Primer and preparation method thereof

Abstract

The invention provides a primer and a preparation method thereof. The primer comprises the following components: water-borne epoxy resin, water-borne polyurea resin, modified wollastonite, a cross-linking agent, a curing agent and deionized water; the modified wollastonite comprises a wollastonite core and a polymer layer arranged on the surface of the wollastonite core, and the polymer layer comprises polydopamine. The modified wollastonite, the water-based polyurea resin, the cross-linking agent and other materials are introduced to synergistically solve the problem of cracks generated in the drying process of the epoxy resin primer, and the bonding durability and weather resistance of the primer under complex conditions are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of primer, and particularly relates to a primer and a preparation method thereof. BACKGROUND

[0002] Polyurethane sealant has become the first choice material in various sealing and bonding applications due to its excellent elasticity and durability. However, the isocyanate groups in its chemical properties tend to react with substances containing active hydrogen, which will lead to insufficient bonding performance in some application occasions. Especially in the bonding process with inert materials such as metal and glass, the bonding effect of polyurethane sealant is not ideal due to the lack of active hydrogen on the surface of these materials. The insufficient bonding performance is particularly prominent under harsh conditions such as high humidity, high temperature, mechanical load and natural environmental aging.

[0003] In order to solve this problem, it is urgent to develop a safe and environmentally friendly primer with good bonding effect to enhance the reliability and durability of polyurethane sealant in complex environments. SUMMARY

[0004] The application provides a primer, which has good durability, weather resistance and crack resistance, and has good bonding effect with metal substrates.

[0005] The application also provides a preparation method of the primer, which can prepare the primer and has simple preparation process and low cost.

[0006] In a first aspect, the application provides a primer, which comprises the following components:

[0007] water-based epoxy resin, water-based polyurea resin, modified wollastonite, crosslinking agent, curing agent, and deionized water;

[0008] The modified wollastonite comprises a wollastonite core and a polymer layer arranged on the surface of the wollastonite core, and the polymer layer comprises polydopamine.

[0009] In an optional embodiment, the components of the primer are as follows in terms of weight parts:

[0010] The water-based epoxy resin is 30-45 parts, the water-based polyurea resin is 15-30 parts, the modified wollastonite is 3-10 parts, the crosslinking agent is 0.5-2 parts, the curing agent is 10-20 parts, and the deionized water is 15-25 parts.

[0011] In an optional embodiment, the modified wollastonite is prepared by mixing wollastonite, a dopamine hydrochloride solution and a metal salt solution.

[0012] In an optional embodiment, the metal salt comprises copper sulfate.

[0013] In an optional embodiment, the mass ratio of the wollastonite, the dopamine hydrochloride solution and the metal salt solution is 2: (10-20): 1.

[0014] And / or, the concentration of the dopamine hydrochloride solution is 1-3 g / L.

[0015] And / or, the concentration of the metal salt solution is 1-2 g / L.

[0016] In an optional embodiment, the method for preparing the polymer-modified wollastonite comprises:

[0017] The wollastonite with a particle size of 2000-5000 is added into the dopamine hydrochloride solution to obtain a first intermediate;

[0018] The metal salt solution is added into the first intermediate, stirred at 25℃ for 1-3 h, and then filtered, washed, dried and crushed to obtain the polymer-modified wollastonite.

[0019] In an optional embodiment, the aqueous polyurea resin is an aqueous polyurethane urea dispersion and / or an aqueous aspartic polyurea resin emulsion.

[0020] In an optional embodiment, the crosslinking agent is at least one of polysiloxane powder, sodium methylsilicate, potassium methylsilicate and sodium methylsilanol.

[0021] In an optional embodiment, the curing agent is at least one of diethanolamine, triethanolamine, dimethylethanolamine and dimethylformamide.

[0022] In a second aspect, the present application provides a method for preparing the primer, comprising the following steps:

[0023] The aqueous epoxy resin, the aqueous polyurea resin and the modified wollastonite are mixed and stirred first, and then the crosslinking agent, the curing agent and deionized water are added and stirred to obtain the primer.

