A high-performance environmentally friendly coating and a galvanized sheet prepared therefrom

Abstract

The present invention relates to the technical field of coatings, and particularly to a high-performance environmental protection coating and a galvanized sheet prepared therefrom. The high-performance environmental protection coating comprises the following components in parts by weight: 120-150 parts of an aqueous polyurethane dispersion, 10-15 parts of graphene oxide nanosheets, 4-10 parts of boron nitride nanosheets, 2-6 parts of inorganic nanoparticles, 0.5-2 parts of an anti-settling agent, 0.5-2 parts of an anti-foaming agent, 0.2-2 parts of a wetting and dispersing agent, and 50-100 parts of deionized water. By selecting inorganic nanoparticles with a specific particle size, they can be dispersed between the boron nitride nanosheets and the graphene oxide nanosheets, playing a role similar to that of a bearing in dispersion and lubrication, improving the isolation and shielding effects of the nanosheet materials, and enhancing the stability of the coating.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and particularly to a high-performance environmental protection coating and a galvanized sheet prepared therefrom. Background Art

[0002] Galvanized sheets have excellent corrosion resistance and excellent processing and forming properties, and are widely used in industries such as household appliances and automobiles. However, galvanized sheets will undergo chemical reactions with substances such as water vapor and oxygen in a humid environment, resulting in surface corrosion of the coating. To ensure that the product does not rust during storage and transportation, the surface of the galvanized sheet generally needs to be passivated.

[0003] To solve the above problems, a thin film material is coated on the surface of the galvanized sheet to reduce its surface energy, so that the coating has high mechanical properties while also having other properties such as corrosion resistance, alkali wash resistance, and blackening resistance.

[0004] Polyurethane is a type of polymer with typical urethane functional groups, which are usually obtained by reacting polyisocyanates with hydroxyl components of polyethers, polyesters, hydroxyacrylic acids, and hydroxy alkyds under the condition of some suitable additives. Due to its excellent properties, such as good wear resistance, corrosion resistance, adhesion, chemical stability, and the controllability of hard and soft segments, polyurethane is widely used in fields such as life, medicine, industry, and even national defense.

[0005] According to the different dispersion media, polyurethane can be currently divided into two major categories: solvent-based polyurethane and waterborne polyurethane. Waterborne polyurethane is a new type of polyurethane system with water as the dispersion medium, also known as water-dispersed polyurethane, water-based polyurethane, or water-based polyurethane. Since there is no or a small amount of organic solvents in the system, it can meet the increasingly strict environmental protection requirements, and the harm to human health and environmental pollution is relatively much smaller. Although waterborne polyurethane has the advantages of environmental friendliness and environmental protection, it still lags behind solvent-based polyurethane in terms of film-forming curing time, mechanical properties, water resistance, heat resistance, and chemical stability.

[0006] With the development of polyurethane, humans have increasingly focused on the development of high-efficiency and high-performance coatings. Conventional polyurethane can no longer meet the requirements due to its defects in performance and application. The modification of polyurethane has become one of the research hotspots in this field and has achieved rapid development. According to different modifiers, the modification of polyurethane is divided into structural modification and nano-filler modification.

[0007] Among them, nanomaterials have characteristics such as surface effect, small size effect, quantum size effect, and macroscopic quantum tunneling effect, thus exhibiting unique acoustic, optical, electrical, magnetic, thermal, and mechanical properties. Adding them to the polyurethane matrix can endow new superposition effects and significantly affect the properties of the composite material with extremely low content. Nanomaterials can not only improve the comprehensive properties such as electricity, heat, and mechanics of traditional polyurethane, but also enhance its barrier properties. However, due to the small size of nanomaterials, they have a large specific surface area and surface energy, and are prone to agglomeration, unable to be well dispersed in the polyurethane matrix and fused with the polyurethane matrix. Therefore, how to avoid the agglomeration of nanomaterials and improve the dispersibility and compatibility of nanomaterials in the polyurethane matrix is a key issue in the modification of polyurethane coatings with nanomaterials. Summary of the Invention

[0008] Aiming at the above problems, the purpose of the present invention is to provide a high-performance environmental protection coating and a galvanized sheet prepared therefrom. The coating of the present invention not only has excellent mechanical properties, but also has easy construction and weather resistance, and has broad application prospects.

