Waterborne epoxy primer-topcoat coating as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of coatings, and particularly relates to a waterborne epoxy primer-topcoat coating as well as a preparation method and application thereof. The coating comprises a component A and a component B, the component A comprises a water-based epoxy emulsion, a coalescing agent and a salt spray resistant agent; the component B comprises an amine curing agent and an auxiliary agent; the amine curing agent is obtained by using polyamine, bisphenol A epoxy resin and polyethylene glycol diglycidyl ether as main chain segments and carrying out end-capping by using an end-capping reagent; the epoxy value of the bisphenol A epoxy resin is greater than or equal to 0.48 eq / 100g. According to the invention, polyamine, bisphenol A epoxy resin and polyethylene glycol diglycidyl ether are used as main chain segments, and an end-capping reagent is used for end capping to prepare the amine curing agent. The introduction of a specific type of epoxy resin not only can improve the compatibility of the amine curing agent and the waterborne epoxy emulsion and improve the gloss, but also can increase the permeability of a film forming matter and enhance the adhesive force with multiple substrates, and meanwhile, by combining with other components, the coating has good protection performance.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and particularly relates to a waterborne epoxy primer-surface integrated coating and a preparation method and application thereof. Background Art

[0002] As one of the most commonly used means of transportation, cars operate in a complex and changeable environment and are usually subject to severe corrosion. As the power source of the car, protecting the engine to reduce or even avoid corrosion is crucial to the safe operation of the car.

[0003] Engine protection involves a wide variety of substrates, including cast iron, aluminum alloy, nylon composite glass fiber materials, various smooth machined surfaces, plastics, electrophoretic substrates, powder substrates, etc. This feature is a huge challenge for engine protective coatings, because in order to effectively protect the above-mentioned wide variety of substrates, the protective coatings need to have good adhesion to these substrates. For a long time, oil-based coatings have dominated the market with their performance and price advantages, but oil-based coatings emit a large amount of volatile gases (VOCs) during use, causing serious damage to the environment. Therefore, engine coatings have gradually shifted from oil-based coatings to water-based coatings, but current water-based coatings still have problems with multi-substrate adhesion and poor corrosion resistance, and cannot meet the engine protection needs well.

[0004] Therefore, it is of great significance to provide a coating that has good adhesion to multiple substrates and good anti-corrosion performance. Summary of the invention

[0005] The present invention aims to solve one or more technical problems existing in the above-mentioned prior art and at least provide a beneficial choice. Specifically, the present invention provides a water-based epoxy primer-top coating, which has good adhesion to multiple substrates and good anti-corrosion performance, and can achieve good protective effect.

[0006] The inventive concept of the present invention is as follows: the coating of the present invention comprises component A and component B; the component A comprises waterborne epoxy emulsion, film-forming aid, and salt spray resistant aid; the component B comprises an amine curing agent and an aid; the amine curing agent is obtained by using polyamine, bisphenol A epoxy resin, and polyethylene glycol diglycidyl ether as main chain segments and end-capping with an end-capping agent; the epoxy value of the bisphenol A epoxy resin is greater than or equal to 0.48eq / 100g. The present invention utilizes the reaction of epoxy groups and primary amine hydrogen, uses polyamine, bisphenol A epoxy resin, and polyethylene glycol diglycidyl ether as main chain segments, and end-capsulates with an end-capping agent to obtain an amine curing agent. The introduction of a specific type of epoxy resin can not only improve the compatibility of the amine curing agent and the waterborne epoxy emulsion, improve the gloss, but also increase the permeability of the film-forming material, enhance the adhesion to multiple substrates, and at the same time combine with other components so that the coating has good anti-corrosion performance and can achieve good protection of the engine.

[0007] Therefore, a first aspect of the present invention provides a waterborne epoxy primer-top coating.

[0008] Specifically, the waterborne epoxy primer-surface all-in-one coating comprises component A and component B;

[0009] The component A comprises a water-based epoxy emulsion, a film-forming aid, and a salt spray resistance aid;

[0010] The B component includes an amine curing agent and an auxiliary agent;

[0011] The amine curing agent is obtained by using polyamine, bisphenol A epoxy resin, and polyethylene glycol diglycidyl ether as main chain segments and end-capping with an end-capping agent;

[0012] The epoxy value of the bisphenol A epoxy resin is greater than or equal to 0.48 eq / 100 g.

