Waterproof and anticorrosive paint and preparation method thereof

Abstract

The application belongs to the technical field of paint, and particularly relates to a waterproof and anticorrosive paint and a preparation method thereof. The paint is prepared from a water-based silicone-acrylate emulsion, a water-based epoxy-modified acrylate emulsion, and a water-based polyurethane dispersion as a film-forming matrix, in combination with a zinc-aluminum-silicon oxy complex corrosion inhibition salt, a tannin dopamine silicon oxide modified graphene sheet, a rust-proof pigment, a filler, a hydrophilic fumed nano-silicon dioxide, and an additive. The paint improves the adhesion, water resistance, salt fog resistance, and permeation resistance of the coating through the synergistic effect of complex corrosion inhibition, sheet shielding, silicon oxide enhancement, and resin crosslinking, and is suitable for waterproof and anticorrosive protection of metal substrates.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a waterproof and anti-corrosion coating and its preparation method. Background Technology

[0002] Waterproof and anti-corrosion coatings are widely used on building metal roofs, steel structure components, bridge ancillary facilities, pipeline exteriors, storage tank exteriors, machinery and equipment shells, and metal substrate surfaces in humid environments. Their main function is to form a continuous protective layer between the substrate and external moisture, oxygen, salt spray, acid and alkali media, and pollutants, thereby delaying substrate corrosion and reducing maintenance costs. With increasingly stringent environmental protection requirements, traditional solvent-based anti-corrosion coatings are gradually being restricted, while water-based coatings have become an important development direction due to their better construction safety, lower odor, and stronger environmental adaptability. Existing water-based silicone-acrylic, water-based epoxy-modified acrylic, and water-based polyurethane resin systems can meet conventional film-forming and adhesion requirements. However, under the combined effects of long-term rain immersion, alternating wet and dry conditions, salt spray corrosion, and outdoor UV aging, the coating film is still prone to problems such as water absorption and swelling, micropore expansion, decreased interfacial adhesion, and localized rusting.

[0003] Currently, a common method to improve the performance of water-based anti-corrosion coatings is to add rust-inhibiting pigments and fillers such as zinc phosphate, aluminum tripolyphosphate, titanium dioxide, mica powder, barium sulfate, talc, and silica to the resin system. These improve corrosion resistance through passivation, filling, and shielding effects. However, ordinary rust-inhibiting pigments mainly rely on passive blocking and slow-release rust-inhibiting ions, resulting in a lack of sustained complexation and corrosion inhibition capabilities at scratches, pinholes, or interface defects. Ordinary flake fillers have limited compatibility with water-based resins, and insufficient dispersion can easily lead to agglomeration defects, which in turn become channels for moisture and corrosive media penetration. Ordinary nanofillers have high surface energy, and even a slightly larger addition can lead to increased system viscosity, poor application leveling, and decreased storage stability. Therefore, relying solely on conventional resins and ordinary pigments and fillers is insufficient to simultaneously achieve waterproofing, corrosion resistance, adhesion, flexibility, durability, and application stability.

[0004] Furthermore, some high-performance waterproof and anti-corrosion coatings employ fluorinated resins, expensive nanomaterials, complex microcapsules, or multi-layer deposition processes to achieve high hydrophobicity and shielding performance. However, these solutions often suffer from high raw material costs, complex preparation steps, difficulties in scaling up production, and high requirements for construction equipment, hindering their widespread application in ordinary metal components and building steel structures. Existing technologies still require the development of waterproof and anti-corrosion coatings with readily available formulations, simple preparation processes, good compatibility with water-based systems, and both active corrosion inhibition and multiple shielding functions. This would allow them to maintain the environmental friendliness and ease of application advantages of water-based coatings while improving the protective stability of the coating film under long-term exposure to humidity, salt spray, rainwater erosion, and corrosive media. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a waterproof and anti-corrosion coating comprising the following components in parts by weight: The following components are listed: 28-42 parts of waterborne silicone-acrylic emulsion, 12-22 parts of waterborne epoxy-modified acrylic emulsion, 5-12 parts of waterborne polyurethane dispersion, 2-6 parts of zinc aluminum phytate silica-oxygen complex corrosion inhibitor, 0.3-1.2 parts of tannin-dopamine silica-oxygen modified graphene sheets, 3-8 parts of zinc phosphate, 2-6 parts of aluminum tripolyphosphate, 4-10 parts of rutile titanium dioxide, 5-12 parts of sericite powder, and 6-15 parts of precipitated barium sulfate. 3-8 parts talc powder, 0.8-2.5 parts hydrophilic fumed nano silica, 1-3.5 parts waterproofing agent, 0.3-1.0 parts dispersant, 0.1-0.5 parts wetting agent, 0.2-0.8 parts defoamer, 1-3.5 parts film-forming aid, 0.8-2.5 parts propylene glycol, 0.5-2.0 parts polycarbodiimide, 0.2-0.8 parts thickener, and 8-18 parts deionized water.

[0006] According to a preferred embodiment of the present invention, the preparation method of the phytate zinc aluminum silicate complex corrosion inhibitor salt includes: A1. By weight, add 8-15 parts of 50% phytic acid aqueous solution to 35-55 parts of deionized water, stir, add 3-7 parts of zinc oxide and 1-4 parts of aluminum hydroxide, continue stirring, add ammonia water, adjust the pH to 4.5-5.8, and obtain a zinc-aluminum phytate complex dispersion; add 4-8 parts of γ-aminopropyltriethoxysilane to a mixture of 10-18 parts of anhydrous ethanol and 4-10 parts of deionized water, stir, and hydrolyze at 25-35℃ to obtain aminosilane hydrolysate; A2. Under stirring, add the aminosilane hydrolysate to the zinc aluminum phytate complex dispersion, react at 35-45℃, add 0.5-1.5 parts of hydrophilic silica, dry, pulverize, and sieve.

