A coating composition, coated article, use

Abstract

The present application belongs to the technical field of corrosion-resistant coating, and particularly relates to a coating composition, a coated part and an application. The coating composition comprises the following components by mass: 6-7 parts of polyester resin, 1-2 parts of titanium white, 0.3-0.5 parts of a curing agent, 0.1-0.5 parts of a leveling agent and 0.1 parts of a modified corrosion-resistant filler; wherein the modified corrosion-resistant filler is obtained by surface modification treatment of the corrosion-resistant filler with a silane coupling agent; the corrosion-resistant filler is a phosphate-based corrosion-resistant filler and / or a metal-based corrosion-resistant filler. By introducing the modified corrosion-resistant filler into the coating system, a dense and stable barrier structure is formed in the coating in the seawater environment, the penetration and diffusion of chloride ions and water are significantly inhibited, and the electrochemical stability at the coating interface is improved. The prepared plastic spraying coating is firmly attached and has a dense film layer, and can effectively delay the corrosion failure of the carbon steel base material in the seawater environment.

Description

Technical Field

[0001] This invention belongs to the field of corrosion-resistant coating technology, and particularly relates to a coating composition, coated parts, and applications. Background Technology

[0002] Seawater environments contain high levels of chloride ions, dissolved oxygen, and various corrosive ions. Combined with complex factors such as tidal erosion, humid heat cycles, and biofouling, these conditions significantly exacerbate the electrochemical corrosion process of steel materials. Prolonged exposure to seawater and the marine atmosphere makes steel surfaces highly susceptible to pitting corrosion, crevice corrosion, exfoliation, and accelerated failure. This is particularly true for electrical distribution boxes, cabinets, supports, and connecting components used in coastal and offshore areas. Under conditions of high salt spray, high humidity, and temperature fluctuations, their structural strength and electrical safety rapidly decline, impacting the reliability and maintenance costs of power systems. Therefore, developing high-performance, long-life anti-corrosion coating systems is of significant engineering importance for steel electrical equipment in seawater environments.

[0003] Powder coatings are widely used in outdoor equipment due to their advantages such as being solvent-free solid powder, having high adhesion, good erosion resistance, and convenient application. In recent years, to improve the impermeability and corrosion resistance of powder coatings in seawater environments, researchers have improved the system by introducing additives, ceramic fillers, or corrosion inhibitors. Existing patents and research on powder coatings mainly focus on improving the application process, appearance, or mechanical properties of the coatings, with relatively limited attention paid to improving the corrosion resistance of powder coatings in high salt spray, seawater, or highly corrosive environments. Invention CN121006136A discloses a method for preparing a solvent-free, durable, superhydrophobic powder coating, producing a robust, solvent-free, and environmentally friendly superhydrophobic powder coating. Powder coating systems are solid particle systems, making it difficult to achieve sufficient dispersion of corrosion inhibitors in the powder system during extrusion and melt mixing. This leads to the agglomeration of corrosion-resistant fillers in the cured film, affecting the coating's density and interfacial barrier capabilities. Summary of the Invention

[0004] In view of the above-mentioned problems in the prior art, the present invention provides a coating composition, a coated part, and an application, which can improve the dispersion of corrosion-resistant fillers in powder, and the coated part has excellent corrosion resistance.

[0005] To achieve the above objectives, the technical solution provided by the present invention is as follows: In a first aspect, this application provides a coating composition comprising the following components in parts by weight: 6-7 parts polyester resin, 1-2 parts titanium dioxide, 0.3-0.5 parts curing agent, 0.1-0.5 parts leveling agent and 0.1 parts modified corrosion-resistant filler; The modified corrosion-resistant filler is obtained by surface modification treatment of corrosion-resistant filler with silane coupling agent; The corrosion-resistant filler is a phosphate-based corrosion-resistant filler and / or a metal-based corrosion-resistant filler.