[0009] The technical solution of the present invention is realized as follows:

[0010] A high-performance environmental protection coating, comprising the following components in parts by weight:

[0011] 120 - 150 parts of aqueous polyurethane dispersion, 10 - 15 parts of graphene oxide nanosheets, 4 - 10 parts of boron nitride nanosheets, 2 - 6 parts of inorganic nanoparticles, 0.5 - 2 parts of anti-settling agent, 0.5 - 2 parts of defoaming agent, 0.2 - 2 parts of wetting and dispersing agent, 50 - 100 parts of deionized water; the volume average particle size (D50) of the inorganic nanoparticles is 100 - 200 nm.

[0012] Graphene oxide is a typical two-dimensional oxygen-containing graphene derivative with a large number of oxygen-containing functional groups, such as hydroxyl and epoxy groups at the bottom of the plane, and carbonyl groups at the edges. Compared with graphene, the oxygen-containing functional groups on the surface of graphene oxide have greater reaction activity, endowing it with different properties from graphene. It has better water solubility, and the surface active groups can react with polyurethane or form hydrogen bonds, and has better compatibility with aqueous polyurethane. Due to the existence of active groups, graphene oxide is easy to adhere to the surface of metal sheets, effectively inhibiting the metal oxidation behavior and blocking the occurrence of pitting corrosion as a charge transfer barrier. However, due to the existence of defects, the mechanical properties of graphene oxide are poor, affecting the mechanical properties of the coating. In order to improve the mechanical properties of the coating, a certain amount of boron nitride nanosheets and inorganic nanoparticles are added in the present invention.

[0013] Boron nitride has the same honeycomb atomic structure as graphene, with excellent dielectric properties and high-temperature oxidation resistance. Compared with graphene oxide, boron nitride nanosheets are inexpensive and have excellent thermal stability, thermal conductivity, electrical insulation, and chemical stability. They can be used to improve the mechanical properties and friction resistance of polymer coatings, making the coatings immune to galvanic corrosion. At the same time, since both boron nitride nanosheets and graphene oxide nanosheets exhibit a lamellar structure, graphene oxide can improve the dispersion performance of the inert filler - boron nitride nanosheets, effectively solving the problem of poor compatibility between boron nitride nanosheets and the matrix and enhancing their dispersion performance.

[0014] Inorganic nanoparticles usually have hydroxyl groups in different states on their surfaces, causing their surfaces to deviate from their stable structure due to oxygen deficiency and having high activity. They can improve the hardness, compactness, thermal stability, and chemical stability of coatings by bonding with certain groups in the polyurethane matrix. When the particle size of inorganic nanoparticles is too large, it is difficult to exert the size effect. At the same time, due to the high surface activity of inorganic nanoparticles, when their particle size is too small, they are prone to agglomeration in the polymer solution. Attention should be paid to adjusting the particle size of inorganic nanoparticles during use. By selecting inorganic nanoparticles with a specific particle size, they can be dispersed between boron nitride nanosheets and graphene oxide nanosheets, playing a dispersing and lubricating role similar to that of bearings, improving the isolation and shielding effects of the nanosheet materials, and enhancing the stability of the coatings.

[0015] Furthermore, the solid content of the aqueous polyurethane dispersion is 50 - 70%. The type of aqueous polyurethane is not particularly limited and can be prepared by introducing hydrophilic components during the preparation of polyurethane. For example, after reacting polyether diol and diisocyanate for a certain period of time, a hydrophilic chain extender (such as dimethylolbutyric acid) and an amine compound are added and the reaction continues to obtain a prepolymer, and then a small molecule diol is added for chain extension reaction to obtain the aqueous polyurethane dispersion.

