High-transparency self-cleaning antistatic coating and preparation method thereof

Abstract

The invention discloses a high-transparency self-cleaning antistatic coating and a preparation method thereof. The method comprises the following steps: 1, adding an alcohol solvent, a cosolvent, a catalyst and nitrogen-doped carbon quantum dots into a container, uniformly mixing, adding a silane modifier, reacting, filtering, washing and drying to obtain modified nitrogen-doped carbon quantum dots; and 2, adding an alcohol solvent, a cosolvent, the modified nitrogen-doped carbon quantum dots, a silane coupling agent and an antistatic organosilicon monomer into a container, uniformly mixing, adding a catalyst, filtering, washing, and drying to obtain the nitrogen-doped carbon quantum dot grafted polysiloxane. 3, the polysiloxane containing the nitrogen-doped carbon quantum dots and a flatting agent are dissolved in an organic solvent respectively or in a mixed mode, and after the polysiloxane containing the nitrogen-doped carbon quantum dots and the flatting agent are completely dissolved, the high-transparency wear-resistant self-cleaning antistatic coating is obtained. And 4, coating a substrate with the high-transparency wear-resistant self-cleaning antistatic coating step by step or in one step. The transparent self-cleaning coating prepared by the invention has good wear-resistant and antistatic effects.

Description

Technical Field

[0001] The present invention belongs to the field of antistatic coatings. Specifically, it relates to a highly transparent self-cleaning antistatic coating, its preparation method and application, especially the use of this highly transparent wear-resistant self-cleaning coating for the protection of the surface of optical lenses. Background Art

[0002] With the wide application of optical technologies in fields such as military, aerospace, medical imaging, and consumer electronics, the performance stability of optical devices (such as lenses, sensors, laser windows, etc.) faces severe challenges. When these devices work in complex environments, their surfaces are prone to adhesion of pollutants such as dust, oil stains, and microorganisms. At the same time, the electrostatic effect will exacerbate the adsorption of particulate matter, resulting in a decrease in light transmittance, signal distortion, and even device damage. For example, the optical windows of spacecraft are prone to static charge accumulation under extreme temperature differences and radiation conditions, attracting space dust; medical endoscopes may cause cross-infection due to the retention of biological pollutants; the imaging quality of smartphone cameras and automotive lidar is affected by stains and static interference. Traditional cleaning methods such as mechanical wiping or chemical cleaning have limitations such as low efficiency, damage to the coating film, and difficulty in real-time maintenance. Therefore, the development of high-performance optical coatings with both antistatic and self-cleaning functions has become a key requirement for improving the reliability and service life of devices.

[0003] Currently, self-cleaning coating technologies mainly rely on superhydrophobic or photocatalytic principles. Superhydrophobic coatings achieve the rolling off of pollutants by constructing micro-nano rough structures (such as the lotus leaf effect), but their prominent problems include the environmental toxicity of fluorine-containing materials and insufficient mechanical durability; photocatalytic coatings (such as TiO 2 ) can degrade organic substances, but they require ultraviolet light excitation and are ineffective against non-organic pollutants. On the other hand, antistatic coatings are mostly achieved by doping conductive materials (such as ITO, graphene) or introducing an ion conductive layer, but there are often contradictions between their light transmittance and surface energy regulation and the self-cleaning function. For example, high-conductive fillers are prone to cause light scattering, and reducing the surface energy may weaken the antistatic performance. In addition, extreme environmental adaptability (such as high and low temperatures, irradiation, humidity fluctuations) and long-term stability (anti-wear, chemical corrosion resistance) are still common shortcomings of the existing technologies.

[0004] In recent years, the integration of new materials and interdisciplinary technologies has provided new ideas for the research and development of multifunctional coatings. Interface engineering of nanocomposites (such as core-shell structure design) can synergistically regulate conductivity and hydrophobicity; bionic dynamic interfaces (such as self-healing coatings based on dynamic covalent bonds) are expected to extend service life; advanced processes such as plasma treatment and atomic layer deposition (ALD) can precisely construct multifunctional gradient films. However, how to balance functional synergy, optical properties (>95% light transmittance) and large-scale preparation cost remains a bottleneck for industrial application. For example, although the antistatic layer based on carbon nanotube network has excellent conductivity, its interfacial compatibility and long-term stability with hydrophobic siloxane have not been broken through.