[0006] Optionally, the phosphate-based corrosion-resistant filler includes aluminum tripolyphosphate and / or zinc phosphate; the metal-based corrosion-resistant filler is zinc powder and / or aluminum powder.

[0007] Optionally, the phosphate-based corrosion-resistant filler is aluminum tripolyphosphate.

[0008] Optionally, the modified corrosion-resistant filler is obtained by adding the corrosion-resistant filler to a hydrolyzed silane coupling agent, reacting it at 20-40℃ for 8-24 h, and then separating and drying it.

[0009] Optionally, the hydrolysis treatment conditions for the silane coupling agent include: adding deionized water to the ethanol solution of the silane coupling agent, stirring for 0.5-2 h to carry out the hydrolysis reaction, and controlling the pH to be 8-11 during the reaction.

[0010] Optionally, the mass fraction of the silane coupling agent in the ethanol solution of the silane coupling agent is 0.5-5 wt%; the volume ratio of deionized water to ethanol is 1:(10-30).

[0011] Optionally, the polyester resin is polyethylene terephthalate; and / or, the titanium dioxide is titanium dioxide; and / or, the curing agent is β-hydroxyalkylamide; and / or, the leveling agent is an acrylate leveling agent.

[0012] Secondly, this application also provides a coated part, comprising: Substrate; and A powder coating formed on the surface of the substrate, the powder coating being formed by curing the coating composition described in the first aspect.

[0013] Optionally, the substrate is a steel substrate.

[0014] Optionally, the steel substrate is a distribution box, cabinet, bracket, or connecting component for use in coastal or offshore areas.

[0015] Thirdly, this application also provides the application of the coating composition described in the first aspect or the coating described in the second aspect in the corrosion protection of steel substrates in a seawater environment.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: This invention introduces the modified corrosion-resistant filler prepared in this application into the coating system, enabling the coating to form a dense and stable barrier structure in a seawater environment. This significantly inhibits the penetration and diffusion of chloride ions and moisture, and improves the electrochemical stability at the coating interface. Artificial seawater immersion electrochemical impedance spectroscopy (EIS) tests show that the resistivity of the powder coating with the added modified corrosion-resistant filler is significantly increased throughout the immersion period, the characteristic arc radius of the Nyquist curve is significantly increased, and the polarization resistance retention ability is significantly enhanced, demonstrating superior corrosion resistance life and long-term protection capability. The powder coating prepared by this invention has a complete structure, strong adhesion, and dense film layer, which can effectively delay the corrosion failure of carbon steel substrates in seawater environments. It is particularly suitable for long-term protection applications of power distribution equipment in coastal areas, docks, and high-salt-fog areas, and has good engineering application value. Attached Figure Description

[0017] Figure 1 The Nyquist plot shows the powder coating without modified filler in Example 1 under artificial seawater immersion conditions. Figure 2 Example 1: Impedance value of powder-coated coating without modified filler under artificial seawater immersion conditions as a function of time; Figure 3 Infrared spectroscopy (a) and XRD pattern (b) of the modified aluminum tripolyphosphate powder coating added to Example 2; Figure 4 Nyquist plot of Example 2 with modified aluminum tripolyphosphate powder coating under artificial seawater immersion conditions; Figure 5 Figure 2 shows the impedance value of an example with modified aluminum tripolyphosphate powder coating under artificial seawater immersion conditions as a function of time. Figure 6 Infrared spectral analysis (a) and XRD pattern (b) of the modified zinc powder powder coating added to Example 3; Figure 7 Nyquist plot of Example 3 with modified zinc powder powder coating under artificial seawater immersion conditions; Figure 8 The impedance value of the modified zinc powder powder coating added to Example 3 changes over time under artificial seawater immersion conditions; Figure 9 SEM images of the powder coatings in Examples 1, 2, and 3; Figure 10 SEM images of the powder coatings of Examples 1, 2 and 3 after 30 days of salt spray testing. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings: Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0019] All reagents and materials used in this example can be purchased routinely. The quantitative experiments involved in the examples were all repeated at least three times, and the results were averaged.

