High-performance water-based acrylic polyurethane coating and preparation method thereof

Abstract

The invention discloses a high-performance water-based acrylic polyurethane coating and a preparation method thereof. The coating is a water-based, double-component and room-temperature self-drying product, and is prepared from a water-based hydroxy acrylic resin dispersion, a diisocyanate polymer, silane, pigment, a cosolvent, water and a functional additive. Due to the adoption of a special monomer, polymerization process, curing agent and assistant compatibility scheme, the obtained coating has few side reactions and long pot life, can be combined with a flash rust resisting agent and an anti-rust pigment for use, and the obtained coating has the advantages of fast hard drying, excellent water resistance, ultraviolet resistance, chemical resistance, corrosion resistance and capability of being attached to multiple base materials, and is a green and environment-friendly anti-corrosion coating product.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a two-component waterborne acrylic polyurethane coating which has the advantages of fast curing, long application period, good initial water resistance, UV resistance, chemical resistance, corrosion resistance, and multi-substrate adhesion, and a preparation method thereof. Background Art

[0002] Two-component waterborne acrylic polyurethane coatings are a type of environmentally friendly protective coatings with waterborne hydroxyl acrylic resins and polyisocyanates as the main film-forming materials. Due to its advantages such as high gloss, weather resistance, gloss and color retention, and anti-sticking, it is widely used in topcoat coating of metal surfaces such as steel structures, engineering vehicles, machinery, and electrical instruments, replacing traditional solvent-based polyurethane coatings to effectively reduce VOC emissions in the coating process.

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

[0004] Commonly used water-based hydroxy acrylic resins are: (1) Hydroxy acrylic emulsion (primary dispersion): usually obtained by emulsion polymerization, its characteristics are simple preparation process, low cost, large molecular weight, less cosolvent, and its prepared polyurethane coating has the advantages of fast drying, high initial hardness, clean odor, low VOC content (usually less than 120g / L). The disadvantage is that the fullness and image clarity of this type of coating are biased, and it is only suitable for general 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, high image clarity decorative coating, while avoiding the coating film defects caused by emulsifier migration. For high hydroxyl value water-based acrylic dispersion, its coating appearance can even be comparable to traditional solvent-based polyurethane coatings. The disadvantage is that the cosolvent content in the dispersion is relatively high, and the environmental protection, odor and drying speed are slightly inferior to the hydroxy acrylic emulsion system.

[0005] Commonly used polyisocyanates are mainly hydrophilically modified diisocyanate polymers (mainly HDI trimer), including polyether modification, sulfonate modification, etc. Hydrophilic modification can effectively improve the dispersibility of the curing agent in the aqueous phase and improve the gloss of the coating, but at the same time it will introduce a large number of polar channels and reduce the protective performance of the coating. Recently, many researchers have proposed the use of hydrophobic polyisocyanates for the preparation of water-based coatings, and have made some progress. The disadvantage is that the hand-stirring properties and vividness of the coating of the hydrophobic polyisocyanate system will be significantly reduced. If used improperly, it will even introduce a large number of microscopic defects, destroying the comprehensive protective performance of the coating.

[0006] Although two-component waterborne acrylic polyurethane coatings have undergone many technological iterations since the 1980s and have made great breakthroughs in application, becoming an important pole in the field of waterborne protective coatings for metals, wood, plastics, etc. However, its shortcomings are still prominent, which greatly restricts the further expansion of this category in high-performance anti-corrosion fields such as ocean, water conservancy, petrochemical, cars, and high-speed rail. Among them, the main technical defects that need to be overcome in two-component waterborne acrylic polyurethane coatings are: (1) The large amount of sulfonate and polyether units introduced by waterborne polyisocyanates make the coating too hydrophilic, and the water resistance and alkali resistance are significantly reduced; (2) In the coating preparation process, isocyanate curing agents are prone to side reactions with water to generate hydrophilic polyureas and carbon dioxide, which introduce defects such as pinholes into the coating; (3) In the high temperature environment in summer, the coating has a short applicable period, and the coating thickens rapidly during the applicable period, which seriously affects the coating quality; (4) The film-forming system has poor compatibility with anti-flash rust agents and anti-rust pigments, and it is impossible to prepare high-quality bottom-to-top integrated anti-corrosion coatings. Summary of the invention

[0007] The invention aims to provide a two-component waterborne acrylic polyurethane coating which has fast curing, long application period, good initial water resistance, UV resistance, chemical resistance, corrosion resistance and can adhere to multiple substrates, and a preparation method thereof.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

