High performance waterborne acrylic polyurethane coating and method of making same

Abstract

The application discloses a high-performance water-based acrylic polyurethane coating and a preparation method thereof. The coating is a water-based, two-component and room-temperature self-drying product, which is composed of a water-based hydroxyl acrylic resin dispersion, a diisocyanate polymer, silane, pigments, a cosolvent, water and functional additives. Due to the adoption of special monomers, polymerization processes, curing agents and additive compounding schemes, the obtained coating has less side reactions, a long applicable period, can be combined with anti-flash rust agents and anti-rust pigments, and the obtained coating layer has the advantages of fast actual drying, excellent water resistance, ultraviolet resistance, chemical resistance, corrosion resistance and multi-substrate adhesion, and is a green and environment-friendly anti-corrosion coating product.

Description

A high-performance waterborne acrylic polyurethane coating and its preparation method Technical Field

[0001] This invention relates to the field of coating technology, specifically to a two-component waterborne acrylic polyurethane coating and its preparation method, which features fast drying, long pot life, good initial water resistance, UV resistance, chemical resistance, corrosion resistance, and adhesion to multiple substrates. Background Technology

[0002] Two-component waterborne acrylic polyurethane coatings are a type of environmentally friendly protective coating that uses waterborne hydroxyl acrylic resin and polyisocyanate as the main film-forming agents. Due to their numerous advantages such as high gloss, weather resistance, gloss and color retention, and anti-tack properties, they are widely used for topcoat application on metal surfaces such as steel structures, engineering vehicles, machinery, and electrical instruments, effectively reducing VOC emissions in the coating process by replacing traditional solvent-based polyurethane coatings.

[0003] In the design process of two-component waterborne acrylic polyurethane coatings, the selection of hydroxyl acrylic resin and polyisocyanate is particularly crucial.

[0004] Commonly used waterborne hydroxyl acrylic resins include: (1) Hydroxy acrylic emulsion (primary dispersion): usually obtained by emulsification polymerization. Its characteristics are simple preparation process, low cost, large molecular weight, and low co-solvent. The polyurethane coatings formulated with it have advantages such as fast drying, high initial hardness, low odor, and low VOC content (usually less than 120g / L). The disadvantage is that the fullness and vividness of this type of coating are poor, and it is only suitable for ordinary protection and decoration. (2) Hydroxy acrylic dispersion (secondary dispersion): usually prepared by solution polymerization, neutralization and phase inversion. Its characteristics are internal emulsification, small resin molecular weight, good compatibility with a variety of curing agents, easy to obtain high gloss and high vividness decorative coatings, and avoid the coating defects caused by emulsifier migration. For high hydroxyl value waterborne acrylic dispersions, the appearance of the coating can even be comparable to traditional solvent-based polyurethane coatings. The disadvantage is that the co-solvent content in the dispersion is high, and the environmental protection, odor and drying speed are slightly inferior to the hydroxyl acrylic emulsion system.

[0005] Commonly used polyisocyanates are mainly hydrophilically modified diisocyanate polymers (primarily HDI trimers), including polyether-modified and sulfonate-modified varieties. Hydrophilic modification can effectively improve the dispersibility of the curing agent in the aqueous phase and increase coating gloss, but it also introduces a large number of polar channels, reducing the protective performance of the coating. Recently, many researchers have proposed using hydrophobic polyisocyanates for the preparation of waterborne coatings, achieving some progress. However, the drawback is that the hand-stirring properties and coating sharpness of hydrophobic polyisocyanate systems are significantly reduced, and improper use can even introduce numerous microscopic defects, compromising the overall protective performance of the coating.

