtained in step (4) in the suspension, stir at 100 rpm for 10 min, take out the microcapsules, and vacuum dry at 50°C for 4 h to obtain dried microcapsulated flame retardant coated with a layer of polytetrafluoroethylene.

[0057] A preparation method of an electrical insulation material for a photovoltaic power distribution cabinet, the specific steps are as follows:

[0058] S1: Prepare a composite polymer master batch: add mica powder, nano-alumina and toughening agent to a high-speed mixer according to the formula, mix for 15 min, and then extrude and granulate with a twin-screw extruder;

[0059] S2: Mixing: open the cooling water, adjust the roller speed of the front and rear rollers of the double roller mixing mill to 1:1.2, pass the master batch prepared in step S1, epoxy resin and silicone rubber through the roller plasticizing machine according to the formula, adjust the roller gap to 3 mm, and after the master batch is wrapped around the roller, add glass fiber and antioxidant in sequence, control the roller temperature to 120°C, mix for 15 min to make them uniformly dispersed, pack, and pass through the mill 5 times, adjust the roller gap to 2 mm thickness, and cut the mixed rubber sheet to obtain the mixed rubber sheet;

[0060] S3: Vulcanization molding: after the mixed rubber sheet prepared in step S2 is placed at room temperature for 24 h, it is placed in a 20 MPa flat plate vulcanizer for high temperature vulcanization, the first vulcanization reaction temperature is 140°C, and the reaction time is 40 min; the second vulcanization reaction temperature is 220°C, and the reaction time is 60 min, and the insulation material is obtained by vulcanization molding.

[0061] Example 3

[0062] An electrical insulation material for a photovoltaic power distribution cabinet comprises the following components by weight parts: epoxy resin 50 parts, silicone rubber 25 parts, glass fiber 12 parts, nano-aluminum oxide 8 parts, flame retardant 5 parts, polyurethane elastomer 3 parts, hindered phenolic antioxidant 2 parts, mica powder 2 parts.

[0063] Further, the flame retardant comprises aluminum hydroxide, magnesium hydroxide, microencapsulated flame retardant, and the mass ratio of aluminum hydroxide, magnesium hydroxide, and microencapsulated flame retardant is 1:1:2.

[0064] The present application adopts aluminum hydroxide and magnesium hydroxide as core materials, polylactic acid, polycarbonate, and nano-silicon dioxide as shell materials, and prepares a microencapsulated flame retardant by an interfacial polymerization method, and the specific preparation method is as follows:

[0065] (1) Add aluminum hydroxide and magnesium hydroxide with a mass ratio of 4:3 and polyvinylpyrrolidone with a mass of 3% of the total mass of aluminum hydroxide and magnesium hydroxide to deionized water, wherein the mass of deionized water is 5 times the total mass of aluminum hydroxide and magnesium hydroxide, and stir at 1250 rpm for 12 min to form a stable suspension;

[0066] (2) Dissolve polylactic acid, polycaprolactone, and polycarbonate in dichloromethane to form an oil phase, and then disperse nano-silicon dioxide in the oil phase, wherein the mass ratio of the shell materials polylactic acid, polycaprolactone, polycarbonate, and nano-silicon dioxide is 14:3:3:2, and the total mass of the shell materials is 50% of the total mass of the core materials in step (1), and the mass of dichloromethane is 8 times the total mass of the shell materials;

[0067] (3) Mix the suspension with sodium dodecyl sulfate with a mass of 3% of the mass of aluminum hydroxide and magnesium hydroxide, stir uniformly, slowly add the oil phase, emulsify at 1750 rpm for 7 min to form an oil-in-water (O / W) emulsion, then add polyvinyl alcohol to the emulsion, continue to stir, and react at room temperature for 5 h to form a dense microcapsule shell on the surface of aluminum hydroxide and magnesium hydroxide;

[0068] (4) Filter the reacted suspension, collect the microcapsules, wash them with deionized water 4 times, and vacuum dry at 45°C for 5 h to obtain dried microcapsules;

