A water-based composite coating and a method for preparing the same

Abstract

The application discloses a kind of water-based composite coating and preparation method thereof, the water-based composite coating includes A component and B component;The A component includes the following raw materials: 30~40 parts composite monomer, 10~25 parts water-based epoxy resin, 1~3 parts crosslinking agent, 2~3 parts coupling agent, and 20~40 parts water;Wherein, the composite monomer includes soft monomer and hard monomer, the soft monomer and hard monomer are copolymerized in situ to form acrylic resin segment, the B component includes the following raw materials: 10~20 parts curing agent, 20~35 parts filler, 0.5~2 parts defoaming agent, 0.5~2 parts leveling agent and 10~30 parts water, using water-based epoxy resin as matrix, by soft monomer and hard monomer in A component after mixing copolymerization in situ, construct the acrylic resin segment with specific glass transition temperature, so that the coating has the "shielding" of epoxy resin and the "flexible weather resistance" of acrylic resin, cooperate other reagents to solve the technical problems of poor water resistance, weak adhesion and brittle fracture at low temperature in extreme environment.

Description

Technical Field

[0001] This invention relates to the field of waterborne coatings technology, specifically to a waterborne composite coating and its preparation method. Background Technology

[0002] With the development of society and economy, water-based coatings have replaced some solvent-based coatings and become the focus of attention in various fields. Among them, the development of acrylic coatings has been particularly rapid.

[0003] However, there are also some problems in practical applications. Acrylic polymers are easy to water-based, have high surface energy, and have strong adhesion to most coatings and inks. However, they have poor adhesion in environments such as marine environments, are prone to low-temperature embrittlement, and have poor high and low temperature resistance. Therefore, they limit the application fields of acrylic resins. Summary of the Invention

[0004] The main objective of this invention is to propose a water-based composite coating that addresses the problems of existing acrylic coatings becoming brittle at low temperatures and exhibiting poor high and low temperature resistance when applied to extreme environments.

[0005] To achieve the above objectives, the present invention provides a water-based composite coating comprising component A and component B; Component A comprises the following raw materials in parts by weight: 30-40 parts of composite monomer, 10-25 parts of waterborne epoxy resin, 0.2-1.5 parts of initiator, 1-3 parts of crosslinking agent, 2-3 parts of coupling agent, and 20-40 parts of water; wherein the composite monomer comprises soft monomer and hard monomer, and the soft monomer and hard monomer are copolymerized in situ to form acrylic resin segments; Component B comprises the following raw materials in parts by weight: 10-20 parts curing agent, 20-35 parts filler, 0.5-2 parts defoamer, 0.5-2 parts leveling agent, and 10-30 parts water.

[0006] Optionally, the mass ratio of the soft monomer to the hard monomer is 1:(0.5~1); and / or, The soft monomer includes at least one of butyl acrylate, isooctyl acrylate, and ethyl acrylate; and / or, The hard monomers include methyl methacrylate or styrene.

[0007] Optionally, the filler comprises at least one of nano-silica, nano-calcium carbonate, and graphene; and / or, The coupling agent includes titanate coupling agents or silane coupling agents; and / or, The crosslinking agent includes hydroxyethyl methacrylate or hydroxyethyl acrylate; and / or, The initiator includes ammonium persulfate or potassium persulfate.

[0008] Optionally, the curing agent includes a water-based modified alicyclic amine or a polyether amine curing agent.

[0009] Optionally, the leveling agent comprises polyether siloxane.

[0010] Optionally, the defoamer includes polyether-modified siloxane.

[0011] Another aspect of the present invention provides a method for preparing a water-based composite coating, comprising: Preparation of S10 and Component A: Mix soft monomer, hard monomer, waterborne epoxy resin, crosslinking agent and coupling agent, filter, and seal package to obtain Component A; Preparation of S20 and Component B: The curing agent, water, defoamer, leveling agent and filler are mixed to obtain a mixture. The mixture is stirred, ground, filtered and sealed to obtain Component B. S30. Mix and stir the A component with the B component, and mature to obtain a water-based composite coating.

[0012] Optionally, step S10 includes: mixing and stirring the soft monomer, hard monomer and waterborne epoxy resin to obtain a pre-emulsion; The preemulsion was mixed with an initiator, a crosslinking agent, and a coupling agent, heated, cooled, filtered, and sealed in a package to obtain component A.

