Preparation of insulation spraying material for cross arm side of power transmission tower and method therefor

Abstract

The present invention relates to the technical field of coatings, and specifically relates to the preparation of an insulation spraying material for a cross arm side of a power transmission tower and a method therefor. The preparation comprises adding a component A and a component B into a material pipe of a spraying gun at the cross arm side according to an appropriate proportion, connecting a 600 kPa or above air compressor with the spraying gun, and spraying a mixture onto the surface of an aluminum plate, which has been cleaned with absolute ethyl alcohol. The sprayed materials are cured at a normal temperature and repeatedly sprayed two to three times to increase the thickness of a coating, so as to form a polyurea resin coating. By using the component A, i.e. an isocyanate prepolymer, and the component B, i.e. an amine compound, the cross arm side part of a 110 kV tower is sprayed in a two-component spraying manner, thus preventing the short circuit faults caused by bird damage and other factors. The curing time of the insulating layer formed by means of the curing of polyurea is short, without forming dripping hanging. In addition, the appearance of a power device can be ignored. The polyurea material prepared by means of subjecting the part needing to be insulated from indiscriminate spraying has a relatively high heat conductivity and insulativity and good spraying effects.

Description

Preparation and method of insulation spray material for cross-arm side of transmission tower Technical Field

[0001] The present invention relates to the technical field of coatings, in particular to a preparation method of an insulating spray material for a cross-arm side of a transmission tower. Background Art

[0002] In areas with severe industrial pollution, the long-term deposition of atmospheric contaminants significantly increases the surface contamination density of RTV-coated insulators, significantly increasing the probability of contamination accidents. Because the RTV water angle is less than 110° and the rolling angle is relatively large, water droplets tend to condense on the RTV surface under conditions such as fog, rain, or condensation, making it difficult for them to roll off. When condensation is severe, the water droplets dissolve charged particles in the contaminants, forming a large conductive water film that is highly susceptible to surface flashing on the insulator. Furthermore, numerous recent surveys have shown that in the typical subtropical climate of southern China, characterized by strong radiation, high humidity, and heat, RTV coatings not only face severe surface contamination accumulation due to environmental pollution, but also face the risk of peeling, chalking, and even shedding due to UV aging. Long-term UV radiation damages the molecular chains of RTV silicone rubber, altering its chemical structure and causing the coating to lose its hydrophobicity. Consequently, the flashover voltage of the contaminant is significantly reduced.

[0003] Currently, RTV coatings are primarily used for insulators, but there's still a gap in the spray coating material for the crossarm side. Furthermore, RTV's long curing time makes it difficult to form a thick insulating protective layer on the surface. A highly insulating, fast-curing spray material is urgently needed to fill this gap in the industry. Using polyurea as an alternative, however, will significantly reduce its thermal conductivity compared to RTV. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for preparing an insulating spray material for the cross-arm side of a transmission tower, which solves the problems raised in the above background technology. To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for preparing an insulating spray material for the cross-arm side of a transmission tower comprises the following steps:

[0005] Step 1: Synthesis of isocyanate prepolymer component A: 75 mmol of 4,4-methylenebis(phenyl isocyanate) and 11.25 mmol of polyether polyol were added to a condensation reflux magnetic stirring apparatus and reacted at 80°C under a nitrogen atmosphere for 3 hours to form isocyanate prepolymer component A;

[0006] Step 2: Synthesis of Component B Amine Compounds: 7.6 mmol of 3,3-dichloro-4,4-diaminodiphenylmethane and 3.25 mmol of amino-terminated polyether were added to 15 ml of a silane coupling agent. Five fillers (1 part by mass equals 0.5 g) with kaolin:boron nitride ratios of 1:1, 1.2:1, 1.5:1, 1:1.5, and 1:1.2 were added, respectively. The mixture was stirred for 5 hours. The resulting five Component Bs with different filler ratios were named 1#, 2#, 3#, 4#, and 5#.

[0007] Step 3: Add components A and B in appropriate proportions to the material pipe of the crossarm spray gun. Connect the gun to an air compressor with a pressure of at least 600 kPa and spray the mixture onto the aluminum plate, which has been cleaned with anhydrous ethanol. After spraying, allow the material to cure at room temperature. Repeat the spraying process two to three times to increase the coating thickness and form a polyurea resin coating.

