Insulator steel foot coating layer and preparation process thereof

Abstract

The application belongs to the technical field of insulator steel foot coating layer preparation, and particularly relates to an insulator steel foot coating layer and a preparation process thereof. The insulator steel foot coating layer adopts a double-layer composite structure, and from the surface of the steel foot, the coating layer is sequentially provided with a bonding reinforcing layer and a silicone rubber self-repairing microcapsule layer. The thickness of the bonding reinforcing layer is 20-30 microns, and the thickness of the silicone rubber self-repairing microcapsule layer is 120-160 microns. The silicone rubber self-repairing microcapsule layer takes hydroxyl-terminated polydimethylsiloxane as a matrix, and uniformly dispersed therein are self-repairing microcapsules of a core-shell structure. The core material of the self-repairing microcapsule is a composite self-repairing agent, and the shell material is a composite of polyurea and silane-modified nano-silicon dioxide. The insulator steel foot coating layer prepared by the application has high insulation stability, high adhesion, good corrosion resistance, and excellent ultraviolet resistance.

Description

Technical Field

[0001] This invention belongs to the field of insulator steel foot coating preparation technology, specifically relating to an insulator steel foot coating and its preparation process. Background Technology

[0002] Insulator steel feet are the core metal components of transmission line insulators, bearing mechanical load and electrical connection functions. Their long-term service stability directly determines the safety of the power grid. In complex outdoor service environments, insulator steel feet face multiple failure risks: First, due to the difference in dielectric constant at the interface between the steel foot and the insulation component, a high electric field intensity region is formed under operating voltage, which easily induces corona discharge and causes continuous electrochemical corrosion on the surface of the steel foot; Second, the steel foot is exposed to corrosive environments such as moisture, dirt, and industrial atmospheres for a long time, and electrochemical corrosion leads to a reduction in the effective load-bearing cross-sectional area and an increase in interfacial contact resistance, which in severe cases can even cause steel foot breakage and insulator string drop accidents.

[0003] To improve the external insulation performance of insulators, current technologies often employ coating the insulator surface with room temperature vulcanizing silicone rubber anti-pollution flashover coatings to increase the flashover voltage. However, existing technologies still have some limitations: due to factors such as the interfacial chemical inertness between the steel feet and the coating, problems such as insufficient adhesion, peeling, and delamination often occur, leading to premature protection failure. Once existing protective coatings develop microcracks due to external forces or aging, these cracks will gradually expand and become rapid channels for corrosive media, resulting in accelerated localized corrosion that cannot be repaired independently.

[0004] Therefore, it is necessary to develop an insulator steel foot covering layer that is simple to process, has high adhesion, long-lasting corrosion protection, and excellent weather resistance. Summary of the Invention

[0005] Existing insulator steel feet suffer from insufficient protective coverage and poor coating adhesion. To address this issue, this invention provides an insulator steel foot coating layer and its preparation process.

[0006] To achieve the objectives of this invention, the following technical solution is adopted: In a first aspect, the present invention provides an insulator steel foot covering layer, which adopts a double-layer composite structure, comprising an adhesive reinforcement layer and a silicone rubber self-healing microcapsule layer from the inside to the outside of the steel foot surface; the thickness of the adhesive reinforcement layer is 20~30μm, and the thickness of the silicone rubber self-healing microcapsule layer is 120~160μm; the silicone rubber self-healing microcapsule layer uses hydroxyl-terminated polydimethylsiloxane as a matrix, wherein core-shell structured self-healing microcapsules are uniformly dispersed therein; the core material of the self-healing microcapsules is a composite self-healing agent, and the shell material is a composite of polyurea and silane-modified nano-silica.

[0007] By adopting the above technical solution, the inner bonding reinforcement layer forms a strong chemical bond with the steel foot substrate. The outer silicone rubber self-healing microcapsule layer relies on the elastic silicone rubber matrix and, together with the core-shell structured microcapsules, realizes in-situ self-healing of microcracks in the coating, preventing external moisture and salt from penetrating the steel foot substrate along the cracks and causing corrosion. The two layers work together to achieve long-term protection.

[0008] Furthermore, the adhesive reinforcement layer is composed of the following components in parts by weight: The ingredients are: 80-85 parts of silane-modified zinc phosphate, 5-10 parts of γ-aminopropyltriethoxysilane coupling agent, 8-12 parts of anhydrous ethanol, 8-12 parts of bisphenol F epoxy prepolymer, 0.1-0.3 parts of glacial acetic acid, 0.5-1.5 parts of water, and 0.2-0.5 parts of polydimethylsiloxane leveling agent.