[0013] Optionally, in step S20, the stirring speed includes 1000~1500 r / min; and / or, The stirring time is 5 to 15 minutes.

[0014] Optionally, in step S20, the fineness of the grinding of the mixture is not greater than 45 micrometers.

[0015] The technical solution of this application utilizes the superior properties of waterborne epoxy resin as a matrix. The epoxy groups in its molecular structure can form a dense, highly cross-linked three-dimensional network structure after curing, endowing the coating with extremely high hardness, excellent adhesion, outstanding resistance to acid and alkali corrosion and solvent corrosion, as well as good electrical insulation properties. Simultaneously, through in-situ copolymerization of soft and hard monomers in component A, acrylic resin segments with specific glass transition temperatures are constructed, effectively compensating for the shortcomings of pure epoxy resin, such as high brittleness and poor weather resistance, and endowing the coating with excellent flexibility, impact resistance, and temperature change resistance. More importantly, by utilizing the unique amphiphilic molecular structure of the coupling agent, a strong "chemical bridge" is built between the organic coating and the inorganic substrate. This not only achieves high-strength chemical bonding between the coating and the substrate but also significantly reduces the water absorption rate of the coating through the dense inorganic network formed at the interface. This multi-dimensional deep cross-linking and synergistic modification enables the coating to combine the "shielding" properties of epoxy resin with the "flexibility and weather resistance" of acrylic resin, thereby solving the technical problems of poor water resistance, weak adhesion, and easy brittleness at low temperatures of traditional acrylic resin in harsh outdoor environments, and even extreme environments such as at sea. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, or solution B, or a solution where both A and B are satisfied simultaneously. In addition, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention. 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.

[0017] Water-based coatings have become a development trend in some industries. Acrylic resins, due to their good transparency, ability to improve the apparent hardness of materials, and excellent gloss and color retention, are widely used in home appliances, daily necessities and other fields. However, in practical applications, there are still some shortcomings that limit the use of acrylic resins, such as poor water resistance and low adhesion. Therefore, these limitations restrict the application areas of acrylic resins.

[0018] In view of this, the present invention provides a water-based composite coating comprising component A and component B; Component A comprises the following raw materials in parts by weight: 30-40 parts of composite monomer, 10-25 parts of waterborne epoxy resin, 0.2-1.5 parts of initiator, 1-3 parts of crosslinking agent, 2-3 parts of coupling agent, and 20-40 parts of water; wherein the composite monomer comprises soft monomer and hard monomer, and the soft monomer and hard monomer are copolymerized in situ to form acrylic resin segments; Component B comprises the following raw materials in parts by weight: 10-20 parts curing agent, 20-35 parts filler, 0.5-2 parts defoamer, 0.5-2 parts leveling agent, and 10-30 parts water.

[0019] The technical solution of this application utilizes the superior properties of waterborne epoxy resin as a matrix: the epoxy groups in its molecular structure can form a dense, highly cross-linked three-dimensional network structure after curing, endowing the coating with extremely high hardness, excellent adhesion, outstanding resistance to acid and alkali corrosion and solvent corrosion, as well as good electrical insulation properties. Simultaneously, by mixing soft and hard monomers in component A and then copolymerizing them in situ, acrylic resin segments with specific glass transition temperatures are constructed, effectively compensating for the shortcomings of pure epoxy resin, such as high brittleness and poor weather resistance, thus endowing the coating with excellent flexibility, impact resistance, and temperature change resistance. More importantly, by utilizing the unique amphiphilic molecular structure of the coupling agent, a strong "chemical bridge" is built between the organic coating and the inorganic substrate, not only achieving high-strength chemical bonding between the coating and the substrate, but also significantly reducing the water absorption rate of the coating through the dense inorganic network formed at the interface. This multi-dimensional deep cross-linking and synergistic modification enables the coating to combine the "shielding" properties of epoxy resin with the "flexibility and weather resistance" of acrylic resin, thereby solving the technical problems of poor water resistance, weak adhesion, and easy brittleness at low temperatures of traditional acrylic resin in harsh outdoor environments, and even extreme environments such as at sea.

[0020] Furthermore, in some embodiments, the mass ratio of the soft monomer to the hard monomer is 1:(0.5~1).

