A weather-resistant and corrosion-resistant organic-inorganic composite concrete coating and its preparation method

Abstract

This invention discloses a weather-resistant and corrosion-resistant organic-inorganic composite concrete coating and its preparation method. The coating comprises, by weight, 35-65 parts of functional monomer-modified polyacrylate emulsion, 3-15 parts of composite modified zeolite, 5-25 parts of inorganic shielding filler, 5-30 parts of pigments and fillers, 2-10 parts of additives, and 5-30 parts of deionized water. This invention achieves a multi-faceted synergistic protective effect by combining a core-shell structured acrylate emulsion copolymerized with organosilicon monomers and amide functional monomers with a composite modified zeolite that has undergone acid modification, thermal modification, and silane coupling agent grafting modification. This results in a core-shell structure that balances coating hardness and flexibility, functional monomers imparting hydrophobic self-crosslinking properties, and modified zeolite adsorbing and retaining corrosive ions through a porous framework. This comprehensive improvement in weather resistance, impermeability, and corrosion resistance makes it suitable for long-term surface protection of concrete structures.

Description

Technical Field

[0001] This invention relates to the field of concrete coating technology, and in particular to a weather-resistant and corrosion-resistant organic-inorganic composite concrete coating and its preparation method. Background Technology

[0002] During long-term service, concrete structures are inevitably subjected to multiple factors such as carbonation, chloride and sulfate ion corrosion, ultraviolet radiation, and freeze-thaw cycles, leading to structural performance degradation and shortened service life. Applying protective coatings to the concrete surface is an effective way to delay these deterioration processes. Among them, acrylic emulsion coatings are widely used due to their advantages such as low VOC content, good weather resistance, and convenient application.

[0003] However, conventional acrylic emulsion coatings suffer from insufficient film density, limited water resistance, and weak shielding ability against corrosive media, making it difficult to provide long-term protection for concrete in harsh environments. Among existing modification technologies, organosilicon monomer copolymerization can improve the hydrophobicity and weather resistance of the coating film, but its improvement in resistance to media penetration is limited; core-shell structure design helps to balance film hardness and flexibility, but without a cross-linking mechanism, long-term water resistance and chemical resistance are still insufficient to meet the requirements of highly corrosive conditions; adding inorganic fillers to enhance physical shielding is a common practice, but ordinary inorganic fillers have poor compatibility with organic matrices, are prone to agglomeration and sedimentation, and contribute little to chemical corrosion resistance. None of the above single modification methods can comprehensively solve the problem of synergistic improvement in the coating's weather resistance, impermeability, and corrosion resistance.

[0004] Natural zeolite, due to its porous framework structure and excellent ion exchange adsorption properties, has been widely used in environmental protection and catalysis. Its porous structure's ability to adsorb and retain harmful ions promises to enhance the corrosion resistance of coatings from within. However, natural zeolite has a strong hydrophilic surface and weak interfacial bonding with organic polymer matrices. Direct addition not only makes dispersion difficult but also easily leads to coating defects. Therefore, how to effectively modify natural zeolite to improve its compatibility with organic matrices and synergistically combine it with functional monomer-modified acrylate emulsion systems to achieve a comprehensive improvement in the protective performance of coatings is a technical problem that needs to be solved in this field. Summary of the Invention

[0005] To address the problem that conventional acrylic emulsion coatings in the prior art cannot synergistically improve weather resistance, impermeability, and corrosion resistance, this invention provides a weather-resistant and corrosion-resistant organic-inorganic composite concrete coating and its preparation method.

[0006] The first aspect of the present invention provides a weather-resistant and corrosion-resistant organic-inorganic composite concrete coating, which comprises the following components by weight: 35-65 parts of functional monomer modified polyacrylate emulsion, 3-15 parts of composite modified zeolite, 5-25 parts of inorganic shielding filler, 5-30 parts of pigments and fillers, 2-10 parts of additives and 5-30 parts of deionized water. The latex particles of the functional monomer-modified polyacrylate emulsion have a core-shell structure consisting of a core layer and a shell layer. These latex particles are formed by emulsion copolymerization of a monomer composition comprising hard monomers, soft monomers, carboxyl-containing monomers, organosilicon monomers, and amide functional monomers. Preferably, the glass transition temperature of the core polymer is higher than that of the shell polymer, so that the resulting emulsion balances film strength and flexibility during film formation, further improving the coating's weather resistance, adhesion, and crack resistance. Core-shell emulsion design and room-temperature crosslinked acrylic emulsion systems have been widely used to balance hardness, flexibility, and film-forming properties.

[0007] Preferably, by weight, the monomer composition comprises 25-40 parts of hard monomer, 40-70 parts of soft monomer, 1-5 parts of carboxyl-containing monomer, 1-6 parts of organosilicon monomer, and 1.5-6 parts of amide functional monomer.

[0008] Preferably, the hard monomer is selected from one or two of methyl methacrylate and isoborneol methacrylate; the soft monomer is selected from one or two of butyl acrylate and 2-ethylhexyl acrylate; the carboxyl-containing monomer is selected from one or two of acrylic acid and methacrylic acid; the organosilicon monomer is selected from one or two of vinyltriethoxysilane and γ-methacryloyloxypropyltrimethoxysilane; and the amide functional monomer is preferably N-hydroxymethylacrylamide. Preferably, the amide functional monomer participates in emulsion polymerization and helps to improve the density, water resistance, and chemical resistance of the coating film during film drying and subsequent curing and / or heating processes.