[0009] By adopting the above technical solution, silane-modified zinc phosphate is selected as the main filler of the bonding reinforcement layer, which has both rust prevention and interfacial bonding properties. Combined with γ-aminopropyltriethoxysilane coupling agent, bidirectional coupling reinforcement between inorganic filler and metal steel foot and outer silicone rubber layer is achieved, thereby improving interlayer adhesion.

[0010] Furthermore, the silane-modified zinc phosphate is prepared by mixing zinc phosphate, an aqueous ethanol solution, and γ-aminopropyltriethoxysilane coupling agent in a mass ratio of 1:(4~5):(0.1~0.15).

[0011] By adopting the above technical solution, the interfacial wettability between silane-modified zinc phosphate and the steel foot substrate is better under this mass ratio.

[0012] Furthermore, the silicone rubber self-healing microcapsule layer is composed of the following components in parts by weight: 58-65 parts of hydroxyl-terminated polydimethylsiloxane, 12-18 parts of nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane, 2-3 parts of methyltrimethoxysilane, 10-18 parts of self-healing microcapsules, 1.5-2.5 parts of polyvinylpyrrolidone, 0.15-0.25 parts of dibutyltin dilaurate, and 4-7 parts of hindered amine light stabilizer.

[0013] By adopting the above technical solutions, hydroxyl-terminated polydimethylsiloxane is used as the elastic matrix to ensure the coating's flexibility and resistance to high and low temperatures; nano-titanium dioxide is added to modify the matrix, improving the coating's resistance to ultraviolet aging; methyltrimethoxysilane is used as a crosslinking agent, combined with dibutyltin dilaurate catalyst, to achieve rapid curing and molding of the silicone rubber matrix; polyvinylpyrrolidone is used as a dispersant to prevent the aggregation of self-healing microcapsules and ensure their uniform distribution in the matrix; hindered amine light stabilizers further enhance the coating's weather resistance and extend its service life.

[0014] Furthermore, the preparation method of nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane includes the following steps: Hydroxyl-terminated polydimethylsiloxane, silane coupling agent-modified nano-titanium dioxide, and anhydrous ethanol were mixed in a mass ratio of (70~80):(8~12):(15~20), and the mixture was distilled under reduced pressure at 60~70℃, stirred for 1~1.5h, and cooled to obtain nano-titanium dioxide-modified hydroxyl-terminated polydimethylsiloxane.

[0015] By adopting the above technical solution and preparing modified hydroxyl-terminated polydimethylsiloxane by solution blending, the nano-titanium dioxide and siloxane body can be fully combined, thereby improving the UV shielding performance and mechanical strength of the modified hydroxyl-terminated polydimethylsiloxane.

[0016] Furthermore, the preparation method of the self-healing microcapsules includes the following steps: (1) Hydroxyl-terminated polydimethylsiloxane prepolymer, methyltrimethoxysilane, benzotriazole derivative, and γ-aminopropyltriethoxysilane coupling agent are mixed evenly under nitrogen protection, and then dibutyltin dilaurate and isophorone diisocyanate are added and mixed to obtain a composite self-healing agent. (2) Sodium dodecylbenzenesulfonate is mixed with water to obtain an aqueous phase; (3) The composite self-healing agent is slowly added dropwise to the aqueous phase and emulsified at 8000~12000r / min for 15~20min to obtain an emulsion; (4) Slowly add the ethylenediamine aqueous solution to the emulsion, mix evenly, and heat to 40~60℃ for 1~2h; add silane-modified nano silica dispersion and tetraethyl orthosilicate, adjust the pH to 8~9, heat to 50~60℃ for 2~3h, adjust the pH to 7~8, heat to 70~80℃ for 2~3h; cool, filter, wash, and dry to obtain self-repair microcapsules.

[0017] By adopting the above technical solution, the composite self-healing agent uses hydroxyl-terminated polydimethylsiloxane prepolymer combined with methyltrimethoxysilane crosslinking components to ensure good compatibility between the repair agent released after microcapsule rupture and the substrate coating, resulting in a defect-free interface after repair. Benzotriazole derivatives have corrosion-inhibiting effects, and γ-aminopropyltriethoxysilane coupling agents enhance the bonding force between the core and shell materials. Microcapsules are prepared via interfacial polymerization, where ethylenediamine reacts with isophorone diisocyanate to generate a polyurea wall material. Silane-modified nano-silica and tetraethyl orthosilicate are introduced to form a polyurea-silica composite shell. This composite shell combines the toughness of polyurea with the rigidity of silica, resulting in moderate capsule wall strength. This ensures that the microcapsules do not rupture prematurely during processing and that the core material is released promptly when cracks occur. Simultaneously, the reaction temperature and pH value are controlled to ensure uniform microcapsule particle size and high encapsulation efficiency.

