High-film-thickness and high-weather-resistance polyurethane coating on surface of automobile ornament as well as preparation method and application thereof

Abstract

The invention discloses a high-film-thickness and high-weather-resistance polyurethane coating for the surface of an automobile ornament, a preparation method and application, and relates to the technical field of industrial coatings, the high-film-thickness and high-weather-resistance polyurethane coating comprises the following specific components: a primer and a finishing coat; the primer comprises a nano material, a movable wetting agent with a fluorine modified group, resin, an alcohol solvent and a filler; the finish paint comprises a composite resin system, an ultraviolet light absorber, a light stabilizer, a nano reinforced phase, a thixotropic system, a silane coupling agent, a base material wetting agent and a curing agent. According to the polyurethane coating, the preparation method and the application, the nano material is introduced into the primer, so that a compact protective layer is formed. The nano reinforced phase is added into the finish paint, so that the chemical resistance and aging resistance of the coating are greatly enhanced. In addition, a primer and finish paint spraying process is adopted, a high-film-thickness coating of 1000-2000 microns can be achieved, meanwhile, ultrahigh leveling property and fullness are kept, the construction process is effectively optimized, the appearance effect is improved, the construction efficiency is remarkably improved, and the construction period is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial coatings, in particular to a high-thickness and high-weather-resistant polyurethane coating for the surface of automobile accessories, a preparation method and an application thereof. Background Art

[0002] In the automotive trim coating field, high-build polyurethane coatings are widely used for both protective and aesthetic treatments of vehicle exterior trims due to their excellent mechanical properties, chemical resistance, and decorative effects. However, existing high-build polyurethane coatings on the market still have many shortcomings during application.

[0003] First, the construction process is complex. Existing coatings typically require rigorous surface preparation, including degreasing, rust removal, and polishing, to ensure adhesion. Furthermore, achieving the desired film thickness typically requires multiple application steps, including primer, midcoat, and topcoat. Each step requires a certain amount of drying and curing time, resulting in a long construction cycle and impacting production efficiency.

[0004] Secondly, weather resistance is limited. Although polyurethane coatings have a certain degree of weather resistance, long-term exposure to ultraviolet rays, high temperatures, and humid environments, especially when high film thickness is used, can easily lead to aging phenomena such as gloss loss, chalking, and yellowing, which affect the coating's appearance and long-term protective performance. This is particularly noticeable in areas with strong ultraviolet radiation or in extreme environments. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention provides a high-thickness and highly weather-resistant polyurethane coating for the surface of automotive accessories, a preparation method and an application thereof, to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions: The embodiment of the present invention provides a high-thickness and high-weather-resistant polyurethane coating for the surface of automobile accessories, comprising the following specific components: a primer and a topcoat; The primer comprises nanomaterials, an active wetting agent with fluorine-modified groups, a resin, an alcohol solvent, and a filler; The topcoat comprises component A and component B, wherein: Component A includes a composite resin system, a UV absorber, a light stabilizer, a nano-reinforcement phase, a thixotropic system, a silane coupling agent, and a substrate wetting agent; Component B includes the curing agent.

[0007] To further optimize this technical solution, the primer comprises the following parts by mass: Nanomaterials are 25-30 parts; The active wetting agent with fluorine-modified group is 5-10 parts; Resin is 40-50 parts; Alcohol solvent is 15-50 parts; The filler is 5-10 parts.

[0008] To further optimize this technical solution, in the primer: The nanomaterial is carbon nanotube or graphene; the carbon nanotube is selected from multi-walled carbon nanotube to enhance the conductivity and corrosion resistance of the primer; Active wetting agents with fluorine-modified groups include fluorinated alkylsilanes and fluorinated surfactants. The fluorinated alkylsilane is 3-fluoropropyltriethoxysilane, which is used as a wetting agent and penetrant to improve the contact between the primer and the substrate and enhance the permeability. The fluorinated surfactant is a polyfluoroolefin PFPE surfactant, which is used to increase the wettability and filling properties of the coating. The resin is polyurethane resin or epoxy resin; polyurethane resin is polytetrafluoroethylene modified polyurethane resin to provide the adhesion of the primer; epoxy resin is bisphenol A type epoxy resin to provide adhesion and corrosion resistance; Alcohol solvents such as isopropyl alcohol or xylene are used to adjust the fluidity of the primer and help it be evenly distributed on the surface of the substrate; Fillers are titanium dioxide or talcum powder; titanium dioxide is used to increase the hiding power and weather resistance of the primer; talcum powder is used to enhance the mechanical strength and physical properties of the primer.

