Polishing-free water-based epoxy finish paint for aluminum parts and electroplated parts and preparation method of polishing-free water-based epoxy finish paint

Abstract

The invention relates to the technical field of coatings, and particularly discloses a polishing-free waterborne epoxy finish paint for aluminum parts and electroplated parts, which comprises a material A and a material B, the material A is prepared from the following components in parts by weight: 480 to 570 parts of epoxy emulsion, 3 to 7 parts of a defoaming agent, 3 to 7 parts of a flatting agent, 1 to 10 parts of a silane coupling agent, 2 to 3 parts of a wetting agent, 3 to 5 parts of bentonite, 5 to 15 parts of a rheological additive, 195 to 215 parts of pigment and filler, 3 to 7 parts of a flash-rust inhibitor, 3 to 7 parts of a thickening agent, 30 to 35 parts of propylene glycol monomethyl ether, 30 to 35 parts of dipropylene glycol monomethyl ether and 150 to 180 parts of water; the epoxy emulsion is a mixture of an epoxy emulsion EP39 and an epoxy emulsion AQUAER-3011, and the epoxy emulsion is a mixture of an epoxy emulsion EP39 and an epoxy emulsion AQUAER-3011; the water-based epoxy finish paint provided by the invention can be directly applied to the surfaces of polishing-free aluminum parts and electroplated parts, and a coating with high film thickness and high adhesive force is formed, so that a relatively high protection effect is realized.

Description

Technical Field

[0001] This application relates to the technical field of coatings, and particularly to a waterborne epoxy topcoat for aluminum and electroplated parts without grinding and its preparation method. Background Art

[0002] In industrial production, the surface treatment processes of aluminum and electroplated parts can not only provide good protection for workpieces, extend the service life of workpieces, but also enable workpieces to meet diverse requirements. Therefore, they have been widely used in fields such as automotive parts and aerospace components.

[0003] Traditional surface treatment processes mainly include steps such as grinding, pickling, and coating. However, there are some problems with the above surface treatment processes. For example, during the grinding pretreatment, not only a large amount of manpower and material resources are consumed, but also the surface of the workpiece may be damaged, affecting the quality of the final product. In addition, in terms of pursuing high film thickness and high adhesion for the protective coating on the workpiece surface, traditional technologies are difficult to balance both requirements. Especially in application scenarios with high requirements for protective performance, problems such as corrosion and coating peeling are likely to occur during the use of workpieces, seriously affecting the service life and performance of the products. Therefore, it is of great practical significance to develop a waterborne epoxy topcoat that does not require grinding of the substrate workpiece and can achieve high film thickness and high adhesion. Summary of the Invention

[0004] In order to overcome the problems of easy damage to the workpiece surface and difficulty in balancing high film thickness and high adhesion existing in the existing surface treatment processes, this application provides a waterborne epoxy topcoat for aluminum and electroplated parts without grinding and its preparation method.

[0005] In the first aspect, this application provides a waterborne epoxy topcoat for aluminum and electroplated parts without grinding, adopting the following technical scheme: A waterborne epoxy topcoat for aluminum and electroplated parts without grinding, comprising the following components in parts by weight: 480 - 570 parts of epoxy emulsion, 3 - 7 parts of defoamer, 3 - 7 parts of leveling agent, 1 - 10 parts of silane coupling agent, 2 - 3 parts of wetting agent, 3 - 5 parts of bentonite, 5 - 15 parts of rheology aid, 195 - 215 parts of pigment and filler, 3 - 7 parts of anti - flash rust agent, 3 - 7 parts of thickener, 30 - 35 parts of propylene glycol methyl ether, 30 - 35 parts of dipropylene glycol methyl ether, and 150 - 180 parts of water; The epoxy emulsion is a mixture of epoxy emulsion EP39 and epoxy emulsion AQUAER - 3011.