[0007] In this invention, the formation process of the zinc-aluminum phytate silica-oxygen complex corrosion inhibitor is based on the chelation reaction between the polyphosphate groups of phytate aqueous solution and metal ions. After adding deionized water to the phytate aqueous solution, multiple phosphate groups in the phytate molecules ionize and form an acidic dispersion system containing multiple hydroxyl and polyphosphate groups. When zinc oxide and aluminum hydroxide are added to this system, zinc oxide reacts with the hydrogen ions generated by the ionization of phytate to release zinc ions. The hydroxyl groups on the surface of aluminum hydroxide coordinate with the phosphate groups in phytate, forming a multidentate chelate structure between the phosphate sites of phytate. The system transforms from an acidic solution into a dispersion containing the zinc-aluminum chelate structure. The addition of ammonia neutralizes the residual hydrogen ions in the phytate, keeping the system's acid-base environment weakly acidic. This prevents the chelate structure from dissociating due to excessive acidity and also avoids the hydrolysis and precipitation of zinc hydroxide and aluminum hydroxide due to excessive alkalinity, resulting in a zinc-aluminum phytate complex dispersion. When γ-aminopropyltriethoxysilane is added to a mixture of anhydrous ethanol and deionized water, the ethoxy groups undergo hydrolysis with water to generate silanol structures and release ethanol, forming an aminosilane hydrolysate. When this aminosilane hydrolysate is added to a zinc-aluminum phytate complex dispersion, dehydration condensation reactions occur between the silanol structures to form a silicon-oxygen network structure. The amino structures and the zinc-aluminum phytate complex structures are bonded through hydrogen bonding, electrostatic adsorption, and coordination. The silanol groups on the surface of the hydrophilic silica participate in hydrogen bonding and silicon-oxygen dehydration condensation reactions, forming a composite system with hydrophilic silica as a carrier and the surface loaded with the zinc-aluminum phytate silicon-oxygen complex structure. After drying, pulverizing, and sieving, the zinc-aluminum phytate silicon-oxygen complex corrosion inhibitor is obtained.

[0008] According to a preferred embodiment of the present invention, in step A1, the hydrolysis time at 25-35°C is 30-60 min.

[0009] According to a preferred embodiment of the present invention, in step A2, the reaction time at 35-45°C is 1-3 hours.

[0010] According to a preferred embodiment of the present invention, the preparation method of the tannin-dopamine-siloxane-modified graphene sheet includes: B1. By weight, add 0.8-2.0 parts of graphene oxide to 80-120 parts of deionized water, disperse, add 1-3 parts of tannic acid and 0.3-1.2 parts of dopamine hydrochloride, add ammonia water, adjust the pH to 8.0-8.8, stir and react at 25-35℃ to obtain tannic acid-dopamine modified graphene dispersion; B2. Add 2-5 parts of tetraethyl orthosilicate to 8-15 parts of anhydrous ethanol and mix to obtain a tetraethyl orthosilicate ethanol solution; add the tetraethyl orthosilicate ethanol solution to a tannin-dopamine modified graphene dispersion, add 0.2-0.6 parts of 25% ammonia water, and react at 30-45℃; after the reaction is complete, filter, wash, dry, pulverize, and sieve.

[0011] In this invention, the formation process of tannin-dopamine-siloxane-modified graphene sheets is based on the chemical reaction of oxygen-containing functional groups on the surface of graphene oxide. After graphene oxide is dispersed in deionized water, the hydroxyl, carboxyl, and epoxy groups on its sheet surface undergo hydrogen bonding with water molecules, causing the graphene oxide sheets to be wetted by water and forming a dispersion. After the addition of tannic acid, multiple phenolic hydroxyl groups in its molecular structure combine with the oxygen-containing functional groups on the surface of graphene oxide through hydrogen bonding, and simultaneously adsorb onto the surface of the graphene oxide sheets through aromatic ring conjugation stacking. After ammonia is added, the acid-base environment of the system is adjusted to a weakly alkaline range. In the weakly alkaline environment, dopamine hydrochloride undergoes an oxidative self-polymerization reaction. After the phenolic hydroxyl group is oxidized to a quinone structure, it generates a polydopamine deposition layer containing catechol and amino groups through intermolecular coupling and cyclization reactions. The polydopamine deposition layer is attached to the surface of graphene oxide sheets through covalent bonds, hydrogen bonds and aromatic ring conjugation stacking, and together with tannic acid, forms an interface layer containing polyphenol structure, which inhibits the stacking between graphene oxide sheets, thus obtaining a tannin-dopamine modified graphene dispersion. Tetraethyl orthosilicate is added to anhydrous ethanol to form a tetraethyl orthosilicate ethanol solution. After adding a tannin-dopamine-modified graphene dispersion, the ethoxy groups in the tetraethyl orthosilicate undergo hydrolysis under ammonia catalysis and in the presence of water to generate silanols and release ethanol. The silanols undergo dehydration condensation reactions to form a silicon-oxygen network structure. The silanol structure undergoes hydrogen bonding and condensation reactions with the hydroxyl and amino groups in the polydopamine deposition layer and tannic acid. The silicon-oxygen network structure is deposited on the surface of the graphene oxide sheet to form a silicon-oxygen modified layer. After filtration, washing, drying, pulverizing and sieving, tannin-dopamine silicon-oxygen modified graphene sheets are obtained.

[0012] According to a preferred embodiment of the present invention, in step B1, the stirring reaction is carried out at 25-35°C for 2-4 hours.

[0013] According to a preferred embodiment of the present invention, in step B2, the reaction time at 30-45°C is 2-5 hours.

