High-weatherability multi-color coating and preparation method thereof

Abstract

The application belongs to the technical field of paint, and particularly relates to a high-weather-resistance multi-color paint and a preparation method thereof. The paint comprises the following components in parts by weight: 80-100 parts of organic silicon polyurethane, 10-15 parts of boron nitride nanosheet, 4-8 parts of nano-silica particles, 2-5 parts of polyurethane fluff micro powder, 1-8 parts of auxiliary agent, and 100-500 parts of solvent. The organic silicon polyurethane is used as the main film-forming resin, and the ternary components of the boron nitride nanosheet layer barrier, the small-particle-size nano-silica particles for constructing the micro-nano hydrophobic structure, and the polyurethane fluff micro powder for assisting in optimizing the film structure are used. The morphology and size effects among the two-dimensional boron nitride nanosheet, the spherical nano-silica particles, and the polyurethane fluff micro powder are utilized, so that the technical problems of the traditional paint, such as insufficient hardness and poor hydrophobic effect, can be solved simultaneously without modifying the fillers, and the overall hydrophobic weather-resistant performance of the coating is significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a high weather-resistant multicolor coating and its preparation method. Background Technology

[0002] Multicolor coatings, as common decorative coatings, possess excellent decorative adaptability and ease of application, enabling the creation of diverse decorative appearances. They are widely used in building exteriors, municipal structures, outdoor curtain walls, and industrial decoration. However, with the increasing demands in the coating industry for coating lifespan, outdoor environmental adaptability, and coating structural stability, the shortcomings of conventional multicolor coatings in terms of overall protective performance are becoming increasingly apparent. Conventional products struggle to withstand complex conditions such as high temperature and humidity, strong ultraviolet radiation, and repeated rain and wind erosion. Therefore, developing multicolor coatings with high hydrophobicity, high hardness, long-lasting weather resistance, and structural stability has become an important research direction in this field.

[0003] Currently, most commercially available multicolor coatings use pure acrylic emulsions and styrene-acrylic emulsions as the main film-forming matrix. These resins have good film-forming properties and controllable costs, but their molecular structure has weak resistance to ultraviolet aging, insufficient high-temperature resistance, and insufficient hydrolysis resistance, resulting in low film density and surface hardness. When the coating is exposed to outdoor environments for a long time, it is prone to problems such as resin photodegradation, matrix chalking, film cracking, and increased water absorption, causing the overall weather resistance of the coating to decline rapidly. This not only affects the integrity of the product's appearance but also easily leads to potential problems such as substrate corrosion.

[0004] To address the insufficient weather resistance of multicolor coatings, existing industry modification methods have significant limitations. One approach involves adding additives such as UV absorbers and antioxidants to delay aging. However, these additives have poor erosion and aging resistance, and are prone to loss and failure after long-term outdoor use, only providing short-term improvements in appearance and failing to fundamentally enhance the structural strength and weather resistance of the coating substrate. Another approach involves physical blending modification with ordinary organosilicon monomers, leveraging the UV and high-temperature resistance of organosilicon to optimize coating performance. However, simple physical blending suffers from poor resin compatibility, easy system stratification and precipitation, and decreased overall coating stability. Furthermore, the amount of organosilicon added is limited, resulting in limited improvement in coating hardness, hydrophobicity, and weather resistance. Simultaneously, traditional modified systems lack sufficient hydrophobic shielding capabilities, allowing water vapor, salt spray, and corrosive media to easily penetrate the coating film, continuously accelerating coating aging and failure.

[0005] Current weather-resistant multicolor coatings generally neglect the inherent synergistic relationship between hydrophobicity, coating hardness, and weather resistance. Aging and damage to outdoor coatings mostly begin with surface water retention, contaminant adhesion and penetration, and erosion by various media. Insufficient hydrophobicity leads to long-term adhesion and penetration of moisture and contaminants into the coating, inducing resin hydrolysis, structural loosening, and blistering and peeling of the paint film. Conversely, low coating hardness results in poor resistance to erosion, abrasion, and external forces, further exacerbating structural damage caused by UV aging and acid / alkali corrosion. Existing technologies often use single additives to modify and improve hydrophobicity, but these modified systems suffer from poor stability and durability. The hydrophobic effect rapidly diminishes over time, failing to form a long-term, stable protective system and making it difficult to fundamentally improve the overall weather resistance of the coating.