[0018] Further, in step (1), the mass ratio of the hydroxyl-terminated polydimethylsiloxane prepolymer, methyltrimethoxysilane, benzotriazole derivative, γ-aminopropyltriethoxysilane coupling agent, dibutyltin dilaurate and isophorone diisocyanate is (45~55):(27~33):(3~6):(2~4):(0.1~0.3):(16~20).

[0019] By adopting the above technical solution, under this ratio, the core material can be guaranteed to have cross-linking repair activity, ensuring that the repair agent can quickly flow and fill the cracks after the microcapsules rupture.

[0020] Further, in step (2), the mass ratio of the composite self-healing agent, sodium dodecylbenzenesulfonate, water, ethylenediamine aqueous solution, silane-modified nano silica dispersion, and tetraethyl orthosilicate is (100~120):(1~2):(200~250):(15~18):(20~30):(15~25); and the mass fraction of the ethylenediamine aqueous solution is 20%.

[0021] By adopting the above technical solution, sodium dodecylbenzenesulfonate is used as an emulsifier, and a moderate amount is used to form a stable emulsion; the ratio of ethylenediamine to isophorone diisocyanate is balanced, the polyurea wall material has a moderate degree of crosslinking, strong toughness and is not easy to crack; the ratio of silane-modified nano silica dispersion to tetraethyl orthosilicate is reasonable, forming a uniform silica composite layer on the surface of polyurea wall material, further enhancing the barrier properties and mechanical properties of the shell material.

[0022] Furthermore, in step (2), the preparation method of the silane-modified nano-silica dispersion includes the following steps: Nano-silica, anhydrous ethanol, water and γ-aminopropyltriethoxysilane coupling agent are mixed in a mass ratio of (15~20):(60~70):(10~15):(1.2~2), the pH is adjusted to 4~5, and the mixture is heated to 50~60℃ and reacted for 3~4 hours to obtain a silane-modified nano-silica dispersion.

[0023] By adopting the above technical solution, silane modification of nano-silica is performed to improve its dispersibility with organic shell materials, avoid nanoparticle aggregation, and enhance the overall stability of microcapsules.

[0024] Secondly, the present invention provides a process for preparing an insulator steel foot covering layer, comprising the following steps: S1: First, mix anhydrous ethanol, water, and glacial acetic acid evenly, add γ-aminopropyltriethoxysilane coupling agent, and stir at room temperature for 15 minutes; add silane-modified zinc phosphate, low molecular weight bisphenol F epoxy prepolymer, and polydimethylsiloxane leveling agent, ultrasonically disperse for 15-20 minutes, coat it on the surface of the insulator steel foot, and cure at 125-135℃ for 30-40 minutes to obtain the bonding reinforcement layer; S2: Hydroxyl-terminated polydimethylsiloxane, nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane, methyltrimethoxysilane, and polyvinylpyrrolidone are mixed and stirred at 300~500 r / min for 15~20 min. Self-healing microcapsules are added and stirring is continued for 20~30 min. Dibutyltin dilaurate and hindered amine light stabilizer are added and stirred for 10~15 min. The mixture is coated onto the surface of the bonding reinforcement layer in multiple coats at a spraying pressure of 0.3~0.5 MPa and a spraying distance of 20~30 cm. The mixture is cured at 80~100℃ for 1~1.5 h to form a silicone rubber self-healing microcapsule layer, which is the insulator steel foot coating layer.

[0025] By adopting the above technical solution, the preparation process is simple and easy to operate, and is suitable for industrial mass production. First, the bonding reinforcement layer is prepared and cured to ensure that the inner layer is firmly bonded to the steel foot. Then, the outer silicone rubber layer is prepared and sprayed in multiple layers to ensure that the coating thickness is uniform. After complete curing, the coating performance is stable. The double-layer structure works together to achieve multiple protective effects such as high adhesion, salt spray resistance, and UV resistance.

[0026] In summary, the beneficial effects of this invention are: (1) The present invention adopts a double-layer composite structure of inner bonding reinforcement layer and outer silicone rubber self-healing layer, which is tightly bonded, without delamination or pinholes; the bonding reinforcement layer forms a strong bond with the steel foot through chemical bonding, with high interface bonding strength, which solves the problem of poor adhesion between traditional silicone rubber coating and metal substrate and easy peeling and detachment. (2) The self-healing microcapsules are uniformly dispersed in the silicone rubber self-healing layer matrix of the present invention. When the coating is subjected to external force and microcracks are generated, the microcapsules are compressed and rupture to release the self-healing agent, which can quickly fill the cracks and cross-link and solidify in situ, realize the autonomous closure of microcracks, block the intrusion of external corrosive media such as moisture and salt, and extend the outdoor service life of the insulator steel foot. (3) This invention modifies the terminal hydroxyl polydimethylsiloxane by nano-titanium dioxide and combines it with hindered amine light stabilizers to improve the coating’s resistance to ultraviolet aging and yellowing; combined with the cross-linking curing system composed of methyltrimethoxysilane and dibutyltin dilaurate, the coating has both excellent flexibility and mechanical strength. (4) The preparation process of this invention is simple and controllable, and the production safety is high. It can be adapted to the industrial mass production needs of insulator steel feet. Attached Figure Description

[0027] Figure 1 SEM image of the self-healing microcapsules prepared according to the present invention. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to specific embodiments.

