Water-based high-workability polyurethane finish paint and application thereof

Abstract

The invention relates to a water-based polyurethane finish paint with high construction performance. The coating is composed of a component A and a component B, the component A comprises aliphatic polycarbonate modified waterborne polyurethane emulsion, an ultra-high molecular weight dispersing agent, a flatting agent and a defoaming agent; and the component B comprises polyether modified isocyanate and a cosolvent. The aliphatic polycarbonate modified waterborne polyurethane emulsion and the polyether modified isocyanate are used as matrix resin, so that a coating film and a base material have excellent adhesive force, water resistance and yellowing resistance, and the drying rate of the coating film can be increased; by adding a special modified nanoscale material, a coating film has good hardness, chemical resistance, weather resistance and the like. According to the invention, roller painting and spraying of the waterborne polyurethane finish paint are realized, the special modified nanoscale material is used for the first time to improve the mechanical property, weather resistance, wear resistance, medium resistance and the like of the paint film, and the purpose of reducing the product cost can be achieved on the basis of improving the product performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of waterborne polyurethane topcoats for roller coating and spray coating, and relates to a waterborne polyurethane topcoat with high construction performance composed of aliphatic polycarbonate modified waterborne polyurethane emulsion, polyether modified isocyanate, ultra-high molecular weight dispersant, leveling agent, defoamer, special modified nano-grade materials and the like, and a preparation method thereof. Background Art

[0002] It is a general trend for the coatings industry to implement source substitution of low-VOCs coatings. For example, product structure adjustment (water-based coatings, etc.) is one of the important measures. However, water-based coatings are sensitive to the choice of construction methods, and it is difficult to achieve the use of two or more construction methods. Therefore, it is necessary to increase the technical innovation of water-based coatings and improve their construction tolerance.

[0003] The water-based high-construction-performance polyurethane topcoat of the present invention is actually designed to achieve high construction performance of the polyurethane topcoat while meeting the requirements of environmental protection policies. It can be used for both roller coating and spray coating, and can prepare light-colored coating films by applying special modified nano-scale material technology, providing a basis for the colorization of the topcoat.

[0004] 1. The cross-linking reaction of aliphatic polycarbonate-modified waterborne polyurethane emulsion and polyether-modified isocyanate is used to greatly improve the adhesion between the topcoat and the middlecoat, so that the prepared paint film has excellent mechanical properties, chemical stability and wear resistance; and the increase in molecular weight accelerates the drying rate of the coating and shortens the construction time.

[0005] 2. The selection of ultra-high molecular weight dispersant greatly improves the dispersibility and stability of pigments and fillers in the system, making the water-based polyurethane topcoat have a better anti-settling effect.

[0006] 3. The reasonable combination of ultra-high molecular weight dispersants, leveling agents, defoaming agents, etc. can reduce the occurrence of defects such as foaming and shrinkage during construction, and realize the use of roller coating and spraying.

[0007] 4. By adding specially modified nano-scale materials, the system's mechanical properties, corrosion resistance, media resistance, scrub resistance, wear resistance, weather resistance and storage stability are greatly improved. Summary of the invention

[0008] The purpose of the present invention is to realize the water-based polyurethane topcoat, ensure that it has good construction performance in the application of engineering machinery, etc., and can meet the requirements of roller coating and spray coating processes at the same time; and the specially modified nano-grade material is a light-colored system, and can be matched with different pigments to prepare a colored topcoat. It is composed of component A and component B; component A is composed of aliphatic polycarbonate modified water-based polyurethane emulsion, ultra-high molecular weight dispersant, leveling agent, defoamer, special modified nano-grade material, etc.; component B is composed of polyether modified isocyanate, cosolvent, etc.

[0009] To achieve the above purpose, the present invention discloses the following technical contents: A water-based polyurethane topcoat with high construction performance, characterized in that the coating is composed of the following raw materials in parts by weight: Component A 90-100 B component 15-20 Main raw material ratio of component A (1) Preparation of white water slurry Deionized water 20.9 Silicone defoamer Tego 810 0.5 Ultra high molecular weight dispersant SV-295 8.0 Titanium dioxide R-706 27 Special modified nano-scale materials 32 Aqueous precipitated barium sulfate 11 Multifunctional additive AMP-95 0.6 (2) Dilution of defoaming agent Tego 901W 30 Deionized water 70 (3) Dilution of neutralizer Multifunctional additive AMP-95 10 Deionized water 90 (4) Harmony Aliphatic polycarbonate modified waterborne polyurethane emulsion 40-50 Deionized water 0-10 Main raw material ratio (2) Diluted defoamer Tego 901W 1.0-1.5 2-5-Diethylene glycol butyl ether 1-3 Dipropylene glycol butyl ether Wetting agent Tego 270 0.3-0.5 Wetting and leveling agent BYK 3455 0.1-0.3 Main raw material ratio (1) Dispersed white water slurry 40-50 The ratio of main raw materials (3) after dilution is 1.5-2.5 for neutralizing agent.