[0008] Preferably, the molecular weight of the polyether polyol in the component A in the step 1 is 4000 g / mol and the purity of the nitrogen used is 99.99%.

[0009] Preferably, the mixing ratio of the amine compound and the silane coupling agent in the component B in the step 2 is 5:1.

[0010] Preferably, the reaction temperature in step 1 is maintained at 80°C ± 5°C and the stirring rate is 300 rpm. In step 2, the five different kaolin and boron nitride filler mass ratios can be adjusted according to actual test results to achieve optimal mechanical properties and electrical insulation properties.

[0011] Preferably, the aluminum plate after spraying in step 3 needs to be cured at room temperature for 24 hours and then heat-cured at 120° C. for 2 hours to ensure that the weather resistance and electrical insulation performance of the coating meet the expected standards.

[0012] Preferably, the molecular weight of the polyether polyol in step 1 should be 4000 g / mol. The molecular weight of the isocyanate containing at least four hydroxy groups should be controlled at a ratio of 0.67:1 to ensure the reactivity of the prepolymer. The nitrogen used during the reaction should be 99.99% pure to ensure that the reaction environment is free of moisture or impurities to avoid affecting the reaction effect. The reaction temperature should be strictly controlled within the range of 80°C ± 5°C. Excessively high temperatures will cause the reaction to proceed too quickly and affect product quality; excessively low temperatures may lead to incomplete reaction.

[0013] Preferably, the stirring rate in step 1 is controlled at 300 rpm to ensure thorough mixing of the reactants and avoid localized overheating or underheating. The reaction time is controlled to 3 hours, within which component A will completely react to form an isocyanate prepolymer with high viscosity and appropriate reactivity. After the reaction, the product should be cooled and initially analyzed to ensure that its molecular structure meets the requirements. Infrared spectroscopy (FTIR) analysis can be used to monitor isocyanate group consumption and ensure the quality of the prepolymer.

[0014] Preferably, the purity of the amine compound 3,3-dichloro-4,4-diaminodiphenylmethane in step 2 reaches 99% or higher to ensure the completeness of the reaction and the stability of the final product. The filler selection: The mass ratio of kaolin to boron nitride should be adjusted based on different experimental test results. Mechanical and electrical performance tests are required to determine the optimal ratio. Stirring is performed under nitrogen to prevent the negative impact of moisture and oxygen in the air on the reaction. The stirring time should be 5 hours to ensure complete reaction and sufficient reaction between the filler and the amine compound. It is recommended to use a magnetic stirrer or high-shear mixer to ensure material uniformity. The type of silane coupling agent used is 3-aminopropyltriethoxysilane, and the mass of the coupling agent should be 5% of the total reactants.

[0015] Preferably, the mass ratio of component A to component B in step three should be controlled between 1:1.05 and 1:1.2 to ensure the proper curing speed and performance stability of the resin. This ratio should be fine-tuned based on environmental conditions (such as humidity and temperature). The pressure used during spraying should be greater than 600 kPa to ensure thorough mixing of components A and B in the spray gun. The nozzle diameter of the spray gun should be 2 mm. The spraying distance should be 150 mm ± 10 mm. Spraying should be uniform and continuous to avoid excessively thick or thin coatings in certain areas. The sprayed aluminum plate should be cured at room temperature for 24 hours to ensure surface dryness and curing. The temperature should not exceed 30°C during the curing process to prevent high temperatures from degrading the material. After 24 hours of room-temperature curing, the aluminum plate is placed in a 120°C oven for 2 hours to stabilize the molecular structure of the polyurea coating and enhance its anti-aging properties. The cured coating thickness should reach 200 μm to 300 μm to ensure good electrical insulation and mechanical strength.