[0014] The present invention also provides a method for preparing the aforementioned waterproof and anti-corrosion coating, comprising the following steps: S1. Under stirring, deionized water, dispersant, wetting agent, defoamer and propylene glycol are mixed to obtain an additive dispersion; zinc phosphate, aluminum tripolyphosphate, rutile titanium dioxide, sericite powder, precipitated barium sulfate, talc powder, hydrophilic fumed nano silica, zinc aluminum phytate silica-oxygen complex corrosion inhibitor and tannin dopamine silica-modified graphene sheets are added to the additive dispersion and dispersed to obtain an anti-corrosion and waterproof pigment and filler slurry; S2. Add waterborne silicone-acrylic emulsion, waterborne epoxy-modified acrylic emulsion, and waterborne polyurethane dispersion to the anti-corrosion and waterproof pigment and filler slurry, stir, add waterproofing agent, film-forming aid, defoamer, polycarbodiimide, and thickener, continue stirring, and filter.

[0015] In this invention, the formation process of the waterproof and anti-corrosion coating is as follows: deionized water, dispersant, wetting agent, defoamer and propylene glycol are mixed to form an auxiliary dispersion. The dispersant is adsorbed on the surface of zinc phosphate, aluminum tripolyphosphate, rutile titanium dioxide, sericite powder, precipitated barium sulfate, talc powder, hydrophilic fumed nano silica, zinc aluminum phytate silica complex corrosion inhibitor and tannin dopamine silica modified graphene sheet particles and forms a dual stabilizing layer of electrostatics and steric hindrance. The wetting agent reduces the interfacial tension between the solid particles and the aqueous phase. The defoamer breaks the bubbles by reducing the surface tension of the foam film. Propylene glycol extends the open time by reducing the evaporation rate of the aqueous phase, thus obtaining a uniformly dispersed anti-corrosion and waterproof pigment slurry. The addition of waterborne silicone-acrylic emulsion, waterborne epoxy-modified acrylic emulsion, and waterborne polyurethane dispersion to an anti-corrosion and waterproof pigment and filler slurry forms a continuous aqueous system containing emulsion particles. The silicon-oxygen structure in the waterborne silicone-acrylic emulsion provides hydrolysis resistance to the coating film. The epoxy groups and hydroxyl groups in the waterborne epoxy-modified acrylic emulsion adhere to the substrate surface. The urethane structure in the waterborne polyurethane dispersion provides flexibility to the coating film. The waterproofing agent forms a hydrophobic layer in the porous region of the coating film. The film-forming aid lowers the minimum film-forming temperature of the emulsion particles and promotes the fusion of the emulsion particles to form a film. During the drying process of the coating film, the carbodiimide groups in the polycarbodiimide molecule undergo an addition reaction with the carboxyl groups in the emulsion system to generate an acylurea structure, forming a cross-linked network. The thickener adjusts the viscosity of the aqueous phase through association. After the coating is cured, the zinc aluminum phytate silica complex corrosion inhibitor salt forms a corrosion-inhibiting adsorption layer at the metal substrate interface through the coordination of phosphate and amino groups with metal ions. Tannin dopamine silica-modified graphene sheets, sericite powder, and hydrophilic fumed silica form a layered shielding structure in the coating to extend the penetration path of the corrosive medium. Under the action of the corrosive medium, the phosphate groups released by zinc phosphate and aluminum tripolyphosphate react with metal ions to form a passivation film, resulting in a waterproof and anti-corrosion coating.

[0016] According to a preferred embodiment of the present invention, in step S1, the dispersant is a sodium maleic acid-acrylic acid copolymer dispersant; the wetting agent is an acetylenic diol polyether wetting agent; and the defoamer is a polyether-modified polydimethylsiloxane defoamer.

[0017] According to a preferred embodiment of the present invention, in step S2, the waterproofing agent is n-octyltriethoxysilane emulsion waterproofing agent; the film-forming aid is dodecyl alcohol ester film-forming aid; and the thickener is nonionic associative polyurethane thickener.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention employs a composite film-forming system composed of an aqueous silicone-acrylic emulsion, an aqueous epoxy-modified acrylic emulsion, and an aqueous polyurethane dispersion. The aqueous silicone-acrylic emulsion forms a water-resistant and weather-resistant film structure in the coating, the aqueous epoxy-modified acrylic emulsion improves the adhesion strength between the coating and the metal substrate, and the aqueous polyurethane dispersion improves the flexibility and crack resistance of the coating. After the three emulsions are used together to form a film, the coating can maintain a continuous film structure under conditions of rain immersion, alternating wet and dry conditions, and temperature changes, reducing blistering, cracking, and interfacial peeling of the coating, thereby improving the protective stability of the metal substrate surface.

[0019] (2) The addition of phytic acid zinc aluminum silicate complex corrosion inhibitor and tannin-dopamine silicate modified graphene sheets enhances the interfacial corrosion inhibition and media barrier properties of the coating. The phytic acid zinc aluminum silicate complex corrosion inhibitor can form an adsorption layer containing phosphate, zinc and aluminum species, and silicate structure at the metal substrate interface, reducing the effect of corrosive media on the metal surface; the tannin-dopamine silicate modified graphene sheets form a sheet barrier structure in the coating film, extending the penetration path of moisture, oxygen, and corrosive ions. Zinc phosphate and aluminum tripolyphosphate form insoluble deposits after the corrosive media enters the coating film, which, together with the phytic acid zinc aluminum silicate complex corrosion inhibitor, reduce the corrosion rate of the metal substrate surface.

