A stain-resistant and corrosion-resistant coating for stainless steel surfaces and a method for preparing the same

Abstract

The application discloses a kind of anti-fouling corrosion-resistant coating for stainless steel surface and preparation method thereof, it is related to paint technical field.A kind of anti-fouling corrosion-resistant coating for stainless steel surface, is prepared from the raw materials comprising the following parts by mass: acrylic resin 40-60 parts, nano composite filler 5-15 parts, hydrophobic auxiliary agent 2-6 parts, corrosion inhibition pigment 3-8 parts, functional auxiliary agent 1-4 parts, solvent 20-30 parts, silane coupling agent 0.5-1.5 parts, antioxidant 0.5-1.5 parts.Introduce the novel antioxidant of specific structure (formula 1), compared with traditional commercial product has better compatibility and dispersibility, can efficiently capture free radical and block oxidation chain reaction.This significantly improves the yellowing resistance and weathering stability of coating in high temperature, light environment, prevent coating from losing light or brittle fracture due to oxidation.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to an anti-fouling and corrosion-resistant coating for stainless steel surfaces and its preparation method. Background Technology

[0002] Stainless steel, with its excellent mechanical properties, formability, and basic corrosion resistance, has been widely used in various fields such as building decoration, chemical equipment, marine engineering, and food machinery, becoming an indispensable material in modern industry and people's lives. However, in actual service environments, stainless steel surfaces still face three major challenges that severely restrict their service life and application expansion.

[0003] In terms of corrosion, salt spray in marine environments, acid and alkali media in chemical settings, and chloride ion erosion in humid environments can easily lead to pitting corrosion, crevice corrosion, or stress corrosion cracking on stainless steel surfaces, damaging the structural integrity of the material and causing equipment failure or safety hazards. Traditional anti-corrosion coatings mostly rely on single corrosion-inhibiting pigments, which have problems such as short corrosion resistance and insufficient adhesion to the substrate, making them difficult to adapt to complex and harsh corrosive environments.

[0004] Insufficient stain resistance also hinders the application of stainless steel. Stainless steel surfaces easily attract dust, oil, microorganisms, and other contaminants, affecting not only their appearance but also creating localized corrosive microenvironments that accelerate material degradation. Existing hydrophobic coatings mostly use a single hydrophobic component, which can temporarily reduce surface hydrophilicity, but their stain resistance and durability are poor, leading to eventual failure after long-term use, and often proving difficult to achieve simultaneously with corrosion resistance.

[0005] Furthermore, stainless steel surfaces are prone to oxidation under oxygen, high temperature, or light conditions, forming oxide scale that leads to surface dulling and increased roughness, further exacerbating the vicious cycle of contamination and corrosion. Traditional antioxidants have poor dispersibility in coatings, are prone to agglomeration and failure, and have poor compatibility with other components, making it difficult to achieve long-term antioxidant protection.

[0006] Currently, most stainless steel surface treatment materials on the market focus on optimizing a single performance characteristic, lacking comprehensive coatings that simultaneously offer excellent stain resistance, long-term corrosion resistance, and stable oxidation resistance. Some composite functional coatings suffer from issues such as unreasonable component ratios, poor dispersion uniformity, and complex application processes, failing to meet the high requirements for comprehensive material performance and service life in practical applications. Therefore, developing a stain-resistant, corrosion-resistant, and oxidation-resistant coating with good component synergy and excellent comprehensive performance is of significant practical importance for expanding the application scenarios of stainless steel and reducing maintenance costs. Summary of the Invention

[0007] The purpose of this invention is to address the problems existing in the prior art by providing a stainless steel surface anti-fouling and corrosion-resistant coating and its preparation method, which has good component synergy, uniform dispersion, long-term protection for stainless steel, simple preparation process, adaptability to complex environments, and extends the service life of stainless steel.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A stain-resistant and corrosion-resistant coating for stainless steel surfaces is prepared from raw materials comprising the following parts by weight: 40-60 parts acrylic resin, 5-15 parts nanocomposite filler, 2-6 parts hydrophobic additive, 3-8 parts corrosion-inhibiting pigment, 1-4 parts functional additive, 20-30 parts solvent, 0.5-1.5 parts silane coupling agent, and 0.5-1.5 parts antioxidant; The antioxidant has the structure shown in Formula 1; The structure of Equation 1 is as follows: ; Furthermore, R1 is selected from: hydrogen, fluorine, hydroxyl, and ethyl.