[0006] Currently, there are few mature technical solutions in this field that precisely blend organosilicon polyurethane film-forming matrix with multifunctional inorganic fillers for use in multicolor coatings. Existing technologies typically require the modification of inorganic fillers using hydrophobic silane coupling agents. For example, CN120554941A discloses a high-performance coating comprising the following components by weight: 120-150 parts of aqueous polyurethane dispersion, 5-15 parts of graphene modified with long-chain fluorinated silane coupling agent, 10-15 parts of carbon nanotubes modified with long-chain fluorinated silane coupling agent, and 1-4 parts of hollow glass microspheres modified with long-chain fluorinated silane coupling agent. CN120399551A also discloses a technique for improving the hydrophobicity of fillers such as carbon nanotubes treated with hydrophobic silane coupling agents. However, all of the above patents require hydrophobic silane modification of the fillers, which is a complex process and cannot simultaneously achieve basic decorative effects and long-term protective performance. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing multicolor coatings, such as poor weather resistance, low hardness, weak hydrophobicity, and insufficient structural stability, and to provide a high-weather-resistant multicolor coating and its preparation method. This invention uses organosilicon polyurethane as the film-forming matrix, combined with two-dimensional planar boron nitride nanosheets, spherical nano-silica particles, and polyurethane-like fluffy micropowder to construct a multi-component synergistic functional system. With the addition of suitable additives and solvents, while ensuring the stability of the coating during storage and application and retaining its basic multicolor decorative characteristics, it significantly improves the coating's density, surface hardness, and hydrophobic shielding ability, achieving a simultaneous improvement in the coating's mechanical properties, hydrophobic properties, and weather resistance.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: The composition comprises 80-100 parts of organosilicon polyurethane, 10-15 parts of boron nitride nanosheets, 4-8 parts of nano-silica particles, 2-5 parts of polyurethane-like fluffy micro powder, 1-8 parts of additives, and 100-500 parts of solvent; wherein the average particle size of the nano-silica particles is greater than or equal to 500 nm.

[0009] Using organosilicon polyurethane as the main film-forming resin, the coating film is endowed with intrinsic low surface energy, hydrolysis resistance, and UV resistance. Furthermore, the ternary components, which include boron nitride nanosheets for barrier, small-particle-size nano-silica particles to construct a micro-nano hydrophobic structure, and polyurethane fluff micropowder to assist in optimizing the coating film structure, simultaneously solve the technical problems of insufficient hardness, poor hydrophobic effect, severe media penetration, and easy aging failure of traditional coatings, significantly improving the overall weather resistance and durability of the coating.

[0010] The silicone polyurethane mentioned herein is a conventional silicone polyurethane in the art, and its type is not particularly limited; any commonly used type in the art is acceptable. Specifically, it can be prepared using polytetrahydrofuran ether diol, 4,4′-diphenylmethane diisocyanate, and hydroxyl-terminated polydimethylsiloxane as the main raw materials, and with chain extenders such as butanediol. The content of hydroxyl-terminated polydimethylsiloxane in the silicone polyurethane is 1-10 wt%. In particular, its main preparation process can be as follows: under nitrogen protection, using N,N-dimethylformamide as a solvent, adding 4,4′-diphenylmethane diisocyanate, polytetrahydrofuran ether diol, hydroxyl-terminated polydimethylsiloxane, and other reaction monomers, reacting at 55°C for 2 hours, and then adding 1,4-butanediol dropwise for 2 hours to obtain the silicone polyurethane; in the reaction system, n(-NCO) / n(-OH) = 1.25; the content of hydroxyl-terminated polydimethylsiloxane is 6 wt%. Furthermore, the silicone polyurethane of the present invention can be added in solution form. In this invention, the amount of organosilicon polyurethane used refers to the effective amount of organosilicon polyurethane in the solution (i.e., the effective content of solids).