[0006] The present application provides a waterborne epoxy topcoat for aluminum and electroplated parts. This epoxy topcoat uses specially modified epoxy resins (epoxy emulsion EP39 and epoxy emulsion AQUAER-3011), which have good water solubility and affinity for aluminum and electroplated parts, can adhere well to the surfaces of aluminum and electroplated parts, and achieve a good protective effect. In addition, by using a silane coupling agent as an adhesion promoter, it can form chemical bonding with metal atoms on the surfaces of aluminum and electroplated parts and can interact with the resin components in the epoxy topcoat, thereby enabling the topcoat to firmly adhere directly to the surfaces of aluminum and electroplated parts. While improving the impact resistance, abrasion resistance, and corrosion resistance of the workpiece, the grinding step in the traditional process is eliminated, reducing production costs and improving efficiency. The rheology aid and bentonite can improve the anti-sagging performance of the topcoat while increasing the thickness of the coating film, enabling the dry film thickness to reach 100 μm, meeting the application scenarios with high protective performance requirements. In addition, the present application mainly uses water as a diluent, significantly reducing the emissions of volatile organic compounds, meeting environmental protection requirements, and reducing the harm to the environment and human health. In summary, the waterborne epoxy topcoat provided by the present application can be directly used on the surfaces of aluminum and electroplated parts without grinding and form a coating with a high film thickness and high adhesion. The above workpieces will not have problems such as corrosion and coating film peeling during use and have an efficient and lasting protective effect.

[0007] The component A includes the following components in parts by weight: 500 - 550 parts of epoxy emulsion, 3 - 7 parts of defoamer, 3 - 7 parts of leveling agent, 3 - 7 parts of silane coupling agent, 2 - 3 parts of wetting agent, 3 - 5 parts of bentonite, 5 - 15 parts of rheology aid, 195 - 215 parts of pigment and filler, 3 - 7 parts of anti-flash rust agent, 3 - 7 parts of thickener, 30 - 35 parts of propylene glycol methyl ether, 30 - 35 parts of dipropylene glycol methyl ether, and 150 - 180 parts of water.

[0008] In some embodiments, the parts by weight of the epoxy emulsion can be 480 - 500 parts, 480 - 520 parts, 480 - 55 parts, 500 - 520 parts, 500 - 550 parts, 500 - 570 parts, 520 - 550 parts, 520 - 570 parts, or 550 - 570 parts.

[0009] In a specific embodiment, the parts by weight of the epoxy emulsion can also be 480 parts, 500 parts, 520 parts, 550 parts, or 570 parts.

[0010] In some embodiments, the silane coupling agent is 1 - 3 parts, 1 - 5 parts, 1 - 7 parts, 3 - 5 parts, 3 - 7 parts, 3 - 10 parts, 5 - 7 parts, 5 - 10 parts, or 7 - 10 parts.

[0011] In some embodiments, the parts by weight of the silane coupling agent can be 1 part, 3 parts, 5 parts, 7 parts, or 10 parts.

[0012] The weight ratio of the epoxy emulsion EP39 to the epoxy emulsion AQUAER-3011 is 1:(0.65 - 0.80).

[0013] In some embodiments, the weight ratio of the epoxy emulsion EP39 to the epoxy emulsion AQUAER-3011 is 1:(0.55 - 0.65), 1:(0.55 - 0.73), 1:(0.55 - 0.80), 1:(0.65 - 0.73), 1:(0.65 - 0.80), 1:(0.65 - 0.90), 1:(0.73 - 0.80), 1:(0.73 - 0.90) or 1:(0.80 - 0.90).

[0014] In a specific embodiment, the weight ratio of the epoxy emulsion EP39 to the epoxy emulsion AQUAER-3011 can also be 1:0.55, 1:0.65, 1:0.73, 1:0.80 or 1:0.90.

[0015] Optionally, the silane coupling agent is silane Momentive COATOSIL MP200.

[0016] Optionally, the B component is the epoxy curing agent Aifulong 3986; the weight ratio of the A component to the B component is 100:(13 - 15).

