Preparation method of voltage breakdown-resistant anti-corrosion functional filler

Abstract

The invention discloses a preparation method of a voltage-breakdown-resistant anticorrosive functional filler, and belongs to the field of preparation of coating fillers. The boron nitride nanosheet is subjected to surface amination modification, then zinc molybdate grows in situ, finally, ester compound hydrolytic condensation is utilized for surface treatment, and the composite filler with multiple functions of physical shielding, efficient insulation and active corrosion inhibition is successfully constructed. According to the method, not only can the dispersity and interface bonding force of the filler in the resin be effectively improved and the defects of the coating be reduced, but also the insulation barrier characteristic of boron nitride and the electrochemical anti-corrosion effect of zinc molybdate can be synergistically exerted, so that the long-term corrosion resistance and high-voltage electric breakdown resistance of the coating in a severe environment can be remarkably enhanced.

Description

Technical Field

[0001] This invention belongs to the field of coating filler preparation, and specifically relates to a method for preparing a filler with voltage breakdown resistance and corrosion protection. Background Technology

[0002] With the increasing application of industrial equipment in extreme environments, the functional requirements of metal anti-corrosion coatings are shifting from single-function protection to multi-functional integration. Coatings that combine corrosion resistance and voltage breakdown resistance have become a research hotspot, especially in fields such as power equipment and electronic information. These coatings can simultaneously resist chemical corrosion and electrical breakdown risks, significantly extending the service life of the metal substrate. This trend is driven by the limitations of traditional coatings: simple anti-corrosion coatings are prone to insulation failure under high-voltage electric fields due to dielectric penetration, while ordinary insulating materials are insufficient to withstand the erosion of corrosive media. Current research has shown that adding functional fillers is a convenient and effective strategy to endow coatings with multi-functionality. Through the unique physical barrier effect and high resistivity of two-dimensional nanomaterials (such as boron nitride, alumina, and zirconium phosphate), the penetration path of corrosive media can be extended simultaneously while inhibiting electrical breakdown. This "one material, multiple uses" strategy significantly reduces the complexity of the coating system, providing a new approach to multi-functional integration.

[0003] However, from the perspective of practical application, there are still some problems that need to be solved, mainly in the following aspects: (1) Insufficient dispersion and interfacial bonding of inorganic nanosheet fillers. Two-dimensional nanomaterials are prone to agglomeration in the resin matrix due to their large specific surface area and high surface energy, resulting in poor coating uniformity. For example, boron nitride nanosheets in epoxy resin will form a "stacked structure" due to van der Waals forces if they are not surface modified. This not only fails to exert a physical barrier effect, but also forms micropore defects inside the coating, becoming a channel for the penetration of corrosive media. In addition, the interfacial bonding between nanofillers and the resin matrix is ​​weak, and they are prone to separation under mechanical stress or thermal cycling, further reducing the coating performance. (2) The anti-corrosion mechanism is simple and difficult to meet the requirements of long service life (such as the invention patents with publication numbers CN120041049A and CN115232538A). Existing research focuses on physical shielding anti-corrosion mechanisms, that is, extending the penetration path of corrosive media through nanosheets, but this mechanism may fail during long-term service. For example, in high-temperature and high-humidity environments, microcracks within the coating can accelerate the penetration of corrosive media, leading to localized corrosion of the substrate. While electrochemical corrosion protection mechanisms (such as sacrificial anode protection and corrosion inhibitor release) can actively inhibit corrosion, they require the introduction of functional fillers such as zinc powder and molybdates, which increases the complexity of the coating system. More importantly, the introduction of multifunctional fillers may cause compatibility issues; for example, the synergistic effect of zinc powder and nanosheets can reduce the insulation performance of the coating, necessitating the optimization of the interactions between fillers through interface engineering. Summary of the Invention

[0004] This invention aims to overcome the problems of single function, insufficient long-term protection, and poor compatibility with resin matrices in existing anti-corrosion coatings, and provides a method for preparing a voltage-breakdown resistant anti-corrosion filler. The method involves surface-modifying boron nitride nanosheets with amino groups, followed by in-situ growth of zinc molybdate, and finally surface treatment using ester compounds via hydrolysis and condensation. This successfully constructs a composite filler with multiple functions, including physical shielding, high-efficiency insulation, and active corrosion inhibition. This method not only effectively improves the filler's dispersibility and interfacial bonding in the resin and reduces coating defects, but also synergistically leverages the insulating barrier properties of boron nitride and the electrochemical anti-corrosion effect of zinc molybdate, thereby significantly enhancing the coating's long-term corrosion resistance and high-voltage breakdown resistance under harsh environments.