[0013] Preferably, the ratio of the epoxy equivalent in the A component to the active hydrogen equivalent in the B component is (1.1-1.5):1.

[0014] Further preferably, the ratio of the epoxy equivalent in the A component to the active hydrogen equivalent in the B component is (1.2-1.4):1.

[0015] Preferably, the epoxy value of the bisphenol A epoxy resin is 0.48-0.58 eq / 100 g; more preferably, the epoxy value of the bisphenol A epoxy resin is 0.48-0.54 eq / 100 g.

[0016] Preferably, the bisphenol A type epoxy resin is epoxy resin E-51.

[0017] Preferably, the aqueous epoxy emulsion includes at least one of solid epoxy emulsion, liquid epoxy emulsion, and acrylic modified epoxy emulsion; when the aqueous epoxy emulsion includes solid epoxy emulsion and acrylic modified epoxy emulsion, the amount of the solid epoxy emulsion is greater than the amount of the acrylic modified epoxy emulsion.

[0018] Preferably, the film-forming aid includes an ether ester solvent; more preferably, the film-forming aid includes dipropylene glycol butyl ether (DPNB).

[0019] Preferably, the salt spray resistance additive comprises a compound of phosphate and organic matter.

[0020] Preferably, the polyamine comprises triethylenetetramine (TETA).

[0021] Preferably, the capping agent comprises n-butyl glycidyl ether (BGE).

[0022] Preferably, the component A further comprises at least one of a thickener and water.

[0023] Preferably, the thickener comprises a polyurethane thickener.

[0024] Preferably, the component B further comprises water; and the auxiliary agent comprises at least one of a defoaming agent, a wetting agent, a leveling agent, an anti-flash rust auxiliary agent, and a cosolvent.

[0025] Further preferably, the additives include a defoamer, a wetting agent, a leveling agent, an anti-flash rust additive, and a solvent.

[0026] Preferably, the defoaming agent comprises a silicone defoaming agent.

[0027] Preferably, the wetting agent includes a silicone wetting agent; further preferably, the wetting agent is tego4100, which is a polyether-modified silicone with a twin star structure, which can significantly reduce the surface tension of the coating, prevent cavitation, help improve the adhesion of the coating, and also improve the surface smoothness and glossiness of the coating.

[0028] Preferably, the leveling agent comprises an organic silicon leveling agent.

[0029] Preferably, the anti-flash rust additive includes at least one of nitrite, molybdate, multi-organometallic chelate, and multi-functional phosphate polymer.

[0030] Preferably, the co-solvent comprises butyl glycol (BCS).

[0031] Preferably, the coating comprises component A and component B; component A comprises water-based epoxy emulsion, film-forming aid, salt spray resistant aid, thickener, and water; component B comprises amine curing agent, defoaming agent, wetting agent, leveling agent, anti-flash rust aid, cosolvent, and water; and in parts by mass, component A comprises 65-85 parts of water-based epoxy emulsion, 3.5-5.5 parts of film-forming aid, 0.9-2.2 parts of salt spray resistant aid, 0.9-2.2 parts of thickener, and 14-28 parts of water; component B comprises 35-55 parts of amine curing agent, 0.5-1.1 parts of defoaming agent, 0.5-1.1 parts of wetting agent, 0.5-1.1 parts of leveling agent, 2.5-4.5 parts of anti-flash rust aid, 9-16 parts of cosolvent, and 25-45 parts of water.

[0032] Further preferably, the coating comprises component A and component B; component A comprises water-based epoxy emulsion, film-forming aid, salt spray resistant aid, thickener, and water; component B comprises amine curing agent, defoaming agent, wetting agent, leveling agent, anti-flash rust aid, solvent, and water; and in parts by mass, component A comprises 70-80 parts of water-based epoxy emulsion, 4-5 parts of film-forming aid, 1-2 parts of salt spray resistant aid, 1-2 parts of thickener, and 15-25 parts of water; component B comprises 40-50 parts of amine curing agent, 0.5-1 part of defoaming agent, 0.5-1 part of wetting agent, 0.5-1 part of leveling agent, 3-4 parts of anti-flash rust aid, 10-15 parts of solvent, and 30-40 parts of water.

[0033] Preferably, the mass ratio of component A to component B is 2.5-5.5:1; further preferably, the mass ratio of component A to component B is 3-5:1.

[0034] The second aspect of the present invention provides a method for preparing the waterborne epoxy primer-top coating according to the first aspect of the present invention.

