Waterproof and anti-aging coating for porcelain insulator and preparation process thereof

Abstract

The present application relates to the technical field of paint, in particular to a kind of waterproof and ageing-resistant paint for porcelain insulator and its preparation process.The preparation process of a kind of waterproof and ageing-resistant paint for porcelain insulator includes: the preparation of aminomethyl silicone resin, the preparation of crosslinkable group-containing curing agent, the preparation of waterproof and ageing-resistant paint.The present application introduces active amino group into aminomethyl silicone resin, chemically crosslinks with epoxy group, forms organic-silicon integrated interpenetrating network, gives coating excellent mechanical strength, compactness, hydrophobicity and ultraviolet ageing resistance, solves the problem of easy pulverization of organic component.At the same time, the curing agent containing benzocyclobutene is compounded with 4,4'-diamino diphenyl methane to build a dense three-dimensional network structure, greatly improve the crosslinking density, significantly enhance the barrier ability of coating to water vapor, salt fog and dirt, realize long-acting waterproof and ageing-resistant protection.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a waterproof and aging-resistant coating for porcelain insulators and its preparation process. Background Technology

[0002] As a critical insulating support component in power transmission lines and substations, porcelain insulators directly impact the operational safety of the power grid due to their external insulation performance. During long-term outdoor operation, industrial contaminants, saline-alkali dust, and natural dust inevitably accumulate on the surface of porcelain insulators. Under high humidity conditions such as fog, dew, drizzle, or melting ice, the contaminant layer becomes damp, forming a conductive water film. This leads to a sharp increase in leakage current on the insulator surface, easily triggering pollution flashover accidents, causing large-scale power outages and significant economic losses. Therefore, coating the surface of porcelain insulators with high-performance protective coatings, endowing them with excellent hydrophobicity and weather resistance, is one of the most economical and effective means of preventing pollution flashover accidents.

[0003] Currently, the protective coatings used for porcelain insulators are mainly room temperature vulcanizing (RTV) silicone rubber coatings. RTV coatings, with their low surface energy and good hydrophobic migration properties due to the organosilicon backbone, can significantly improve the insulator's anti-flashover capability and also exhibit good UV aging resistance. However, RTV coatings also have significant drawbacks: their adhesion to the porcelain substrate is limited, the coating's mechanical strength is relatively low, and problems such as peeling, wear, and detachment easily occur after long-term operation; at the same time, the coating's density is insufficient, and its ability to block small molecules such as water vapor and salt spray needs improvement, limiting its service life and protective reliability in harsh environments such as high humidity and heavy pollution.

[0004] To overcome the aforementioned limitations of pure silicone coatings, researchers have attempted to introduce organic resins such as epoxy resins into silicone coating systems. Epoxy resins possess excellent adhesive strength and mechanical properties, but when used alone, they exhibit extremely poor weather resistance, are prone to photo-oxidation and chalking, and lose their protective function. Simple physical blending of the two often results in severe phase separation due to thermodynamic incompatibility, leading to a significant decrease in coating transparency, uniformity, and overall performance. Introducing reactive groups into the silicone molecular chain through chemical modification, enabling cross-linking with epoxy groups, is an effective way to solve compatibility issues and construct a uniform network. However, existing silicone-modified epoxy coatings generally suffer from insufficient cross-linking density, resulting in a relatively simple network structure that struggles to balance density and long-term weather resistance. The coating's waterproof performance, especially its long-term barrier against water vapor and salt spray, and its durability under extreme environments, remain unsatisfactory.

[0005] Therefore, in view of the shortcomings of the existing technology, a waterproof and aging-resistant coating for porcelain insulators and its preparation process are provided, which can build a long-lasting protective coating with excellent hydrophobicity, anti-flashover, water resistance and super weather resistance on the surface of porcelain insulators. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a waterproof and aging-resistant coating for porcelain insulators and its preparation process.