[0006] Although two-component waterborne acrylic polyurethane coatings have undergone multiple technological iterations since the 1980s and have achieved great breakthroughs in application, becoming an important force in the field of waterborne protective coatings for metals, wood, and plastics, their shortcomings are still quite prominent, which greatly restricts the further expansion of this type of product in high-performance anti-corrosion fields such as marine, hydraulic engineering, petrochemical, automobiles, and high-speed rail. Among them, the technical defects of two-component waterborne acrylic polyurethane coatings that urgently need to be overcome are: (1) The large amount of sulfonate and polyether units introduced by waterborne polyisocyanate makes the coating too hydrophilic, and the water resistance and alkali resistance are significantly reduced; (2) In the coating formulation process, isocyanate curing agents are prone to side reactions with water, generating hydrophilic polyurea and carbon dioxide, which introduce defects such as pinholes into the coating; (3) In the high temperature environment of summer, the coating has a short service life, and the coating thickens rapidly during the service life, which seriously affects the coating quality; (4) The film-forming system has poor compatibility with anti-flash rust agents and anti-rust pigments, making it impossible to prepare high-quality topcoat integrated anti-corrosion coatings. Summary of the Invention

[0007] The purpose of this invention is to provide a two-component waterborne acrylic polyurethane coating and its preparation method, which has the advantages of fast drying, long pot life, good initial water resistance, UV resistance, chemical resistance, corrosion resistance, and adhesion to multiple substrates.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] A high-performance waterborne acrylic polyurethane coating is composed of component A and component B in a mass ratio of (6-10):1. Component A consists of the following components by mass:

[0010]

[0011]

[0012] Component B consists of the following ingredients by mass:

[0013]

[0014] Further preferably, the coating is composed of component A and component B in a mass ratio of (6-10):1: component A consists of the following components by mass:

[0015]

[0016] Component B consists of the following ingredients by mass:

[0017]

[0018] In the technical solution of the present invention, the solid content of the aqueous hydroxyl acrylic resin dispersion is 41-45 wt%, and the hydroxyl content is 2.0-3.0 wt%.

[0019] Preferably, the aqueous hydroxyl acrylic resin dispersion is prepared by the following steps:

[0020] S1: Add glycidyl tert-carbonate and mixed monomer solution I to the reactor, heat to 90-120°C, slowly add mixed monomer solution II while stirring, and keep warm for 20-30 min after the addition is complete; then heat to 110-140°C, slowly add mixed monomer solution III, and keep warm for 0.5-1 h after the addition is complete.

[0021] S2: Cool to 60-90℃, add N,N-dimethylethanolamine and triethanolamine to neutralize the resin, and stir for 0.5-1h; then add water to invert the resin and continue to disperse for 0.5-1h, and finally cool and filter to obtain the waterborne hydroxyl acrylic resin dispersion;

[0022] The specific dosages of each component are as follows:

[0023]

[0024] The mixed monomer solution I is composed of the following components by mass: 25-35 parts styrene, 21-31 parts methyl methacrylate, 6-18 parts n-butyl acrylate, 5-10 parts isooctyl acrylate, 5-10 parts hydroxyethyl acrylate, 8-15 parts hydroxypropyl acrylate, 1-4 parts dodecyl mercaptan, 8-13 parts 100# solvent oil, and 3-9 parts propylene glycol butyl ether.

[0025] The mixed monomer solution II is composed of the following components by mass: 30-45 parts styrene, 21-31 parts methyl methacrylate, 15-25 parts n-butyl acrylate, 6-17 parts isooctyl acrylate, 18-26 parts hydroxyethyl acrylate, 20-30 parts hydroxypropyl acrylate, 1.5-5 parts dodecyl mercaptan, 3-10 parts benzoyl peroxide, 10-20 parts 100# solvent oil, and 6-15 parts propylene glycol butyl ether.

[0026] The mixed monomer solution III is composed of the following components by mass: 10-25 parts acrylic acid, 45-55 parts methyl methacrylate, 30-45 parts n-butyl acrylate, 10-30 parts oligomeric polyethylene glycol monomethyl ether monomethyl acrylate, 10-30 parts sodium 2-acrylamido-2-methylpropane sulfonate, 2-8 parts benzoyl peroxide, and 15-30 parts propylene glycol methyl ether acetate.

[0027] Preferably, the molecular weight of the oligomeric polyethylene glycol monomethyl ether monomethacrylate is 500 to 1000.

[0028] Preferably, the components of the aqueous hydroxyl acrylic resin dispersion are as follows:

[0029]

[0030]

[0031] In the technical solution of this invention, the pigment is one or more of rutile titanium dioxide, pigment red 170, pigment red 254, pigment yellow 154, pigment yellow 83, pigment yellow 151, phthalocyanine blue, phthalocyanine green, carbon black, and iron oxide red; the anti-rust pigment is one or more of zinc phosphate, aluminum tripolyphosphate, zinc phosphomolybdate, and zinc strontium phosphate.