[0009] Furthermore, the nanocomposite filler is composed of nano-titanium dioxide and silicon dioxide in a mass ratio of 1:(1-2).

[0010] Furthermore, the hydrophobic additive is polytetrafluoroethylene wax powder.

[0011] Furthermore, the corrosion-inhibiting pigment is iron oxide red.

[0012] Furthermore, the functional additives include leveling agents and dispersants, with a mass ratio of 1:1.

[0013] Furthermore, the dispersant is BYK-111; the leveling agent is BYK-333.

[0014] Furthermore, the solvent is a mixed solvent composed of propylene glycol methyl ether acetate and isopropanol in a mass ratio of (2-3):1; The silane coupling agent is any one of 3-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, or acetoxypropyltrimethoxysilane.

[0015] Furthermore, the antioxidant is any one of the compounds shown in the following structures: ; .

[0016] A method for preparing an anti-fouling and corrosion-resistant coating for stainless steel surfaces includes the following steps: a. Pre-dispersion: Add 1 / 2 part by weight of the solvent, all parts by weight of the dispersant, nanocomposite filler, silane coupling agent and antioxidant to a dispersion tank, and disperse at a speed of 1000-1500 rpm for 20-40 minutes until the fineness is ≤25μm to obtain a slurry; b. Paint mixing: Reduce the rotation speed to 300-500 rpm, add the acrylic resin, corrosion-inhibiting pigment and 1 / 2 part by weight of solvent to the slurry, stir for 15-25 minutes until uniformly mixed to obtain mixture A; c. Refining: Add the hydrophobic additive and leveling agent to the mixture A, increase the rotation speed to 600-800 rpm, continue stirring for 10-20 minutes to disperse evenly, and obtain mixture B. Filter the obtained liquid through an 80-100 mesh filter screen and let it stand at room temperature for at least 12 hours to obtain the anti-fouling and corrosion-resistant coating for stainless steel surfaces.

[0017] Furthermore, the dispersion process in step a is carried out using a sand mill or a high-speed disperser.

[0018] Furthermore, in step b, the acrylic resin should be preheated to 40-50°C before being added.

[0019] A stain-resistant and corrosion-resistant coating for stainless steel surfaces belongs to the field of curing coating technology.

[0020] This invention addresses the pain points of existing technologies by utilizing the proportions and synergistic effects of various raw material components to construct film-forming barriers, inhibit corrosion sources, control surface fouling, and block oxidation chain reactions. It uses acrylic resin as the film-forming base material, whose film-forming properties provide a physical barrier for the coating, while simultaneously forming a synergistic effect with silane coupling agents. The silane coupling agents chemically connect the resin to the nanocomposite filler and the stainless steel substrate, improving the dispersibility of the filler in the resin and strengthening the adhesion between the coating and the substrate, thus reducing corrosion channels in interfacial gaps. The nanocomposite filler fills the micropores within the resin film, enhancing the coating's density. Its nanoscale size effect, combined with corrosion-inhibiting pigments, forms a physical barrier and chemical passivation. The former blocks the penetration of corrosive media such as water and chloride ions, while the latter forms a passivation film upon contact with the substrate, inhibiting anodic dissolution and extending the corrosion resistance period. In terms of antifouling, the hydrophobic additive constructs a low surface energy layer on the coating surface, reducing the adhesion of pollutants; at the same time, the photocatalytic activity of nano-TiO2 can decompose organic pollutants, and the two work synergistically with the leveling agent; the leveling agent ensures a smooth film formation, avoiding the accumulation of pollutants at defects, thus solving the problem of poor antifouling durability of traditional hydrophobic coatings. For the need for antioxidation, a novel, specifically structured Formula 1 antioxidant can capture free radicals within the coating, blocking the oxidation chain reaction, while the dispersant prevents the antioxidant from agglomerating and failing. Simultaneously, it works synergistically with the resin to encapsulate the substrate, slowing down the oxidation of stainless steel by oxygen and light; the mixed solvent ensures uniform dispersion of all components, fully leveraging the synergistic effect, ultimately achieving simultaneous optimization of antifouling, corrosion resistance, and antioxidation performance, solving the problem of existing coatings having outstanding single performance characteristics but insufficient overall effectiveness.