[0017] In a second aspect, the present application provides a method for preparing a waterborne epoxy topcoat without sanding, including the following steps for preparing the A component: (1) First, pre-disperse bentonite to obtain a pre-dispersed bentonite slurry; (2) Premix the flash rust inhibitor with part of the water to obtain a pre-mixed flash rust inhibitor; premix the thickener with part of the propylene glycol methyl ether to obtain a pre-mixed thickener; premix part of the propylene glycol methyl ether, dipropylene glycol methyl ether and water to obtain a pre-mixed solvent; (3) Add the epoxy emulsion to the reaction kettle, start the stirrer at a speed of 300 - 500 rpm; then slowly add the defoamer, leveling agent, silane coupling agent and wetting agent in sequence, and stir for 15 - 20 min; (4) Then add the pre-mixed solvent, pre-dispersed bentonite slurry, pigment, filler and rheological aid, and stir at a speed of 500 - 800 rpm for 20 - 30 min; (5) Finally, add the pre-mixed flash rust inhibitor and pre-mixed thickener in sequence, and stir at a speed of 500 - 800 rpm for 20 - 30 min to obtain the A component.

[0018] Optionally, the speed of the pre-dispersion is 1000 - 1500 rpm, the speed gradually increases during the pre-dispersion process, and the stirring time of the pre-dispersion is 20 - 30 min.

[0019] Optionally, the rotation speed of the premixing is 250 - 350 rpm, and the time is 8 - 10 min.

[0020] In a third aspect, the present application provides the application of the non - grinding water - borne epoxy topcoat on the surfaces of aluminum parts and electroplated parts.

[0021] Optionally, the spraying method of the non - grinding water - borne epoxy topcoat on the surfaces of aluminum parts and electroplated parts is as follows: Mix material A and material B and add water, stir evenly to obtain a mixed coating; then directly spray the mixed coating on the surfaces of non - grinding aluminum parts and electroplated parts, and after curing, it is obtained; Wherein, the addition amount of the water is 10 - 30% of the total weight of material A and material B; The curing conditions are curing at 20℃ - 30℃ for 12 - 16 h; or the curing conditions are baking at 60℃ - 70℃ for 2 - 3 h.

[0022] In summary, the present application has the following beneficial effects: 1. The present application uses epoxy emulsion EP39, epoxy emulsion AQUAER - 3011, silane coupling agent, etc. to prepare a water - borne epoxy topcoat. This water - borne epoxy topcoat can be directly used on the surfaces of non - grinding aluminum parts and electroplated parts, and form a coating with high film thickness and high adhesion. The above - mentioned workpieces will not have problems such as corrosion and film peeling during use, and have an efficient and lasting protection effect.

[0023] 2. By further controlling the addition amount of the epoxy emulsion within 500 - 550 parts and the addition amount of the silane coupling agent within 3 - 7 parts, the non - grinding water - borne epoxy topcoat obtained in the present application has a better protection effect on aluminum parts and electroplated parts. Its salt - spray resistance time for the aluminum parts after surface coating is ≥1000 h, and the salt - spray resistance time for the electroplated parts after surface coating is ≥900 h.

[0024] 3. By further controlling the weight ratio of epoxy emulsion EP39 to epoxy emulsion AQUAER - 3011 within the range of 1:(0.65 - 0.8), the non - grinding water - borne epoxy topcoat obtained has a better protection effect on aluminum parts and electroplated parts. Its salt - spray resistance time for the aluminum parts after surface coating is ≥1100 h, and the salt - spray resistance time for the electroplated parts after surface coating is ≥1000 h. Specific embodiments