[0020] (3) This invention fills the pores of the coating film with rutile titanium dioxide, sericite powder, precipitated barium sulfate, talc powder, and hydrophilic fumed silica, thereby improving the density and impermeability of the coating. The waterproofing agent forms a hydrophobic structure on the surface and pore areas of the coating film, reducing the rate at which water enters the coating film; the dispersant and wetting agent improve the dispersion uniformity of pigments and fillers in the aqueous phase; the defoamer reduces bubble defects generated during dispersion and construction; the film-forming aid promotes the fusion of emulsion particles to form a film; propylene glycol regulates the open time during construction; polycarbodiimide participates in resin crosslinking and improves the water resistance of the coating film; and the thickener adjusts the viscosity of the system. The resulting waterproof and anti-corrosion coating has the technical effects of stable adhesion, high water resistance, stable salt spray resistance, strong impermeability, and suitable construction rheology. Detailed Implementation

[0021] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0022] Example 1

[0023] This embodiment provides a method for preparing a waterproof and anti-corrosion coating, the steps of which include: S1. Under stirring, 13g of deionized water, 0.65g of dispersant, 0.3g of wetting agent, 0.2g of defoamer and 1.65g of propylene glycol are mixed and stirred at 500r / min for 15min at 25°C to obtain an additive dispersion. 5.5g of zinc phosphate, 4g of aluminum tripolyphosphate, 7g of rutile titanium dioxide, 8.5g of sericite powder, 10.5g of precipitated barium sulfate, 5.5g of talc powder, 1.65g of hydrophilic fumed nano silica, 4g of phytic acid zinc aluminum silicate complex corrosion inhibitor prepared in step A2 and 0.75g of tannin-dopamine silicate modified graphene sheets prepared in step B2 are dispersed at 1200r / min for 45min, controlling the fineness to 35μm, to obtain an anti-corrosion and waterproof pigment and filler slurry.

[0024] S2. Add 35g of waterborne silicone-acrylic emulsion (45% solids content, purchased from Guangzhou Binlong Chemical Co., Ltd.), 17g of waterborne epoxy-modified acrylic emulsion (45% solids content, purchased from Greenlink (Jining) Chemical Technology Co., Ltd.), and 8.5g of waterborne polyurethane dispersion (35% solids content, purchased from Guangdong Xidun New Material Technology Co., Ltd.) to the anti-corrosion and waterproof pigment and filler slurry obtained in step S1. Stir at 500r / min for 25min, then add 2.25g of waterproofing agent (40% solids content) and 2.25g of film-forming aid. 0.2g of defoamer, 1.25g of polycarbodiimide, and 0.5g of thickener (solid content 25%) were stirred at 400r / min for 30min and filtered through a 100μm screen to obtain a waterproof and anti-corrosion coating. The dispersant was a sodium maleic acid-acrylic acid copolymer dispersant, the wetting agent was an acetylsene glycol polyether wetting agent, the defoamer was a polyether-modified polydimethylsiloxane defoamer, the waterproofing agent was an n-octyltriethoxysilane emulsion waterproofing agent, the film-forming aid was a dodecyl alcohol ester film-forming aid, and the thickener was a nonionic associative polyurethane thickener.

[0025] Preparation steps of zinc aluminum phytate silica-oxygen complex corrosion inhibitor salt: A1. By mass, add 45g of deionized water and 11.5g of phytic acid aqueous solution (mass fraction 50%) to the reaction vessel, stir at 500r / min for 15min at 25°C, add 5g of zinc oxide and 2.5g of aluminum hydroxide, continue stirring at 600r / min for 40min to disperse zinc oxide and aluminum hydroxide in the phytic acid aqueous solution, add 1.2g of ammonia water dropwise to adjust the pH to 5.15, continue stirring for 20min to obtain a zinc-aluminum phytate complex dispersion; add 6g of γ-aminopropyltriethoxysilane to a mixture of 14g of anhydrous ethanol and 7g of deionized water, stir at 400r / min at 30°C for 45min to hydrolyze, to obtain an aminosilane hydrolysate.

[0026] A2. Under stirring, the aminosilane hydrolysate obtained in step A1 is added dropwise to the phytate zinc aluminum complex dispersion obtained in step A1. After the addition is completed, the mixture is reacted at 500 r / min at 40°C for 2 h. 1 g of hydrophilic silica is added, and stirring is continued for 30 min. The resulting slurry is dried at 70°C for 8 h, pulverized, and sieved through a 75 μm sieve to obtain phytate zinc aluminum silica complex corrosion inhibitor.

[0027] Preparation steps of tannin-dopamine-siloxane modified graphene sheets: B1. By mass, 1.4 g of graphene oxide was added to 100 g of deionized water and dispersed at 800 r / min for 30 min at 25°C to obtain a graphene oxide dispersion. 2 g of tannic acid and 0.75 g of dopamine hydrochloride were added to the graphene oxide dispersion and stirred for another 20 min. 1.3 g of ammonia was added dropwise to adjust the pH to 8.4. The mixture was stirred at 500 r / min for 3 h at 30°C to obtain a tannin-dopamine modified graphene dispersion.

[0028] B2. Add 3.5g of tetraethyl orthosilicate to 11.5g of anhydrous ethanol and stir at 400r / min for 15min to obtain a tetraethyl orthosilicate ethanol solution. Add the tetraethyl orthosilicate ethanol solution dropwise to the tannin-dopamine modified graphene dispersion prepared in step B1, add 0.4g of ammonia water, and react at 37.5°C and 500r / min for 3.5h. After the reaction is completed, filter, wash three times with deionized water, wash once with anhydrous ethanol, dry at 60°C for 8h, pulverize and sieve using a 75μm sieve to obtain tannin-dopamine silicon oxide modified graphene sheets.

[0029] Example 2

[0030] The key difference between this embodiment and Embodiment 1 is that this embodiment provides a method for preparing a waterproof and anti-corrosion coating, comprising the following steps: S1. Under stirring, 8g of deionized water, 0.3g of dispersant, 0.1g of wetting agent, 0.1g of defoamer and 0.8g of propylene glycol are mixed and stirred at 500r / min for 15min at 25°C to obtain an additive dispersion. 3g of zinc phosphate, 2g of aluminum tripolyphosphate, 4g of rutile titanium dioxide, 5g of sericite powder, 6g of precipitated barium sulfate, 3g of talc powder, 0.8g of hydrophilic fumed nano silica, 2g of phytic acid zinc aluminum silicate complex corrosion inhibitor prepared in step A2, and 0.3g of tannin-dopamine silicate modified graphene sheets prepared in step B2 are added sequentially to the additive dispersion. The mixture is dispersed at 1200r / min for 45min, controlling the fineness to 45μm, to obtain an anti-corrosion and waterproof pigment and filler slurry.