[0016] A performance testing method for insulation spraying materials on the cross-arm side of a transmission tower, including the following testing methods:

[0017] S1: Electrical performance test:

[0018] Insulation resistance test: Use a high-voltage insulation resistance tester (test voltage is 5000V) to test the insulation resistance of the coating to ensure it is not less than 10^9 Ω·m;

[0019] Dielectric strength test: The dielectric strength of the coating is measured using the electrical breakdown test method (IEC 60243-1 standard) under standard test conditions and is required to be no less than 25kV / mm;

[0020] S2: Mechanical properties test: Tensile strength test: Use a tensile testing machine to test the tensile strength of the polyurea coating, which is required to be above 15 MPa;

[0021] Hardness test: Use Shore A hardness tester to test the coating surface hardness should reach 75~85 degrees;

[0022] S3: Weathering test: Place the coating sample in an accelerated aging test chamber (UV radiation, temperature and humidity cycling) for 300 hours. After the test, check the coating for cracks, peeling, or color changes.

[0023] Compared with the existing technology, it has the following beneficial effects:

[0024] The benefits of this application are:

[0025] The present application uses a two-component spraying method using an isocyanate prepolymer as component A and an amine compound as component B to spray the cross-arm side of the transmission tower, thereby preventing short-circuit failures caused by bird damage and other factors. The insulating layer formed by the cured polyurea has a fast curing time and does not form drips. The shape of the power components can be ignored and the parts that need to be insulated can be sprayed indiscriminately. The polyurea material has high thermal conductivity and insulation properties, has a good spraying effect, and can effectively adhere to the surface of power components such as cross-arms. DETAILED DESCRIPTION

[0026] [Corrected 16.12.2024 in accordance with Rule 26] The following will clearly and completely describe the technical solutions in the embodiments of the present invention. It is obvious that the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort shall fall within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the present invention.

[0028] It should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," and "disposed" should be understood broadly, for example, to mean fixedly connected or disposed, detachably connected or disposed, or integrally connected or disposed. A person of ordinary skill in the art will understand the specific meanings of the above terms in this patent based on the specific circumstances.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "several" means two or more unless otherwise specifically defined. Example

[0030] 1 to 5 , this embodiment provides a method for preparing an insulating spray coating material on the cross arm side of a transmission tower, including the following steps:

[0031] Step 1. Synthesis of isocyanate prepolymer component A: Take 75 mmol of 4,4-methylenebis(phenyl isocyanate) and 11.25 mmol of polyether polyol and add them to a condensing reflux magnetic stirring device and react for 3 hours at 80°C under a nitrogen atmosphere to form an isocyanate prepolymer. Component A selects the reaction raw materials 4,4-methylenebis(phenyl isocyanate) and polyether polyol and reacts them according to the required molar ratio. Stability during the reaction is ensured by using nitrogen protection to avoid moisture interference. The reaction temperature is controlled within the range of 80°C ± 5°C and the stirring rate is maintained at 300 rpm to ensure the uniformity and sufficiency of the reaction. The synthesized prepolymer needs to be tested by infrared spectroscopy (FTIR) to determine the degree of isocyanate group consumption to determine whether the reaction is complete. This step lays the foundation for the subsequent synthesis of the core material of the polyurea coating;

[0032] Step 2: Synthesis of the Amine Compound in Component B: 7.6 mmol of 3,3-dichloro-4,4-diaminodiphenylmethane and 3.25 mmol of amino-terminated polyether were added to 15 ml of a silane coupling agent. Five fillers (1 part by mass equals 0.5 g) were added, each in a kaolin:boron nitride ratio of 1:1, 1.2:1, 1.5:1, 1:1.5, and 1:1.2, respectively. The mixture was stirred for 5 hours. The resulting Component B, containing five different filler ratios, was designated 1#, 2#, 3#, 4#, and 5#. The synthesis of the amine compound involved the reaction of 3,3-dichloro-4,4-diaminodiphenylmethane and amino-terminated polyether. An appropriate proportion of silane coupling agent (3-aminopropyltriethoxysilane) was added during the reaction to enhance the bonding between the filler and the matrix. To ensure the filler's full potential in the reaction, kaolin and boron nitride were mixed and stirred for 5 hours using varying mass ratios. The key to this step is to optimize the filler ratio through mechanical and electrical performance tests to ensure uniform dispersion of the filler in the final material and improve the overall performance of the material;