[0009] To further optimize this technical solution, the topcoat comprises the following parts by mass: The composite resin system is 85-89 parts; 1.5-2.0 parts of ultraviolet absorber; Light stabilizer is 0.8-1.2 parts; The nano-reinforced phase is 1.8-3.7 parts; Thixotropic system is 1.0-2.2 parts; Silane coupling agent is 1.8-2.2 parts; The substrate wetting agent is 0.3-0.5 parts; The curing agent is 20-24 parts.

[0010] Further optimizing this technical solution, in the topcoat: The composite resin system includes star-shaped acrylic polyol and modified hydrogenated epoxy resin; UV absorbers include benzotriazole and triazine UV absorbers; Light stabilizers include high molecular weight and low molecular weight hindered amine light stabilizers; The nano-reinforced phase includes fumed hydrophobic nano-silica and flaky mica powder; Thixotropic systems include polyamide wax, modified urea, and organic bentonite; The curing agent is a mixed curing agent of HDI trimer and IPDI biuret.

[0011] Further optimizing the technical solution, the star-shaped acrylic polyol and the modified hydrogenated epoxy resin are compounded in a ratio of 3:1 to ensure that the viscosity is less than 1500 cP at 25±1°C when the solid content reaches 78%; Benzotriazole and triazine UV absorbers are mixed in a ratio of 2:1; The MW of high molecular weight hindered amine light stabilizer is greater than 2000, and the MW of low molecular weight hindered amine light stabilizer is 500-800; and they are combined in a gradient ratio of 3:2; The mass fraction of fumed hydrophobic nano-silica is 0.3-0.7 parts; the mass fraction of flaky mica powder is 1.5-3.0 parts; The mass fraction of polyamide wax is 0.5-1.0 parts; the mass fraction of modified urea is 0.2-0.5 parts; the mass fraction of organic bentonite is 0.3-0.7 parts; HDI trimer and IPDI biuret mixed curing agent were mixed in a ratio of 4:1, and the NCO content was 18.5±0.3%.

[0012] A method for preparing a high-thickness, high-weather-resistant polyurethane coating for the surface of an automobile trim is prepared based on the above-mentioned high-thickness, high-weather-resistant polyurethane coating for the surface of an automobile trim, comprising preparing a primer: Mixing the resin with an alcohol solvent; Add a fluorine-modified group active wetting agent to the resin and continue stirring until the resin is uniform and stable; The nanomaterials are uniformly dispersed into the resin by ultrasonic dispersion or high shear stirring; Add filler, fully disperse the filler through mechanical stirring or sand grinding, and mix it evenly with the resin and other ingredients to form a primer system; The mixed primer system is sealed and matured.

[0013] To further optimize this technical solution, the preparation method further includes preparing the topcoat: The composite resin system was mixed using a high shear mixing device, and a sand mill was used with a line speed controlled at 12 m / s to achieve a D50 particle size of ≤15 μm; Introducing UV absorbers and light stabilizers, and adding nano-reinforcement phases; Add thixotropic system and stir thoroughly using high shear mixing or three-roll milling; Add silane coupling agent and substrate wetting agent, and mix them thoroughly with other components by stirring to promote the combination of topcoat and primer; Add curing agent to carry out curing reaction, prompting the topcoat to undergo cross-linking reaction to form a hard coating; Finally, carry out closed aging at 25°C for 24 hours to ensure that the viscosity change rate of the topcoat is less than 5%.