[0021] In this embodiment, the optimal balance of mechanical properties of the coating film was achieved by precisely controlling the rigid-flexible structure of the polymer molecular chains. Within this ratio range, the soft monomers endow the coating with excellent flexibility, impact resistance, and low-temperature film-forming ability, enabling it to adapt to the thermal expansion and contraction and deformation of the substrate; while an appropriate amount of hard monomers provides the necessary skeletal support, ensuring that the coating possesses excellent hardness, abrasion resistance, and chemical resistance. This synergistic effect of rigidity and flexibility effectively avoids the performance contradiction of "high hardness leads to brittleness, and good toughness leads to softness" in traditional coatings, resulting in a coating film that is both dense and tough yet elastic. This allows the coating to maintain structural integrity and long-term protective effectiveness in long-term, complex corrosive environments. Furthermore, this monomer ratio can produce acrylic resin segments with a glass transition temperature (Tg) suitable for use in harsh environments.

[0022] It should be noted that by precisely controlling the types and ratios of soft monomers (providing flexible segments) and hard monomers (providing a rigid framework), the acrylic resin segments formed by in-situ copolymerization have a preset glass transition temperature. This specific Tg value ensures that the coating maintains high hardness and excellent scratch resistance while also possessing outstanding low-temperature toughness and impact resistance, effectively avoiding the risk of brittle cracking of the coating under extreme temperature conditions.

[0023] Furthermore, the filler includes at least one of nano-silica, nano-calcium carbonate, and graphene.

[0024] This technical solution utilizes the aforementioned nanoparticles to densely fill the gaps between resin molecular chains, constructing a robust physical framework, thereby significantly improving the coating's hardness, wear resistance, and impact resistance. In particular, the introduction of sheet-like fillers such as graphene can form a "labyrinthine" barrier structure, greatly enhancing the coating's ability to shield against water vapor, oxygen, and corrosive media, providing long-lasting physical protection for the substrate.

[0025] In some embodiments, the coupling agent includes a titanate coupling agent or a silane coupling agent.

[0026] This technical solution constructs an "organic-inorganic" molecular bridge by introducing a modified coupling agent (chelated titanate or silane with double bonds) with a bifunctional structure. One end of this coupling agent chemically bonds to the hydroxyl groups on the surface of the nanofiller, while the other end participates in the polymerization or curing crosslinking of the acrylic resin, firmly "anchoring" the originally incompatible inorganic filler and organic resin network together through chemical bonds. This design not only achieves perfect compatibility between the filler and the matrix but also significantly improves the interfacial bonding force, enabling efficient stress transfer and endowing the coating with excellent adhesion and toughness. Simultaneously, this highly crosslinked, dense network structure significantly enhances the coating's water resistance, temperature resistance, and chemical corrosion resistance, solving the problems of easy hydrolysis and decreased adhesion of traditional water-based coatings in harsh environments.

[0027] In some embodiments, the crosslinking agent includes hydroxyethyl methacrylate or hydroxyethyl acrylate.

[0028] The key to using hydroxyethyl methacrylate or hydroxyethyl acrylate as crosslinking agents lies in utilizing the active hydroxyl groups inherent in their molecules as crucial chemical "anchors." These hydroxyl groups can undergo efficient and deep crosslinking reactions with the curing agent, weaving the originally linear acrylic resin molecular chains into an extremely dense and stable three-dimensional network. Once this highly crosslinked structure is formed, it not only significantly improves the surface hardness and scratch resistance of the coating but also constructs a strong physical barrier, effectively preventing the penetration of water molecules and corrosive media. This significantly enhances the water resistance and chemical resistance of the coating, providing solid molecular structural support for the long-term protection of the coating in harsh environments.

[0029] Furthermore, the initiator includes ammonium persulfate or potassium persulfate.

[0030] The above-mentioned water-soluble free radical initiator is perfectly suited to the aqueous in-situ emulsion polymerization system of this patent, ensuring that the soft and hard monomers undergo stable and efficient copolymerization reactions in the aqueous epoxy resin dispersion.

[0031] The curing agent includes water-based modified alicyclic amines or polyether amine curing agents.

[0032] It should be noted that these types of curing agents typically grant coatings a longer working time. For example, alicyclic amine curing agents have excellent hydrophobicity in their molecular structure. In water-based systems, they effectively reduce the affinity between the curing agent and water, significantly improving the paint film's resistance to water immersion, hot water, and salt spray corrosion after curing.