[0032] In the technical solution of this invention, the wetting and dispersing agent in component A is either Dispers 755W or BYK-190.

[0033] The defoamer is either Teco Foamex 810 or BYK-044;

[0034] The substrate wetting agent is Tigo Wet KL 245;

[0035] The surface additive is Dow DOWSIL 211S;

[0036] The catalyst is Milliken Borchers LH10.

[0037] The ultraviolet light absorber is a mixture of Chiguard 5400WB ultraviolet absorber and Chiguard 101WB light stabilizer, with a mass ratio of 0.1 to 1:(1 to 3).

[0038] The anti-flash rust additive is Coadd FR-325;

[0039] The rheology modifier is a mixture of an associative polyurethane thickener and a modified ethylene-vinyl acetate copolymer wax emulsion. Preferably, the rheology modifier is a mixture of Dow RM-2020NPR, Mingling TAFIGEL PUR 40 and BYK AQUATIX 8421, with a mass ratio of 0.1-1:(0.1-0.5):(1-3).

[0040] In the technical solution of this invention, the isocyanate curing agent in component B is a mixture of sulfonate-modified hexamethylene diisocyanate trimer, hexamethylene diisocyanate trimer and isophorone diisocyanate trimer; preferably, the isocyanate curing agent is a mixture of Wanhua Aquolin 268, Asahi Kasei Durnate TLA-100 and Covestro Desmodur Z4470 SN, and the mass ratio of the three is 10-20:(50-65):(0.1-1).

[0041] A method for preparing the above-mentioned high-performance waterborne acrylic polyurethane coating, the method comprising the following steps:

[0042] S1: Add water and wetting / dispersing agent to the paint mixing tank and stir until homogeneous; add pigment, anti-rust pigment, fumed silica, and defoamer, and disperse at high speed until no lumps or agglomerates are present; transfer the slurry to a sand mill and grind until the fineness is less than 20μm; add the waterborne hydroxyl acrylic resin dispersion to the slurry and stir until homogeneous; add dipropylene glycol butyl ether, substrate wetting agent, surface additives, catalyst, ultraviolet absorber, anti-flash rust additive, and isothiazolinone bactericide according to the requirements, and stir until homogeneous; add rheology modifier and adjust the system viscosity to 80-140s (Ford cup 4). Filter to obtain component A;

[0043] S2: Add propylene glycol methyl ether acetate, methyl nylonate, and p-toluenesulfonyl isocyanate to a paint mixing tank and stir for 10–30 min under nitrogen protection. Add isocyanate curing agent and 3-glycidyl etheroxypropyltrimethoxysilane and stir until homogeneous. Filter to obtain component B.

[0044] S3: Mix component A and component B evenly, and dilute with a small amount of water to obtain water-based acrylic polyurethane coating.

[0045] The beneficial effects of this invention are:

[0046] The two-component waterborne acrylic polyurethane coating disclosed in this invention has the following technical advantages:

[0047] (1) Excellent water resistance of the coating: This invention adopts an internal emulsification scheme of "acrylic acid + oligoethylene glycol monomethyl ether monomethacrylate + sodium 2-acrylamido-2-methylpropane sulfonate" and an isocyanate curing agent scheme of "hydrophobic + hydrophilic modification + silane modification". This scheme not only achieves good resin phase inversion efficiency and curing agent emulsification efficiency, but also effectively reduces the number of hydrophilic units in the coating, significantly improving the water resistance, alkali resistance and other liquid media resistance properties of the waterborne acrylic polyurethane coating.

[0048] (2) Fewer side reactions and longer pot life: First, this invention uses a stepwise solution polymerization process to anchor active hydroxyl units in the hydrophobic region of the polymer chain, and then uses internal emulsification to embed the hydrophilic chain into the hydrophobic chain, reducing the contact efficiency between hydroxyl groups and isocyanate groups in an aqueous environment. Second, the use of a curing agent system based on hydrophobic polyisocyanate reduces the exposure of isocyanate groups in the aqueous environment, effectively avoiding side reactions between the curing agent and water. Third, the use of a composite rheological system of "associative polyurethane thickener + modified ethylene-vinyl acetate copolymer wax emulsion" improves the viscosity stability of the coating during its pot life.

