Oil paint resistant to salt mist erosion and preparation method thereof

Abstract

The invention relates to the technical field of paint, in particular to salt mist corrosion resistant paint and a preparation method thereof.In conclusion, the salt mist corrosion resistant paint comprises the following components: a resin base material: water-based acrylic acid modified epoxy resin and water-based polyurethane; the composite filler is prepared by coating zinc phosphate and diatomite with nano silicon dioxide; functional aids: a polyether modified organic silicon defoaming agent and a polycarboxylic acid ammonium salt dispersing agent; a solvent system: deionized water and propylene glycol monomethyl ether; according to the invention, the problems of poor salt mist resistance, insufficient environmental protection property and the like of the existing paint are solved, through scientific component design and process optimization, the paint can still keep good adhesive force, impact resistance and compactness in a high salt mist environment, and the service life of a base material is greatly prolonged. Meanwhile, VOC emission is reduced by adopting a water-based system, functionality and environmental friendliness are both considered, and the water-based paint is suitable for severe environments such as ocean engineering and chemical equipment and has important practical value and popularization prospects.

Description

Technical Field

[0001] This invention relates to the field of paint technology, specifically to a paint resistant to salt spray corrosion and its preparation method. Background Technology

[0002] Paint, as a functional coating material, is widely used in metal and construction industries. By forming a protective film on the surface of the substrate, it serves to prevent corrosion, provide decoration, and extend service life. In high-salt-spray environments such as marine and chemical plants, the paint's resistance to salt spray corrosion is particularly critical, directly affecting the durability of the substrate.

[0003] Existing paints generally suffer from insufficient salt spray resistance: traditional anti-corrosion fillers (such as ordinary zinc phosphate) are prone to agglomeration and difficult to disperse evenly in the coating, allowing corrosive media (such as chloride ions and moisture) to easily penetrate into the substrate through pores; resin bases have low crosslinking density, poor water resistance and compactness, and are prone to blistering and peeling when exposed to salt spray environments for a long time; some solvent-based paints, although having good corrosion resistance, have high volatile organic compound (VOC) content, which does not meet environmental protection requirements. These defects limit the application of paints in highly corrosive environments. Summary of the Invention

[0004] The purpose of this invention is to provide a paint that is resistant to salt spray corrosion.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A paint resistant to salt spray corrosion, comprising the following components by weight: Resin base: 30-40 parts of waterborne acrylic modified epoxy resin and 20-25 parts of waterborne polyurethane; Composite filler: 8-12 parts of nano-silica-coated zinc phosphate and 5-8 parts of diatomaceous earth, wherein the nano-silica-coated zinc phosphate has a core-shell structure and a particle size of 50-80 nm; Functional additives: 0.2-0.5 parts of polyether-modified silicone defoamer and 0.5-1.0 parts of polycarboxylate ammonium salt dispersant; Solvent system: 15-25 parts deionized water and 5-10 parts propylene glycol methyl ether.

[0006] As a further technical solution, the method for preparing the waterborne acrylic modified oxygen resin is as follows: (1) The acrylic monomer and epoxy resin are reacted at 80°C for 3 hours in the presence of potassium persulfate in the presence of an initiator, according to a weight ratio of 1:4-6, to generate acrylic modified epoxy resin. The amount of potassium persulfate used is 1-3% of the total weight of acrylic monomer and epoxy resin; (2) Isophorone diisocyanate was added at a weight ratio of 1:8-10 to acrylic modified epoxy resin, and reacted at 60°C for 2 hours under nitrogen protection to form an epoxy-polyurethane crosslinking network.

[0007] As a further technical solution, the acrylic monomer in step (1) is methacrylic acid or butyl acrylate.