[0033] Furthermore, the leveling agent includes polyether siloxane. Using polyether siloxane as a leveling agent results in good wetting properties and low foaming, leading to a coating with excellent leveling effect.

[0034] Furthermore, the defoamer includes polyether-modified siloxane.

[0035] It should be noted that some defoamers have good defoaming ability but poor compatibility, which can easily lead to pinholes, while others have good compatibility but poor defoaming ability, which can easily lead to pinholes. Therefore, in order to achieve good defoaming effect without affecting the water resistance and adhesion of the coating, some embodiments use a polyether-modified structure to make it more compatible in the aqueous system. While achieving efficient defoaming, this greatly reduces the risk of secondary surface defects such as pinholes and oil spots caused by poor compatibility.

[0036] Another aspect of the present invention provides a method for preparing a water-based composite coating, comprising: Preparation of S10 and Component A: Mix soft monomer, hard monomer, waterborne epoxy resin, crosslinking agent and coupling agent, filter, and seal package to obtain Component A; Preparation of S20 and Component B: The curing agent, water, defoamer, leveling agent and filler are mixed to obtain a mixture. The mixture is stirred, ground, filtered and sealed to obtain Component B. S30. Mix and stir the A component with the B component, and mature to obtain a water-based composite coating.

[0037] The preparation method proposed in this invention achieves efficient utilization of raw materials and synergistic effects between components. The preparation process of component A ensures uniform dispersion and stable storage of functional resin, crosslinking agent, and coupling agent. Component B, through stirring and grinding processes, fully refines and homogenizes the filler in the curing agent system, improving the leveling and density of the coating. Finally, components A and B are mixed and cured in S30, which not only activates the crosslinking reaction and forms a dense and continuous coating network, but also significantly enhances the adhesion, water resistance, and mechanical properties of the coating. The entire process is simple to operate, highly adaptable, and easy to industrialize. Moreover, the resulting coating is environmentally friendly, non-toxic, and has excellent comprehensive performance.

[0038] Furthermore, the preparation method proposed in this invention produces a water-based composite coating that possesses all the beneficial effects of the aforementioned water-based composite coatings, which will not be elaborated upon here.

[0039] Further, step S10 includes: mixing and stirring the soft monomer, hard monomer and waterborne epoxy resin to obtain a pre-emulsion; The preemulsion was mixed with an initiator, a crosslinking agent, and a coupling agent, heated, cooled, filtered, and sealed in a package to obtain component A.

[0040] Using the above preparation method, acrylic resin segments are uniformly generated in the waterborne epoxy resin matrix through in-situ emulsion polymerization, constructing a stable hybrid network structure and achieving a synergistic improvement in material flexibility and anti-corrosion adhesion. The simultaneous addition of composite monomers and initiators, along with a high-temperature curing process in the later stage, effectively controls the polymerization reaction rate and avoids burst polymerization. This significantly improves monomer conversion rate and reduces free monomer residue while ensuring batch stability of the product. In addition, the process of adding aziridine crosslinking agent at low temperature successfully avoids premature crosslinking reaction at high temperature, ensuring the long-term storage stability of component A at room temperature and perfectly preserving the coating's efficient self-crosslinking curing performance during the film-forming stage.

[0041] Further, in step S20, the stirring speed includes 1000~1500 r / min, and the stirring time is 5~15 min.

[0042] Furthermore, the stirring time is 5 to 15 minutes, which can be 5 minutes, 10 minutes or 15 minutes. Within this range, the stirring is thorough, so that the components are mixed evenly and the reaction is complete.

[0043] Furthermore, in step S20, the mixture is stirred and ground, and the fineness of the grinding is no greater than 45 micrometers.

[0044] It should be noted that grinding and stirring are used here to ensure that the slurry is mixed evenly with the leveling agent, film-forming aid, monomer, and crosslinking agent, and that the reaction is complete.