[0020] Raw material source: Polyethylene terephthalate: Wenzhou Meijia New Materials Co., Ltd.; General-purpose acrylic leveling agents: Shanghai Zicheng International Trade Co., Ltd.; Titanium dioxide: Langfang Lanke Chemical Group; Silane coupling agent: Shandong Silicon Science New Materials Co., Ltd.; Zinc powder: Nanjing Wanqing Chemical Glassware Co., Ltd.

[0021] Example 1

[0022] The method for preparing the coated part in this embodiment is as follows: S1. Substrate preparation: The carbon steel substrate is surface treated by pre-degreasing, degreasing, water washing, silanization treatment, and water washing to obtain the substrate to be sprayed. The pretreatment of the substrate can ensure that the substrate surface is clean and dry and enhance the adhesion of the coating.

[0023] S2. Coating preparation: Polyester resin, titanium dioxide, curing agent and leveling agent are mechanically mixed to obtain the coating.

[0024] By mass fraction, it contains: 7 parts polyester resin, 2 parts titanium dioxide powder, 0.5 parts curing agent, and 0.5 parts leveling agent.

[0025] In this embodiment, the polyester resin is polyethylene terephthalate; the titanium dioxide is titanium dioxide; the curing agent is β-hydroxyalkylamide; and the leveling agent is a general-purpose acrylate leveling agent.

[0026] In this embodiment, the particle size of each raw material in the pre-mixed slurry is small, ensuring the flowability and deposition efficiency of the powder during the spraying process, thereby forming a uniform and dense coating. This is not only applicable to spraying technology, but can also effectively improve the deposition rate and fill the tiny pores in the coating. Moreover, the smaller particle size can improve the smoothness of the coating surface and reduce the roughness of the coating.

[0027] S3. Preparation of coated parts: The pre-made slurry obtained in S2 is sprayed onto the substrate to be coated obtained in S1. After the coating is cured at 180°C, a powder coating is obtained with an average thickness of 100 μm. In this embodiment, the coating is applied by electrostatic spraying at room temperature to deposit onto the substrate surface, followed by thermosetting at 180°C. This temperature falls within the low-temperature curing range for powder coatings, ensuring no damage to the substrate or polymer. This process guarantees both the plastic deformation of pigments and fillers and the full melting and filling of the polyester powder, significantly improving the density and surface smoothness of the coating.

[0028] Compared to traditional thermal spraying methods, cold spraying can achieve efficient coating preparation at lower temperatures, reducing energy consumption and thermal pollution to the environment.

[0029] To analyze the seawater corrosion resistance of the coating, an immersion corrosion test was conducted to assess its corrosion resistance. In this test, the samples were immersed in artificial seawater, and electrochemical impedance spectroscopy (EIS) was performed at intervals. To ensure accuracy, the test surface of the coating sample was in full contact with the corrosive medium, while other surfaces were coated with epoxy resin to isolate them from corrosion.

[0030] The electrochemical impedance spectroscopy of the powder-coated coating prepared in this embodiment is as follows: Figure 1 and Figure 2 The initial impedance value is 4.09 × 10⁻⁶. 7 Ω.cm 2 .

[0031] This embodiment also conducts a salt spray test on the powder coating, such as Figure 9 (a) and Figure 10 (a) SEM images of the powder coating before and after a 30-day salt spray test, as shown. Figure 9 (a) The powder coating surface is smooth and dense, providing protection to the substrate. After a 30-day salt spray test, as... Figure 10 (a) The presence of some pores in the powder coating is the main reason for the gradual decline and failure of the powder coating performance, indicating that the barrier ability of the coating is weakened under long-term salt spray environment.