[0033] Step 3: Add components A and B in appropriate proportions to the material pipe of the crossarm spray gun. Connect the spray gun to an air compressor with a pressure greater than 600 kPa and spray the mixture onto the surface of the aluminum plate, which has been cleaned with anhydrous ethanol. After spraying, the material solidifies at room temperature and the spraying is repeated two to three times to increase the coating thickness, forming a polyurea resin coating. During the spraying process, components A and B are mixed in a specific ratio to ensure reactivity and stability. A spray gun with a pressure greater than 600 kPa is used to ensure that the mixture is evenly sprayed onto the aluminum plate surface during the spraying process. The nozzle diameter and spray distance of the spray gun must be precisely controlled during spraying to ensure a uniform coating thickness. After spraying, the polyurea coating is cured at room temperature for 24 hours and then heat-cured at 120°C for 2 hours to ensure the chemical structure of the polyurea coating is stable and enhance its aging and corrosion resistance.

[0034] In step 1, the polyether polyol in component A has a molecular weight of 4000 g / mol, and the nitrogen used is 99.99% pure. This polyether polyol molecular weight of 4000 g / mol ensures sufficient molecular chain length, thereby improving the mechanical properties and durability of the polyurea coating. Furthermore, the nitrogen purity is controlled at 99.99% to ensure that no oxygen or moisture interferes with the polyurea synthesis during the reaction, further improving the stability and reliability of the final product.

[0035] In step 2, the amine compound (component B) and the silane coupling agent are mixed in a 5:1 ratio. This 5:1 ratio ensures good chemical bonding between the filler and the matrix during the reaction. This ratio enhances the interfacial adhesion of the polyurea coating, improving its mechanical strength and chemical resistance. The silane coupling agent improves the compatibility between the filler and the resin matrix, thereby enhancing the overall performance of the coating.

[0036] In step 1, the reaction temperature was maintained at 80°C ± 5°C and the stirring rate was 300 rpm. The reaction temperature was strictly controlled within the range of 80°C ± 5°C to ensure that the reaction of isocyanate and polyether polyol was completely free from excessively high or low temperatures affecting the reaction rate. The stirring rate was set at 300 rpm during the reaction to ensure that the reactants were fully mixed and promoted the reaction. In step 2, the mass ratios of five different kaolin and boron nitride fillers were adjusted based on actual test results to achieve the best mechanical and electrical insulation properties. The mass ratios of the fillers were flexibly adjusted based on experimental results to optimize the performance of the material. Testing of different filler ratios ensured that the coating had good electrical and mechanical properties.

[0037] After spraying in step 3, the aluminum plate undergoes a 24-hour room-temperature curing treatment followed by a 2-hour heat curing treatment at 120°C to ensure that the coating's weather resistance and electrical insulation properties meet the expected standards. The aluminum plate undergoes a 24-hour room-temperature curing treatment to ensure initial curing of the coating and avoid unevenness or poor adhesion. A subsequent heat curing treatment at 120°C for 2 hours further enhances the coating's hardness and heat resistance, ensuring the polyurea coating maintains stable performance under high voltage and harsh environmental conditions. This heat curing process further cross-links the molecular structure, enhancing the coating's weather resistance and aging resistance.

[0038] In step 1, the molecular weight of the polyether polyol should be 4000 g / mol and contain at least four hydroxyl groups. The isocyanate molar ratio should be controlled at 0.67:1 to ensure the reactivity of the prepolymer. The nitrogen used during the reaction should be 99.99% pure to ensure that the reaction environment is free of moisture or impurities to prevent them from affecting the reaction. The reaction temperature should be strictly controlled within the range of 80°C ± 5°C. Excessive temperatures can lead to excessive reactions and affect product quality, while excessively low temperatures can result in incomplete reactions. The molecular weight of the polyether polyol should be 4000 g / mol and contain at least four hydroxyl groups. This molecular structure ensures high reactivity and a stable polyurea coating. The molecular ratio of isocyanate to polyether polyol should be strictly controlled at 0.67:1 to ensure complete reaction and avoid excess isocyanate groups that could lead to incomplete reaction. Using nitrogen with a purity of 99.99% further ensures a smooth reaction and prevents moisture or oxygen from affecting the reaction rate.

