A protective nano hard coating and its preparation method

Abstract

The present invention discloses a protective nano hard coating and a preparation method thereof, which belongs to the field of inorganic coatings. A protective nano hard coating comprises a coating base, a nano inorganic filler, and an additive, characterized in that: the nano inorganic filler comprises a main filler and a functional filler, wherein the amount of the functional filler is 1-8% of the total mass of the nano inorganic filler, and the balance of the nano inorganic filler is the main filler; based on the total mass of the main filler, the main filler is composed of the following components by mass fraction: 15w% to 25w% of nano silicon of 15-20nm, 35w% to 45w% of nano silicon of 25-50nm, and 30w% to 40w% of nano silicon of 55-80nm; wherein the particle size range of the functional filler is 20-50nm. The present invention utilizes particles of three particle size ranges for effective grading, and particles of different particle sizes fill each other to form a dense coating with excellent performance. On this basis, a small amount of functional filler can be used to focus on enhancing certain performance according to different use environments and application objects.

Description

Technical Field

[0001] The invention belongs to the field of inorganic coatings and relates to a protective nano hard coating and a preparation method thereof. Background Art

[0002] Nano-silicon inorganic coating is a new type of coating manufactured using nanotechnology. The particles of nano-coating are very small and can penetrate into the tiny gaps on the surface of the material, providing more comprehensive and lasting protection. Because small particles have a higher specific surface area and can provide more active sites, traditional nano-silicon coatings focus on a narrow range and have a single particle size distribution, usually less than 50nm.

[0003] Although small particles (<50nm) have advantages such as high specific surface area, excellent optical properties and nano-scale functionalization, the processing technology of small particles is complex and difficult. Moreover, precisely because of their extremely high specific surface area, small particles are prone to agglomeration. In the coating, small nanoparticles with a single gradation cannot form a continuous and stable mechanical skeleton structure, and are not suitable for complex environments such as high impact, high corrosion, and frequent erosion. Summary of the Invention

[0004] The purpose of the present invention is to provide a protective nano-hard coating and a preparation method thereof, which solves the problem that traditional nano-silicon coatings currently focus on small particle coatings in a narrow range of less than 50nm. Since the small nano-particles with a single gradation cannot form a continuous and stable mechanical skeleton structure, they are not suitable for complex environments such as high impact, high corrosion, and frequent erosion.

[0005] The technical solution adopted in the present invention is as follows:

[0006] A protective nano hard coating, comprising a coating base, a nano inorganic filler, and an additive, wherein the nano inorganic filler comprises a main filler and a functional filler, wherein the functional filler is added in an amount of 1-8% of the total mass of the nano inorganic filler, and the remainder of the nano inorganic filler is the main filler;

[0007] Based on the total mass of the main filler, the main filler is composed of the following components by mass fraction: 15w% to 25w% of 15-20nm nano-silicon, 35w% to 45w% of 25-50nm nano-silicon, and 30w% to 40w% of 55-80nm nano-silicon;

[0008] Wherein, the particle size range of the functional filler is 20-50 nm.

[0009] Based on the advantages of nano-scale small-particle inorganic coatings, the present invention expands the gradation range through the gradation design of multi-scale nano-silicon particles (15-20nm, 25-50nm, 55-80nm), and solves the problem that traditional small-particle coatings cannot form a continuous and stable mechanical skeleton structure.

[0010] The selection of the gradation range of the present invention comprehensively considers the physical and chemical properties of the particles, the performance requirements of the coating, and the feasibility of the process; the particle size range and the addition ratio of the particles have a significant impact on the particle size formulation, and the effect of the particle size range and the addition ratio on the gradation is not linearly related. For example, increasing the proportion of small particles may increase the reactivity of the coating, but it may also increase the tendency to agglomerate and affect the uniformity of the coating.

[0011] In the present invention, large-particle nanosilicon (55-80nm) provides mechanical support and forms a stable skeleton structure; medium-particle nanosilicon (25-50nm) has a moderate specific surface area and can enhance the mechanical properties of the coating while providing a certain reaction activity; small-particle nanosilicon (15-20nm) has an extremely high specific surface area and can provide more active sites, thereby enhancing the reaction activity and corrosion resistance of the coating; the present invention constructs a stable mechanical skeleton by introducing large particles of 55-80nm, and uses small and medium-sized particles of 15-20nm and 25-50nm to fill the gaps, forming a continuous and stable mechanical structure, thereby significantly improving the mechanical properties of the coating.

[0012] The present invention utilizes particles of three particle size ranges for effective grading. Particles of different particle sizes fill each other to form a dense coating with excellent performance. On this basis, a small amount of functional filler can be used to enhance certain performance according to different usage environments and application objects. The functional filler is added within the particle size range of 20-50nm and will not destroy the mechanical skeleton formed by the main filler.