[0010] Main raw material ratio of component B Polyether modified isocyanate Bayhydur 305 75-85 Propylene glycol methyl ether acetate 15-25 Dehumidifier Additive TI 0.1-3.0.

[0011] Description of the above ingredients: The aliphatic polycarbonate-modified waterborne polyurethane emulsion is from Jining Tangyi Company, the polyether-modified isocyanate is Bayhydur 305 from Covestro, the silicon-containing defoamer is Tego 810 from Digo Company, the ultra-high molecular weight dispersant is SV-295 from Jiaye Tiancheng Company, the titanium dioxide is R-706 from DuPont, the special modified nano-scale material is "quasi-spherical" nano-silica from Tenghe Chemical Company, the aqueous precipitated barium sulfate is produced by Qinba New Materials Company, and the multifunctional additive is AMP-95 produced by Enze Chemical Company, the defoamer is Tego901W from Digo Company, the wetting agent is Tego 270 from Digo Company, the wetting and leveling agent is BYK-3455 from BYK Chemical, the dehumidifier is Additive TI from Bayer Company, and the diethylene glycol butyl ether, dipropylene glycol butyl ether and propylene glycol methyl ether acetate are cosolvents in the system.

[0012] The present invention further discloses a method for preparing a water-based polyurethane topcoat with high construction performance, which is characterized by being carried out in the following steps: Preparation of component A: (1) Preparation of white water slurry Add deionized water to the stainless steel dispersion tank, adjust the speed of the high-speed disperser to 300-500 rpm, then add the silicon-containing defoamer Tego 810, ultra-high molecular weight dispersant SV-295 and multifunctional additive AMP-95 in turn, stir for 10 minutes, adjust the speed of the high-speed disperser to 1000-1200 rpm, add titanium dioxide R-706, special modified nano-grade materials and aqueous precipitated barium sulfate in turn, stir for 30 minutes to achieve uniform dispersion, and finally use a horizontal sand mill to control the fineness to less than 25μm, filter out for use; (2) Defoaming agent dilution treatment Add defoamer Tego 901W to the stainless steel dispersion tank, adjust the speed of the high-speed disperser to 300-500 rpm, add deionized water while stirring and disperse for 15 minutes, and then set aside; (3) Dilution of neutralizer Add deionized water to the stainless steel dispersion tank, adjust the speed of the high-speed disperser to a low speed of 300-500 rpm, add the multifunctional additive AMP-95 while stirring and disperse for 5-10 minutes, then set aside; (4) Blending: Add various raw materials in the following order Add aliphatic polycarbonate modified waterborne polyurethane emulsion into a stainless steel dispersion tank, adjust the speed of the high-speed disperser to 300-500 rpm, add the diluted neutralizer in step (3) to adjust the pH value of the system, disperse for 3-5 minutes, adjust the speed of the high-speed disperser to 500-800 rpm, add the white water slurry dispersed in the main raw material ratio (1) and disperse for 10-15 minutes, then add the diluted defoamer Tego 901W, wetting agent Tego 270 and wetting and leveling agent BYK 3455 in the main raw material ratio (2) in sequence under stirring, disperse for 3-5 minutes, then add deionized water, diethylene glycol butyl ether and dipropylene glycol butyl ether in sequence, disperse for 20 minutes, and use a filter to package after all indicators are tested and qualified.

[0013] Preparation of component B: Add polyether modified isocyanate Bayhydur 305 to a stainless steel dispersion tank, adjust the speed of the high-speed disperser to 800-1000 rpm, add propylene glycol methyl ether acetate and dehumidifier Additive TI in sequence under stirring, and disperse for 15 minutes before use.

