Building environment-friendly water-based paint and processing method thereof

Abstract

The invention provides an environment-friendly water-based paint for buildings and a processing method thereof. The environment-friendly water-based paint comprises the following components: 40-60 parts of an elastic grafted hydrophobic emulsion, 5-10 parts of a low-temperature activated cross-linking agent, 3-8 parts of corrosion inhibitor microcapsules, 15-25 parts of pigments and fillers, 1-3 parts of a dispersing agent, 0.5-2 parts of a wetting agent, 0.3-1 part of a defoaming agent, 0.5-2 parts of a thickening agent, 1-4 parts of a coalescing agent and 10-20 parts of deionized water. The low-temperature activated modified isocyanate cross-linking agent is adopted, the activation temperature is low, rapid cross-linking curing can be achieved at the temperature of about 5 DEG C, the film forming time is greatly shortened, meanwhile, the modified cross-linking agent is good in compatibility with elastic grafted hydrophobic emulsion, the cross-linking density of a coating is improved, the adhesive force of the coating and a base material reaches the first level, and the coating is not prone to falling off. The coating is prevented from falling off and cracking in a low-temperature and high-humidity environment

Description

Technical Field

[0001] This invention relates to the field of architectural coatings technology, and in particular to an environmentally friendly water-based coating for building and its processing method. Background Technology

[0002] With tightening environmental policies and the popularization of green building concepts, architectural coatings are gradually shifting from solvent-based to water-based. Environmentally friendly water-based coatings, due to their advantages such as no volatile organic solvent pollution and friendliness to humans and the environment, have been widely used for interior and exterior wall decoration and protection in various buildings. However, existing environmentally friendly water-based architectural coatings still have many technical shortcomings in practical applications, especially under extreme environments (low temperature and high humidity, salt spray corrosion), which limit their applicability and effectiveness.

[0003] First, the film-forming properties of existing water-based coatings are highly dependent on ambient temperature and humidity. In low-temperature and high-humidity environments (such as winter construction or the rainy season in southern China), the film-forming speed of the coating slows down significantly, and in some cases, complete film formation may not occur. Simultaneously, the adhesion between the coating and the substrate decreases considerably after film formation, leading to peeling and cracking, which severely impacts construction efficiency and coating lifespan. While some existing low-temperature curing water-based coatings attempt to lower the curing temperature, problems such as incomplete curing and unstable coating performance still exist, making it difficult to meet actual construction needs.

[0004] Secondly, in environments with high salt spray concentrations, such as coastal areas and around chemical plants, building substrates (especially metal and concrete substrates) are prone to corrosion. Existing water-based coatings lack sufficient rust and corrosion protection, easily leading to problems such as flash rust, coating blistering, and peeling. They cannot effectively isolate the substrate from the erosion of salt spray and moisture, resulting in decreased building structure durability and increased maintenance costs. Currently used corrosion inhibitors are mostly added directly, which are prone to hydrolysis and failure, failing to achieve long-term corrosion inhibition and potentially affecting the stability and environmental friendliness of the coatings.

[0005] In addition, to adapt to the deformation requirements of building substrates (such as wall cracking and thermal expansion and contraction of substrates), some architectural coatings add elastic emulsions to improve the elasticity of the coating. However, the introduction of elastic emulsions often leads to increased hydrophilicity of the coating surface, decreased stain resistance, easy adsorption of dust and stains, and difficulty in cleaning. This creates a contradiction that the better the elasticity, the worse the stain resistance, and it is impossible to meet the requirements of both elastic protection and clean appearance of the coating. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects of the existing technology. The present invention proposes an environmentally friendly water-based coating for building and its processing method.