[0013] Too wide a particle size distribution, such as 10-100 nm, can easily lead to large differences in particle size, affecting the uniformity and mechanical properties of the coating. Too narrow a particle size distribution, such as 30-40 nm, cannot achieve the synergistic effect of multi-scale particles, resulting in single performance and limited use of the coating.

[0014] Nano-silicon has excellent mechanical properties, chemical stability, thermal stability and other properties. Therefore, this application will preferably use nano-silicon as the main component of the protective inorganic coating of this application; the main filler of this application has a single component, which effectively avoids the incompatibility between different substances.

[0015] Furthermore, the 15-20 nm nano-silicon and the 55-80 nm nano-silicon carry the same charge, and the 25-50 nm nano-silicon carries a different charge.

[0016] The main component of the present application is nano-scale silicon particles. The particle size of nano-scale particles is small, and their dispersibility is relatively poor. The present invention also utilizes the principle that like charges repel each other and unlike charges attract each other. While ensuring uniform dispersion of particles, it can also ensure the mutual filling of particles of different particle sizes, making the overall coating uniform and dense.

[0017] In the process of using surface charge modification to achieve particle dispersion and gap filling, the method of large and small particles carrying the same charge and medium particles carrying different charges is preferred; large and small particles can carry positive charges at the same time, and medium particles can carry negative charges at the same time; large and small particles can also carry negative charges at the same time, and medium particles carry positive charges.

[0018] In this application, the large particles carry the same charge, and the repulsion of like charges is utilized to avoid the aggregation of large particles, providing sufficient channels for small and medium particles to enter the gaps between large particles. In the preparation process of inorganic coatings, the large particles have a large particle size. If the large particles are piled together, the small and medium particles are blocked from entering the pores inside them, and a dense coating cannot be formed, and the mechanical properties are unevenly distributed.

[0019] In this application, if the large particles, small particles and medium particles all carry the same charge, over-dispersion will occur, which will reduce the density of filling between the particles.

[0020] In the present application, when the tertiary particles are mixed, the charges of the large and small particles repel each other, and the uniform dispersion provides a good foundation for the filling of the medium particles; the electrostatic attraction of the medium particles provides a filling bridge, which helps to form a dense structure.

[0021] If the large and medium particles carry the same charge and the small particles carry different charges, the large and medium particles will repel each other due to the same charges, resulting in a larger distance between them. Although the small particles will be attracted, it is difficult for them to completely fill the gap between the large and medium particles, thus reducing the density of the coating.

[0022] If the small and medium particles carry the same charge and the large particles carry different charges, the small and medium particles will form a competitive relationship and adsorb on the large particles, forming an uneven dispersion system.

[0023] Furthermore, the auxiliary agent includes a double dispersion system, and the double dispersion system includes a first dispersion system and a second dispersion system;

[0024] The first dispersion system includes composition A and composition B, wherein composition A includes the following components: an aminosilane coupling agent and an anionic surfactant, wherein the aminosilane coupling agent and the anionic surfactant are combined to make the surface of the nano-silicon have a negative charge; and composition B includes the following components: an epoxy silane coupling agent and a cationic surfactant, wherein the epoxy silane coupling agent and the cationic surfactant are combined to make the surface of the nano-silicon have a positive charge.

[0025] The second dispersion system includes PVP dispersant and phospholipid-polyethylene glycol.

[0026] This application utilizes a double dispersion system to, on the one hand, achieve charge modification of the main filler particles to prepare a uniformly distributed and dense mechanical skeleton; on the other hand, to achieve uniform dispersion of functional fillers, additives, etc. in the entire coating system in the skeleton; the two work together to obtain an inorganic protective coating with excellent performance.

[0027] In the present application, the first dispersion system is used to modify the charge of the main filler, and the second dispersion system utilizes steric hindrance to adjust the dispersibility of the overall system. In order to reduce the impact of the second dispersed system on the charge distribution of the main filler during use, the present application adds phospholipid-polyethylene glycol to the second dispersed system. Phospholipid-polyethylene glycol is an amphiphilic molecule whose hydrophobic end (phospholipid part) can be strongly adsorbed on the surface of the nanoparticles, but its adsorption site does not overlap with the charge site and will not shield the charge; the hydrophilic end (polyethylene glycol chain) extends into the base material. This preferential adsorption behavior enables phospholipid-polyethylene glycol to occupy key positions on the particle surface, thereby reducing the adsorption of PVP and reducing the coverage of PVP on the surface charge of the particles. By reducing the adsorption of PVP, phospholipid-polyethylene glycol can protect the charge distribution given to the particles by the first dispersant and maintain the effectiveness of electrostatic repulsion and attraction; the polyethylene glycol chain of phospholipid-polyethylene glycol forms a thick molecular layer around the particles, producing a steric hindrance effect. This effect works synergistically with the steric hindrance effect of PVP. While protecting the charge distribution, it will not reduce the dispersing effect of the second dispersed system.