[0021] Compared with the prior art, the beneficial effects of the present invention are: 1. Multiple synergistic effects significantly enhance corrosion resistance and adhesion: By building chemical bond "bridges" through silane coupling agents, the bonding force between resin, filler and stainless steel substrate is strengthened; combined with the dense filling of micropores by nanocomposite fillers and the chemical passivation effect of corrosion-inhibiting pigments, the penetration channels of corrosive media such as water and chloride ions are effectively cut off, solving the problems of insufficient adhesion and short corrosion resistance cycle of traditional coatings.

[0022] 2. Long-lasting anti-fouling effect through a dual physicochemical mechanism: Hydrophobic additives construct a low surface energy defense line on the surface, combined with the photocatalytic activity of nano-TiO2 to decompose organic stains, and a leveling agent to eliminate microscopic defects on the surface, thus preventing the accumulation of pollutants. This combination of "hydrophobicity + decomposition + leveling" solves the problems of poor anti-fouling durability and easy failure with long-term use of existing single hydrophobic coatings.

[0023] 3. Novel antioxidants significantly enhance anti-aging performance: A novel antioxidant with a specific structure (Formula 1) is introduced, which has better compatibility and dispersibility compared to traditional commercially available products. It can efficiently capture free radicals and block oxidation chain reactions. This significantly improves the coating's resistance to yellowing and weathering stability under high temperature and light conditions, preventing the coating from losing its gloss or becoming brittle due to oxidation. Attached Figure Description

[0024] Figure 1 This is the mass spectrum of antioxidant 1 of the present invention.

[0025] Figure 2 This is the NMR spectrum of antioxidant 1 of the present invention. Detailed Implementation

[0026] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Synthesis example 1 Synthesis of Antioxidant 1:

[0028] Step 1: Under a nitrogen atmosphere, 3.73 g of diisopropylethylamine and 4.00 g of raw material (1) were added to 40 mL of 1,4-dioxane. 3.42 g of raw material (2) was dissolved in 20 mL of 1,4-dioxane. The solution was slowly added dropwise to the above solution while maintaining the temperature below -10℃. After the addition was complete, the mixture was stirred at 40℃ for 12 h. After the reaction was completed, the reaction solution was slowly poured into 600 mL of water at 4℃ and stirred until no more bubbles were generated. The pH of the system was adjusted to neutral with 0.1 mol / L hydrochloric acid. The mixture was separated, the organic phase was retained, and the organic phase was concentrated. The organic phase was purified by silica gel column chromatography using a mixed solvent of n-heptane and ethyl acetate as the eluent. The solution was evaporated to dryness to obtain 5.42 g of intermediate (3). Mass spectrometry (MS+1): 478.

[0029]

[0030] Step 2: Under a nitrogen atmosphere, add 5.42 g of intermediate (3), 2.10 g of starting material (4), 0.1 g of triphenylphosphine, 0.05 g of palladium on carbon, 2.29 g of triethylamine, and 70 ml of toluene to the reaction system. Heat to 120 °C and reflux for 12 hours. After the reaction, evaporate the solvent and perform silica gel column chromatography using a mixture of petroleum ether and ethyl acetate as eluent. Elute again with evaporated solvent to obtain 4.99 g of antioxidant 1. Mass spectrometry (MS+1): 583.