[0011] In one embodiment, the type of boron nitride nanosheets is not particularly limited, and any type commonly used in the art is acceptable. Generally, the average lateral size of the boron nitride nanosheets is 1-10 μm. Specifically, the average lateral size of the boron nitride nanosheets can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. Further, the amount of boron nitride nanosheets can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, or 15 parts. In particular, the amount of boron nitride nanosheets is 11-14 parts. Boron nitride nanosheets possess excellent UV shielding performance, chemical stability, and sheet barrier effect. Appropriately sized and used boron nitride nanosheets can form a labyrinthine shielding structure within the coating film, effectively blocking the penetration of water vapor, oxygen, and corrosive media, improving the weather resistance stability of the coating, and also facilitating the formation of micro-nano rough structures, improving the hydrophobicity and hardness of the coating, effectively avoiding the negative impact on the micro-nano structure of the coating caused by excessively large boron nitride size or excessive dosage.

[0012] In one embodiment, the average particle size of the nano-silica particles is 500nm-1000nm (i.e., volume average particle size D50). Specifically, the average particle size of the nano-silica particles can be 500nm, 600nm, 700nm, 800nm, 900nm, or 1000nm. Using nano-silica particles of suitable particle size can construct a uniform and stable micro-nano rough structure on the coating surface. Combined with the low surface energy characteristics of organosilicon polyurethane, a stable hydrophobic interface is formed, significantly improving the water contact angle and self-cleaning ability of the paint film. If the particle size is too small, the particles are prone to agglomeration, and the microscopic undulations on the surface after accumulation are too small, making it difficult to form the micro-nano two-level rough structure required for the lotus leaf effect. The improvement in water contact angle is limited, and the hydrophobic self-cleaning effect is significantly worse. If the particle size is too large, the self-weight is high, and the settling rate in the coating system is fast, which reduces the coating hardness and hydrophobic properties.

[0013] In one embodiment, the polyurethane-based fluff powder is one or more of aliphatic polyurethane-based fluff powder or aromatic polyurethane-based fluff powder. Aliphatic polyurethane-based fluff powder exhibits excellent resistance to yellowing and strong UV aging stability, making it suitable for outdoor coating applications under long-term corrosive conditions; aromatic polyurethane-based fluff powder has moderate elastic modulus and high mechanical strength. Using the two types of polyurethane fluff powder alone or in combination can better construct a micro-nano rough structure, while simultaneously enhancing the overall mechanical deformation resistance of the paint film.

[0014] In one embodiment, the type of polyurethane-based fluff powder is not particularly limited, and any commonly used type in the art is acceptable. Polyurethane-based fluff powders offer a rich variety of colors; selecting different polyurethane-based fluff powders can impart different colors to the coating, resulting in a multi-colored coating. Generally, the fluff powder particle size is between 1-60 µm. Specifically, the polyurethane-based fluff powder can be selected from Microchem's DECOSOFT 7, DECOSOFT 15, DECOSOFT 18, DECOSOFT 30, DECOSOFT 60, etc. Further, the amount of polyurethane-based fluff powder can be 2 parts, 3 parts, 4 parts, or 5 parts; particularly, it can be 2.5-4.5 parts. Insufficient addition of fluff powder cannot fully fill the microscopic voids between boron nitride nanosheets and nano-silica particles, reducing the coating's density and indirectly decreasing its hydrophobicity and weather resistance. Excessive dosage can easily lead to the formation of too many protruding particles on the coating surface, reducing the smoothness of the paint film and disrupting the appropriate micro-nano hydrophobic structure ratio, resulting in a decrease in the water contact angle. In particular, polyurethane fluffy micro powders of different particle sizes can be compounded and used. Compared with single-particle-size fluffy micro powders, multi-level particle size combination filling can significantly optimize the micro-deposition structure of the coating, further improve the density of the coating, and thus synergistically improve the overall hardness and hydrophobic effect. While giving the coating a colorful decorative effect, it also optimizes the micro-structure of the paint film and helps to improve the density and surface hydrophobicity of the paint film.