[0028] In the entire coating system, if the particles are dispersed too evenly, the distance between the particles is too large, resulting in poor filling and the inability to form a dense structure. If the particles are packed too closely, the interactions between the particles are enhanced, which easily leads to agglomeration, reduced coating uniformity, and inconsistent local performance. Therefore, this application uses a double dispersion system to balance the relationship between the two, improving the overall performance of the coating.

[0029] Furthermore, the aminosilane coupling agent is KH-550 silane coupling agent, the epoxysilane coupling agent is KH-560 silane coupling agent, the anionic surfactant is sodium lauryl sulfate, and the cationic surfactant is hexadecyltrimethylammonium bromide.

[0030] Furthermore, the mass ratio of the aminosilane coupling agent to the anionic surfactant in composition A is 1:0.8-1.3; the mass ratio of the epoxysilane coupling agent to the cationic surfactant in composition B is 1:1-1.2.

[0031] Under acidic conditions, the aminosilane coupling agent makes the surface of the nano-silicon particles have a positive charge, and then combines with the anionic surfactant through the charge effect, so that the final particle surface has a negative charge; under alkaline conditions, the epoxysilane coupling agent makes the surface of the nano-silicon particles have a negative charge, and then combines with the cationic surfactant through the charge effect, so that the final particle surface has a positive charge. The silane coupling agent and the ionic surfactant jointly perform charge modification on the particle surface, which can form a stable double-layer structure on the nano-silicon surface with high charge stability. The charge characteristics imparted by the silane coupling agent are highly dependent on pH. When the pH changes, the charge on the particle surface may be reversed or neutralized, resulting in instability of the dispersed system; the ionic surfactant mainly attaches to the particle surface through physical adsorption, and this adsorption effect is weak and easy to desorb; therefore, the present application uses the two together. The synergistic effect of the silane coupling agent and the ionic surfactant can maintain the stability of the dispersed system under different pH conditions, and after being treated with the silane coupling agent, the ionic surfactant and the particles are adsorbed firmly through charge adsorption, which helps to maintain charge stability.

[0032] Furthermore, the addition amount of the component A and the component B is respectively 20-25% of the mass of the corresponding processed graded nano-silicon; and the addition amount of the second dispersed system is 8-10% of the total mass of the main filler.

[0033] Furthermore, the functional filler includes at least one of nano titanium dioxide, nano silicon carbide, nano aluminum oxide, nano rare earth oxide, heavy calcium powder, and talc.

[0034] Furthermore, the mass ratio of the PVP dispersant to the phospholipid-polyethylene glycol in the second dispersion system is 2-3:1.

[0035] Furthermore, the coating base material is nano-silica sol modified by a silane coupling agent.

[0036] The method for preparing the protective nano hard coating comprises the following steps:

[0037] S1, preparing a sol, wherein the sol is a coating base material;

[0038] S2. Preparation of nano-solution:

[0039] S2.2. Preparation of 15-20 nm nano-silicon: Using tetraethyl orthosilicate as the main raw material, 15-20 nm nano-silicon particles were prepared by sol-gel process;

[0040] S2.3, Preparation of 25-50nm nano-silicon: Using high-purity silane gas with a purity of ≥99.9% as the main raw material, adopt the vapor phase deposition method to prepare 25-50nm nano-silicon particles at 400-450℃

[0041] S2.4. Preparation of 55-80 nm nano-silicon: Using sodium silicate as the main raw material, 55-80 nm nano-silicon particles were prepared by a hydrothermal method;

[0042] S2.5. Dispersing 15-20 nm nano-silicon, 25-50 nm nano-silicon, and 55-80 nm nano-silicon in deionized water to form suspensions; then using component A and component B in the first dispersion system to dissolve the 15-20 nm nano-silicon and the 55-80 nm nano-silicon with the same charge, and dissolving the 25-50 nm nano-silicon with a different charge;

[0043] S2.6. The 15-20 nm nano-silicon suspension, the 25-50 nm nano-silicon suspension, and the 55-80 nm nano-silicon suspension respectively treated by the first dispersion system are uniformly mixed to obtain a nano-silicon suspension. The functional filler and the second dispersion system are added to the nano-silicon suspension, and the mixture is stirred at 300-380 rpm for 10-15 minutes to obtain a nano-solution.