[0031] Synthesis Example 2-Synthesis Example 4 The synthesis of antioxidants 2-4 was carried out by referring to the synthesis method of Synthesis Example 1, except that raw material (2) was replaced, and the rest remained the same as in Synthesis Example 1. The specific structures of raw material (2), antioxidant structures, and mass spectrometry (MS+1) data are shown in Table 1.

[0032] Table 1. Structures of raw materials (2), antioxidants and mass spectrometry (MS+1) data involved in Synthesis Examples 2-4.

[0033]

[0034] Example 1 Preparation of an anti-fouling and corrosion-resistant coating for stainless steel surfaces: 1. Raw material components: Acrylic resin: 50 parts, selected: ACRYDIC56-1155NV: 44.0-46.0%; Nanocomposite filler: 10 parts, selected from nano titanium dioxide and nano silicon dioxide in a mass ratio of 1:1; Hydrophobic additive: 3 parts, selected from: polytetrafluoroethylene wax powder; Corrosion inhibitor pigment: 4 parts, selected: iron oxide red; Functional additives: 2 parts, including leveling agent and dispersant, with a mass ratio of 1:1; wherein the leveling agent is BYK-333 and the dispersant is BYK-111; Solvent: 25 parts, selected as a mixed solvent of propylene glycol methyl ether acetate and isopropanol in a mass ratio of 3:1; Silane coupling agent: 1.1 parts, preferably 3-chloropropyltrimethoxysilane; Antioxidant: 0.9 parts, selected from the antioxidant prepared in Synthesis Example 1.

[0035] 2. Preparation: Raw material pretreatment: Preheat the acrylic resin in a 45℃ constant temperature oven for 30 minutes to ensure good flowability; dry the nanocomposite filler in a 105℃ oven for 2 hours to remove free moisture, and cool it to room temperature before use. a. Pre-dispersion: Add 12.5 parts of mixed solvent (i.e., 1 / 2 part by mass of solvent), 1 part of dispersant (BYK-111), 10 parts of pretreated nanocomposite filler, 1.1 parts of silane coupling agent and 0.9 parts of antioxidant to the dispersion tank of a 500mL high-speed disperser; start the high-speed disperser, adjust the speed to 1200 rpm, and continue dispersing at room temperature (25℃) for 30 minutes. During this period, use a scraper fineness meter to detect the fineness of the slurry in real time until the fineness is ≤25μm, then stop the dispersion to obtain a uniform and stable slurry; b. Paint mixing: Reduce the speed of the high-speed disperser to 400 rpm, and slowly add 50 parts of preheated acrylic resin, 4 parts of corrosion-inhibiting pigment (iron oxide red) and the remaining 12.5 parts of mixed solvent to the above slurry; maintain the stirring speed for 20 minutes, and take samples every 5 minutes to observe the mixing state to ensure that the components are fully mixed and there are no obvious particles or layers, so as to obtain a homogeneous mixture A. c. Refining: Add 3 parts of hydrophobic additive (PTFE wax powder) and 1 part of leveling agent (BYK-333) to mixture A. Increase the speed of the high-speed disperser to 700 rpm and continue stirring for 15 minutes to ensure that the hydrophobic additive and leveling agent are evenly dispersed in the system, thus obtaining mixture B. Filter mixture B using a 90-mesh stainless steel filter to remove a small amount of incompletely dispersed micro-impurities. Place the filtered liquid in a sealed container and allow it to stand and mature at room temperature for 24 hours to obtain a stain-resistant and corrosion-resistant coating for stainless steel surfaces.

[0036] Examples 2-4 A stain-resistant and corrosion-resistant coating for stainless steel surfaces is prepared according to the preparation method of Example 1, except that antioxidant 1 is replaced sequentially with antioxidant 2-antioxidant 4 prepared in Synthesis Examples 2-4, and the rest is the same as in Example 1.