[0049] (3) Good compatibility with anti-flash rust agents and anti-rust pigments: Due to the special structural design of hydroxy acrylic dispersion, the resin system disclosed in this invention has high ionic stability and controllable reactivity. It is not easily affected by anti-flash rust agents, anti-rust pigments and other components, and can be used to prepare weather-resistant topcoat anti-corrosion coatings with long service life and high storage stability.

[0050] The high-performance waterborne acrylic polyurethane coating disclosed in this invention has the characteristics of fast drying, long pot life, good initial water resistance, UV resistance, chemical resistance, corrosion resistance, and adhesion to multiple substrates. It is a novel two-component self-drying waterborne anti-corrosion coating solution. Detailed Implementation

[0051] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto:

[0052] The sources of some of the raw materials in this embodiment of the invention are as follows:

[0053] Tigo Dispers 755W:

[0054] BYK-190:

[0055] Teco Foamex 810:

[0056] BYK-044:

[0057] DIG HOT KL 245:

[0058] Dow DOWSIL 211S:

[0059] Borchers LH10 (Mericken Borchers):

[0060] Chiguard 5400WB UV absorber:

[0061] Chiguard 101WB light stabilizer:

[0062] BYK AQUATIX 8421:

[0063] Mingling TAFIGEL PUR 40:

[0064] Dow RM-2020NPR:

[0065] Wanhua Aquolin 268:

[0066] Asahi Kasei Duranate TLA-100:

[0067] Covestro Desmodur Z4470 SN:

[0068] The preparation steps of waterborne acrylic polyurethane coatings in Examples 1-3 (material ratios are shown in Table 1) and Comparative Examples 1-4 are as follows (test results are shown in Tables 2 and 3):

[0069] (1) Preparation of aqueous hydroxyl acrylic resin dispersion:

[0070] Add 55 parts of glycidyl tert-carbonate and 112.2 parts of mixed monomer solution I (containing: 30.4 parts of styrene, 26.6 parts of methyl methacrylate, 11.4 parts of n-butyl acrylate, 7.6 parts of isooctyl acrylate, 7.6 parts of hydroxyethyl acrylate, 11.4 parts of hydroxypropyl acrylate, 2 parts of dodecyl mercaptan, 9.5 parts of 100# solvent oil, and 5.7 parts of propylene glycol butyl ether) to the reaction vessel, heat to 110°C, and add mixed monomer solution II dropwise while stirring. 177.98 parts (containing: 38 parts styrene, 26.6 parts methyl methacrylate, 19 parts n-butyl acrylate, 11.4 parts isooctyl acrylate, 22.8 parts hydroxyethyl acrylate, 26.6 parts hydroxypropyl acrylate, 2.5 parts dodecyl mercaptan, 6 parts benzoyl peroxide, 15.2 parts 100# solvent oil, and 9.88 parts propylene glycol butyl ether) were added dropwise over 2.5 hours, and kept at the temperature for 0.5 hours. The temperature was then raised to 130°C, and 162.24 parts of mixed monomer solution III (containing: 49.4 parts methyl methacrylate, 38 parts n-butyl acrylate, 15.2 parts acrylic acid, 19 parts oligomeric polyethylene glycol monomethyl ether monomethyl acrylate (molecular weight around 500), 17 parts sodium 2-acrylamido-2-methylpropane sulfonate, 3.5 parts benzoyl peroxide, and 20.14 parts propylene glycol methyl ether acetate) were added dropwise over 2 hours, and kept at the temperature for 1 hour. The temperature was lowered to 70℃, and 8 parts of N,N-dimethylethanolamine and 14 parts of triethanolamine were added to neutralize the resin, and the mixture was stirred for 0.5 h. The stirring speed was increased, and 500 parts of water were added to initiate phase inversion of the resin, which was completed over 0.5 h. After the addition was complete, dispersion was continued for another 0.5 h. After cooling and filtration, an aqueous hydroxyl acrylic resin dispersion with a hydroxyl content of 2.5 wt% and a solid content of 43.4 wt% was obtained.