[0007] To address the aforementioned issues, existing waterborne coatings suffer from significant dependence on ambient temperature and humidity for film-forming performance. In low-temperature, high-humidity environments, film formation slows considerably, sometimes even failing to form a complete film. Furthermore, the adhesion between the coating and substrate decreases drastically after film formation, leading to peeling and cracking, severely impacting construction efficiency and coating lifespan. While some low-temperature curing waterborne coatings attempt to lower curing temperatures, incomplete curing and unstable coating performance remain, failing to meet practical construction needs. Secondly, in coastal areas and around chemical plants with high salt spray concentrations, building substrates are prone to corrosion. Existing waterborne coatings lack sufficient rust and corrosion protection, exhibiting issues like flash rust, blistering, and peeling. They cannot effectively isolate the substrate from salt spray and moisture erosion, reducing structural durability and increasing maintenance costs. Currently used corrosion inhibitors are often added directly, prone to hydrolysis and failure, failing to provide long-term corrosion inhibition and potentially affecting coating stability and environmental friendliness. Furthermore, to adapt to the deformation requirements of building substrates, some architectural coatings add elastic emulsions to enhance coating elasticity. However, the introduction of elastic emulsions often leads to increased hydrophilicity of the coating surface, decreased stain resistance, easy adsorption of dust and stains, and difficulty in cleaning. This creates a contradiction where better elasticity results in poorer stain resistance, failing to simultaneously address the technical problem of achieving both elastic protection and a clean appearance. The technical solution adopted in this invention is: An environmentally friendly water-based coating for construction, comprising the following components: 40-60 parts of elastic grafted hydrophobic emulsion, 5-10 parts of low-temperature activated crosslinking agent, 3-8 parts of corrosion inhibitor microcapsules, 15-25 parts of pigments and fillers, 1-3 parts of dispersant, 0.5-2 parts of wetting agent, 0.3-1 part of defoamer, 0.5-2 parts of thickener, 1-4 parts of film-forming aid, and 10-20 parts of deionized water; The elastic grafted hydrophobic emulsion is prepared by grafting hydrophobic side chains onto an acrylic elastic emulsion. The low-temperature activated crosslinking agent is a modified isocyanate crosslinking agent. The corrosion inhibitor microcapsules use zinc phosphate and sodium molybdate as the core material and polyurea-formaldehyde resin as the wall material.

[0008] Preferably, in the elastic grafted hydrophobic emulsion, the glass transition temperature of the acrylic elastic emulsion is -20℃ to -5℃, and the solid content is 45%-55%. The hydrophobic side chain is one or a combination of two of perfluorooctyl acrylate and methyltriethoxysilane, with a grafting rate of 8%-15%.

[0009] Preferably, the low-temperature activated crosslinking agent is prepared by reacting aliphatic isocyanate with polyethylene glycol monomethyl ether and diethanolamine, with an active group content of 12%-18% and an activation temperature of 3℃~8℃.

[0010] Preferably, in the corrosion inhibitor microcapsules, the weight ratio of zinc phosphate to sodium molybdate is 1:0.5-2, the wall material thickness is 1-5 μm, and the particle size is 5-20 μm.

[0011] Preferably, the pigments and fillers include one or more of titanium dioxide, talc, and barite powder, wherein the titanium dioxide is rutile and the particle size of the pigments and fillers is 2000-3000 mesh.

[0012] A processing method for an environmentally friendly water-based coating for construction includes the following steps: Step 1: Prepare an elastic grafted hydrophobic emulsion; Step 2: Preparation of corrosion inhibitor microcapsules; Step 3: Prepare a low-temperature activated crosslinking agent; Step 4: Sequentially mix deionized water, dispersant, wetting agent, pigments and fillers, elastic grafted hydrophobic emulsion, corrosion inhibitor microcapsules, low-temperature activated crosslinking agent, film-forming aid, defoamer, and thickener, adjust the viscosity, and filter to obtain the finished product. Preferably, in step 1, the preparation method of the elastic grafted hydrophobic emulsion is as follows: The acrylic elastic emulsion is heated to 60-70℃, and a hydrophobic monomer and initiator are added. The reaction is maintained at this temperature for 2-3 hours, and then cooled and filtered to obtain the final product. The initiator is ammonium persulfate, and the amount used is 0.5%-1.5% of the weight of the hydrophobic monomer.

[0013] Preferably, in step 2, the method for preparing the corrosion inhibitor microcapsules is as follows: Zinc phosphate and sodium molybdate are mixed as core material and added to an aqueous solution of polyurea-formaldehyde resin prepolymer. The pH is adjusted to 3.5-4.5, the temperature is raised to 50-60℃, and the reaction is carried out for 1.5-2.5 hours. The mixture is then centrifuged, washed, dried, pulverized, and sieved to obtain the final product.

