Water-based polyacrylate acid-erosion-resistant anticorrosive paint and preparation method thereof

Abstract

The application discloses an aqueous polyacrylate acid-erosion-resistant anticorrosive paint and a preparation method thereof. The paint is water-based and single-component, and can be cured at room temperature. The paint is composed of a modified polyacrylate emulsion with a core-shell structure, an aqueous inorganic sol-gel resin, a silica sol, a sericite, titanium dioxide, fumed silicon dioxide, an additive and water. The paint is convenient to operate, has low VOC emission during coating, and is a green and environment-friendly acid-erosion-resistant anticorrosive product.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a room-temperature curing, single-component, waterborne polyacrylate coating that is resistant to acid corrosion, corrosion, and UV aging, can adhere to multiple substrates, and has certain thermal stability, as well as its preparation method. Background Technology

[0002] Acid corrosion is the corrosion behavior of metallic materials under the action of acidic gases (such as sulfides, nitrogen oxides, hydrogen chloride, etc.) or acidic liquids (such as sulfuric acid, nitric acid, hydrochloric acid, acetic acid, etc.). Its main mechanisms are hydrogen evolution corrosion and oxidative corrosion. Unlike neutral and alkaline environments, acidic environments (such as phosphating, sulfonation, desulfurization, denitrification, etc.) accelerate cathodic reactions and increase the corrosion rate of metals. Without proper protection, acid corrosion will damage the shape, color, and mechanical properties of metals, leading to a reduction in the quality grade of products and projects, impaired precision and sensitivity, affecting their usability and even rendering them unusable. In rare cases, it can even cause major accidents resulting in the destruction of machinery and loss of life.

[0003] Among various metal acid corrosion protection solutions, coating protection solutions are widely favored due to their low overall cost, wide application range, convenient construction, and high protection efficiency. Currently, the mainstream acid-resistant coatings are solvent-based epoxy phenolic systems, which require the addition of large amounts of benzene, ester, alcohol, or ketone solvents during preparation and coating processes, resulting in high VOC emissions (400-600 g / L). However, with the introduction of the "Air Pollution Prevention and Control Action Plan," the national policy on limiting volatile organic compounds (VOCs) emissions has been rapidly tightened, and detailed management measures such as total emission limits and paint consumption taxes have been quickly implemented. Reducing VOC emissions from coatings has become an irreversible transformation direction for the coating industry. To meet this challenge, the development of green and environmentally friendly water-based acid-resistant and anti-corrosion coatings is imperative.

[0004] Currently, researchers have made many attempts in the field of water-based acid-resistant coatings, and some results have been applied in the petrochemical industry. However, there are still many problems that need to be improved:

[0005] (1) Inadequate acid resistance. This is mainly due to the high hydrophilicity of water-based coatings. This results in a large number of polar channels remaining in the cured coating, weakening its shielding against corrosive media such as water, vapor, acid, and alkali. In addition, most water-based coatings can only withstand dilute acids at room temperature, and have poor protection against concentrated acids and high-temperature acid solutions. At the same time, the types of acids that water-based solutions can withstand are also relatively limited. Many technical solutions cannot withstand both inorganic and organic acids at the same time, nor are they resistant to oxidizing acids, and cannot achieve the same protective life as similar solvent-based products.

[0006] (2) The problem of weather resistance cannot be solved. At present, the technical solutions with better acid resistance are mainly based on water-based epoxy resin systems. Therefore, the coating is not resistant to ultraviolet rays and is not suitable for acid corrosion protection of the outer surfaces of roofs, pipe corridors, pipelines, storage tanks and other surfaces.

[0007] (3) The two-component scheme is the main one, which has high construction requirements. Improper mixing ratio can easily affect the quality of the project.

[0008] (4) The cost of coatings is too high. For petrochemical auxiliary facilities such as pipe racks and supports with slightly lower performance requirements, the cost-effectiveness of coating is too low, which seriously affects the promotion and use of water-based products.

[0009] (5) Poor overall performance. This is mainly manifested in: short corrosion resistance life, poor substrate adaptability, poor resistance to strong alkalis, and poor thermal stability.