[0039] In step 1, the stirring rate is controlled at 300 rpm to ensure thorough mixing of the reactants and avoid localized overheating or underheating. The reaction time is controlled to 3 hours, during which component A will completely react to form an isocyanate prepolymer with high viscosity and appropriate reactivity. After the reaction, the product should be cooled and initially analyzed to ensure that its molecular structure meets the requirements. Infrared spectroscopy (FTIR) analysis can be used to monitor isocyanate group consumption and ensure the quality of the prepolymer. A stirring rate of 300 rpm helps ensure uniform mixing of the raw materials, avoids reactant precipitation, and thus increases the reaction rate. A 3-hour reaction time ensures complete reaction of component A. FTIR and other methods can be used to verify the reaction results and ensure that the molecular structure meets design requirements, providing reliable raw material support for subsequent batching and spraying.

[0040] In step 2, the purity of the amine compound 3,3-dichloro-4,4-diaminodiphenylmethane must reach over 99% to ensure complete reaction and stability of the final product. Filler selection: The mass ratio of kaolin to boron nitride should be adjusted based on experimental test results. Mechanical and electrical performance tests are required to determine the optimal ratio. Stirring should be performed under nitrogen to prevent the negative impact of moisture and oxygen in the air on the reaction. The stirring time should be 5 hours to ensure complete reaction and sufficient reaction between the filler and the amine compound. A magnetic stirrer or high-shear mixer is recommended to ensure material uniformity. The type of silane coupling agent used is 3-aminopropyltriethoxysilane, and the mass of the coupling agent should be 5% of the total reactants.

[0041] In step 3, the mass ratio of component A to component B should be controlled between 1:1.05 and 1:1.2 to ensure the proper curing speed and performance stability of the resin. This ratio should be fine-tuned based on environmental conditions (such as humidity and temperature). During spraying, the pressure should be greater than 600 kPa to ensure thorough mixing of components A and B in the spray gun. The nozzle diameter of the spray gun should be 2 mm, and the spraying distance should be 150 mm ± 10 mm. Spraying should be uniform and continuous to avoid areas where the coating is too thick or too thin. The sprayed aluminum plate should be cured at room temperature for 24 hours to ensure surface dryness and curing. The temperature should not exceed 30°C during the curing process to prevent high temperatures from degrading the material. After 24 hours of room temperature curing, the aluminum plate should be placed in a 120°C oven for 2 hours to stabilize the molecular structure of the polyurea coating and enhance its anti-aging properties. The cured coating thickness should reach 200 μm to 300 μm to ensure good electrical insulation and mechanical strength.

[0042] A performance test method for an insulation spray material on the cross arm side of a transmission tower, including the following test method S1: Electrical performance test:

[0043] Insulation resistance test: Use a high-voltage insulation resistance tester (test voltage is 5000V) to test the insulation resistance of the coating to ensure it is not less than 10^9 Ω·m;

[0044] Dielectric strength test: The dielectric strength of the coating is measured using the electrical breakdown test method (IEC 60243-1 standard) under standard test conditions and is required to be no less than 25kV / mm;

[0045] S2: Mechanical properties test: Tensile strength test: Use a tensile testing machine to test the tensile strength of the polyurea coating, which is required to be above 15 MPa;

[0046] Hardness test: Use Shore A hardness tester to test the coating surface hardness should reach 75~85 degrees;

[0047] S3: Weathering test: Place the coating sample in an accelerated aging test chamber (UV radiation, temperature and humidity cycling) for 300 hours. After the test, check the coating for cracks, peeling, or color changes.