[0008] As a further technical solution, the method for preparing the nano-silica-coated zinc phosphate is as follows: ① Disperse zinc phosphate and deionized water in deionized water at a solid-liquid ratio of 1:8-1:12, add 5-8wt% of silane coupling agent KH-550 hydrolysate, and sonicate at 300-500W power for 30 minutes. ② Add tetraethyl orthosilicate ethanol solution dropwise at a weight ratio of 1:3-5 to tetraethyl orthosilicate and stir at 60°C for 4 hours to form a silica coating layer; ③ After centrifugation and washing, dry at 80-100℃ for 6-8 hours to obtain core-shell structured fillers with a particle size of 50-80nm.

[0009] As a further technical solution, the preparation method of the silane coupling agent KH-550 hydrolysate in step ① is as follows: KH-550 and deionized water are mixed at a volume ratio of 1:5-8, acetic acid is added to adjust the pH to 3.5-4.5, and the mixture is stirred at room temperature for 30 minutes to obtain the solution.

[0010] As a further technical solution, the concentration of the tetraethyl orthosilicate ethanol solution in step ② is 20-30 wt%.

[0011] As a further technical solution, the waterborne polyurethane is a self-emulsifying anionic waterborne polyurethane with a solid content of 35-45 wt% and a number-average molecular weight of 8000-15000 g / mol.

[0012] A method for preparing a paint resistant to salt spray corrosion includes the following steps: (1) Preparation of composite fillers; (2) Preparation of resin base material; (3) Preparation of paint: Add the resin base, composite filler, polycarboxylate ammonium salt dispersant, and polyether modified silicone defoamer to a high-speed mixer according to the respective weight parts, and premix at 1200 rpm for 10-15 minutes; Grind to a fineness of 20-30μm, add the corresponding weight parts of deionized water and propylene glycol methyl ether, continue stirring for 30-40 minutes, and filter through a 100-150 mesh screen to obtain the finished product.

[0013] As a further technical solution, in step (3), a sand mill is used for grinding, the grinding media is zirconia beads with a particle size of 0.8-1.0 mm, and the grinding speed is 800 r / min.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention significantly improves the salt spray erosion resistance and overall performance of paint by optimizing component formulation and preparation process, specifically in the following ways: Each component has a clearly defined function and a significant synergistic effect: In the resin base, waterborne acrylic modified epoxy resin and waterborne polyurethane form an interpenetrating cross-linked network, combining the high adhesion of epoxy resin and the flexibility of polyurethane, thus improving the density of the coating; In the composite filler, nano-silica coated zinc phosphate (core-shell structure) not only physically blocks corrosive media through the silica shell layer, but also inhibits metal corrosion through the corrosion inhibition effect of zinc phosphate; the porous structure of diatomaceous earth can adsorb moisture and enhance the mechanical strength of the coating; Functional additives ensure uniform dispersion and no bubbles in the system, and the solvent system takes into account both environmental protection and film-forming properties.

[0015] The paint prepared by this invention forms a multi-protection system with physical barrier, chemical corrosion inhibition and structural reinforcement by cross-linking network and core-shell filler: cross-linking network reduces coating porosity, core-shell filler fills micro-defects and releases corrosion-inhibiting components, and additives and solvents ensure the stability of the synergistic effect of each component, ultimately achieving long-term protection of the coating in salt spray environment.

[0016] In summary, this invention solves the problems of poor salt spray resistance and insufficient environmental friendliness of existing paints. Through scientific component design and process optimization, the paint maintains good adhesion, impact resistance, and density even in high salt spray environments, significantly extending the service life of the substrate. Simultaneously, the use of a water-based system reduces VOC emissions, balancing functionality and environmental friendliness. It is suitable for harsh environments such as marine engineering and chemical equipment, possessing significant practical value and promising prospects for widespread application. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention provides a paint resistant to salt spray corrosion. Through specific component combinations and preparation processes, a dense coating with strong adhesion and excellent salt spray resistance can be formed. The paint of this invention, by weight, comprises a resin base, composite filler, functional additives, and a solvent system. Its preparation method includes three main steps: composite filler preparation, resin base preparation, and paint formulation.