[0032] Example 2

[0033] The coating composition in this embodiment was prepared by the following method: S1. Prepare the substrate according to the same method as in Example 1; S2. Preparation of modified corrosion-resistant fillers: First, the silane coupling agent is hydrolyzed: the silane coupling agent is mixed evenly with ethanol, and at room temperature, deionized water is slowly added to the ethanol solution of the silane coupling agent under stirring (mass ratio: silane coupling agent: ethanol: water = 1:9:1; silane coupling agent: aluminum tripolyphosphate = 0.05:1), causing the silane coupling agent to undergo a hydrolysis reaction (reaction for 2 h under stirring at 500 r / min), forming a modified solution with an active silanol structure; during the hydrolysis process, ammonia water is added to control the pH of the solution to 11; Then, the corrosion-resistant filler undergoes surface modification treatment with silane coupling agent: aluminum tripolyphosphate is slowly added to the hydrolyzed silane coupling agent under continuous stirring, and the surface modification reaction is carried out at 40 ℃ for 8 h, so that the silane coupling agent is adsorbed and condensed on the surface of the filler, thereby forming a stable organosilicon modified layer; after the reaction is completed, the modified filler is obtained by filtration or centrifugation, and then dried at 60 ℃ to obtain the modified corrosion-resistant filler for later use.

[0034] S3: Preparation of coating composition: First, polyester resin, titanium dioxide, curing agent and leveling agent are mechanically mixed at a stirring speed of 1200 r / min for 30 min to obtain a pre-mixed slurry. Then, the modified corrosion-resistant filler obtained in S2 is added to the pre-mixed slurry and mixed for another 20 min to make the filler uniformly dispersed in the powder system, and finally the coating composition is obtained. By mass fraction, it contains 7 parts polyester resin, 1.9 parts titanium dioxide, 0.5 parts curing agent, 0.5 parts leveling agent, and 0.1 parts modified corrosion-resistant filler.

[0035] The polyester resin is polyethylene terephthalate; the titanium dioxide is titanium dioxide; the curing agent is β-hydroxyalkylamide; and the leveling agent is a general-purpose acrylate leveling agent.

[0036] S4. Preparation of coated parts: The coating composition obtained in S3 is sprayed onto the substrate to be coated obtained in S1. After the coating is cured at 180 °C, a powder coating is obtained with an average thickness of 100 μm.

[0037] In this embodiment, the infrared spectrum and XRD pattern of the powder coating before and after corrosion after adding surface-modified aluminum tripolyphosphate corrosion-resistant filler are as follows: Figure 3 As shown. Infrared spectroscopy results indicate that the coating retains the main characteristic absorption peaks of the polyester resin matrix after corrosion, indicating that the main structure of the coating has not undergone severe degradation and the system as a whole has good structural stability. XRD results show that the coating contains characteristic crystal diffraction peaks originating from aluminum tripolyphosphate before corrosion, and no significant phase transition occurred before and after the powder coating, proving its structural stability. Therefore, Figure 3 This demonstrates that the modified aluminum tripolyphosphate was successfully incorporated into the powder coating and played a role in long-term corrosion resistance.

[0038] The electrochemical impedance spectroscopy of the powder-coated coating prepared in this embodiment is as follows: Figure 4 and Figure 5 The initial impedance value is 4.67 × 10⁻⁶. 8 Ω.cm 2 .

[0039] In this embodiment, the impedance value of the powder-coated coating is an order of magnitude higher than that of the powder-coated coating without corrosion-resistant filler, indicating that the powder-coated coating has excellent corrosion resistance. This is because, on the one hand, as an inorganic corrosion-resistant filler, it can effectively fill the micropores inside the coating, improve the coating density, and enhance the physical barrier ability against corrosive media; on the other hand, aluminum tripolyphosphate can slowly release phosphate ions under the action of corrosive media, forming a stable phosphate passivation film at the coating / metal interface, thereby significantly inhibiting the occurrence of electrochemical corrosion reactions. The synergistic effect of the above-mentioned physical shielding effect and chemical corrosion inhibition effect simultaneously increases the coating resistance and the interfacial charge transfer resistance, ultimately leading to a significant increase in the impedance value.