[0035] Specifically, the preparation method of the waterborne epoxy primer-surface integrated coating comprises the following steps:

[0036] (1) mixing the raw material components of the A component to obtain the A component;

[0037] (2) mixing the raw material components of the B component to obtain the B component;

[0038] The A component and the B component are mixed to prepare the coating.

[0039] Preferably, step (1) is specifically to mix the aqueous epoxy emulsion, the film-forming aid, the salt spray resistance aid and water, perform a first dispersion, then add the thickener, perform a second dispersion, adjust the viscosity, and obtain component A.

[0040] Preferably, the rotation speed of the first dispersion is 700-1100 rpm, and the time of the first dispersion is 9-17 min; further preferably, the rotation speed of the first dispersion is 750-1000 rpm, and the time of the first dispersion is 10-15 min.

[0041] Preferably, the rotation speed of the second dispersion is 450-800 rpm, and the time of the second dispersion is 9-17 min; further preferably, the rotation speed of the second dispersion is 500-750 rpm, and the time of the second dispersion is 10-15 min.

[0042] Preferably, the viscosity is adjusted to 60-90 ku; further preferably, the viscosity is adjusted to 70-80 ku.

[0043] Preferably, in step (2), mixing is performed by stirring and dispersing.

[0044] Preferably, the stirring and dispersing rotation speed is 700-1100 rpm, and the stirring and dispersing time is 9-17 min; further preferably, the stirring and dispersing rotation speed is 750-1000 rpm, and the stirring and dispersing time is 10-15 min.

[0045] Preferably, the method for preparing the amine curing agent comprises the following steps:

[0046] The polyamine, bisphenol A epoxy resin and polyethylene glycol diglycidyl ether are mixed and reacted for the first time, and then a capping agent is added and reacted for the second time to obtain the amine curing agent.

[0047] Preferably, the temperature of the first reaction is 55-75°C, and the time of the first reaction is 3-5h; further preferably, the temperature of the first reaction is 60-70°C, and the time of the first reaction is 3.5-4.5h; further preferably, the temperature of the first reaction is 65°C, and the time of the first reaction is 4h.

[0048] Preferably, the temperature of the second reaction is 55-75°C, and the time of the second reaction is 1.5-3.5h; further preferably, the temperature of the second reaction is 60-70°C, and the time of the second reaction is 2-3h; further preferably, the temperature of the second reaction is 65°C, and the time of the second reaction is 2.5h.

[0049] Specifically, the amine curing agent of the present invention is very important for improving the adhesion between the coating and multiple substrates. The present invention utilizes the reaction between epoxy groups and primary amine hydrogen, uses polyamines and bisphenol A epoxy resins, polyethylene glycol diglycidyl ether (PEGDGE) as the main chain segments, and uses a capping agent for end-capping to prepare an amine curing agent. The introduction of a specific bisphenol A epoxy resin into the curing agent can not only improve the compatibility of the amine curing agent and the epoxy emulsion, but also improve the gloss; it can also increase the permeability of the film-forming material and enhance the adhesion to the substrate.

[0050] A third aspect of the present invention provides an engine.

[0051] Specifically, the engine includes a coating formed by the waterborne epoxy primer and surface-in-one coating described in the first aspect of the present invention.

[0052] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0053] (1) The present invention utilizes the reaction of epoxy groups with primary amine hydrogen, uses polyamine, bisphenol A epoxy resin, and polyethylene glycol diglycidyl ether as the main chain segments, and uses a capping agent to cap the end to obtain an amine curing agent. The introduction of a specific type of epoxy resin can not only improve the compatibility of the amine curing agent and the water-based epoxy emulsion, improve the gloss, but also increase the permeability of the film-forming material and enhance the adhesion to multiple substrates. At the same time, combined with other components, the coating can also have good anti-corrosion properties and can achieve good protection for the engine.

[0054] (2) When the water-based epoxy emulsion of the present invention includes a solid epoxy emulsion and an acrylic acid-modified epoxy emulsion, the amount of the solid epoxy emulsion used is greater than the amount of the acrylic acid-modified epoxy emulsion used, which can improve the appearance gloss, hardness, and moisture and heat resistance of the coating. In addition, the present invention uses a specific salt spray resistant additive to improve the salt spray resistance of the coating.