[0031] S2. Add 28g of waterborne silicone-acrylic emulsion, 12g of waterborne epoxy-modified acrylic emulsion, and 5g of waterborne polyurethane dispersion to the anti-corrosion and waterproof pigment and filler slurry obtained in step S1. Stir at 500r / min for 25min. Add 1g of waterproofing agent, 1g of film-forming aid, 0.1g of defoamer, 0.5g of polycarbodiimide, and 0.2g of thickener. Continue stirring at 400r / min for 30min. Filter using a 100μm filter to obtain a waterproof and anti-corrosion coating. The dispersant is a sodium maleic acid-acrylic acid copolymer dispersant, the wetting agent is an acetylsene glycol polyether wetting agent, the defoamer is a polyether-modified polydimethylsiloxane defoamer, the waterproofing agent is an n-octyltriethoxysilane emulsion waterproofing agent, the film-forming aid is a dodecyl alcohol ester film-forming aid, and the thickener is a nonionic associative polyurethane thickener.

[0032] Preparation steps of zinc aluminum phytate silica-oxygen complex corrosion inhibitor salt: A1. Add 35g of deionized water and 8g of phytic acid aqueous solution to the reaction vessel, stir at 500r / min for 15min at 25°C, add 3g of zinc oxide and 1g of aluminum hydroxide, continue stirring at 600r / min for 40min to disperse zinc oxide and aluminum hydroxide in the phytic acid aqueous solution, add 0.8g of ammonia water dropwise to adjust the pH to 4.5, continue stirring for 20min to obtain a zinc-aluminum phytate complex dispersion; add 4g of γ-aminopropyltriethoxysilane to a mixture of 10g of anhydrous ethanol and 4g of deionized water, stir at 400r / min at 25°C for 30min to hydrolyze, to obtain an aminosilane hydrolysate.

[0033] A2. Under stirring, the aminosilane hydrolysate obtained in step A1 is added dropwise to the phytic acid zinc aluminum complex dispersion obtained in step A1. After the addition is completed, the mixture is reacted at 35°C and 500 r / min for 1 h. 0.5 g of hydrophilic silica is added, and stirring is continued for 30 min. The resulting slurry is dried at 70°C for 8 h, pulverized, and sieved through a 75 μm sieve to obtain the phytic acid zinc aluminum silica-oxygen complex corrosion inhibitor.

[0034] Preparation steps of tannin-dopamine-siloxane modified graphene sheets: B1. Add 0.8g of graphene oxide to 80g of deionized water and disperse at 800r / min for 30min at 25°C to obtain a graphene oxide dispersion. Add 1g of tannic acid and 0.3g of dopamine hydrochloride to the graphene oxide dispersion and continue stirring for 20min. Add 0.5g of ammonia water dropwise to adjust the pH to 8.0. Stir the reaction at 500r / min at 25°C for 2h to obtain a tannin-dopamine modified graphene dispersion.

[0035] B2. Add 2g of tetraethyl orthosilicate to 8g of anhydrous ethanol and stir at 400r / min for 15min to obtain a tetraethyl orthosilicate ethanol solution. Add the tetraethyl orthosilicate ethanol solution dropwise to the tannin-dopamine modified graphene dispersion prepared in step B1, add 0.2g of ammonia, and react at 30°C and 500r / min for 2h. After the reaction is complete, filter, wash 3 times with deionized water, wash once with anhydrous ethanol, dry at 60°C for 8h, pulverize and sieve using a 75μm sieve to obtain tannin-dopamine silicon oxide modified graphene sheets.

[0036] Example 3

[0037] The key difference between this embodiment and Embodiment 1 is that this embodiment provides a method for preparing a waterproof and anti-corrosion coating, comprising the following steps: S1. Under stirring, 18g of deionized water, 1g of dispersant, 0.5g of wetting agent, 0.4g of defoamer and 2.5g of propylene glycol are mixed and stirred at 500r / min for 15min at 25°C to obtain an additive dispersion. 8g of zinc phosphate, 6g of aluminum tripolyphosphate, 10g of rutile titanium dioxide, 12g of sericite powder, 15g of precipitated barium sulfate, 8g of talc powder, 2.5g of hydrophilic fumed nano silica, 6g of phytic acid zinc aluminum silicate complex corrosion inhibitor prepared in step A2, and 1.2g of tannin-dopamine silicate modified graphene sheets prepared in step B2 are added sequentially to the additive dispersion. The mixture is dispersed at 1200r / min for 45min, controlling the fineness to 20μm, to obtain an anti-corrosion and waterproof pigment and filler slurry.

[0038] S2. Add 42g of waterborne silicone-acrylic emulsion, 22g of waterborne epoxy-modified acrylic emulsion, and 12g of waterborne polyurethane dispersion to the anti-corrosion and waterproof pigment and filler slurry obtained in step S1. Stir at 500r / min for 25min. Add 3.5g of waterproofing agent, 3.5g of film-forming aid, 0.4g of defoamer, 2g of polycarbodiimide, and 0.8g of thickener. Continue stirring at 400r / min for 30min. Filter using a 100μm filter to obtain a waterproof and anti-corrosion coating. The dispersant is a sodium maleic acid-acrylic acid copolymer dispersant, the wetting agent is an acetylsene glycol polyether wetting agent, the defoamer is a polyether-modified polydimethylsiloxane defoamer, the waterproofing agent is an n-octyltriethoxysilane emulsion waterproofing agent, the film-forming aid is a dodecyl alcohol ester film-forming aid, and the thickener is a nonionic associative polyurethane thickener.