[0029] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples and comparative examples are commercially available. Specifically, the hindered amine light stabilizer used in the following examples and comparative examples is light stabilizer 944; the benzotriazole derivative used is methylbenzotriazole.

[0030] Example 1 This embodiment of an insulator steel foot covering layer adopts a double-layer composite structure, with an adhesive reinforcement layer and a silicone rubber self-healing microcapsule layer sequentially from the inside to the outside of the steel foot surface; The adhesive reinforcement layer consists of the following components in parts by weight: 82 parts of silane-modified zinc phosphate, 8 parts of γ-aminopropyltriethoxysilane coupling agent, 8 parts of anhydrous ethanol, 10 parts of bisphenol F epoxy prepolymer, 0.2 parts of glacial acetic acid, 1.5 parts of water, and 0.3 parts of polydimethylsiloxane leveling agent; The self-healing microcapsule layer is composed of the following components in parts by weight: 62 parts of hydroxyl-terminated polydimethylsiloxane, 15 parts of nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane, 3 parts of methyltrimethoxysilane, 18 parts of self-healing microcapsules, 2 parts of polyvinylpyrrolidone, 0.2 parts of dibutyltin dilaurate, and 5 parts of hindered amine light stabilizer.

[0031] The specific steps of the method for preparing the insulator steel foot coating layer in this embodiment are as follows: 1. Preparation of silane-modified zinc phosphate 100g of zinc phosphate was mixed with 450g of anhydrous ethanol aqueous solution (anhydrous ethanol:water = 9:1, m / m), stirred and dispersed for 25min, heated to 60℃, and 12g of γ-aminopropyltriethoxysilane coupling agent was added dropwise to adjust the pH to 6. The reaction was allowed to proceed for 4h. After the reaction was completed, the mixture was filtered, washed three times with anhydrous ethanol, transferred to a vacuum drying oven and dried at 80℃ for 8h. The mixture was then pulverized and passed through a 200-300 mesh sieve to obtain silane-modified zinc phosphate.

[0032] 2. Preparation of nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane 75g of hydroxyl-terminated polydimethylsiloxane, 10g of silane coupling agent-modified nano-titanium dioxide, and 20g of anhydrous ethanol were mixed and stirred for 30min, then distilled under reduced pressure at 70℃ for 1h, and cooled to room temperature to obtain nano-titanium dioxide-modified hydroxyl-terminated polydimethylsiloxane.

[0033] 3. Preparation of silane-modified nano-silica dispersion Mix 18g of nano-silica, 65g of anhydrous ethanol, 12g of deionized water, and 1.6g of γ-aminopropyltriethoxysilane coupling agent, sonicate for 30min, adjust the pH to 5, heat to 55℃ and react for 3h, cool to room temperature to obtain silane-modified nano-silica dispersion.

[0034] 4. Preparation of self-healing microcapsules (1) Under nitrogen protection, 50g of hydroxyl-terminated polydimethylsiloxane prepolymer, 30g of methyltrimethoxysilane, 5g of benzotriazole derivative, and 3g of γ-aminopropyltriethoxysilane coupling agent were mixed and stirred for 30min. First, 0.2g of dibutyltin dilaurate was added and stirred for 5min. Then, 18g of isophorone diisocyanate was added and stirred for another 10min to obtain a composite self-healing agent. (2) Mix 0.6g sodium dodecylbenzenesulfonate with 120g water and stir for 25min to obtain an aqueous phase; (3) Slowly add 58g of composite self-healing agent to the aqueous phase and emulsify at 10000r / min for 20min to obtain an emulsion; (4) 8g of 20% ethylenediamine aqueous solution was slowly added dropwise to the emulsion, mixed evenly, and heated to 50℃ for 2h. 13g of silane-modified nano silica dispersion and 10g of tetraethyl orthosilicate were added, the pH of the system was adjusted to 9, and the temperature was raised to 50℃ for 3h. The pH was adjusted to 7, and the temperature was raised to 75℃ for 3h. The mixture was cooled to room temperature, filtered, washed 5 times with deionized water, and transferred to a vacuum drying oven to dry at 60℃ for 12h to obtain self-repairing microcapsules.