[0016] Furthermore, a high-performance environmentally friendly coating comprises the following components in parts by weight: 120 - 150 parts of aqueous polyurethane dispersion, 10 - 15 parts of graphene oxide nanosheets, 6 - 8 parts of boron nitride nanosheets, 3 - 4.5 parts of inorganic nanoparticles, 0.5 - 2 parts of anti-settling agent, 0.5 - 2 parts of defoaming agent, 0.2 - 2 parts of wetting and dispersing agent, and 50 - 100 parts of deionized water. By adjusting the dosage of each component, it is possible to better promote the dispersion of the fillers, facilitate the formation of a dense structure, and improve the hardness and stability of the coatings.

[0017] Further, the mass ratio of the graphene oxide nanosheets, boron nitride nanosheets, and inorganic nanoparticles is 3:2:1. The nanosheet structure has a high aspect ratio. There is no specific limitation on the lateral size of the graphene oxide nanosheets and boron nitride nanosheets used in the present invention, as long as they exhibit a sheet-like structure. Generally, the lateral size of the graphene oxide nanosheets is 0.5 - 10 μm; the lateral size of the boron nitride nanosheets is 0.5 - 10 μm. Further, considering the dispersion and isolation effects, the lateral size of the graphene oxide nanosheets is 1 - 3 μm; the lateral size of the boron nitride nanosheets is 1 - 3 μm. Among them, the average lateral size of the graphene oxide nanosheets used in the present invention is 2 μm; the average lateral size of the boron nitride nanosheets is 1 μm.

[0018] Further, the inorganic nanoparticles are one or a mixture of more than one of nano-silica, nano-titanium dioxide, nano-calcium carbonate, nano-zinc oxide, and nano-zirconium dioxide.

[0019] Further, the anti-settling agent is one or a mixture of more than one of BYK420, BYK425, and BYK430.

[0020] Further, the defoaming agent is an organosilicon defoaming agent or a mineral oil defoaming agent.

[0021] Further, the wetting and dispersing agent is one or a mixture of more than one of sodium polyacrylate salt, ammonium polyacrylate salt, and polyphosphate.

[0022] Further, the preparation method of the high-performance environmental protection coating includes the following steps:

[0023] S1. Weigh each component according to parts by weight;

[0024] S2. After uniformly mixing the graphene oxide nanosheets, boron nitride nanosheets, inorganic nanoparticles, and deionized water, add the aqueous polyurethane dispersion, stir and disperse, and then add the anti-settling agent, defoaming agent, and wetting and dispersing agent, and mix uniformly again to obtain a high-performance environmental protection coating.

[0025] Further, the stirring and dispersing rate is 500 - 1000 r / min.

[0026] On the other hand, the present invention also provides a galvanized sheet, which is obtained by coating the surface of a galvanized sheet that has been cleaned and treated with the high-performance environmental protection coating.

[0027] Beneficial effects: The present invention modifies the waterborne polyurethane coating with graphene oxide nanosheets, boron nitride nanosheets and inorganic nanoparticles. The oxygen-containing functional groups on the surface of graphene oxide have greater reaction activity and better compatibility with waterborne polyurethane. At the same time, due to the presence of active groups, graphene oxide is easily attached to the surface of metal sheets, effectively inhibiting the metal oxidation behavior. Boron nitride nanosheets are inexpensive and can be used to improve the mechanical properties and friction resistance of polymer coatings, so that the coatings are not affected by galvanic corrosion. At the same time, since both boron nitride nanosheets and graphene oxide nanosheets exhibit a lamellar structure, graphene oxide can improve the dispersion performance of the inert filler - boron nitride nanosheets, effectively solving the problem of poor compatibility between boron nitride nanosheets and the matrix and improving its dispersion performance. By selecting inorganic nanoparticles with a specific particle size, they can be dispersed between boron nitride nanosheets and graphene oxide nanosheets, playing a dispersing and lubricating role similar to that of bearings, improving the isolation and shielding effects of the nanosheet materials, and improving the stability of the coatings. Detailed implementation manners

[0028] To better illustrate the purpose, technical solutions and advantages of the present application, the present application will be further described below in conjunction with specific embodiments. In the following examples and comparative examples, the experimental methods used are all conventional methods unless otherwise specified, and the materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified.