[0014] Preferably, in step 3, the preparation method of the low-temperature activated crosslinking agent is as follows: Aliphatic isocyanate was added to a reaction vessel and heated to 40-50℃. The stirring speed was 100-200 r / min. A mixture of polyethylene glycol monomethyl ether and diethanolamine was slowly added dropwise. The weight ratio of polyethylene glycol monomethyl ether to diethanolamine was 2:1-3. After the addition was complete, the temperature was raised to 65-75℃ and the reaction was maintained for 1-2 hours. After the reaction was completed, the temperature was lowered to room temperature to obtain a low-temperature activated crosslinking agent.

[0015] Compared with the prior art, the present invention has the following significant advantages: This invention uses a low-temperature activated modified isocyanate crosslinking agent with a low activation temperature (3℃~8℃), which can achieve rapid crosslinking and curing at around 5℃, significantly shortening the film-forming time (film-forming time ≤4h, while the film-forming time of existing technologies is ≥8h). At the same time, the modified crosslinking agent has good compatibility with the elastic grafted hydrophobic emulsion, improving the crosslinking density of the coating and enabling the adhesion between the coating and the substrate to reach level 1 (GB / T9286-1998), thus avoiding coating peeling and cracking under low temperature and high humidity conditions.

[0016] This invention uses corrosion inhibitor microcapsules with polyurea-formaldehyde resin as the wall material, which can control the release rate of the corrosion inhibitor and avoid rapid hydrolysis failure of the corrosion inhibitor, thus achieving long-term corrosion inhibition. According to the test, the coating has a salt spray resistance time of ≥1000h in the neutral salt spray test (GB / T1771-2007), with no flash rust, no blistering, and no peeling. The corrosion inhibition period is ≥5 years, which can effectively adapt to salt spray corrosion environments such as coastal areas and chemical plants.

[0017] This invention prepares an elastic grafted hydrophobic emulsion by grafting hydrophobic side chains onto an acrylic elastic emulsion, giving the coating both good elasticity (elongation ≥300%, GB / T16777-2008), adaptability to substrate deformation, and excellent stain resistance (contact angle ≥105°, stain adhesion ≤5g / m², easy to clean), achieving a perfect balance between elasticity and stain resistance, and overcoming the shortcomings of poor stain resistance in existing elastic coatings. Attached Figure Description

[0018] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts. Wherein: Figure 1 This is a schematic diagram illustrating the component relationships and functions of the environmentally friendly water-based coating for building applications of the present invention. Figure 2 This is a simplified structural diagram of the elastic grafted hydrophobic emulsion of the present invention; Figure 3 This is a flowchart of the processing method for the environmentally friendly water-based coating for building applications according to the present invention. Detailed Implementation

[0019] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0020] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0021] Please see Figures 1-3 An environmentally friendly water-based coating for construction, comprising the following components by weight: 40-60 parts of elastic grafted hydrophobic emulsion, 5-10 parts of low-temperature activated crosslinking agent, 3-8 parts of corrosion inhibitor microcapsules, 15-25 parts of pigments and fillers, 1-3 parts of dispersant, 0.5-2 parts of wetting agent, 0.3-1 part of defoamer, 0.5-2 parts of thickener, 1-4 parts of film-forming aid, and 10-20 parts of deionized water.

[0022] Detailed description of each component Elastic grafted hydrophobic emulsion: As a film-forming base material for coatings, it provides elasticity and basic adhesion to the coating. Simultaneously, through the grafting of hydrophobic side chains, it enhances the coating's anti-fouling properties, resolving the contradiction between elasticity and anti-fouling performance. The elastic grafted hydrophobic emulsion uses acrylic elastic emulsion as a base material, prepared by grafting hydrophobic side chains via emulsion polymerization. The acrylic elastic emulsion has a glass transition temperature of -20℃ to -5℃ and a solid content of 45%-55%, ensuring good elasticity and a good low-temperature film-forming foundation for the coating. The hydrophobic side chains are composed of one or two of perfluorooctyl acrylate and methyltriethoxysilane, with a grafting rate of 8%-15%. Through the directional arrangement of the hydrophobic side chains on the coating surface, a hydrophobic protective layer is formed, effectively improving the coating's anti-fouling and waterproof properties without affecting the emulsion's elasticity and compatibility.