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

[0010]

[0011]

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

[0013]

[0014] More preferably, the coating is composed of component A and component B in a mass ratio of (6-10):1: component A is composed of the following ingredients 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 hydroxy acrylic resin dispersion is 41-45wt%, and the hydroxyl content is 2.0-3.0wt%;

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

[0020] S1: Add tertiary carbonate glycidyl ester and mixed monomer solution I into a reaction kettle, heat to 90-120°C, slowly add mixed monomer solution II under stirring, and keep warm for 20-30 minh after adding; then heat to 110-140°C, slowly add mixed monomer solution III, and keep warm for 0.5-1h after adding;

[0021] S2: Cooling to 60-90°C, adding N,N-dimethylethanolamine and triethanolamine to neutralize the resin, stirring for 0.5-1h; then adding water to invert the resin and continue to disperse for 0.5-1h, finally cooling and filtering to obtain a water-based hydroxy acrylic resin dispersion;

[0022] The dosage of each component is as follows:

[0023]

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

[0025] The mixed monomer solution II is composed of the following components by mass: 30-45 parts of styrene, 21-31 parts of methyl methacrylate, 15-25 parts of n-butyl acrylate, 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;

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

[0027] Preferably, the molecular weight of the oligoethylene glycol monomethyl ether monomethacrylate is 500-1000.

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

[0029]

[0030]

[0031] In the technical solution of the present 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 red iron oxide; 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 the present invention, the wetting and dispersing agent in component A is one of Dispers 755W or BYK-190;

[0033] The defoamer is one of Foamex 810 and BYK-044.

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

[0035] The surface additive is DOWSIL 211S;

[0036] The catalyst is Borchers LH10 from Milliken;

[0037] The ultraviolet light absorber is a mixture of Chiguard 5400WB ultraviolet light absorber and Chiguard 101WB light stabilizer, and the mass ratio of the two is 0.1-1:(1-3);

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

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

[0040] In the technical solution of the present 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 Duranate 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 water-based acrylic polyurethane coating comprises the following steps:

[0042] S1: Add water and wetting dispersant to the paint mixing kettle and stir evenly; add pigment, anti-rust pigment, fumed silica, defoamer, and disperse at high speed until there is no powder or agglomeration; transfer the slurry to a sand mill and grind it to a fineness of less than 20μm, add water-based hydroxy acrylic resin dispersion to the slurry and stir evenly; add dipropylene glycol butyl ether, substrate wetting agent, surface additive, catalyst, ultraviolet light absorber, anti-flash rust additive, isothiazolinone fungicide according to the amount, and stir evenly; add rheological additive and adjust the system viscosity to 80-140s (apply 4 cups). Filter to obtain component A;

[0043] S2: Add propylene glycol methyl ether acetate, nylon acid methyl ester, and p-toluenesulfonyl isocyanate into a paint mixing kettle, and stir for 10 to 30 minutes under nitrogen protection. Add isocyanate curing agent and 3-glycidyloxypropyltrimethoxysilane, and stir evenly. Filter to obtain component B.

[0044] S3: Evenly mix component A and component B, and add a small amount of water to dilute, thereby obtaining a water-based acrylic polyurethane coating.

[0045] Beneficial effects of the present invention:

[0046] The two-component water-based acrylic polyurethane coating disclosed in the present invention has the following technical advantages:

[0047] (1) Excellent water resistance of coating: The present invention adopts the internal emulsification scheme of "acrylic acid + oligoethylene glycol monomethyl ether monomethacrylate + 2-acrylamide-2-methylpropane sulfonic acid sodium salt" and the "hydrophobic + hydrophilic modification + silane modification" isocyanate curing agent scheme. This scheme not only obtains good resin phase transition efficiency and curing agent emulsification efficiency, but also effectively reduces the number of hydrophilic units in the coating, and significantly improves the water resistance, alkali resistance and other liquid medium resistance of the water-based acrylic polyurethane coating.

