Protective nano hard coating and preparation method thereof

Abstract

The invention discloses a protective nano hard coating and a preparation method thereof, and belongs to the field of inorganic coatings, the protective nano hard coating comprises a coating base material, a nano inorganic filler and an auxiliary agent, and is characterized in that the nano inorganic filler comprises a main filler and a functional filler, the addition amount of the functional filler is 1-8% of the total mass of the nano inorganic filler, and the addition amount of the auxiliary agent is 1-8% of the total mass of the main filler. The balance of the nano inorganic filler is the main filler; by taking the total mass of the main filler as a standard, the main filler is prepared from the following components in percentage by mass: 15 to 25 percent of nano silicon with the particle size of 15 to 20 nm, 35 to 45 percent of nano silicon with the particle size of 25 to 50 nm and 30 to 40 percent of nano silicon with the particle size of 55 to 80 nm; wherein the particle size range of the functional filler is 20-50 nm. Particles in three particle size ranges are effectively graded, the particles with different particle sizes are mutually filled to form a compact coating, the coating is excellent in performance, and on the basis, certain performance can be emphatically enhanced through a small amount of functional filler 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 made with nanotechnology. The particles of nano-coating are very small and can penetrate into the tiny gaps on the surface of the material to provide 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 more on a narrow range and have a single particle size distribution, usually <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, 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 the current traditional nano silicon coatings are mostly focused on small particle coatings in a narrow range of <50nm, and are not suitable for complex environments such as high impact, high corrosion, and frequent erosion due to the small nano particles with a single gradation cannot form a continuous and stable mechanical skeleton structure.

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

[0006] A protective nano hard coating, comprising a coating base material, a nano inorganic filler, and an additive, wherein the nano inorganic filler comprises 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 remainder of the nano inorganic filler is the main filler;

[0007] Taking the total mass of the main filler as the standard, 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 20-50nm.

[0009] Based on the advantages of nano-scale small-particle inorganic coatings, the present invention expands the grading range through the grading 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 grading 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 formula, and the particle size range and the addition ratio have no linear relationship in the effect on the grading. For example, increasing the proportion of small particles may increase the reaction activity of the coating, but at the same time it may also increase the tendency to agglomerate and affect the uniformity of the coating.

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

[0012] 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 fillers can be used to enhance certain performance according to different use environments and application objects. The functional fillers are added within the particle size range of 20-50nm and will not destroy the mechanical skeleton formed by the main fillers.

[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, the present application will preferably use nano silicon as the main component of the protective inorganic coating of the present application. The main filler of the present 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 nano-scale particles have a small particle size 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 the particles, it can also ensure the mutual filling of particles of different 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 in which large and small particles carry the same charge and medium particles carry 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 the present application, large particles carry the same charge, and the repulsion of like charges is utilized to avoid 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, large particles have a large particle size. If the large particles are piled together, small and medium particles are blocked from entering the pores inside them, a dense coating cannot be formed, and the mechanical properties are unevenly distributed.

[0019] In the present 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 particles and the 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, which will cause a large distance between them. Although the small particles will be attracted, it is difficult for them to completely fill the gaps 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, which will form 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] The present application utilizes a double dispersion system to achieve charge modification of the main filler particles on the one hand, thereby preparing a uniformly distributed and dense mechanical skeleton; on the other hand, it achieves 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 dispersed system is used to modify the charge of the main filler, and the second dispersed system uses 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 when in 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 nanoparticles, but its adsorption site does not overlap with the charge site and will not shield the charge; while 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 surface of the particles, 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 of the particles given 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, which 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] For the entire coating system, if the particles are dispersed too evenly, the distance between the particles is too large, resulting in poor filling effect and failure to form a dense structure; if the particles are packed too closely, the interaction between the particles is enhanced, agglomeration is likely to occur, the uniformity of the coating is reduced, and the local performance is inconsistent. Therefore, this application uses a double dispersion system to balance the relationship between the two and improve 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 dodecyl 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 carry a positive charge, and then combines with the anionic surfactant through the charge effect, so that the final particle surface carries a negative charge; under alkaline conditions, the epoxysilane coupling agent makes the surface of the nano-silicon particles carry a negative charge, and then combines with the cationic surfactant through the charge effect, so that the final particle surface carries a positive charge. The silane coupling agent and the ionic surfactant jointly carry out charge modification on the particle surface, and a stable double electric layer structure with high charge stability can be formed on the surface of the nano-silicon. The charge characteristics given by the silane coupling agent are highly dependent on pH. When the pH changes, the charge on the surface of the particles may be reversed or neutralized, resulting in instability of the dispersed system; the ionic surfactant is mainly attached to the particle surface by physical adsorption, and this adsorption is weak and easy to desorb; therefore, the present application combines the two together for use, and 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 by charge, and the adsorption is firm, which helps to maintain charge stability.

[0032] Furthermore, the added amounts of component A and component B are 20-25% of the mass of the corresponding processed graded nano-silicon respectively; and the added 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 talcum powder.

