Water-based two-component polyurethane finish paint with ultra-long service life and preparation method of water-based two-component polyurethane finish paint

Abstract

The invention discloses a water-based two-component polyurethane finish paint with an ultra-long service life and a preparation method thereof, and belongs to the technical field of paints.The water-based two-component polyurethane finish paint with the ultra-long service life is characterized in that the water-based two-component polyurethane finish paint with the ultra-long service life comprises a component A and a component B according to the weight ratio of (4-7): 1, the component A is prepared from the following components in percentage by weight: 60 to 70 percent of water-based hydroxy acrylic resin, 1.1 to 1.7 percent of water-based dispersing agent, 0.2 to 0.5 percent of organic silicon defoaming agent, 8 to 12 percent of pigment, 4 to 5 percent of filler, 12 to 14 percent of deionized water, 4 to 6 percent of cosolvent, 0.1 to 0.2 percent of flatting agent, 0.2 to 0.3 percent of wetting agent and 0.2 to 0.3 percent of thickening agent; the hydroxyl content of the water-based hydroxyl acrylic resin is 2.2 to 4.0 percent; the component A is water-based resin, the component B is an isocyanate curing agent, and the equivalent weight of NCO in the isocyanate curing agent is 11.5-12.5%. According to the polyurethane finishing paint, the matching of the water-based resin and the isocyanate curing agent is adjusted, so that the polyurethane finishing paint has different service lives, especially under the condition that the air temperature is higher than 30 DEG C in summer.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, in particular to a water-based two-component polyurethane topcoat with an extremely long service life and a preparation method thereof. Background Art

[0002] In the field of coatings, water-based paints have achieved significant development in recent years. Using water as the dispersion medium, they disperse film-forming substances, additives, and fillers in water to form a uniform mixture. The emergence of this type of coating is of great significance. On the one hand, it reduces costs. On the other hand, since it does not contain volatile organic solvents, it greatly reduces environmental pollution. Moreover, it is non-flammable, making transportation and storage more convenient. Therefore, it has attracted widespread attention and application. As a key type of water-based coating, water-based two-component polyurethane topcoat has excellent weather resistance and is suitable for coating various transportation vehicles and construction machinery. Its paint film is smooth and flat, and it has good decorative and protective properties. It plays an important role in practical applications. As various industries continue to increase their requirements for coating quality and environmental protection, the market demand for water-based two-component polyurethane topcoat is also growing, driving the continuous advancement and innovation of related technologies.

[0003] In the prior art, in order to meet the coating requirements of different scenarios, there are a variety of conventional solutions for water-based two-component polyurethane topcoats. Generally, traditional water-based two-component polyurethane topcoats are composed of component one, which is composed of hydroxyl acrylic resin, pigment, additives and solvents, and aliphatic isocyanate as component two. In actual use, these two components are mixed and formulated according to a certain ratio to form a coating that can be sprayed. During the formulation process, appropriate raw materials and processes are selected based on the characteristics of the product and the requirements of use to ensure the basic performance of the coating. For example, when selecting hydroxyl acrylic resin, its chemical properties and physical properties are considered to ensure compatibility with other ingredients and the stability of the coating. At the same time, there are also strict controls on the amount and type of additives and solvents added to achieve the desired coating effect. In addition, during the production process, stirring, mixing and other processes are also used to ensure the uniformity of the coating.

[0004] However, existing traditional water-based two-component polyurethane topcoats have significant drawbacks. The prepared coating will solidify after a short period of storage at high temperatures (e.g., 2 hours at 35°C). This necessitates frequent mixing for large-scale spraying operations, significantly reducing application efficiency and limiting its scope of application. Furthermore, due to its short shelf life, excess paint cannot be used promptly, resulting in waste and increased costs. Summary of the Invention

[0005] In order to solve the problems in the prior art, the present invention provides a water-based two-component polyurethane topcoat with an ultra-long service life and a preparation method thereof. By adjusting the combination of water-based resin and isocyanate curing agent, the present application can make the polyurethane topcoat have different service life. Especially in summer when the temperature is greater than 30°C, it can also meet the paint mixing time and spraying time of on-site construction. In addition, the polyurethane topcoat is not easy to gel and is not easy to clog pipeline equipment, making it easy to clean the equipment.