[0048] In specific use, the above equipment reacts isocyanate (NCO) with the hydroxyl (OH) groups in the polyether polyol to form a polyurethane prepolymer. This reaction is a typical isocyanate-alcohol reaction. Nitrogen (99.99% purity) in the reaction atmosphere eliminates moisture and oxygen interference, ensuring smooth reaction and preventing hydrolysis. The temperature is controlled within 80°C ± 5°C, and the stirring rate is 300 rpm, ensuring uniform mixing of the reactants and complete reaction. Infrared spectroscopy (FTIR) is used to monitor the extent of isocyanate group consumption to determine reaction completion. The characteristic absorption peak of the isocyanate group in the FTIR spectrum (approximately 2270 cm⁻¹) gradually disappears as the reaction proceeds. 3,3-Dichloro-4,4-diaminodiphenylmethane reacts with the amino-terminated polyether to form an amino compound. This reaction is an addition reaction between isocyanate and amino groups, providing the basis for the formation of the polyurea resin. Kaolin and boron nitride fillers are mixed in varying mass ratios. These fillers can improve the mechanical strength, heat resistance, and electrical insulation properties of the final coating. The addition of a silane coupling agent strengthens the bond between the filler and the resin matrix, improving the overall performance of the composite material. The filler and amine compound are stirred for 5 hours to ensure a uniform reaction and good dispersion of the filler in the matrix material. Components A and B are mixed in proportion and evenly sprayed onto the aluminum plate surface using a spray gun. During the spraying process, the nozzle diameter of the spray gun is 2mm and the spraying distance is 150mm±10mm to ensure uniformity and consistency of the coating. After spraying, the coating is first cured at room temperature for 24 hours to ensure surface dryness and initial curing. Then use a 120℃ oven for heat curing for 2 hours to further enhance the hardness and heat resistance of the coating. After heat curing, the molecular structure of the polyurea coating is further cross-linked to enhance the mechanical strength, aging resistance and corrosion resistance of the coating. Insulation resistance test: Use a high-voltage insulation resistance tester to test whether the insulation resistance of the coating is not less than 10^9Ω·m. Dielectric strength test: According to the IEC60243-1 standard, the dielectric strength of the coating is required to be not less than 25kV / mm. Tensile strength test: The tensile strength of the coating is tested by a tensile testing machine and is required to reach more than 15MPa. Hardness test: Use a Shore A hardness tester to test the surface hardness of the coating. The hardness is required to be in the range of 75~85 degrees. Ultraviolet and temperature and humidity cycling: Use an accelerated aging test chamber to perform a 300-hour weathering test on the coating to check whether the coating has cracks, peeling or color changes.

[0049] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above-described embodiments. The above-described embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and modifications are possible without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an insulating spray material for a transmission tower cross arm, characterized in that: The following steps are involved: Step 1: Synthesis of isocyanate prepolymer component A: 75 mmol of 4,4-methylenebis(phenyl isocyanate) and 11.25 mmol of polyether polyol were added to a reflux magnetic stirring apparatus and reacted at 80°C under a nitrogen atmosphere for 3 hours; Step 2, synthesis of amine compound of component B: 7.6 mmol of 3,3-dichloro-4,4-diaminodiphenylmethane and 3.25 mmol of amino-terminated polyether were added to 15 ml of silane coupling agent and five fillers with a mass ratio of kaolin: boron nitride of 1:1, 1.2:1, 1.5:1, 1:1.5, and 1:1.2 were added (1 mass part in each ratio is 0.5 g) and mixed and stirred for 5 hours to obtain five B components with different mass ratios of fillers, named 1#, 2#, 3#, 4#, and 5# respectively; Step 3: Add component A and component B in appropriate proportions into the material pipe of the cross-arm spray gun and connect the spray gun to an air compressor with a pressure of more than 600 kPa to spray the mixture onto the surface of the aluminum plate cleaned with anhydrous ethanol. After spraying, the material solidifies at room temperature and the spraying is repeated 2 to 3 times to increase the thickness of the coating to form a polyurea resin coating.

2. The preparation method of the insulation spraying material for the cross arm side of a transmission tower according to claim 1, characterized in that: The molecular weight of the polyether polyol in component A in step 1 is 4000 g / mol and the purity of the nitrogen used is 99.99%.

3. The preparation method of the insulation spraying material for the cross arm side of a transmission tower according to claim 2, characterized in that: The mixing ratio of the amine compound and the silane coupling agent in the B component in the step 2 is 5:

1.