[0010] If we can combine actual protection needs and make reasonable improvements to some of the technical defects of water-based products, the market share of water-based acid-resistant and corrosion-resistant coatings will surely be greatly expanded. Summary of the Invention

[0011] The purpose of this invention is to provide a room-temperature curing, single-component waterborne polyacrylate coating and its preparation method, which is suitable for acidic corrosive environments and possesses excellent corrosion resistance, weather resistance, adhesion to multiple substrates, and certain thermal stability.

[0012] The objective of this invention can be achieved through the following technical solutions:

[0013] A water-based polyacrylate acid-resistant and corrosion-resistant coating, the coating being composed of the following components:

[0014]

[0015] In some preferred technical solutions, the coating is composed of the following components:

[0016]

[0017]

[0018] In the technical solution of this invention, the modified polyacrylate emulsion is prepared through the following steps:

[0019] S1: Water, 20-40% emulsifier, 20-40% methyl methacrylate, 40-60% butyl acrylate, γ-methacryloyloxypropyltrimethoxysilane, vinyltriethoxysilane, and hydrochloric acid with a concentration of 1-10 mol / L are dispersed at high speed and uniformly at 35-50℃ to obtain monomer pre-emulsion 1.

[0020] S2: Water, isobornyl methacrylate, dodecyl mercaptan, the remaining emulsifier, the remaining methyl methacrylate, and the remaining butyl acrylate are dispersed at high speed at 35-50°C to obtain monomer pre-emulsion 2.

[0021] S3: Add 20-30% of monomer preemulsion 1 and 10-30% of potassium persulfate aqueous solution to the reactor, heat to 80-85℃, and stir for 0.5-1h; then, slowly add the remaining monomer preemulsion 1 and 30-50% potassium persulfate aqueous solution dropwise to the reactor; then slowly add monomer preemulsion 2 and the remaining potassium persulfate aqueous solution, and react for 0.5-1.5h after the addition is complete; heat to 90-95℃ and maintain the temperature for 0.5-1.5h; cool to below 50℃, add dimethylethanolamine, and adjust the pH to 7.0-8.0; cool and filter to obtain the modified polyacrylate emulsion.

[0022] The formulation of the modified polyacrylate emulsion is as follows:

[0023]

[0024]

[0025] In the technical solution of this invention: the emulsifier is a mixture of nonylphenol polyoxyethylene ether and sodium dioctyl sulfosuccinate, and the mixing ratio of the two is (1-3):(0.4-0.8).

[0026] In the technical solution of this invention: the aqueous inorganic sol-gel resin is Evonik Dynasylan SIVO 140.

[0027] In the technical solution of this invention: the neutral silica sol is Baxter HN3010 or Baxter HN3020.

[0028] In the technical solution of this invention: the sericite is Gree GA-6 wet-process sericite.

[0029] In the technical solution of this invention: the wetting and dispersing agent is Mingling EDAPLAN 490; the defoamer is TEGOAirex 902W; the substrate wetting agent is TEGO Wet KL 245; the anti-flash rust additive is Haimingsi Deqian NALZINFA179; and the thickener is Haimingsi RHEOLATE 299.

[0030] A method for preparing the above-mentioned waterborne polyacrylate acid-resistant and anti-corrosion coating, the method comprising the following steps:

[0031] S1: Add water, wetting and dispersing agent, and aqueous inorganic sol-gel resin to the paint mixing tank and stir evenly; add titanium dioxide, sericite, fumed silica, and defoamer, and disperse at high speed until uniform, without powder lumps or agglomerates; transfer to a sand mill and grind until the slurry fineness is less than 25μm.

[0032] S2: Add the modified polyacrylate emulsion and neutral silica sol to the slurry obtained in step 1 and stir evenly; add dipropylene glycol butyl ether, substrate wetting agent, and anti-flash rust additive, and continue stirring; add thickener, adjust the system viscosity to 70-110 KU, filter, and the water-based polyacrylate acid-resistant anti-corrosion coating is obtained.