[0006] The first aspect of the present invention is to provide a water-based two-component polyurethane topcoat with an extremely long service life, which adopts the following technical solution: A water-based two-component polyurethane topcoat with an extremely long service life comprises a component A and a component B in a weight ratio of (4-7):1, wherein the component A comprises, by weight percentage, 60-70% of a water-based hydroxy acrylic resin, 1.1-1.7% of a water-based dispersant, 0.2-0.5% of an organosilicon defoamer, 8-12% of a pigment, 4-5% of a filler, 12-14% of deionized water, 4-6% of a cosolvent, 0.1-0.2% of a leveling agent, 0.2-0.3% of a wetting agent, and 0.2-0.3% of a thickener; The hydroxyl content of the water-based hydroxylated acrylic resin is 2.2-4.0%; The component B is an isocyanate curing agent, and the NCO equivalent of the isocyanate curing agent is 11.5-12.5%.

[0007] By adopting the above technical solution, rationally proportioning component A and component B and the content of each component, controlling the hydroxyl content of the water-based hydroxy acrylic resin and the NCO content of the isocyanate curing agent, the service life of the topcoat can be effectively extended, the frequent mixing during large-area spraying can be reduced, construction efficiency can be improved, and paint waste and cost increase can be reduced. At the same time, the excellent weather resistance, smooth and flat paint film characteristics, and good decorative and protective properties of the water-based two-component polyurethane topcoat can be retained.

[0008] Preferably, the water-based hydroxy acrylic resin is prepared by reacting methyl methacrylate, butyl acrylate, styrene, HPMA and HEMA.

[0009] By adopting the above technical solution, it is stipulated that the water-based hydroxy acrylic resin of component A is formed by the reaction of methyl methacrylate, butyl acrylate, styrene, HPMA and HEMA. The performance of the water-based hydroxy acrylic resin is further optimized on the basis of the original ultra-long service life of the topcoat, which helps to improve the stability of the entire topcoat system, so that the topcoat can better maintain its performance during storage and use, thereby extending its service life, reducing the frequent mixing problems caused by paint curing, improving construction efficiency, and reducing paint waste and costs.

[0010] Preferably, based on weight percentage, the total amount of methyl methacrylate, butyl acrylate and styrene is 70-85%, HPMA is 0-10%, and HEMA is 15-25%.

[0011] By adopting the above technical solution, the present application controls the hydroxyl content of the water-based hydroxylated acrylic resin between 2.2-4.0% by limiting the addition amount of HPMA and HEMA. At the same time, the introduction of HPMA reduces the reaction rate of the water-based hydroxylated acrylic resin with the isocyanate curing agent, thereby making the obtained polyurethane topcoat have an ultra-long service life.

[0012] Preferably, the water-based acrylic resin is obtained by the following preparation method: after heating the solvent to 120±1°C, a monomer composed of methyl methacrylate, butyl acrylate, styrene, HPMA, and HEMA, an initiator, and a chain transfer agent are added dropwise, and the addition is completed within 3-4 hours. Immediately after the addition is completed, a mixture of acrylic acid and an initiator is added dropwise, and the addition is completed within 0.5 hours, and the mixture is kept warm for 50-60 minutes to obtain the water-based acrylic resin.

[0013] Preferably, the cosolvent consists of ethylene glycol butyl ether and dipropylene glycol butyl ether in a weight ratio of (1-2):1.

[0014] By adopting the above technical solution, in a water-based two-component polyurethane topcoat with an extremely long service life, using ethylene glycol butyl ether and dipropylene glycol butyl ether in a specific weight ratio as a cosolvent helps to better dissolve and disperse other components, thereby ensuring that the components of the topcoat are evenly dispersed, ensuring the performance of the topcoat, and maintaining a long service life of the water-based two-component polyurethane topcoat.

[0015] Preferably, the thickener is a polyurethane associative thickener.