[0029] Among them, the average lateral size of the graphene oxide nanosheets used in the following examples and comparative examples is 2 μm; the average lateral size of the boron nitride nanosheets is 1 μm. The specific preparation processes of the following examples and comparative examples are as follows:

[0030] S1. Weigh each component by weight parts;

[0031] S2. After mixing graphene oxide nanosheets, boron nitride nanosheets, inorganic nanoparticles and deionized water evenly, add the waterborne polyurethane dispersion, stir and disperse, and then add an anti-settling agent, an antifoaming agent and a wetting and dispersing agent, and mix evenly again to obtain a high-performance environmental protection coating; the stirring and dispersing rate is 700 r / min.

[0032] Example 1

[0033] A high-performance environmental protection coating, comprising the following components by weight parts:

[0034] 120 parts of aqueous polyurethane dispersion, 10 parts of graphene oxide nanosheets, 6 parts of boron nitride nanosheets, 3 parts of inorganic nanoparticles, 0.5 part of anti-settling agent, 0.5 part of defoaming agent, 0.2 part of wetting and dispersing agent, 60 parts of deionized water; the volume average particle size of the inorganic nanoparticles is 100 nm; the solid content of the aqueous polyurethane dispersion is 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK420; the defoaming agent is polydimethylsiloxane; the wetting and dispersing agent is sodium polyacrylate salt.

[0035] Example 2

[0036] A high-performance environmentally friendly coating, comprising the following components in parts by weight: 150 parts of aqueous polyurethane dispersion, 15 parts of graphene oxide nanosheets, 8 parts of boron nitride nanosheets, 4.5 parts of inorganic nanoparticles, 2 parts of anti-settling agent, 2 parts of defoaming agent, 2 parts of wetting and dispersing agent, 90 parts of deionized water; the volume average particle size of the inorganic nanoparticles is 200 nm; the solid content of the aqueous polyurethane dispersion is 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK425; the defoaming agent is polydimethylsiloxane; the wetting and dispersing agent is ammonium polyacrylate salt.

[0037] Example 3

[0038] A high-performance environmentally friendly coating, comprising the following components in parts by weight: 120 parts of aqueous polyurethane dispersion, 15 parts of graphene oxide nanosheets, 6 parts of boron nitride nanosheets, 4.5 parts of inorganic nanoparticles, 0.5 part of anti-settling agent, 2 parts of defoaming agent, 0.2 part of wetting and dispersing agent, 90 parts of deionized water; the volume average particle size of the inorganic nanoparticles is 100 nm; the solid content of the aqueous polyurethane dispersion is 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK430; the defoaming agent is polydimethylsiloxane; the wetting and dispersing agent is sodium polyacrylate salt.

[0039] Example 4

[0040] A high-performance environmentally friendly coating, comprising the following components in parts by weight: 130 parts of aqueous polyurethane dispersion, 12 parts of graphene oxide nanosheets, 6.5 parts of boron nitride nanosheets, 3.5 parts of inorganic nanoparticles, 1 part of anti-settling agent, 1 part of defoaming agent, 1 part of wetting and dispersing agent, 70 parts of deionized water; the volume average particle size of the inorganic nanoparticles is 130 nm; the solid content of the aqueous polyurethane dispersion is 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK420; the defoaming agent is polydimethylsiloxane; the wetting and dispersing agent is ammonium polyacrylate salt.

[0041] Example 5

[0042] A high-performance environmentally friendly coating, comprising the following components in parts by weight: 140 parts of an aqueous polyurethane dispersion, 14 parts of graphene oxide nanosheets, 7.5 parts of boron nitride nanosheets, 4 parts of inorganic nanoparticles, 1.5 parts of an anti-settling agent, 1.5 parts of an anti-foaming agent, 1.5 parts of a wetting and dispersing agent, and 80 parts of deionized water; the inorganic nanoparticles have a volume average particle size of 180 nm; the aqueous polyurethane dispersion has a solid content of 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK430; the anti-foaming agent is polydimethylsiloxane; the wetting and dispersing agent is sodium polyacrylate salt.