[0019] 1. Resin base material The resin base materials include waterborne acrylic-modified epoxy resin and waterborne polyurethane, wherein: The waterborne acrylic-modified epoxy resin is preferably 30-40 parts by weight, more preferably 32-38 parts; its preparation method is as follows: (1) The acrylic monomer and epoxy resin are reacted at 80°C for 3 hours in the presence of potassium persulfate in the presence of potassium persulfate as an initiator, with a weight ratio of 1:4-6, more preferably 1:5, to generate acrylic modified epoxy resin; the amount of potassium persulfate is 1-3% of the total weight of acrylic monomer and epoxy resin, more preferably 2%; the acrylic monomer is preferably methacrylic acid or butyl acrylate.

[0020] (2) Isophorone diisocyanate is added at a weight ratio of 1:8-10, more preferably 1:9, to acrylic modified epoxy resin. The mixture is reacted at 60°C for 2 hours under nitrogen protection to form an epoxy-polyurethane crosslinking network and improve the density of the coating.

[0021] The waterborne polyurethane is preferably 20-25 parts by weight, more preferably 21-24 parts; it is preferably a self-emulsifying anionic waterborne polyurethane with a solid content of 35-45 wt%, more preferably 38-42 wt%, and a number average molecular weight of 8000-15000 g / mol, more preferably 10000-12000 g / mol.

[0022] 2. Composite packing The composite filler consists of nano-silica coated zinc phosphate and diatomaceous earth, wherein: The preferred weight percentage of nano-silica-coated zinc phosphate is 8-12 parts, more preferably 9-11 parts, with a core-shell structure and a particle size of 50-80 nm, more preferably 60-70 nm. The preparation method is as follows: ① Disperse zinc phosphate and deionized water at a solid-liquid ratio of 1:8-1:12, more preferably 1:10, add 5-8wt%, more preferably 6wt%, of silane coupling agent KH-550 hydrolysate, and sonicate at 300-500W, more preferably 400W for 30 minutes; The preparation method of the KH-550 hydrolysate is as follows: mix KH-550 and deionized water at a volume ratio of 1:5-8, more preferably 1:6, add acetic acid to adjust the pH to 3.5-4.5, more preferably 4.0, and stir at room temperature for 30 minutes.

[0023] ② Add ethanol solution of tetraethyl orthosilicate at a weight ratio of 1:3-5, more preferably 1:4, with a concentration of 20-30wt%, more preferably 25wt%, and stir at 60°C for 4 hours to form a silica coating layer.

[0024] ③ After centrifugal washing, dry at 80-100℃, more preferably 90℃, for 6-8 hours, more preferably 7 hours, to obtain the target packing.

[0025] The preferred weight of diatomaceous earth is 5-8 parts, more preferably 6-7 parts, as its porous structure can help improve the air permeability and mechanical strength of the coating.

[0026] 3. Functional additives Polyether-modified silicone defoamer: preferably 0.2-0.5 parts by weight, more preferably 0.3-0.4 parts by weight, can eliminate bubbles generated during the preparation process and avoid coating defects.

[0027] Ammonium polycarboxylate dispersant: preferably 0.5-1.0 parts by weight, more preferably 0.6-0.8 parts by weight, which can improve the dispersibility of fillers and prevent agglomeration.

[0028] 4. Solvent System Deionized water: preferably 15-25 parts by weight, more preferably 18-22 parts by weight, as the main dispersion medium, is environmentally friendly and has no volatile toxicity.

[0029] Propylene glycol methyl ether: preferably 5-10 parts by weight, more preferably 6-8 parts by weight, can adjust the viscosity of the coating and improve film-forming properties.

[0030] 5. Paint preparation method (1) Preparation of composite filler: Prepare nano-silica coated zinc phosphate according to the above method, and mix it with diatomaceous earth for later use.