[0015] Existing technologies generally improve the contact angle of coatings by constructing micro-nano rough structures or hydrophobic modification. However, hydrophobic modification usually requires the use of hydrophobic silane coupling agents, which is not only complex but also prone to causing environmental problems. The boron nitride nanosheets used in this invention have excellent hydrophobic properties and good mechanical strength. High-doped boron nitride nanosheets are used as the weather-resistant enhancement main functional phase in this system. The sheet structure has uniform lateral dimensions and can be stacked in large quantities inside the paint film to form a dense labyrinth-like shielding network, which significantly extends the penetration path of water vapor, oxygen and corrosive media. At the same time, it has excellent ultraviolet scattering and shielding capabilities, forming the core framework of the coating for long-lasting weather resistance, hydrophobicity and high hardness. Nano-silica particles also possess excellent hardness and hydrophobic properties, facilitating particle dispersion in the resin matrix. They serve as the hydrophobic structural reinforcement phase in this system. With a particle size controlled to be greater than or equal to 500 nm, they can uniformly construct a stable micro-nano rough morphology on the paint film surface. Combined with the low surface energy characteristics of organosilicon polyurethane, this forms a highly efficient hydrophobic interface, significantly improving the coating's water contact angle and self-cleaning ability, solving the problems of water accumulation, staining, and poor hydrophobic durability in traditional coatings. Meanwhile, trace amounts of richly colored polyurethane-like fluffy micropowders serve as the structural filler and interface optimization phase in this system. They can uniformly fill the gaps between boron nitride layers and the pores of nano-silica particles, effectively filling microscopic defects in the paint film, refining the coating structure, and improving the overall density of the paint film. Simultaneously, they improve the interfacial compatibility between inorganic fillers and organic resins, alleviating microcrack defects easily caused by inorganic fillers, stabilizing the hydrophobic interface, and making the coating's mechanical and hydrophobic properties more uniform and stable, while also imparting a colorful decorative effect to the coating base. By utilizing the morphology and size effects among two-dimensional boron nitride nanosheets, spherical nano-silica particles, and polyurethane-like fluffy micropowder, a micro-nano rough structure is formed on the coating surface. The synergistic mechanism of "layer barrier enhancement + micro-nano structure hydrophobicity + interface densification reinforcement" formed among the three components can simultaneously improve the coating's hardness, hydrophobicity, structural stability, and weather resistance.

[0016] In one embodiment, a high weather-resistant multicolor coating comprises the following components in parts by weight: The composition comprises 85-95 parts of silicone polyurethane, 11-13.5 parts of boron nitride nanosheets, 5-7.5 parts of nano-silica particles, 2.5-3.5 parts of polyurethane-like fluffy micro powder, 2-8 parts of additives, and 150-400 parts of solvent; wherein the average particle size of the nano-silica particles is greater than or equal to 500 nm.

[0017] In one embodiment, the mass ratio of boron nitride nanosheets, nano-silica particles, and polyurethane-based fluff powder is (3-5):(1.5-2.5):1.

[0018] In particular, this invention utilizes the morphology and size effect between two-dimensional boron nitride nanosheets, spherical nano-silica particles, and polyurethane-like fluffy micropowders, without requiring silane coupling agent modification of the filler, and further improves its dispersion performance in the resin system while maintaining its basic properties.

[0019] In one embodiment, the additive is one or more of the following: anti-settling agent, defoamer, wetting and dispersing agent, leveling agent, preservative, and antibacterial agent.

[0020] In one embodiment, the anti-settling agent is selected from one or more of organic bentonite, polyamide wax, polyethylene wax, and polyphosphate copolymers, which can effectively prevent the inorganic nanofiller from settling and agglomerating, and improve the storage stability of the system.

[0021] In one embodiment, the defoamer is selected from one or more of fluorosilicone modified polysiloxane defoamers, polyether modified organosilicon defoamers, and polydimethylsiloxane defoamers, which can quickly eliminate bubbles in the system and ensure a smooth and dense paint film.

[0022] In one embodiment, the wetting and dispersing agent is selected from one or more of the following: unsaturated polycarboxylic acid polymer, sodium polyacrylate, triethylhexyl phosphate, sodium dodecyl sulfate, methylpentanol, polyacrylamide, glucon, and fatty acid polyethylene glycol ester, to ensure that each functional filler is uniformly dispersed in the resin system without agglomeration or precipitation.