[0009] Preferably, the glass transition temperature of the core layer is 50–90°C, the glass transition temperature of the shell layer is -15–10°C, and the core layer accounts for 30–60% of the total mass of the latex particle polymer, with the shell layer making up the remainder. By controlling the glass transition temperatures and their proportional relationship between the core and shell layers, the resulting emulsion can achieve a balance between hardness and flexibility during film formation, thereby reducing coating brittleness, improving adhesion, and enhancing overall durability under outdoor service conditions.

[0010] The composite modified zeolite is a modified zeolite obtained by acid modification, thermal modification, and surface grafting modification with a silane coupling agent from natural zeolite. Preferably, the natural zeolite is selected from one or two of natural clinoptilolite and natural mordenite. Acid and thermal modification of the natural zeolite can adjust its surface state and pore structure; further surface grafting modification with a silane coupling agent can improve its compatibility and interfacial bonding with the organic emulsion matrix, thereby improving its dispersion stability in the coating system, reducing particle agglomeration and interfacial defects, and contributing to improved overall coating density and long-term protective performance. Zeolite-based functional fillers already have a basis for application in barrier, protective, and adsorption materials.

[0011] Preferably, the inorganic shielding filler is selected from one or more of mica powder, sericite powder, talc powder, calcined kaolin, and glass flakes; the pigments and fillers are selected from one or more of titanium dioxide, heavy calcium carbonate, barium sulfate, and quartz powder. The inorganic shielding filler is used to extend the diffusion path of corrosive media in the coating and enhance the physical shielding effect of the coating; the pigments and fillers are used to improve hiding power, filling properties, and workability, and help to adjust the mechanical properties and volume stability of the coating.

[0012] Preferably, the additives include 0.5-1.5 parts of dispersant, 0.2-0.8 parts of wetting agent, 0.1-0.6 parts of defoamer, 0.8-5.0 parts of film-forming aid, 0.3-1.3 parts of thickener, and 0.1-0.8 parts of paint pH adjuster. Dispersants are used to ensure the uniform dispersion and stability of pigments, fillers, and functional fillers in the coating system; sodium polycarboxylate or polyphosphate dispersants can be selected. Wetting agents are used to reduce the surface tension of the coating, improve the wettability of pigments and fillers, and enhance the wetting and spreading properties of the coating on the substrate; silicone or acetylenic diol wetting agents can be selected. Defoamers are used to eliminate bubbles generated during the preparation and application of the coating; mineral oil or silicone defoamers can be selected. Film-forming aids are used to temporarily lower the minimum film-forming temperature of the polymer during film formation, promoting the full deformation and fusion of latex particles; dodecyl alcohol esters, dipropylene glycol butyl ether, etc., can be selected. Thickeners are used to adjust the rheological properties of the coating, giving it suitable application viscosity and anti-sagging properties; cellulose ether or associative polyurethane thickeners can be selected. pH adjusters are used to adjust the pH value of the coating system to a suitable range, ensuring the storage stability of the coating; ammonia or 2-amino-2-methyl-1-propanol can be selected.

[0013] A second aspect of the present invention provides a method for preparing the above-mentioned weather-resistant and corrosion-resistant organic-inorganic composite concrete coating, comprising the following steps: S1. Natural zeolite is pulverized to 200–400 mesh, dried, and then acid-modified using a 0.3–0.8 mol / L hydrochloric acid solution at 40–60°C for 1–3 h. After treatment, it is filtered, washed until neutral, and dried. Then, it is thermally modified at 450–550°C for 1–3 h. Finally, it is surface-grafted with silane coupling agent in an ethanol-water mixed solvent with a volume fraction of 70–95% and a pH of 4–6. The amount of silane coupling agent is 1–5% of the zeolite mass. The treatment is carried out at 50–70°C for 1–4 h. After grafting modification, it is filtered, dried, and pulverized to obtain composite modified zeolite.

[0014] Preferably, in step S1, the natural zeolite is pulverized and dried at 80–120°C for 1–4 h; during acid modification, the solid-liquid mass ratio of the natural zeolite to the hydrochloric acid solution is 1:5–1:10; the silane coupling agent is selected from one or both of γ-aminopropyltriethoxysilane and γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and after graft modification, it is dried at 80–100°C for 2–6 h.

[0015] S2, under nitrogen protection, hard monomers, soft monomers, carboxyl-containing monomers, organosilicon monomers, and amide functional monomers are formulated into core-layer pre-emulsions and shell-layer pre-emulsions according to the core-shell design ratio. In the presence of emulsifiers, initiators, and buffers, a semi-continuous seed emulsion polymerization method is adopted. Core-layer polymerization is carried out first at 75-85℃, followed by shell-layer polymerization. After cooling, the pH of the emulsion is adjusted to 7-9 to obtain functional monomer-modified polyacrylate emulsion.