[0005] To solve the above-mentioned technical problems, the solution of the present invention is: This invention provides a method for preparing a voltage-breakdown resistant and corrosion-resistant filler, comprising the following steps: (1) Boron nitride sheets were peeled and surface modified to obtain a modified boron nitride nanosheet dispersion with amino groups grafted onto the surface; (2) The modified boron nitride nanosheet dispersion obtained in step (1) and the mixture of zinc salt and molybdate are mixed and reacted to allow zinc molybdate to grow in situ on the surface of the modified boron nitride nanosheets, thereby obtaining a zinc molybdate modified boron nitride nanosheet dispersion. (3) An ester compound was added to the zinc molybdate modified boron nitride nanosheet dispersion obtained in step (2) and reacted. After post-treatment, the voltage breakdown and corrosion-resistant filler was obtained.

[0006] Further, step (1) specifically involves: adding boron nitride sheets to a solvent and ultrasonically oscillating them, followed by a hydrothermal reaction; washing the reaction product and dispersing it in an alcoholic water solvent, adjusting the pH to acidic, and adding an amino-containing silane coupling agent to carry out a reflux reaction; washing the reaction product and dispersing it in a mixed solvent to obtain the modified boron nitride nanosheet dispersion.

[0007] As a preferred embodiment, in step (1), the solvent is at least one of N-methylpyrrolidone, N,N-dimethylformamide, and dimethyl sulfoxide; The mixed solvent is anhydrous ethanol and ethylene glycol in a mass ratio of 1:1; The amino-containing silane coupling agent is at least one of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane. The mass ratio of the boron nitride sheet to the amino-containing silane coupling agent is 1:0.05~0.1.

[0008] To ensure uniform mixing, adjust the pH to 4.0-5.0 using at least one of glacial acetic acid, oxalic acid, or formic acid. This can be achieved by adding an amino-containing silane coupling agent at a stirring speed of 300 rpm at a rate of 3 ml / min.

[0009] Furthermore, in step (1), the frequency of the ultrasonic oscillation is 80~200kHz, and the duration is 2~5h; The hydrothermal reaction is carried out at a temperature of 160~200℃ for 5~12 hours. The condensation reflux reaction is carried out at a temperature of 60-80°C for 5-10 hours.

[0010] Further, in step (2), the zinc salt is at least one of zinc nitrate, zinc acetate, and zinc citrate; The molybdate is at least one of sodium molybdate and potassium molybdate; In the mixture of zinc salt and molybdate, the molar ratio of zinc atoms to molybdenum atoms is 1:1; The mass ratio of the modified boron nitride nanosheet dispersion and the mixture of zinc salt and molybdate is 100:0.1~0.3.

[0011] As a preferred embodiment, in step (2), the reaction conditions are: reacting at 140~180℃ for 6~24h; after the reaction, the product is washed and dispersed in a mixed solvent composed of organic solvent and deionized water to obtain the zinc molybdate modified boron nitride nanosheet dispersion, wherein the mass ratio of organic solvent to deionized water is 10~100:1.

[0012] Specifically, in step (2), the organic solvent is at least one of anhydrous ethanol, propylene glycol methyl ether, and N,N-dimethylformamide.

[0013] In steps (1) and (2), after the reaction is carried out, the reaction solution is filtered and the precipitate is collected. The precipitate is washed three times alternately with deionized water and anhydrous ethanol.

[0014] Further, in step (3), before adding the ester compound, the pH value of the system is adjusted to 3.0~5.0 using a pH adjuster; the pH adjuster is at least one of glacial acetic acid, oxalic acid, and formic acid.

[0015] As a preferred embodiment, in step (3), the ester compound is at least one of tetraethyl orthosilicate, tetrabutyl titanate, and methyl orthosilicate; When the ester compound is added in the form of a 5% (w / w) ethanol solution, and the solid content of the zinc molybdate-modified boron nitride nanosheet dispersion is 10%, the mass ratio of the ester compound added to the zinc molybdate-modified boron nitride nanosheet dispersion is 1:1 to 5.

[0016] Further, in step (3), the post-processing includes: filtering the reaction product, and concentrating the resulting filtrate to obtain the voltage breakdown and corrosion-resistant filler with a solid content of 30%.