[0071] (2) Preparation of waterborne acrylic polyurethane coatings:

[0072] Add water and Dispers 755W wetting and dispersing agent to the paint mixing tank and stir until homogeneous. Add titanium dioxide, phthalocyanine blue, zinc phosphate, fumed silica, and Foamex 810 defoamer, and disperse at high speed until there are no lumps or agglomerates. Transfer the slurry to a sand mill and grind it to a fineness of less than 20 μm. Add the aqueous hydroxyl acrylic resin dispersion to the slurry and stir until homogeneous. Add dipropylene glycol butyl ether, Tigo Wet KL 245 substrate wetting agent, Dow DOWSIL 211S surface additive, Merrick Borchers LH10 catalyst, Chiguard 5400WB UV absorber, Chiguard 101WB light stabilizer, Coadd FR-325 anti-flash rust additive, and isothiazolinone bactericide, and stir until homogeneous. Add Dow RM-2020NPR, Mingling TAFIGEL PUR 40, and BYK AQUATIX 8421, adjusting the system viscosity to 80–140 s (Ford cup 4). Filter to obtain component A.

[0073] Propylene glycol methyl ether acetate, methyl nylonate, and p-toluenesulfonyl isocyanate were added to a paint mixing tank and stirred for 20 minutes under nitrogen protection. Wanhua Aquolin 268, Asahi Kasei Durnate TLA-100, Covestro Desmodur Z4470SN, and 3-glycidyl etheroxypropyltrimethoxysilane were then added and stirred until homogeneous. The mixture was filtered to obtain component B.

[0074] Mix component A and component B evenly, and dilute with a small amount of water to obtain water-based acrylic polyurethane coating.

[0075] Material proportions for comparative examples 1-4:

[0076] Comparative Example 1: In the resin synthesis step of Example 2, "19 parts of oligoethylene glycol monomethyl ether monomethacrylate (molecular weight about 500)" was replaced with "19 parts of acrylic acid", and the proportions of the remaining materials were the same as in Example 2.

[0077] Comparative Example 2: The stepwise addition of mixed monomers of different components in the resin synthesis process of Example 2 was changed to the stepwise addition of mixed monomers of the same components. The remaining experimental steps and material ratios were the same as in Example 2. That is, the process of adding glycidyl carbonate and mixed monomer solution I to the reactor, heating to 110°C, adding mixed monomer solution II dropwise under stirring for 2.5 hours, and holding for 0.5 hours; heating to 130°C, and continuing to add mixed monomer solution III dropwise for 2 hours, and holding for 1 hour was changed to adding glycidyl carbonate and 1 / 3 of mixed monomer solution IV to the reactor, heating to 110°C, adding 1 / 3 of mixed monomer solution IV dropwise under stirring for 2.5 hours, and holding for 0.5 hours; heating to 130°C, and continuing to add the remaining mixed monomer solution IV dropwise for 2 hours, and holding for 1 hour. (Mixed monomer solution IV is a mixture of mixed monomer solutions I, II, and III).

[0078] Comparative Example 3: In the coating preparation step of Example 2, “15 parts of Aquolin 268 curing agent and 57 parts of Duranate TLA-100 curing agent” were replaced with “72 parts of Aquolin 268 curing agent”, and the proportions of the remaining materials were the same as in Example 2.

[0079] Comparative Example 4: Replace "0.8 parts of Coadd FR-325 anti-flash rust additive, 0.8 parts of RM-2020NPR thickener, 0.2 parts of TAFIGEL PUR 40 thickener, and 2 parts of AQUATIX 8421 wax emulsion" in Example 3 with "0.8 parts of Nalzin FA179 anti-flash rust additive and 0.8 parts of RHEOLATE 299 thickener", and keep the other material ratios the same as in Example 3.