[0023] Low-temperature activated crosslinking agent: Used to lower the curing temperature of coatings, enabling rapid film formation in low-temperature environments, while simultaneously increasing the crosslinking density of the coating and enhancing the adhesion between the coating and the substrate. This low-temperature activated crosslinking agent is a modified isocyanate crosslinking agent, specifically prepared by modifying aliphatic isocyanates with polyethylene glycol monomethyl ether and diethanolamine. Its active group content is 12%-18%, and the activation temperature is 3℃~8℃. It can achieve rapid crosslinking and curing at around 5℃, solving the problems of slow film formation and decreased adhesion under low temperature and high humidity conditions. Compared with existing ordinary isocyanate crosslinking agents, the modified crosslinking agent has better compatibility with elastic grafted hydrophobic emulsions, avoiding defects such as pinholes and cracking during the crosslinking process, while also improving the coating's water resistance and mechanical strength.

[0024] Corrosion inhibitor microcapsules: These are used to achieve long-term corrosion inhibition, prevent substrate corrosion in salt spray environments, and avoid coating flash rust and blistering. The microcapsules are prepared via in-situ polymerization using an inorganic corrosion inhibitor as the core material and polyurea-formaldehyde resin as the wall material. The core material is a compound corrosion inhibitor of zinc phosphate and sodium molybdate in a weight ratio of 1:0.5–2, which synergistically enhances the corrosion inhibition effect and is suitable for various substrates such as metals and concrete. The wall material thickness is 1–5 μm, and the particle size is 5–20 μm, which controls the release rate of the corrosion inhibitor, preventing rapid hydrolysis and failure, and achieving long-term corrosion inhibition (inhibition period ≥ 5 years). Simultaneously, the microcapsule structure prevents the corrosion inhibitor from reacting with other components of the coating, ensuring the stability of the coating system. Furthermore, it is environmentally friendly, free of heavy metal pollution, and meets environmental protection requirements.

[0025] Pigments and fillers: Used to adjust the color, hiding power, and mechanical strength of coatings. Environmentally friendly pigments and fillers are selected, free of harmful substances. Pigments and fillers include one or more of titanium dioxide, talc, and barite powder in combination; among them, rutile titanium dioxide is selected, with a hiding power ≥12g / m², used to improve the hiding power and weather resistance of the coating; talc and barite powder have a particle size of 2000-3000 mesh, used to improve the hardness and abrasion resistance of the coating, and improve the leveling properties of the coating during application.

[0026] Dispersant: Used to disperse pigments and fillers, prevent pigments and fillers from agglomerating, and improve the stability and leveling properties of coatings. Water-based sodium polyacrylate dispersants with a molecular weight of 5000-10000 are selected. They can effectively reduce the surface tension of pigments and fillers, achieve uniform dispersion, and avoid phenomena such as blooming and sedimentation in the coating.

[0027] Wetting agents: used to improve the wettability of coatings on substrates and enhance the adhesion between coatings and substrates. Non-ionic wetting agents (such as polyoxyethylene alkyl ethers) are selected, which are free of APEO, environmentally friendly and pollution-free. They can reduce the surface tension of coatings and ensure that coatings are evenly spread on the substrate surface, especially suitable for low surface energy substrates.

[0028] Defoamer: Used to eliminate bubbles generated during the production and application of coatings, and to prevent defects such as pinholes and bubbles in the coating. Organosilicon defoamers are selected because they have a fast defoaming speed, a long foam suppression time, and good compatibility with the coating system, without affecting the appearance and performance of the coating.

[0029] Thickener: Used to adjust the viscosity of the coating and improve its leveling properties during application. Associative polyurethane thickeners are selected because they have good thickening effects and excellent anti-splatter properties. The viscosity of the coating can be adjusted to 1000-5000 mPa·s (25℃) according to the application requirements, ensuring that the coating maintains good leveling properties and does not cause problems such as sagging or accumulation when applied by brushing, rolling, or spraying.

[0030] Film-forming aids: Used to assist in the film formation of coatings and reduce the minimum film-forming temperature of coatings. Environmentally friendly film-forming aids (such as propylene glycol methyl ether acetate and dodecyl alcohol ester) with VOC content ≤5g / L are selected. They can assist in the film formation of coatings under low temperature conditions, while improving the continuity and density of the coating and avoiding phenomena such as powdering and cracking of the coating.

[0031] Deionized water: As a dispersion medium for coatings, it is free of impurities, thus avoiding affecting the stability and performance of the coating and ensuring the uniformity of the coating system.