[0031] (2) Resin base material preparation: Waterborne acrylic modified epoxy resin is prepared according to the above method and mixed with waterborne polyurethane for later use.

[0032] (3) Paint preparation: Add the resin base, composite filler, polycarboxylate ammonium salt dispersant, and polyether modified silicone defoamer to a high-speed mixer according to the respective weight parts, and premix at 1200 rpm for 10-15 minutes, more preferably 12 minutes; Grinding is performed using a sand mill (grinding media consisting of zirconia beads with a particle size of 0.8-1.0 mm, grinding speed 800 r / min) to a fineness of 20-30 μm, more preferably 25 μm; Add the corresponding weight parts of deionized water and propylene glycol methyl ether, and continue stirring for 30-40 minutes, more preferably 35 minutes. Filter using a 100-150 mesh filter, more preferably 120 mesh, to obtain the finished product.

[0033] In the following examples, the acrylic monomer of the waterborne acrylic-modified epoxy resin is methacrylic acid, the waterborne polyurethane is a self-emulsifying anionic waterborne polyurethane (solid content 40wt%, number average molecular weight 11000g / mol), the polyether-modified silicone defoamer is commercially available BYK-024, and the polycarboxylate ammonium salt dispersant is commercially available SN-5040. Example 1

[0034] Resin base: 35 parts waterborne acrylic modified epoxy resin, 22 parts waterborne polyurethane; Composite filler: 10 parts nano-silica coated zinc phosphate (particle size 60nm), 6 parts diatomaceous earth; Functional additives: 0.3 parts polyether-modified silicone defoamer, 0.7 parts polycarboxylate ammonium salt dispersant; Solvent system: 20 parts deionized water, 7 parts propylene glycol methyl ether; Preparation method: (1) Preparation of composite filler: Prepare nano-silica coated zinc phosphate according to the above method, and mix it with diatomaceous earth for later use.

[0035] (2) Resin base material preparation: Waterborne acrylic modified epoxy resin is prepared according to the above method and mixed with waterborne polyurethane for later use.

[0036] (3) Paint preparation: Add the resin base, composite filler, polycarboxylate ammonium salt dispersant, and polyether modified silicone defoamer to a high-speed mixer according to the respective weight parts, and premix at 1200 rpm for 12 minutes; The material was ground to a fineness of 25 μm using a sand mill; the grinding media were zirconia beads with a particle size of 1.0 mm, and the grinding speed was 800 r / min. Add the corresponding weight parts of deionized water and propylene glycol methyl ether, continue stirring for 35 minutes, and filter through a 120-mesh filter to obtain the finished product. Example 2

[0037] Resin base: 32 parts waterborne acrylic modified epoxy resin, 24 parts waterborne polyurethane; Composite filler: 8 parts nano-silica coated zinc phosphate (particle size 50nm), 8 parts diatomaceous earth; Functional additives: 0.2 parts polyether-modified silicone defoamer, 1.0 part polycarboxylate ammonium salt dispersant; Solvent system: 15 parts deionized water, 10 parts propylene glycol methyl ether; Preparation method: (1) Preparation of composite filler: Prepare nano-silica coated zinc phosphate according to the above method, and mix it with diatomaceous earth for later use.

[0038] (2) Resin base material preparation: Waterborne acrylic modified epoxy resin is prepared according to the above method and mixed with waterborne polyurethane for later use.

[0039] (3) Paint preparation: Add the resin base, composite filler, polycarboxylate ammonium salt dispersant, and polyether modified silicone defoamer to a high-speed mixer according to the respective weight parts, and premix at 1200 rpm for 12 minutes; The material was ground to a fineness of 25 μm using a sand mill; the grinding media were zirconia beads with a particle size of 1.0 mm, and the grinding speed was 800 r / min. Add the corresponding weight parts of deionized water and propylene glycol methyl ether, continue stirring for 35 minutes, and filter through a 120-mesh filter to obtain the finished product. Example 3

[0040] Resin base: 38 parts waterborne acrylic modified epoxy resin, 20 parts waterborne polyurethane; Composite filler: 12 parts nano-silica coated zinc phosphate (particle size 80nm), 5 parts diatomaceous earth; Functional additives: 0.5 parts polyether-modified silicone defoamer, 0.5 parts polycarboxylate ammonium salt dispersant; Solvent system: 25 parts deionized water, 5 parts propylene glycol methyl ether; Preparation method: (1) Preparation of composite filler: Prepare nano-silica coated zinc phosphate according to the above method, and mix it with diatomaceous earth for later use.