[0080] Table 1. Material addition amounts (parts by mass) for Examples 1-3

[0081]

[0082] Table 2 Main technical indicators of waterborne acrylic polyurethane coatings in Examples 1-3

[0083]

[0084]

[0085] Note: The dry film thickness of a single coating is 70±5μm; the composite coating consists of an 80±5μm waterborne epoxy primer and a 50±5μm waterborne acrylic polyurethane coating.

[0086] Table 3 Main technical indicators of waterborne acrylic polyurethane coatings for comparative examples 1-4

[0087]

[0088]

[0089] Test results (Table 2) show that Examples 1-3 all yielded two-component waterborne acrylic polyurethane coatings with fast drying time, long pot life, good initial water resistance, UV resistance, chemical resistance, corrosion resistance, and adhesion to multiple substrates. Example 1, without the addition of rust-inhibiting pigments and anti-flash rust additives, can be used as a high-fullness, high-brightness weather-resistant topcoat. Although Examples 2 and 3 added appropriate amounts of rust-inhibiting pigments and anti-flash rust additives, due to the use of a specially structured resin dispersion and hydrophobic polyisocyanate, the resulting coatings maintained good thermal stability and pot life, while significantly improving salt spray resistance, making them suitable for use as a combined topcoat and primer anti-corrosion coating.

[0090] Among various materials, the monomer composition and chain segment structure of hydroxyl acrylic acid dispersions are crucial to the stability, compatibility, reactivity, and film-forming properties of coatings. This invention preferentially employs a polar monomer combination of "acrylic acid + oligoethylene glycol monomethyl ether monomethacrylate + sodium 2-acrylamido-2-methylpropane sulfonate". This scheme ensures both the emulsifying performance of the resin system and rationally controls the number of hydrophilic units within the coating. In contrast, if a traditional pure carboxylate phase inversion emulsification scheme is used (Comparative Example 1), although the resin's own phase inversion efficiency is improved, it does little to help emulsify the hydrophobic polyisocyanate. Simultaneously, the number of polar channels in the resulting coating increases significantly, which is detrimental to the preparation of high-performance anti-corrosion coatings. Furthermore, the stepwise dropwise addition process of different mixed monomers is another core element of this invention. If all monomers are titrated and polymerized without differentiation (Comparative Example 2), only random copolymer chains will be obtained. In this case, the hydrophobic units cannot effectively encapsulate the active hydroxyl groups, resulting in a short pot life for the coating. Meanwhile, the hydrophilic units are more dispersed, resulting in a lower overall emulsification efficiency and a decrease in miscibility with hydrophobic polyisocyanates.

[0091] Regarding the curing agent design, the "sulfonate-modified hexamethylene diisocyanate trimer + hexamethylene diisocyanate trimer + isophorone diisocyanate trimer" scheme can ensure dispersibility while also considering drying rate, pot life, and water resistance. If a traditional pure hydrophilic curing agent scheme (Comparative Example 3) is used, although the gloss of the coating will be improved, the pot life and protective performance (especially water resistance) will be reduced to varying degrees.

[0092] In terms of additive selection, anti-flash rust additives and rheology modifiers have the most significant impact on the settling-time of two-component waterborne acrylic polyurethane coatings. Improper selection (Comparative Example 4) can cause the coating to thicken rapidly within its settling-time, thereby compromising the product's workability. In severe cases, it can also affect coating adhesion and cause coating defects such as bubbles and pinholes.

[0093] Finally, the other materials disclosed in this invention were also selected through extensive experimentation, and arbitrary substitution will affect the overall performance of the coating. For example, the preferred Borchers LH10 catalyst, Chiguard 5400WB ultraviolet absorber, Chiguard 101WB light stabilizer, and 3-glycidyl etheroxypropyltrimethoxysilane, etc., will reduce the stability, drying time, adhesion, and gloss and color retention of the coating if arbitrarily substituted.