[0032] A processing method for environmentally friendly water-based coatings for construction. This processing method is applied to the production and processing of the aforementioned environmentally friendly water-based coatings, and specifically includes the following steps: Step 1: Preparation of elastic grafted hydrophobic emulsion Add the acrylic elastic emulsion to a reaction vessel, heat to 60-70℃, adjust the stirring speed to 200-300 r / min, add the hydrophobic monomer (one or a combination of perfluorooctyl acrylate and methyltriethoxysilane) and the initiator (ammonium persulfate). The amount of initiator is 0.5%-1.5% of the weight of the hydrophobic monomer. Keep the reaction at this temperature for 2-3 hours. After the reaction is complete, cool to room temperature, filter to remove impurities, and obtain the elastic grafted hydrophobic emulsion. The amount of hydrophobic monomer added is 8%-15% of the weight of the acrylic elastic emulsion to ensure that the grafting rate reaches 8%-15%.

[0033] Step 2: Preparation of corrosion inhibitor microcapsules Zinc phosphate and sodium molybdate are mixed evenly at a weight ratio of 1:0.5-2 to form the core material. Polyurea-formaldehyde resin prepolymer is added to deionized water and stirred to dissolve. The core material is then added, and the pH of the system is adjusted to 3.5-4.5. The temperature is raised to 50-60℃, and the stirring speed is 150-250 r / min. The reaction is maintained at this temperature for 1.5-2.5 h to form a microcapsule suspension. The suspension is centrifuged, washed 3-4 times, dried until the moisture content is ≤1%, pulverized, and sieved (sieve mesh size is 20 μm) to obtain corrosion inhibitor microcapsules.

[0034] Step 3: Preparation of low-temperature activated crosslinking agent Aliphatic isocyanate was added to a reaction vessel and heated to 40-50℃. The stirring speed was 100-200 r / min. A mixture of polyethylene glycol monomethyl ether and diethanolamine was slowly added dropwise. The weight ratio of polyethylene glycol monomethyl ether to diethanolamine was 2:1-3. After the addition was complete, the temperature was raised to 65-75℃ and the reaction was maintained for 1-2 hours. After the reaction was completed, the temperature was lowered to room temperature to obtain a low-temperature activated crosslinking agent.

[0035] Step 4: Preparation of environmentally friendly water-based coatings 1. Add deionized water to the dispersion vessel, turn on the stirrer, adjust the speed to 300-400 r / min, add the dispersant and wetting agent in sequence, and stir for 5-10 min to make them completely dissolved; 2. Keep the stirring speed constant, slowly add the pigments and fillers, and continue stirring for 20-30 minutes until the pigments and fillers are evenly dispersed and the system is free of obvious particles; 3. Reduce the stirring speed to 200-300 r / min, add the elastic grafted hydrophobic emulsion and corrosion inhibitor microcapsules, and stir for 15-20 min to ensure that all components are evenly mixed. 4. Add the low-temperature activated crosslinking agent, film-forming aid, and defoamer in sequence, and stir for 10-15 minutes; 5. Finally, add thickener to adjust the viscosity of the coating to 1000-5000 mPa·s (25℃), stir for 5-10 minutes, filter to remove impurities, and obtain environmentally friendly water-based coating for construction.

[0036] Step 5: Finished Product Inspection and Packaging The prepared environmentally friendly water-based coatings are subjected to performance testing. The test indicators include film-forming temperature, adhesion, salt spray resistance, elasticity, stain resistance, and VOC content. After meeting the relevant standards, the coatings are filled and packaged and stored in a cool, dry place, avoiding direct sunlight and high-temperature environments.

[0037] Example 1 An environmentally friendly water-based coating for construction, by weight, comprises the following components: 40 parts of elastic grafted hydrophobic emulsion, 5 parts of low-temperature activated crosslinking agent, 3 parts of corrosion inhibitor microcapsules, 15 parts of pigments and fillers (8 parts of titanium dioxide + 7 parts of talc), 1 part of dispersant, 0.5 parts of wetting agent, 0.3 parts of defoamer, 0.5 parts of thickener, 1 part of film-forming aid, and 10 parts of deionized water.