[0007] This invention provides a preparation process for a waterproof and aging-resistant coating for porcelain insulators, comprising: S1: Preparation of aminomethyl silicone resin; Add 25-35 parts by weight of dimethyldimethoxysilane, 45-55 parts by weight of methyltriethoxysilane, and 10-20 parts by weight of γ-aminopropyltriethoxysilane to 60-100 parts by weight of ethanol, stir and mix, add 22-32 parts by weight of deionized water dropwise at 70-80℃, react for 5-6 hours, cool, remove the solvent by vacuum distillation, add anhydrous ethanol to adjust the solid content to 40-50%, and obtain an aminomethyl silicone resin solution. S2: Preparation of curing agents containing crosslinkable groups; Zinc powder was added to 10-20 parts by weight of deionized water, and the pH was adjusted to 5-6 with acetic acid. Then, 1-bromo-3,5-dinitrobenzene and ethanol were added, and the mixture was reacted at 80-85℃ for 3-4 hours under nitrogen protection. After post-treatment, intermediate product I was obtained. Intermediate product I and 2-3 parts by weight of di-tert-butyl dicarbonate were reacted in anhydrous ethanol and purified to obtain intermediate product II. Benzocyclobutene-4-boronic acid, intermediate product II, cesium carbonate and tetrakis(triphenylphosphine)palladium were mixed and refluxed in a toluene / ethanol / water mixed solvent. After extraction and purification, intermediate product III was obtained. Intermediate product III was dissolved in dichloromethane, and trifluoroacetic acid was added dropwise. The mixture was reacted at room temperature, neutralized and purified to obtain a curing agent containing crosslinkable groups. S3: Preparation of waterproof and aging-resistant coatings; A waterproof and aging-resistant coating is prepared by mixing 80-100 parts by weight of an aminomethyl silicone resin solution with a solid content of 40-50%, 5-15 parts by weight of bisphenol A epoxy resin, 5-15 parts by weight of epoxy acrylic resin, 5-15 parts by weight of butyl acetate, 5-10 parts by weight of cyclohexanone, 5-15 parts by weight of PPS resin micro powder, 8-10 parts by weight of a curing agent mixture, 3-8 parts by weight of hydrophobic fumed silica, 0.5-2 parts by weight of an ultraviolet absorber, 0.1-0.5 parts by weight of a leveling agent, and 0.1-0.3 parts by weight of a defoamer.

[0008] As a preferred aspect, S1: the preparation of aminomethyl silicone resin specifically includes the following steps: S1.1: Add 25-35 parts by weight of dimethyldimethoxysilane, 45-55 parts by weight of methyltriethoxysilane, and 10-20 parts by weight of γ-aminopropyltriethoxysilane to 60-100 parts by weight of ethanol, and stir and mix at 400-500 rpm for 20-30 min to obtain a mixture; S1.2: Place the mixture in an oil bath and stir at 400-500 rpm for 20-30 min. Then, add 22-32 parts by weight of deionized water at 70-80℃. After the addition is complete, continue the reaction for 5-6 h. After the reaction is complete, cool to room temperature to obtain the crude product of aminomethyl silicone resin. S1.3: The crude aminomethyl silicone resin product is subjected to vacuum distillation until no distillate is obtained. Then anhydrous ethanol is added to adjust the solid content to 40-50%, and the mixture is stirred evenly to obtain an aminomethyl silicone resin solution.

[0009] As a preferred aspect, the dropping rate of deionized water in step S1.2 is 2-3 mL / min.

[0010] As a preferred aspect, the vacuum distillation in step S1.3 is carried out at 60-70℃ and -0.09 to -0.1MPa.

[0011] As a preferred aspect, S2: the preparation of a curing agent containing crosslinkable groups specifically includes the following steps: S2.1: Add 2-4 parts by weight of zinc powder to 10-20 parts by weight of deionized water, stir and mix, then add acetic acid to adjust the pH to 5-6, then add 1 part by weight of 1-bromo-3,5-dinitrobenzene and 5-10 parts by weight of ethanol, evacuate and purge with nitrogen 3-5 times, then heat to 80-85℃ and react for 3-4 hours, then add potassium hydroxide to adjust the pH to neutral, filter, remove the solvent under reduced pressure, add 10-15 parts by weight of deionized water and 10-15 parts by weight of ethyl acetate to the residue, extract and separate the liquid, dry with anhydrous magnesium sulfate, and evaporate the solvent to obtain intermediate product I; S2.2: Dissolve intermediate product I and 2-3 parts by weight of di-tert-butyl dicarbonate in 5-10 parts by weight of anhydrous ethanol, stir at 300-500 rpm for 24-25 h at room temperature. After the reaction is complete, remove the solvent by rotary evaporation, then purify by chromatography on silica gel, remove the solvent under reduced pressure to obtain intermediate product II. S2.3: Mix 0.4-0.6 parts by weight of monomer benzocyclobutene-4-boronic acid, 1 part by weight of intermediate product II, and 1.5-2.5 parts by weight of cesium carbonate, then add 0.03-0.08 parts by weight of tetra-triphenylphosphine palladium, followed by 5-12 parts by weight of toluene, 2-5 parts by weight of ethanol, and 2-5 parts by weight of deionized water. Vacuum the mixture and purge it with nitrogen 3-5 times. Then, heat it under reflux at 80-85°C for 24-25 hours. After the reaction is complete, cool it to room temperature, add 15-25 parts by weight of ethyl acetate and 15-25 parts by weight of deionized water for extraction, wash the organic phase with water 3-5 times, dry it with anhydrous magnesium sulfate, filter it, remove the solvent under reduced pressure, and finally purify it by chromatography on silica gel to obtain intermediate product III. S2.4: Add intermediate product III to 5-10 parts by weight of dichloromethane, then stir and mix at 300-500 rpm for 20-30 min. Then add 3-5 parts by weight of trifluoroacetic acid dropwise, and stir and react at 500-600 rpm at room temperature for 4-5 h. After the reaction is complete, add sodium hydroxide to adjust the pH to neutral, wash with water 3-5 times, dry, remove the solvent under reduced pressure, and purify by chromatography on silica gel to obtain a curing agent containing crosslinkable groups.