[0014] The present invention uses aliphatic polycarbonate modified waterborne polyurethane emulsion and polyether modified isocyanate as main resins. The coating and the intermediate coating after the cross-linking reaction have excellent adhesion, and the large molecular weight can accelerate the curing rate of the coating; by adding special modified nano-grade materials, the white water slurry has an ideal anti-settling effect and can improve the covering power, strength, hardness and ultraviolet absorption ability of the coating; by adding ultra-high molecular weight dispersant SV-295, the special modified nano-grade materials and other pigments and fillers have excellent dispersibility and stability in the system; by adding Digo 810 defoamer, the white water slurry can be reduced in the grinding process The bubbles generated; the addition of wetting agent Digo 270 and wetting and leveling agent BYK-3455 greatly improves the substrate wetting effect and flowability of the coating, which helps to eliminate bubbles in the system; the addition of defoaming agent Digo 901W can use the degassing principle to eliminate bubbles that are difficult to remove in the system without damaging the adhesion between the coatings; the addition of multifunctional additive AMP-95 can significantly improve the pH value of the system, enhance storage stability, and has a good auxiliary wetting effect, which can reduce bubbles in the system and help improve the gloss and scrub resistance of the coating; the addition of dehumidifier Additive TI can remove moisture in the system and extend its storage period. The high-construction-performance polyurethane topcoat developed using the above-mentioned raw materials is a water-based product that meets the requirements of environmental protection policies; it has excellent inter-coat adhesion; it has good wetting effect and defoaming ability, and can be used for roller coating and spraying; it also has excellent mechanical properties, resistance to various liquid media and weather resistance; it has a fast drying rate, which can greatly save the time cost of construction; and it has the characteristics of light color, providing a basis for the colorization of the topcoat.

[0015] The present invention further discloses the application of water-based high-construction performance polyurethane topcoat on steel structure substrates by roller coating / spraying. Test results show that the product of the present invention has strong wetting ability, good defoaming effect and excellent flowability. The coating film can have a good appearance by roller coating or spraying on steel structures such as engineering machinery, and has excellent mechanical properties, wear resistance, resistance to various liquid media, scrub resistance and weather resistance.

[0016] The present invention is described in more detail as follows: The method for preparing the water-based high-construction performance polyurethane topcoat of the present invention comprises the following steps: Preparation of component A: (1) Preparation of white water slurry Add deionized water to the stainless steel dispersion tank, start with a low speed (300-500 rpm), then add the silicon-containing defoamer Tego 810 (adding the silicon-containing defoamer Tego 810 here can greatly reduce the generation of bubbles during the grinding process), ultra-high molecular weight dispersant SV-295 (the ultra-high molecular weight dispersant SV-295 selected for the test has excellent performance in color development, foam suppression, gloss and salt spray resistance) and multi-functional additive AMP-95 (adding the multi-functional additive AMP-95 here can adjust the system pH value to weak alkalinity and improve its storage stability, etc.), after dispersing for 10 minutes, use a higher speed (1000-1200 rpm), add titanium dioxide R-706, special modified nano-grade materials and aqueous precipitated barium sulfate in turn, disperse for 30 minutes (to achieve uniform dispersion of the powder, thereby shortening the grinding time), and finally use a horizontal sand mill to control the fineness below 25μm (generally 2-3 times of grinding are required), filter out and set aside.

[0017] (2) Defoaming agent dilution treatment Add defoamer Tego 901W to the stainless steel dispersion tank, run at a low speed (300-500 rpm), add deionized water while stirring and disperse for 15 minutes before use (the solid content of this defoamer is 100%, and the dilution treatment helps it to be evenly stirred in the system to achieve the best defoaming effect).

[0018] (3) Dilution of neutralizer Add deionized water to a stainless steel dispersion tank and run at a relatively low speed (300-500 rpm). Add the multifunctional additive AMP-95 while stirring and disperse for 5-10 minutes before use (the solid content of this multifunctional additive is over 90%. The dilution treatment helps to stir it evenly in the system. Direct use of the original solution will increase the viscosity of the system and cause the powder particles to agglomerate).