[0014] An application of a high-film-thickness, high-weather-resistant polyurethane coating on the surface of an automobile trim is based on the application of the above-mentioned high-film-thickness, high-weather-resistant polyurethane coating on the surface of an automobile trim, including the application of a primer: Treat the surface of the substrate and apply the primer evenly on the surface of the substrate by spraying, brushing or dipping. When spraying, keep the nozzle about 5-20cm away from the surface of the substrate and the spraying angle perpendicular to the surface. Place the substrate coated with primer in an environment of 25°C for natural drying or use a drying process for 30-60 minutes until the primer surface is completely dry.

[0015] Further optimizing this technical solution, the application also includes applying the topcoat: Apply the topcoat on the dried primer by spraying. When spraying, keep the nozzle 15-20cm away from the primer surface and spray at a uniform speed to continuously add coating thickness to reach a super thick film thickness of 1000-2000μm. After coating, place the coating in a dry environment at 25-30°C for 60-90 minutes to ensure that the topcoat layer is completely dry; Use ultraviolet lamps to cure the topcoat with ultraviolet radiation, and the irradiation time is controlled within 10-20 minutes to complete the application of polyurethane coating.

[0016] Compared with the prior art, the present invention provides a high-thickness and high-weather-resistant polyurethane coating for the surface of automotive accessories, a preparation method, and an application thereof, which have the following beneficial effects: This high-thickness, highly weather-resistant polyurethane coating for automotive trim surfaces, its preparation method, and its application, incorporate nanomaterials into the primer to form a dense protective layer, effectively enhancing the coating's adhesion to the substrate and improving interlayer bonding. Furthermore, the addition of a nano-reinforcement phase to the topcoat significantly enhances the coating's chemical and aging resistance, ensuring long-term use without loss of gloss, chalking, or yellowing. Furthermore, the primer + topcoat spraying process achieves high film thicknesses of 1000-2000μm while maintaining exceptional leveling and fullness. This effectively optimizes the construction process, enhances the appearance, significantly improves construction efficiency, and shortens the construction cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a schematic diagram of the composition of a high-thickness and highly weather-resistant polyurethane coating for the surface of automotive accessories proposed by the present invention; Figure 2 This is a schematic flow chart of a method for preparing a high-thickness and highly weather-resistant polyurethane coating for the surface of automotive accessories proposed by the present invention; Figure 3 This is a schematic diagram of the application process of a high-thickness and high-weather-resistant polyurethane coating on the surface of automotive accessories proposed by the present invention; Figure 4 This is a schematic diagram of a product of a high-thickness and highly weather-resistant polyurethane coating for the surface of automotive accessories proposed by the present invention; Figure 5 This is a schematic diagram of the second product of the high-thickness and highly weather-resistant polyurethane coating for the surface of automotive accessories proposed by the present invention. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0020] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it constitute a separate or selective embodiment that is mutually exclusive with other embodiments.

[0022] Example 1: Reference Figure 1 , which is the first embodiment of the present invention, provides a high-thickness and high-weather-resistant polyurethane coating for the surface of automobile accessories, including the following specific components: a primer and a topcoat; The primer comprises nanomaterials, an active wetting agent with fluorine-modified groups, resin, an alcohol solvent, and a filler. The primer can form a dense protective layer, effectively protect the substrate, and solve the interlayer adhesion between the coating and the substrate to a certain extent.

[0023] In the primer, according to the following mass parts: Nanomaterials are 25-30 parts; The active wetting agent with fluorine-modified group is 5-10 parts; Resin is 40-50 parts; Alcohol solvent is 15-50 parts; The filler is 5-10 parts.

[0024] In this embodiment, The nanomaterial is carbon nanotube or graphene; the carbon nanotube uses multi-walled carbon nanotube to enhance the conductivity and corrosion resistance of the primer.

[0025] Active wetting agents with fluorinated groups include fluorinated alkylsilanes and fluorinated surfactants. The fluorinated alkylsilane is 3-fluoropropyltriethoxysilane, which acts as a wetting agent and penetrant, improving the contact between the primer and the substrate and enhancing permeability. The fluorinated surfactant is a polyfluoroolefin (PFPE) surfactant, which increases the coating's wettability and filling properties, ensuring the primer penetrates deep into the substrate's micropores to form a stable protective structure.