[0040] This embodiment also conducts a salt spray test on the powder coating, such as Figure 9 (b) and Figure 10 (b) SEM images of the powder coating before and after a 30-day salt spray test, as shown. Figure 9 (b) The smooth and dense surface of the powder-coated layer, with evenly distributed fine white particles, indicates that the modified aluminum tripolyphosphate is well dispersed in the powder coating and provides protection to the substrate. After a 30-day salt spray test, as shown... Figure 10 (b) Some pores appeared in the powder coating, but significantly fewer than in the unmodified aluminum tripolyphosphate coating.

[0041] Example 3

[0042] The difference between this embodiment and Embodiment 2 is that: In the preparation of S2 modified corrosion-resistant filler, zinc powder of equal mass is used to replace aluminum tripolyphosphate.

[0043] In this embodiment, the infrared spectrum and XRD pattern of the powder coating before and after corrosion after adding surface-modified zinc powder corrosion-resistant filler are as follows: Figure 6 As shown in the figure. Infrared spectroscopy results indicate that the main characteristic absorption peaks of the organic resin matrix in the coating still exist after corrosion, indicating that the main structure of the coating remains relatively stable. XRD results show that characteristic crystal diffraction peaks originating from metallic zinc can be observed in the coating before and after corrosion, indicating that the filler did not undergo complete dissolution or significant phase transformation under the action of the corrosive medium, and its crystal structure has good environmental stability. Therefore, Figure 6 This demonstrates that the modified zinc powder was successfully incorporated into the powder coating, and the overall composite structure of the powder coating remained stable during corrosion, which is beneficial for achieving long-term effective protective performance.

[0044] The electrochemical impedance spectroscopy of the powder-coated coating prepared in this embodiment is as follows: Figure 7 and Figure 8 The initial impedance value is 8.75 × 10⁻⁶. 7 Ω.cm 2 It maintained good corrosion resistance. Although it decreased somewhat in the medium term, the impedance value rebounded to 1.08 × 10⁻⁶. 8 Ω.cm 2 The resistivity of the powder-coated coating with added zinc powder decreased to some extent during the mid-immersion stage, mainly due to the preferential dissolution of zinc powder as a sacrificial anode. As the corrosion process progresses, the oxides and hydroxides generated from the zinc powder dissolution gradually deposit in the coating pores and at the coating-metal interface, forming a dense corrosion product layer that hinders further penetration of the corrosive medium. This sealing effect of the corrosion products causes a further increase in the coating system's resistance and interfacial charge transfer resistance, manifested as a rebound in impedance, indicating that the coating system possesses good sacrificial protection and self-sealing capabilities.

[0045] This embodiment also conducts a salt spray test on the powder coating, such as Figure 9 (c) and Figure 10 (c) SEM images of the powder coating before and after a 30-day salt spray test, as shown. Figure 9 (c) The powder-coated surface is smooth and dense, and the evenly distributed white fine particles indicate that the modified zinc powder is well dispersed in the powder coating and has a protective effect on the substrate. After a 30-day salt spray test, if... Figure 10 (c) Some pores appeared in the powder coating, but significantly fewer than in the coating without modified zinc powder.

[0046] The powder coating prepared in this embodiment can be used in marine engineering.