[0025] The present application provides a waterborne epoxy topcoat for aluminum parts and electroplated parts, which is characterized by comprising Component A and Component B; Component A comprises the following components in parts by weight: 480 - 570 parts of epoxy emulsion, 3 - 7 parts of defoamer, 3 - 7 parts of leveling agent, 1 - 10 parts of silane coupling agent, 2 - 3 parts of wetting agent, 3 - 5 parts of bentonite, 5 - 15 parts of rheological aid, 195 - 215 parts of pigment and filler, 3 - 7 parts of anti - flash rust agent, 3 - 7 parts of thickener, 30 - 35 parts of propylene glycol methyl ether, 30 - 35 parts of dipropylene glycol methyl ether and 150 - 180 parts of water; Component B is epoxy curing agent Ailu 3986; Further, Component A comprises the following components in parts by weight: 500 - 550 parts of epoxy emulsion, 3 - 7 parts of defoamer, 3 - 7 parts of leveling agent, 3 - 7 parts of silane coupling agent, 2 - 3 parts of wetting agent, 3 - 5 parts of bentonite, 5 - 15 parts of rheological aid, 195 - 215 parts of pigment and filler, 3 - 7 parts of anti - flash rust agent, 3 - 7 parts of thickener, 30 - 35 parts of propylene glycol methyl ether, 30 - 35 parts of dipropylene glycol methyl ether and 150 - 180 parts of water; Among them, the epoxy emulsion is a mixture of epoxy emulsion EP39 and epoxy emulsion AQUAER - 3011; Further, the weight ratio of epoxy emulsion EP39 to epoxy emulsion AQUAER - 3011 is 1:(0.65 - 0.80).

[0026] The present application provides a preparation method of the waterborne epoxy topcoat without grinding, including the following steps for preparing Component A: (1) First, slowly add bentonite into water, stir at a speed of 1000 - 1500 rpm, and gradually increase the speed. The stirring time for pre - dispersion is 20 - 30 min to obtain a pre - dispersed bentonite slurry; (2) Premix the anti - flash rust agent with part of water to obtain an anti - flash rust agent premix; Premix the thickener with part of propylene glycol methyl ether to obtain a thickener premix; Premix part of propylene glycol methyl ether, dipropylene glycol methyl ether and water to obtain a premixed solvent; The speed of premixing is 250 - 350 rpm and the time is 8 - 10 min; (3) Add the epoxy emulsion into the reaction kettle, start the stirrer, and the speed is 300 - 500 rpm; Then slowly add the defoamer, leveling agent, silane coupling agent and wetting agent in sequence, and stir for 15 - 20 min; (4) Then add the premixed solvent, pre - dispersed bentonite slurry, pigment and filler, and rheological aid, and stir at a speed of 500 - 800 rpm for 20 - 30 min; (5) Finally, add the anti - flash rust agent premix and thickener premix in sequence, and stir at a speed of 500 - 800 rpm for 20 - 30 min to obtain Component A.

[0027] In the embodiments of the present application, the defoaming agent is BASF 104E; the leveling agent is BYK346; the silane coupling agent is Momentive COATOSIL MP200; the wetting agent is Tego 4100; the bentonite is Elementis BENTONEEW; the rheology additive is BYK AQUATIX 8421; the fillers and pigments are barium sulfate, titanium dioxide R996 and carbon black MA100; the anti-corrosion agent for preventing flash rust is BYK RAYB060; the thickening agent is Münzing BorchiGel 0620; the raw materials, reagents, solvents, etc. used in the present application can all be obtained through commercial purchase.

[0028] The present application will be further described in detail below in conjunction with examples and performance detection tests.

[0029] Example 1 Example 1 provides a waterborne epoxy topcoat without sanding.

[0030] The difference in the above embodiments lies in the addition amounts of the epoxy emulsion and the silane coupling agent, as specifically shown in Table 1 below.