[0035] SEM images of the self-healing microcapsules are shown below. Figure 1 As can be seen from the figure, the self-healing microcapsules are spherical with clear particle outlines, good dispersibility, relatively uniform particle size distribution, and no obvious agglomeration or adhesion.

[0036] 5. Preparation of the insulator steel foot coating layer First, the steel feet of the insulator are pretreated: the steel feet of the insulator are ultrasonically degreased with acetone for 20 minutes, roughened with 300-grit sandpaper, pickled with 8% dilute hydrochloric acid for 12 minutes, rinsed with deionized water until neutral, and dried in an oven at 80℃ for 2 hours. S1: First, mix anhydrous ethanol, water, and glacial acetic acid and stir for 15 min. Then, add γ-aminopropyltriethoxysilane coupling agent and stir at room temperature for 15 min. Add silane-modified zinc phosphate, low molecular weight bisphenol F epoxy prepolymer, and polydimethylsiloxane leveling agent. Disperse ultrasonically for 20 min, coat it on the surface of the insulator steel foot, level it at room temperature for 10 min, and cure it at 130℃ for 35 min to obtain a 25 μm thick bonding reinforcement layer. S2: Hydroxyl-terminated polydimethylsiloxane, nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane, methyltrimethoxysilane and polyvinylpyrrolidone were mixed and stirred at 450 r / min for 18 min. Self-healing microcapsules were added and stirring was continued for 30 min. Dibutyltin dilaurate and hindered amine light stabilizer were added and stirred for 10 min. The adhesive reinforcement layer was coated in three layers by spraying at a pressure of 0.4 MPa and a distance of 25 cm. After each layer of spraying, the coating was leveled at room temperature for 12 min. After all three layers of spraying were completed, the coating was cured at 100℃ for 1.2 h to obtain a silicone rubber self-healing microcapsule layer with a thickness of 142 μm. Finally, a complete insulator steel foot coating layer with a total thickness of 167 μm was obtained.

[0037] Example 2 The difference from Example 1 is as follows: The composition of the bonding reinforcement layer was adjusted as follows: 80 parts of silane-modified zinc phosphate, 5 parts of γ-aminopropyltriethoxysilane coupling agent, 8 parts of anhydrous ethanol, 9 parts of bisphenol F epoxy prepolymer, 0.1 parts of glacial acetic acid, 1 part of deionized water, and 0.5 parts of polydimethylsiloxane leveling agent. The composition of the silicone rubber self-healing microcapsule layer was adjusted as follows: 58 parts of hydroxyl-terminated polydimethylsiloxane, 14 parts of nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane, 2 parts of methyltrimethoxysilane, 10 parts of self-healing microcapsules, 1.5 parts of polyvinylpyrrolidone, 0.15 parts of dibutyltin dilaurate, and 4 parts of hindered amine light stabilizer. The remaining preparation methods and process parameters are the same as in Example 1; the thickness of the bonding reinforcement layer is 23 μm, the thickness of the silicone rubber self-healing microcapsule layer is 145 μm, and the total thickness of the coating layer is 168 μm.

[0038] Example 3 The difference from Example 1 is as follows: The composition of the bonding reinforcement layer was adjusted as follows: 85 parts of silane-modified zinc phosphate, 6 parts of γ-aminopropyltriethoxysilane coupling agent, 9 parts of anhydrous ethanol, 8 parts of bisphenol F epoxy prepolymer, 0.3 parts of glacial acetic acid, 1 part of deionized water, and 0.4 parts of polydimethylsiloxane leveling agent. The composition of the silicone rubber self-healing microcapsule layer was adjusted as follows: 60 parts of hydroxyl-terminated polydimethylsiloxane, 18 parts of nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane, 3 parts of methyltrimethoxysilane, 16 parts of self-healing microcapsules, 2.5 parts of polyvinylpyrrolidone, 0.22 parts of dibutyltin dilaurate, and 7 parts of hindered amine light stabilizer. The remaining preparation methods and process parameters are the same as in Example 1; the thickness of the bonding reinforcement layer is 20 μm, the thickness of the silicone rubber self-healing microcapsule layer is 150 μm, and the total thickness of the coating layer is 170 μm.