[0039] Preparation steps of zinc aluminum phytate silica-oxygen complex corrosion inhibitor salt: A1. Add 55g of deionized water and 15g of phytic acid aqueous solution to the reaction vessel, stir at 500r / min for 15min at 25°C, add 7g of zinc oxide and 4g of aluminum hydroxide, continue stirring at 600r / min for 40min to disperse zinc oxide and aluminum hydroxide in the phytic acid aqueous solution, add 1.8g of ammonia water dropwise to adjust the pH to 5.8, continue stirring for 20min to obtain a zinc-aluminum phytate complex dispersion; add 8g of γ-aminopropyltriethoxysilane to a mixture of 18g of anhydrous ethanol and 10g of deionized water, stir at 400r / min at 35°C for 60min to hydrolyze, to obtain an aminosilane hydrolysate.

[0040] A2. Under stirring, the aminosilane hydrolysate obtained in step A1 is added dropwise to the phytate zinc aluminum complex dispersion obtained in step A1. After the addition is completed, the mixture is reacted at 45°C and 500 r / min for 3 h. 1.5 g of hydrophilic silica is added, and stirring is continued for 30 min. The resulting slurry is dried at 70°C for 8 h, pulverized, and sieved through a 75 μm sieve to obtain the phytate zinc aluminum silica complex corrosion inhibitor.

[0041] Preparation steps of tannin-dopamine-siloxane modified graphene sheets: B1. Add 2g of graphene oxide to 120g of deionized water and disperse at 800r / min for 30min at 25°C to obtain a graphene oxide dispersion. Add 3g of tannic acid and 1.2g of dopamine hydrochloride to the graphene oxide dispersion and continue stirring for 20min. Add 2.5g of ammonia water dropwise to adjust the pH to 8.8. Stir at 500r / min at 35°C for 4h to obtain a tannin-dopamine modified graphene dispersion.

[0042] B2. Add 5g of tetraethyl orthosilicate to 15g of anhydrous ethanol and stir at 400r / min for 15min to obtain a tetraethyl orthosilicate ethanol solution. Add the tetraethyl orthosilicate ethanol solution dropwise to the tannin-dopamine modified graphene dispersion prepared in step B1, add 0.6g of ammonia water, and react at 45°C and 500r / min for 5h. After the reaction is completed, filter, wash 3 times with deionized water, wash once with anhydrous ethanol, dry at 60°C for 8h, pulverize and sieve using a 75μm sieve to obtain tannin-dopamine silicon oxide modified graphene sheets.

[0043] Comparative Example 1

[0044] The difference between this comparative example and Example 1 is that, in step S1, instead of adding 4g of zinc aluminum phytate silica complexing corrosion inhibitor, 4g of hydrophilic silica is added. The rest is the same as in Example 1.

[0045] Comparative Example 2

[0046] The difference between this comparative example and Example 1 is that, in step S1, instead of adding 0.75g of tannin-dopamine-siloxane modified graphene sheets, 0.75g of graphene oxide is added; otherwise, the same applies as in Example 1.

[0047] Comparative Example 3

[0048] The difference between this comparative example and Example 1 is that, in step S1, instead of adding 4g of phytate zinc aluminum silica-oxygen complex corrosion inhibitor salt and 0.75g of tannin dopamine silica-modified graphene sheet, 4g of hydrophilic silica and 0.75g of graphene oxide are added. The rest is the same as in Example 1.

[0049] The performance of the waterproof and anti-corrosion coatings obtained in Examples 1-3 and Comparative Examples 1-3 were tested in accordance with national and industry standard testing specifications.

[0050] Waterproof and anti-corrosion coatings prepared in Examples 1, 2, 3, 1, 2, and 3 were used as test samples. Cold-rolled steel plates with dimensions of 150mm × 70mm × 1mm were selected as substrates. Before the test, the surface of the steel plate was sanded in the same direction with 400-grit sandpaper to remove the surface oxide layer and dust. The plates were wiped twice with anhydrous ethanol and placed in an environment of 23°C and 50% relative humidity for 30 minutes to equilibrate. The coating was prepared on the surface of the steel plate by scraping. Three parallel test plates were prepared for each test item. After the coating was prepared, it was cured in an environment of 23°C and 50% relative humidity for 7 days. The dry film thickness was measured using a film thickness meter and controlled to be 80μm ± 5μm.

[0051] The drying time test was conducted as follows: Each group of waterproof and anti-corrosion coatings was evenly applied to the surface of a clean glass plate, ensuring a consistent wet film thickness. The plates were then placed in an environment of 23°C and 50% relative humidity. The surface drying test was conducted when the coating surface did not adhere to the finger and left no obvious marks. The actual drying test was conducted when the coating did not adhere, break, or leave obvious indentations after being pressed. The surface drying time and actual drying time were recorded separately. The arithmetic mean of the test results of 3 test plates in each group was taken, with the unit being hours.

[0052] The cross-cut adhesion test is as follows: A flat area is selected on the cured coating surface. A cross-cutting tool with a blade spacing of 2mm is used to cut the coating along mutually perpendicular directions and cut through to the substrate to form a regular grid. After forming a grid, a soft brush is used to lightly brush along the diagonal direction 5 times. A pressure-sensitive adhesive tape with a width of 25mm is applied and pressed firmly to ensure full contact between the tape and the coating. The tape is continuously peeled off at an angle of about 60° within 90 seconds. The coating peeling off at the cut edges and intersections is observed and rated from 0 to 5. A grade of 0 indicates that the cut edges are smooth and there is no coating peeling. The worst grade among the 3 test panels is taken.