[0017] Description of the principle of this invention: This invention utilizes a polar aprotic solvent to penetrate into the interlayer space of lamellar boron nitride under liquid-phase heating conditions. By utilizing the interaction between polar molecules and the BN bonds between boron nitride layers, the interlayer binding energy is weakened, thereby promoting the exfoliation of boron nitride sheets to obtain boron nitride nanosheets. Furthermore, by continuously modifying and composite-modifying the surface of boron nitride nanosheets in a liquid medium, the aggregation of boron nitride nanosheets during the drying process is avoided.

[0018] A silane coupling agent containing amino groups was selected. By controlling the condensation of the alcohol hydroxyl groups formed by the hydrolysis of the silane coupling agent with the hydroxyl groups on the surface of boron nitride nanosheets, the amino group was introduced into the surface of boron nitride nanosheets, providing sites for the subsequent growth of zinc molybdate on the surface of boron nitride nanosheets.

[0019] By utilizing the hydrolysis and condensation of ester compounds on the surface of boron nitride, abundant hydroxyl groups are provided on its surface. When this filler is added to resin to form a coating, the active groups in the resin react with the hydroxyl groups to form chemical bonds during the curing of the coating, thereby making the filler and resin tightly bonded.

[0020] Compared with the prior art, the beneficial effects of the present invention are: 1. The functional filler prepared by this invention achieves a strong loading of nano-zinc molybdate on the surface of boron nitride nanosheets, effectively integrating the high resistivity characteristics and physical shielding effect of boron nitride nanosheets with the anti-rust effect of zinc molybdate, thus endowing the sheet filler with voltage breakdown resistance and enhanced anti-corrosion function.

[0021] 2. The functional filler prepared by this invention has excellent dispersibility and reactivity with resin, achieving uniform dispersion of the filler in the coating and tight bonding with the film-forming resin, reducing internal defects in the coating, and improving the coating's voltage breakdown resistance and resistance to corrosive media penetration. Attached Figure Description

[0022] Figure 1 This is a microscopic morphology (SEM image) of the voltage breakdown resistant and corrosion-resistant filler prepared in Example 5 of the present invention. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments can enable those skilled in the art to have a more comprehensive understanding of the present invention, but do not limit the present invention in any way.

[0024] The preparation method of the voltage breakdown resistant and corrosion-resistant filler in this invention includes the following steps: (1) Add 1 part by mass of boron nitride sheet to at least one mixed solvent selected from N-methylpyrrolidone, N,N-dimethylformamide, and dimethyl sulfoxide, and place it in an ultrasonic oscillator with a frequency of 80-200 kHz for oscillation. After oscillation for 2-5 h, pour the mixture into a reaction vessel and react at 160-200 °C for 5-12 h. Then filter the reaction solution, and wash the collected precipitate three times alternately with deionized water and anhydrous ethanol. Then disperse it in 50-80 parts by mass of aqueous alcohol solvent, adjust the pH value to 4.0-5.0 with glacial acetic acid, and react at 300 r / min. At a stirring rate of 3 ml / min, 0.05-0.1 parts by weight of at least one silane coupling agent selected from γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane were added to the mixture. The mixture was then refluxed at 60-80°C for 5-10 h. Finally, the precipitate was obtained by filtration. The precipitate was washed three times alternately with deionized water and anhydrous ethanol. The precipitate was then dispersed in a mixture of 80-100 parts by weight of anhydrous ethanol and ethylene glycol at a mass ratio of 1:1 to obtain a modified boron nitride nanosheet dispersion.

[0025] (2) To 100 parts by mass of modified boron nitride nanosheet dispersion, add 0.1-0.3 parts by mass of a mixture of at least one zinc salt from zinc nitrate, zinc acetate, and zinc citrate, with a zinc atom to molybdenum atom molar ratio of 1:1, and at least one molybdate from sodium molybdate and potassium molybdate. After stirring the mixture for 10 min, pour it into a reaction vessel and react at 140-180℃ for 6-24 h. Then filter the reaction solution and collect the precipitate. Wash the precipitate three times alternately with deionized water and anhydrous ethanol. Then disperse it in a mixed solvent composed of at least one solvent from anhydrous ethanol, propylene glycol methyl ether, and N,N-dimethylformamide, and deionized water, wherein the mass ratio of organic solvent to deionized water is 10:1-100:1. Stir at 800 r / min for 2 h to obtain a zinc molybdate modified boron nitride nanosheet dispersion with a solid content of 10%.