[0012] As a preferred aspect, S3: the preparation of the waterproof and aging-resistant coating specifically includes the following steps: S3.1: At 400-600 rpm, add 5-15 parts by weight of bisphenol A epoxy resin, 5-15 parts by weight of epoxy acrylate resin, 5-15 parts by weight of butyl acetate and 5-10 parts by weight of cyclohexanone to 80-100 parts by weight of the above aminomethyl silicone resin solution with a solid content of 40-50%, and stir and mix at 400-600 rpm for 20-30 min to obtain a resin mixture; S3.2: Under high-speed dispersion at 800-1200 rpm, add 5-15 parts by weight of PPS resin micro powder with a particle size ≤10μm to the above resin mixture, disperse for 20-30 min, then add 8-10 parts by weight of curing agent mixture, and continue stirring at 600-800 rpm for 30-60 min to obtain mixed slurry. S3.3: Under stirring at 800-1200 rpm, add 3-8 parts by weight of hydrophobic fumed silica, 0.5-2 parts by weight of ultraviolet absorber, 0.1-0.5 parts by weight of leveling agent and 0.1-0.3 parts by weight of defoamer to the mixed slurry, disperse for 20-30 minutes, and then transfer to a sand mill to grind to a fineness ≤20μm to obtain a waterproof and aging-resistant coating.

[0013] As a preferred aspect, the curing agent mixture in step S3.2 is composed of a curing agent containing crosslinkable groups, 4,4'-diaminodiphenylmethane, and anhydrous ethanol in a mass ratio of 1:(2-4):(3-5).

[0014] As a preferred aspect, the ultraviolet absorber in step S3.3 is specifically 2-(2H-benzotriazol-2-yl)-4,6-bis(1,1-dimethylpropyl)phenol, the leveling agent is specifically polyether-modified polydimethylsiloxane, and the defoamer is specifically polydimethylsiloxane.

[0015] The present invention also provides a waterproof and aging-resistant coating for porcelain insulators, which is prepared by the preparation process of any one of the waterproof and aging-resistant coatings for porcelain insulators described in any one of the claims.

[0016] The present invention has the following advantages: 1. This invention introduces active amino groups into the aminomethyl silicone resin added to the waterproof and aging-resistant coating. These amino groups can serve as reaction sites, undergoing ring-opening crosslinking reactions with the epoxy groups and curing agent system in the formulation. This results in a highly integrated interpenetrating network between the organic resin and the silicone resin skeleton, thereby endowing the coating with excellent mechanical strength, density, and durability. Furthermore, the low intrinsic surface energy of the silicone resin is the basis for the excellent initial hydrophobicity and anti-flashover properties of the entire coating. At the same time, the silicone backbone structure endows the coating with excellent UV aging resistance, solving the problem of easy chalking of organic components such as epoxy resin, and ensuring that the hydrophobicity and protective function of the coating do not rapidly decline during long-term outdoor operation.

[0017] 2. The curing agent added in this invention is a compound of a curing agent containing crosslinkable groups and 4,4'-diaminodiphenylmethane. 4,4'-diaminodiphenylmethane, as an aromatic diamine, reacts with epoxy groups to form a conventional epoxy-amine crosslinking network. After the two are compounded, the curing agent containing crosslinkable groups can form an interpenetrating dense three-dimensional network structure with 4,4'-diaminodiphenylmethane inside the coating, which greatly increases the crosslinking density, strengthens the barrier ability against water vapor, salt spray and dirt, and significantly improves the waterproof performance of the coating. Attached Figure Description

[0018] Figure 1 The preparation process of the waterproof and aging-resistant coating for porcelain insulators used in the embodiments of the present invention is described. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention.

[0020] Synthetic route of aminomethyl silicone resin:

[0021] Synthetic route of curing agents containing crosslinkable groups:

[0022] In the examples, the ultraviolet absorber is specifically 2-(2H-benzotriazol-2-yl)-4,6-bis(1,1-dimethylpropyl)phenol, the leveling agent is specifically polyether-modified polydimethylsiloxane, and the defoamer is specifically polydimethylsiloxane.