4. The preparation method of the insulation spraying material for the cross arm side of a transmission tower according to claim 3, characterized in that: In step 1, the reaction temperature is maintained at 80° C.±5° C. and the stirring rate is 300 rpm. In step 2, the mass ratios of the five different kaolin and boron nitride fillers can be adjusted according to actual test results.

5. The preparation method of the insulation spraying material for the cross arm side of a transmission tower according to claim 4, characterized in that: The aluminum plate after spraying in step 3 needs to be cured at room temperature for 24 hours and then heat-cured at 120° C. for 2 hours.

6. The method for preparing the insulation spray material for the cross-arm side of a transmission tower according to claim 5, wherein: The molecular weight of the polyether polyol in step 1 should be 4000 g / mol. The molecular ratio of isocyanate containing at least 4 hydroxy groups should be controlled at 0.67:1 to ensure the reactivity of the prepolymer. The purity of nitrogen used during the reaction should be 99.99%. The reaction temperature should be strictly controlled within the range of 80°C ± 5°C.

7. The method of preparing the insulation spray material for the cross-arm side of a transmission tower according to claim 6, wherein: In step 1, the stirring rate is controlled at 300 rpm and the reaction time is controlled at 3 hours. After component A is completely reacted, a preliminary analysis is performed to ensure that its molecular structure meets the requirements. Infrared spectroscopy (FTIR) analysis can be used to detect the consumption of isocyanate groups.

8. The method of preparing the insulation spray material for the cross-arm side of a transmission tower according to claim 7, wherein: The purity of the amine compound 3,3-dichloro-4,4-diaminodiphenylmethane in step 2 reaches more than 99% to ensure the sufficiency of the reaction and the stability of the final product. The mass ratio of kaolin and boron nitride should be adjusted according to different experimental test results. Mechanical and electrical performance tests are required to determine the optimal ratio. Stirring is carried out under nitrogen protection for 5 hours to ensure complete reaction and sufficient reaction between the filler and the amine compound. A magnetic stirrer or a high shear stirrer is used. The type of silane coupling agent used is 3-aminopropyltriethoxysilane, and the mass of the coupling agent should be 5% of the total reactant mass.

9. The method for preparing the insulation spray material for the cross-arm side of a transmission tower according to claim 8, wherein: In the step 3, the mass ratio of component A to component B should be controlled between 1:1.05 and 1:1.

2. The ratio should be fine-tuned according to different environmental conditions (such as humidity, temperature, etc.). The pressure used during the spraying process should be greater than 600 kPa to ensure that components A and B can be fully mixed in the spray gun. The nozzle diameter of the spray gun is 2 mm. The spraying distance should be 150 mm ± 10 mm. The sprayed aluminum plate needs to be cured at room temperature for 24 hours to ensure surface drying and curing effect. During the curing process, the temperature should not exceed 30°C to avoid high temperature causing material performance degradation. After curing at room temperature for 24 hours, the aluminum plate is placed in a 120°C oven for heat curing for 2 hours to ensure the stability of the molecular structure of the polyurea coating and enhance its anti-aging properties. The thickness of the coating after curing should reach 200 μm~300 μm.

10. A method for testing the performance of an insulation spray material on the cross-arm side of a transmission tower according to any one of claims 1 to 9, characterized in that: The following test methods are included: S1: Electrical performance test: Insulation resistance test: Use a high-voltage insulation resistance tester (test voltage is 5000V) to test the insulation resistance of the coating to ensure it is not less than 10^9 Ω·m; Dielectric strength test: The dielectric strength of the coating is measured using the electrical breakdown test method (IEC 60243-1 standard) under standard test conditions and is required to be no less than 25kV / mm; S2: Mechanical properties test: Tensile strength test: Use a tensile testing machine to test the tensile strength of the polyurea coating, which is required to be above 15 MPa; Hardness test: Use Shore A hardness tester to test the coating surface hardness should reach 75~85 degrees; S3: Weathering test: Place the coating sample in an accelerated aging test chamber (UV radiation, temperature and humidity cycling) for 300 hours of weathering test to check whether the coating has cracks, peeling or color change.