[0044] S3. Add the nano solution to the sol at a stirring speed of 420-450 r / min, stir for 20-30 minutes, then reduce the stirring speed to 350-400 r / min, add the additive while stirring, continue stirring for 30-35 minutes, and then let it stand to obtain the target coating.

[0045] The present invention combines the sol-gel method, vapor deposition method and hydrothermal method composite process, and achieves comprehensive improvement of the coating's mechanical properties, long-term weather resistance, corrosion resistance, self-cleaning properties and environmental adaptability through the synergistic effect of 15-80nm multi-scale nano-silicon particles.

[0046] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0047] 1. The protective nano-hard coating of the present invention utilizes particles of three different size ranges for effective grading. Particles of different sizes fill each other to form a dense coating with excellent performance. Based on this, a small amount of functional filler can be used to enhance specific properties according to different usage environments and applications.

[0048] 2. The main filler in the present invention relies on charge modification to achieve uniform dispersion and sufficient filling, utilizing charge modification and gradation to form a continuous and stable mechanical skeleton;

[0049] 3. The entire inorganic coating system of the present invention uses a double dispersion system, and the two work synergistically to balance the uniformity and density of the overall coating, thereby obtaining a protective inorganic coating with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] 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 embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort, among which:

[0051] Figure 1 is a sample detection diagram within the scope of Example 2 of the present invention;

[0052] Figure 2 yes Figure 1 The enlarged view of the product after the pencil hardness test;

[0053] Figure 3 This is a graph showing the mildew resistance grade test results of a sample within the scope of Example 2 of the present invention;

[0054] Figure 4 This is a graph showing the antibacterial test results of a sample within the scope of Example 2 of the present invention. DETAILED DESCRIPTION

[0055] In order to make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present invention and are not intended to limit the present invention. That is, the embodiments described herein are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein may be arranged and designed in various different configurations.

[0056] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely intended to represent selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0057] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0058] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0059] Example 1

[0060] A preferred embodiment of the present invention provides a protective nano hard coating, comprising a coating base, a nano inorganic filler, and an additive, wherein the nano inorganic filler comprises a main filler and a functional filler, wherein the functional filler is added in an amount of 5% of the total mass of the nano inorganic filler, and the remainder of the nano inorganic filler is the main filler;

[0061] Based on the total mass of the main filler, the main filler is composed of the following components by mass fraction: 15w% of 15-20nm nano-silicon, 45w% of 25-50nm nano-silicon, and 40w% of 55-80nm nano-silicon;

[0062] Wherein, the particle size range of the functional filler is 20-50 nm.

[0063] Preferably, the 15-20 nm nano-silicon and the 55-80 nm nano-silicon have positive charges, and the 25-50 nm nano-silicon has negative charges.

[0064] The auxiliary agent includes a double dispersion system, and the double dispersion system includes a first dispersion system and a second dispersion system;

[0065] The first dispersion system includes composition A and composition B, wherein composition A includes the following components: an aminosilane coupling agent and an anionic surfactant, wherein the aminosilane coupling agent and the anionic surfactant are combined to make the surface of the nano-silicon have a negative charge; and composition B includes the following components: an epoxy silane coupling agent and a cationic surfactant, wherein the epoxy silane coupling agent and the cationic surfactant are combined to make the surface of the nano-silicon have a positive charge.

[0066] The second dispersion system includes PVP dispersant and phospholipid-polyethylene glycol.

[0067] The method for using component A is as follows: disperse nano-silicon in deionized water, add aminosilane coupling agent, adjust the pH to 5-6, react at 60-70°C with stirring for 2-3 hours, then add anionic surfactant and stir evenly, cool to room temperature and then ultrasonically disperse for 30 minutes to obtain nano-silicon with negative surface charge;

[0068] The method of using component B is as follows: disperse nano-silicon in deionized water, add epoxy silane coupling agent, adjust the pH to 8-9, stir and react at 60-70°C for 2-3 hours, then add cationic surfactant, stir evenly and cool to room temperature, and ultrasonically disperse for 30 minutes to obtain nano-silicon with positive charge on the surface.

[0069] The aminosilane coupling agent is KH-550 silane coupling agent, the epoxysilane coupling agent is KH-560 silane coupling agent, the anionic surfactant is sodium lauryl sulfate, and the cationic surfactant is hexadecyltrimethylammonium bromide;

[0070] The mass ratio of the aminosilane coupling agent to the anionic surfactant in composition A is 1:0.8-1.3; the mass ratio of the epoxysilane coupling agent to the cationic surfactant in composition B is 1:1-1.2;

[0071] The added amount of component A and component B is respectively 20-25% of the mass of the corresponding processed graded nano-silicon; the added amount of the second dispersed system is 8-10% of the total mass of the main filler.