[0026] The resin is polyurethane resin or epoxy resin; the polyurethane resin is polytetrafluoroethylene modified polyurethane resin to provide the adhesion of the primer; the epoxy resin is bisphenol A type epoxy resin to provide adhesion and corrosion resistance.

[0027] Alcohol solvents such as isopropyl alcohol or xylene are used to adjust the fluidity of the primer and help the primer be evenly distributed on the surface of the substrate.

[0028] Fillers are titanium dioxide or talcum powder; titanium dioxide is used to increase the hiding power and weather resistance of the primer; talcum powder is used to enhance the mechanical strength and physical properties of the primer.

[0029] The topcoat comprises component A and component B, wherein: Component A includes a composite resin system, an ultraviolet absorber, a light stabilizer, a nano-reinforcement phase, a thixotropic system, a silane coupling agent, and a substrate wetting agent.

[0030] Component B includes the curing agent.

[0031] In the topcoat, according to the following mass parts: The composite resin system is 85-89 parts; 1.5-2.0 parts of ultraviolet absorber; Light stabilizer is 0.8-1.2 parts; The nano-reinforced phase is 1.8-3.7 parts; Thixotropic system is 1.0-2.2 parts; Silane coupling agent is 1.8-2.2 parts; The substrate wetting agent is 0.3-0.5 parts; The curing agent is 20-24 parts.

[0032] In this embodiment, the composite resin system includes a star-shaped acrylic polyol and a modified hydrogenated epoxy resin with a hydroxyl value of 110-130 mg KOH / g; the star-shaped acrylic polyol and the modified hydrogenated epoxy resin are compounded in a ratio of 3:1 to ensure that the viscosity is less than 1500 cP when the solid content reaches 78% at 25±1°C.

[0033] The ultraviolet absorbers include benzotriazole and triazine ultraviolet absorbers; the benzotriazole and triazine ultraviolet absorbers are compounded in a ratio of 2:1.

[0034] Light stabilizers include high-molecular-weight and low-molecular-weight hindered amine light stabilizers; high-molecular-weight hindered amine light stabilizers have a MW > 2000, while low-molecular-weight hindered amine light stabilizers have a MW = 500-800. A 3:2 gradient combination ensures the stability of the coating during long-term use.

[0035] The nano-reinforcement phase consists of fumed hydrophobic nano-silica and flaky mica powder (aspect ratio > 50). The fumed hydrophobic nano-silica is present in an amount of 0.3-0.7 parts by weight, while the flaky mica powder is present in an amount of 1.5-3.0 parts by weight. The nano-silica enhances the coating's wear and scratch resistance, while the flaky mica powder effectively improves the coating's hardness and gloss.

[0036] The thixotropic system comprises polyamide wax, modified urea and organic bentonite; the mass proportion of the polyamide wax is 0.5-1.0 part; the mass proportion of the modified urea is 0.2-0.5 part; and the mass proportion of the organic bentonite is 0.3-0.7 part.

[0037] Substrate wetting agent to ensure even coating coverage.

[0038] The curing agent is a mixture of HDI trimer and IPDI biuret, mixed in a 4:1 ratio with an NCO content of 18.5 ± 0.3%. This provides excellent hardening and ensures high weather and chemical resistance of the topcoat.

[0039] The topcoat improves its chemical resistance and aging resistance by adding high-performance materials such as the above-mentioned nano-silica.

[0040] Example 2: Reference Figure 2 , which is the second embodiment of the present invention, provides a method for preparing a high-thickness, high-weather-resistant polyurethane coating for the surface of an automobile accessory. The method is based on the high-thickness, high-weather-resistant polyurethane coating for the surface of an automobile accessory described in the first embodiment, and includes preparing a primer: Mixing the resin with an alcohol solvent; Add a fluorine-modified group active wetting agent to the resin and continue stirring until the resin is uniform and stable; The nanomaterials are uniformly dispersed into the resin by ultrasonic dispersion or high shear stirring; Add filler, fully disperse the filler through mechanical stirring or sand grinding, and mix it evenly with the resin and other ingredients to form a primer system; The mixed primer system is sealed and matured.