[0024] The primer of the present application significantly improves its bonding strength, durability, weather resistance and crack resistance by introducing the modified wollastonite, the aqueous polyurea resin and the crosslinking agent. Among them, the phenolic hydroxyl and amino groups on the surface of the modified wollastonite are enhanced by chemical bond or complexation reaction to improve the bonding strength, the high polarity of the aqueous polyurea resin improves the bonding force with the metal, and the silicon oxide or silicon alcohol structure in the crosslinking agent further strengthens the bonding effect through the secondary valence bond or chemical bond; in addition, the thermal stability of the modified wollastonite and the high crosslinking density of the polyurea resin also improve the heat resistance and weather resistance of the coating; at the same time, the hydrophobic layer formed by the crosslinking agent effectively prevents water vapor from attacking and avoids the cracking of the coating. The synergistic effect of these materials ensures the excellent performance of the primer in all aspects. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0026] Figure 1 The mechanism is that of dopamine hydrochloride modified wollastonite.

[0027] Figure 2 This shows the surface damage after the peel test under aging conditions in Example 1.

[0028] Figure 3 This is a comparison of the surface damage after the peel test under aging conditions in Example 1.

[0029] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0030] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0032] In this application, references to "an embodiment," "an example," or "an example" mean that a specific feature, structure, or characteristic described in connection with that embodiment, example, or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination.

[0033] Existing primers improve adhesive strength by modifying epoxy resin with silanes, but their performance remains insufficient under complex conditions such as high temperature and humidity, mechanical stress and vibration, and aging. In particular, epoxy resin is prone to cracking under high humidity or stress environments, weakening the effectiveness of the primer. Although modification with silane coupling agents improves adhesion and aging properties to some extent, the weather resistance of polyurethane primers remains poor, making it difficult to maintain stability over long-term use. Therefore, this invention provides the following solution:

[0034] In a first aspect, the present invention provides a primer comprising the following components:

[0035] Waterborne epoxy resin, waterborne polyurea resin, modified wollastonite, crosslinking agent, curing agent, and deionized water;

[0036] The modified wollastonite includes a wollastonite core and a polymer layer disposed on the surface of the wollastonite core, the polymer layer including polydopamine.

[0037] The primer in this invention exhibits excellent performance through the synergistic effect of multiple materials. Firstly, the improved adhesive strength benefits from the combined action of modified wollastonite, waterborne polyurea resin, and a crosslinking agent. In this invention, dopamine hydrochloride is added to form a polymer layer with reactive structures such as catechol / quinone, amino, indole or indolequinone, and hydroxyl groups on the wollastonite surface; the mechanism is as follows... Figure 1 As shown, the polymer layer enhances the adhesion between wollastonite and the metal interface, improves the photothermal stability and UV resistance of the primer, and increases the suspending capacity of wollastonite to prevent sedimentation. The high polarity of the waterborne polyurea resin promotes physical or chemical bonding with the metal surface, further improving adhesion. The siloxane or silanol structure in the crosslinking agent bonds with the metal surface through secondary valence bonds or chemical bonds, further enhancing the adhesion strength between the primer and the substrate. Secondly, the thermal stability of the modified wollastonite plays a crucial role in durability and weather resistance. It not only improves the heat resistance and strength of the organic resin but also enhances the adaptability of the coating material under high temperature and stress conditions. The stable molecular structure and high crosslinking density of the waterborne polyurea resin enable the primer to maintain excellent weather resistance during long-term use. The hydrophobic layer formed by the crosslinking agent after drying effectively prevents moisture intrusion, solves the problem of interface detachment, and further enhances durability. Thirdly, the primer of this invention also exhibits excellent crack resistance. The combination of modified wollastonite and waterborne polyurea resin enhances the toughness and stability of the coating, preventing the cracking of epoxy resin under special environments, thus ensuring the adhesion of the primer. Fourthly, this invention uses deionized water as a solvent, avoiding the use of organic solvents and significantly reducing VOCs generation during the drying process, achieving the goal of green environmental protection.