[0055] (3) The preparation process of the present invention is simple and convenient for large-scale production and application. DETAILED DESCRIPTION

[0056] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0057] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0058] The raw material information of Examples 1-4 of the present invention and Comparative Examples 1-4 is shown in Table 1.

[0059] Table 1: Raw material information of Examples 1-4 and Comparative Examples 1-4 of the present invention

[0060]

[0061] In Table 1, “-” means “not tested”.

[0062] Example 1

[0063] A waterborne epoxy primer-top coating, the composition and dosage of which are shown in Table 2.

[0064] Table 2: Composition and dosage of waterborne epoxy primer and surface coating in Example 1

[0065]

[0066]

[0067] A method for preparing a waterborne epoxy primer-top coating comprises the following steps:

[0068] (1) Mixing an aqueous epoxy emulsion, a film-forming aid, a salt spray resistant aid, and deionized water, dispersing the mixture at a speed of 750 rpm for 12 min, adding a thickener, dispersing the mixture at a speed of 500 rpm for 12 min, adjusting the viscosity to 75 ku, and mixing the mixture uniformly to obtain component A;

[0069] (2) The raw material components of component B are mixed evenly, and dispersed for 12 minutes at a rotation speed of 750 rpm to obtain component B; the components A and B obtained in step (1) are mixed evenly to obtain a water-based epoxy primer-surface coating.

[0070] Wherein, the preparation method of the amine curing agent in component B comprises the following steps:

[0071] Add TETA to a four-necked flask, raise the temperature to 65°C, then drop a mixture of E-51 and PEGDGE while stirring, wherein the molar ratio of TETA to epoxy resin E-51 is 2.2:1, and add the mixture within 2 hours. Continue to react for 2 hours to obtain an epoxy polyamine adduct, and distill off the excess polyamine under reduced pressure; drop the capping agent BGE into the adduct, and after the addition is completed, react at 65°C for 2 hours; add distilled water to the product, stir for 1 hour and then stop stirring to obtain an amine curing agent.

[0072] Example 2

[0073] A waterborne epoxy primer-top coating, the composition and dosage of which are shown in Table 3.

[0074] Table 3: Composition and dosage of waterborne epoxy primer and surface coating in Example 2

[0075]

[0076]

[0077] A method for preparing a waterborne epoxy primer-top coating comprises the following steps:

[0078] (1) Mixing an aqueous epoxy emulsion, a film-forming aid, a salt spray resistant aid, and deionized water, dispersing the mixture at a speed of 900 rpm for 10 min, adding a thickener, dispersing the mixture at a speed of 600 rpm for 10 min, adjusting the viscosity to 75 ku, and mixing the mixture uniformly to obtain component A;

[0079] (2) The raw material components of component B are mixed evenly, and dispersed at a rotation speed of 900 rpm for 10 minutes to obtain component B; the components A and B obtained in step (1) are mixed evenly to obtain a water-based epoxy primer-surface coating.

[0080] Among them, the preparation method of the amine curing agent in component B is the same as that in Example 1.

[0081] Example 3

[0082] A waterborne epoxy primer-top coating, the composition and dosage of which are shown in Table 4.

[0083] Table 4: Composition and dosage of waterborne epoxy primer and surface coating in Example 3

[0084]

[0085]

[0086] A method for preparing a waterborne epoxy primer-top coating comprises the following steps:

[0087] (1) Mixing an aqueous epoxy emulsion, a film-forming aid, a salt spray resistant aid, and deionized water, dispersing for 10 minutes at a speed of 1000 rpm, adding a thickener, dispersing for 10 minutes at a speed of 750 rpm, adjusting the viscosity to 80 ku, and mixing uniformly to obtain component A;

[0088] (2) The raw material components of component B are mixed evenly, and dispersed at a rotation speed of 1000 rpm for 10 minutes to obtain component B; the components A and B obtained in step (1) are mixed evenly to obtain a water-based epoxy primer-surface coating.

[0089] Among them, the preparation method of the amine curing agent in component B is the same as that in Example 1.

[0090] Example 4

[0091] A water-based epoxy primer-top coating, the composition and dosage of which are shown in Table 5.