[0016] By adopting the above technical solution, when a polyurethane associative thickener is selected as the thickener, it can not only give the topcoat excellent construction fluidity, but also form a network structure under static conditions through the reversible association of hydrophobic groups with emulsion ions and pigments and fillers to prevent sedimentation or sagging. Moreover, its curing reaction with isocyanate has no chemical conflict and will not hinder the curing of the paint film.

[0017] Preferably, the isocyanate curing agent is one of IPDI curing agent and HDI curing agent.

[0018] The second aspect of the present invention is to provide a method for preparing the above-mentioned water-based two-component polyurethane topcoat with an ultra-long service life, wherein component B does not need to be prepared, and component A includes the following preparation steps: S1. Mixing water-based hydroxy acrylic resin and deionized water (60% of the total amount of deionized water) and adding water-based dispersant and organosilicon defoamer under low-speed stirring for 5-10 minutes; S2. Add pigment and filler to step S1 under medium-speed stirring and stir and disperse until there is no dry powder on the liquid surface, stir and disperse under high-speed stirring for 30-35 minutes, then soak for 55-60 minutes, and stir for another 10-15 minutes; S3, grinding the mixed material obtained in S2, adding the remaining deionized water to the mixed material and grinding until the fineness of the mixed material is less than 20 μm, and then stopping the grinding; S4. Add a cosolvent, a leveling agent, and a wetting agent to the ground mixture, stir at a medium speed for 15-20 minutes, then add a thickener and stir until evenly mixed to obtain component A.

[0019] Preferably, the low-speed stirring rate is 300-500 rpm, the medium-speed stirring rate is 1000-1500 rpm, and the high-speed stirring rate is 2000-3000 rpm.

[0020] By adopting the above technical solution, when different stirring rates are selected for mixing different raw materials, it can be ensured that the materials are fully mixed and dispersed in different stirring stages, thereby ensuring the storage performance of the water-based polyurethane topcoat.

[0021] In summary, the present invention has the following beneficial effects: This application effectively reduces the reaction rate of hydroxyl and NCO by controlling the hydroxyl content in the water-based acrylic resin and the NCO content in the isocyanate curing agent, thereby being able to adjust the service life of the polyurethane topcoat according to the usage scenario, especially in summer when the temperature is greater than 30°C, while still being able to meet the paint mixing time and spraying time required for on-site construction, thereby improving construction efficiency, not being prone to clogging pipeline equipment, and facilitating equipment cleaning. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below with reference to the examples. All reagents without manufacturer's indication are conventional reagents that can be purchased commercially.

[0023] Preparation Example 1 A method for preparing a water-based hydroxylated acrylic resin comprises the following steps: Propylene glycol butyl ether and versatate glycidyl carbonate are mixed in a volume ratio of 1:1 and heated to 120±1°C. Then, a monomer composed of a mixture of methyl methacrylate, butyl acrylate, styrene, HPMA, and HEMA, an initiator (60% of the total initiator), and a chain transfer agent are added dropwise, and the addition is completed within 3 hours. Immediately after the addition is completed, a mixture composed of acrylic acid (the amount of acrylic acid is 0.01% of the total monomer amount) and the remaining initiator is added dropwise, and the addition is completed within 0.5 hours. The mixture is kept warm for 50 minutes to obtain a water-based hydroxy acrylic resin; wherein the total amount of the monomers is 85% of methyl methacrylate, butyl acrylate, and styrene, 0% of HPMA, and 15% of HEMA, and the weight ratio of methyl methacrylate, butyl acrylate, and styrene is 2:2:1. The initiator azobisisobutyronitrile is 1% of the total monomer amount, and the chain transfer agent tert-dodecyl mercaptan is 0.5% of the total monomer amount. The hydroxyl content of the finally obtained water-based hydroxy acrylic resin is approximately 2.2%.