[0043] Example 6

[0044] A high-performance environmentally friendly coating, comprising the following components in parts by weight: 135 parts of an aqueous polyurethane dispersion, 12 parts of graphene oxide nanosheets, 4 parts of boron nitride nanosheets, 4 parts of inorganic nanoparticles, 1 part of an anti-settling agent, 1 part of an anti-foaming agent, 1 part of a wetting and dispersing agent, and 80 parts of deionized water; the inorganic nanoparticles have a volume average particle size of 150 nm; the aqueous polyurethane dispersion has a solid content of 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK420; the anti-foaming agent is polydimethylsiloxane; the wetting and dispersing agent is sodium polyacrylate salt.

[0045] Example 7

[0046] A high-performance environmentally friendly coating, comprising the following components in parts by weight: 135 parts of an aqueous polyurethane dispersion, 12 parts of graphene oxide nanosheets, 10 parts of boron nitride nanosheets, 4 parts of inorganic nanoparticles, 1 part of an anti-settling agent, 1 part of an anti-foaming agent, 1 part of a wetting and dispersing agent, and 80 parts of deionized water; the inorganic nanoparticles have a volume average particle size of 150 nm; the aqueous polyurethane dispersion has a solid content of 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK420; the anti-foaming agent is polydimethylsiloxane; the wetting and dispersing agent is sodium polyacrylate salt.

[0047] Example 8

[0048] A high-performance environmentally friendly coating, comprising the following components in parts by weight: 135 parts of an aqueous polyurethane dispersion, 12 parts of graphene oxide nanosheets, 8 parts of boron nitride nanosheets, 2 parts of inorganic nanoparticles, 1 part of an anti-settling agent, 1 part of an anti-foaming agent, 1 part of a wetting and dispersing agent, and 80 parts of deionized water; the inorganic nanoparticles have a volume average particle size of 150 nm; the aqueous polyurethane dispersion has a solid content of 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK420; the anti-foaming agent is polydimethylsiloxane; the wetting and dispersing agent is sodium polyacrylate salt.

[0049] Example 9

[0050] A high-performance environmental protection coating, comprising the following components in parts by weight: 135 parts of aqueous polyurethane dispersion, 12 parts of graphene oxide nanosheets, 8 parts of boron nitride nanosheets, 6 parts of inorganic nanoparticles, 1 part of anti-settling agent, 1 part of defoaming agent, 1 part of wetting and dispersing agent, 80 parts of deionized water; the inorganic nanoparticles have a volume average particle size of 150 nm; the solid content of the aqueous polyurethane dispersion is 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK420; the defoaming agent is polydimethylsiloxane; the wetting and dispersing agent is sodium polyacrylate salt.

[0051] Example 10

[0052] A high-performance environmental protection coating, comprising the following components in parts by weight: 135 parts of aqueous polyurethane dispersion, 12.5 parts of graphene oxide nanosheets, 6.8 parts of boron nitride nanosheets, 3.6 parts of inorganic nanoparticles, 1.2 parts of anti-settling agent, 0.9 part of defoaming agent, 1.1 parts of wetting and dispersing agent, 75 parts of deionized water; the inorganic nanoparticles have a volume average particle size of 180 nm; the solid content of the aqueous polyurethane dispersion is 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK430; the defoaming agent is polydimethylsiloxane; the wetting and dispersing agent is ammonium polyacrylate salt.

[0053] Example 11

[0054] A high-performance environmental protection coating, comprising the following components in parts by weight: 135 parts of aqueous polyurethane dispersion, 12 parts of graphene oxide nanosheets, 8 parts of boron nitride nanosheets, 4 parts of inorganic nanoparticles, 1 part of anti-settling agent, 1 part of defoaming agent, 1 part of wetting and dispersing agent, 80 parts of deionized water; the inorganic nanoparticles have a volume average particle size of 150 nm; the solid content of the aqueous polyurethane dispersion is 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK420; the defoaming agent is polydimethylsiloxane; the wetting and dispersing agent is sodium polyacrylate salt.