[0031] The preparation method of the waterborne epoxy topcoat without sanding provided in Examples 1-9 includes the following steps: Preparation of Material A: (1) First, slowly add 4 g of bentonite to 136 g of water, stir at a speed of 1000 rpm, gradually increase the speed, and the pre-dispersion stirring time is 20 min to obtain a pre-dispersed bentonite slurry; (2) Premix 5 g of the anti-corrosion agent for preventing flash rust with 10 g of water to obtain a pre-mixed anti-corrosion agent; premix 5 g of the thickening agent with 5 g of propylene glycol methyl ether to obtain a pre-mixed thickening agent; premix 30 g of propylene glycol methyl ether, 35 g of dipropylene glycol methyl ether and 20 g of water to obtain a pre-mixed solvent; the premixing speed is 300 rpm and the time is 10 min; (3) Add the epoxy emulsion (epoxy emulsion EP39 and epoxy emulsion AQUAER-3011 with a weight ratio of 1:0.55) to the reaction kettle, turn on the stirrer, and the speed is 400 rpm; then slowly add 5 g of the defoaming agent, 5 g of the leveling agent, the silane coupling agent and 2.5 g of the wetting agent in sequence, and stir for 20 min; (4) Then add the pre-mixed solvent, the pre-dispersed bentonite slurry, 50 g of barium sulfate, 150 g of titanium white paste, 2 g of carbon black and 10 g of the rheology additive, and stir at a speed of 600 rpm for 20 - 30 min; (5) Finally, add the pre-mixed anti-corrosion agent and the pre-mixed thickening agent, and stir at a speed of 600 rpm for 20 min to obtain Material A.

[0032] Material B: Epoxy curing agent Araldite 3986.

[0033] Table 1 Dosages of epoxy emulsion and silane coupling agent in the polishing-free waterborne epoxy topcoat provided in Examples 1-9 Examples 10-13 Examples 10-13 provide a polishing-free waterborne epoxy topcoat.

[0034] The difference between the above examples and Example 3 lies in: the type and ratio of epoxy emulsion, as shown in Table 2 below.

[0035] Table 2 Type and ratio of epoxy emulsion in the polishing-free waterborne epoxy topcoat of Examples 10-13 Comparative Example 1 Comparative Example 1 provides a polishing-free waterborne epoxy topcoat.

[0036] The difference between the above examples and Example 3 lies in: the epoxy emulsion is only epoxy emulsion EP39.

[0037] Comparative Example 2 Comparative Example 2 provides a polishing-free waterborne epoxy topcoat.

[0038] The difference between the above examples and Example 3 lies in: the epoxy emulsion is only epoxy emulsion AQUAER-3011.

[0039] Comparative Example 3 Comparative Example 3 provides a polishing-free waterborne epoxy topcoat.

[0040] The difference between the above examples and Example 3 lies in: epoxy emulsion EP39 is replaced with epoxy emulsion EP146.

[0041] Comparative Example 4 Comparative Example 4 provides a polishing-free waterborne epoxy topcoat.

[0042] The difference between the above examples and Example 3 lies in: epoxy emulsion AQUAER-3011 is replaced with epoxy emulsion EP146.

[0043] Comparative Example 5 Comparative Example 5 provides a polishing-free waterborne epoxy topcoat.

[0044] The difference between the above examples and Example 3 lies in: the dosage of silane coupling agent is 0.

[0045] Performance detection test The polishing-free waterborne epoxy topcoats obtained in Examples 1-13 and Comparative Examples 1-5 are respectively applied to the surfaces of aluminum parts and electro-galvanized parts. The specific application method is as follows: Mix 100 g of Material A with 14 g of Material B, then add 20 g of water and stir evenly to obtain a mixed coating; then directly spray the mixed coating on the surface of the substrate that does not need to be polished and cure it at 25°C for 14 h to form a dry film with a dry film thickness of 100 μm on the surface of the substrate.

[0046] Perform film adhesion and salt spray resistance performance tests on the sprayed aluminum parts and electro-galvanized parts respectively, and the results are shown in Table 3 below.