[0039] Example 4 The difference from Example 1 is as follows: The composition of the bonding reinforcement layer was adjusted as follows: 84 parts of silane-modified zinc phosphate, 10 parts of γ-aminopropyltriethoxysilane coupling agent, 11 parts of anhydrous ethanol, 12 parts of bisphenol F epoxy prepolymer, 0.3 parts of glacial acetic acid, 1.5 parts of deionized water, and 0.5 parts of polydimethylsiloxane leveling agent. The composition of the self-healing microcapsule layer of silicone rubber was adjusted as follows: 65 parts of hydroxyl-terminated polydimethylsiloxane, 13 parts of nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane, 2.5 parts of methyltrimethoxysilane, 15 parts of self-healing microcapsules, 2.1 parts of polyvinylpyrrolidone, 0.2 parts of dibutyltin dilaurate, and 6 parts of hindered amine light stabilizer. The remaining preparation methods and process parameters are the same as in Example 1; the thickness of the bonding reinforcement layer is 22 μm, the thickness of the silicone rubber self-healing microcapsule layer is 130 μm, and the total thickness of the coating layer is 152 μm.

[0040] Example 5 The difference from Example 1 is as follows: In the preparation of self-healing microcapsules, the mass ratio of hydroxyl-terminated polydimethylsiloxane prepolymer, methyltrimethoxysilane, benzotriazole derivative and γ-aminopropyltriethoxysilane coupling agent was adjusted to 48:28:5:3.2. The outer silicone rubber layer is cured at a temperature of 85℃ for 1.5 hours. The remaining preparation methods and process parameters are the same as in Example 1; the thickness of the bonding reinforcement layer is 22 μm, the thickness of the silicone rubber self-healing microcapsule layer is 132 μm, and the total thickness of the coating layer is 154 μm.

[0041] Example 6 The difference from Example 1 is as follows: In the preparation of silane-modified nano silica dispersion, the mass ratio of nano silica, anhydrous ethanol, deionized water and γ-aminopropyltriethoxysilane coupling agent was adjusted to 16:68:14:1.8, the reaction temperature was adjusted to 60℃, and the reaction time was 3.5h. In the preparation of self-healing microcapsules, the mass ratio of hydroxyl-terminated polydimethylsiloxane prepolymer, methyltrimethoxysilane, benzotriazole derivative and γ-aminopropyltriethoxysilane coupling agent was adjusted to 53:32:6:3.2. The remaining preparation methods and process parameters are the same as in Example 1; the thickness of the bonding reinforcement layer is 28 μm, the thickness of the silicone rubber self-healing microcapsule layer is 151 μm, and the total thickness of the coating layer is 179 μm.

[0042] Example 7 The difference from Example 1 is as follows: In the preparation of silane-modified zinc phosphate, the mass ratio of zinc phosphate, aqueous ethanol solution and γ-aminopropyltriethoxysilane coupling agent was adjusted to 1:4:0.11, the reaction temperature was 55℃, and the reaction time was 4h. The composition of the bonding reinforcement layer was adjusted as follows: 81 parts of silane-modified zinc phosphate, 6 parts of γ-aminopropyltriethoxysilane coupling agent, 10 parts of anhydrous ethanol, 10 parts of bisphenol F epoxy prepolymer, 0.2 parts of glacial acetic acid, 1.2 parts of deionized water, and 0.4 parts of polydimethylsiloxane leveling agent; the curing temperature was 125℃, and the curing time was 40 min. The remaining preparation methods and process parameters are the same as in Example 1; the thickness of the bonding reinforcement layer is 20 μm, the thickness of the silicone rubber self-healing microcapsule layer is 138 μm, and the total thickness of the coating layer is 158 μm.

[0043] Example 8 The difference from Example 1 is as follows: In the preparation of silane-modified zinc phosphate, the mass ratio of zinc phosphate, aqueous ethanol solution and γ-aminopropyltriethoxysilane coupling agent was adjusted to 1:5:0.14, the reaction temperature was 65℃, and the reaction time was 3h. In the preparation of self-healing microcapsules, the mass ratio of composite self-healing agent, sodium dodecylbenzenesulfonate, water, 20% ethylenediamine aqueous solution, isophorone diisocyanate, silane-modified nano silica dispersion, and tetraethyl orthosilicate is 120:2:220:15:20:20. The remaining preparation methods and process parameters are the same as in Example 1; the thickness of the bonding reinforcement layer is 24 μm, the thickness of the silicone rubber self-healing microcapsule layer is 155 μm, and the total thickness of the coating layer is 179 μm.

[0044] Example 9 The difference from Example 1 is as follows: In the preparation of nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane, the mass ratio of hydroxyl-terminated polydimethylsiloxane, silane coupling agent modified nano-titanium dioxide, and anhydrous ethanol is 78:12:17.

[0045] The remaining preparation methods and process parameters are the same as in Example 1; the thickness of the bonding reinforcement layer is 20 μm, the thickness of the silicone rubber self-healing microcapsule layer is 156 μm, and the total thickness of the coating layer is 176 μm.