[0041] The preparation method further comprises preparing the topcoat: The composite resin system was mixed using a high shear mixing device, and a sand mill was used with a line speed controlled at 12 m / s to achieve a D50 particle size of ≤15 μm; Introducing UV absorbers and light stabilizers, and adding nano-reinforcement phases; Add thixotropic system and stir thoroughly using high shear mixing or three-roll milling; Add silane coupling agent and substrate wetting agent, and mix them thoroughly with other components by stirring to promote the combination of topcoat and primer; Add curing agent to carry out curing reaction, prompting the topcoat to undergo cross-linking reaction to form a hard coating; Finally, carry out closed aging at 25°C for 24 hours to ensure that the viscosity change rate of the topcoat is less than 5%.

[0042] Example 3: Reference Figure 3-5 , which is the third embodiment of the present invention, provides an application of a high-thickness, high-weather-resistant polyurethane coating on the surface of an automobile accessory. The application of the high-thickness, high-weather-resistant polyurethane coating on the surface of an automobile accessory described in the first embodiment includes applying the following to the primer: Treat the surface of the substrate and apply the primer evenly on the surface of the substrate by spraying, brushing or dipping. When spraying, keep the nozzle about 5-20cm away from the surface of the substrate and the spraying angle perpendicular to the surface. Place the substrate coated with primer in an environment of 25°C for natural drying or use a drying process for 30-60 minutes until the primer surface is completely dry.

[0043] The application also includes the application of a topcoat: Apply the topcoat on the dried primer by spraying. When spraying, keep the nozzle 15-20cm away from the primer surface and spray at a uniform speed to continuously add coating thickness to reach a super thick film thickness of 1000-2000μm. After coating, place the coating in a dry environment at 25-30°C for 60-90 minutes to ensure that the topcoat layer is completely dry; Use ultraviolet lamp to cure the topcoat with ultraviolet radiation, and control the irradiation time to 10-20 minutes to complete the application of polyurethane coating. Figure 4 and Figure 5 Application products shown.

[0044] The above-mentioned process of primer + topcoat and wet-to-wet spraying is adopted, so that the coating film thickness can be continuously superimposed, so the film thickness can reach a high film thickness of 1000-2000μm, and the coating has ultra-high leveling and ultra-high fullness, which greatly optimizes the original complex construction process, greatly improves the appearance effect, greatly improves the construction efficiency and shortens the construction period.

[0045] At the same time, the test items shown in Table 1 are used to perform product performance tests.

[0046] Table 1 Performance test Example 4: To adapt to different application environments and requirements, this embodiment proposes the following design solutions that can be modified: Implementation 1: Primer: Using nanotechnology, combined with active wetting agents and penetrants with special fluorine-modified groups, it achieves close bonding with the substrate and forms a dense protective layer.

[0047] Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, etc. to improve the hardness, scratch resistance, chemical resistance, aging resistance, etc. of the topcoat.

[0048] The wet-on-wet spraying method can achieve an unconventional ultra-high film thickness of 800-1000μm.

[0049] Implementation 2: Primer: Using nanotechnology, combined with active wetting agents and penetrants with special fluorine-modified groups, it achieves close bonding with the substrate and forms a dense protective layer.

[0050] Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, etc. to improve the hardness, scratch resistance, chemical resistance, aging resistance, etc. of the topcoat.

[0051] The wet-on-wet spraying method is used, so that the film thickness can be continuously superimposed to achieve an unconventional ultra-high film thickness of 1000-1200μm.

[0052] Implementation 3: Primer: Using nanotechnology, combined with active wetting agents and penetrants with special fluorine-modified groups, it achieves close bonding with the substrate and forms a dense protective layer.

[0053] Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, etc. to improve the hardness, scratch resistance, chemical resistance, aging resistance, etc. of the topcoat.

[0054] The wet-on-wet spraying method is used, so that the film thickness can be continuously added up to achieve an unconventional ultra-high film thickness of 1200-1400μm.