[0033] The beneficial effects of this invention are:

[0034] First, this invention uses a self-synthesized modified polyacrylate emulsion as the main film-forming material. This emulsion is produced using a batch seed emulsion polymerization process, resulting in low latex particle size and narrow particle size distribution, and possessing a controllable core-shell structure. The core layer is a low-T... g Silane-modified copolymers with a high-T shell g This is a copolymer modified with isobornyl methacrylate. The structure effectively encapsulates and stabilizes siloxane groups, preventing hydrolysis and condensation during polymerization and paint preparation. Simultaneously, the flexible core molecular chains can rapidly spread during film formation, releasing active siloxane groups and promoting coupling between active functional groups and the substrate and resin.

[0035] Secondly, this invention selects aqueous inorganic sol-gel resin / silica sol as an auxiliary film-forming agent. This auxiliary film-forming agent can react with siloxanes to further improve the crosslinking degree of the coating, improve the solvent resistance and thermal stability of thermoplastic polyacrylate, and enhance the adhesion of the coating to the metal surface.

[0036] Furthermore, this invention preferentially uses GA-6 wet-process sericite (average particle size 15μm), which has a unique aspect ratio-to-thickness lamellar structure and high chemical stability, as an acid-resistant filler. On the one hand, it can effectively extend the erosion path of corrosive media within the coating and enhance the corrosion protection effect; on the other hand, it can also achieve a fine and smooth coating appearance.

[0037] Finally, this invention adopts a pure water-based material combination scheme, and the VOC content of the coating is less than 100g / L, which is in line with the current policy orientation of emission reduction and carbon reduction.

[0038] The waterborne polyacrylate coating disclosed in this invention has excellent chemical resistance, corrosion resistance, weather resistance, adhesion to multiple substrates, and good thermal stability, and is an economical and convenient waterborne acid-resistant coating solution. Detailed Implementation

[0039] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto:

[0040] The sources of some of the raw materials mentioned in the examples include, but are not limited to, the following websites:

[0041] Evonik Dynasylan SIVO 140:

[0042] https: / / coatings.specialchem.com / product / r-evonik-dynasylan-sivo-140

[0043] Baxter HN3010 or HN3020 neutral silica sol

[0044] http: / / www.99better.cn / product / 11.html

[0045] Gree GA-6 Wet Processed Sericite

[0046] http: / / www.chinagrea.com / p_display.php?id=1

[0047] Mingling EDAPLAN 490 wetting and dispersing agent

[0048] https: / / www.4006787252.com / article_read_14449.html

[0049] TEGO Airex 902W Defoamer

[0050] https: / / www.4006787252.com / article_read_1552.html

[0051] TEGO Wet KL 245 Substrate Wetting Agent

[0052] https: / / b2b.baidu.com / land?id=e385b1bff812d60be157d893996b82b610

[0053] Haiming Sideqian NALZIN FA 179 Anti-Flash Rust Agent

[0054] https: / / www.4006787252.com / article_read_6408.html

[0055] RHEOLATE 299 Thickener

[0056] https: / / b2b.baidu.com / land?id=6f7486f80b1dbaa953cf6f73ed0a8c3d10

[0057] The preparation steps of waterborne polyacrylate acid-resistant and anti-corrosion coatings in Examples 1-3 (material ratios are shown in Table 1) and Comparative Examples 1-5 are as follows (test results are shown in Tables 2 and 3):

[0058] (1) Preparation of modified polyacrylate emulsion:

[0059] 50% water, 1 / 3 emulsifier, 1 / 3 methyl methacrylate, 1 / 2 butyl acrylate, γ-methacryloyloxypropyltrimethoxysilane, vinyltriethoxysilane and hydrochloric acid (5 mol / L) were dispersed at high speed and uniformly at 35-40℃ to obtain monomer pre-emulsion 1.

[0060] The remaining water, isobornyl methacrylate, dodecyl mercaptan, remaining emulsifier, remaining methyl methacrylate, and remaining butyl acrylate are dispersed at high speed and uniformly at 35-40°C to obtain monomer pre-emulsion 2.