[0053] The pull-off adhesion test is performed as follows: A 20mm diameter metal test column is bonded to the cured coating surface with two-component epoxy adhesive. After curing at 23°C for 24 hours, the coating is cut perpendicularly through the edge of the test column to the substrate. The test plate is fixed in the pull-off adhesion tester, and a load is applied uniformly in a direction perpendicular to the coating surface. The maximum pull-off strength when the coating experiences interfacial failure or cohesive failure is recorded. Test results with more than 50% of the adhesive layer being damaged are considered invalid. The arithmetic mean of 3 valid test values ​​for each group is taken, and the unit is MPa.

[0054] The flexibility test is as follows: After curing, the coating test plate is conditioned in an environment of 23°C and 50% relative humidity for 1 hour, with the coating surface facing outward and bend smoothly along the shaft. The test is carried out sequentially using shafts of different diameters. After bending, the coating is observed under normal vision conditions to see if cracks, peeling or separation from the substrate occurs in the bending area. The smallest shaft diameter when no cracks, peeling or separation occurs is taken as the test result, and the unit is mm.

[0055] The water resistance test was conducted as follows: the back and edges of the cured coating test panel were sealed with a mixture of paraffin and rosin, with a sealing width of not less than 5 mm. After the sealing material cured, the test panel was vertically immersed in 23°C deionized water to a depth of not less than 2 / 3 of the test panel height. After continuous immersion for 240 hours, the test panel was removed, the surface moisture was absorbed with filter paper, and the panel was placed in an environment of 23°C and 50% relative humidity for 2 hours. The appearance of the coating was observed to see if blistering, cracking, peeling, or rusting occurred, and the appearance was recorded.

[0056] The neutral salt spray test is conducted as follows: After curing, the back and edges of the coating test panel are sealed. A cross line is drawn in the center of the coating to the substrate using a knife. The line length is 50 mm and the line width is no more than 1 mm. The test panel is placed in a salt spray test chamber at a 20° angle to the vertical direction. A 50 g / L ± 5 g / L sodium chloride solution is used. The test chamber temperature is controlled at 35°C ± 2°C, and the pH of the collected solution is controlled at 7.0. The spraying is continuous for 1000 h. After the test, the surface salt deposits are gently rinsed with running water. The panel is then placed in an environment of 23°C and 50% relative humidity for 2 h. The width of corrosion expansion on one side of the scratch is measured. The result is taken as the arithmetic mean of 3 test panels, in mm. At the same time, the blistering grade, rust grade, and cracking grade of the coating are evaluated. Grade 0 indicates that no corresponding defects have appeared.

[0057] The performance test data above are shown in Table 1.

[0058] Table 1: Performance Test Results

[0059]

[0060] The test results in Table 1 clearly show that Examples 1-3, compared with Comparative Examples 1-3, solved the problems of insufficient adhesion of existing water-based waterproof and anti-corrosion coatings on metal substrates, easy blistering and rusting after immersion in water, obvious scratches and corrosion in salt spray environment, insufficient dispersion of lamellar fillers, and decreased coating flexibility.

[0061] First, the drying times of Examples 1-3 were 0.8-1.0h for surface drying and 10.5-12.0h for complete drying, which were basically at the same level as those of Comparative Examples 1-3 (0.8-0.9h for surface drying and 10.8-11.6h for complete drying). This indicates that the addition of phytic acid zinc aluminum silicate corrosion inhibitor and tannin dopamine silicate modified graphene sheets did not significantly prolong the surface drying and complete drying processes of the water-based coating, and the coating still maintained good workability.

[0062] Secondly, the cross-cut adhesion of Examples 1-3 was all grade 0, and the pull-off adhesion was 5.8 MPa, 5.2 MPa and 5.5 MPa, respectively, which was significantly better than the cross-cut adhesion grades 1, 1 and 2 of Comparative Examples 1-3 and the pull-off adhesion of 4.1 MPa, 4.4 MPa and 3.3 MPa. This indicates that the zinc aluminum phytate silica complex corrosion inhibitor can enhance the bonding between the coating and the metal substrate and inorganic pigments and fillers through the zinc aluminum phytate complex structure and silica structure. The tannin dopamine silica modified graphene sheet can reduce the interface defects caused by the agglomeration of sheets when graphene oxide is directly added. The synergistic effect of the two improves the overall adhesion stability of the coating.

[0063] Furthermore, the flexibility of Examples 1-3 was 1 mm, while that of Comparative Examples 1-3 was 2 mm, 2 mm, and 3 mm, respectively. This indicates that the phytic acid zinc aluminum silicate complex corrosion inhibitor and the tannin-dopamine silicate modified graphene sheets in the examples resulted in a more uniform distribution of the inorganic corrosion inhibitor components and sheet materials in the resin system, reducing stress concentration during bending and solving the problem of decreased flexibility in existing high-filler anti-corrosion coatings due to filler agglomeration. Regarding water resistance, Examples 1-3 showed no blistering, cracking, peeling, or rusting after 240 hours of immersion in water.

[0064] Comparative Example 1 showed slight blistering and slight rusting, Comparative Example 2 showed slight blistering, and Comparative Example 3 showed blistering, slight peeling, and slight rusting. This indicates that when phytate zinc aluminum silicate complex corrosion inhibitor salt is lacking, the metal interface corrosion inhibition adsorption layer is insufficient. When tannin dopamine silicate modified graphene sheets are lacking, the sheet shielding structure and dispersion stability decrease. When both phytate zinc aluminum silicate complex corrosion inhibitor salt and tannin dopamine silicate modified graphene sheets are lacking, coating pore defects, interface water absorption, and corrosive medium penetration are more obvious.