[0047] The powder coating is prepared by uniformly mixing titanium dioxide, pigments, corrosion-resistant materials, and thermoplastic polyurethane (TPU) powder in a specific ratio to obtain a pre-mixed slurry for cold spraying. This pre-mixed slurry is then sprayed onto the substrate surface using a low-pressure cold spraying method to form the powder coating. Titanium dioxide, with its high refractive index, exhibits excellent hiding power and whiteness, improving the coating's hardness and abrasion resistance, effectively resisting erosion and wear from corrosive media such as silt in marine environments. Aluminum tripolyphosphate, as an inorganic reinforcing filler, possesses high thermal stability and chemical inertness. Its incorporation into the coating significantly improves its corrosion resistance while enhancing its mechanical strength and density, helping to protect the substrate in acidic, alkaline, or marine corrosive environments. TPU primarily acts as a binder and filler in the coating. During low-pressure cold spraying, it melts and fills micropores and defects in the coating, improving its density and uniformity, and reducing the penetration of corrosive media. Furthermore, the excellent flexibility and abrasion resistance of TPU can compensate for the brittleness of titanium dioxide and aluminum tripolyphosphate coatings, improving the coating's crack resistance, peel resistance, and impact resistance. This method requires simple equipment and is easy to operate, making it suitable for preparing high-performance weather-resistant and corrosion-resistant coatings.

[0048] The powder coating prepared in this embodiment has the following advantages: (1) Resistant to seawater corrosion: This composite coating performs exceptionally well in marine environments, effectively resisting corrosive media in seawater, and is particularly suitable for marine engineering, shipbuilding, offshore platforms, and other fields.

[0049] (2) Long life protection: The various components in the coating work together to provide long-term effective protection, extend the service life of the substrate, and reduce the frequency and cost of maintenance and replacement.

[0050] (3) Wide range of applications: In addition to marine engineering, this composite coating can also be applied to aerospace, chemical equipment, energy industry and other fields that require high wear resistance, high corrosion resistance and high temperature performance, and has a broad market prospect.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A coating composition, characterized in that, The components include the following parts by weight: 6-7 parts polyester resin, 1-2 parts titanium dioxide, 0.3-0.5 parts curing agent, 0.1-0.5 parts leveling agent and 0.1 parts modified corrosion-resistant filler; The modified corrosion-resistant filler is obtained by surface modification treatment of corrosion-resistant filler with silane coupling agent; The corrosion-resistant filler is a phosphate-based corrosion-resistant filler and / or a metal-based corrosion-resistant filler.

2. The coating composition according to claim 1, characterized in that, The phosphate-based corrosion-resistant filler includes aluminum tripolyphosphate and / or zinc phosphate; the metal-based corrosion-resistant filler is zinc powder and / or aluminum powder.

3. The coating composition according to claim 1, characterized in that, The modified corrosion-resistant filler is obtained by adding the corrosion-resistant filler to a hydrolyzed silane coupling agent and reacting it at 20-40℃ for 8-24 h. After separation and drying, the filler is ready.

4. The coating composition according to claim 3, characterized in that, The hydrolysis treatment conditions for silane coupling agents include: adding deionized water to the ethanol solution of the silane coupling agent, stirring for 0.5-2 h to carry out the hydrolysis reaction, and controlling the pH to 8-11 during the reaction.

5. The coating composition according to claim 4, characterized in that, The mass fraction of silane coupling agent in the ethanol solution is 0.5-5 wt%; the volume ratio of deionized water to ethanol is 1:(10-30).

6. The coating composition according to claim 1, characterized in that, The polyester resin is polyethylene terephthalate; and / or, the titanium dioxide is titanium dioxide; and / or, the curing agent is β-hydroxyalkylamide; and / or, the leveling agent is an acrylate leveling agent.

7. A coated part, characterized in that, include: Substrate; And a powder coating formed on the surface of the substrate; The powder coating is formed by curing the coating composition according to any one of claims 1 to 6.

8. The coated part according to claim 7, characterized in that, The substrate is a steel substrate.

9. The coated part according to claim 8, characterized in that, The steel substrate is used for distribution boxes, cabinets, brackets, or connecting components in coastal or offshore areas.

10. The application of the coating composition of any one of claims 1 to 6 or the coating of any one of claims 7 to 9 in the corrosion protection of steel substrates in a seawater environment.

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