[0055] Implementation 4: Primer: Using nanotechnology, combined with active wetting agents and penetrants with special fluorine-modified groups, it achieves close bonding with the substrate and forms a dense protective layer.

[0056] Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, etc. to improve the hardness, scratch resistance, chemical resistance, aging resistance, etc. of the topcoat.

[0057] The wet-on-wet spraying method is used, so that the film thickness can be continuously added up to achieve an unconventional ultra-high film thickness of 1400-1600μm.

[0058] Implementation 5: Primer: Using nanotechnology, combined with active wetting agents and penetrants with special fluorine-modified groups, it achieves close bonding with the substrate and forms a dense protective layer.

[0059] Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, etc. to improve the hardness, scratch resistance, chemical resistance, aging resistance, etc. of the topcoat.

[0060] The wet-on-wet spraying method is used, so that the film thickness can be continuously added up to achieve an unconventional ultra-high film thickness of 1600-1800μm.

[0061] Implementation 6: Primer: Using nanotechnology, combined with active wetting agents and penetrants with special fluorine-modified groups, it achieves close bonding with the substrate and forms a dense protective layer.

[0062] Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, etc. to improve the hardness, scratch resistance, chemical resistance, aging resistance, etc. of the topcoat.

[0063] The wet-on-wet spraying method is used, so that the film thickness can be continuously superimposed to achieve an unconventional ultra-high film thickness of 1800-2000μm.

[0064] Implementation Plan 7: Primer: Using nanotechnology, combined with active wetting agents and penetrants with special fluorine-modified groups, it achieves close bonding with the substrate and forms a dense protective layer.

[0065] Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, etc. to improve the hardness, scratch resistance, chemical resistance, aging resistance, etc. of the topcoat.

[0066] The wet-on-wet spraying method is used, so that the film thickness can be continuously added up to achieve an unconventional ultra-high film thickness of 2000-2200μm.

[0067] In the following schemes, the topcoat is sprayed directly, including: Implementation Plan 8: Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, benzotriazoles and triazines to improve the hardness, scratch resistance, chemical resistance, leveling, fullness and aging resistance of the topcoat.

[0068] The wet-on-wet spraying method can achieve an unconventional ultra-high film thickness of 800-1000μm.

[0069] Implementation 9: Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, benzotriazoles and triazines to improve the hardness, scratch resistance, chemical resistance, leveling, fullness and aging resistance of the topcoat.

[0070] The wet-on-wet spraying method is used, so that the film thickness can be continuously superimposed to achieve an unconventional ultra-high film thickness of 1000-1200μm.

[0071] Implementation Plan 10: Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, benzotriazoles and triazines to improve the hardness, scratch resistance, chemical resistance, leveling, fullness and aging resistance of the topcoat.

[0072] The wet-on-wet spraying method is used, so that the film thickness can be continuously added up to achieve an unconventional ultra-high film thickness of 1200-1400μm.

[0073] Implementation Plan 11: Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, benzotriazoles and triazines to improve the hardness, scratch resistance, chemical resistance, leveling, fullness and aging resistance of the topcoat.

[0074] The wet-on-wet spraying method is used, so that the film thickness can be continuously added up to achieve an unconventional ultra-high film thickness of 1400-1600μm.

[0075] Implementation Plan 12: Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, benzotriazoles and triazines to improve the hardness, scratch resistance, chemical resistance, leveling, fullness and aging resistance of the topcoat.

[0076] The wet-on-wet spraying method is used, so that the film thickness can be continuously added up to achieve an unconventional ultra-high film thickness of 1600-1800μm.

[0077] Implementation Plan 13: Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, benzotriazoles and triazines to improve the hardness, scratch resistance, chemical resistance, leveling, fullness and aging resistance of the topcoat.

[0078] The wet-on-wet spraying method is used, so that the film thickness can be continuously superimposed to achieve an unconventional ultra-high film thickness of 1800-2000μm.

[0079] Implementation Plan 14: Topcoat: Add high-performance materials such as nano-alumina, nano-silica, titanium dioxide, cerium oxide, nano-montmorillonite, benzotriazoles and triazines to improve the hardness, scratch resistance, chemical resistance, leveling, fullness and aging resistance of the topcoat.