[0019] (4) Blending: Add various raw materials in the following order Add aliphatic polycarbonate modified waterborne polyurethane emulsion to a stainless steel dispersion tank, run at a relatively low speed (300-500 rpm), add the diluted neutralizer in step (3) to adjust the pH value of the system (adjust the pH value of the system to 8-9, add slowly to avoid too rapid increase in the viscosity of the system, which will cause the powder particles to agglomerate when the white water slurry is added later), disperse for 3-5 minutes, run at a medium speed (500-800 rpm), add the dispersed white water slurry of the main raw material ratio (1), disperse for 10-15 minutes, and add the diluted defoamer Tego 901W, wetting agent Tego 270, and wetting and leveling agent BYK of the main raw material ratio (2) in sequence under stirring. 3455 (the various additives added here are not stable foams and have almost no effect on the viscosity of the system. The addition of defoamers, wetting agents, and wetting and leveling agents here can make the product reach a balance between substrate wetting, coating leveling, and bubble elimination, thereby exerting the best effect). After dispersing for 3-5 minutes, add deionized water, diethylene glycol butyl ether, and dipropylene glycol butyl ether in turn (the addition of cosolvents helps to assist film formation, improve the drying rate and leveling of the coating, and extend the storage life of the system). Disperse for 20 minutes. After all indicators are tested and qualified, use a filter to package.

[0020] Preparation of component B: Add polyether modified isocyanate Bayhydur 305 to a stainless steel dispersing tank, run at medium to high speed (800-1000 rpm), add propylene glycol methyl ether acetate (to dilute the curing agent, facilitate dispersion during the construction mixing process, and maintain the best paint film quality) and dehumidifier Additive TI (to remove moisture from the system and enhance the storage stability of component B) in sequence under stirring, and disperse for 15 minutes before use.

[0021] Component A 90-100 B component 15-20 Main raw material ratio of component A (1) Preparation of white water slurry Deionized water 20.9 Silicone defoamer Tego 810 0.5 Ultra high molecular weight dispersant SV-295 8.0 Titanium dioxide R-706 27 Special modified nano-scale materials 32 Aqueous precipitated barium sulfate 11 Multifunctional additive AMP-95 0.6 (2) Dilution of defoaming agent Tego 901W 30 Deionized water 70 (3) Dilution of neutralizer Multifunctional additive AMP-95 10 Deionized water 90 (4) Harmony Aliphatic polycarbonate modified waterborne polyurethane emulsion 40-50 Deionized water 0-10 Main raw material ratio (2) Diluted defoamer Tego 901W 1.0-1.5 2-5-Diethylene glycol butyl ether 1-3 Dipropylene glycol butyl ether Wetting agent Tego 270 0.3-0.5 Wetting and leveling agent BYK 3455 0.1-0.3 Main raw material ratio (1) Dispersed white water slurry 40-50 The ratio of main raw materials (3) after dilution is 1.5-2.5 for neutralizing agent.

[0022] (2) Ratio of main raw materials of component B Polyether modified isocyanate Bayhydur 305 75-85 Propylene glycol methyl ether acetate 15-25 Dehumidifier Additive TI 0.1-3.0.

[0023] The present invention aims at the current trend of water-based steel structural parts such as engineering machinery, and the diversification of construction methods, so a reasonable combination of defoaming agent, wetting agent, wetting and leveling agent is adopted to realize the common use of roller coating and spray coating of topcoat, and the preparation of light-colored topcoat is the basis, which provides a good foundation for the colorization of topcoat; the selected aliphatic polycarbonate modified waterborne polyurethane emulsion has a solid content of 38%, which has excellent adhesion and a large molecular weight that can accelerate the curing rate of the coating; the selected polyether modified isocyanate has a solid content of 100%, which has good dispersibility, is easy to construct, and can improve the water resistance and aging resistance of the coating film; the selected special modified nano-scale material has an ultra-high amount of SiO2, and its effective component is more than 98%, and the microstructure The quasi-spherical shape greatly improves the mechanical strength, chemical resistance, wear resistance and aging resistance of the coating. The ultra-high molecular weight dispersant SV-295 selected has an anti-foaming structure, which can enhance the flow state of the system and has a super strong dispersing ability for pigments and fillers, thereby greatly enhancing the storage stability of the system. Deco 810 defoamer and Deco 901W defoamer are added to the system. The combination of these two silicon-containing defoamers can effectively solve the difficulty of defoaming water-based topcoat. Deco 810 defoamer has an excellent effect on eliminating bubbles during the grinding process. In the blending stage, it is compounded with Deco 901W defoamer with degassing effect to eliminate large bubbles and microbubbles in the system to a great extent. The wetting agent Tego Both 270 and BYK 3455, a wetting and leveling agent, contain silicone components, which can strongly reduce the surface tension of the system, enhance the substrate wetting effect and flowability of the coating, help eliminate bubbles in the system, improve adhesion, and achieve roller coating / spray coating without paint film defects; adding the multifunctional additive AMP-95 can effectively improve the pH value of the system to between 8 and 9, thereby extending the storage stability of the system. Its addition will have a certain impact on the viscosity of the system, so it needs to be diluted and added slowly before use to avoid excessive local viscosity and agglomeration of powder particles; adding the dehumidifier Additive TI can convert the water molecules in component B and greatly enhance the storage stability of the system; the co-solvent uses dipropylene glycol butyl ether, diethylene glycol butyl ether, and propylene glycol methyl ether acetate, which can be miscible with the deionized water in the system in any proportion to enhance the dissolution effect, help assist film formation, improve the drying rate and leveling effect of the coating, and extend the storage stability of the system.