[0041] (2) Resin base material preparation: Waterborne acrylic modified epoxy resin is prepared according to the above method and mixed with waterborne polyurethane for later use.

[0042] (3) Paint preparation: Add the resin base, composite filler, polycarboxylate ammonium salt dispersant, and polyether modified silicone defoamer to a high-speed mixer according to the respective weight parts, and premix at 1200 rpm for 12 minutes; The material was ground to a fineness of 25 μm using a sand mill; the grinding media were zirconia beads with a particle size of 1.0 mm, and the grinding speed was 800 r / min. Add the corresponding weight parts of deionized water and propylene glycol methyl ether, continue stirring for 35 minutes, and filter through a 120-mesh filter to obtain the finished product. Example 4

[0043] Resin base: 30 parts waterborne acrylic modified epoxy resin, 25 parts waterborne polyurethane; Composite filler: 9 parts nano-silica coated zinc phosphate (particle size 55nm), 7 parts diatomaceous earth; Functional additives: 0.4 parts polyether-modified silicone defoamer, 0.6 parts polycarboxylate ammonium salt dispersant; Solvent system: 18 parts deionized water, 8 parts propylene glycol methyl ether; Preparation method: (1) Preparation of composite filler: Prepare nano-silica coated zinc phosphate according to the above method, and mix it with diatomaceous earth for later use.

[0044] (2) Resin base material preparation: Waterborne acrylic modified epoxy resin is prepared according to the above method and mixed with waterborne polyurethane for later use.

[0045] (3) Paint preparation: Add the resin base, composite filler, polycarboxylate ammonium salt dispersant, and polyether modified silicone defoamer to a high-speed mixer according to the respective weight parts, and premix at 1200 rpm for 12 minutes; The material was ground to a fineness of 25 μm using a sand mill; the grinding media were zirconia beads with a particle size of 1.0 mm, and the grinding speed was 800 r / min. Add the corresponding weight parts of deionized water and propylene glycol methyl ether, continue stirring for 35 minutes, and filter through a 120-mesh filter to obtain the finished product. Example 5

[0046] Resin base: 40 parts waterborne acrylic modified epoxy resin, 21 parts waterborne polyurethane; Composite filler: 11 parts nano-silica coated zinc phosphate (particle size 70nm), 6 parts diatomaceous earth; Functional additives: 0.3 parts polyether-modified silicone defoamer, 0.8 parts polycarboxylate ammonium salt dispersant; Solvent system: 22 parts deionized water, 6 parts propylene glycol methyl ether; Preparation method: (1) Preparation of composite filler: Prepare nano-silica coated zinc phosphate according to the above method, and mix it with diatomaceous earth for later use.

[0047] (2) Resin base material preparation: Waterborne acrylic modified epoxy resin is prepared according to the above method and mixed with waterborne polyurethane for later use.

[0048] (3) Paint preparation: Add the resin base, composite filler, polycarboxylate ammonium salt dispersant, and polyether modified silicone defoamer to a high-speed mixer according to the respective weight parts, and premix at 1200 rpm for 12 minutes; The material was ground to a fineness of 25 μm using a sand mill; the grinding media were zirconia beads with a particle size of 1.0 mm, and the grinding speed was 800 r / min. Add the corresponding weight parts of deionized water and propylene glycol methyl ether, continue stirring for 35 minutes, and filter through a 120-mesh filter to obtain the finished product.