[0016] Preferably, in step S2, the total amount of emulsifier is 1.0% to 4.0% of the total monomer mass, the amount of initiator is 0.2% to 0.8% of the total monomer mass, and the amount of buffer is 0.05% to 0.3% of the total monomer mass. The emulsifier is a mixture of anionic and nonionic emulsifiers; preferably, the emulsifier is selected from sodium dodecyl sulfate and nonylphenol polyoxyethylene ether. The initiator is ammonium persulfate and / or potassium persulfate, and the buffer is sodium bicarbonate.

[0017] Further, in step S2, 5%–20% of the total amount of core layer preemulsion and 10%–30% of the total amount of initiator solution are first added to the reaction vessel, and the seed emulsion is formed at 75–85°C. Then, the remaining core layer preemulsion and 20%–40% of the total amount of initiator solution are added dropwise simultaneously over 1–2 hours, and the temperature is maintained for 0.5–1 hour after the addition is completed. Then, the shell layer preemulsion and the remaining initiator solution are added dropwise simultaneously over 1.5–3 hours, and the temperature is maintained for 0.5–2 hours after the addition is completed. After cooling, one or both of ammonia and 2-amino-2-methyl-1-propanol are used as emulsion neutralizers to adjust the pH to 7–9, and the emulsion is obtained by filtration.

[0018] S3. After uniformly mixing deionized water, dispersant, wetting agent and defoamer at 300-800 r / min, add the composite modified zeolite, inorganic shielding filler and pigments, disperse at 800-1500 r / min for 15-40 min and grind to a fineness of no more than 60 μm; then add the functional monomer modified polyacrylate emulsion, film-forming aid, thickener and paint pH adjuster to adjust the paint for 10-30 min, and filter through 100-200 mesh to obtain the finished product.

[0019] Step S3 employs a two-stage process: grinding followed by paint mixing. In the grinding stage, pigments, fillers, and functional fillers are dispersed and ground to the target fineness at high speeds, ensuring thorough wetting and depolymerization in the aqueous phase. In the paint mixing stage, emulsions and additives are added under lower shear conditions to avoid the demulsifying effect of high shear on the emulsion. The grinding fineness is controlled to no more than 60 μm to guarantee the smoothness and appearance quality of the coating film. The filtration step removes any coarse particles and impurities that may be present in the coating, ensuring its application performance.

[0020] Compared with the prior art, the present invention provides a weather-resistant and corrosion-resistant organic-inorganic composite concrete coating and its preparation method, which has the following beneficial effects: 1. This invention combines a core-shell structured acrylic emulsion modified with functional monomers with composite modified zeolite in an organic-inorganic composite process. The core-shell structure design balances the hardness and flexibility of the coating film. The copolymerization of organosilicon monomers imparts hydrophobicity and weather resistance to the coating film. The self-crosslinking effect of amide functional monomers enhances the density and water resistance of the coating film. The composite modified zeolite strengthens the anti-corrosion performance of the coating from the inside through the adsorption and retention of corrosive ions by the porous framework. The synergistic effect of multiple mechanisms enables the coating to achieve a comprehensive improvement in weather resistance, impermeability and corrosion resistance.

[0021] 2. This invention involves a three-step composite modification treatment of natural zeolite, namely acid modification, thermal modification, and silane coupling agent surface grafting modification. Acid modification opens up the pores and increases the specific surface area, thermal modification stabilizes the skeleton structure, and silane coupling agent grafting constructs an organic-inorganic transition layer on the zeolite surface. This allows the modified zeolite to retain its ability to adsorb and retain harmful ions while also having good interfacial compatibility with organic polymer matrices, thus solving the problems of difficult dispersion and weak interfacial bonding of natural zeolite in organic coating systems.

[0022] 3. The preparation method of the present invention is simple. It uses semi-continuous seed emulsion polymerization to prepare core-shell emulsion and a two-stage process of grinding and then mixing to prepare coating. The conditions of each step are mild and easy to scale up for industrial production. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only 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.

[0024] The raw materials used in the following examples and comparative examples are all commercially available products, including: methyl methacrylate (MMA), butyl acrylate (BA), 2-ethylhexyl acrylate (2-EHA), methacrylic acid (MAA), acrylic acid (AA), and isoborneol methacrylate (IBOMA) are all of analytical grade; γ-methacryloyloxypropyltrimethoxysilane (KH-570), vinyltriethoxysilane (A-151), γ-aminopropyltriethoxysilane (KH-550), and γ-(2,3-epoxypropoxy) Propyltrimethoxysilane (KH-560) was industrial grade; N-hydroxymethylacrylamide (NMA) was industrial grade; natural clinoptilolite and natural mordenite were purchased from a mining company in Hebei Province, with a particle size of 200-400 mesh; sodium dodecyl sulfate (SDS), nonylphenol polyoxyethylene ether (OP-10), ammonium persulfate (APS), and sodium bicarbonate were all analytical grade; titanium dioxide was R-996 type rutile titanium dioxide; mica powder was 800 mesh wet-process mica powder; heavy calcium carbonate was 1250 mesh; and calcined kaolin was 4000 mesh. Example 1

[0025] This embodiment provides a weather-resistant and corrosion-resistant organic-inorganic composite concrete coating, which is prepared according to the following steps: S1, Preparation of composite modified zeolite: Natural clinoptilolite was pulverized to 300 mesh and dried at 100℃ for 2 h. The dried zeolite was mixed with a 0.5 mol / L hydrochloric acid solution at a solid-liquid mass ratio of 1:8 and stirred at 50℃ for 2 h. The mixture was then filtered, washed with deionized water until the pH of the filtrate was neutral, and dried at 100℃ for 2 h. The acid-modified zeolite was then placed in a muffle furnace and heat-treated at 500℃ for 2 h, followed by natural cooling to room temperature.