[0023] Example 1: A preparation process for a waterproof and aging-resistant coating for porcelain insulators, referring to... Figure 1 ,include: S1: Preparation of aminomethyl silicone resin S1.1: Add 25 parts by weight of dimethyldimethoxysilane, 45 parts by weight of methyltriethoxysilane, and 10 parts by weight of γ-aminopropyltriethoxysilane to 60 parts by weight of ethanol, and stir and mix at 400 rpm for 20 min to obtain a mixture; S1.2: Place the mixture in an oil bath and stir at 400 rpm for 20 min. Then, add 22 parts by weight of deionized water at 70 °C at a dropping rate of 2 mL / min. After the addition is complete, continue the reaction for 5 h. After the reaction is complete, cool to room temperature to obtain the crude product of aminomethyl silicone resin. S1.3: The crude aminomethyl silicone resin product was distilled under reduced pressure at 60℃ and -0.09MPa until no distillate was obtained. Then anhydrous ethanol was added to adjust the solid content to 40%, and the mixture was stirred evenly to obtain an aminomethyl silicone resin solution. S2: Preparation of curing agents containing crosslinkable groups S2.1: Add 2 parts by weight of zinc powder to 10 parts by weight of deionized water, stir and mix, then add acetic acid to adjust the pH to 5, then add 1 part by weight of 1-bromo-3,5-dinitrobenzene and 5 parts by weight of ethanol, evacuate and purge with nitrogen 3 times, then heat to 80℃ and react for 3 hours, then add potassium hydroxide to adjust the pH to neutral, filter, remove the solvent under reduced pressure, add 10 parts by weight of deionized water and 10 parts by weight of ethyl acetate to the residue, extract and separate the liquid, dry with anhydrous magnesium sulfate, and evaporate the solvent to obtain intermediate product I; S2.2: Intermediate product I and 2 parts by weight of di-tert-butyl dicarbonate were dissolved in 5 parts by weight of anhydrous ethanol and stirred at 300 rpm for 24 h at room temperature. After the reaction was completed, the solvent was removed by rotary evaporation, and then purified by chromatography on silica gel. The solvent was removed under reduced pressure to obtain intermediate product II. S2.3: Mix 0.4 parts by weight of monomer benzocyclobutene-4-boronic acid, 1 part by weight of intermediate product II, and 1.5 parts by weight of cesium carbonate, then add 0.03 parts by weight of tetratriphenylphosphine palladium, followed by 5 parts by weight of toluene, 2 parts by weight of ethanol, and 2 parts by weight of deionized water. Vacuum the mixture and purge it with nitrogen three times. Then, heat it at 80°C under reflux for 24 hours. After the reaction is complete, cool it to room temperature, add 15 parts by weight of ethyl acetate and 15 parts by weight of deionized water for extraction, wash the organic phase three times with water, dry it with anhydrous magnesium sulfate, filter it, remove the solvent under reduced pressure, and finally purify it by chromatography on silica gel to obtain intermediate product III. S2.4: Add intermediate product III to 5 parts by weight of dichloromethane, then stir and mix at 300 rpm for 20 min, then add 3 parts by weight of trifluoroacetic acid, stir and react at 500 rpm for 4 h at room temperature. After the reaction is complete, add sodium hydroxide to adjust the pH to neutral, wash with water 3 times, dry, remove solvent under reduced pressure, and purify by chromatography on silica gel to obtain a curing agent containing crosslinkable groups. S3: Preparation of Waterproof and Aging-Resistant Coatings S3.1: At 400 rpm, add 5 parts by weight of bisphenol A epoxy resin, 5 parts by weight of epoxy acrylate resin, 5 parts by weight of butyl acetate and 5 parts by weight of cyclohexanone to 80 parts by weight of the above aminomethyl silicone resin solution with a solid content of 40%. Stir and mix at 400 rpm for 20 min to obtain a resin mixture. S3.2: Under high-speed dispersion at 800 rpm, add 5 parts by weight of PPS resin micro powder with a particle size ≤10 μm to the above resin mixture, disperse for 20 min, then add 8 parts by weight of curing agent mixture, and continue stirring at 600 rpm for 30 min to obtain mixed slurry. The curing agent mixture consists of a curing agent containing crosslinkable groups, 4,4'-diaminodiphenylmethane, and anhydrous ethanol in a mass ratio of 1:2:3; S3.3: Add 3 parts by weight of hydrophobic fumed silica, 0.5 parts by weight of ultraviolet absorber, 0.1 parts by weight of leveling agent and 0.1 parts by weight of defoamer to the mixed slurry under stirring at 800 rpm, disperse for 20 min, and then transfer to a sand mill to grind to a fineness of ≤20 μm to obtain a waterproof and aging-resistant coating.