[0026] (3) Add at least one pH adjuster from glacial acetic acid, oxalic acid, and formic acid to 1 part by mass of zinc molybdate modified boron nitride nanosheet dispersion to adjust the pH value to 3.0~5.0. Then, add 1~5 parts by mass of ethanol solution of at least one ester compound from tetraethyl orthosilicate, tetrabutyl titanate, and methyl orthosilicate with a mass fraction of 5% at a stirring rate of 1 ml / min under a stirring rate of 800 r / min. After the addition is completed, continue stirring for 8~12 h. Filter the product with a 300 mesh filter cloth. Place the filtrate in a rotary evaporator for concentration to obtain a voltage breakdown resistant and corrosion-resistant filler with a solid content of 30%.

[0027] Example This invention prepared voltage-breakdown resistant and corrosion-resistant fillers through eight embodiments. The experimental data for each embodiment are shown in Table 1 below. The microstructure (SEM image) of the voltage-breakdown resistant and corrosion-resistant filler prepared in Example 5 of this invention is shown below. Figure 1 As shown.

[0028] Table 1. Example Data Table Note: "√" indicates that it is used.

[0029] Detection example 1. Examples of paint preparation and application methods (1) Preparation method of coating: Mix 30 parts by weight of epoxy resin, 60 parts by weight of voltage breakdown anti-corrosion filler and 10 parts by weight of propylene glycol methyl ether, stir for 2 hours to obtain epoxy anti-corrosion coating. (2) Application method of coating: The anti-corrosion coating prepared by the voltage breakdown anti-corrosion filler of the present invention is applied to the surface of the aluminum alloy plate by air spraying.

[0030] (2.1) Cleaning of aluminum alloy plates. Immerse the aluminum alloy plates in a 5% alkaline degreasing agent aqueous solution for 10 min to remove oil, and then rinse with deionized water; then immerse the aluminum alloy plates in a 5% nitric acid aqueous solution for pickling, take them out after 10 min, and rinse with deionized water; then immerse them in deionized water, ultrasonically vibrate for 10 min, take them out, rinse with deionized water, and dry them for later use.

[0031] (2.2) Aluminum alloy sheet spraying. A clean aluminum alloy sheet is placed on the surface of a mesh spraying tray and sprayed using air spraying. The spraying pressure is controlled at 0.5 MPa. During the spraying process, it is essential to ensure a uniform surface coating without sagging or defects. The sprayed sample undergoes heat curing. The heat curing process is as follows: hold at 80℃ for 10 minutes; then raise the temperature to 120℃ and hold for 10 minutes; finally, raise the temperature to 175℃ and hold for 60 minutes. After the coating has cured, the aluminum alloy sheet is flipped and placed on the mesh spraying tray, with the contact surface between the aluminum alloy sheet and the mesh spraying tray facing outwards. This contact surface is then sprayed. The above process is repeated to obtain an aluminum alloy coated sample.

[0032] 2. Performance Testing Methods 2.1 Sampling Method Comparative Example 1: For traditional epoxy coating (zinc-free) anti-corrosion technology, commercially available products were purchased; Comparative Example 2: In contrast to the comparative technology of the present invention, the modified boron nitride nanosheets obtained in step (1) of the invention were directly formulated into fillers with a solid content of about 30%, and samples were prepared according to the above-mentioned coating preparation and usage method. Comparative Example 3: In contrast to the comparative technology of the present invention, the zinc molybdate modified boron nitride nanosheets obtained in step (2) of the invention were directly formulated into a filler with a solid content of about 30%, and a sample was prepared according to the above-mentioned coating preparation and usage method. To address the corrosion protection technology of this invention, samples were prepared using the voltage breakdown resistant corrosion protection fillers prepared in Examples 1-8 according to the above-described coating formulation and application methods.

[0033] 2.2 Test Method: According to the provisions of GB / T 10125-2021, the performance test of neutral salt spray resistance was carried out on each comparison sample.

[0034] According to GB / T 1408.2, the voltage breakdown performance of each comparison sample was tested.

[0035] 2.3 Comparison Results The corrosion resistance of the product of this invention, traditional epoxy coatings, and the comparative technology of this invention are shown in Table 2.

[0036] Table 2 As can be seen from the above comparison, compared with existing epoxy coatings and the comparative technology of this invention, this invention has higher resistance to neutral salt spray (up to about 3.2 times) and resistance to voltage breakdown (up to about 3.3 times).

[0037] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of this invention should be considered within the scope of protection of this invention.