[0045] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0046] Example 1 This embodiment provides a water-based composite coating, which includes the following components: Component A comprises the following raw materials in parts by weight: 35 parts composite monomer (a mixture of butyl acrylate and methyl methacrylate in a mass ratio of 1:1), 1 part initiator (ammonium persulfate), 15 parts waterborne epoxy resin (bisphenol A type waterborne epoxy resin dispersion, solid content 50%, epoxy equivalent 475 g / eq), 2 parts crosslinking agent (aziridine crosslinking agent XAMA-7), 2.5 parts coupling agent (silane coupling agent KH-560), and 30 parts water; Component B comprises the following raw materials in parts by weight: 15 parts curing agent (polyetheramine HD-3371), 25 parts filler (nano silica with an average particle size of 20-50nm), 1 part defoamer (polyether-modified siloxane defoamer NX-2005), 1 part leveling agent (polyether siloxane BYK-333), and 20 parts water, wherein each part is 1 kg.

[0047] The preparation method of the water-based composite coating includes the following steps: S10. Mix butyl acrylate and methyl methacrylate evenly as a composite monomer. Dissolve the initiator in deionized water to prepare an initiator aqueous solution, wherein each part of initiator corresponds to 5 parts of deionized water. In the reaction vessel, add the remaining deionized water, bisphenol A type aqueous epoxy resin dispersion, and coupling agent and mix. Start stirring and heat to 80°C. After the temperature stabilizes, add the above composite monomer and initiator aqueous solution dropwise simultaneously over 2.5 hours. After the dropwise addition is complete, heat to 88°C and maintain the temperature for 1.5 hours. Then cool to room temperature, add crosslinking agent, stir evenly, and filter through a 200-mesh filter to obtain component A. S20. Accurately weigh the reagents for component B. First, add the filler to a high-speed disperser according to the predetermined ratio and mix evenly at low speed (100~200 rpm). Then, gradually add deionized water and continue stirring for 10 minutes to initially wet the filler. Next, slowly add the curing agent to the disperser and increase the stirring speed to 900 rpm, dispersing for 25 minutes to ensure that the curing agent and filler are fully mixed. During this process, the temperature must be controlled not to exceed 40℃ to avoid premature reaction of the curing agent. Subsequently, add the defoamer and leveling agent to the disperser separately and continue dispersing for 15 minutes to further improve the stability and rheological properties of the system. Finally, transfer the mixed slurry to a sand mill for grinding, controlling the grinding time to 35 minutes, until the slurry fineness reaches below 40μm. During the grinding process, the slurry temperature needs to be monitored periodically. If it exceeds 50℃, cooling measures must be taken to prevent the system from overheating and causing performance degradation. The obtained component B needs to be filtered through a 200-mesh sieve to obtain component B. S30. Mix the prepared component A and component B at a mass ratio of 5:1. While stirring at a low speed of 300 rpm, slowly add component B to component A and continue stirring for 15 minutes to ensure that the two components are fully mixed. Then, transfer the mixture to a curing tank and cure it at room temperature (25±2℃) for 30 minutes to ensure that the chemical reaction between the two components is fully carried out. After curing, the water-based composite coating is obtained.

[0048] Examples 2-4 are similar to Example 1, except that the proportions of the components in the water-based composite coating are different. Please refer to Table 1 for details. The difference between Examples 5 and 6 and Example 1 is that the mass ratio of the soft monomer to the hard monomer is different. The mass ratio of the soft monomer to the hard monomer is R, and the specific parameters are detailed in Table 1. The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 did not add soft monomers, while the other components and proportions were the same as in Example 1. For specific parameters, please refer to Table 1. The difference between Comparative Example 2 and Example 2 is that Comparative Example 2 did not add epoxy resin, while the other components and proportions were the same as in Example 1. For specific parameters, please refer to Table 1.

[0049] Table 1

[0050] Performance testing The coatings prepared according to the embodiments and comparative examples of the present invention were subjected to performance tests. Table 2 shows the test results of the embodiments and comparative examples; wherein: Component A prepared in Example 1 was dried and film-formed, and then tested using a differential scanning calorimeter (DSC, TA Instruments Q2000). The test conditions were a nitrogen atmosphere, a heating rate of 10℃ / min, and the second heating curve was recorded. Data was read using the midpoint method. The test results showed that the glass transition temperature (Tg) of the acrylic resin segment formed by in-situ copolymerization was 3.5℃, confirming that this segment possesses excellent low-temperature toughness.

[0051] The water resistance test was conducted in accordance with GB / T 1733-1993 standard. The test panel coated with water-based composite coating was immersed in deionized water for 168 hours (7 days), and the surface changes were observed and the bubbling time was recorded.