[0061] Add 25% of monomer preemulsion 1 and 1 / 5 of potassium persulfate to a reactor, heat to 80-85°C, and stir for 1 hour. Then, slowly add the remaining monomer preemulsion 1 and 2 / 5 of the potassium persulfate aqueous solution dropwise to the reactor over 2 hours. Next, add monomer preemulsion 2 and the remaining potassium persulfate aqueous solution dropwise over 3 hours, and continue the reaction for 1 hour, heating to 90-95°C and holding for 1 hour. Cool to below 50°C, add dimethylethanolamine, cool, and filter to obtain the modified polyacrylate emulsion.

[0062] (2) Preparation of waterborne polyacrylate acid-resistant and anti-corrosion coatings:

[0063] Add water, wetting and dispersing agent EDAPLAN 490, and waterborne inorganic sol-gel resin Evonik Dynasylan SIVO 140 to the paint mixing tank and stir until homogeneous. Add titanium dioxide, GA-6 wet sericite, fumed silica, and Airex 902W defoamer, and disperse at high speed until uniform, without lumps or agglomerates. Transfer to a sand mill and grind until the slurry fineness is less than 25μm.

[0064] Add the modified polyacrylate emulsion and neutral silica sol to the slurry obtained in step 1 and stir evenly; add dipropylene glycol butyl ether, Wet KL 245 substrate wetting agent, and FA 179 anti-flash rust additive, and continue stirring; add RHEOLATE 299 thickener, adjust the viscosity of the system to 70-110 KU, filter, and the water-based polyacrylate acid-resistant anti-corrosion coating is obtained.

[0065] Material proportions for comparative examples 1-5:

[0066] Comparative Example 1: The "double preemulsion" polymerization process in Example 1 was changed to a "single preemulsion" polymerization process, while the remaining preparation process and material ratios remained the same as in Example 1. The specific steps of the single preemulsion process are as follows: Water, emulsifier, methyl methacrylate, butyl acrylate, γ-methacryloyloxypropyltrimethoxysilane, vinyltriethoxysilane, isobornyl methacrylate, dodecyl mercaptan, and hydrochloric acid were dispersed uniformly at high speed at 35-50°C to obtain a monomer preemulsion; 25% of the monomer preemulsion and a portion of the potassium persulfate aqueous solution were added to a reaction vessel, heated to 80-85°C, and stirred for 0.5-1 h. Then, the remaining monomer preemulsion and potassium persulfate aqueous solution were slowly added dropwise to the reaction vessel over 3-5 h. The reaction was continued for 1 h, then heated to 90-95°C and held for 1 h. After cooling to below 50°C, dimethylethanolamine was added, and the pH was adjusted to 7.0-8.0. After cooling and filtration, the modified polyacrylate emulsion can be obtained.

[0067] Comparative Example 2: Replace “3 parts by mass of γ-methacryloxypropyltrimethoxysilane and 1 part by mass of vinyltriethoxysilane” in Example 1 with “4 parts by mass of vinyltriethoxysilane”, and keep the other material ratios the same as in Example 1.

[0068] Comparative Example 3: Replace “12 parts by weight of isoborneol methacrylate” in Example 2 with “12 parts by weight of methyl methacrylate”, and keep the other material ratios the same as in Example 2.

[0069] Comparative Example 4: The "60 parts by weight of modified polyacrylate emulsion, 6 parts by weight of DynasylanSIVO 140, 5 parts by weight of HN3010 silica sol, and 5.8 parts by weight of dipropylene glycol butyl ether" in Example 2 were replaced with "71 parts by weight of modified polyacrylate emulsion and 6.8 parts by weight of dipropylene glycol butyl ether", and the proportions of the remaining materials were the same as in Example 2.

[0070] Comparative Example 5: Replace “5 parts by weight of GA-6 wet-process sericite (15±1.5μm)” in Example 3 with “5 parts by weight of Gree GM-2 mica powder (particle size ≤24μm)”, and the proportions of other materials are the same as in Example 3.

[0071] Table 1. Material addition amounts (parts by mass) for Examples 1-3

[0072]

[0073] Table 2 Main Technical Specifications of Waterborne Polyacrylate Acid-Resistant and Corrosion-Resistant Coatings in Examples 1-3 (Table 2)

[0074]

[0075] Note: [1] The test panel had a single coating and a dry film thickness of 80±5μm. [2] The test panel was a composite coating, with a water-based zinc-rich primer and a water-based epoxy intermediate coat, and the total dry film thickness was 200±10μm.