[0024] Example 2: A preparation process for a waterproof and aging-resistant coating for porcelain insulators, see [link to example]. Figure 1 ,include: S1: Preparation of aminomethyl silicone resin S1.1: Add 35 parts by weight of dimethyldimethoxysilane, 55 parts by weight of methyltriethoxysilane, and 20 parts by weight of γ-aminopropyltriethoxysilane to 100 parts by weight of ethanol, and stir and mix at 500 rpm for 30 min to obtain a mixture; S1.2: Place the mixture in an oil bath and stir at 500 rpm for 30 min. Then, add 32 parts by weight of deionized water at 80 °C at a dropping rate of 3 mL / min. After the addition is complete, continue the reaction for 6 h. After the reaction is complete, cool to room temperature to obtain the crude product of aminomethyl silicone resin. S1.3: The crude aminomethyl silicone resin product was distilled under reduced pressure at 70℃ and -0.1MPa until no distillate was obtained. Then anhydrous ethanol was added to adjust the solid content to 50%, and the mixture was stirred evenly to obtain an aminomethyl silicone resin solution. S2: Preparation of curing agents containing crosslinkable groups S2.1: Add 4 parts by weight of zinc powder to 20 parts by weight of deionized water, stir and mix, then add acetic acid to adjust the pH to 6, then add 1 part by weight of 1-bromo-3,5-dinitrobenzene and 10 parts by weight of ethanol, evacuate and purge with nitrogen 5 times, then heat to 85℃ and react for 4 hours, then add potassium hydroxide to adjust the pH to neutral, filter, remove the solvent under reduced pressure, add 15 parts by weight of deionized water and 15 parts by weight of ethyl acetate to the residue, extract and separate the liquid, dry with anhydrous magnesium sulfate, and evaporate the solvent to obtain intermediate product I; S2.2: Intermediate product I and 3 parts by weight of di-tert-butyl dicarbonate were dissolved in 10 parts by weight of anhydrous ethanol and stirred at 500 rpm for 25 h at room temperature. After the reaction was completed, the solvent was removed by rotary evaporation, and then purified by chromatography on silica gel. The solvent was removed under reduced pressure to obtain intermediate product II. S2.3: Mix 0.6 parts by weight of monomer benzocyclobutene-4-boronic acid, 1 part by weight of intermediate product II, and 2.5 parts by weight of cesium carbonate, then add 0.08 parts by weight of tetra-triphenylphosphine palladium, followed by 12 parts by weight of toluene, 5 parts by weight of ethanol, and 5 parts by weight of deionized water. Vacuum the mixture and purge it with nitrogen five times. Then, heat it at 85°C under reflux for 25 hours. After the reaction is complete, cool it to room temperature, add 25 parts by weight of ethyl acetate and 25 parts by weight of deionized water for extraction, wash the organic phase five times with water, dry it with anhydrous magnesium sulfate, filter it, remove the solvent under reduced pressure, and finally purify it by chromatography on silica gel to obtain intermediate product III. S2.4: Add intermediate product III to 10 parts by weight of dichloromethane, then stir and mix at 500 rpm for 30 min, then add 5 parts by weight of trifluoroacetic acid, stir and react at 600 rpm for 5 h at room temperature. After the reaction is complete, add sodium hydroxide to adjust the pH to neutral, wash with water 5 times, dry, remove solvent under reduced pressure, and purify by chromatography on silica gel to obtain a curing agent containing crosslinkable groups. S3: Preparation of Waterproof and Aging-Resistant Coatings S3.1: At 600 rpm, 15 parts by weight of bisphenol A epoxy resin, 15 parts by weight of epoxy acrylate resin, 15 parts by weight of butyl acetate and 10 parts by weight of cyclohexanone were added sequentially to 100 parts by weight of the above aminomethyl silicone resin solution with a solid content of 50%. The mixture was stirred at 600 rpm for 30 min to obtain a resin mixture. S3.2: Under high-speed dispersion at 1200 rpm, add 15 parts by weight of PPS resin micro powder with a particle size ≤10 μm to the above resin mixture, disperse for 30 min, then add 10 parts by weight of curing agent mixture, and continue stirring at 800 rpm for 60 min to obtain mixed slurry. The curing agent mixture consists of a curing agent containing crosslinkable groups, 4,4'-diaminodiphenylmethane, and anhydrous ethanol in a mass ratio of 1:4:5; S3.3: Add 8 parts by weight of hydrophobic fumed silica, 2 parts by weight of ultraviolet absorber, 0.5 parts by weight of leveling agent and 0.3 parts by weight of defoamer to the mixed slurry under stirring at 1200 rpm, disperse for 30 min, and then transfer to a sand mill to grind to a fineness of ≤20 μm to obtain a waterproof and aging-resistant coating.