[0092] Table 5: Composition and dosage of waterborne epoxy primer and surface coating in Example 4

[0093]

[0094]

[0095] A method for preparing a waterborne epoxy primer-top coating comprises the following steps:

[0096] (1) Mixing an aqueous epoxy emulsion, a film-forming aid, a salt spray resistant aid, and deionized water, dispersing the mixture at a speed of 800 rpm for 15 min, adding a thickener, dispersing the mixture at a speed of 600 rpm for 15 min, adjusting the viscosity to 80 ku, and mixing the mixture uniformly to obtain component A;

[0097] (2) The raw material components of component B are mixed evenly, and dispersed at a rotation speed of 800 rpm for 15 minutes to obtain component B; the components A and B obtained in step (1) are mixed evenly to obtain a water-based epoxy primer-surface coating.

[0098] Among them, the preparation method of the amine curing agent in component B is the same as that in Example 1.

[0099] Comparative Example 1

[0100] The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 uses 33 parts by mass of curing agent 38-1 (the curing agent is different, the active hydrogen equivalent is different, and this addition amount can make the ratio of epoxy equivalent to active hydrogen equivalent in Comparative Example 1 consistent with that in Example 1) to replace the amine curing agent in Example 1, and the amount of deionized water used is 48.7 parts, and the rest is the same as Example 1.

[0101] Comparative Example 2

[0102] The only difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, the amounts of epoxy emulsion 2060 and epoxy emulsion AEH20 are 30 parts and 50 parts respectively, and the amount of deionized water is 13 parts, and the rest is the same as Example 1.

[0103] Comparative Example 3

[0104] The only difference between Comparative Example 3 and Example 1 is that in the preparation process of the amine curing agent in Comparative Example 3, an equal amount of epoxy resin E44 (epoxy value of 0.41-0.47 eq / 100 g) is used to replace E-51 in Example 1, and the rest is the same as Example 1.

[0105] Comparative Example 4

[0106] The difference between Comparative Example 4 and Example 1 is that Comparative Example 4 uses an equal amount of phosphate salt spray resistant additive 6110 to replace the salt spray resistant additive 142DA in Example 1, and the rest is the same as Example 1.

[0107] Performance Testing

[0108] The coatings prepared in Examples 1-4 and Comparative Examples 1-4 were sprayed on steel plates and other substrates (plastic, electrophoretic base, powder base, smooth machined surface) by air spraying, and the spraying thickness was controlled to be 40±5μm, leveled for 10min, and baked at 60°C for 1h to obtain the coatings, which were then tested. Among them, plastic, electrophoretic base, powder base, and smooth machined surface were only tested for coating adhesion, and other test items were tested for the coatings formed on the steel plates (carbon steel substrates were also tested for adhesion).

[0109] The test items and test reference standards are shown in Table 6.

[0110] Table 6: Test items and test reference standards

[0111] Test items Test reference standards Adhesion GB / T 9286-2021 Cross-cut method hardness GB / T 6739-2022 luster GB / T 9754-2007 Water resistance GB / T 1733-1993 (Method A) Oil resistant GB / T 9274-1988 (Method A) Diesel resistant GB / T 9274-1988 (Method A) <![CDATA[Resistant to 5% H2SO4]]> GB / T 9274-1988 (Method A) Resistant to 5% NaOH GB / T 9274-1988 (Method A) Neutral salt spray resistance GB / T 1771-2007 Artificial aging resistance (Q-Sun) GB / T 1865-2009 Heat and humidity resistance GB / T 1740-2007

[0112] The performance test results of the coatings formed by the coatings of Examples 1-4 and Comparative Examples 1-4 are shown in Table 7.

[0113] Table 7: Performance test results of coatings formed by coatings of Examples 1-4 and Comparative Examples 1-4

[0114]

[0115]

[0116] It can be seen from Table 7 that the coating prepared by the present invention has good adhesion, corrosion resistance, weather resistance, and hardness for a variety of substrates, and can play a good protective role for many substrates.

[0117] The curing agent in Comparative Example 1 was replaced with a commonly used curing agent on the market, which resulted in poor adhesion of the paint film to multiple substrates and was difficult to meet product requirements.

[0118] Comparative Example 2 adjusted the dosage of solid epoxy emulsion and acrylic modified epoxy emulsion. It was found that when the dosage of acrylic modified epoxy emulsion exceeded the dosage of solid epoxy emulsion, the glossiness of the coating decreased, the hardness decreased, and the moisture and heat resistance decreased, making it difficult to meet product requirements.