[0076] Table 3 Main technical indicators of waterborne polyacrylate acid-resistant and anti-corrosion coatings (Comparative Examples 1-5)

[0077]

[0078]

[0079] Note: [1] The test panel had a single coating and a dry film thickness of 80±5μm. [2] The test panel was a composite coating, with a water-based zinc-rich primer and a water-based epoxy intermediate coat, and the total dry film thickness was 200±10μm.

[0080] Test results (Table 2) show that Examples 1-3 all yielded waterborne polyacrylate acid-resistant and corrosion-resistant coatings that can be cured at room temperature, are resistant to acids and alkalis, have excellent adhesion, are resistant to ultraviolet aging, and can withstand high temperatures up to 200°C.

[0081] The core-shell structure obtained by the "double pre-emulsion" seed emulsion polymerization process is crucial to the performance of the coating. If the "double pre-emulsion" seed emulsion polymerization process (Comparative Example 1) is not used, the active silane groups in the resin cannot be properly embedded. They will undergo hydrolysis and condensation during polymerization and storage, thereby destroying the stability of the emulsion, affecting the self-crosslinking of the coating during the curing stage and its coupling reaction with the substrate. This leads to a significant reduction in coating adhesion and crosslinking density, making it unable to effectively shield against corrosive media.

[0082] Secondly, the combination of silane monomers is also crucial. Experiments show that using a specific ratio of long-chain methoxysilanes to short-chain ethoxysilanes yields the best results. Methoxysilanes ensure crosslinking activity, while ethoxysilanes improve storage stability. If all silane monomers are replaced with an equal amount of vinyltriethoxysilane (Comparative Example 2), the self-crosslinking activity of the coating significantly decreases, room temperature curing is incomplete, and acid corrosion resistance cannot be fully realized.

[0083] Third, the appropriate addition of isobornyl methacrylate can improve the chemical resistance and corrosion resistance of the coating. If isobornyl methacrylate is completely replaced with methyl methacrylate (Comparative Example 3), the acid and alkali resistance and salt spray resistance of the coating will be reduced.

[0084] Fourth, the addition of Dynasylan SIVO 140 and silica sol can significantly enhance the thermal stability of the coating, and improve the coating strength and adhesion. Without the addition of Dynasylan SIVO 140 and silica sol (Comparative Example 4), the coating adhesion will decrease significantly, and it will lose its thermal stability, thus becoming unable to withstand acid and alkaline solutions at 50°C.

[0085] Finally, the preferred GA-6 wet-process sericite flake filler exhibits strong compatibility with the film-forming system of this invention. The type, particle size, and ratio of the filler have been rigorously screened and cannot be easily replaced. In Comparative Example 5, the GA-6 wet-process sericite (15±1.5μm) in Example 3 was replaced in equal amounts with Gree GM-2 mica powder (particle size ≤24μm). After the replacement, the shielding efficiency against corrosive media decreased, and the acid and alkali resistance and salt spray resistance of the coating obtained in Comparative Example 5 were inferior to those in Example 3.