[0055] Comparative Example 1

[0056] A high-performance environmental protection coating, comprising the following components in parts by weight: 135 parts of aqueous polyurethane dispersion, 0 part of graphene oxide nanosheets, 16 parts of boron nitride nanosheets, 8 parts of inorganic nanoparticles, 1 part of anti-settling agent, 1 part of defoaming agent, 1 part of wetting and dispersing agent, 80 parts of deionized water; the inorganic nanoparticles have a volume average particle size of 150 nm; the solid content of the aqueous polyurethane dispersion is 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK420; the defoaming agent is polydimethylsiloxane; the wetting and dispersing agent is sodium polyacrylate salt.

[0057] Comparative Example 2

[0058] A high-performance environmentally friendly coating, comprising the following components in parts by weight: 135 parts of an aqueous polyurethane dispersion, 18 parts of graphene oxide nanosheets, 0 parts of boron nitride nanosheets, 6 parts of inorganic nanoparticles, 1 part of an anti-settling agent, 1 part of an anti-foaming agent, 1 part of a wetting and dispersing agent, and 80 parts of deionized water; the inorganic nanoparticles have a volume average particle size of 150 nm; the aqueous polyurethane dispersion has a solid content of 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK420; the anti-foaming agent is polydimethylsiloxane; the wetting and dispersing agent is sodium polyacrylate salt.

[0059] Comparative Example 3

[0060] A high-performance environmentally friendly coating, comprising the following components in parts by weight: 135 parts of an aqueous polyurethane dispersion, 14.4 parts of graphene oxide nanosheets, 9.6 parts of boron nitride nanosheets, 0 parts of inorganic nanoparticles, 1 part of an anti-settling agent, 1 part of an anti-foaming agent, 1 part of a wetting and dispersing agent, and 80 parts of deionized water; the inorganic nanoparticles have a volume average particle size of 150 nm; the aqueous polyurethane dispersion has a solid content of 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK420; the anti-foaming agent is polydimethylsiloxane; the wetting and dispersing agent is sodium polyacrylate salt.

[0061] Comparative Example 4

[0062] A high-performance environmentally friendly coating, comprising the following components in parts by weight: 135 parts of an aqueous polyurethane dispersion, 12 parts of graphene oxide nanosheets, 8 parts of boron nitride nanosheets, 4 parts of inorganic nanoparticles, 1 part of an anti-settling agent, 1 part of an anti-foaming agent, 1 part of a wetting and dispersing agent, and 80 parts of deionized water; the inorganic nanoparticles have a volume average particle size of 40 nm; the aqueous polyurethane dispersion has a solid content of 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK420; the anti-foaming agent is polydimethylsiloxane; the wetting and dispersing agent is sodium polyacrylate salt.

[0063] Comparative Example 5

[0064] A high-performance environmentally friendly coating, comprising the following components in parts by weight: 135 parts of an aqueous polyurethane dispersion, 12 parts of graphene oxide nanosheets, 8 parts of boron nitride nanosheets, 4 parts of inorganic nanoparticles, 1 part of an anti-settling agent, 1 part of an anti-foaming agent, 1 part of a wetting and dispersing agent, and 80 parts of deionized water; the inorganic nanoparticles have a volume average particle size of 300 nm; the aqueous polyurethane dispersion has a solid content of 60%; the inorganic nanoparticles are nano-silica; the anti-settling agent is BYK420; the anti-foaming agent is polydimethylsiloxane; the wetting and dispersing agent is sodium polyacrylate salt.

[0065] The high-performance environmentally friendly coatings prepared in the examples and comparative examples were subjected to hardness testing (GB / T 6739-2006), film adhesion testing (GB / T 5210-2006), and salt spray resistance testing (GB / T 1771-2007); the results are shown in Table 1.