[0023] In one embodiment, the solvent is one or more of butanone, cyclohexanone, methylcyclohexanone, methyl isobutyl ketone, acetone, butyl acetate, toluene, and xylene. It has strong dissolving power, excellent compatibility with organosilicon polyurethane resin and various fillers, and can ensure uniform dispersion and good leveling properties of the system during construction.

[0024] On the other hand, the present invention also provides a method for preparing the above-mentioned high weather-resistant multicolor coating, comprising the following steps: (1) Weigh out the following ingredients by weight: organosilicon polyurethane, boron nitride nanosheets, nano silica particles, polyurethane fluff powder, additives, and solvents. (2) Disperse all components evenly in a reactor to obtain a high weather-resistant multicolor coating. This preparation method is simple, highly controllable, and suitable for large-scale production.

[0025] Beneficial effects: 1. Using silicone polyurethane as the resin matrix, and combining boron nitride nanosheets, nano-silica particles with a suitable particle size of 500nm or above with polyurethane fluff powder, high-hardness inorganic fillers are uniformly filled into the interior of the coating film network structure, which can significantly improve the surface hardness, wear resistance, scratch resistance and resistance to external damage of the coating, effectively improve the problems of low hardness, easy wear and insufficient structural strength of traditional organic coatings, and improve the overall structural durability of the coating.

[0026] 2. This invention forms a triple hydrophobic protection system of "intrinsic low surface energy of resin + micro-nano rough structure + sheet-like physical barrier": organosilicon polyurethane provides a stable low surface energy substrate, and utilizes the morphology and size effect between two-dimensional boron nitride nanosheets, spherical nano silica particles and polyurethane fluff-like micro powder to form a micro-nano rough structure on the coating surface. The synergistic mechanism of "sheet-like barrier enhancement + micro-nano structure hydrophobicity + interface densification and reinforcement" formed among the three achieves the simultaneous improvement of coating hardness, hydrophobicity, structural stability and weather resistance.

[0027] 3. This invention, combined with a suitable system of wetting, dispersing, anti-settling, and defoaming additives, effectively solves the problems of easy agglomeration and sedimentation of nanofillers. Each component exhibits excellent compatibility with the organosilicon polyurethane matrix, ensuring the coating exhibits no stratification, precipitation, or sedimentation during long-term storage. Simultaneously, the solvent system demonstrates good solubility and compatibility, resulting in excellent coating leveling properties, uniform and dense film formation, and convenient application, making it suitable for industrial mass production and engineering coating applications.

[0028] 4. The preparation process of this invention is simple, involves few steps, and is highly controllable, requiring no complex equipment and keeping production costs under control. While retaining the basic colorful decorative effect of the coating, it achieves multiple performance improvements in coating hardness and hydrophobicity, solving the industry problems of weak protective performance and poor durability of traditional multicolor coatings. It is suitable for various high-weather-resistant coating scenarios and has extremely high application value and promotion prospects. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] The coating preparation process in the following examples and comparative examples is as follows: (1) Weigh out the organosilicon polyurethane, boron nitride nanosheets, nano silica particles, polyurethane fluff powder, additives and solvents according to the weight parts; (2) Disperse each component evenly in a reactor to obtain a high weather-resistant multicolor coating.

[0031] Subsequently, under the same conditions, the hardness of the high weather-resistant multicolor coatings prepared in the examples and comparative examples was tested (refer to GB / T6739-2006), and the contact angle of the coatings was tested using a contact angle measuring instrument.

[0032] Example 1

[0033] A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 80 parts of silicone polyurethane, 10 parts of boron nitride nanosheets (average transverse size 2 μm), 8 parts of nano-silica particles (average particle size 600 nm), 2 parts of velvet micropowder (DECOSOFT 7), 1.1 parts of BYK110, 2.2 parts of polyether-modified silicone, and 300 parts of solvent (a mixture of butyl acetate and xylene in a volume ratio of 1:1.1). The hardness is measured to be 2H, and the contact angle is 155.0°.