[0025] Example 3: A preparation process for a waterproof and aging-resistant coating for porcelain insulators, see [link to example]. Figure 1 ,include: S1: Preparation of aminomethyl silicone resin S1.1: Add 30 parts by weight of dimethyldimethoxysilane, 40 parts by weight of methyltriethoxysilane, and 15 parts by weight of γ-aminopropyltriethoxysilane to 80 parts by weight of ethanol, and stir and mix at 450 rpm for 25 min to obtain a mixture; S1.2: Place the mixture in an oil bath and stir at 450 rpm for 25 min. Then, add 27 parts by weight of deionized water at 75 °C at a dropping rate of 2.5 mL / min. After the addition is complete, continue the reaction for 5.5 h. After the reaction is complete, cool to room temperature to obtain the crude product of aminomethyl silicone resin. S1.3: The crude aminomethyl silicone resin product was distilled under reduced pressure at 65℃ and -0.095MPa until no distillate was obtained. Then anhydrous ethanol was added to adjust the solid content to 45%, and the mixture was stirred evenly to obtain an aminomethyl silicone resin solution. S2: Preparation of curing agents containing crosslinkable groups S2.1: Add 3 parts by weight of zinc powder to 15 parts by weight of deionized water, stir and mix, then add acetic acid to adjust the pH to 5.5, then add 1 part by weight of 1-bromo-3,5-dinitrobenzene and 7.5 parts by weight of ethanol, evacuate and purge with nitrogen 4 times, then heat to 82.5℃ and react for 3.5 h, then add potassium hydroxide to adjust the pH to neutral, filter, remove the solvent under reduced pressure, add 12.5 parts by weight of deionized water and 12.5 parts by weight of ethyl acetate to the residue, extract and separate, dry with anhydrous magnesium sulfate, and evaporate the solvent to obtain intermediate product I; S2.2: Intermediate product I and 2.5 parts by weight of di-tert-butyl dicarbonate were dissolved in 7.5 parts by weight of anhydrous ethanol and stirred at 400 rpm for 24.5 h at room temperature. After the reaction was completed, the solvent was removed by rotary evaporation, and then purified by chromatography on silica gel. The solvent was removed under reduced pressure to obtain intermediate product II. S2.3: Mix 0.5 parts by weight of monomer benzocyclobutene-4-boronic acid, 1 part by weight of intermediate product II, and 2 parts by weight of cesium carbonate, then add 0.055 parts by weight of tetratriphenylphosphine palladium, followed by 8.5 parts by weight of toluene, 3.5 parts by weight of ethanol, and 3.5 parts by weight of deionized water. Vacuum the mixture and purge it with nitrogen four times. Then, heat it under reflux at 82.5°C for 24.5 h. After the reaction is complete, cool it to room temperature, add 20 parts by weight of ethyl acetate and 20 parts by weight of deionized water for extraction, wash the organic phase four times with water, dry it with anhydrous magnesium sulfate, filter it, remove the solvent under reduced pressure, and finally purify it by chromatography on silica gel to obtain intermediate product III. S2.4: Add intermediate product III to 7.5 parts by weight of dichloromethane, then stir and mix at 400 rpm for 25 min, then add 4 parts by weight of trifluoroacetic acid dropwise, and stir and react at 550 rpm for 4.5 h at room temperature. After the reaction is complete, add sodium hydroxide to adjust the pH to neutral, wash with water 4 times, dry, remove solvent under reduced pressure, and purify by chromatography on silica gel to obtain a curing agent containing crosslinkable groups. S3: Preparation of Waterproof and Aging-Resistant Coatings S3.1: At 500 rpm, 10 parts by weight of bisphenol A epoxy resin, 10 parts by weight of epoxy acrylate resin, 10 parts by weight of butyl acetate and 7.5 parts by weight of cyclohexanone were added sequentially to 90 parts by weight of the above aminomethyl silicone resin solution with a solid content of 45%. The mixture was stirred at 500 rpm for 25 min to obtain a resin mixture. S3.2: Under high-speed dispersion at 1000 rpm, add 10 parts by weight of PPS resin micro powder with a particle size ≤10 μm to the above resin mixture, disperse for 25 min, then add 9 parts by weight of curing agent mixture, and continue stirring at 700 rpm for 45 min to obtain mixed slurry. The curing agent mixture consists of a curing agent containing crosslinkable groups, 4,4'-diaminodiphenylmethane, and anhydrous ethanol in a mass ratio of 1:3:4; S3.3: Add 5.5 parts by weight of hydrophobic fumed silica, 1.2 parts by weight of ultraviolet absorber, 0.3 parts by weight of leveling agent and 0.2 parts by weight of defoamer to the mixed slurry under stirring at 1000 rpm, disperse for 25 min, and then transfer to a sand mill to grind to a fineness of ≤20 μm to obtain a waterproof and aging-resistant coating.

[0026] Comparative Example 1 differs from Example 1 in that step S1 is removed, and the aminomethyl silicone resin solution with a solid content of 40% in step S3.1 is replaced with an equal amount of vulcanized silicone rubber solution with a solid content of 40%. The remaining steps are unchanged in preparing the waterproof and aging-resistant coating, and it is referred to as Comparative Example 1.

[0027] Comparative Example 2 differs from Example 1 in that step S2 is removed, and the curing agent containing crosslinkable groups in step S3.1 is replaced with 4,4'-diaminodiphenylmethane, while the remaining steps remain unchanged to prepare a waterproof and aging-resistant coating. This is referred to as Comparative Example 2.

[0028] The waterproof and aging-resistant coatings prepared in Examples 1-3 and Comparative Examples 1-2 were respectively applied to porcelain insulator test pieces by spraying. After surface drying at room temperature for 0.5 hours, they were cured with the following curing parameters: 40℃ / 1h, 58℃ / 2h, 96℃ / 3h, and 122℃ / 2h. The dry film thickness was controlled to be (60±10) μm.

[0029] Water contact angle: using the seat drop method with deionized water, 5 points were measured per piece and the average was taken. Water absorption rate: calculated according to GB / T1738, after soaking at room temperature for 24 hours and weighing. Salt spray resistance: according to GB / T1771, 5% NaCl, 35℃, continuous spraying for 1000 hours, observing blistering and corrosion.

[0030] Waterproof and salt spray resistance properties of Examples 1-3 and Comparative Examples 1-2 were tested, and the test results are shown in Table 1.