Claims

1. A water-based polyacrylate acid-resistant and corrosion-resistant coating, characterized in that... This coating is composed of the following components: 40-80 parts of modified polyacrylate emulsion 3-15 parts of water-based inorganic sol-gel resin 1-15 parts of neutral silica sol 1-15 parts of sericite 10-30 parts of titanium dioxide 0.1-3 parts of fumed silica Wetting and dispersing agent 0.1-5 parts Defoamer 0.1-5 parts 1-10 parts of dipropylene glycol butyl ether Substrate wetting agent 0.1-5 parts Anti-flash rust additive 0.1-10 parts Thickener 0.1-10 parts 1-15 parts water; The modified polyacrylate emulsion is prepared by the following steps: S1: Water, 20-40% emulsifier, 20-40% methyl methacrylate, 40-60% butyl acrylate, γ-methacryloyloxypropyltrimethoxysilane, vinyltriethoxysilane and hydrochloric acid with a concentration of 1-10 mol / L are dispersed at high speed and uniformly at 35-50℃ to obtain monomer pre-emulsion 1. S2: Water, isobornyl methacrylate, dodecyl mercaptan, the remaining emulsifier, the remaining methyl methacrylate, and the remaining butyl acrylate are dispersed at high speed at 35~50℃ to obtain monomer pre-emulsion 2. S3: Add 20-30% of monomer preemulsion 1 and 10-30% of potassium persulfate aqueous solution to the reactor, heat to 80-85℃, and stir for 0.5-1h; then, slowly add the remaining monomer preemulsion 1 and 30-50% potassium persulfate aqueous solution dropwise to the reactor; then slowly add monomer preemulsion 2 and the remaining potassium persulfate aqueous solution, and react for 0.5-1.5h after the addition is complete; heat to 90-95℃ and maintain the temperature for 0.5-1.5h; cool to below 50℃, add dimethylethanolamine, and adjust the pH to 7.0-8.0; cool and filter to obtain the modified polyacrylate emulsion; The dosages of each component in the modified polyacrylate emulsion are as follows: 50-60 parts water Emulsifier 1.5-3.5 parts 10-25 parts of methyl methacrylate 10-18 parts of butyl acrylate 2-5 parts of γ-methacryloyloxypropyltrimethoxysilane Vinyltriethoxysilane 0.5-2.5 parts 6-12 parts of isoborneol methacrylate 0.1-0.8 parts of dodecyl mercaptan 0.1-0.5 parts of potassium persulfate aqueous solution 0.02-0.1 parts hydrochloric acid 0.1-0.4 parts of dimethylethanolamine; The emulsifier is a mixture of nonylphenol polyoxyethylene ether and sodium dioctyl sulfosuccinate, with a mixing ratio of (1~3):(0.4-0.8). The neutral silica sol is Baxter HN3010 or Baxter HN3020; the sericite is Gree GA-6 wet-process sericite.

2. The water-based polyacrylate acid-resistant and corrosion-resistant coating according to claim 1, characterized in that... This coating is composed of the following components: 45-65 parts of modified polyacrylate emulsion 5-11 parts of water-based inorganic sol-gel resin 2-8 parts of neutral silica sol 2-6 parts of sericite 12-22 parts of titanium dioxide 0.1-0.5 parts of fumed silica Wetting and dispersing agent: 0.5-2.0 parts Defoamer 0.1-0.5 parts 3-6 parts of dipropylene glycol butyl ether Substrate wetting agent 0.1-0.5 parts Anti-flash rust additive 0.4-1.0 parts Thickener 0.4-1.0 parts 5-10 parts water.

3. The water-based polyacrylate acid-resistant and corrosion-resistant coating according to claim 1, characterized in that... The aqueous inorganic sol-gel resin is Evonik Dynasylan SIVO 140.

4. The water-based polyacrylate acid-resistant and corrosion-resistant coating according to claim 1, characterized in that... The wetting and dispersing agent is Mingling EDAPLAN 490; the defoamer is TEGO Airex 902W; the substrate wetting agent is TEGO Wet KL245; the anti-flash rust additive is Haimingsi Deqian NALZIN FA 179; and the thickener is Haimingsi RHEOLATE 299.

5. A method for preparing the waterborne polyacrylate acid-resistant and anti-corrosion coating according to claim 1, characterized in that: The method includes the following steps: S1: Add water, wetting and dispersing agent, and aqueous inorganic sol-gel resin to the paint mixing tank and stir evenly; add titanium dioxide, sericite, fumed silica, and defoamer, and disperse at high speed until uniform, without powder lumps or agglomerates; transfer to a sand mill and grind until the slurry fineness is less than 25 μm. S2: Add the modified polyacrylate emulsion and neutral silica sol to the slurry obtained in step 1 and stir evenly; add dipropylene glycol butyl ether, substrate wetting agent, and anti-flash rust additive, and continue stirring; add thickener, adjust the system viscosity to 70~110 KU, filter, and the water-based polyacrylate acid-resistant anti-corrosion coating is obtained.

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