[0034] Example 2

[0035] A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 100 parts of silicone polyurethane, 15 parts of boron nitride nanosheets (average transverse size 2 μm), 4 parts of nano-silica particles (average particle size 1000 nm), 4.2 parts of velvet micropowder (DECOSOFT 60), 2.8 parts of BYK110, 0.9 parts of polyether-modified silicone, and 300 parts of solvent (a mixture of butyl acetate and xylene in a volume ratio of 1:1.1). The product was tested and found to have a hardness of 3H and a contact angle of 146.6°.

[0036] Example 3

[0037] A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 90 parts of silicone polyurethane, 13 parts of boron nitride nanosheets (average transverse size 2 μm), 6.5 parts of nano-silica particles (average particle size 500 nm), 5 parts of fluffy micropowder (a 1:1 mass ratio mixture of DECOSOFT 7 and DECOSOFT 18), 2.3 parts of BYK110, 1.7 parts of polyether-modified silicone, and 300 parts of solvent (a 1:1.1 volume ratio mixture of butyl acetate and xylene). The hardness is 2H and the contact angle is 147.2°.

[0038] Example 4

[0039] A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 83 parts of silicone polyurethane, 11 parts of boron nitride nanosheets (average transverse size 2 μm), 5 parts of nano-silica particles (average particle size 800 nm), 2.5 parts of velvet micropowder (DECOSOFT 15), 2 parts of BYK110, 1 part of polyether-modified silicone, and 300 parts of solvent (a mixture of butyl acetate and xylene in a volume ratio of 1:1.1). The hardness was tested to be 2H, and the contact angle was 152.5°.

[0040] Example 5

[0041] A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 90 parts of silicone polyurethane, 13 parts of boron nitride nanosheets (average transverse size 2 μm), 6.5 parts of nano-silica particles (average particle size 500 nm), 3 parts of fluffy micropowder (a 1:1 mass ratio mixture of DECOSOFT 7 and DECOSOFT 18), 2.3 parts of BYK110, 1.7 parts of polyether-modified silicone, and 300 parts of solvent (a 1:1.1 volume ratio mixture of butyl acetate and xylene). The hardness is 3H and the contact angle is 155.2°.

[0042] Example 6

[0043] A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 85 parts of silicone polyurethane, 12 parts of boron nitride nanosheets (average transverse size 2 μm), 5.5 parts of nano-silica particles (average particle size 600 nm), 3.2 parts of velvet micropowder (DECOSOFT 18), 1.5 parts of BYK110, 1.3 parts of polyether-modified silicone, and 300 parts of solvent (a mixture of butyl acetate and xylene in a volume ratio of 1:1.1). The hardness is measured to be 2H, and the contact angle is 148.7°.

[0044] Example 7

[0045] A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 90 parts of silicone polyurethane, 13 parts of boron nitride nanosheets (average transverse size 2 μm), 6.5 parts of nano-silica particles (average particle size 500 nm), 3 parts of velvet micropowder (DECOSOFT 7), 2.3 parts of BYK110, 1.7 parts of polyether-modified silicone, and 300 parts of solvent (a mixture of butyl acetate and xylene in a volume ratio of 1:1.1). The product was tested and found to have a hardness of 3H and a contact angle of 151.3°.

[0046] Example 8

[0047] A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 95 parts of silicone polyurethane, 14 parts of boron nitride nanosheets (average transverse size 2 μm), 7 parts of nano-silica particles (average particle size 800 nm), 4 parts of velvet micropowder (DECOSOFT 60), 1.8 parts of BYK110, 1.5 parts of polyether-modified silicone, and 300 parts of solvent (a mixture of butyl acetate and xylene in a volume ratio of 1:1.1). The hardness is 3H and the contact angle is 150.4°.

[0048] Example 9

[0049] A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 92 parts of silicone polyurethane, 13.5 parts of boron nitride nanosheets (average transverse size 2 μm), 6 parts of nano-silica particles (average particle size 800 nm), 3.6 parts of velvet micropowder (DECOSOFT 7), 2.6 parts of BYK110, 1.0 part of polyether-modified silicone, and 300 parts of solvent (a mixture of butyl acetate and xylene in a volume ratio of 1:1.1). The hardness is measured to be 3H, and the contact angle is 149.8°.