[0038] The processing method is as follows: Step 1: Preparation of elastic grafted hydrophobic emulsion: Add 40 parts of acrylic elastic emulsion (glass transition temperature -20℃, solid content 45%) to the reactor, heat to 60℃, stir at 200 r / min, add 3.2 parts of perfluorooctyl acrylate (hydrophobic monomer) and 0.032 parts of ammonium persulfate (initiator), keep the reaction at this temperature for 2 hours, cool to room temperature, and filter to obtain elastic grafted hydrophobic emulsion (grafting rate 8%).

[0039] Step 2: Preparation of corrosion inhibitor microcapsules: Mix 2 parts zinc phosphate and 1 part sodium molybdate as core material; dissolve polyurea-formaldehyde resin prepolymer in deionized water, add core material, adjust pH to 3.5, heat to 50℃, stir at 150 r / min, keep warm for 1.5 h, centrifuge, wash, dry, pulverize and sieve to obtain corrosion inhibitor microcapsules.

[0040] Step 3: Preparation of low-temperature activated crosslinking agent: Add 5 parts of aliphatic isocyanate to the reaction vessel, heat to 40℃, stir at 100r / min, add dropwise a mixture of 3.3 parts of polyethylene glycol monomethyl ether and 1.7 parts of diethanolamine, heat to 65℃ after the addition is complete, keep the reaction at this temperature for 1h, and cool down to obtain the low-temperature activated crosslinking agent (active group content 12%).

[0041] Step 4: Preparation of environmentally friendly water-based coating: Add 10 parts of deionized water to a dispersion vessel, stir at 300 r / min, add 1 part of dispersant and 0.5 parts of wetting agent, stir for 5 min; add 15 parts of pigments and fillers, stir for 20 min; reduce the stirring speed to 200 r / min, add 40 parts of elastic grafted hydrophobic emulsion and 3 parts of corrosion inhibitor microcapsules, stir for 15 min; add 5 parts of low-temperature activated crosslinking agent, 1 part of film-forming aid and 0.3 parts of defoamer, stir for 10 min; add 0.5 parts of thickener, adjust the viscosity to 1000 mPa·s, stir for 5 min, and filter to obtain the finished product.

[0042] Performance testing: Film-forming temperature 3℃, film-forming time at 5℃ 4h, adhesion grade 1, salt spray resistance time 1000h, elongation 300%, contact angle 105°, VOC content 8g / L, all of which meet relevant standards.

[0043] Example 2 An environmentally friendly water-based coating for construction, by weight, comprises the following components: 50 parts of elastic grafted hydrophobic emulsion, 7 parts of low-temperature activated crosslinking agent, 5 parts of corrosion inhibitor microcapsules, 20 parts of pigments and fillers (10 parts of titanium dioxide + 10 parts of barite powder), 2 parts of dispersant, 1.2 parts of wetting agent, 0.6 parts of defoamer, 1.2 parts of thickener, 2.5 parts of film-forming aid, and 15 parts of deionized water.

[0044] The processing method is as follows: Step 1: Preparation of elastic grafted hydrophobic emulsion: Add 50 parts of acrylic elastic emulsion (glass transition temperature -12℃, solid content 50%) to the reactor, heat to 65℃, stir at 250 r / min, add 5 parts of methyltriethoxysilane (hydrophobic monomer) and 0.05 parts of ammonium persulfate (initiator), keep the reaction at this temperature for 2.5 h, cool to room temperature, and filter to obtain elastic grafted hydrophobic emulsion (grafting rate 10%).

[0045] Step 2: Preparation of corrosion inhibitor microcapsules: Mix 3 parts zinc phosphate and 2 parts sodium molybdate as core material; dissolve polyurea-formaldehyde resin prepolymer in deionized water, add core material, adjust pH to 4.0, heat to 55℃, stir at 200 r / min, keep warm for 2 h, centrifuge, wash, dry, pulverize and sieve to obtain corrosion inhibitor microcapsules.

[0046] Step 3: Preparation of low-temperature activated crosslinking agent: Add 7 parts of aliphatic isocyanate to the reactor, heat to 45°C, stir at 150 r / min, add dropwise a mixture of 4.7 parts of polyethylene glycol monomethyl ether and 2.3 parts of diethanolamine, heat to 70°C after the addition is complete, keep the reaction at this temperature for 1.5 h, and then cool to obtain the low-temperature activated crosslinking agent (active group content 15%).