Claims

1. A high-performance waterborne acrylic polyurethane coating, characterized in that: This coating is composed of component A and component B in a mass ratio of (6~10):

1. Component A, by mass, consists of the following ingredients: 30~85 parts water-based hydroxyl acrylic resin dispersion, 10~45 parts pigment, 0~10 parts anti-rust pigment, 0.1~5 parts fumed silica, 1~10 parts dipropylene glycol butyl ether, 0.1~5 parts wetting and dispersing agent, 0.01~1 parts defoamer, 0.1~1 parts substrate wetting agent, 0.1~2 parts surface additives, and 0.1~1 parts catalyst. 0.5-5 parts anti-flash rust additive, 0-1.5 parts isothiazolinone bactericide, 0.1-0.5 parts rheology modifier, 0.1-5 parts water, 5-25 parts; Component B consists of the following components by mass: 60-90 parts isocyanate curing agent, 1-7 parts 3-glycidyl ether oxypropyltrimethoxysilane, 0.5-4 parts p-toluenesulfonyl isocyanate, 1-35 parts propylene glycol methyl ether acetate, 1-35 parts methyl nylonate; The isocyanate curing agent is a mixture of Wanhua Aquolin 268, Asahi Kasei Durnate TLA-100 and Covestro Desmodur Z4470 SN, with a mass ratio of 10-20:(50-65):(0.1-1).

2. The high-performance waterborne acrylic polyurethane coating according to claim 1, characterized in that: This coating is composed of component A and component B in a mass ratio of (6~10):

1. Component A, by mass, consists of the following ingredients: 45~70 parts water-based hydroxyl acrylic resin dispersion, 15~30 parts pigment, 0 or 2~6 parts rust-preventive pigment, 0.1~1 part fumed silica, 2~5 parts dipropylene glycol butyl ether, 1~3 parts wetting and dispersing agent, 0.01~0.5 parts defoamer, 0.1~0.5 parts substrate wetting agent, 0.1~1 parts surface additives, and 0.1 part catalyst. ~0.6 parts UV absorber 1.5~5 parts anti-flash rust additive 0 or 0.1~1 parts isothiazolinone bactericide 0.1~0.3 parts rheology modifier 1~5 parts water 5~15 parts; Component B, by mass, consists of the following components: isocyanate curing agent 65~85 parts 3-glycidyl ether oxypropyltrimethoxysilane 1~5 parts p-toluenesulfonyl isocyanate 0.5~2 parts propylene glycol methyl ether acetate 1~15 parts methyl nylonate 8~15 parts.

3. The high-performance waterborne acrylic polyurethane coating according to claim 1, characterized in that: The aqueous hydroxyl acrylic resin dispersion has a solid content of 41-45 wt% and a hydroxyl content of 2.0-3.0 wt%.

4. The high-performance waterborne acrylic polyurethane coating according to claim 3, characterized in that: The aqueous hydroxyl acrylic resin dispersion is prepared by the following steps: S1: Add glycidyl tert-carbonate and mixed monomer solution I to a reactor, heat to 90-120 °C, slowly add mixed monomer solution II while stirring, and keep warm for 20-30 min after addition; then heat to 110-140 °C, slowly add mixed monomer solution III, and keep warm for 0.5-1 h after addition; S2: Cool to 60-90 °C, add N,N-dimethylethanolamine and triethanolamine to neutralize the resin, stir for 0.5-1 h; then add water to invert the resin and continue dispersion for 0.5-1 h, finally cool and filter to obtain the aqueous hydroxyl acrylic resin dispersion; the specific amounts of each component are as follows: glycidyl tert-carbonate 30-100 parts, mixed monomer solution I 100-120 parts, mixed monomer solution II 150-200 parts, mixed monomer solution III 140-210 parts N,N-dimethylethanolamine, 4-12 parts triethanolamine, 6-20 parts water; 450-550 parts water; the mixed monomer solution I, by mass, consists of the following components: 25-35 parts styrene, 21-31 parts methyl methacrylate, 6-18 parts n-butyl acrylate, 5-10 parts isooctyl acrylate, 5-10 parts hydroxyethyl acrylate, 8-15 parts hydroxypropyl acrylate, 1-4 parts dodecyl mercaptan, 8-13 parts 100# solvent oil, and 3-9 parts propylene glycol butyl ether; the mixed monomer solution II, by mass, consists of the following components: 30-45 parts styrene, 21-31 parts methyl methacrylate, 15-20 parts n-butyl acrylate, and 450-550 parts water. The mixed monomer solution III comprises, by mass, 25 parts of acrylic acid, 6-17 parts of isooctyl acrylate, 18-26 parts of hydroxyethyl acrylate, 20-30 parts of hydroxypropyl acrylate, 1.5-5 parts of dodecyl mercaptan, 3-10 parts of benzoyl peroxide, 10-20 parts of 100# solvent oil, and 6-15 parts of propylene glycol butyl ether; the mixed monomer solution III is composed of the following components: 10-25 parts of acrylic acid, 45-55 parts of methyl methacrylate, 30-45 parts of n-butyl acrylate, 10-30 parts of oligomeric polyethylene glycol monomethyl ether monomethyl acrylate, 10-30 parts of sodium 2-acrylamido-2-methylpropane sulfonate, 2-8 parts of benzoyl peroxide, and 15-30 parts of propylene glycol methyl ether acetate.