[0069] (5) Disperse the polytetrafluoroethylene powder in deionized water to obtain a suspension with a concentration of 1.5 wt%, add 0.07% of the mass of the polytetrafluoroethylene of sodium dodecyl sulfate dispersant to form a stable suspension, immerse the microcapsules obtained in step (4) in the suspension, stir at 75 rpm for 7 min, take out the microcapsules, and vacuum dry at 45℃ for 3 h to obtain dried microencapsulated flame retardant coated with a layer of polytetrafluoroethylene.

[0070] A preparation method of an electrical insulation material of a photovoltaic power distribution cabinet, the specific steps are as follows:

[0071] S1: Preparation of composite polymer master batch: add mica powder, nano-aluminum oxide and toughening agent into a high-speed mixer according to the formula, mix for 12 min, and then extrude and granulate by a twin-screw extruder;

[0072] S2: Mixing: open the cooling water, adjust the roller speed of the front and rear rollers of the double roller mill to 1:1.2, pass the master batch prepared in step S1, epoxy resin and silicone rubber through the roller plasticizing machine according to the formula, adjust the roller gap to 2.5 mm, and after the master batch is wrapped around the roller, add glass fiber and antioxidant in sequence, control the roller temperature to be 110℃, mix for 12 min to make them uniformly dispersed, pack, and pass through the thin passageway for 5 times, adjust the roller gap to 2 mm thickness to obtain the mixing rubber sheet;

[0073] S3: Vulcanization molding: after the mixing rubber sheet prepared in step S2 is placed at room temperature for 21 h, it is placed in an 18 MPa flat plate vulcanizer for high temperature vulcanization, the first vulcanization reaction temperature is 130℃, and the reaction time is 35 min; the second vulcanization reaction temperature is 210℃, and the reaction time is 55 min, and the insulation material is obtained by vulcanization molding.

[0074] Comparative Example 1: The comparative example 1 is basically the same as example 3, except that there is no microencapsulated flame retardant in the flame retardant.

[0075] Comparative Example 2: The comparative example 2 is basically the same as example 3, except that the preparation step of the microencapsulated flame retardant does not have step (5).

[0076] Test experiment:

[0077] Five insulation materials of examples 1-3 and comparative examples 1-2 are tested as test samples, and the test results are shown in Tables 1 and 2.

[0078] 1. Performance test results

[0079] Table 1 Performance test results

[0080] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Heat Deflection Temperature (°C) 150 145 160 80 90 Limiting Oxygen Index (%) 32 30 31 26 28 Vertical Burning Test (Rating) V-0 V-1 V-0 Fail Fail Fail Fail V-2

[0081] 2. Temperature cycle test

[0082] Refer to international standard IEC 60068-2-14 (Environmental testing - Part 2-14: Test N - Temperature change) or GB / T2423.22 (Environmental testing for electrical and electronic products - Test method for temperature change).

[0083] Test equipment: High and low temperature alternating test chamber, programmable temperature range (-70℃ to +200℃), adjustable heating and cooling rate.

[0084] Test steps:

[0085] (1) Sample preparation

[0086] Standard test cube-shaped samples were prepared from the products of Examples 1-3 and Comparative Examples 1-2. The dimensions of the samples conformed to the relevant test standards (such as ISO 527 and ASTM D149). At least 5 sets of each sample were prepared to ensure the reliability of the data.

[0087] (2) Preprocessing

[0088] The samples were placed in a standard laboratory environment (23℃±2℃, 50%±5% RH) for 24 hours to eliminate processing stress.