[0024] Compared with the prior art, the water-based high-construction-performance polyurethane topcoat and its application disclosed in the present invention have the following positive effects: Aliphatic polycarbonate-modified waterborne polyurethane emulsion and polyether-modified isocyanate are selected as the main resins (the modified waterborne polyurethane emulsion and isocyanate curing agent both have the excellent properties of two or more resins, and the two rely on the reaction of -OH and -NCO to form a large molecular weight interpenetrating network structure, so that the prepared coating has higher density), which improves the mechanical properties of the coating, resistance to various liquid media, yellowing resistance and wear resistance; and because the molecular weight of the resin used is large, the reaction rate with the curing agent is accelerated, thereby greatly shortening the drying time of the coating and saving time costs for construction.

[0025] The use of ultra-high molecular weight dispersants prepared by block polymerization technology can utilize electrostatic repulsion and steric hindrance effects to achieve uniform and stable dispersion of micron- and nano-scale pigments and fillers, effectively preventing particle aggregation and sedimentation, and making the coating have good gloss, excellent color development, and excellent corrosion resistance.

[0026] The rational combination of ultra-high molecular weight dispersants with anti-foaming structures, silicon-containing defoamers and wetting and leveling agents can reduce bubbles during the production and use of coatings, enhance the flow state and stability of the coating film, and thus achieve the purpose of roller coating and spray coating.

[0027] The specially modified nano-scale material selected is a "quasi-spherical" nano-silica material with low roundness and high sphericity prepared by a unique particle shaping technology. After modification, its suspension, dispersibility and anti-sedimentation properties in the coating system are enhanced, thereby improving the coating's hardness, compressive strength, stability, scratch resistance, wear resistance, strong acid and alkali resistance, and aging resistance. DETAILED DESCRIPTION

[0028] The present invention is described below by specific embodiments. Unless otherwise specified, the technical means used in the present invention are methods known to those skilled in the art. In addition, the embodiments should be understood as illustrative rather than limiting the scope of the present invention, and the essence and scope of the present invention are limited only by the claims. For those skilled in the art, various changes or modifications to the material composition and dosage in these embodiments, without departing from the essence and scope of the present invention, also belong to the protection scope of the present invention.

[0029] The raw materials and reagents used in the present invention are all commercially available, among which the aliphatic polycarbonate modified waterborne polyurethane emulsion was purchased from Jining Tangyi Company, the polyether modified isocyanate Bayhydur 305 was purchased from Covestro, the silicon-containing defoamer Tego810 was purchased from Digo Company, the ultrahigh molecular weight dispersant SV-295 was purchased from Jiaye Tiancheng Company, the titanium dioxide R-706 was purchased from DuPont, the special modified nano-scale material was purchased from Tenghe Chemical Company, the aqueous precipitated barium sulfate was purchased from Qinba New Materials Company, the multifunctional additive AMP-95 was purchased from Enze Chemical Company, the defoamer Tego 901W was purchased from Digo Company, the wetting agent Tego 270 was purchased from Digo Company, the wetting and leveling agent BYK-3455 was purchased from BYK Chemical Company, and the dehumidifying agent Additive TI was purchased from Bayer, diethylene glycol butyl ether was purchased from Hengcheng Chemical Company, dipropylene glycol butyl ether was purchased from Hengcheng Chemical Company, and propylene glycol methyl ether acetate was purchased from Hengcheng Chemical Company.