[0038] In one specific embodiment, the components of the primer are as follows by weight:

[0039] The ingredients are: 30-45 parts waterborne epoxy resin, 15-30 parts waterborne polyurea resin, 3-10 parts modified wollastonite, 0.5-2 parts crosslinking agent, 10-20 parts curing agent, and 15-25 parts deionized water.

[0040] For example, the waterborne epoxy resin may be any value or a range of both of the following: 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, and 45 parts.

[0041] For example, the waterborne polyurea resin may be any value or a range of both of the following: 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, and 30 parts.

[0042] For example, the modified wollastonite may be any value of 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts, or a range of both.

[0043] For example, the crosslinking agent may be any value or a range of both of the following: 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, and 2 parts.

[0044] For example, the curing agent may be any value of 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, or 20 parts, or a range of both.

[0045] For example, the deionized water may be any value of 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, or 25 parts, or a range of both.

[0046] The weight range of each component ensures the comprehensive performance of the primer, making it suitable for various application scenarios and environmental conditions. The range of waterborne epoxy resins provides excellent adhesion and chemical resistance while maintaining the flexibility of the coating. The range of waterborne polyurea resins enhances the abrasion resistance and elasticity of the coating, making it suitable for various substrates. The range of modified wollastonite improves the mechanical strength and weather resistance of the coating. The range of crosslinking agents ensures the crosslinking density of the coating, thereby improving solvent resistance and heat resistance. The range of curing agents promotes the curing reaction of the resin, shortens the drying time, and enhances the hardness of the coating. The range of deionized water ensures the viscosity and flowability of the primer.

[0047] In one specific embodiment, the modified wollastonite is prepared by mixing wollastonite, dopamine hydrochloride solution, and metal salt solution.

[0048] Among them, dopamine hydrochloride can form a polydopamine coating on the surface of wollastonite, providing abundant active sites and enhancing the interfacial bonding with other materials. The introduction of metal salt solution can accelerate the oxidative polymerization of dopamine hydrochloride.

[0049] In the synthesis of polydopamine, metal salt solution acts as a catalyst to provide metal ions M. n+ This can accelerate the oxidative polymerization of dopamine hydrochloride, forming a highly adhesive polydopamine coating. The modification mechanism is as follows:

[0050] Oxidation stage:

[0051] Polymerization stage: Dopamine-quinone forms polydopamine through intermolecular reactions.

[0052] In metal ion Mn n+ Under catalysis, dopamine hydrochloride is first oxidized to dopamine-quinone, while metal ions are reduced ( Subsequently, dopamine quinone polymerizes gradually through intermolecular cyclization and cross-linking reactions, ultimately forming a dense and strongly adhesive polydopamine coating on the wollastonite surface. Polydopamine-modified wollastonite significantly enhances the interfacial compatibility between wollastonite and the organic matrix, improving the adhesion and dispersion stability of the primer. Simultaneously, metal ion doping introduces additional active sites, enhancing the coating's corrosion resistance and interfacial bonding strength, thereby optimizing the overall protective performance of the primer.

[0053] In one specific embodiment, the metal salt includes copper sulfate.

[0054] Among them, the aforementioned metal salts are readily available and inexpensive, making them an economical and efficient choice.

[0055] In one specific embodiment, the mass ratio of wollastonite, dopamine hydrochloride solution, and metal salt solution is 2:(10~20):1;

[0056] And / or, the concentration of the dopamine hydrochloride solution is 1~3 g / L;

[0057] And / or, the concentration of the metal salt solution is 1~2 g / L.

[0058] For example, the mass ratio of wollastonite, dopamine hydrochloride solution and metal salt solution can be any ratio of 2:10:1, 2:12:1, 2:14:1, 2:16:1, 2:18:1, 2:20:1 or any combination thereof.

[0059] For example, the concentration of the dopamine hydrochloride solution may be any value or a range of both, such as 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, 3 g / L.

[0060] For example, the concentration of the metal salt solution may be any value or a range of both of the following: 1 g / L, 1.2 g / L, 1.4 g / L, 1.5 g / L, 1.6 g / L, 1.8 g / L, 2 g / L.