[0050] Example 10

[0051] A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 90 parts of silicone polyurethane, 13 parts of boron nitride nanosheets (average transverse size 2 μm), 6.5 parts of nano-silica particles (average particle size 500 nm), 3 parts of velvet micropowder (DECOSOFT 18), 2.3 parts of BYK110, 1.7 parts of polyether-modified silicone, and 300 parts of solvent (a mixture of butyl acetate and xylene in a volume ratio of 1:1.1). The hardness was measured to be 2H, and the contact angle was 153.2°.

[0052] Comparative Example 1 A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 90 parts of silicone polyurethane, 0 parts of boron nitride nanosheets (average transverse size 2 μm), 15.5 parts of nano-silica particles (average particle size 500 nm), 7 parts of fluffy micropowder (DECOSOFT 18), 2.3 parts of BYK110, 1.7 parts of polyether-modified silicone, and 300 parts of solvent (a mixture of butyl acetate and xylene in a volume ratio of 1:1.1). The hardness is H, and the contact angle is 130.1°.

[0053] Comparative Example 2 A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 90 parts of silicone polyurethane, 18.4 parts of boron nitride nanosheets (average transverse size 2 μm), 0 parts of nano-silica particles (average particle size 500 nm), 4.1 parts of velvet micropowder (DECOSOFT 18), 2.3 parts of BYK110, 1.7 parts of polyether-modified silicone, and 300 parts of solvent (a mixture of butyl acetate and xylene in a volume ratio of 1:1.1). The hardness is H, and the contact angle is 132.2°.

[0054] Comparative Example 3 A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 90 parts of silicone polyurethane, 15.0 parts of boron nitride nanosheets (average transverse size 2 μm), 7.5 parts of nano-silica particles (average particle size 500 nm), 0 parts of velvet micropowder (DECOSOFT 18), 2.3 parts of BYK110, 1.7 parts of polyether-modified silicone, and 300 parts of solvent (a mixture of butyl acetate and xylene in a volume ratio of 1:1.1). The hardness is measured to be 2H, and the contact angle is 136.8°.

[0055] Comparative Example 4 A highly weather-resistant multicolor coating comprises the following components in parts by weight: The composition includes 90 parts of silicone polyurethane, 13 parts of boron nitride nanosheets (average transverse size 2 μm), 6.5 parts of nano-silica particles (average particle size 200 nm), 3 parts of velvet micropowder (DECOSOFT 18), 2.3 parts of BYK110, 1.7 parts of polyether-modified silicone, and 300 parts of solvent (a mixture of butyl acetate and xylene in a volume ratio of 1:1.1). The hardness is measured to be 2H, and the contact angle is 139.4°.

[0056] As can be seen from the above embodiments and comparative examples, this invention uses organosilicon polyurethane as the main film-forming resin, and then employs a ternary component consisting of boron nitride nanosheets for barrier, small-diameter nano-silica particles to construct a micro-nano hydrophobic structure, and polyurethane fluff powder to assist in optimizing the film structure. This simultaneously solves the technical problems of insufficient hardness, poor hydrophobicity, and easy aging and failure in traditional coatings, significantly improving the overall weather resistance of the coating. This invention utilizes the morphology and size effects between two-dimensional boron nitride nanosheets, spherical nano-silica particles, and polyurethane fluff powder, eliminating the need for silane coupling agent modification of the filler, and further improving its dispersion performance in the resin system while maintaining its basic properties.