[0066]

[0067] From the results in Table 1, it can be seen that the present invention uses graphene oxide nanosheets, boron nitride nanosheets, and inorganic nanoparticles to modify the aqueous polyurethane coating. The oxygen-containing functional groups on the surface of graphene oxide have greater reaction activity and better compatibility with the aqueous polyurethane. At the same time, due to the presence of active groups, graphene oxide is easily attached to the surface of metal sheets, effectively inhibiting the metal oxidation behavior. At the same time, since both boron nitride nanosheets and graphene oxide nanosheets have a lamellar structure, graphene oxide can improve the dispersion performance of the inert filler - boron nitride nanosheets, effectively solving the problem of poor compatibility between boron nitride nanosheets and the matrix and improving its dispersion performance. By selecting inorganic nanoparticles with a specific particle size, they can be dispersed between boron nitride nanosheets and graphene oxide nanosheets, playing a dispersion and lubrication role similar to that of bearings, improving the isolation and shielding effect of the nanosheet material, and improving the stability of the coating. Compared with Example 11, when Comparative Examples 1-3 lack graphene oxide nanosheets, boron nitride nanosheets, and inorganic nanoparticles, a specific morphological dispersion system cannot be formed, affecting the coating performance. Comparative Examples 4-5 show that when the particle size of the inorganic nanoparticles is too large, it is difficult to exert the size effect; at the same time, the surface activity of the inorganic nanoparticles is relatively high, and when their particle size is too small, they are prone to agglomeration in the polymer solution, and attention should be paid to adjusting the particle size of the inorganic nanoparticles during use.

[0068] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A high-performance environmentally friendly coating, characterized in that: Contains the following components in parts by weight: 120-150 parts of aqueous polyurethane dispersion, 10-15 parts of graphene oxide nanosheets, 6-8 parts of boron nitride nanosheets, 3-4.5 parts of inorganic nanoparticles, 0.5-2 parts of anti-settling agent, 0.5-2 parts of defoaming agent, 0.2-2 parts of wetting dispersant, and 50-100 parts of deionized water; the volume average particle size of the inorganic nanoparticles is 100-200nm, the lateral size of the graphene oxide nanosheets is 1-3μm; the lateral size of the boron nitride nanosheets is 1-3μm; the solid content of the aqueous polyurethane dispersion is 50-70%; the inorganic nanoparticles are nano-silicon dioxide.

2. A high-performance environmentally friendly coating as claimed in claim 1, characterized in that: The mass ratio of the graphene oxide nanosheets, the boron nitride nanosheets and the inorganic nanoparticles is 3:2:

1.

3. A high-performance environmentally friendly coating as claimed in claim 1, characterized in that: The anti-settling agent is a mixture of one or more of BYK420, BYK425 and BYK430.

4. A high-performance environmentally friendly coating as claimed in claim 1, characterized in that: The defoamer is an organosilicon defoamer or a mineral oil defoamer.

5. A high-performance environmentally friendly coating as claimed in claim 1, characterized in that: The wetting and dispersing agent is a mixture of one or more of polyacrylic acid sodium salt, polyacrylic acid ammonium salt and polyphosphate.

6. A high-performance environmentally friendly coating as claimed in claim 1, characterized in that: The preparation method of the high-performance environmentally friendly coating comprises the following steps: S1. Weigh each component by weight; S2. After the graphene oxide nanosheets, boron nitride nanosheets, inorganic nanoparticles and deionized water are evenly mixed, an aqueous polyurethane dispersion is added, and the mixture is dispersed by stirring. Then, an anti-settling agent, a defoaming agent and a wetting dispersant are added, and the mixture is evenly mixed again to obtain a high-performance environmentally friendly coating.

7. A high-performance environmentally friendly coating as claimed in claim 6, characterized in that: The stirring and dispersing rate is 500-1000 r / min.

8. A galvanized sheet, characterized in that: The high-performance environmentally friendly coating according to any one of claims 1 to 7 is applied on the surface of a cleaned galvanized sheet to obtain the coating.

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