[0061] The aforementioned mass ratio range ensures sufficient reaction between dopamine hydrochloride and the metal salt, forming a uniform and highly adhesive polydopamine coating. The concentration range of the dopamine hydrochloride solution provides enough dopamine monomer to support an effective polymerization reaction while avoiding uneven polymerization that might result from excessively high concentrations. The concentration of the metal salt solution ensures catalyst effectiveness, accelerates the oxidative polymerization process, and improves reaction efficiency and coating quality. These mass ratio and concentration ranges not only enhance the performance of the modified wollastonite but also ensure the economic efficiency and controllability of the production process.

[0062] In one specific embodiment, the method for preparing the polymer-modified wollastonite includes:

[0063] Adding 2000-5000 mesh wollastonite to a dopamine hydrochloride solution yields the first intermediate;

[0064] A metal salt solution was added to the first intermediate, and the mixture was stirred at 25°C for 1-3 hours. After filtration, washing, drying, and pulverization, the polymer-modified wollastonite was obtained.

[0065] This invention employs a step-by-step process to prepare polymer-modified wollastonite. First, 2000-5000 mesh wollastonite is added to a dopamine hydrochloride solution to form a first intermediate. This step ensures that dopamine molecules can fully contact and adsorb onto the wollastonite surface, forming a uniform coating. Subsequently, a metal salt solution is added to the first intermediate, and the mixture is stirred at 25°C for 1-3 hours. This process, through the catalytic effect of metal ions, accelerates the oxidative polymerization of dopamine, forming a dense and highly adhesive polydopamine coating. The step-by-step design avoids the uneven polymerization problems that may result from the simultaneous addition of dopamine hydrochloride and metal salt solutions, ensuring comprehensive coating of the wollastonite surface. This method improves the uniformity and stability of the dopamine coating, enhances the mechanical properties and chemical stability of the modified wollastonite, thereby improving the adhesion strength and weather resistance of the primer.

[0066] For example, the mesh size of the wollastonite may be any value of 2000 mesh, 3000 mesh, 4000 mesh, 5000 mesh, or a range of both.

[0067] High-mesh wollastonite has a small particle size and a large specific surface area, resulting in a larger contact area with dopamine. This facilitates more uniform coating and a more complete chemical reaction, thereby improving the modification effect. Moreover, after modification, it is easier to disperse evenly in the primer, reducing agglomeration, increasing interfacial bonding, which helps stress transfer and enhances mechanical properties. However, excessively fine particles may lead to increased interparticle adsorption, making dispersion more difficult.

[0068] Low-mesh wollastonite has a small specific surface area, which can easily prevent dopamine from completely covering the particle surface, leading to uneven modification or requiring an increase in the amount of dopamine. Moreover, large particles result in poor dispersibility, easily forming stress concentration points in the primer and reducing the performance of the composite material. In addition, low-mesh wollastonite has weak interfacial bonding, which may become a weak link in material failure. Therefore, the wollastonite mesh size selected in this invention is 2000~5000 mesh. Within this range, the modification effect of wollastonite is the best, thereby effectively improving the performance of the primer.

[0069] For example, the stirring time can be any value of 1h, 1.5h, 2h, 2.5h, 3h or a range of both.

[0070] The aforementioned stirring time range allows dopamine to be fully oxidized and polymerized under the catalysis of metal ions, forming a uniform polydopamine coating. This enhances the mechanical properties and chemical stability of the modified wollastonite, thereby improving the adhesion strength and weather resistance of the primer.

[0071] In one specific embodiment, the waterborne polyurea resin is a waterborne polyurethane urea dispersion and / or a waterborne aspartic polyurea resin emulsion.

[0072] Among them, the waterborne polyurethane urea dispersion provides excellent flexibility and abrasion resistance, enabling the primer to adapt to the surface stress and deformation of various substrates. The waterborne aspartic polyurea resin emulsion has rapid curing and excellent chemical resistance, improving the durability and corrosion resistance of the primer. The waterborne characteristics of these two resins ensure environmental friendliness and reduce the emission of volatile organic compounds. In addition, both the waterborne polyurethane urea dispersion and the waterborne aspartic polyurea resin emulsion have good compatibility and dispersibility, and can form a stable coating system with other components, thereby improving the convenience of construction and the overall performance of the primer.