[0047] Step 4: Preparation of environmentally friendly water-based coating: Add 15 parts of deionized water to the dispersion vessel, stir at 350 r / min, add 2 parts of dispersant and 1.2 parts of wetting agent, stir for 8 min; add 20 parts of pigments and fillers, stir for 25 min; reduce the stirring speed to 250 r / min, add 50 parts of elastic grafted hydrophobic emulsion and 5 parts of corrosion inhibitor microcapsules, stir for 18 min; add 7 parts of low-temperature activated crosslinking agent, 2.5 parts of film-forming aid and 0.6 parts of defoamer, stir for 12 min; add 1.2 parts of thickener, adjust the viscosity to 3000 mPa·s, stir for 8 min, and filter to obtain the finished product.

[0048] Performance testing: Film-forming temperature 5℃, film-forming time at 5℃ 3h, adhesion grade 1, salt spray resistance time 1200h, elongation 350%, contact angle 110°, VOC content 7g / L, all of which meet relevant standards.

[0049] Example 3 An environmentally friendly water-based coating for construction, by weight, comprises the following components: 60 parts of elastic grafted hydrophobic emulsion, 10 parts of low-temperature activated crosslinking agent, 8 parts of corrosion inhibitor microcapsules, 25 parts of pigments and fillers (12 parts of titanium dioxide + 8 parts of talc + 5 parts of barite powder), 3 parts of dispersant, 2 parts of wetting agent, 1 part of defoamer, 2 parts of thickener, 4 parts of film-forming aid, and 20 parts of deionized water.

[0050] The processing method is as follows: Step 1: Preparation of elastic grafted hydrophobic emulsion: Add 60 parts of acrylic elastic emulsion (glass transition temperature -5℃, solid content 55%) to the reactor, heat to 70℃, stir at 300 r / min, add 9 parts of a complex hydrophobic monomer of perfluorooctyl acrylate and methyltriethoxysilane (weight ratio 1:1) and 0.135 parts of ammonium persulfate (initiator), keep the reaction at this temperature for 3 h, cool to room temperature, and filter to obtain elastic grafted hydrophobic emulsion (grafting rate 15%).

[0051] Step 2: Preparation of corrosion inhibitor microcapsules: Mix 4 parts zinc phosphate and 4 parts sodium molybdate as core material; dissolve polyurea-formaldehyde resin prepolymer in deionized water, add core material, adjust pH to 4.5, heat to 60℃, stir at 250 r / min, keep warm for 2.5 h, centrifuge, wash, dry, pulverize and sieve to obtain corrosion inhibitor microcapsules.

[0052] Step 3: Preparation of low-temperature activated crosslinking agent: Add 10 parts of aliphatic isocyanate to the reactor, heat to 50°C, stir at 200 r / min, add dropwise a mixture of 6.7 parts of polyethylene glycol monomethyl ether and 3.3 parts of diethanolamine, heat to 75°C after the addition is complete, keep the reaction at this temperature for 2 hours, and then cool to obtain the low-temperature activated crosslinking agent (active group content 18%).

[0053] Step 4: Preparation of environmentally friendly water-based coating: Add 20 parts of deionized water to the dispersion vessel, stir at 400 r / min, add 3 parts of dispersant and 2 parts of wetting agent, stir for 10 min; add 25 parts of pigments and fillers, stir for 30 min; reduce the stirring speed to 300 r / min, add 60 parts of elastic grafted hydrophobic emulsion and 8 parts of corrosion inhibitor microcapsules, stir for 20 min; add 10 parts of low-temperature activated crosslinking agent, 4 parts of film-forming aid and 1 part of defoamer, stir for 15 min; add 2 parts of thickener, adjust the viscosity to 5000 mPa·s, stir for 10 min, and filter to obtain the finished product.

[0054] Performance testing: Film forming temperature 8℃, film forming time at 5℃ 2.5h, adhesion grade 1, salt spray resistance time 1500h, elongation 400%, contact angle 115°, VOC content 6g / L, all of which meet relevant standards.

[0055] Comparative test The coating prepared in Example 2 of this invention was compared with conventional environmentally friendly water-based coatings (control group) in the prior art in terms of performance. The comparison results are shown in the table below: Comparative tests show that the environmentally friendly water-based coating for building prepared by this invention is significantly superior to existing technologies in terms of film-forming temperature, film-forming time, adhesion, salt spray resistance, elasticity, stain resistance (contact angle), and environmental performance (VOC content).