[0048] (2) Fewer side reactions and longer pot life: First, the present invention uses a step-by-step solution polymerization process to anchor the active hydroxyl unit in the hydrophobic region of the polymer chain, and then achieves the embedding of the hydrophilic chain in the hydrophobic chain through internal emulsification, thereby reducing the contact efficiency between the hydroxyl group and the isocyanate group in the aqueous medium environment. Secondly, the use of a curing agent system with hydrophobic polyisocyanate as the main body reduces the exposure of the isocyanate group in the aqueous environment, effectively avoiding the side reaction between the curing agent and water. Thirdly, 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 the hydroxy acrylic dispersion, the resin system disclosed in the present invention has high ion stability and controllable reaction activity, and is not easily impacted by anti-flash rust agents, anti-rust pigments and other components. It can be used to prepare weather-resistant bottom-to-top integrated anti-corrosion coatings with a long application period and high storage stability.

[0050] The high-performance water-based acrylic polyurethane coating disclosed in the present invention has the characteristics of fast drying, long application period, good initial water resistance, UV resistance, chemical resistance, corrosion resistance, and adhesion to multiple substrates. It is a novel two-component self-drying water-based anti-corrosion coating solution. DETAILED DESCRIPTION

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

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

[0053] Digo Dispers 755W:

[0054] https: / / b2b.baidu.com / land?id=471f9d2ef2954d62d1612184d874de4d10

[0055] BYK-190:

[0056] https: / / b2b.baidu.com / land?id=20ae362ebab48d93dd0675148fe6cdd910

[0057] Digo Foamex 810:

[0058] https: / / b2b.baidu.com / land?id=1d39ae52ec3087958732fbd760d4a74c10

[0059] BYK-044:

[0060] https: / / www.boochem.com / xiaopaoji / byk / 044.html

[0061] Digo Wet KL 245:

[0062] https: / / b2b.baidu.com / land?id=ddcdea5c9ae717659dfb75875473fb9a10

[0063] Dow DOWSIL 211S:

[0064] https: / / www.dow.com / en-us / pdp.dowsil-211s-additive.502977z.html#overview

[0065] Milliken Borchers LH10:

[0066] https: / / b2b.baidu.com / land?id=5e885c99fd75adc2df926e9bb1cbd74d10

[0067] Chiguard 5400WB UV absorber:

[0068] http: / / www.gdkyou.com / content / ?404.html

[0069] Chiguard 101WB light stabilizer:

[0070] http: / / www.gdkyou.com / content / ?397.html

[0071] BYK AQUATIX 8421:

[0072] https: / / b2b.baidu.com / land?id=99694b08c9666546ce659f0fffbc023910

[0073] Mingling TAFIGEL PUR 40:

[0074] https: / / b2b.baidu.com / land?id=397817f69cceccd8c48dcd4df8e86fad10

[0075] Dow RM-2020NPR:

[0076] https: / / www.gys.cn / liupingji / 4700850106.html

[0077] Wanhua Aquolin 268:

[0078] https: / / aiqicha.baidu.com / productdetail?pid=30063937305390&productId=da31d5c6c553dc9d608340cf8dd166e5

[0079] Asahi Kasei Duranate TLA-100:

[0080] https: / / b2b.baidu.com / land?id=80c509e2a59d81d93174eb651f92023610

[0081] Covestro Desmodur Z4470 SN:

[0082] https: / / b2b.baidu.com / land?id=22e159034a0483eb3473572248f7ceb610

[0083] The preparation steps of the water-based acrylic polyurethane coatings of Examples 1 to 3 (see Table 1 for material ratios) and Comparative Examples 1 to 4 are as follows (see Table 2 and Table 3 for test results):

[0084] (1) Preparation of water-based hydroxy acrylic resin dispersion:

[0085] Add 55 parts of tertiary carbonate glycidyl ester and 112.2 parts of mixed monomer solution I (including: 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, 5.7 parts of propylene glycol butyl ether) into the reactor, heat to 110°C, and add mixed monomer solution II dropwise under stirring. 177.98 parts (including: 38 parts of styrene, 26.6 parts of methyl methacrylate, 19 parts of n-butyl acrylate, 11.4 parts of isooctyl acrylate, 22.8 parts of hydroxyethyl acrylate, 26.6 parts of hydroxypropyl acrylate, 2.5 parts of dodecyl mercaptan, 6 parts of benzoyl peroxide, 15.2 parts of 100# solvent oil, 9.88 parts of propylene glycol butyl ether), dripping for 2.5 hours, and keeping warm for 0.5 hours; heating to 130°C, continue to drip 162.24 parts of mixed monomer solution III (including: 49.4 parts of methyl methacrylate, 38 parts of n-butyl acrylate, 15.2 parts of acrylic acid, 19 parts of oligoethylene glycol monomethyl ether monomethacrylate (molecular weight of about 500), 17 parts of 2-acrylamido-2-methylpropane sulfonic acid sodium salt, 3.5 parts of benzoyl peroxide, 20.14 parts of propylene glycol methyl ether acetate), dripping for 2 hours, and keeping warm for 1 hour. Cool down to 70℃, add 8 parts of N,N-dimethylethanolamine and 14 parts of triethanolamine to neutralize the resin, and stir for 0.5h. Increase the stirring speed, add 500 parts of water to invert the resin, and add it in 0.5h. After adding, continue to disperse for 0.5h. Cool and filter to obtain a water-based hydroxy acrylic resin dispersion with a hydroxyl content of 2.5wt% and a solid content of 43.4wt%.