[0037] Comparative Example 1 A stain-resistant and corrosion-resistant coating for stainless steel surfaces is prepared according to the method of Example 1, except that antioxidant 1 is replaced with antioxidant AO-3052 (CAS No.: 61167-58-6), and the rest is the same as in Example 1.

[0038] Comparative Example 2 A stain-resistant and corrosion-resistant coating for stainless steel surfaces is prepared according to the method of Example 1, except that antioxidant 1 is replaced with antioxidant 330 (CAS No.: 1709-70-2), and the rest is the same as in Example 1.

[0039] Comparative Example 3 A stain-resistant and corrosion-resistant coating for stainless steel surfaces is prepared according to the method of Example 1, but without the addition of antioxidants, and otherwise remains the same as in Example 1.

[0040] Comparative Example 4 A stain-resistant and corrosion-resistant coating for stainless steel surfaces is prepared according to the method of Example 1, but without the addition of a leveling agent, and otherwise remains the same as in Example 1.

[0041] Comparative Example 5 A stain-resistant and corrosion-resistant coating for stainless steel surfaces is prepared according to the method of Example 1, without the addition of a dispersant, and otherwise remains the same as in Example 1.

[0042] Performance testing The coating prepared in this embodiment was applied to the surface of a 304 stainless steel test plate (150mm×70mm×3mm) that had been sandblasted (Sa2.5 grade) and degreased with alcohol using a spraying process. The wet film thickness of the coating was controlled to be 60μm. After coating, the coating was leveled at room temperature for 10 minutes and then placed in an 80℃ constant temperature oven for 30 minutes to cure. The dry film thickness of the cured coating was measured to be 45μm by a film thickness gauge.

[0043] 1. Adhesion test: The test was conducted in accordance with GB / T9286-1998 "Cross-cut test for paint and varnish film". The rating range was 0-5, with 0 being the best. The data is shown in Table 2.

[0044] 2. Neutral Salt Spray Corrosion Resistance Test: The test was conducted according to GB / T1771-2007 "Determination of Neutral Salt Spray Resistance of Paints and Varnishes". The sealed test panels were placed in a salt spray chamber, and the spray solution was a 50±5 g / L NaCl solution. The temperature inside the chamber was controlled at 35±2℃. The corrosion condition of the panel surface was observed every 24 hours, and the time (h) at which blistering, rusting, or peeling of the coating occurred was recorded. The data are shown in Table 2.

[0045] 3. Anti-aging (anti-yellowing) test: UVB-313 lamp tube was used, with an irradiance of 0.68W / m². 2 The blackboard temperature was 60℃, and one cycle consisted of 8 hours of light exposure followed by 4 hours of condensation. The test lasted for 2500 hours. After the test, the color difference value (ΔE) of the coating was calculated. The smaller the ΔE, the better the coating's resistance to oxidation and yellowing. The data are shown in Table 2.

[0046] 4. Stain Resistance Test: Take 0.5 mL of machine oil and 0.2 g of carbon black powder respectively, and evenly coat / sprinkle them on different test areas of the test panel (each area is 20 mm × 20 mm). Let them stand at room temperature for 24 hours to simulate the contaminant adhesion process. First, rinse the test panel surface with deionized water (water pressure 0.1 MPa) for 30 seconds, and then gently wipe it 10 times with a lint-free soft cloth (wiping force 5 N). Observe the contaminant residue on the coating surface after cleaning, and classify it into 0-4 levels (Level 0: no residue; Level 1: slight residue, not easily visible to the naked eye; Level 2: obvious residue, can be removed by vigorous wiping; Level 3: some contaminants are difficult to remove; Level 4: a large amount of contaminant residue, cannot be cleaned).