[0031] Table 1. Performance test results of Examples 1-3 and Comparative Examples 1-2

[0032] As can be seen from the data in Table 1, Comparative Example 1 uses vulcanized silicone rubber instead of aminomethyl silicone resin. Due to the lack of chemical crosslinking points between active amino and epoxy groups, an integrated network cannot be formed, resulting in a decrease in coating density and poor waterproof and salt spray resistance. Comparative Example 2 is entirely cured with 4,4'-diaminodiphenylmethane, which only forms a single epoxy-amine crosslinking network and lacks a dense three-dimensional network structure, resulting in significantly insufficient waterproof barrier ability.

[0033] UV aging: The surface was irradiated with a UV-A lamp at 60°C for 1000 hours. After removal, the degree of surface powdering was observed and the water contact angle was measured.

[0034] Adhesion: Rated according to GB / T9286, using the cross-cut adhesion test.

[0035] UV aging and adhesion tests were performed on Examples 1-3. The tests were conducted three times, and the average value was taken. The test results are shown in Table 2.

[0036] Table 2. Results of UV aging and adhesion tests in Examples 1-3

[0037] As can be seen from the data in Table 2, the waterproof and aging-resistant coating prepared by this invention has good adhesion and aging resistance.

[0038] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Parts not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A preparation process for a waterproof and aging-resistant coating for porcelain insulators, characterized in that, include: S1: Preparation of aminomethyl silicone resin; Add 25-35 parts by weight of dimethyldimethoxysilane, 45-55 parts by weight of methyltriethoxysilane, and 10-20 parts by weight of γ-aminopropyltriethoxysilane to 60-100 parts by weight of ethanol, stir and mix, add 22-32 parts by weight of deionized water dropwise at 70-80℃, react for 5-6 hours, cool, remove the solvent by vacuum distillation, add anhydrous ethanol to adjust the solid content to 40-50%, and obtain an aminomethyl silicone resin solution. S2: Preparation of curing agents containing crosslinkable groups; Zinc powder was added to 10-20 parts by weight of deionized water, and the pH was adjusted to 5-6 with acetic acid. Then, 1-bromo-3,5-dinitrobenzene and ethanol were added, and the mixture was reacted at 80-85℃ for 3-4 hours under nitrogen protection. After post-treatment, intermediate product I was obtained. Intermediate product I and 2-3 parts by weight of di-tert-butyl dicarbonate were reacted in anhydrous ethanol and purified to obtain intermediate product II. Benzocyclobutene-4-boronic acid, intermediate product II, cesium carbonate and tetrakis(triphenylphosphine)palladium were mixed and refluxed in a toluene / ethanol / water mixed solvent. After extraction and purification, intermediate product III was obtained. Intermediate product III was dissolved in dichloromethane, and trifluoroacetic acid was added dropwise. The mixture was reacted at room temperature, neutralized and purified to obtain a curing agent containing crosslinkable groups. S3: Preparation of waterproof and aging-resistant coatings; A waterproof and aging-resistant coating is prepared by mixing 80-100 parts by weight of an aminomethyl silicone resin solution with a solid content of 40-50%, 5-15 parts by weight of bisphenol A epoxy resin, 5-15 parts by weight of epoxy acrylic resin, 5-15 parts by weight of butyl acetate, 5-10 parts by weight of cyclohexanone, 5-15 parts by weight of PPS resin micro powder, 8-10 parts by weight of a curing agent mixture, 3-8 parts by weight of hydrophobic fumed silica, 0.5-2 parts by weight of an ultraviolet absorber, 0.1-0.5 parts by weight of a leveling agent, and 0.1-0.3 parts by weight of a defoamer.

2. The preparation process of a waterproof and aging-resistant coating for porcelain insulators according to claim 1, characterized in that, S1: The preparation of aminomethyl silicone resin specifically includes the following steps: S1.1: Add 25-35 parts by weight of dimethyldimethoxysilane, 45-55 parts by weight of methyltriethoxysilane, and 10-20 parts by weight of γ-aminopropyltriethoxysilane to 60-100 parts by weight of ethanol, and stir and mix at 400-500 rpm for 20-30 min to obtain a mixture; S1.2: Place the mixture in an oil bath and stir at 400-500 rpm for 20-30 min. Then, add 22-32 parts by weight of deionized water at 70-80℃. After the addition is complete, continue the reaction for 5-6 h. After the reaction is complete, cool to room temperature to obtain the crude product of aminomethyl silicone resin. S1.3: The crude aminomethyl silicone resin product is subjected to vacuum distillation until no distillate is obtained. Then anhydrous ethanol is added to adjust the solid content to 40-50%, and the mixture is stirred evenly to obtain an aminomethyl silicone resin solution.

3. The preparation process of a waterproof and aging-resistant coating for porcelain insulators according to claim 1, characterized in that, In step S1.2, the deionized water is added at a rate of 2-3 mL / min.

4. The preparation process of a waterproof and aging-resistant coating for porcelain insulators according to claim 1, characterized in that, The vacuum distillation in step S1.3 is carried out at 60-70℃ and -0.09 to -0.1MPa.