[0030] Example 1 Water-based high-performance polyurethane topcoat Component A / Component B = 100 / 18 Main raw material ratio of component A: (1) Preparation of white water slurry Deionized water 20.9 Silicone defoamer Tego 810 0.5 Ultra high molecular weight dispersant SV-295 8.0 Titanium dioxide R-706 27 Special modified nano-scale materials 32 Aqueous precipitated barium sulfate 11 Multifunctional additive AMP-95 0.6 (2) Dilution of defoaming agent Tego 901W 30 Deionized water 70 (3) Dilution of neutralizer Multifunctional additive AMP-95 10 Deionized water 90 (4) Harmony Aliphatic polycarbonate modified waterborne polyurethane emulsion 44 Deionized water 1.0 Main raw material ratio (2) Diluted defoamer Tego 901W 1.0 Diethylene glycol butyl ether 3.0 Dipropylene glycol butyl ether 1.4 Wetting agent Tego 270 0.4 Wetting and leveling agent BYK 3455 0.2 Main raw material ratio (1) Dispersed white water slurry 47 Main raw material ratio (3) diluted neutralizer 2.0 Main raw material ratio of component B Polyether modified isocyanate Bayhydur 305 80 Propylene glycol methyl ether acetate 19.5 Dehumidifier Additive TI 0.5.

[0031] Example 2 Preparation method of water-based polyurethane topcoat with high construction performance Preparation of component A: (1) Preparation of white water slurry Add deionized water to the stainless steel dispersion tank, operate at a low speed (500 rpm), then add silicon-containing defoamer Tego 810, ultra-high molecular weight dispersant SV-295 and multifunctional additive AMP-95 in sequence. After dispersing for 10 minutes, operate at a higher speed (1200 rpm), add titanium dioxide R-706, special modified nano-grade materials and aqueous precipitated barium sulfate in sequence, disperse for 30 minutes, and finally grind with a horizontal sand mill for 3 times to control the fineness to below 25μm, filter out and set aside.

[0032] (2) Defoaming agent dilution treatment Add defoamer Tego 901W to the stainless steel dispersion tank, run at a low speed (500 rpm), add deionized water while stirring and disperse for 15 minutes before use.

[0033] (3) Dilution of neutralizer Add deionized water to the stainless steel dispersion tank, run at a low speed (500 rpm), add the multifunctional additive AMP-95 while stirring and disperse for 5-10 minutes before use.

[0034] (4) Blending: Add various raw materials in the following order Add aliphatic polycarbonate modified waterborne polyurethane emulsion into a stainless steel dispersion tank, operate at a relatively low speed (500 rpm), slowly add the diluted neutralizer in step (3) to adjust the pH value of the system to 8.5, disperse for 3-5 minutes, operate at a medium speed (800 rpm), add the dispersed white water slurry of main raw material ratio (1), disperse for 10-15 minutes, add the diluted defoamer Tego 901W, wetting agent Tego 270, wetting and leveling agent BYK 3455 of main raw material ratio (2) in sequence while stirring, disperse for 3-5 minutes, then add deionized water, diethylene glycol butyl ether, dipropylene glycol butyl ether in sequence, disperse for 20 minutes, use roller coating and spray coating processes to test product performance, and use a filter to package after all indicators are tested and qualified.

[0035] Preparation of component B: Add polyether modified isocyanate Bayhydur 305 to a stainless steel dispersion tank, run at a relatively high speed (1000 rpm), add propylene glycol methyl ether acetate and dehumidifier Additive TI in sequence while stirring, and disperse for 15 minutes before use.

[0036]

[0037]

[0038] Example 3 Comparison of viscosity, coating hardness and aging resistance of the special modified nano-scale material system added with different amounts of the present invention

[0039] The test results show that as the amount of special modified nano-scale materials added increases, the hardness and aging resistance of the coating gradually increase, but when the addition amount exceeds 15%, the performance decreases. Therefore, the optimal addition amount is 15%. This phenomenon occurs because the special modified nano-scale materials have a certain thixotropy in the system. As the addition amount increases, the viscosity of the system continues to increase. When the addition amount exceeds 15%, the viscosity of the system will be too large, causing the powder particles to agglomerate and disperse unevenly, which will further affect the performance of the coating.

[0040] Example 4

[0041] Conclusion: The water-based polyurethane topcoat with high construction performance of the present invention. This product meets the trend of water-based and has excellent adhesion to steel structural parts; the use of aliphatic polycarbonate-modified water-based polyurethane emulsion and polyether-modified isocyanate improves the drying rate, mechanical properties, chemical stability, and yellowing resistance of the paint film; by adding defoamers, wetting agents, and wetting and leveling agents to the formula, the wetting, defoaming, and leveling of the paint film are balanced, thereby achieving roller coating and spraying, and the coating film has good color development and high gloss; for the first time, special modified nano-scale materials are introduced into the water-based paint system, so that the paint film has excellent thixotropy, hardness, mechanical properties, wear resistance, aging resistance, and resistance to various liquid media. The prepared paint film is light in color, which has great cost advantages over similar products added with nano titanium dioxide and graphene materials.