[0047] Table 3 Test results of film adhesion and salt spray resistance performance of each aluminum part and electro-galvanized part According to the test results in Table 3, it can be seen that after the surface of the aluminum parts and electro-galvanized parts are coated with the non-grinding waterborne epoxy topcoat obtained in Examples 1-13 of the present application, the adhesion grade of the film on the surface of the aluminum parts is 0, and the salt spray resistance time of the aluminum parts is 888-1176 h; the adhesion grade of the film on the surface of the aluminum parts is 0-1, and the salt spray resistance time of the aluminum parts is 840-1104 h; while after the surface of the aluminum parts and electro-galvanized parts are coated with the non-grinding waterborne epoxy topcoat obtained in Comparative Examples 1-5, the adhesion grade of the film on the surface of the aluminum parts is 0-1, and the salt spray resistance time of the aluminum parts is 744-864 h; the adhesion grade of the film on the surface of the aluminum parts is 0-2, and the salt spray resistance time of the aluminum parts is 696-792 h. Therefore, it shows that the waterborne epoxy topcoat obtained by using the mixture of epoxy emulsion EP39 and epoxy emulsion AQUAER-3011 as the epoxy emulsion and using the silane coupling agent as the adhesion promoter in the present application can be directly applied to the surface of unpolished aluminum parts and electro-galvanized parts, and the surface film adhesion of the obtained aluminum parts and electro-galvanized parts is good, the dry film thickness is high, and the protection effect on the aluminum parts and electro-galvanized parts is excellent.

[0048] From the test results of Examples 1-9, it can be seen that after the surface of the aluminum parts and electro-galvanized parts are coated with the non-grinding waterborne epoxy topcoat obtained in Examples 1, 5-6, and 9, the adhesion grade of the film on the surface of the aluminum parts is 0-1, and the salt spray resistance time of the aluminum parts is 888-984 h; the adhesion grade of the film on the surface of the aluminum parts is 0-1, and the salt spray resistance time of the aluminum parts is 840-912 h; while after the surface of the aluminum parts and electro-galvanized parts are coated with the non-grinding waterborne epoxy topcoat obtained in Examples 2-4 and 7-8, the adhesion grade of the film on the surface of the aluminum parts is 0, and the salt spray resistance time of the aluminum parts is 1008-1080 h (≥1000 h); the adhesion grade of the film on the surface of the aluminum parts is 0, and the salt spray resistance time of the aluminum parts is 936-1008 h (≥900 h), indicating that the present application further controls the addition amount of the epoxy emulsion within the range of 500-550 parts and the addition amount of the silane coupling agent within the range of 3-7 parts, and the obtained non-grinding waterborne epoxy topcoat has a better protection effect on the aluminum parts and electro-galvanized parts.

[0049] From the test results of Example 3 and Examples 10-13, it can be seen that after the surface of aluminum parts and electroplated parts is coated with the waterborne epoxy topcoat without grinding obtained in Example 3 and Example 13, the adhesion grade of the coating film on the surface of the aluminum parts is 0, and the salt spray resistance time of the aluminum parts is 1056-1080 h; the adhesion grade of the coating film on the surface of the aluminum parts is 0, and the salt spray resistance time of the aluminum parts is 984-1008 h; while after the surface of aluminum parts and electroplated parts is coated with the waterborne epoxy topcoat without grinding obtained in Examples 10-12, the adhesion grade of the coating film on the surface of the aluminum parts is 0, and the salt spray resistance time of the aluminum parts is 1152-11760 h (≥1100 h); the adhesion grade of the coating film on the surface of the aluminum parts is 0, and the salt spray resistance time of the aluminum parts is 1056-1104 h (≥1000 h), indicating that the present application further controls the weight ratio of epoxy emulsion EP39 to epoxy emulsion AQUAER-3011 within the range of 1:(0.65-0.8), and the obtained waterborne epoxy topcoat without grinding has a better protection effect on aluminum parts and electroplated parts.

[0050] Although the present invention has been described in detail with general descriptions and specific embodiments above, on the basis of the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of the present invention claimed.