[0034] Furthermore, the mass ratio of PVP dispersant to phospholipid-polyethylene glycol in the second dispersed 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 sol, wherein the sol is a coating base material;

[0038] S2. Preparation of nano solution:

[0039] S2.2, preparation of 15-20nm nano-silicon: using tetraethyl orthosilicate as the main raw material, using sol-gel process to prepare 15-20nm nano-silicon particles;

[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, the vapor phase deposition method is used to prepare 25-50nm nano-silicon particles at 400-450℃

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

[0042] S2.5, respectively dispersing 15-20 nm nano-silicon, 25-50 nm nano-silicon, and 55-80 nm nano-silicon in deionized water to form a suspension; then using component A and component B in the first dispersion system accordingly so that 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;

[0043] S2.6, uniformly mix the 15-20nm nano-silicon suspension, 25-50nm nano-silicon suspension, and 55-80nm nano-silicon suspension respectively treated by the first dispersion system to obtain a nano-silicon suspension, add a functional filler and a second dispersion system to the nano-silicon suspension, mix and stir at 300-380r / min 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 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 mechanical properties, long-term weather resistance, corrosion resistance, self-cleaning property and environmental adaptability of the coating 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. A protective nano hard coating of the present invention uses particles of three particle size ranges for effective grading, and particles of different particle sizes are filled with each other to form a dense coating with excellent performance. On this basis, a small amount of functional fillers can be used to enhance certain performance according to different use environments and application objects;

[0048] 2. The main filler in the present invention relies on charge modification to achieve uniform dispersion and full filling, and utilizes charge modification and grading 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 entire 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 regarded as limiting the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative work, 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 partial view of the product shown after the pencil hardness test;

[0053] Figure 3 This is a graph showing the test results of the mildew resistance level of a certain 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 purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings herein can 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 claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making 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 such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

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

[0059] Example 1

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

[0061] Taking the total mass of the main filler as the standard, 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 20-50nm.

[0063] Preferably, the 15-20 nm nano-silicon and the 55-80 nm nano-silicon carry positive charges, and the 25-50 nm nano-silicon carries 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 of using component A is as follows: disperse nano silicon in deionized water, add aminosilane coupling agent, adjust pH to 5-6, stir and react at 60-70°C for 2-3 hours, add anionic surfactant and stir evenly, cool to room temperature and disperse by ultrasonic for 30 minutes to obtain nano silicon with negative charge on the surface;

[0068] The method of using component B is as follows: disperse nano silicon in deionized water, add epoxy silane coupling agent, adjust 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 dodecyl 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 amounts of component A and component B are 20-25% of the mass of the corresponding processed graded nano-silicon respectively; 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 PVP dispersant to phospholipid-polyethylene glycol in the second dispersed 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 sol, wherein the sol is a coating base material;

[0077] S2. Preparation of nano solution:

[0078] S2.2, preparation of 15-20nm nano-silicon: using tetraethyl orthosilicate as the main raw material, using sol-gel process to prepare 15-20nm nano-silicon particles;

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

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

[0081] S2.5, respectively dispersing 15-20 nm nano-silicon, 25-50 nm nano-silicon, and 55-80 nm nano-silicon in deionized water to form a suspension; then using component A and component B in the first dispersion system accordingly so that 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;

[0082] S2.6, uniformly mix the 15-20nm nano-silicon suspension, 25-50nm nano-silicon suspension, and 55-80nm nano-silicon suspension respectively treated by the first dispersion system to obtain a nano-silicon suspension, add a functional filler and a second dispersion system to the nano-silicon suspension, mix and stir at 300-380r / min 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 stand to obtain the target coating.

[0084] Example 2

[0085] This embodiment is based on the embodiment 1, but is different 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 actual drying method A, the surface drying time of the coating of this embodiment can reach within 15 minutes, and the actual 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 result of a sample within the scope of Example 2 is as follows: Figure 3 As shown;

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

[0089] Example 3

[0090] This embodiment is based on the embodiment 1, but is different 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 is different 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 is different 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 Embodiment 2, but differs from Embodiment 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 Embodiment 2, but differs from Embodiment 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 the embodiment 2, but is different from the embodiment 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 the embodiment 2, but is different from the embodiment 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 is different from the embodiment 2 in that the added amounts of the component A and the component B are 18% of the mass of the nano-silicon of the corresponding processing grade.

[0105] Comparative Example 6

[0106] This embodiment is based on the embodiment 2, but is different from the embodiment 2 in that the added amounts of the component A and the component B are 26% of the mass of the nano-silicon of the corresponding processing grade.