Claims

1. A water-based high-performance polyurethane topcoat, characterized in that The topcoat is composed of the following raw materials in parts by weight: Component A 90-100 B component 15-20 Main raw material ratio of component A (1) Preparation of white water slurry Deionized water 20.9 Silicone defoamer Tego 810 0.5 Ultra high molecular weight dispersant SV-295 8.0 Titanium dioxide R-706 27 Special modified nano-scale materials 32 Aqueous precipitated barium sulfate 11 Multifunctional additive AMP-95 0.6 (2) Dilution of defoaming agent Tego 901W 30 Deionized water 70 (3) Dilution of neutralizer Multifunctional additive AMP-95 10 Deionized water 90 (4) Harmony Aliphatic polycarbonate modified waterborne polyurethane emulsion 40-50 Deionized water 0-10 Main raw material ratio (2) Diluted defoamer Tego 901W 1.0-1.5 2-5-Diethylene glycol butyl ether 1-3 Dipropylene glycol butyl ether Wetting agent Tego 270 0.3-0.5 Wetting and leveling agent BYK 3455 0.1-0.3 Main raw material ratio (1) Dispersed white water slurry 40-50 Main raw material ratio (3) diluted neutralizer 1.5-2.5; Main raw material ratio of component B Polyether modified isocyanate Bayhydur 305 75-85 Propylene glycol methyl ether acetate 15-25 Dehumidifier Additive TI 0.1-3.

0.

2. The method for preparing the water-based high-construction performance polyurethane topcoat according to claim 1, characterized in that Proceed as follows: Preparation of component A: (1) Preparation of white water slurry Add deionized water to the stainless steel dispersion tank, adjust the speed of the high-speed disperser to 300-500 rpm, then add the silicon-containing defoamer Tego 810, ultra-high molecular weight dispersant SV-295 and multifunctional additive AMP-95 in turn, stir for 10 minutes, adjust the speed of the high-speed disperser to 1000-1200 rpm, add titanium dioxide R-706, special modified nano-grade materials and aqueous precipitated barium sulfate in turn, stir for 30 minutes to achieve uniform dispersion, and finally use a horizontal sand mill to control the fineness to less than 25μm, filter out for use; (2) Defoaming agent dilution treatment Add defoamer Tego 901W to the stainless steel dispersion tank, adjust the speed of the high-speed disperser to 300-500 rpm, add deionized water while stirring and disperse for 15 minutes, and then set aside; (3) Dilution of neutralizer Add deionized water to the stainless steel dispersion tank, adjust the speed of the high-speed disperser to a low speed of 300-500 rpm, add the multifunctional additive AMP-95 while stirring and disperse for 5-10 minutes, then set aside; (4) Blending: Add various raw materials in the following order Add aliphatic polycarbonate modified waterborne polyurethane emulsion into a stainless steel dispersion tank, adjust the speed of the high-speed disperser to 300-500 rpm, add the diluted neutralizer in step (3) to adjust the pH value of the system, and adjust the speed of the high-speed disperser to 500-800 rpm after dispersion for 3-5 minutes. Add the white water slurry dispersed in the main raw material ratio (1) and disperse for 10-15 minutes. Then, add the diluted defoamer Tego 901W, wetting agent Tego 270, and wetting and leveling agent BYK 3455 in the main raw material ratio (2) in sequence under stirring. After dispersion for 3-5 minutes, add deionized water, diethylene glycol butyl ether, and dipropylene glycol butyl ether in sequence. Disperse for 20 minutes. After all indicators are tested and qualified, use a filter to package. Preparation of component B: Add polyether modified isocyanate Bayhydur 305 to a stainless steel dispersion tank, adjust the speed of the high-speed disperser to 800-1000 rpm, add propylene glycol methyl ether acetate and dehumidifier Additive TI in sequence under stirring, disperse for 15 minutes and set aside.

3. Application of the water-based high-construction-performance polyurethane topcoat according to claim 1 for roller coating / spraying on construction machinery.

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