5. The preparation process of a waterproof and aging-resistant coating for porcelain insulators according to claim 1, characterized in that, S2: Preparation of curing agents containing crosslinkable groups, specifically including the following steps: S2.1: Add 2-4 parts by weight of zinc powder to 10-20 parts by weight of deionized water, stir and mix, then add acetic acid to adjust the pH to 5-6, then add 1 part by weight of 1-bromo-3,5-dinitrobenzene and 5-10 parts by weight of ethanol, evacuate and purge with nitrogen 3-5 times, then heat to 80-85℃ and react for 3-4 hours, then add potassium hydroxide to adjust the pH to neutral, filter, remove the solvent under reduced pressure, add 10-15 parts by weight of deionized water and 10-15 parts by weight of ethyl acetate to the residue, extract and separate the liquid, dry with anhydrous magnesium sulfate, and evaporate the solvent to obtain intermediate product I; S2.2: Dissolve intermediate product I and 2-3 parts by weight of di-tert-butyl dicarbonate in 5-10 parts by weight of anhydrous ethanol, stir at 300-500 rpm for 24-25 h at room temperature. After the reaction is complete, remove the solvent by rotary evaporation, then purify by chromatography on silica gel, remove the solvent under reduced pressure to obtain intermediate product II. S2.3: Mix 0.4-0.6 parts by weight of monomer benzocyclobutene-4-boronic acid, 1 part by weight of intermediate product II, and 1.5-2.5 parts by weight of cesium carbonate, then add 0.03-0.08 parts by weight of tetra-triphenylphosphine palladium, followed by 5-12 parts by weight of toluene, 2-5 parts by weight of ethanol, and 2-5 parts by weight of deionized water. Vacuum the mixture and purge it with nitrogen 3-5 times. Then, heat it under reflux at 80-85°C for 24-25 hours. After the reaction is complete, cool it to room temperature, add 15-25 parts by weight of ethyl acetate and 15-25 parts by weight of deionized water for extraction, wash the organic phase with water 3-5 times, dry it with anhydrous magnesium sulfate, filter it, remove the solvent under reduced pressure, and finally purify it by chromatography on silica gel to obtain intermediate product III. S2.4: Add intermediate product III to 5-10 parts by weight of dichloromethane, then stir and mix at 300-500 rpm for 20-30 min. Then add 3-5 parts by weight of trifluoroacetic acid dropwise, and stir and react at 500-600 rpm at room temperature for 4-5 h. After the reaction is complete, add sodium hydroxide to adjust the pH to neutral, wash with water 3-5 times, dry, remove the solvent under reduced pressure, and purify by chromatography on silica gel to obtain a curing agent containing crosslinkable groups.

6. The preparation process of a waterproof and aging-resistant coating for porcelain insulators according to claim 1, characterized in that, S3: The preparation of waterproof and aging-resistant coatings includes the following steps: S3.1: At 400-600 rpm, add 5-15 parts by weight of bisphenol A epoxy resin, 5-15 parts by weight of epoxy acrylate resin, 5-15 parts by weight of butyl acetate and 5-10 parts by weight of cyclohexanone to 80-100 parts by weight of the above aminomethyl silicone resin solution with a solid content of 40-50%, and stir and mix at 400-600 rpm for 20-30 min to obtain a resin mixture; S3.2: Under high-speed dispersion at 800-1200 rpm, add 5-15 parts by weight of PPS resin micro powder with a particle size ≤10μm to the above resin mixture, disperse for 20-30 min, then add 8-10 parts by weight of curing agent mixture, and continue stirring at 600-800 rpm for 30-60 min to obtain mixed slurry. S3.3: Under stirring at 800-1200 rpm, add 3-8 parts by weight of hydrophobic fumed silica, 0.5-2 parts by weight of ultraviolet absorber, 0.1-0.5 parts by weight of leveling agent and 0.1-0.3 parts by weight of defoamer to the mixed slurry, disperse for 20-30 minutes, and then transfer to a sand mill to grind to a fineness ≤20μm to obtain a waterproof and aging-resistant coating.

7. The preparation process of a waterproof and aging-resistant coating for porcelain insulators according to claim 6, characterized in that, The curing agent mixture in step S3.2 consists of a curing agent containing crosslinkable groups, 4,4'-diaminodiphenylmethane, and anhydrous ethanol in a mass ratio of 1:(2-4):(3-5).

8. The preparation process of a waterproof and aging-resistant coating for porcelain insulators according to claim 6, characterized in that, The ultraviolet absorber in step S3.3 is specifically 2-(2H-benzotriazol-2-yl)-4,6-bis(1,1-dimethylpropyl)phenol, the leveling agent is specifically polyether-modified polydimethylsiloxane, and the defoamer is specifically polydimethylsiloxane.

9. A waterproof and aging-resistant coating for porcelain insulators, characterized in that, It is prepared by the preparation process of a waterproof and aging-resistant coating for porcelain insulators as described in any one of claims 1-8.

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