[0024] Preparation Example 2 A method for preparing a water-based hydroxylated acrylic resin comprises the following steps: Propylene glycol butyl ether and versatate glycidyl ester are mixed in a volume ratio of 1:1 and heated to 120±1°C. Then, a monomer composed of a mixture of methyl methacrylate, butyl acrylate, styrene, HPMA, and HEMA, an initiator (60% of the total initiator), and a chain transfer agent are added dropwise, and the addition is completed within 4 hours. Immediately after the addition is completed, a mixture composed of acrylic acid (the amount of acrylic acid is 0.01% of the total monomer amount) and the remaining initiator is added dropwise, and the addition is completed within 0.5 hours. The mixture is kept warm for 60 minutes to obtain a water-based hydroxy acrylic resin; wherein the total amount of monomers is 75% of methyl methacrylate, butyl acrylate, and styrene, 0% of HPMA, and 25% of HEMA, and the weight ratio of methyl methacrylate, butyl acrylate, and styrene is 2:2:1. The initiator azobisisobutyronitrile is 1% of the total monomer amount, and the chain transfer agent tert-dodecyl mercaptan is 0.5% of the total monomer amount. The hydroxyl content of the finally obtained water-based hydroxy acrylic resin is approximately 3.6%.

[0025] Preparation Example 3 A method for preparing a water-based hydroxylated acrylic resin comprises the following steps: After mixing propylene glycol butyl ether and versatate glycidyl carbonate in a volume ratio of 1:1 and heating to 120±1°C, a monomer composed of a mixture of methyl methacrylate, butyl acrylate, styrene, HPMA, and HEMA, an initiator (60% of the total initiator) and a chain transfer agent are added dropwise, and the addition is completed within 4 hours. Immediately after the addition is completed, a mixture composed of acrylic acid (the amount of acrylic acid is 0.01% of the total monomer amount) and the remaining initiator is added dropwise, and the addition is completed within 0.5 hours, and the mixture is kept warm for 60 minutes to obtain a water-based hydroxy acrylic resin; wherein the total amount of monomers is 75% of methyl methacrylate, butyl acrylate, and styrene, 10% of HPMA, and 15% of HEMA, and the weight ratio of methyl methacrylate, butyl acrylate, and styrene is 2:2:1. The initiator azobisisobutyronitrile is 1% of the total monomer amount, and the chain transfer agent tert-dodecyl mercaptan is 0.5% of the total monomer amount. The hydroxyl content in the finally obtained water-based hydroxy acrylic resin is approximately 3.5%.

[0026] Preparation Example 4 A method for preparing a water-based hydroxylated acrylic resin comprises the following steps: Propylene glycol butyl ether and versatate glycidyl carbonate are mixed in a volume ratio of 1:1 and heated to 120±1°C. Then, a monomer composed of a mixture of methyl methacrylate, butyl acrylate, styrene, HPMA, and HEMA, an initiator (60% of the total initiator), and a chain transfer agent are added dropwise, and the addition is completed within 4 hours. Immediately after the addition is completed, a mixture composed of acrylic acid (the amount of acrylic acid is 0.01% of the total monomer amount) and the remaining initiator is added dropwise, and the addition is completed within 0.5 hours. The mixture is kept warm for 60 minutes to obtain a water-based hydroxy acrylic resin; wherein the total amount of monomers, calculated by percentage, is 72% of methyl methacrylate, butyl acrylate, and styrene, 8% of HPMA, and 20% of HEMA. The weight ratio of methyl methacrylate, butyl acrylate, and styrene is 2:2:1. The initiator azobisisobutyronitrile is 1% of the total monomer amount, and the chain transfer agent tert-dodecyl mercaptan is 0.5% of the total monomer amount. The hydroxyl content of the finally obtained water-based hydroxy acrylic resin is approximately 4.0%.