5. The high-performance waterborne acrylic polyurethane coating according to claim 4, characterized in that: The molecular weight of the oligomeric polyethylene glycol monomethyl ether monomethacrylate is 500-1000.

6. The high-performance waterborne acrylic polyurethane coating according to claim 4, characterized in that: The specific amounts of each component used in the preparation of the aqueous hydroxyl acrylic resin dispersion are as follows: 40-60 parts of glycidyl tert-carbonate, 100-120 parts of mixed monomer solution I, 160-190 parts of mixed monomer solution II, 140-180 parts of mixed monomer solution III, 4-12 parts of N,N-dimethylethanolamine, 10-20 parts of triethanolamine, and 480-520 parts of water.

7. The high-performance waterborne acrylic polyurethane coating according to claim 1, characterized in that: The pigment is one or more of rutile titanium dioxide, pigment red 170, pigment red 254, pigment yellow 154, pigment yellow 83, pigment yellow 151, phthalocyanine blue, phthalocyanine green, carbon black, and iron oxide red; the anti-rust pigment is one or more of zinc phosphate, aluminum tripolyphosphate, zinc phosphomolybdate, and zinc strontium phosphate.

8. The high-performance waterborne acrylic polyurethane coating according to claim 1, characterized in that: The wetting and dispersing agent in component A is either Dispers 755W or BYK-190; the defoamer is either Foamex 810 or BYK-044; the substrate wetting agent is Wet KL 245; the surface additive is Dow DOWSIL 211S; the catalyst is Borchers LH10; the ultraviolet absorber is a mixture of Chiguard 5400WB ultraviolet absorber and Chiguard 101WB light stabilizer, with a mass ratio of 0.1~1:(1~3); the anti-flash rust additive is Coadd FR-325; and the rheology modifier is a mixture of associative polyurethane thickener and modified ethylene-vinyl acetate copolymer wax emulsion.

9. The high-performance waterborne acrylic polyurethane coating according to claim 8, characterized in that: The rheology modifier is a mixture of Dow RM-2020NPR, Mingling TAFIGEL PUR 40 and BYK AQUATIX 8421, with a mass ratio of 0.1~1:(0.1~0.5):(1~3).

10. A method for preparing the high-performance waterborne acrylic polyurethane coating according to claim 1, characterized in that: The method includes the following steps: S1: Add water and wetting and dispersing agent to the paint mixing tank and stir evenly; add pigment, anti-rust pigment, fumed silica, and defoamer, and disperse at high speed until there are no lumps or agglomerates; transfer the slurry to a sand mill and grind it to a fineness of less than 20 μm; add waterborne hydroxyl acrylic resin dispersion to the slurry and stir evenly; add dipropylene glycol butyl ether, substrate wetting agent, surface additive, catalyst, ultraviolet absorber, anti-flash rust additive, and isothiazolinone bactericide, and stir evenly; add rheology modifier and adjust the viscosity of the system to 80~140 s (Copper Cup 4); filter to obtain component A; S2: Add propylene glycol methyl ether acetate, methyl nylonate, and p-toluenesulfonyl isocyanate to the paint mixing tank and stir for 10~30 seconds under nitrogen protection. min; Add isocyanate curing agent and 3-glycidyl etheroxypropyltrimethoxysilane, stir evenly; filter to obtain component B; S3: Mix component A and component B evenly, add a small amount of water to dilute, and obtain waterborne acrylic polyurethane coating.

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