[0065] In terms of salt spray performance, after 1000 hours of neutral salt spray, the unilateral corrosion spread width at the scratches in Examples 1-3 was only 0.9-1.2 mm, and the blistering, rusting, and cracking levels were all 0. In contrast, the unilateral corrosion spread width at the scratches in Comparative Examples 1-3 increased to 2.4 mm, 2.1 mm, and 3.6 mm, respectively, and blistering of level 1 to 2, rusting of level 1 to 2, and cracking of level 1 in Comparative Example 3 were observed. This indicates that the zinc aluminum phytate silica complex corrosion inhibitor mainly inhibits the corrosion spread of the metal substrate at the scratched area, while the tannin dopamine silica-modified graphene sheet mainly prolongs the penetration path of moisture, oxygen, and corrosive ions. When these two components work together with zinc phosphate, aluminum tripolyphosphate, sericite powder, and hydrophilic fumed silica, a relatively stable interfacial corrosion inhibitor layer and coating shielding structure are formed, thereby solving the problem of insufficient protective durability of existing water-based waterproof and anti-corrosion coatings under long-term immersion and salt spray conditions.

Claims

1. A waterproof and anti-corrosion coating, characterized in that, It includes the following components in parts by weight: The following components are listed: 28-42 parts of waterborne silicone-acrylic emulsion, 12-22 parts of waterborne epoxy-modified acrylic emulsion, 5-12 parts of waterborne polyurethane dispersion, 2-6 parts of zinc aluminum phytate silica-oxygen complex corrosion inhibitor, 0.3-1.2 parts of tannin-dopamine silica-oxygen modified graphene sheets, 3-8 parts of zinc phosphate, 2-6 parts of aluminum tripolyphosphate, 4-10 parts of rutile titanium dioxide, 5-12 parts of sericite powder, and 6-15 parts of precipitated barium sulfate. 3-8 parts talc powder, 0.8-2.5 parts hydrophilic fumed nano silica, 1-3.5 parts waterproofing agent, 0.3-1.0 parts dispersant, 0.1-0.5 parts wetting agent, 0.2-0.8 parts defoamer, 1-3.5 parts film-forming aid, 0.8-2.5 parts propylene glycol, 0.5-2.0 parts polycarbodiimide, 0.2-0.8 parts thickener, and 8-18 parts deionized water.

2. The waterproof and anti-corrosion coating according to claim 1, characterized in that, The preparation method of the zinc aluminum phytate silica complex corrosion inhibitor salt includes: A1. By weight, add 8-15 parts of phytic acid aqueous solution to 35-55 parts of deionized water, stir, add 3-7 parts of zinc oxide and 1-4 parts of aluminum hydroxide, continue stirring, add ammonia water, adjust the pH to 4.5-5.8, and obtain a zinc-aluminum phytate complex dispersion; add 4-8 parts of γ-aminopropyltriethoxysilane to a mixture of 10-18 parts of anhydrous ethanol and 4-10 parts of deionized water, stir, and hydrolyze at 25-35℃ to obtain aminosilane hydrolysate; A2. Under stirring, add the aminosilane hydrolysate to the zinc aluminum phytate complex dispersion, react at 35-45℃, add 0.5-1.5 parts of hydrophilic silica, dry, pulverize, and sieve.

3. The waterproof and anti-corrosion coating according to claim 2, characterized in that, In step A1, the hydrolysis time is 30-60 minutes at 25-35℃.

4. The waterproof and anti-corrosion coating according to claim 2, characterized in that, In step A2, the reaction is carried out at 35-45℃ for 1-3 hours.

5. The waterproof and anti-corrosion coating according to claim 1, characterized in that, The preparation method of the tannin-dopamine-siloxane modified graphene sheet includes: B1. By weight, add 0.8-2.0 parts of graphene oxide to 80-120 parts of deionized water, disperse, add 1-3 parts of tannic acid and 0.3-1.2 parts of dopamine hydrochloride, add ammonia water, adjust the pH to 8.0-8.8, stir and react at 25-35℃ to obtain tannic acid-dopamine modified graphene dispersion; B2. Add 2-5 parts of tetraethyl orthosilicate to 8-15 parts of anhydrous ethanol and mix to obtain a tetraethyl orthosilicate ethanol solution; add the tetraethyl orthosilicate ethanol solution to a tannin-dopamine modified graphene dispersion, add 0.2-0.6 parts of ammonia water, and react at 30-45℃; after the reaction is completed, filter, wash, dry, pulverize, and sieve.

6. The waterproof and anti-corrosion coating according to claim 5, characterized in that, In step B1, the reaction is stirred at 25-35℃ for 2-4 hours.

7. The waterproof and anti-corrosion coating according to claim 5, characterized in that, In step B2, the reaction time is 2-5 hours at 30-45°C.

8. A method for preparing a waterproof and anti-corrosion coating according to any one of claims 1-7, characterized in that, step include: S1. Under stirring, deionized water, dispersant, wetting agent, defoamer and propylene glycol are mixed to obtain an additive dispersion; zinc phosphate, aluminum tripolyphosphate, rutile titanium dioxide, sericite powder, precipitated barium sulfate, talc powder, hydrophilic fumed nano silica, zinc aluminum phytate silica-oxygen complex corrosion inhibitor and tannin dopamine silica-modified graphene sheets are added to the additive dispersion and dispersed to obtain an anti-corrosion and waterproof pigment and filler slurry; S2. Add waterborne silicone-acrylic emulsion, waterborne epoxy-modified acrylic emulsion, and waterborne polyurethane dispersion to the anti-corrosion and waterproof pigment and filler slurry, stir, add waterproofing agent, film-forming aid, defoamer, polycarbodiimide, and thickener, continue stirring, and filter.

9. The method for preparing the waterproof and anti-corrosion coating according to claim 8, characterized in that, In step S1, the dispersant is a sodium salt dispersant of maleic acid-acrylic acid copolymer; the wetting agent is an acetylenic diol polyether wetting agent; and the defoamer is a polyether-modified polydimethylsiloxane defoamer.

10. The method for preparing the waterproof and anti-corrosion coating according to claim 8, characterized in that, In step S2, the waterproofing agent is n-octyltriethoxysilane emulsion waterproofing agent; the film-forming aid is dodecyl alcohol ester film-forming aid; and the thickener is nonionic associative polyurethane thickener.

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