[0072] The functional filler comprises nano titanium dioxide, nano silicon carbide, nano aluminum oxide and nano rare earth oxide, and the mass ratio of the nano titanium dioxide, nano silicon carbide, nano aluminum oxide and nano rare earth oxide is 2:1:1:1.

[0073] The mass ratio of the PVP dispersant to phospholipid-polyethylene glycol in the second dispersion system is 2-3:1.

[0074] The coating base material is nano-silica sol modified by a silane coupling agent, the silane coupling agent is γ-methacryloxypropyltrimethoxysilane, and the nano-silica sol is prepared with tetraethyl orthosilicate as the main raw material by referring to the existing preparation method of nano-silica sol.

[0075] The method for preparing the protective nano hard coating comprises the following steps:

[0076] S1, preparing a sol, wherein the sol is a coating base material;

[0077] S2. Preparation of nano-solution:

[0078] S2.2. Preparation of 15-20 nm nano-silicon: Using tetraethyl orthosilicate as the main raw material, 15-20 nm nano-silicon particles were prepared by sol-gel process;

[0079] S2.3. Preparation of 25-50 nm nano-silicon: Using high-purity silane gas with a purity of ≥99.9% as the main raw material, a vapor phase deposition method is used to prepare 25-50 nm nano-silicon particles at 400-450°C.

[0080] S2.4. Preparation of 55-80 nm nano-silicon: Using sodium silicate as the main raw material, 55-80 nm nano-silicon particles were prepared by a hydrothermal method;

[0081] S2.5. Dispersing 15-20 nm nano-silicon, 25-50 nm nano-silicon, and 55-80 nm nano-silicon in deionized water to form suspensions; then using component A and component B in the first dispersion system to dissolve the 15-20 nm nano-silicon and the 55-80 nm nano-silicon with the same charge, and dissolving the 25-50 nm nano-silicon with a different charge;

[0082] S2.6. The 15-20 nm nano-silicon suspension, the 25-50 nm nano-silicon suspension, and the 55-80 nm nano-silicon suspension respectively treated by the first dispersion system are uniformly mixed to obtain a nano-silicon suspension. The functional filler and the second dispersion system are added to the nano-silicon suspension, and the mixture is stirred at 300-380 rpm for 10-15 minutes to obtain a nano-solution.

[0083] S3. Add the nano solution to the sol at a stirring speed of 420-450 r / min, stir for 20-30 minutes, then reduce the stirring speed to 350-400 r / min, add the additive while stirring, continue stirring for 30-35 minutes, and then let it stand to obtain the target coating.

[0084] Example 2

[0085] This embodiment is based on the embodiment 1, but differs from the embodiment 1 in that, based on the total mass of the main filler, the main filler is composed of the following components by mass fraction: 20w% of 15-20nm nano-silicon, 40w% of 25-50nm nano-silicon, and 40w% of 55-80nm nano-silicon.

[0086] According to the test method of GB / T 1728-2020 surface drying method B and through drying method A, the surface drying time of the coating of this embodiment can reach within 15 minutes, and the through drying time can reach within 7 hours;

[0087] According to HG / T 3950-2007 Antimicrobial Coatings: Appendix B Antimicrobial Coatings - Antifungal Performance Test Method, the antifungal grade test report results of a sample within the scope of Example 2 are as follows: Figure 3 As shown;

[0088] According to HG / T 3950-2007 Antibacterial Coatings: Appendix A Antibacterial Coatings - Antibacterial Performance Test Method, the antibacterial test report results of a sample within the scope of Example 2 are as follows: Figure 4 shown.

[0089] Example 3

[0090] This embodiment is based on the embodiment 1, but differs from the embodiment 1 in that, based on the total mass of the main filler, the main filler is composed of the following components by mass fraction: 25w% of 15-20nm nano-silicon, 45w% of 25-50nm nano-silicon, and 30w% of 55-80nm nano-silicon.

[0091] Example 4

[0092] This embodiment is based on the embodiment 2, but differs from the embodiment 2 in that the amount of the functional filler added is 1% of the total mass of the nano inorganic filler.

[0093] Example 5

[0094] This embodiment is based on the embodiment 2, but differs from the embodiment 2 in that the amount of the functional filler added is 8% of the total mass of the nano inorganic filler.

[0095] Comparative Example 1

[0096] This embodiment is based on Example 2, but differs from Example 2 in that the mass ratio of the aminosilane coupling agent to the anionic surfactant in composition A is 1:0.7; the mass ratio of the epoxysilane coupling agent to the cationic surfactant in composition B is 1:0.9.