[0049] The following is a comparative example. Comparative Example 1 The difference from Example 1 is that the composite filler is 16 parts diatomaceous earth (without nano-silica coated zinc phosphate), while the other components and preparation methods are the same.

[0050] Comparative Example 2 The difference from Example 1 is that the resin base is 57 parts of waterborne polyurethane (anhydrous acrylic modified epoxy resin), while the other components and preparation methods are the same.

[0051] test Experiment 1: Neutral Salt Spray Test Test standard: Refer to GB / T10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test"; Test method: Place the cold-rolled steel plate test plate coated with paint (dry film thickness 50±5μm) in a salt spray chamber and spray it continuously with 5% (mass fraction) NaCl solution (pH 6.5-7.2) at 35℃. Observe the time (hours) when the test plate shows rust (area > 5%) or blistering (grade > 2). Each group of tests had 3 parallel samples, and the results were averaged. The results are as follows:

[0052] As shown in Table 1, the salt spray tolerance times of Examples 1-5 were significantly higher than those of the comparative examples, indicating that the formulation and process of the present invention can effectively improve salt spray resistance. Comparative Example 1 lacked nano-silica-coated zinc phosphate, resulting in the loss of the physical barrier (silica shell) and chemical corrosion inhibition (zinc phosphate) effects of its core-shell structure. Corrosive media (Cl⁻, H₂O) easily penetrated into the substrate, leading to a significant decrease in salt spray resistance. Comparative Example 2, due to its anhydrous acrylic-modified epoxy resin, lacked an epoxy-polyurethane crosslinking network, resulting in insufficient coating density. Corrosive media easily penetrated through the pores, reducing salt spray resistance.

[0053] Experiment 2: Adhesion Test (Cross-cut Test) Test standard: Refer to GB / T 9286-2021 "Cross-cut test for paint and varnish film"; Test method: Use a blade to make 10×10 grids (1mm×1mm per grid) on the painted test board, down to the substrate. Apply 3M tape (model 600) and then quickly peel it off. Rate the area of ​​grid peeling off (0: no peeling; 5: all peeling off). Each group of tests had 3 parallel samples, and the results were averaged. The results are as follows:

[0054] As shown in Table 2, the adhesion grades of Examples 1-5 are 0-1, indicating that the coatings are firmly bonded to the substrate. Comparative Example 1, lacking nano-silica-coated zinc phosphate, suffers from decreased interfacial compatibility between the filler and resin matrix, and the absence of chemical anchoring effect from zinc phosphate, resulting in reduced adhesion. Comparative Example 2, lacking an epoxy-polyurethane crosslinking network, exhibits weaker bonding between the resin matrix and the substrate, leading to a lower adhesion grade.

[0055] Test 3: Impact Resistance Test Test standard: Refer to GB / T 1732-2020 "Test Method for Impact Resistance of Coating Film"; Test method: Use an impact testing machine (1kg hammer) to drop from different heights to impact the paint-coated test panel (back coating), and record the maximum impact height (cm) from which the coating does not crack or peel off, and convert it into impact strength (cm·kg). Each group of tests had 3 parallel samples, and the results were averaged. The results are as follows:

[0056] As shown in Table 3, the impact resistance of Examples 1-5 is significantly better than that of the comparative examples, indicating that the coating of the present invention has better toughness. In Comparative Example 1, the lack of nano-silica-coated zinc phosphate resulted in the disappearance of the reinforcing effect of the silica shell, leading to increased brittleness of the coating. In Comparative Example 2, the absence of an epoxy-polyurethane crosslinking network resulted in insufficient elasticity of the resin base, leading to a decrease in impact resistance.

[0057] In summary, this invention, through specific component combinations, especially the synergistic effect of nano-silica-coated zinc phosphate and epoxy-polyurethane crosslinking network, and specific process parameters, can prepare paints with excellent salt spray erosion resistance, strong adhesion, and good toughness, suitable for metal protection in highly corrosive environments.