[0107] Comparative Example 7

[0108] This embodiment is based on the embodiment 2, but is different from the embodiment 2 in that the amount of the second dispersed 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 is different from the embodiment 2 in that the amount of the second dispersed 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 is different 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 is different 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 is different 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 is different from the embodiment 2 in that the main filler is entirely composed of nano-silicon with the same charge and having a size greater than 80 nm and less 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 is different 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 subjected to Zeta potential testing using an existing Zeta potential tester, and the stability of the coatings was observed. After standing at room temperature for 24 hours, it was observed whether there was obvious precipitation, agglomeration or stratification visible to the naked eye. The test results are shown in Table 1. The absolute value of the Zeta potential 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 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 Comparative Example 12 <30mV Precipitation occurs Comparative Example 13 <30mV Agglomeration

[0125] As can be seen from the data 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 the substrate (such as glass, metal or plastic plate), dry and solidify, the coating thickness is 50μm, insert the pencil into the pencil hardness tester, fix the pencil at a 45° angle to the coating surface, push the pencil on the coating surface with uniform force, the scratch length is about 6.5mm, start with a low hardness pencil (6B), and gradually increase the hardness until the highest hardness that does not scratch the coating is found;

[0130] A sample of a product before testing under the scope of Example 2 of the present invention is shown in FIG. 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 this embodiment 2 can reach 7H;

[0131] 2. Wear weight loss test

[0132] Use a taber abrasion tester (existing technology), set the test parameters: load 500g, rotation speed 60rpm, test number 1000, start the instrument, and perform a wear test on the coating; calculate the wear weight loss: ΔW = W1-W2, 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), evenly apply the coating on a substrate (such as a metal plate or a plastic plate), dry and solidify, and 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℃; Relative humidity: 50%; Water spraying cycle: 18 minutes water spraying / 102 minutes drying; Set test time: 10,000 hours; Put the sample into the aging test chamber and start the test; After 10,000 hours of xenon lamp aging test, record the changes in the coating appearance (such as discoloration, chalking, cracking, etc.), no change indicates that the coating has good weather resistance;

[0135] 4. Self-cleaning test

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

[0137] 5. Washability test

[0138] With reference to standard GB / T 9266, the sample was fixed on a scrubbing test machine, a black pig brown brush was installed, and the test parameters were set as follows: rinsing medium: 0.5% (m / m) washing powder liquid (pH 9.5-11.0); load: (450±10) g; speed: (37±2) revolutions per minute; scrubbing times: 200,000 times. After 200,000 times of scrubbing, no visible substrate was exposed in the product within the scope of Example 2 of the present invention.

[0139] Table 2 Coating mechanical properties test results

[0140]

[0141]

[0142] Combining the data in Table 1 and Table 2, it can be seen that Example 2 of the present invention is the best solution. The present invention has good weather resistance, hardness, anti-scouring, wear resistance and other properties. Moreover, the present invention uses inorganic components as the main components and has the advantage of low volatile organic compounds (VOCs) emissions. The present invention can be used in protective engineering of concrete and other materials in many 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, and the test results are shown in Table 3.

[0145] Adhesion test: The coatings of Examples 1 to 5 of the present invention were tested for adhesion using the test method of standard GB / T 9286-2021; with reference to GB / T 9286-2021, adhesion grade: grade 0 is the best and grade 5 is the worst;

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

[0147] Oil resistance test: The test method adopts Section 6.3.13.3 of GB / T 22374-2018 & Method C of GB / T9274-1988, 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 are visible changes after 72h. If there are no visible changes, it means that the oil resistance is good.

[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 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 principle 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 remainder of the nano inorganic filler is the main filler; Taking the total mass of the main filler as the standard, 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.

2. A protective nano hard coating according to claim 1, characterized in that: 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.

3. A protective nano hard coating according to claim 2, characterized in that: 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.

4. A protective nano hard coating according to claim 3, 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 dodecyl sulfate, and the cationic surfactant is hexadecyltrimethylammonium bromide.

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

2.

6. The protective nano hard coating according to claim 3, characterized in that: The added amounts of component A and component B are 20-25% of the mass of the corresponding processed graded nano-silicon respectively; the added amount of the second dispersed system is 8-10% of the total mass of the main filler.

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

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

1.

9. The protective nano hard coating according to claim 1, characterized in that: The coating base material is nano silica sol modified by silane coupling agent.

10. A method for preparing a protective nano hard coating according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, preparing sol, wherein the sol is a coating base material; S2. Preparation of nano solution: S2.2, preparation of 15-20nm nano-silicon: using tetraethyl orthosilicate as the main raw material, using the sol-gel process to prepare 15-20nm nano-silicon particles; S2.3, preparation of 25-50nm nano-silicon: using high-purity silane gas with a purity of ≥99.9% as the main raw material, adopting a vapor deposition method to prepare 25-50nm nano-silicon particles at 400-450°C; S2.4, preparation of 55-80nm nano-silicon: using sodium silicate as the main raw material, 55-80nm nano-silicon particles are prepared by hydrothermal method; S2.5, respectively dispersing 15-20 nm nano-silicon, 25-50 nm nano-silicon, and 55-80 nm nano-silicon in deionized water to form a suspension; then using component A and component B in the first dispersion system accordingly so that 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, uniformly mix the 15-20nm nano-silicon suspension, 25-50nm nano-silicon suspension, and 55-80nm nano-silicon suspension respectively treated by the first dispersion system to obtain a nano-silicon suspension, add a functional filler and a second dispersion system to the nano-silicon suspension, mix and stir at 300-380r / 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 stand to obtain the target coating.

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