[0086] (2) Preparation of water-based acrylic polyurethane coating:

[0087] Add water and Digo Dispers 755W wetting and dispersing agent into the paint mixing kettle and stir evenly; add titanium dioxide, phthalocyanine blue, zinc phosphate, fumed silica, and Digo Foamex 810 defoamer and disperse at high speed until there is no powder or agglomeration. Transfer the slurry into a sand mill and grind it to a fineness of less than 20μm. Add water-based hydroxy acrylic resin dispersion to the slurry and stir evenly; add dipropylene glycol butyl ether, Wet KL 245 substrate wetting agent, Dow DOWSIL 211S surface additive, Milliken Borchers LH10 catalyst, Chiguard 5400WB UV absorber, Chiguard 101WB light stabilizer, Coadd FR-325 anti-flash rust additive, isothiazolinone fungicide and stir evenly; add Dow RM-2020NPR, Mingling TAFIGEL PUR 40 and BYK AQUATIX 8421, and adjust the system viscosity to 80-140s (apply 4 cups). Filter to obtain component A.

[0088] Add propylene glycol methyl ether acetate, nylon acid methyl ester, and p-toluenesulfonyl isocyanate into the paint mixing kettle and stir for 20 minutes under nitrogen protection. Add Wanhua Aquolin 268, Asahi Kasei Duranate TLA-100, Covestro Desmodur Z4470SN and 3-glycidyloxypropyl trimethoxysilane and stir evenly. Filter to obtain component B.

[0089] Mix component A and component B evenly, add a small amount of water to dilute, and then obtain a water-based acrylic polyurethane coating.

[0090] Material ratio of comparative examples 1 to 4:

[0091] Comparative Example 1: Replace the "19 parts of oligoethylene glycol monomethyl ether monomethacrylate (molecular weight of about 500)" in the resin synthesis step of Example 2 with "19 parts of acrylic acid", and the proportions of other materials are the same as those in Example 2.

[0092] Comparative Example 2: The mixed monomers of different components were added step by step in the resin synthesis step of Example 2, and the mixed monomers of the same components were added step by step. The other experimental steps and material ratios were the same as those of Example 2. That is, the synthesis step of "adding tertiary carbonate glycidyl ester and mixed monomer solution I to a reaction kettle, heating to 110°C, adding mixed monomer solution II dropwise under stirring, dripping for 2.5 hours, and keeping warm for 0.5 hours; heating to 130°C, continuing to add mixed monomer solution III dropwise, dripping for 2 hours, and keeping warm for 1 hour" was changed to "adding tertiary carbonate glycidyl ester and 1 / 3 of mixed monomer solution IV to a reaction kettle, heating to 110°C, adding 1 / 3 of mixed monomer solution IV dropwise under stirring, dripping for 2.5 hours, and keeping warm for 0.5 hours; heating to 130°C, continuing to add the remaining mixed monomer solution IV dropwise, dripping for 2 hours, and keeping warm for 1 hour." (Mixed monomer solution IV is a mixture of mixed monomer solutions I, II, and III).

[0093] Comparative Example 3: The "15 parts of Aquolin 268 curing agent and 57 parts of Duranate TLA-100 curing agent" in the coating preparation step of Example 2 are replaced by "72 parts of Aquolin 268 curing agent", and the proportions of other materials are the same as those in Example 2.

[0094] Comparative Example 4: Replace the “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 NALZINFA179 anti-flash rust additive and 0.8 parts of RHEOLATE 299 thickener from Hi-Ming”, and the proportions of other materials are the same as those in Example 3.