[0046] Example 10 The difference from Example 1 is as follows: In the preparation of nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane, the mass ratio of hydroxyl-terminated polydimethylsiloxane, silane coupling agent modified nano-titanium dioxide and anhydrous ethanol is 72:9:15. In the preparation of the self-healing silicone rubber microcapsule layer, the spraying pressure was 0.5 MPa, the spraying distance was 27 cm, the curing temperature was 85 ℃, and the curing time was 1 h.

[0047] The remaining preparation methods and process parameters are the same as in Example 1; the thickness of the bonding reinforcement layer is 27 μm, the thickness of the silicone rubber self-healing microcapsule layer is 140 μm, and the total thickness of the coating layer is 167 μm.

[0048] Comparative Example 1 The difference from Example 1 is that: This comparative example did not include an adhesive reinforcement layer; the silicone rubber self-healing microcapsule layer was directly coated onto the pretreated steel foot surface. The remaining preparation methods and process parameters were the same as in Example 1.

[0049] Comparative Example 2 The difference from Example 1 is that: No self-healing microcapsules were added to the silicone rubber self-healing microcapsule layer; the rest of the preparation methods and process parameters were the same as in Example 1.

[0050] Comparative Example 3 The self-healing silicone rubber microcapsule layer did not contain nano-titanium dioxide-modified hydroxyl-terminated polydimethylsiloxane; instead, an equal amount of ordinary hydroxyl-terminated polydimethylsiloxane was used as a substitute. The remaining preparation methods and process parameters were consistent with those in Example 1.

[0051] Related performance tests The relevant performance tests were conducted on Examples 1-10 and Comparative Examples 1-3, and the test results are shown in Table 1.

[0052] Table 1 Test Results

[0053] As shown in Table 1, Examples 1-10 showed good adhesion, with the double-layer coatings bonded tightly and without peeling. In Comparative Example 1, the adhesion was reduced due to the lack of a bonding reinforcement layer, and the coating was prone to peeling and delamination, resulting in failure of interface protection.

[0054] Examples 1-10 show a stable self-healing rate of over 90% for microcracks. After the microcapsules rupture, the repair agent can quickly flow and fill the cracks in situ, resulting in complete crack closure. Comparative Example 2, without the addition of self-healing microcapsules, has no self-healing ability, and long-term exposure of the cracks can easily lead to corrosion. Comparative Examples 1 and 3 show reduced self-healing efficiency due to interface defects.

[0055] Examples 1-10 showed no rust or blistering after 1000 hours of salt spray testing, and their performance retention rate after UV aging exceeded 90%, demonstrating excellent weather resistance and corrosion protection. Comparative Example 2, lacking self-healing function, experienced localized corrosion due to the gradual expansion of minor cracks. Comparative Example 3, without nano-titanium dioxide modification, exhibited decreased UV resistance and its coating became brittle.

[0056] Examples 1-10 show that the breakdown field strength meets the high-voltage insulator protection standards, and the insulation stability is strong.

[0057] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A steel foot covering layer for an insulator, characterized in that, The device employs a dual-layer composite structure, consisting of an adhesive reinforcement layer and a silicone rubber self-healing microcapsule layer, arranged sequentially from the inside to the outside of the steel foot surface. The adhesive reinforcement layer has a thickness of 20-30 μm, and the silicone rubber self-healing microcapsule layer has a thickness of 120-160 μm. The silicone rubber self-healing microcapsule layer uses hydroxyl-terminated polydimethylsiloxane as a matrix, in which core-shell structured self-healing microcapsules are uniformly dispersed. The core material of the self-healing microcapsules is a composite self-healing agent, and the shell material is a composite of polyurea and silane-modified nano-silica.

2. The insulator steel foot covering layer according to claim 1, characterized in that, The adhesive reinforcement layer is composed of the following components in parts by weight: The ingredients are: 80-85 parts of silane-modified zinc phosphate, 5-10 parts of γ-aminopropyltriethoxysilane coupling agent, 8-12 parts of anhydrous ethanol, 8-12 parts of bisphenol F epoxy prepolymer, 0.1-0.3 parts of glacial acetic acid, 0.5-1.5 parts of water, and 0.2-0.5 parts of polydimethylsiloxane leveling agent.

3. The insulator steel foot covering layer according to claim 2, characterized in that, The silane-modified zinc phosphate is prepared by mixing zinc phosphate, an aqueous ethanol solution, and γ-aminopropyltriethoxysilane coupling agent in a mass ratio of 1:(4~5):(0.1~0.15).