[0073] In one specific embodiment, the crosslinking agent is at least one of polysiloxane powder, sodium methylsilicate, potassium methylsilicate, and sodium methylsiloxane.

[0074] Among these, the aforementioned crosslinking agents can effectively increase the crosslinking density of the primer, enhancing its mechanical strength and chemical resistance. The selection of these crosslinking agents not only improves the overall performance of the primer but also ensures its long-term stability and durability under various environmental conditions.

[0075] Secondly, the present invention provides a method for preparing the primer, comprising the following steps:

[0076] First, waterborne epoxy resin, waterborne polyurea resin and modified wollastonite are mixed and stirred. Then, crosslinking agent, curing agent and deionized water are added and stirring is continued to obtain the primer.

[0077] In some embodiments, waterborne epoxy resin, waterborne polyurea resin and modified wollastonite are first added to a reaction vessel and mechanically stirred for 15 to 30 minutes to obtain a mixture.

[0078] For example, the mechanical stirring time is any value or a range of both of the following: 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, and 30 min.

[0079] The specified mixing time range for the waterborne epoxy resin, waterborne polyurea resin, and modified wollastonite ensures thorough mixing of all components, forming a homogeneous matrix. This process facilitates the uniform dispersion of the modified wollastonite within the resin matrix, thereby enhancing the mechanical properties and adhesion of the primer.

[0080] In some embodiments, a crosslinking agent, a curing agent, and deionized water are added to the mixture, and the mixture is mechanically stirred for 15 to 30 minutes to obtain a primer.

[0081] For example, the mechanical stirring time is any value or a range of both of the following: 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, and 30 min.

[0082] The range of stirring time after adding the crosslinking agent, curing agent, and deionized water ensures that these components are evenly distributed in the mixture, promoting the full progress of the crosslinking reaction. This stirring process further ensures the chemical stability and durability of the primer.

[0083] Thirdly, the present invention provides the use of the primer or the primer prepared by the method described herein as an adhesive.

[0084] The primer in this invention can be used as an adhesive. Its excellent adhesion ensures a strong bond on inert substrates such as metal and glass. Furthermore, due to the introduction of modified wollastonite, the primer of this invention also has good durability, weather resistance, and crack resistance.

[0085] Example 1

[0086] Primer components: 40 parts waterborne epoxy resin, 25 parts waterborne aspartic polyurea resin emulsion, 6 parts modified wollastonite, 1 part sodium methylsilicate, 18 parts dimethylethanolamine, and 15 parts deionized water.

[0087] 100g of wollastonite (2000 mesh) was added to 500g of a 3g / L dopamine hydrochloride solution, followed by 25g of a 2g / L CuSO4 solution. The mixture was stirred at room temperature for 1 hour, filtered, washed with deionized water, dried, and pulverized to obtain modified wollastonite. 40 parts of waterborne epoxy resin, 25 parts of waterborne aspartic polyurea resin emulsion, and 6 parts of modified wollastonite were added to a reaction vessel and mechanically stirred for 15 minutes to obtain a mixture. 1 part of sodium methylsilicate, 18 parts of dimethylethanolamine, and 15 parts of deionized water were added to the mixture, and the mixture was mechanically stirred for 30 minutes to obtain a primer.

[0088] Example 2

[0089] Primer components: 45 parts waterborne epoxy resin, 30 parts waterborne polyurethane urea dispersion, 3 parts modified wollastonite, 0.5 parts polysiloxane, 20 parts triethanolamine, and 20 parts deionized water.