[0027] Example 1 A method for preparing a water-based two-component polyurethane topcoat with an extremely long service life, wherein component B does not require preparation and component A comprises the following preparation steps: S1. 6.5 kg of the water-based hydroxylated acrylic resin obtained in Preparation Example 1 and 7.86 kg of deionized water were stirred and mixed at a rate of 300 rpm. 1.5 kg of the aqueous dispersant BYKK190 and 0.3 kg of the silicone defoamer BYK028 were added and stirred for 10 minutes. S2. Add 10.6 kg of pigment and 4 kg of filler barium sulfate to step S1 with stirring at a speed of 1000 rpm, stir and disperse until there is no dry powder on the liquid surface, stir and disperse at a speed of 2000 rpm for 35 minutes, then soak for 55 minutes, and stir for another 10 minutes; S3, grinding the mixture obtained in S2, adding the remaining 5.24 kg of deionized water to the mixture and grinding until the fineness of the mixture is less than 20 μm; S4. Add 5 kg of cosolvent, 0.1 kg of leveling agent BYK333, and 0.2 kg of wetting agent Digo 4100 to the ground mixture, stir at 1000 rpm for 20 minutes, then add 0.2 kg of polyurethane associative thickener and stir until evenly mixed to obtain component A; wherein the cosolvent is composed of ethylene glycol butyl ether and dipropylene glycol butyl ether in a weight ratio of 1:1; When in use, take the above-mentioned component A and component B and mix them in a weight ratio of 4:1, wherein component B is an anionic water-based isocyanate curing agent modified based on IPDI trimer, with an NCO equivalent of 12±0.5% and a solid content of 70%.

[0028] Example 2 A method for preparing a water-based two-component polyurethane topcoat with an extremely long service life, wherein component B does not require preparation and component A comprises the following preparation steps: S1. 6.0 kg of the water-based hydroxylated acrylic resin obtained in Preparation Example 1 and 8.4 kg of deionized water were stirred and mixed at a rate of 400 rpm. 1.7 kg of the aqueous dispersant BYKK190 and 0.5 kg of the silicone defoamer BYK028 were added and stirred for 5 minutes. S2. Add 12 kg of pigment and 5 kg of filler barium sulfate to step S1 with stirring at a rate of 1000 rpm, stir and disperse until there is no dry powder on the liquid surface, stir and disperse at a speed of 2500 rpm for 30 minutes, then soak for 60 minutes, and stir for another 15 minutes; S3, grinding the mixture obtained in S2, adding the remaining 5.6 kg of deionized water to the mixture and grinding until the fineness of the mixture is less than 20 μm; S4. Add 6 kg of cosolvent, 0.2 kg of leveling agent BYK333, and 0.3 kg of wetting agent Digo 4100 to the ground mixture, stir at 1500 rpm for 15 minutes, then add 0.3 kg of polyurethane associative thickener and stir until evenly mixed to obtain component A; wherein the cosolvent is composed of ethylene glycol butyl ether and dipropylene glycol butyl ether in a weight ratio of 1:1.5; When in use, take the above-mentioned component A and component B and mix them in a weight ratio of 4:1, wherein component B is an anionic water-based isocyanate curing agent modified based on IPDI trimer, with an NCO equivalent of 12±0.5% and a solid content of 70%.

[0029] Example 3 A method for preparing a water-based two-component polyurethane topcoat with an extremely long service life, wherein component B does not require preparation and component A comprises the following preparation steps: S1. After mixing 7 kg of the water-based hydroxylated acrylic resin obtained in Preparation Example 1 and 7.2 kg of deionized water, 1.1 kg of aqueous dispersant BYKK190 and 0.2 kg of silicone defoamer BYK028 were added at a stirring rate of 500 rpm and stirred for 5 minutes. S2. Add 8 kg of pigment and 4 kg of filler barium sulfate to step S1 at a stirring rate of 1500 rpm and stir and disperse until there is no dry powder on the liquid surface. Then stir and disperse at a speed of 3000 rpm for 30 minutes, then soak for 60 minutes, and stir for another 10 minutes. S3, grinding the mixture obtained in S2, adding the remaining 4.8 kg of deionized water to the mixture and grinding until the fineness of the mixture is less than 20 μm; S4. Add 4 kg of cosolvent, 0.1 kg of leveling agent BYK333, and 0.3 kg of wetting agent Digo 4100 to the ground mixture, stir at 1000 rpm for 20 minutes, then add 0.3 kg of polyurethane associative thickener and stir until evenly mixed to obtain component A; wherein the cosolvent is composed of ethylene glycol butyl ether and dipropylene glycol butyl ether in a weight ratio of 1:2; When in use, take the above-mentioned component A and component B and mix them in a weight ratio of 4:1, wherein component B is an anionic water-based isocyanate curing agent modified based on IPDI trimer, with an NCO equivalent of 12±0.5% and a solid content of 70%.