[0026] Prepare an ethanol-water mixed solvent with an ethanol volume fraction of 85%, and adjust the pH to 5 with acetic acid. Add the thermally modified zeolite to the above mixed solvent, add 3% KH-550 by weight of the zeolite, stir at 60℃ for 2 h, filter, dry at 90℃ for 4 h, grind and sieve to 300 mesh to obtain the composite modified zeolite.

[0027] S2, Preparation of functional monomer-modified polyacrylate emulsion: Monomer composition formulation (by weight parts): 33 parts hard monomer (25 parts MMA, 8 parts IBOMA), 55 parts soft monomer (40 parts BA, 15 parts 2-EHA), 3 parts carboxyl-containing monomer (2 parts MAA, 1 part AA), 4 parts organosilicon monomer (3 parts KH-570, 1 part A-151), and 5 parts amide functional monomer (NMA).

[0028] Core layer monomer composition: 25 parts MMA, 8 parts IBOMA, 5 parts BA, 1 part MAA, 1 part KH-570, totaling 40 parts (accounting for 40% of the total monomers). The core layer design Tg is approximately 70℃.

[0029] Shell monomer composition: BA 35 parts, 2-EHA 15 parts, MAA 1 part, AA 1 part, KH-570 2 parts, A-151 1 part, NMA 5 parts, totaling 60 parts (accounting for 60% of the total monomers). The shell design Tg is approximately -5℃.

[0030] The total amount of emulsifier is 2.5% of the total monomer mass (SDS 1.5%, OP-10 1.0%), the amount of initiator (APS) is 0.5% of the total monomer mass, and the amount of buffer (sodium bicarbonate) is 0.15% of the total monomer mass.

[0031] The core monomer and shell monomer were respectively mixed with the corresponding proportions of emulsifier aqueous solution, and pre-emulsified by high-speed stirring for 30 min to obtain core pre-emulsion and shell pre-emulsion, respectively. The initiator was dissolved in deionized water to prepare an initiator solution.

[0032] In a four-necked flask equipped with a stirrer, thermometer, reflux condenser, and dropping funnel, deionized water and buffer were added, and nitrogen gas was purged for oxygen removal for 30 min. The temperature was then raised to 80°C. 10% of the total core-layer preemulsion and 20% of the total initiator solution were added to the flask, and the mixture was reacted at 80°C for 20 min to form a seed emulsion. The remaining core-layer preemulsion and 30% of the total initiator solution were then added dropwise simultaneously over 1.5 h, and the mixture was kept at this temperature for 0.5 h after the addition was complete. Subsequently, the shell-layer preemulsion and the remaining initiator solution were added dropwise simultaneously over 2 h, and the mixture was kept at this temperature for 1 h after the addition was complete. The mixture was cooled to below 40°C, the pH was adjusted to 8.0 with ammonia, and the emulsion was filtered through a 200-mesh screen to obtain a functional monomer-modified polyacrylate emulsion.

[0033] The resulting emulsion had a solid content of 48% and an average particle size of approximately 150 nm.

[0034] S3, Preparation of coating: The coating formulation, by weight, is as follows: 50 parts functional monomer modified polyacrylate emulsion, 9 parts composite modified zeolite, 15 parts inorganic shielding filler (10 parts mica powder, 5 parts calcined kaolin), 18 parts pigments and fillers (10 parts titanium dioxide, 8 parts heavy calcium carbonate), 6 parts additives (1.0 part dispersant, 0.5 part wetting agent, 0.3 part defoamer, 3.0 part film-forming aid, 0.8 part thickener, 0.4 part paint pH adjuster, wherein the dispersant is a sodium polycarboxylate dispersant, the wetting agent is an acetylenic diol wetting agent, the defoamer is a mineral oil defoamer, the film-forming aid is dodecyl alcohol ester, the thickener is an associative polyurethane thickener, and the paint pH adjuster is 2-amino-2-methyl-1-propanol), and 15 parts deionized water.

[0035] Deionized water, dispersant, wetting agent, and defoamer were added to a dispersion tank and mixed evenly at 500 r / min. Then, composite modified zeolite, mica powder, calcined kaolin, titanium dioxide, and heavy calcium carbonate were added and dispersed at 1200 r / min for 30 min. The mixture was then ground to a fineness of no more than 50 μm. Subsequently, functional monomer-modified polyacrylate emulsion, film-forming aid, thickener, and paint pH adjuster were added and mixed at 500 r / min for 20 min. The mixture was then filtered through a 150-mesh filter to obtain the finished coating. Example 2

[0036] The difference between this embodiment and Embodiment 1 is that: In S1, the natural zeolite is natural mordenite, pulverized to 200 mesh, and dried at 80℃ for 4 h; the hydrochloric acid concentration is 0.3 mol / L, the solid-liquid mass ratio is 1:5, and it is treated at 40℃ for 3 h; the heat modification temperature is 450℃, and it is treated for 3 h; the silane coupling agent is KH-560, the amount is 1% of the zeolite mass, the volume fraction of ethanol in the ethanol-water mixed solvent is 70%, the pH of the mixed solvent is 4, and it is treated at 50℃ for 4 h; after grafting, it is dried at 80℃ for 6 h, ground and sieved to 200 mesh.