[0057] Specifically, compared to Example 10, Comparative Examples 1, 2, and 3 lacked boron nitride nanosheets, nano-silica particles, and polyurethane fluff powder, respectively, resulting in a certain degree of reduction in coating hardness and contact angle. This is because the high-doped boron nitride nanosheets are the main functional phase for weather resistance enhancement in this system. The uniform transverse dimensions of these sheets allow them to be stacked in large quantities within the paint film to form a dense labyrinthine shielding network, constituting the core framework for the coating's long-lasting weather resistance, hydrophobicity, and high hardness. Nano-silica particles also possess good hardness and hydrophobic properties, uniformly constructing stable micro-nano rough morphologies on the paint film surface. Combined with the low surface energy characteristics of organosilicon polyurethane, they form a highly efficient hydrophobic interface, significantly improving the coating's water contact angle and self-cleaning ability. The trace amounts of richly colored polyurethane fluffy micropowder serve as the structural filler and interface optimization phase in this system. It can uniformly fill the gaps between boron nitride nanosheets and the pores of nano-silica particles, effectively filling microscopic defects in the coating film, refining the coating structure, and improving the overall density of the coating film. Simultaneously, it improves the interfacial compatibility between inorganic fillers and organic resins, alleviates microcrack defects easily caused by inorganic fillers, stabilizes the hydrophobic interface, and makes the coating's mechanical and hydrophobic properties more uniform and stable, thus simultaneously improving the coating's hardness, hydrophobicity, structural stability, and weather resistance. When any one of the components—boron nitride nanosheets, nano-silica particles, or polyurethane fluffy micropowder—is lacking, the micro / nano rough structure cannot be effectively constructed, leading to a decrease in coating performance. Specifically, compared to Example 10, Comparative Example 4 uses smaller-sized nano-silica particles, which are prone to agglomeration. After accumulation, the surface micro-undulations are too small, making it difficult to form the micro / nano two-level rough structure required for the lotus leaf effect. The increase in water contact angle is limited, and the hydrophobic effect is significantly worse.

[0058] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described; these embodiments not explicitly stated should also be considered within the scope of this specification. Although the present invention has been described in detail above with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A high weather-resistant multicolor coating, characterized in that, It contains the following components in parts by weight: The composition comprises 80-100 parts of silicone polyurethane, 10-15 parts of boron nitride nanosheets, 4-8 parts of nano-silica particles, 2-5 parts of polyurethane-like fluff powder, 1-8 parts of additives, and 100-500 parts of solvent; the silicone polyurethane is prepared by chain extension using polytetrahydrofuran ether diol, 4,4′-diphenylmethane diisocyanate, and hydroxyl-terminated polydimethylsiloxane as raw materials; the nano-silica particles have a volume average particle size D50 of 500nm-1000nm.

2. The high weather-resistant multicolor coating as described in claim 1, characterized in that, The chain extender uses butanediol as the chain extender.

3. The high weather-resistant multicolor coating as described in claim 1, characterized in that, The additives are one or more of the following: anti-settling agents, defoamers, wetting and dispersing agents, leveling agents, preservatives, and antibacterial agents.

4. The high weather-resistant multicolor coating as described in claim 3, characterized in that, The anti-settling agent is one or more of organic bentonite, polyamide wax or polyethylene wax, and polyphosphate copolymers.

5. The high weather-resistant multicolor coating as described in claim 3, characterized in that, The defoamer is one or more of the following: fluorosilicone modified polysiloxane defoamer, polyether modified organosilicon defoamer, and polydimethylsiloxane defoamer.

6. The high weather-resistant multicolor coating as described in claim 1, characterized in that, The solvent is one or more of the following: butanone, cyclohexanone, methylcyclohexanone, methyl isobutyl ketone, acetone, butyl acetate, toluene, and xylene.

7. The high weather-resistant multicolor coating as described in claim 1, characterized in that, It contains the following components in parts by weight: The composition comprises 85-95 parts of organosilicon polyurethane, 11-13.5 parts of boron nitride nanosheets, 5-7.5 parts of nano-silica particles, 2.5-3.5 parts of polyurethane-like fluffy micro powder, 2-8 parts of additives, and 150-400 parts of solvent; wherein the volume average particle size D50 of the nano-silica particles is 500nm-1000nm.

8. The high weather-resistant multicolor coating as described in claim 1, characterized in that, The mass ratio of boron nitride nanosheets, nano-silica particles, and polyurethane-based fluff powder is (3-5):(1.5-2.5):

1.

9. The method for preparing a high weather-resistant multicolor coating as described in claim 1, characterized in that, Includes the following steps: (1) Weigh out the following components by weight: organosilicon polyurethane, boron nitride nanosheets, nano silica particles, polyurethane fluff powder, additives, and solvents. (2) Disperse each component evenly in a reactor to obtain a high weather-resistant multicolor coating.