[0097] Comparative Example 2

[0098] This embodiment is based on Example 2, but differs from Example 2 in that the mass ratio of the aminosilane coupling agent to the anionic surfactant in composition A is 1:1.4; the mass ratio of the epoxysilane coupling agent to the cationic surfactant in composition B is 1:1.2.

[0099] Comparative Example 3

[0100] This embodiment is based on Example 2, but differs from Example 2 in that the mass ratio of the PVP dispersant to the phospholipid-polyethylene glycol in the second dispersion system is 1:1.

[0101] Comparative Example 4

[0102] This embodiment is based on Example 2, but differs from Example 2 in that the mass ratio of the PVP dispersant to the phospholipid-polyethylene glycol in the second dispersion system is 4:1.

[0103] Comparative Example 5

[0104] This embodiment is based on the embodiment 2, but differs from the embodiment 2 in that the added amounts of the components A and B are 18% of the mass of the corresponding processed graded nano-silicon.

[0105] Comparative Example 6

[0106] This embodiment is based on the embodiment 2, but differs from the embodiment 2 in that the added amounts of the components A and B are 26% of the mass of the corresponding processed graded nano-silicon.

[0107] Comparative Example 7

[0108] This embodiment is based on the embodiment 2, but differs from the embodiment 2 in that the amount of the second dispersion system added is 7% of the total mass of the main filler.

[0109] Comparative Example 8

[0110] This embodiment is based on the embodiment 2, but differs from the embodiment 2 in that the amount of the second dispersion system added is 11% of the total mass of the main filler.

[0111] Comparative Example 9

[0112] This embodiment is based on the embodiment 2, but differs from the embodiment 2 in that the main filler does not contain 15-20 nm nano-silicon, but is composed of 50 w % of 25-50 nm nano-silicon and 50 w % of 55-80 nm nano-silicon.

[0113] Comparative Example 10

[0114] This embodiment is based on the embodiment 2, but differs from the embodiment 2 in that the main filler does not contain 25-50 nm nano-silicon, but is composed of 40 w % of 15-20 nm nano-silicon and 60 w % of 55-80 nm nano-silicon.

[0115] Comparative Example 11

[0116] This embodiment is based on the embodiment 2, but differs from the embodiment 2 in that the main filler does not contain 55-80 nm nano-silicon, but is composed of 40 w % of 15-20 nm nano-silicon and 60 w % of 25-50 nm nano-silicon.

[0117] Comparative Example 12

[0118] This embodiment is based on the embodiment 2, but differs from the embodiment 2 in that the main filler is entirely composed of nano-silicon with the same charge and having a size larger than 80 nm and smaller than 100 nm, and component A or component B is used to perform charge modification on the nano-silicon.

[0119] Comparative Example 13

[0120] This embodiment is based on the embodiment 2, but differs from the embodiment 2 in that: the main filler is entirely composed of nano-silicon with the same charge and less than 15 nm; component A or component B is used to perform charge modification on the nano-silicon; the nano-silicon cannot be dispersed, and visible agglomeration occurs.

[0121] Test Example 1

[0122] The coatings prepared in Examples 1-5 and Comparative Examples 1-13 were tested for zeta potential using a conventional zeta potential tester. The coatings were then left to stand at room temperature for 24 hours to observe whether any visible precipitation, agglomeration, or delamination occurred. The test results are shown in Table 1. A zeta potential absolute value greater than 30 mV indicates that the coating is stable.

[0123] Table 1 Coating stability test

[0124] Zeta potential absolute value stability Example 1 >30mV No precipitation, agglomeration or stratification Example 2 >30mV No precipitation, agglomeration or stratification Example 3 >30mV No precipitation, agglomeration or stratification Example 4 >30mV No precipitation, agglomeration or stratification Example 5 >30mV No precipitation, agglomeration or stratification Comparative Example 1 <30mV Precipitation, agglomeration, and stratification occur Comparative Example 2 <30mV Precipitation, agglomeration, and stratification occur Comparative Example 3 <30mV Precipitation, agglomeration, and stratification occur Comparative Example 4 <30mV Precipitation, agglomeration, and stratification occur Comparative Example 5 <30mV Precipitation, agglomeration, and stratification occur Comparative Example 6 >30mV No precipitation, agglomeration or stratification Comparative Example 7 <30mV Agglomeration occurs Comparative Example 8 >30mV No precipitation, agglomeration or stratification Comparative Example 9 >30mV No precipitation, agglomeration or stratification Comparative Example 10 <30mV Precipitation occurs Comparative Example 11 <30mV Agglomeration occurs Comparative Example 12 <30mV Precipitation occurs Comparative Example 13 <30mV Agglomeration occurs

[0125] As shown in Table 1, the amount of dispersant added and the gradation between particles in this application will significantly affect the stability of the coating.