[0037] In S2, the monomer composition formulation (by weight parts) is as follows: 25 parts hard monomer (17 parts IBOMA, 8 parts MMA), 70 parts soft monomer (55 parts BA, 15 parts 2-EHA), 1 part carboxyl-containing monomer (1 part AA), 2 parts organosilicon monomer (2 parts KH-570), and 6 parts amide functional monomer (NMA).

[0038] The core layer monomers account for 30% of the total monomers, with a designed Tg of approximately 55℃. The shell layer monomers account for 70% of the total monomers, with a designed Tg of approximately -15℃.

[0039] The total amount of emulsifier was 1% of the total monomer mass, the amount of initiator was 0.2% of the total monomer mass, and the amount of buffer was 0.08% of the total monomer mass. The polymerization temperature was 75℃. In the seed stage, 5% of the total core layer pre-emulsion and 10% of the total initiator were used. In the core layer dropping stage, the initiator amount was 20% of the total, the core layer dropping time was 1 h, and the shell layer dropping time was 1.5 h. After cooling, the pH was adjusted to 7.5 with ammonia.

[0040] The resulting emulsion had a solid content of 42% and an average particle size of approximately 200 nm.

[0041] In S3, the coating formulation consists of: 35 parts of functional monomer modified polyacrylate emulsion, 3 parts of composite modified zeolite, 5 parts of inorganic shielding filler (5 parts of mica powder), 5 parts of pigments and fillers (3 parts of titanium dioxide and 2 parts of heavy calcium carbonate), 2 parts of additives (0.5 parts of dispersant, 0.2 parts of wetting agent, 0.1 parts of defoamer, 0.8 parts of film-forming aid, 0.3 parts of thickener, and 0.1 parts of paint pH adjuster, wherein the film-forming aid is dipropylene glycol butyl ether, the thickener is a cellulose ether thickener, and the paint pH adjuster is ammonia water), and 5 parts of deionized water.

[0042] Mixing speed 400 r / min, dispersion speed 800 r / min, dispersion time 15 min, grinding fineness no greater than 60 μm, paint mixing time 10 min, and filtering through a 100-mesh filter. Example 3

[0043] The difference between this embodiment and Embodiment 1 is that: In S1, the natural zeolite is a 1:1 mass ratio mixture of natural clinoptilolite and natural mordenite, pulverized to 400 mesh, and dried at 120℃ for 1 h; the hydrochloric acid concentration is 0.8 mol / L, the solid-liquid mass ratio is 1:10, and it is treated at 60℃ for 1 h; the heat modification temperature is 550℃, and it is treated for 1 h; the silane coupling agent is a 1:1 mass ratio mixture of KH-550 and KH-560, with a total amount of 5% of the zeolite mass; the ethanol-water mixed solvent has an ethanol volume fraction of 95% and a pH of 6, and is treated at 70℃ for 1 h; after grafting, it is dried at 100℃ for 2 h, ground, and sieved to 400 mesh.

[0044] In S2, the monomer composition formulation (by weight parts) is as follows: 40 parts hard monomer (30 parts MMA, 10 parts IBOMA), 42 parts soft monomer (29 parts BA, 13 parts 2-EHA), 5 parts carboxyl-containing monomer (3 parts MAA, 2 parts AA), 6 parts organosilicon monomer (4 parts KH-570, 2 parts A-151), and 1.5 parts amide functional monomer (NMA).

[0045] The core layer monomers account for 58% of the total monomers, with a designed Tg of approximately 85℃. The shell layer monomers account for 42% of the total monomers, with a designed Tg of approximately 8℃.

[0046] The total amount of emulsifier was 4.0% of the total monomer mass, the amount of initiator was 0.8% of the total monomer mass, and the amount of buffer was 0.3% of the total monomer mass. The polymerization temperature was 85℃. In the seed stage, 20% of the total core layer pre-emulsion and 30% of the total initiator were used. In the core layer dropping stage, the initiator amount was 40% of the total, the core layer dropping time was 2 h, and the shell layer dropping time was 3 h. After cooling, the pH was adjusted to 9.0 with 2-amino-2-methyl-1-propanol.

[0047] The resulting emulsion had a solid content of 53% and an average particle size of approximately 100 nm.

[0048] In S3, the coating formulation consists of: 65 parts of functional monomer modified polyacrylate emulsion, 15 parts of composite modified zeolite, 25 parts of inorganic shielding filler (12 parts of mica powder, 5 parts of sericite powder, and 8 parts of glass flakes), 30 parts of pigments and fillers (15 parts of titanium dioxide, 10 parts of heavy calcium carbonate, and 5 parts of barium sulfate), 10 parts of additives (1.5 parts of dispersant, 0.8 parts of wetting agent, 0.6 parts of defoamer, 5.0 parts of film-forming aid, 1.3 parts of thickener, and 0.8 parts of paint pH adjuster), and 30 parts of deionized water.