[0030] Example 4.1 A method for preparing a water-based two-component polyurethane topcoat with an extremely long service life, which differs from Example 1 in that the water-based hydroxy acrylic resin is obtained in Preparation Example 2 of the water-based hydroxy acrylic resin, and the rest is the same as Example 1.

[0031] Example 4.2 A method for preparing a water-based two-component polyurethane topcoat with an extremely long shelf life, which differs from Example 4.1 in that an isocyanate curing agent is an HDI curing agent, the NCO equivalent is 14±0.5%, and the solid content is 70%. All other aspects are the same as Example 4.1.

[0032] Example 5.1 A method for preparing a water-based two-component polyurethane topcoat with an extremely long service life, which differs from Example 1 in that the water-based hydroxy acrylic resin is obtained in Preparation Example 3 of the water-based hydroxy acrylic resin, and the rest is the same as Example 1.

[0033] Example 5.2 A method for preparing a water-based two-component polyurethane topcoat with an extremely long shelf life, which differs from Example 5.1 in that an HDI curing agent is used as the isocyanate curing agent, the NCO equivalent is 14±0.5%, and the solid content is 70%. All other aspects are the same as Example 5.1.

[0034] Example 6.1 A method for preparing a water-based two-component polyurethane topcoat with an extremely long service life, which differs from Example 1 in that the water-based hydroxy acrylic resin is obtained in Preparation Example 4 of the water-based hydroxy acrylic resin, and the rest is the same as Example 1.

[0035] Example 6.2 A method for preparing a water-based two-component polyurethane topcoat with an extremely long shelf life, which differs from Example 6.1 in that an HDI curing agent is used as the isocyanate curing agent, the NCO equivalent is 14±0.5%, and the solid content is 70%. All other aspects are the same as Example 6.1.

[0036] Example 7.1 A method for preparing a water-based two-component polyurethane topcoat with an extremely long service life, which differs from Example 1 in that component A and component B are mixed in a weight ratio of 7:1, and all other aspects are the same as Example 1.

[0037] Example 7.2 A method for preparing a water-based two-component polyurethane topcoat with an extremely long service life, which differs from Example 1 in that component A and component B are mixed in a weight ratio of 7:1, component B uses an HDI curing agent with an NCO equivalent of 14±0.5% and a solid content of 70%, and all other conditions are the same as Example 1.

[0038] Performance testing After the topcoat prepared in the above example was prepared, the viscosity was adjusted to 60s / 35°C (the viscosity was tested according to the 4-cup coating method in GB / T1723-1993) and then placed in a sealed peeling bottle. The glass bottle was placed in an environment with an air temperature of 35°C. The viscosity change was tested every 1 hour. The experiment was terminated when the topcoat became lumpy or solidified. The test results are shown in Table 1.

[0039] Table 1 Test results of topcoat usage time As can be seen from the above table, the use time of water-based acrylic resins with different hydroxyl contents after being mixed with curing agents is very different. For example, in Examples 1-3 and Examples 7.1-7.2 of the present application, when the hydroxyl content of the water-based acrylic resin is 2.2%, the topcoats obtained in Examples 1-3 and Example 7 can be prepared into a uniformly flowing liquid without gelling for 24 hours (but the viscosity exceeds the 4-cup range), with an extremely long use life and convenient construction.

[0040] The hydroxyl content of the water-based acrylic resin in Examples 4.1-4.2 is about 3.6%, and the hydroxyl content of the water-based acrylic resin in Examples 5.1-5.2 is about 3.5%. The difference between the two is not much, but there is a significant difference in the storage time. Example 4.1 gelled after 3 hours of storage, and Example 4.2 gelled after 2.5 hours of storage. Both Examples 5.1 and 5.2 were cured after 5 hours of storage. The reason for the difference is that there is no HPMA monomer in the preparation of the water-based hydroxylated acrylic resin in Example 4. Since the hydroxyl groups in HPMA are secondary hydroxyl groups and the hydroxyl groups in HEMA are primary hydroxyl groups, the reaction rate of the hydroxyl groups in HPMA with NCO is lower than that of the hydroxyl groups in HEMA. Therefore, the curing rate of Example 5 is significantly lower than that of Example 4.