[0080] The wet-on-wet spraying method is used, so that the film thickness can be continuously added up to achieve an unconventional ultra-high film thickness of 2000-2200μm.

[0081] At the same time, in order to adapt to different application environments and requirements, this embodiment proposes the following possible design changes: Primer material optimization: Introduce different types of nanomaterials (such as carbon nanotubes, graphene, etc.) to enhance the conductivity and corrosion resistance of the primer and adapt it to special industrial environments.

[0082] Enhanced topcoat functionality: According to the needs of specific application scenarios (such as outdoor, indoor, special environments, etc.), UV blockers, UV absorbers, mildew inhibitors, self-cleaning coatings, etc. are added to enhance the functionality of the topcoat.

[0083] Intelligent application: Integrated intelligent monitoring system to monitor the status of the coating layer (such as humidity, temperature, wear degree, etc.) in real time, provide remote data support, and optimize maintenance strategies.

[0084] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A high-thickness and high-weather-resistant polyurethane coating for the surface of automotive accessories, characterized in that: It includes the following specific components: primer and topcoat; The primer comprises nanomaterials, an active wetting agent with fluorine-modified groups, a resin, an alcohol solvent, and a filler; The topcoat comprises component A and component B, wherein: Component A includes a composite resin system, a UV absorber, a light stabilizer, a nano-reinforcement phase, a thixotropic system, a silane coupling agent, and a substrate wetting agent; Component B includes the curing agent.

2. The high-thickness and high-weather-resistant polyurethane coating for automobile accessories according to claim 1, characterized in that: In the primer, according to the following mass parts: Nanomaterials are 25-30 parts; The active wetting agent with fluorine-modified group is 5-10 parts; Resin is 40-50 parts; Alcohol solvent is 15-50 parts; The filler is 5-10 parts.

3. The high-thickness and high-weather-resistant polyurethane coating for automobile accessories according to claim 1, characterized in that: In the primer: The nanomaterial is carbon nanotube or graphene; the carbon nanotube is selected from multi-walled carbon nanotube to enhance the conductivity and corrosion resistance of the primer; Active wetting agents with fluorine-modified groups include fluorinated alkylsilanes and fluorinated surfactants. The fluorinated alkylsilane is 3-fluoropropyltriethoxysilane, which is used as a wetting agent and penetrant to improve the contact between the primer and the substrate and enhance the permeability. The fluorinated surfactant is a polyfluoroolefin PFPE surfactant, which is used to increase the wettability and filling properties of the coating. The resin is polyurethane resin or epoxy resin; the polyurethane resin is polytetrafluoroethylene modified polyurethane resin to provide the adhesion of the primer; Epoxy resin uses bisphenol A epoxy resin to provide adhesion and corrosion resistance; Alcohol solvents such as isopropyl alcohol or xylene are used to adjust the fluidity of the primer and help it be evenly distributed on the surface of the substrate; Fillers are titanium dioxide or talcum powder; titanium dioxide is used to increase the hiding power and weather resistance of the primer; talcum powder is used to enhance the mechanical strength and physical properties of the primer.

4. The high-thickness and high-weather-resistant polyurethane coating for automobile accessories according to claim 1, characterized in that: In the topcoat, according to the following mass parts: The composite resin system is 85-89 parts; 1.5-2.0 parts of ultraviolet absorber; Light stabilizer is 0.8-1.2 parts; The nano-reinforced phase is 1.8-3.7 parts; Thixotropic system is 1.0-2.2 parts; Silane coupling agent is 1.8-2.2 parts; The substrate wetting agent is 0.3-0.5 parts; The curing agent is 20-24 parts.

5. The high-thickness and high-weather-resistant polyurethane coating for automobile accessories according to claim 1, characterized in that: In the topcoat: The composite resin system includes star-shaped acrylic polyol and modified hydrogenated epoxy resin; UV absorbers include benzotriazole and triazine UV absorbers; Light stabilizers include high molecular weight and low molecular weight hindered amine light stabilizers; The nano-reinforced phase includes fumed hydrophobic nano-silica and flaky mica powder; Thixotropic systems include polyamide wax, modified urea, and organic bentonite; The curing agent is a mixed curing agent of HDI trimer and IPDI biuret.