Claims

1. A method for preparing a voltage breakdown resistant anticorrosion functional filler, characterized by, The method comprises the following steps: (1) peeling and surface modifying boron nitride sheets to obtain a modified boron nitride nanosheet dispersion liquid with amino groups grafted on the surface; (2) mixing and reacting the modified boron nitride nanosheet dispersion liquid obtained in step (1) and a mixture of a zinc salt and a molybdate to in-situ grow zinc molybdate on the surface of the modified boron nitride nanosheets, thereby obtaining a zinc molybdate modified boron nitride nanosheet dispersion liquid; (3) adding an ester compound to the zinc molybdate modified boron nitride nanosheet dispersion liquid obtained in step (2) to react, and obtaining the voltage breakdown resistant anticorrosion functional filler through post-treatment.

2. The preparation method of the voltage breakdown resistant and corrosion-resistant filler according to claim 1, characterized in that, Step (1) specifically comprises: adding boron nitride sheets into a solvent and performing ultrasonic oscillation, and then performing hydrothermal reaction; after washing the reaction product, dispersing it in a hydroalcoholic solvent, adjusting the pH to be acidic, and adding a silane coupling agent containing amino groups to perform condensation reflux reaction; after washing the reaction product, dispersing it in a mixed solvent to obtain the modified boron nitride nanosheet dispersion liquid.

3. The preparation method of the voltage breakdown resistant and corrosion-resistant filler according to claim 2, characterized in that, In step (1), the solvent is at least one of N-methylpyrrolidone, N,N-dimethylformamide and dimethyl sulfoxide; The mixed solvent is anhydrous ethanol and ethylene glycol, and the mass ratio is 1:1; The silane coupling agent containing amino groups is at least one of γ-aminopropyl triethoxysilane, N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane and N-β-(aminoethyl)-γ-aminopropyl methyl dimethoxysilane; The mass ratio of the boron nitride sheets to the silane coupling agent containing amino groups is 1:0.05-0.1; The pH is adjusted to 4.0-5.

0.

4. The method for preparing the voltage breakdown resistant and corrosion-resistant filler according to claim 2 or 3, characterized in that, In step (1), the frequency of the ultrasonic oscillation is 80-200 kHz, and the time is 2-5 h; The temperature of the hydrothermal reaction is 160-200 ℃, and the time is 5-12 h; The temperature of the condensation reflux reaction is 60-80 ℃, and the time is 5-10 h.

5. The preparation method of the voltage breakdown resistant and corrosion-resistant filler according to claim 1, characterized in that, In step (2), the zinc salt is at least one of zinc nitrate, zinc acetate and zinc citrate; The molybdate is at least one of sodium molybdate and potassium molybdate; In the mixture of the zinc salt and the molybdate, the molar ratio of zinc atoms to molybdenum atoms is 1:1; The mass ratio of the modified boron nitride nanosheet dispersion liquid to the mixture of the zinc salt and the molybdate is 100:0.1-0.

3.

6. The method for preparing the voltage breakdown resistant and corrosion-resistant filler according to claim 1 or 5, characterized in that, In step (2), the reaction conditions are as follows: reacting at 140-180 ℃ for 6-24 h; after the reaction, washing the product and dispersing it in a mixed solvent composed of an organic solvent and deionized water to obtain the zinc molybdate modified boron nitride nanosheet dispersion liquid, wherein the mass ratio of the organic solvent to the deionized water is 10-100:

1.

7. The method for preparing the voltage breakdown resistant and corrosion-resistant filler according to claim 6, characterized in that, In step (2), the organic solvent is at least one of anhydrous ethanol, propylene glycol methyl ether and N,N-dimethylformamide.

8. The method for preparing the voltage breakdown resistant and corrosion-resistant filler according to claim 1, characterized in that, In step (3), before adding the ester compound, a pH adjuster is used to adjust the pH value of the system to 3.0-5.0; the pH adjuster is at least one of glacial acetic acid, oxalic acid and formic acid.

9. The method of claim 1 or 8, wherein the method is characterized by, In step (3), the ester compound is at least one of tetraethyl orthosilicate, butyl titanate and methyl orthosilicate. When the ester compound is added in the form of a 5% ethanol solution by mass fraction, the solid content of the zinc molybdate modified boron nitride nanosheet dispersion is 10%, and the mass ratio of the ester compound added in the zinc molybdate modified boron nitride nanosheet dispersion is 1:1-5.

10. The method for preparing the voltage breakdown resistant and corrosion-resistant filler according to claim 1, characterized in that, In step (3), the post-treatment comprises: filtering the reaction product, and obtaining the solid content of the voltage breakdown resistant anti-corrosion functional filler of 30% after the obtained filtrate is concentrated.

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