[0058] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A salt spray resistant paint, characterized by, By weight parts, including the following components: Resin base: 30-40 parts of water-based acrylic modified epoxy resin and 20-25 parts of water-based polyurethane; Composite filler: 8-12 parts of nano-silicon dioxide coated zinc phosphate and 5-8 parts of diatomite, the nano-silicon dioxide coated zinc phosphate is core-shell structure, particle size is 50-80 nm; Functional auxiliary agent: 0.2-0.5 parts of polyether modified silicone defoamer and 0.5-1.0 parts of polycarboxylic acid ammonium salt dispersant; Solvent system: 15-25 parts of deionized water and 5-10 parts of propylene glycol methyl ether.

2. The salt-fog resistant paint according to claim 1, characterized by, The preparation method of the water-based acrylic modified epoxy resin is: (1) The acrylic monomer and the epoxy resin are reacted at 80 DEG C for 3 hours in the presence of initiator potassium persulfate with the weight ratio of 1:4-6, to generate acrylic modified epoxy resin; The amount of potassium persulfate is 1-3% of the total weight of acrylic monomer and epoxy resin; (2) Isophorone diisocyanate is added with the weight ratio of 1:8-10, and isophorone diisocyanate is reacted at 60 DEG C for 2 hours under nitrogen protection, to form an epoxy-polyurethane crosslinking network.

3. The salt-fog resistant paint according to claim 2, characterized in that, The acrylic monomer in step (1) is methyl methacrylate or butyl acrylate.

4. The salt-fog resistant paint according to claim 1, characterized by, The preparation method of the nano-silicon dioxide coated zinc phosphate is: ① Zinc phosphate and deionized water are dispersed in deionized water with the solid-liquid ratio of 1:8-1:12, 5-8wt% silane coupling agent KH-550 hydrolysate is added, and ultrasonic treatment is carried out at 300-500W power for 30 minutes; ② Tetraethyl orthosilicate ethanol solution is added with the weight ratio of 1:3-5, and stirring reaction is carried out at 60 DEG C for 4 hours to form a silica coating layer; ③ After centrifugal washing, drying is carried out at 80-100 DEG C for 6-8 hours to obtain core-shell structure filler with particle size of 50-80 nm.

5. The salt-fog resistant paint according to claim 4, characterized in that, The preparation method of the silane coupling agent KH-550 hydrolysate in step ① is: KH-550 and deionized water are mixed with the volume ratio of 1:5-8, acetic acid is added to adjust pH to 3.5-4.5, stirring is carried out at room temperature for 30 minutes, and then KH-550 hydrolysate is obtained.

6. The salt-fog resistant paint according to claim 4, characterized by, The concentration of the tetraethyl orthosilicate ethanol solution in step ② is 20-30wt%.

7. The salt-fog resistant paint according to claim 1, characterized by, The water-based polyurethane is self-emulsifying anionic water-based polyurethane, the solid content is 35-45wt%, and the number average molecular weight is 8000-15000g / mol.

8. A method of preparing a salt-fog resistant paint according to any one of claims 1 to 7, characterized in that, Including the following steps: (1) Preparation of composite filler; (2) Preparation of resin base; (3) Preparation of paint: The resin base, composite filler, polycarboxylic acid ammonium salt dispersant and polyether modified silicone defoamer are added into a high-speed stirrer according to the weight parts, and pre-mixed for 10-15 minutes at 1200 rpm; Grinding to fineness of 20-30μm, adding corresponding weight parts of deionized water and propylene glycol methyl ether, and continuing to stir for 30-40min, then filtering with 100-150 mesh filter screen to obtain finished product.

9. The production method according to claim 8, characterized by, The grinding in step (3) adopts sand mill, the grinding medium is zirconia bead with particle size of 0.8-1.0mm, and the grinding speed is 800r / min.

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