[0056] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. An environmentally friendly water-based coating for construction, characterized in that, By weight, it includes the following components: 40-60 parts of elastic grafted hydrophobic emulsion, 5-10 parts of low-temperature activated crosslinking agent, 3-8 parts of corrosion inhibitor microcapsules, 15-25 parts of pigments and fillers, 1-3 parts of dispersant, 0.5-2 parts of wetting agent, 0.3-1 part of defoamer, 0.5-2 parts of thickener, 1-4 parts of film-forming aid, and 10-20 parts of deionized water; The elastic grafted hydrophobic emulsion is prepared by grafting hydrophobic side chains onto an acrylic elastic emulsion. The low-temperature activated crosslinking agent is a modified isocyanate crosslinking agent. The corrosion inhibitor microcapsules use zinc phosphate and sodium molybdate as the core material and polyurea-formaldehyde resin as the wall material.

2. The environmentally friendly water-based coating for building applications according to claim 1, characterized in that, In the aforementioned elastic grafted hydrophobic emulsion, the glass transition temperature of the acrylic elastic emulsion is -20℃ to -5℃, and the solid content is 45%-55%. The hydrophobic side chain is one or a combination of two of perfluorooctyl acrylate and methyltriethoxysilane, with a grafting rate of 8%-15%.

3. The environmentally friendly water-based coating for building applications according to claim 1, characterized in that, The low-temperature activated crosslinking agent is prepared by reacting aliphatic isocyanate with polyethylene glycol monomethyl ether and diethanolamine, with an active group content of 12%-18% and an activation temperature of 3℃~8℃.

4. The environmentally friendly water-based coating for building applications according to claim 1, characterized in that, In the corrosion inhibitor microcapsules, the weight ratio of zinc phosphate to sodium molybdate is 1:0.5-2, the wall material thickness is 1-5 μm, and the particle size is 5-20 μm.

5. The environmentally friendly water-based coating for building applications according to claim 1, characterized in that, The pigments and fillers include one or more of titanium dioxide, talc, and barite powder, with the titanium dioxide being rutile and the pigments and fillers having a particle size of 2000-3000 mesh.

6. The processing method of the environmentally friendly water-based coating for building according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Prepare an elastic grafted hydrophobic emulsion; Step 2: Preparation of corrosion inhibitor microcapsules; Step 3: Prepare a low-temperature activated crosslinking agent; Step 4: Mix deionized water, dispersant, wetting agent, pigments and fillers, elastic grafted hydrophobic emulsion, corrosion inhibitor microcapsules, low-temperature activated crosslinking agent, film-forming aid, defoamer, and thickener in sequence, adjust the viscosity, and filter to obtain the finished product.

7. The environmentally friendly water-based coating for building applications according to claim 6, characterized in that, In step 1, the preparation method of the elastic grafted hydrophobic emulsion is as follows: The acrylic elastic emulsion is heated to 60-70℃, and a hydrophobic monomer and initiator are added. The reaction is maintained at this temperature for 2-3 hours, and then cooled and filtered to obtain the final product. The initiator is ammonium persulfate, and the amount used is 0.5%-1.5% of the weight of the hydrophobic monomer.

8. The environmentally friendly water-based coating for building applications according to claim 6, characterized in that, In step 2, the method for preparing the corrosion inhibitor microcapsules is as follows: Zinc phosphate and sodium molybdate are mixed as core material and added to an aqueous solution of polyurea-formaldehyde resin prepolymer. The pH is adjusted to 3.5-4.5, the temperature is raised to 50-60℃, and the reaction is carried out for 1.5-2.5 hours. The mixture is then centrifuged, washed, dried, pulverized, and sieved to obtain the final product.

9. The environmentally friendly water-based coating for building applications according to claim 6, characterized in that, In step 3, the preparation method of the low-temperature activated crosslinking agent is as follows: Aliphatic isocyanate was added to a reaction vessel and heated to 40-50℃. The stirring speed was 100-200 r / min. A mixture of polyethylene glycol monomethyl ether and diethanolamine was slowly added dropwise. The weight ratio of polyethylene glycol monomethyl ether to diethanolamine was 2:1-3. After the addition was complete, the temperature was raised to 65-75℃ and the reaction was maintained for 1-2 hours. After the reaction was completed, the temperature was lowered to room temperature to obtain a low-temperature activated crosslinking agent.

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