4. The insulator steel foot covering layer according to claim 1, characterized in that, The silicone rubber self-healing microcapsule layer is composed of the following components in parts by weight: 58-65 parts of hydroxyl-terminated polydimethylsiloxane, 12-18 parts of nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane, 2-3 parts of methyltrimethoxysilane, 10-18 parts of self-healing microcapsules, 1.5-2.5 parts of polyvinylpyrrolidone, 0.15-0.25 parts of dibutyltin dilaurate, and 4-7 parts of hindered amine light stabilizer.

5. The insulator steel foot covering layer according to claim 4, characterized in that, The preparation method of nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane includes the following steps: Hydroxyl-terminated polydimethylsiloxane, silane coupling agent-modified nano-titanium dioxide, and anhydrous ethanol were mixed in a mass ratio of (70~80):(8~12):(15~20), and the mixture was distilled under reduced pressure at 60~70℃, stirred for 1~1.5h, and cooled to obtain nano-titanium dioxide-modified hydroxyl-terminated polydimethylsiloxane.

6. The insulator steel foot covering layer according to claim 4, characterized in that, The preparation method of self-healing microcapsules includes the following steps: (1) Hydroxyl-terminated polydimethylsiloxane prepolymer, methyltrimethoxysilane, benzotriazole derivative, and γ-aminopropyltriethoxysilane coupling agent are mixed evenly under nitrogen protection, and then dibutyltin dilaurate and isophorone diisocyanate are added and mixed to obtain a composite self-healing agent. (2) Sodium dodecylbenzenesulfonate is mixed with water to obtain an aqueous phase; (3) The composite self-healing agent is slowly added dropwise to the aqueous phase and emulsified at 8000~12000r / min for 15~20min to obtain an emulsion; (4) Slowly add the ethylenediamine aqueous solution to the emulsion, mix evenly, and heat to 40~60℃ for 1~2h; add silane-modified nano silica dispersion and tetraethyl orthosilicate, adjust the pH to 8~9, heat to 50~60℃ for 2~3h, adjust the pH to 7~8, and heat to 70~80℃ for 2~3h. Cooling, filtering, washing, drying, and the resulting repair microcapsules.

7. The insulator steel foot covering layer according to claim 6, characterized in that, In step (1), the mass ratio of hydroxyl-terminated polydimethylsiloxane prepolymer, methyltrimethoxysilane, benzotriazole derivative, γ-aminopropyltriethoxysilane coupling agent, dibutyltin dilaurate and isophorone diisocyanate is (45~55):(27~33):(3~6):(2~4):(0.1~0.3):(16~20).

8. The insulator steel foot covering layer according to claim 6, characterized in that, The mass ratio of the composite self-healing agent, sodium dodecylbenzenesulfonate, water, ethylenediamine aqueous solution, silane-modified nano-silica dispersion, and tetraethyl orthosilicate is (100~120):(1~2):(200~250):(15~18):(20~30):(15~25); the mass fraction of the ethylenediamine aqueous solution is 20%.

9. The insulator steel foot covering layer according to claim 6, characterized in that, In step (2), the preparation method of the silane-modified nano-silica dispersion includes the following steps: Nano-silica, anhydrous ethanol, water and γ-aminopropyltriethoxysilane coupling agent are mixed in a mass ratio of (15~20):(60~70):(10~15):(1.2~2), the pH is adjusted to 4~5, and the mixture is heated to 50~60℃ and reacted for 3~4 hours to obtain a silane-modified nano-silica dispersion.

10. The preparation process of the insulator steel foot coating layer according to any one of claims 1-9, characterized in that, Includes the following steps: S1: First, mix anhydrous ethanol, water, and glacial acetic acid evenly, add γ-aminopropyltriethoxysilane coupling agent, and stir at room temperature for 15 minutes; add silane-modified zinc phosphate, low molecular weight bisphenol F epoxy prepolymer, and polydimethylsiloxane leveling agent, ultrasonically disperse for 15-20 minutes, coat it on the surface of the insulator steel foot, and cure at 125-135℃ for 30-40 minutes to obtain the bonding reinforcement layer; S2: Hydroxyl-terminated polydimethylsiloxane, nano-titanium dioxide modified hydroxyl-terminated polydimethylsiloxane, methyltrimethoxysilane, and polyvinylpyrrolidone are mixed and stirred at 300~500 r / min for 15~20 min. Self-healing microcapsules are added and stirring is continued for 20~30 min. Dibutyltin dilaurate and hindered amine light stabilizer are added and stirred for 10~15 min. The mixture is coated onto the surface of the bonding reinforcement layer in multiple coats at a spraying pressure of 0.3~0.5 MPa and a spraying distance of 20~30 cm. The mixture is cured at 80~100℃ for 1~1.5 h to form a silicone rubber self-healing microcapsule layer, which is the insulator steel foot coating layer.

Images