[0090] 100g of wollastonite (5000 mesh) was added to 1000g of a 2g / L dopamine hydrochloride solution, followed by 100g of a 1g / L CuSO4 solution. The mixture was stirred at room temperature for 3 hours, filtered, washed with deionized water, dried, and pulverized to obtain modified wollastonite. 45 parts of waterborne epoxy resin, 30 parts of waterborne polyurethane urea dispersion, and 3 parts of modified wollastonite were added to a reaction vessel and mechanically stirred for 30 minutes to obtain a mixture. 0.5 parts of polysiloxane powder, 20 parts of triethanolamine, and 20 parts of deionized water were added to the mixture, and the mixture was mechanically stirred for 20 minutes to obtain a primer.

[0091] Example 3

[0092] Primer components: 30 parts waterborne epoxy resin, 28 parts waterborne aspartic polyurea resin emulsion, 8 parts modified wollastonite, 2 parts potassium methylsilicate, 12 parts dimethylformamide, and 16 parts deionized water.

[0093] 100g of wollastonite (4000 mesh) was added to 750g of a 2g / L dopamine hydrochloride solution, followed by 55g of a 1.2g / L CuSO4 solution. The mixture was stirred at room temperature for 2 hours, filtered, washed with deionized water, dried, and pulverized to obtain modified wollastonite. 30 parts of waterborne epoxy resin, 28 parts of waterborne aspartic polyurea resin emulsion, and 8 parts of modified wollastonite were added to a reaction vessel and mechanically stirred for 25 minutes to obtain a mixture. 2 parts of potassium methylsilicate, 12 parts of dimethylformamide, and 16 parts of deionized water were added to the mixture, and the mixture was mechanically stirred for 20 minutes to obtain a primer.

[0094] Comparative Example 1

[0095] The difference from Example 1 is that this comparative example does not include modified wollastonite, waterborne aspartic polyurea resin emulsion, and crosslinking agent, while the proportions of other components and the steps remain unchanged, resulting in a primer.

[0096] Comparative Example 2

[0097] The difference from Example 1 is that no modified wollastonite is added in this comparative example, while the proportions of the remaining components and the steps remain unchanged, resulting in a primer.

[0098] Comparative Example 3

[0099] The difference from Example 1 is that this comparative example does not include water-based aspartic polyurea resin emulsion, while the proportions of other components and the steps remain unchanged, resulting in a primer.

[0100] Comparative Example 4

[0101] The difference from Example 1 is that sodium methylsilicate is not added in this comparative example, while the proportions of the remaining components and the steps remain unchanged, resulting in a primer.

[0102] Comparative Example 5

[0103] The difference from Example 1 is that the wollastonite added in this comparative example is not modified with dopamine, while the proportions and steps of the other components remain unchanged, resulting in a primer.

[0104] Test case

[0105] Cracking condition: The primers prepared in Examples 1-3 and Comparative Examples 1-5 were applied to a clean and dry aluminum surface and heated to dry to form a coating. The surface cracks were observed and the results were recorded in Table 1.

[0106] Peel test:

[0107] 1. After the coating surface dries, apply Sika265 polyurethane sealant and cure it under standard conditions (temperature 23±2℃, humidity 50±5%RH). Then, perform a peel test on the sample and determine the bonding percentage by the proportion of cohesive failure area. The test results are recorded in Table 1.

[0108] 2. The samples cured under standard conditions were subjected to stress vibration test. The vibration parameters were set according to GB / T 21563 to simulate the vibration environment under actual working conditions. After the test was completed, the samples were subjected to peel test. The bonding performance was evaluated by the proportion of cohesive failure area. The test results were recorded in Table 1.

[0109] 3. The samples cured under standard conditions were placed in a 70℃ / 95%RH environment for temperature and humidity testing for 300 hours, during which the surface condition of the samples was observed regularly. After the test, the samples were subjected to a peel test, and the bonding performance was evaluated by the proportion of cohesive failure area. The test results are recorded in Table 1.

[0110] 4. Samples cured under standard conditions were subjected to accelerated aging tests under artificial climate conditions, simulating natural environmental aging conditions, for 2000 hours, during which the surface condition of the samples was observed periodically. After the aging test, peel tests were performed on the samples, and the bonding performance was evaluated by the proportion of cohesive failure area. The test results are recorded in Table 1. The aging test results of Example 1 and Comparative Example 1 are as follows. Figure 2 , Figure 3 As shown.