[0095] Table 1 Amount of materials added in Examples 1 to 3 (parts by mass)

[0096]

[0097]

[0098] Table 2 Main technical indicators of waterborne acrylic polyurethane coatings in Examples 1 to 3

[0099]

[0100] Note: The dry film thickness of a single coating is 70±5μm; the composite coating consists of a water-based epoxy primer of 80±5μm and a water-based acrylic polyurethane coating of 50±5μm.

[0101] Table 3 Main technical indicators of waterborne acrylic polyurethane coatings of comparative examples 1 to 4

[0102]

[0103]

[0104] The test results show (Table 2) that Examples 1 to 3 all obtained two-component waterborne acrylic polyurethane coatings with fast drying, long application period, good initial water resistance, UV resistance, chemical resistance, corrosion resistance, and multi-substrate adhesion. Example 1 does not add anti-rust pigments and anti-flash rust additives, and can be used as a high-fullness, high-brightness weather-resistant topcoat. Although Examples 2 and 3 add appropriate amounts of anti-rust pigments and anti-flash rust additives, due to the use of resin dispersions with special structures and hydrophobic polyisocyanates, the thermal stability and application period of the resulting coatings are maintained well, and the salt spray resistance is significantly improved, and can be used as a bottom-to-top integrated anti-corrosion coating.

[0105] Among many materials, the monomer composition and segment structure of the hydroxy acrylic acid dispersion are crucial to the stability, compatibility, reactivity and film-forming properties of the coating. The present invention preferably selects the polar monomer combination scheme of "acrylic acid + oligoethylene glycol monomethyl ether monomethacrylate + 2-acrylamide-2-methylpropane sulfonic acid sodium salt". This scheme not only ensures the emulsification performance of the resin system, but also reasonably controls the number of hydrophilic units in the coating. In comparison, if the traditional pure carboxylate phase inversion emulsification scheme (Comparative Example 1) is used, although the phase inversion efficiency of the resin itself will be improved, it will not help the emulsification of the hydrophobic polyisocyanate. At the same time, the number of polar channels of the resulting coating will increase significantly, which is not conducive to the preparation of high-performance anti-corrosion coatings. On the other hand, the step-by-step dripping process of different mixed monomers is another core element of the invention. If all monomers are titrated and polymerized without classification (Comparative Example 2), only random copolymer chains will be obtained. At this time, the hydrophobic unit cannot effectively embed the active hydroxyl group, and the coating has a short application period. At the same time, the hydrophilic units are more dispersed, the overall emulsification efficiency is reduced, and the miscibility with hydrophobic polyisocyanate will also decrease.

[0106] In terms of curing agent design, the "sulfonate modified hexamethylene diisocyanate trimer + hexamethylene diisocyanate trimer + isophorone diisocyanate trimer" solution can ensure dispersibility while taking into account drying rate, application period and water resistance. If the traditional pure hydrophilic curing agent solution (Comparative Example 3) is used, although the glossiness of the coating will be improved, the application period and protective performance (especially water resistance) will be reduced to varying degrees.

[0107] In terms of additive selection, anti-flash rust additives and rheological additives have the most significant impact on the adaptation period of two-component waterborne acrylic polyurethane coatings. If improperly selected (Comparative Example 4), the coating will thicken rapidly during the applicable period, thereby destroying the workability of the product. In severe cases, it will also affect the adhesion of the coating and produce coating defects such as bubbles and pinholes.

[0108] Finally, the other materials disclosed in the present invention are also selected after a large number of experiments, and any replacement will affect the comprehensive performance of the coating. For example, the preferred Borchers LH10 catalyst, Chiguard 5400WB ultraviolet absorber, Chiguard101WB light stabilizer and 3-glycidyloxypropyltrimethoxysilane, etc., any replacement will reduce the stability, dryness, adhesion and gloss and color retention of the coating.

Claims

1. A high performance waterborne acrylic polyurethane coating, characterized in that The coating is composed of component A and component B in a mass ratio of (6-10):1: Component A consists of the following ingredients by mass: Component B consists of the following ingredients by mass:

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

3. The high performance waterborne acrylic polyurethane coating according to claim 1, characterized in that The solid content of the aqueous hydroxy acrylic resin dispersion is 41-45 wt %, and the hydroxy content is 2.0-3.0 wt %; Preferably, the aqueous hydroxylated acrylic resin dispersion is prepared by the following steps: S1: Add tertiary carbonate glycidyl ester and mixed monomer solution I into a reaction kettle, heat to 90-120°C, slowly add mixed monomer solution II under stirring, and keep warm for 20-30 minh after adding; then heat to 110-140°C, slowly add mixed monomer solution III, and keep warm for 0.5-1h after adding; S2: Cooling to 60-90°C, adding N,N-dimethylethanolamine and triethanolamine to neutralize the resin, stirring for 0.5-1h; then adding water to invert the resin and continue to disperse for 0.5-1h, finally cooling and filtering to obtain a water-based hydroxy acrylic resin dispersion; The dosage of each component is as follows: The mixed monomer solution I is composed of the following components by mass: 25-35 parts of styrene, 21-31 parts of methyl methacrylate, 6-18 parts of n-butyl acrylate, 5-10 parts of isooctyl acrylate, 5-10 parts of hydroxyethyl acrylate, 8-15 parts of hydroxypropyl acrylate, 1-4 parts of dodecyl mercaptan, 8-13 parts of 100# solvent oil and 3-9 parts of propylene glycol butyl ether; The mixed monomer solution II is composed of the following components by mass: 30-45 parts of styrene, 21-31 parts of methyl methacrylate, 15-25 parts of n-butyl acrylate, 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 by mass: 10-25 parts of acrylic acid, 45-55 parts of methyl methacrylate, 30-45 parts of n-butyl acrylate, 10-30 parts of oligoethylene glycol monomethyl ether monomethacrylate, 10-30 parts of 2-acrylamido-2-methylpropane sulfonic acid sodium salt, 2-8 parts of benzoyl peroxide, and 15-30 parts of propylene glycol methyl ether acetate; Preferably, the molecular weight of the oligoethylene glycol monomethyl ether monomethacrylate is 500-1000.

4. The high performance waterborne acrylic polyurethane coating according to claim 3, characterized in that 5. 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 red iron oxide; the anti-rust pigment is one or more of zinc phosphate, aluminum tripolyphosphate, zinc phosphomolybdate, and zinc strontium phosphate.

6. The high performance waterborne acrylic polyurethane coating according to claim 1, characterized in that: The wetting and dispersing agent in component A is one of Digo Dispers 755W or BYK BYK-190; The defoamer is one of Foamex 810 and BYK-044. The substrate wetting agent is Digo Wet KL 245; The surface additive is DOWSIL 211S; The catalyst is Borchers LH10 from Milliken; The ultraviolet light absorber is a mixture of Chiguard 5400WB ultraviolet light absorber and Chiguard 101WB light stabilizer, and the mass ratio of the two is 0.1-1:(1-3); The anti-flash rust additive is Coadd FR-325; The rheological additive is a mixture of an associative polyurethane thickener and a modified ethylene-vinyl acetate copolymer wax emulsion. Preferably, the rheological additive is a mixture of Dow RM-2020NPR, Mingling TAFIGEL PUR 40 and BYK AQUATIX 8421, and the mass ratio of the three is 0.1-1:(0.1-0.5):(1-3).

7. The high performance waterborne acrylic polyurethane coating according to claim 1, characterized in that: 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 Duranate TLA-100 and Covestro Desmodur Z4470 SN, and the mass ratio of the three is 10-20:(50-65):(0.1-1).

8. A method for preparing the high-performance waterborne acrylic polyurethane coating according to claim 1, characterized in that: The method comprises the following steps: S1: Add water and wetting dispersant to the paint mixing kettle and stir evenly; add pigment, anti-rust pigment, fumed silica, defoamer, and disperse at high speed until there is no powder or agglomeration; transfer the slurry to a sand mill and grind it to a fineness of less than 20μm, add water-based hydroxy acrylic resin dispersion to the slurry and stir evenly; add dipropylene glycol butyl ether, substrate wetting agent, surface additive, catalyst, ultraviolet light absorber, anti-flash rust additive, isothiazolinone fungicide according to the amount, and stir evenly; add rheological additive and adjust the system viscosity to 80-140s (apply 4 cups). Filter to obtain component A; S2: Add propylene glycol methyl ether acetate, nylon acid methyl ester, and p-toluenesulfonyl isocyanate into a paint mixing kettle, and stir for 10 to 30 minutes under nitrogen protection. Add isocyanate curing agent and 3-glycidyloxypropyltrimethoxysilane, and stir evenly. Filter to obtain component B. S3: Mix component A and component B evenly, and add a small amount of water to dilute, so as to obtain a water-based acrylic polyurethane coating.

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