[0126] Test Example 2

[0127] The coatings prepared in Examples 1-5 and Comparative Examples 1-13 were tested for mechanical properties. The results are shown in Table 2. The testing method includes the following:

[0128] 1. Pencil hardness test

[0129] Refer to GB / T 6739. Apply the coating evenly on a substrate (such as glass, metal, or plastic plate) and allow it to dry and solidify. The coating thickness is 50 μm. Insert a pencil into a pencil hardness tester. Fix the pencil at a 45° angle to the coating surface and push the pencil across the coating surface with uniform force. The scratch length is approximately 6.5 mm. Start with a low-hardness pencil (6B) and gradually increase the hardness until the highest hardness is found that does not scratch the coating.

[0130] The sample picture of a product before testing under the scope of Example 2 of the present invention is as follows Figure 1 As shown, the sample after detection is partially enlarged as shown in Figure 2 As shown, the pencil hardness of the product shown in Example 2 can reach 7H;

[0131] 2. Wear weight loss test

[0132] A taber abrasion tester (existing technology) was used with the following test parameters: load 500 g, rotation speed 60 rpm, test number 1000. The instrument was started and the coating was subjected to a wear test. The wear weight loss was calculated as: ΔW = W1 - W2, where W1 is the initial mass of the sample and W2 is the mass after wear.

[0133] 3. Weather resistance test

[0134] Use a xenon lamp aging test chamber for testing (existing technology). The coating is evenly coated on a substrate (such as a metal plate or a plastic plate), dried and cured to obtain a coating sample with a thickness of 50 μm. Set the parameters of the xenon lamp aging test chamber: Light intensity: 0.55 W / m 2 @340nm; Blackboard temperature: 65°C; Relative humidity: 50%; Water spray cycle: 18 minutes of water spraying / 102 minutes of drying; Set the test time to 10,000 hours; Place the sample in the aging test chamber and start the test; After 10,000 hours of xenon lamp aging test, record any changes in the coating's appearance (such as discoloration, chalking, cracking, etc.); No changes indicate good weather resistance.

[0135] 4. Self-cleaning test

[0136] Refer to ASTM D5946 standard and use a contact angle meter to measure the water contact angle of the coating;

[0137] 5. Washability test

[0138] Referring to standard GB / T 9266, the sample was mounted on a scrubbing tester equipped with a black pig bristle brush. The test parameters were as follows: rinsing medium: 0.5% (m / m) laundry detergent (pH 9.5-11.0); load: (450±10)g; speed: (37±2) rpm; scrubbing cycle: 200,000 cycles. The product within the scope of Example 2 showed no visible substrate exposure after 200,000 scrubbing cycles.

[0139] Table 2 Test results of coating mechanical properties

[0140]

[0141]

[0142] Combining the data in Tables 1 and 2, it can be seen that Example 2 of the present invention is the optimal solution. The present invention has excellent weather resistance, hardness, erosion resistance, and wear resistance. Moreover, the present invention uses inorganic components as the main ingredients, which has the advantage of low volatile organic compound (VOC) emissions. The present invention can be used in protective engineering of concrete and other materials in a variety of fields, such as water conservancy, transportation, construction, automobiles, energy, and marine engineering.

[0143] Test Example 3

[0144] The surface properties and adhesion of the coatings obtained in Examples 1-5 of the present invention were tested. The test results are shown in Table 3.

[0145] Adhesion test: Adhesion test was performed on the coatings of Examples 1 to 5 of the present invention using the test method of standard GB / T 9286-2021. According to GB / T 9286-2021, the adhesion grade is: grade 0 is the best and grade 5 is the worst.

[0146] Water resistance test: The test method adopts GB / T22374-2018 Section 6.3.12 & GB / T 9274-1988 Method C, and the coatings of Examples 1-5 of the present invention are tested for water resistance. Deionized water, drip method, (23±2)°C, 168h, observe whether there is any visible change after 168h. If no visible change occurs, it indicates good water resistance.

[0147] Oil resistance test: The test method adopts GB / T 22374-2018 Section 6.3.13.3 & GB / T9274-1988 Method C, and the coatings of Examples 1-5 of the present invention are tested for oil resistance, 120# solvent oil, drip method, (23±2)℃, 72h, and observe whether there is any visible change after 72h. If no visible change occurs, it indicates good oil resistance.

[0148] Table 3 Surface performance and adhesion test results of coatings

[0149]

[0150] The coatings prepared within the scope of Examples 1-5 of the present invention have good adhesion and good water resistance and oil resistance.