[0049] Mixing speed 800 r / min, dispersion speed 1500 r / min, dispersion time 40 min, grinding fineness no greater than 40 μm, paint mixing time 30 min, and filtering through a 200 mesh filter. Example 4

[0050] The difference from Example 1 is that in S2, the amount of organosilicon monomer used is 1 part (1 part KH-570), while the amounts of other monomers remain unchanged. The core layer is designed with a Tg of approximately 70°C, and the shell layer is designed with a Tg of approximately -7°C. All other conditions are the same as in Example 1. Comparative Example 1

[0051] The difference between this comparative example and Example 1 is that no composite modified zeolite is added, the amount of composite modified zeolite in the coating formulation is 0 parts, and the amount of deionized water is increased accordingly to keep the total amount of coating unchanged. All other conditions are exactly the same as in Example 1. Comparative Example 2

[0052] The difference between this comparative example and Example 1 is that the natural zeolite in S1 is not modified in any way; natural clinoptilolite, crushed to 300 mesh, is used directly as a filler. All other conditions are exactly the same as in Example 1. Comparative Example 3

[0053] The difference between this comparative example and Example 1 is that in S1, the natural zeolite undergoes acid and thermal modification treatments, but not silane coupling agent grafting modification. That is, after thermal modification, it is directly ground and sieved to 300 mesh for use as modified zeolite. All other conditions are exactly the same as in Example 1. Comparative Example 4

[0054] The difference between this comparative example and Example 1 is that the emulsion in S2 uses conventional one-step emulsion polymerization and does not employ a core-shell structure design. All monomers (33 parts hard monomer, 55 parts soft monomer, 3 parts carboxyl-containing monomer, 4 parts organosilicon monomer, and 5 parts amide functional monomer) are mixed to prepare a pre-emulsion, which is then added dropwise at 80°C for 3 hours, followed by a 1-hour holding time. All other conditions are identical to those in Example 1. Comparative Example 5

[0055] The difference between this comparative example and Example 1 is that the monomer composition in S2 does not contain organosilicon monomers. The original 4 parts of organosilicon monomers were made up by an equal amount of butyl acrylate. The monomer composition formulation was adjusted to: 33 parts of hard monomers (25 parts of MMA, 8 parts of IBOMA), 59 parts of soft monomers (44 parts of BA, 15 parts of 2-EHA), 3 parts of carboxyl-containing monomers (2 parts of MAA, 1 part of AA), and 5 parts of amide functional monomers (NMA), with the total monomer amount remaining unchanged at 100 parts. The core-shell ratio is the same as in Example 1. The shell design Tg is slightly lower due to the slightly increased proportion of BA, but the deviation is limited (approximately 2-3 °C) and does not affect the validity of the comparative analysis. All other conditions are exactly the same as in Example 1.

[0056] Comparative Example 6 The difference between this comparative example and Example 1 is as follows: In S2, the monomer composition does not contain the amide functional monomer NMA, and the original 5 parts of NMA are supplemented with an equal amount of butyl acrylate. The monomer composition formula is adjusted to: 33 parts of hard monomers (25 parts of MMA, 8 parts of IBOMA), 60 parts of soft monomers (45 parts of BA, 15 parts of 2-EHA), 3 parts of carboxyl-containing monomers (2 parts of MAA, 1 part of AA), 4 parts of organosilicon monomers (3 parts of KH-570, 1 part of A-151), and the total amount of monomers remains unchanged at 100 parts. The core-shell ratio is the same as that in Example 1. The designed Tg of the shell layer decreases slightly due to the slightly increased proportion of BA, but the deviation range is limited (about 3 - 4 °C), which does not affect the validity of the comparative analysis. The remaining conditions are exactly the same as those in Example 1. Performance Testing

[0057] The coatings prepared in the examples and comparative examples were respectively coated on the surface of polished and cleaned C30 concrete test blocks, coated in two layers, with a dry film thickness of about 60 μm for each layer and a total dry film thickness of about 120 μm. After curing for 7 d under standard conditions (temperature 23 ± 2 °C, relative humidity 50 ± 5%), performance testing was carried out.

[0058] The test items and methods are as follows: (1) Adhesion: Tested according to GB / T 5210-2006 "Paints and varnishes - Pull-off adhesion test", and the pull-off strength (MPa) was recorded.

[0059] (2) Water resistance: Referring to the water resistance test method in GB / T 9755-2024, the coated test panels were immersed in deionized water at (23 ± 2) °C, and the appearance changes of the coating films were observed when taken out at 96 h and 720 h respectively. 96 h is the standard evaluation node, and 720 h is the more stringent evaluation node.

[0060] (3) Resistance to artificial aging: Tested according to GB / T 1865-2009 "Paints and varnishes - Artificial weathering and exposure to artificial radiation - Filtered xenon-arc radiation", after 1000 h of xenon lamp aging, the powdering grade and discoloration grade of the coating film were evaluated according to GB / T 1766-2008 "Paints and varnishes - Rating schemes for degradation of coatings". The powdering grade of 0 is the best, and the discoloration grade of 0 is the best.