6. The high-thickness and high-weather-resistant polyurethane coating for automobile accessories according to claim 5, characterized in that: The star-shaped acrylic polyol and the modified hydrogenated epoxy resin are compounded in a ratio of 3:1 to ensure that the viscosity is less than 1500 cP at 25±1°C when the solid content reaches 78%; Benzotriazole and triazine UV absorbers are mixed in a ratio of 2:1; The MW of the high molecular weight hindered amine light stabilizer is greater than 2000, and the MW of the low molecular weight hindered amine light stabilizer is 500-800; and the combination is in a gradient of 3:2; The mass fraction of fumed hydrophobic nano-silica is 0.3-0.7 parts; the mass fraction of flaky mica powder is 1.5-3.0 parts; The mass fraction of polyamide wax is 0.5-1.0 parts; the mass fraction of modified urea is 0.2-0.5 parts; the mass fraction of organic bentonite is 0.3-0.7 parts; HDI trimer and IPDI biuret mixed curing agent were mixed in a ratio of 4:1, and the NCO content was 18.5±0.3%.

7. A method for preparing a high-thickness, high-weather-resistant polyurethane coating for automobile accessories, the method comprising preparing the high-thickness, high-weather-resistant polyurethane coating for automobile accessories according to any one of claims 1 to 6, wherein: Including the preparation of primer: Mixing the resin with an alcohol solvent; Add a fluorine-modified group active wetting agent to the resin and continue stirring until the resin is uniform and stable; The nanomaterials are uniformly dispersed into the resin by ultrasonic dispersion or high shear stirring; Add filler, fully disperse the filler through mechanical stirring or sand grinding, and mix it evenly with the resin and other ingredients to form a primer system; The mixed primer system is sealed and matured.

8. The method for preparing a high-thickness and high-weather-resistant polyurethane coating for automobile accessories according to claim 7, characterized in that: The preparation method further comprises preparing the topcoat: The composite resin system was mixed using a high shear mixing device, and a sand mill was used with a line speed controlled at 12 m / s to achieve a D50 particle size of ≤15 μm; Introducing UV absorbers and light stabilizers, and adding nano-reinforcement phases; Add thixotropic system and stir thoroughly using high shear mixing or three-roll milling; Add silane coupling agent and substrate wetting agent, and mix them thoroughly with other components by stirring to promote the combination of topcoat and primer; Add curing agent to carry out curing reaction, prompting the topcoat to undergo cross-linking reaction to form a hard coating; Finally, carry out closed aging at 25°C for 24 hours to ensure that the viscosity change rate of the topcoat is less than 5%.

9. An application of a high-thickness, high-weather-resistant polyurethane coating on the surface of an automobile accessory, based on the application of the high-thickness, high-weather-resistant polyurethane coating on the surface of an automobile accessory according to any one of claims 1 to 6, characterized in that: Includes application of primer: Treat the surface of the substrate and apply the primer evenly on the surface of the substrate by spraying, brushing or dipping. When spraying, keep the nozzle about 5-20cm away from the surface of the substrate and the spraying angle perpendicular to the surface. Place the substrate coated with primer in an environment of 25°C for natural drying or use a drying process for 30-60 minutes until the primer surface is completely dry.

10. The use of a high-thickness and high-weather-resistant polyurethane coating on the surface of automobile accessories according to claim 9, characterized in that: The application also includes the application of a topcoat: Apply the topcoat on the dried primer by spraying. When spraying, keep the nozzle 15-20cm away from the primer surface and spray at a uniform speed to continuously add coating thickness to reach a super thick film thickness of 1000-2000μm. After coating, place the coating in a dry environment at 25-30°C for 60-90 minutes to ensure that the topcoat layer is completely dry; Use ultraviolet lamps to cure the topcoat with ultraviolet radiation, and the irradiation time is controlled within 10-20 minutes to complete the application of polyurethane coating.

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