[0089] (3) Temperature cycle program setting

[0090] High temperature setting: 150℃; Low temperature setting: -40℃;

[0091] Number of cycles: 50-100 (adjust according to actual working conditions);

[0092] Single loop process:

[0093] Heating phase: from room temperature to 150℃, heating rate ≤ 5℃ / min;

[0094] High temperature maintenance: Maintain at 150℃ for 2 hours;

[0095] Cooling phase: from 150℃ to -40℃, cooling rate ≤5℃ / min;

[0096] Low temperature holding: Keep at -40℃ for 2 hours;

[0097] Warming up phase: from -40℃ to room temperature, with a heating rate ≤5℃ / min.

[0098] (4) Test execution

[0099] Place the samples in a high and low temperature chamber, ensuring sufficient space between them (to avoid interference from heat conduction); start the temperature cycling program and record the temperature and humidity inside the chamber and the surface temperature of the samples throughout the process; after every 10 cycles, remove a portion of the samples for intermediate performance testing.

[0100] Table 2 Temperature cycling test results

[0101]

[0102] As shown in Table 1 and Table 2, the limiting oxygen index of Examples 1-3: 30%-32%, significantly better than the comparative examples (26%-28%); vertical burning test: Examples 1 and 3 reach V-0 level, Example 2 is V-1 level, while Comparative Example 1 fails, and Comparative Example 2 is only V-2 level. Therefore, the examples containing microencapsulated flame retardants can significantly improve the flame retardant efficiency, and the polytetrafluoroethylene coating can further optimize the performance.

[0103] The heat distortion temperature (145-160℃) of Examples 1-3 is much higher than that of Comparative Examples 1-2 (80-90℃), and the temperature cycling resistance (50 times), the tensile strength retention rate of Examples is ≥90%, and the dielectric strength retention rate is ≥85%; while the performance of the comparative examples is greatly reduced (tensile strength retention rate ≤76%, dielectric strength retention rate ≤55%). Therefore, the microencapsulated flame retardant and PTFE coating synergistically resist the performance degradation caused by extreme temperature difference.

[0104] The present application significantly improves the material flame retardancy, temperature stability and reliability in extreme environments through the design of microencapsulated flame retardant and PTFE coating.

[0105] The preferred embodiments of the present application disclosed above are only used to help explain the present application. The preferred embodiments do not describe all the details, nor limit the application to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of the present application. The present application selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application. The present application is limited only by the claims and their full scope and equivalents.

Claims

1. An electrical insulation material for a photovoltaic distribution cabinet, characterized in that, The product comprises the following components in parts by weight: 40-60 parts epoxy resin, 20-30 parts silicone rubber, 10-15 parts glass fiber, 5-10 parts nano alumina, 3-8 parts flame retardant, 2-5 parts toughening agent, 1-3 parts antioxidant, and 1-3 parts mica powder. Flame retardants include aluminum hydroxide, magnesium hydroxide, and microencapsulated flame retardants, with a mass ratio of aluminum hydroxide, magnesium hydroxide, and microencapsulated flame retardants of 3-4:3-4:5-6. The microencapsulated flame retardant uses aluminum hydroxide and magnesium hydroxide as core materials, and polylactic acid, polycaprolactone, polycarbonate, and nano-silica as shell materials. It is prepared by interfacial polymerization, and the specific steps are as follows: (1) Add aluminum hydroxide, magnesium hydroxide and dispersant to deionized water and stir for 10-15 minutes to form a stable suspension; (2) Polylactic acid, polycaprolactone and polycarbonate are dissolved in dichloromethane to form an oil phase, and then nano-silica is dispersed in the oil phase; (3) Mix the suspension with the emulsifier, stir evenly, slowly add the oil phase, emulsify for 5-10 minutes under high speed stirring to form an oil-in-water (O / W) emulsion, then add the stabilizer to the emulsion, continue stirring, and react at room temperature for 4-6 hours to form a dense microcapsule shell on the surface of aluminum hydroxide and magnesium hydroxide. (4) Filter the suspension after the reaction, collect the microcapsules, wash them with deionized water 3 to 5 times, vacuum dry them at 40 to 50°C for 4 to 6 hours, and then coat the surface of the microcapsules with a layer of polytetrafluoroethylene to obtain the dried microencapsulated flame retardant.