[0061] (4) Chloride ion penetration resistance: The natural diffusion method was used for testing. The uncoated surface and four sides of the coated concrete specimen (100mm × 100mm × 50mm) were sealed with epoxy resin, leaving only the coated surface exposed. The specimen was then immersed in a 3.5% NaCl solution with the coated surface facing down for 60 days, with the solution level approximately 5mm above the coated surface. After immersion, the specimen was removed, and powder was collected by grinding each layer every 5mm along the thickness direction from the coated surface. The free chloride ion content of each layer was determined by silver nitrate titration according to JTG 3420-2020 "Test Procedures for Cement and Cement Concrete in Highway Engineering". The chloride ion content (percentage of concrete mass, %) at a depth of 10mm below the coated surface was used as the evaluation index. The lower the value, the stronger the barrier ability of the coating against chloride ions. A blank uncoated concrete specimen was used as a baseline control.

[0062] (5) Alkali resistance: The test was conducted according to GB / T 9265-2009 "Determination of alkali resistance of building coatings". The coated test panel was immersed in saturated Ca(OH)2 solution for 48 h and the changes in the appearance of the coating were observed.

[0063] (6) Water absorption: The coated concrete specimen (100 mm × 100 mm × 50 mm, with the uncoated side and all four sides sealed with epoxy resin) was floated on the water surface with the coated side facing down, in contact with the water surface. It was placed under standard conditions (temperature 23±2℃, relative humidity 50±5%) for 24 h, and the water absorption was calculated using the following formula: W = (m1-m0) / A In the formula: W is the water absorption (g / m³) 2 m1 is the mass of the test block after soaking (g); m0 is the mass of the test block before soaking (g); A is the area of ​​the coated surface (m²). 2 The lower the water absorption, the better the coating's impermeability. Test Results

[0064] Table 1. Performance test results of the examples and comparative examples: .

[0065] Note: After immersion under the same conditions for 60 days, the chloride ion content at a depth of 10 mm in blank concrete test blocks without coating was 0.085%, and the water absorption was 120 g / m³. 2 .

[0066] Results Analysis Example 1 exhibits the best overall performance, with a chloride ion content of only 0.012% (approximately 85.9% lower than the blank control of 0.085%) and a water absorption capacity of 30 g / m³. 2The water resistance remained unchanged after 720 hours, and the adhesion was 3.2 MPa. Example 2, representing the lower limit endpoint, showed slight whitening after 720 hours of water resistance and a water absorption of 53 g / m³. 2 The chloride ion content was 0.022%, and all indicators were still better than all comparative examples, indicating that the lower limit scheme was feasible. Example 3 was the upper limit scheme, with good performance and better than Example 2. Example 4 verified the scheme with low dosage of organosilicon monomer (1 part), and the water absorption increased to 45 g / m³. 2 Although the hydrophobicity decreased, the overall performance was still significantly better than that of each pair.

[0067] Comparative Example 1, without the addition of composite modified zeolite, showed an increase in chloride ion content to 0.058% and water absorption to 85 g / m³. 2 Slight whitening was observed in the alkali resistance of the first example, indicating that the composite modified zeolite is a key component for its anti-permeability and anti-corrosion properties. Comparative Example 2, using unmodified natural zeolite, showed an adhesion strength of only 2.0 MPa and whitening after 96 hours of water resistance, with both chalking and discoloration grades deteriorating. This indicates poor compatibility between the unmodified zeolite and the organic matrix, creating a weak point in its penetration. Comparative Example 3, lacking the silane grafting step, saw its water absorption increase to 59 g / m³. 2 The chloride ion content was 0.030%, indicating that silane grafting was indispensable in the three-step composite modification.

[0068] Comparative Example 4, using a one-step method to replace the core-shell structure, showed whitening after 96 hours of water resistance, a chalking grade that degraded to level 1, a chloride ion content that increased to 0.042%, and a water absorption of 68 g / m³. 2 This indicates that the core-shell structure is crucial for improving the overall performance of the coating. Comparative Example 5, lacking organosilicon monomers, showed a significant decrease in water resistance and a substantial increase in water absorption to 65 g / m³. 2 The discoloration level degraded to level 2, indicating that the hydrophobic properties imparted by the organosilicon copolymerization contributed significantly. Comparative Example 6, which did not contain NMA, showed obvious whitening after 720 hours of water resistance, with water absorption increasing to 60 g / m³. 2 The chloride ion content rose to 0.025%, indicating that the self-crosslinking effect of NMA is irreplaceable for the coating's density and water resistance.

[0069] 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 weather-resistant and corrosion-resistant organic-inorganic composite concrete coating, characterized in that, By weight, it includes the following components: 35-65 parts of functional monomer modified polyacrylate emulsion, 3-15 parts of composite modified zeolite, 5-25 parts of inorganic shielding filler, 5-30 parts of pigments and fillers, 2-10 parts of additives and 5-30 parts of deionized water. The latex particles of the functional monomer modified polyacrylate emulsion have a core-shell structure consisting of a core layer and a shell layer. The latex particles are formed by emulsion copolymerization of a monomer composition containing hard monomers, soft monomers, carboxyl-containing monomers, organosilicon monomers and amide functional monomers. The composite modified zeolite is a modified zeolite obtained by acid modification, thermal modification and surface grafting modification with silane coupling agent from natural zeolite.

2. The weather-resistant and corrosion-resistant organic-inorganic composite concrete coating according to claim 1, characterized in that, By weight, the monomer composition comprises 25-40 parts of hard monomer, 40-70 parts of soft monomer, 1-5 parts of carboxyl-containing monomer, 1-6 parts of organosilicon monomer, and 1.5-6 parts of amide functional monomer.