Claims

1. A non-grinding water-based epoxy topcoat for aluminum parts and electroplated parts, characterized in that: The invention comprises material A and material B; the material A comprises the following components in parts by weight: 480-570 parts of epoxy emulsion, 3-7 parts of defoamer, 3-7 parts of leveling agent, 1-10 parts of silane coupling agent, 2-3 parts of wetting agent, 3-5 parts of bentonite, 5-15 parts of rheological additive, 195-215 parts of pigment and filler, 3-7 parts of flash rust preventer, 3-7 parts of thickener, 30-35 parts of propylene glycol methyl ether, 30-35 parts of dipropylene glycol methyl ether and 150-180 parts of water; The epoxy emulsion is a mixture of epoxy emulsion EP39 and epoxy emulsion AQUAER-3011.

2. The grinding-free water-based epoxy topcoat according to claim 1, characterized in that: The material A comprises the following components in parts by weight: 500-550 parts of epoxy emulsion, 3-7 parts of defoaming agent, 3-7 parts of leveling agent, 3-7 parts of silane coupling agent, 2-3 parts of wetting agent, 3-5 parts of bentonite, 5-15 parts of rheological additive, 195-215 parts of pigment and filler, 3-7 parts of anti-flash rust agent, 3-7 parts of thickener, 30-35 parts of propylene glycol methyl ether, 30-35 parts of dipropylene glycol methyl ether and 150-180 parts of water.

3. The grinding-free water-based epoxy topcoat according to claim 1, characterized in that: The weight ratio of the epoxy emulsion EP39 to the epoxy emulsion AQUAER-3011 is 1:(0.65-0.80).

4. The grinding-free water-based epoxy topcoat according to claim 1, characterized in that: The silane coupling agent is silane Momentive COATOSILMP200.

5. The grinding-free water-based epoxy topcoat according to any one of claims 1 to 4, characterized in that: The material B is epoxy curing agent ALOY 3986; The weight ratio of material A to material B is 100:(13-15).

6. The method for preparing the grinding-free water-based epoxy topcoat according to any one of claims 1 to 5, characterized in that: The method comprises the following steps of preparing material A: (1) firstly pre-dispersing bentonite to obtain pre-dispersed bentonite slurry; (2) premixing the flash rust inhibitor with part of water to obtain a flash rust inhibitor premix; premixing the thickener with part of propylene glycol methyl ether to obtain a thickener premix; premixing part of propylene glycol methyl ether and dipropylene glycol methyl ether with water to obtain a premixed solvent; (3) Add the epoxy emulsion into the reactor and start the agitator at a speed of 300-500 rpm; then slowly add the defoamer, leveling agent, silane coupling agent and wetting agent in sequence and stir for 15-20 minutes; (4) Then add the premixed solvent, pre-dispersed bentonite slurry, pigments, fillers and rheological additives, and stir at a speed of 500-800 rpm for 20-30 minutes; (5) Finally, add the anti-flash rust agent premix and the thickener premix in sequence, and stir at a speed of 500-800 rpm for 20-30 minutes to obtain material A.

7. The method for preparing the grinding-free waterborne epoxy topcoat according to claim 6, characterized in that: The rotation speed of the pre-dispersion is 1000-1500 rpm, the rotation speed gradually increases during the pre-dispersion process, and the stirring time of the pre-dispersion is 20-30 minutes.

8. The method for preparing the grinding-free waterborne epoxy topcoat according to claim 6, characterized in that: The rotation speed of the premix is ​​250-350 rpm, and the time is 8-10 min.

9. Use of the grinding-free water-based epoxy topcoat as described in any one of claims 1 to 4 on the surface of aluminum parts and electroplated parts.

10. The use according to claim 9, characterized in that: The spraying method of the non-grinding water-based epoxy topcoat on the surface of aluminum parts and electroplated parts is: Mix material A and material B, add water, stir evenly, and obtain a mixed coating; then spray the mixed coating directly on the surface of aluminum parts and electroplated parts that do not need to be polished, and cure to obtain the mixed coating; Wherein, the amount of water added is 10-30% of the total weight of material A and material B; The curing condition is curing at 20° C.-30° C. for 12-16 hours; or the curing condition is baking at 60° C.-70° C. for 2-3 hours.

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