2. The electrical insulation material of a photovoltaic distribution cabinet according to claim 1, characterized in that, The antioxidant is a hindered phenolic antioxidant, the toughening agent is a polyurethane elastomer, the particle size of the nano-alumina is 20-50 nm, and the length of the glass fiber is 1-3 μm.

3. The electrical insulation material of a photovoltaic distribution cabinet according to claim 1, characterized in that, In step (1), the mass ratio of the core materials aluminum hydroxide and magnesium hydroxide is 3-4:3-4, the dispersant is polyvinylpyrrolidone, the amount of dispersant added is 2%-4% of the mass of the core materials, and the mass of deionized water is 3-6 times the mass of the core materials.

4. The electrical insulation material of a photovoltaic distribution cabinet according to claim 1, characterized in that, In step (2), the mass ratio of the shell material polylactic acid, polycaprolactone, polycarbonate and nano silica is 14:3:3:2, and the total mass of the shell material is 45% to 55% of the total mass of the core material in step (1), and the mass of dichloromethane is 5 to 10 times the total mass of the shell material.

5. The electrical insulation material of a photovoltaic distribution cabinet according to claim 1, characterized in that, In step (3), the emulsifier is sodium dodecyl sulfate, and the amount added is 2% to 4% of the mass of the core material. The stabilizer is polyvinyl alcohol, and the amount added is 2% to 3% of the mass of polylactic acid.

6. The electrical insulation material of a photovoltaic distribution cabinet according to claim 1, characterized in that, The stirring speed in step (1) is 1000-1500 rpm, and the stirring speed in step (3) is 1500-2000 rpm.

7. The electrical insulation material of a photovoltaic distribution cabinet according to claim 1, characterized in that, The specific operation method for coating the surface of the microcapsules with a layer of polytetrafluoroethylene in step (4) is as follows: Disperse polytetrafluoroethylene powder in deionized water to a concentration of 1-2 wt%, add sodium dodecyl sulfate dispersant of 0.05%-0.1% by weight of polytetrafluoroethylene to form a stable suspension, immerse the microcapsules in the suspension, stir at 50-100 rpm for 5-10 min, take out the microcapsules, and vacuum dry at 40-50℃ for 2-4 h to cure the polytetrafluoroethylene coating.

8. The method for preparing the electrical insulation material of the photovoltaic distribution cabinet as described in any one of claims 1 to 7, characterized in that, The preparation method includes the following steps: S1: Preparation of composite polymer masterbatch: Add mica powder, nano alumina and toughening agent to a high-speed mixer in the mixing direction, mix for 10-15 minutes, and then extrude and granulate using a twin-screw extruder; S2: Mixing: Turn on the cooling water and adjust the speed of the front and rear rollers of the two-roll mill to 1:1.

2. According to the formula, the masterbatch, epoxy resin and silicone rubber prepared in step S1 are plasticized through the rollers for 2 to 5 minutes. Adjust the roller gap to 2 to 3 mm. After the masterbatch wraps around the rollers, glass fiber and antioxidant are added in sequence. The roller temperature is controlled at 100 to 120°C. Mix for 10 to 15 minutes to make it evenly dispersed. Pack and thin pass 5 times each. Adjust the roller gap to cut the sheet to a thickness of 2 mm to obtain the mixed rubber sheet. S3: Vulcanization molding: After the compounded rubber sheet prepared in step S2 is left to stand at room temperature for 18-24 hours, it is placed in a 15-20MPa flat vulcanizing machine for high-temperature vulcanization molding to obtain the insulating material.

9. The preparation method according to claim 8, characterized in that, In step S3, high-temperature vulcanization is divided into primary vulcanization and secondary vulcanization. The primary vulcanization reaction temperature is 120-140℃ and the reaction time is 30-40 min. The secondary vulcanization reaction temperature is 200-220℃ and the reaction time is 50-60 min.

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