[0111] Table 1

[0112]

[0113] As can be seen from the test results in Table 1, the primers of Examples 1 to 3 all exhibited excellent performance under various test conditions, with no cracking, and achieved 100% cohesive failure (CF) under all test conditions, indicating that they have extremely high adhesive strength and stability.

[0114] Comparative Example 1 exhibited severe cracking and interfacial peeling (AF) under all test conditions, indicating that the lack of modified wollastonite, waterborne aspartic polyurea resin emulsion, and crosslinking agent severely affected the integrity and adhesion of the coating. Comparative Examples 2 and 3, although not severely cracked, showed significantly inferior adhesion performance compared to the Example, especially in vibration, temperature and humidity, and aging tests, where the cohesive failure rate decreased significantly, indicating that the absence of modified wollastonite and waterborne aspartic polyurea resin emulsion weakened the coating's durability and adhesion strength. Comparative Example 4 did not exhibit cracking, but the cohesive failure rate was significantly reduced in the temperature and humidity test, reaching only 28% CF, indicating that the lack of crosslinking agent had a significant impact on the coating's moisture resistance. Comparative Example 5 showed slight cracking under all test conditions, and the cohesive failure rate was lower than that of the Example in all tests, especially in vibration and temperature and humidity tests, indicating that wollastonite without dopamine modification could not provide sufficient adhesion strength and stability. The experimental data above show that the combination of modified wollastonite, waterborne aspartic polyurea resin emulsion, and crosslinking agent has a significant effect on improving the adhesion and durability of the primer.

[0115] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0116] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A primer, characterized in that, The primer comprises the following components: Waterborne epoxy resin, waterborne polyurea resin, modified wollastonite, crosslinking agent, curing agent, and deionized water; The modified wollastonite includes a wollastonite core and a polymer layer disposed on the surface of the wollastonite core, the polymer layer including polydopamine.

2. The primer according to claim 1, characterized in that, The components of the primer are as follows by weight: The ingredients are: 30-45 parts waterborne epoxy resin, 15-30 parts waterborne polyurea resin, 3-10 parts modified wollastonite, 0.5-2 parts crosslinking agent, 10-20 parts curing agent, and 15-25 parts deionized water.

3. The primer according to claim 1, characterized in that, The modified wollastonite is prepared by mixing wollastonite, dopamine hydrochloride solution and metal salt solution.

4. The primer according to claim 3, characterized in that, The metal salt includes copper sulfate.

5. The primer according to claim 3, characterized in that, The mass ratio of the wollastonite, dopamine hydrochloride solution, and metal salt solution is 2:(10~20):1; And / or, the concentration of the dopamine hydrochloride solution is 1~3 g / L; And / or, the concentration of the metal salt solution is 1~2 g / L.

6. The primer according to any one of claims 1 to 5, characterized in that, The method for preparing polymer-modified wollastonite includes: Adding 2000-5000 mesh wollastonite to a dopamine hydrochloride solution yields the first intermediate; A metal salt solution was added to the first intermediate, and the mixture was stirred at 25°C for 1-3 hours. After filtration, washing, drying, and pulverization, the polymer-modified wollastonite was obtained.

7. The primer according to claim 1, characterized in that, The waterborne polyurea resin is a waterborne polyurethane urea dispersion and / or a waterborne aspartic polyurea resin emulsion.

8. A primer according to claim 1, characterized in that, The crosslinking agent is at least one of polysiloxane powder, sodium methylsilicate, potassium methylsilicate, and sodium methylsiloxane.

9. A primer according to claim 1, characterized in that, The curing agent is at least one of diethanolamine, triethanolamine, dimethylethanolamine, and dimethylformamide.

10. A method for preparing a primer as described in any one of claims 1 to 9, characterized in that, Includes the following steps: First, waterborne epoxy resin, waterborne polyurea resin and modified wollastonite are mixed and stirred. Then, crosslinking agent, curing agent and deionized water are added and stirring is continued to obtain the primer.

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