[0052] Chemical resistance testing was conducted in accordance with GB / T 9274 "Determination of resistance to liquid media for paints and varnishes". The test method involved immersing the sample in a 10% NaOH solution for 48 hours by observing the changes in the appearance of the coating after immersion.

[0053] Salt spray resistance: Neutral salt spray test (NSS) 500 hours (refer to the standard requirements for industrial anti-corrosion coatings).

[0054] Hardness testing was conducted according to GB / T 6739-2006 standard, using a pencil hardness tester to test the coating, decreasing from 6H to B in increments until the maximum hardness level the coating could withstand was found.

[0055] Table 2 Test Results

[0056] As shown in Table 2, compared with the comparative examples, the test results of the examples are better in terms of overall performance. The lack of soft monomers in comparative example 1 caused the paint film to lose elasticity and crack. The lack of epoxy resin in comparative example 2 caused the chemical resistance to collapse. In addition, the performance of example 6 is worse than that of the other examples. This is because the excessive amount of hard monomers caused the paint film to be too brittle and crack. The appropriate amount of soft and hard monomers and epoxy resin in the other examples achieved a perfect balance between the hardness and flexibility of the paint film. They all showed excellent protective effects with dense, continuous and strong adhesion in long-term anti-corrosion tests such as water resistance, acid and alkali resistance and salt spray resistance.

[0057] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A water-based composite coating, characterized in that, Includes component A and component B; Component A comprises the following raw materials in parts by weight: 30-40 parts of composite monomer, 10-25 parts of waterborne epoxy resin, 0.2-1.5 parts of initiator, 1-3 parts of crosslinking agent, 2-3 parts of coupling agent, and 20-40 parts of water; wherein the composite monomer comprises soft monomer and hard monomer, and the soft monomer and hard monomer are copolymerized in situ to form acrylic resin segments; Component B comprises the following raw materials in parts by weight: 10-20 parts curing agent, 20-35 parts filler, 0.5-2 parts defoamer, 0.5-2 parts leveling agent, and 10-30 parts water.

2. The water-based composite coating as described in claim 1, characterized in that, The mass ratio of the soft monomer to the hard monomer is 1:(0.5~1); and / or, The soft monomer includes at least one of butyl acrylate, isooctyl acrylate, and ethyl acrylate; and / or, The hard monomers include methyl methacrylate or styrene.

3. The water-based composite coating as described in claim 1, characterized in that, The filler comprises at least one of nano-silica, nano-calcium carbonate, and graphene; and / or, The coupling agent includes titanate coupling agents or silane coupling agents; and / or, The crosslinking agent includes hydroxyethyl methacrylate or hydroxyethyl acrylate; and / or, The initiator includes ammonium persulfate or potassium persulfate.

4. The water-based composite coating as described in claim 1, characterized in that, The curing agent includes water-based modified alicyclic amines or polyether amine curing agents.

5. The water-based composite coating as described in claim 1, characterized in that, The leveling agent includes polyether siloxane.

6. The water-based composite coating as described in claim 1, characterized in that, The defoamer includes polyether-modified siloxane.

7. A method for preparing a water-based composite coating as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Preparation of S10 and Component A: Mix soft monomer, hard monomer, waterborne epoxy resin, crosslinking agent and coupling agent, filter, and seal package to obtain Component A; Preparation of S20 and Component B: The curing agent, water, defoamer, leveling agent and filler are mixed to obtain a mixture. The mixture is stirred, ground, filtered and sealed to obtain Component B. S30. Mix and stir the A component with the B component, and mature to obtain a water-based composite coating.

8. The method for preparing the water-based composite coating as described in claim 7, characterized in that, Step S10 includes: mixing and stirring the soft monomer, hard monomer and waterborne epoxy resin to obtain a pre-emulsion; The preemulsion was mixed with an initiator, a crosslinking agent, and a coupling agent, heated, cooled, filtered, and sealed in a package to obtain component A.

9. The method for preparing the water-based composite coating as described in claim 7, characterized in that, The stirring speed includes 1000~1500 r / min; and / or, The stirring time is 5 to 15 minutes.

10. The method for preparing the water-based composite coating as described in claim 7, characterized in that, In step S20, the mixture is stirred and ground, and the fineness of the grinding is no greater than 45 micrometers.

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