[0151] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions and improvements made by any technician familiar with the field within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A protective nano hard coating, comprising a coating base material, a nano inorganic filler, and an additive, characterized in that: The nano inorganic filler includes a main filler and a functional filler, wherein the amount of the functional filler added is 1-8% of the total mass of the nano inorganic filler, and the balance of the nano inorganic filler is the main filler; Based on the total mass of the main filler, the main filler is composed of the following components by mass fraction: 15w% to 25w% of 15-20nm nano-silicon, 35w% to 45w% of 25-50nm nano-silicon, and 30w% to 40w% of 55-80nm nano-silicon; Wherein, the particle size range of the functional filler is 20-50nm; The coating base material is nano-silica sol modified by a silane coupling agent; The auxiliary agent includes a double dispersion system, and the double dispersion system includes a first dispersion system and a second dispersion system; The first dispersion system includes composition A and composition B, wherein composition A includes the following components: an aminosilane coupling agent and an anionic surfactant, wherein the aminosilane coupling agent and the anionic surfactant are combined to make the surface of the nano-silicon have a negative charge; and composition B includes the following components: an epoxy silane coupling agent and a cationic surfactant, wherein the epoxy silane coupling agent and the cationic surfactant are combined to make the surface of the nano-silicon have a positive charge. The second dispersion system includes PVP dispersant and phospholipid-polyethylene glycol; Component A and component B in the first dispersed system are used to ensure that nano-silicon with a size of 15-20 nm and nano-silicon with a size of 55-80 nm have the same charge, and nano-silicon with a size of 25-50 nm has a different charge.

2. The protective nano hard coating according to claim 1, characterized in that: The aminosilane coupling agent is KH-550 silane coupling agent, the epoxysilane coupling agent is KH-560 silane coupling agent, the anionic surfactant is sodium lauryl sulfate, and the cationic surfactant is hexadecyltrimethylammonium bromide.

3. The protective nano hard coating according to claim 1, characterized in that: The mass ratio of the aminosilane coupling agent to the anionic surfactant in composition A is 1:0.8-1.3; the mass ratio of the epoxysilane coupling agent to the cationic surfactant in composition B is 1:1-1.

2.

4. The protective nano hard coating according to claim 1, characterized in that: The addition amount of the component A and the component B is respectively 20-25% of the mass of the corresponding processed graded nano-silicon; the addition amount of the second dispersed system is 8-10% of the total mass of the main filler.

5. The protective nano hard coating according to claim 1, characterized in that: The functional filler includes at least one of nano titanium dioxide, nano silicon carbide, nano aluminum oxide, nano rare earth oxide, heavy calcium powder and talc powder.

6. The protective nano hard coating according to claim 4, characterized in that: The mass ratio of the PVP dispersant to phospholipid-polyethylene glycol in the second dispersion system is 2-3:

1.

7. The method for preparing a protective nano hard coating according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, preparing a sol, wherein the sol is a coating base material; S2. Preparation of nano-solution: S2.

2. Preparation of 15-20 nm nano-silicon: Using tetraethyl orthosilicate as the main raw material, 15-20 nm nano-silicon particles were prepared by sol-gel process; S2.

3. Preparation of 25-50 nm nano-silicon: Using high-purity silane gas with a purity of ≥99.9% as the main raw material, 25-50 nm nano-silicon particles are prepared by vapor deposition at 400-450°C. S2.

4. Preparation of 55-80 nm nano-silicon: Using sodium silicate as the main raw material, 55-80 nm nano-silicon particles were prepared by a hydrothermal method; S2.

5. Dispersing 15-20 nm nano-silicon, 25-50 nm nano-silicon, and 55-80 nm nano-silicon in deionized water to form suspensions, respectively. Then, using component A and component B in the first dispersion system, respectively, the 15-20 nm nano-silicon and the 55-80 nm nano-silicon have the same charge, and the 25-50 nm nano-silicon has a different charge. S2.

6. The 15-20 nm nano-silicon suspension, the 25-50 nm nano-silicon suspension, and the 55-80 nm nano-silicon suspension respectively treated by the first dispersion system are uniformly mixed to obtain a nano-silicon suspension. The functional filler and the second dispersion system are added to the nano-silicon suspension, and the mixture is stirred at 300-380 r / min for 10-15 minutes to obtain a nano-solution. S3. Add the nano solution to the sol at a stirring speed of 420-450 r / min, stir for 20-30 minutes, then reduce the stirring speed to 350-400 r / min, add the additive while stirring, continue stirring for 30-35 minutes, and then let it stand to obtain the target coating.

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