[0119] Comparative Example 3 uses epoxy resin E44 to replace the epoxy resin E-51 of Example 1, so that the adhesion of the coating of Comparative Example 3 on substrates such as plastic, electrophoretic base, powder base, and smooth machined surface is significantly worse than that of Example 1, that is, the adhesion on multiple substrates is significantly worse than that of Example 1. Comparative Example 3 cannot well meet the actual demand that the engine protective coating must have good adhesion to multiple substrates.

[0120] Comparative Example 4 uses an equal amount of phosphate salt spray resistant additive 6110 to replace the salt spray resistant additive 142DA in Example 1, so that the neutral salt spray resistance performance of Comparative Example 4 is significantly worse than that of Example 1, indicating that the use of specific salt spray resistant additives plays an important role in improving the salt spray resistance of coatings.

[0121] In summary, the present invention utilizes the reaction of epoxy groups with primary amine hydrogen, uses polyamine, bisphenol A epoxy resin, and polyethylene glycol diglycidyl ether as main chain segments, and uses a capping agent for end-capping to prepare an amine curing agent. The introduction of a specific type of epoxy resin can not only improve the compatibility of the amine curing agent and the water-based epoxy emulsion, improve the gloss, but also increase the permeability of the film-forming material, enhance the adhesion to multiple substrates, and combine with other components to make the coating have good anti-corrosion properties.

[0122] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A coating, characterized in that: It includes component A and component B; The component A comprises a water-based epoxy emulsion, a film-forming aid, and a salt spray resistance aid; The B component includes an amine curing agent and an auxiliary agent; The amine curing agent is obtained by using polyamine, bisphenol A epoxy resin, and polyethylene glycol diglycidyl ether as main chain segments and end-capping with an end-capping agent; The epoxy value of the bisphenol A epoxy resin is greater than or equal to 0.48 eq / 100 g.

2. The coating according to claim 1, characterized in that The ratio of the epoxy equivalent in the A component to the active hydrogen equivalent in the B component is (1.1-1.5):

1.

3. The coating according to claim 1, characterized in that The polyamine includes triethylenetetramine; and / or the end-capping agent includes n-butyl glycidyl ether.

4. The coating according to claim 1, characterized in that The aqueous epoxy emulsion includes at least one of a solid epoxy emulsion, a liquid epoxy emulsion, and an acrylic modified epoxy emulsion; when the aqueous epoxy emulsion includes a solid epoxy emulsion and an acrylic modified epoxy emulsion, the amount of the solid epoxy emulsion is greater than the amount of the acrylic modified epoxy emulsion.

5. The coating according to claim 1, characterized in that The component A further comprises at least one of a thickener and water; and / or the component B further comprises water; the auxiliary agent comprises at least one of a defoamer, a wetting agent, a leveling agent, an anti-flash rust auxiliary agent, and a cosolvent.

6. The coating according to claim 5, characterized in that The coating comprises component A and component B; component A comprises water-based epoxy emulsion, film-forming aid, salt spray resistant aid, thickener and water; component B comprises amine curing agent, defoaming agent, wetting agent, leveling agent, anti-flash rust aid, solvent and water; and in parts by mass, component A comprises 65-85 parts of water-based epoxy emulsion, 3.5-5.5 parts of film-forming aid, 0.9-2.2 parts of salt spray resistant aid, 0.9-2.2 parts of thickener and 14-28 parts of water; component B comprises 35-55 parts of amine curing agent, 0.5-1.1 parts of defoaming agent, 0.5-1.1 parts of wetting agent, 0.5-1.1 parts of leveling agent, 2.5-4.5 parts of anti-flash rust aid, 9-16 parts of solvent and 25-45 parts of water.

7. The method for preparing the coating according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) mixing the raw material components of the A component to obtain the A component; (2) The raw material components of the B component are mixed to obtain the B component; and the A component and the B component are mixed to obtain the coating.

8. The preparation method according to claim 7, characterized in that: The preparation method of the amine curing agent comprises the following steps: The polyamine, bisphenol A epoxy resin and polyethylene glycol diglycidyl ether are mixed and reacted for the first time, and then a capping agent is added and reacted for the second time to obtain the amine curing agent.

9. The preparation method according to claim 8, characterized in that: The temperature of the first reaction is 55-75° C., and the time of the first reaction is 3-5 h; and / or, the temperature of the second reaction is 55-75° C., and the time of the second reaction is 1.5-3.5 h.

10. An engine, characterized in that: A coating formed by the coating material according to any one of claims 1 to 6.

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