[0047] Table 2

[0048] The antioxidants with specific structures in the embodiments, due to their excellent compatibility and free radical scavenging ability, can effectively block the oxidation chain reaction. Therefore, their anti-aging (anti-yellowing) and auxiliary corrosion resistance performance are significantly better than those of the comparative examples using commercially available antioxidants, and far superior to the comparative examples where the coating rapidly degrades and yellows due to the complete lack of antioxidant protection. At the same time, the lack of functional additives (such as the absence of dispersants or leveling agents in the comparative examples) leads to the agglomeration of nanofillers or the appearance of microscopic defects on the film surface, which damages the density and interfacial bonding of the coating and provides a penetration channel for corrosive media. This results in a significant decline in adhesion and salt spray resistance, which in turn proves the key significance of the three-in-one synergistic effect of "resin-filler-additive" in this invention for achieving long-term anti-fouling and corrosion resistance.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A stain-resistant and corrosion-resistant coating for stainless steel surfaces, characterized in that, The coating is prepared from raw materials comprising the following parts by weight: 40-60 parts acrylic resin, 5-15 parts nanocomposite filler, 2-6 parts hydrophobic additive, 3-8 parts corrosion-inhibiting pigment, 1-4 parts functional additive, 20-30 parts solvent, 0.5-1.5 parts silane coupling agent, and 0.5-1.5 parts antioxidant. The antioxidant has the structure shown in Formula 1; Formula 1: ; In Formula 1, R1 is selected from: hydrogen, fluorine, hydroxyl, and ethyl. The functional additives include leveling agents and dispersants, with a mass ratio of 1:

1.

2. The anti-fouling and corrosion-resistant coating for stainless steel surfaces according to claim 1, characterized in that, The nanocomposite filler is composed of nano-titanium dioxide and silicon dioxide in a mass ratio of 1:(1-2); The hydrophobic additive is polytetrafluoroethylene wax powder.

3. The anti-fouling and corrosion-resistant coating for stainless steel surfaces according to claim 1, characterized in that, The corrosion-inhibiting pigment is iron oxide red.

4. The anti-fouling and corrosion-resistant coating for stainless steel surfaces according to claim 1, characterized in that, The dispersant is BYK-111; the leveling agent is BYK-333.

5. The anti-fouling and corrosion-resistant coating for stainless steel surfaces according to claim 1, characterized in that, The solvent is a mixed solvent composed of propylene glycol methyl ether acetate and isopropanol in a mass ratio of (2-3):1; The silane coupling agent is any one of 3-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, or acetoxypropyltrimethoxysilane.

6. A method for preparing an anti-fouling and corrosion-resistant coating for stainless steel surfaces according to any one of claims 1-5, characterized in that, Includes the following steps: a. Pre-dispersion: Add 1 / 2 part by weight of the solvent, all parts by weight of the dispersant, nanocomposite filler, silane coupling agent and antioxidant to a dispersion tank, and disperse at a speed of 1000-1500 rpm for 20-40 minutes until the fineness is ≤25μm to obtain a slurry; b. Paint mixing: Reduce the rotation speed to 300-500 rpm, add the acrylic resin, corrosion-inhibiting pigment and 1 / 2 part by weight of solvent to the slurry, stir for 15-25 minutes until uniformly mixed to obtain mixture A; c. Refining: Add the hydrophobic additive and leveling agent to the mixture A, increase the rotation speed to 600-800 rpm, continue stirring for 10-20 minutes to disperse evenly, and obtain mixture B. Filter the obtained liquid through an 80-100 mesh filter screen and let it stand at room temperature for at least 12 hours to obtain the anti-fouling and corrosion-resistant coating for stainless steel surfaces.

7. The method for preparing an anti-fouling and corrosion-resistant coating for stainless steel surfaces according to claim 6, characterized in that, The dispersion process in step a is carried out using a sand mill or a high-speed disperser.

8. The method for preparing an anti-fouling and corrosion-resistant coating for stainless steel surfaces according to claim 6, characterized in that, In step b, the acrylic resin should be preheated to 40-50°C before being added.

Images