[0041] In Examples 6.1-6.2, when the hydroxyl content in the water-based acrylic resin is about 4.0%, the curing rate of the topcoat is very fast and the storage time is very short. Therefore, the present application can match water-based acrylic resins with different hydroxyl contents according to construction requirements, thereby improving the convenience of construction.

[0042] The embodiments of this specific implementation method are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A water-based two-component polyurethane topcoat with an extremely long service life, characterized by: The invention comprises component A and component B in a weight ratio of (4-7):1, wherein the component A comprises, by weight percentage, 60-70% of a water-based hydroxy acrylic resin, 1.1-1.7% of a water-based dispersant, 0.2-0.5% of an organosilicon defoamer, 8-12% of a pigment, 4-5% of a filler, 12-14% of deionized water, 4-6% of a cosolvent, 0.1-0.2% of a leveling agent, 0.2-0.3% of a wetting agent, and 0.2-0.3% of a thickener; The hydroxyl content of the waterborne hydroxylated acrylic resin is 2.2-4.0%; The component B is an isocyanate curing agent, and the NCO equivalent of the isocyanate curing agent is 11.5-12.5%.

2. The water-based two-component polyurethane topcoat with an ultra-long service life according to claim 1, characterized in that: The water-based hydroxy acrylic resin is prepared by reacting methyl methacrylate, butyl acrylate, styrene, HPMA and HEMA.

3. The water-based two-component polyurethane topcoat with an ultra-long service life according to claim 2, characterized in that: In terms of weight percentage, the total amount of methyl methacrylate, butyl acrylate and styrene is 70-85%, HPMA is 0-10%, and HEMA is 15-25%.

4. The water-based two-component polyurethane topcoat with an ultra-long service life according to claim 2, characterized in that: The water-based acrylic resin is obtained by the following preparation method: after heating a solvent to 120±1° C., a monomer composed of methyl methacrylate, butyl acrylate, styrene, HPMA, and HEMA, an initiator, and a chain transfer agent are added dropwise, and the addition is completed within 3-4 hours. After the addition is completed, a mixture of acrylic acid and an initiator is immediately added dropwise, and the addition is completed within 0.5 hours, and the mixture is kept warm for 50-60 minutes to obtain the water-based acrylic resin.

5. The water-based two-component polyurethane topcoat with an ultra-long service life according to claim 1, characterized in that: The cosolvent consists of ethylene glycol butyl ether and dipropylene glycol butyl ether in a weight ratio of (1-2):

1.

6. The water-based two-component polyurethane topcoat with an ultra-long service life according to claim 1, characterized in that: The thickener is a polyurethane associative thickener.

7. The water-based two-component polyurethane topcoat with an ultra-long service life according to claim 1, characterized in that: The isocyanate curing agent is one of IPDI curing agent and HDI curing agent.

8. A method for preparing a water-based two-component polyurethane topcoat with an ultra-long service life according to any one of claims 1 to 7, characterized in that: The A component comprises the following preparation steps: S1. Mix water-based hydroxy acrylic resin and deionized water (60% of the total amount of deionized water) and add water-based dispersant and organosilicon defoamer under low-speed stirring for 5-10 minutes; S2. Add pigment and filler to step S1 under medium-speed stirring and stir and disperse until there is no dry powder on the liquid surface, stir and disperse under high-speed stirring for 30-35 minutes, then soak for 55-60 minutes, and stir for another 10-15 minutes; S3, grinding the mixed material obtained in S2, adding the remaining deionized water to the mixed material and grinding until the fineness of the mixed material is less than 20 μm, and then stopping the grinding; S4. Add a cosolvent, a leveling agent, and a wetting agent to the ground mixture, stir at a medium speed for 15-20 minutes, then add a thickener and stir until evenly mixed to obtain component A.

9. The method for preparing a water-based two-component polyurethane topcoat with an ultra-long service life according to claim 8, characterized in that: The low-speed stirring rate is 300-500 rpm, the medium-speed stirring rate is 1000-1500 rpm, and the high-speed stirring rate is 2000-3000 rpm.

Images