3. The weather-resistant and corrosion-resistant organic-inorganic composite concrete coating according to claim 2, characterized in that, The hard monomer is selected from one or two of methyl methacrylate and isoborneol methacrylate; the soft monomer is selected from one or two of butyl acrylate and 2-ethylhexyl acrylate; the carboxyl-containing monomer is selected from one or two of acrylic acid and methacrylic acid; the organosilicon monomer is selected from one or two of vinyltriethoxysilane and γ-methacryloyloxypropyltrimethoxysilane; and the amide functional monomer is N-hydroxymethylacrylamide.

4. The weather-resistant and corrosion-resistant organic-inorganic composite concrete coating according to claim 1, characterized in that, The glass transition temperature of the core layer is 50–90°C, the glass transition temperature of the shell layer is -15–10°C, and the core layer accounts for 30–60% of the total mass of the latex particle polymer, with the shell layer being the remainder.

5. The weather-resistant and corrosion-resistant organic-inorganic composite concrete coating according to claim 1, characterized in that, The natural zeolite is selected from one or two of natural clinoptilolite and natural mordenite.

6. The weather-resistant and corrosion-resistant organic-inorganic composite concrete coating according to claim 1, characterized in that, The inorganic shielding filler is selected from one or more of mica powder, sericite powder, talc powder, calcined kaolin, and glass flakes; the pigments and fillers are selected from one or more of titanium dioxide, heavy calcium carbonate, barium sulfate, and quartz powder. The additives include 0.5-1.5 parts of dispersant, 0.2-0.8 parts of wetting agent, 0.1-0.6 parts of defoamer, 0.8-5.0 parts of film-forming aid, 0.3-1.3 parts of thickener, and 0.1-0.8 parts of paint pH adjuster.

7. A method for preparing a weather-resistant and corrosion-resistant organic-inorganic composite concrete coating as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Natural zeolite is pulverized to 200-400 mesh, dried, and then acid-modified using a 0.3-0.8 mol / L hydrochloric acid solution at 40-60℃ for 1-3 h. After treatment, it is filtered, washed until neutral, and dried. Then, it is thermally modified at 450-550℃ for 1-3 h. Finally, it is surface-grafted with silane coupling agent in an ethanol-water mixed solvent with a volume fraction of 70-95% and a pH of 4-6. The amount of silane coupling agent is 1-5% of the zeolite mass. The treatment is carried out at 50-70℃ for 1-4 h. After grafting modification, it is filtered, dried, and pulverized to obtain composite modified zeolite. S2, under nitrogen protection, hard monomers, soft monomers, carboxyl-containing monomers, organosilicon monomers and amide functional monomers are respectively formulated into core layer preemulsions and shell layer preemulsions. In the presence of emulsifiers, initiators and buffers, semi-continuous seed emulsion polymerization is carried out. Core layer polymerization is carried out first at 75-85℃, followed by shell layer polymerization. After cooling, the pH of the emulsion is adjusted to 7-9 to obtain functional monomer modified polyacrylate emulsion. S3. After uniformly mixing deionized water, dispersant, wetting agent and defoamer at 300-800 r / min, add the composite modified zeolite, inorganic shielding filler and pigments, disperse at 800-1500 r / min for 15-40 min and grind to a fineness of no more than 60 μm; then add the functional monomer modified polyacrylate emulsion, film-forming aid, thickener and paint pH adjuster to adjust the paint for 10-30 min, and filter through 100-200 mesh to obtain the finished product.

8. The preparation method according to claim 7, characterized in that, In step S1, the natural zeolite is pulverized and dried at 80–120°C for 1–4 h; during acid modification, the solid-liquid mass ratio of the natural zeolite to the hydrochloric acid solution is 1:5–1:10; the silane coupling agent is selected from one or both of γ-aminopropyltriethoxysilane and γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and after graft modification, it is dried at 80–100°C for 2–6 h.

9. The preparation method according to claim 7, characterized in that, In step S2, the total amount of emulsifier is 1.0-4.0% of the total mass of monomers, the amount of initiator is 0.2-0.8% of the total mass of monomers, and the amount of buffer is 0.05-0.3% of the total mass of monomers; the emulsifier is a compound of anionic and nonionic emulsifiers, the initiator is ammonium persulfate and / or potassium persulfate, and the buffer is sodium bicarbonate.

10. The preparation method according to claim 9, characterized in that, In step S2, 5-20% of the total amount of core layer preemulsion and 10-30% of the total amount of initiator solution are added to the reaction vessel and initiated at 75-85°C to form a seed emulsion. Then, the remaining core layer preemulsion and 20-40% of the total amount of initiator solution are added dropwise over 1-2 hours, and the mixture is kept warm for 0.5-1 hours after the addition is completed. Then, the shell layer preemulsion and the remaining initiator solution are added dropwise over 1.5-3 hours, and the mixture is kept warm for 0.5-2 hours after the addition is completed. After cooling, one or both of ammonia and 2-amino-2-methyl-1-propanol are used as emulsion neutralizers to adjust the pH to 7-9, and the mixture is filtered to obtain the functional monomer modified polyacrylate emulsion.