[0005] The present invention innovatively develops an optical-grade antistatic self-cleaning coating technology based on a dynamic covalent bond-nanocomposite interface, which is designed specifically for strengthening the surface functions of high-precision optical lenses. Through molecular-level interface engineering, a bis(vinyl)silane coupling agent is grafted onto the surface of nitrogen-doped quantum dots, enabling them to undergo three-dimensional covalent crosslinking with a hydrogen-containing polysiloxane prepolymer and a fluorosilicon-modified leveling agent through click chemistry, forming a nanoscale interpenetrating network with both high-density chemical bonding and dynamic self-adaptive characteristics. Microscopically, the aggregation and connection of particles maintain a low roughness on the coating surface. Among them, the polysiloxane and the leveling agent mainly provide the low surface energy of the coating and surface bonding with the nitrogen-doped quantum dots, and the nitrogen-doped quantum dots can reduce light reflection, thus enabling the coating to have high light transmittance. The organosilicon monomers in the coating form Si-O-Si bonds through addition reactions and are firmly bonded to the substrate, providing excellent wear resistance for the coating. Its unique microstructure and surface chemical composition endow the coating with good transparency and antistatic self-cleaning ability. The coatings prepared by the present invention have broad application prospects on the surfaces of outdoor photovoltaic modules, curtain walls, electronic screens, and laser amplifiers. Summary of the Invention

[0006] The object of the present invention is to provide a highly transparent self-cleaning antistatic coating and a preparation method thereof. This method combines surface chemical graft modification of nitrogen-doped quantum dots to improve the compatibility between the quantum dots and the matrix, and through in-situ polymerization, the nitrogen-doped quantum dots and organosilicon monomers are firmly bonded to the surface of the silicon-based material in a chemical bonding manner, realizing controllable adjustment of the wettability and roughness of the nitrogen-doped quantum dots on the substrate surface, avoiding the phenomenon of decreased transparency of the coating, and improving the wear resistance and antistatic performance of the coating.

[0007] To achieve the above-mentioned invention object, a highly transparent self-cleaning antistatic coating and a preparation method thereof, the method includes the following steps:

[0008] Step 1: Add a certain amount of alcohol solvent, co-solvent, catalyst, and nitrogen-doped quantum dots into a container at 25-40°C at one time. The concentration of the nitrogen-doped quantum dots is controlled at 1-1000 mg / mL, and the volume ratio of the alcohol solvent to the co-solvent is 0.1-10. After mixing the above reactants evenly under the condition of a rotation speed of 50-1000 rpm, add a silane modifier to the reaction system. The mass dosage of the silane modifier is 0.5%-40% of the total mass dosage of the nitrogen-doped quantum dots. After reacting for 0.5 h-30 h, filter and wash, and dry at 40°C-50°C for 10 h-30 h to obtain modified nitrogen-doped quantum dots.

[0009] Step 2: Add a certain amount of alcohol solvent, co-solvent, modified nitrogen-doped quantum dots, silane coupling agent, and antistatic organosilicon monomer into a container at one time. The mass dosage of the modified nitrogen-doped quantum dots is controlled at 0.25%-10% of the total system mass dosage, and the volume ratio of the alcohol solvent to the co-solvent is 0.1-10. After mixing the above reactants evenly under the condition of a rotation speed of 100 rpm-1000 rpm, add a catalyst to it. After reacting at 60°C for 10 h-30 h, filter and wash, and dry at 40°C-50°C for 10 h-30 h to obtain polysiloxane grafted with nitrogen-doped quantum dots.

[0010] Step 3: Dissolve the polysiloxane of nitrogen-doped quantum dots and the leveling agent separately or mixed in an organic solvent at 25°C-40°C under the condition of a rotation speed of 100-1000 rpm. The concentration of the polysiloxane is controlled at 5 wt%-30 wt%, and the mass concentration of the leveling agent is 10 wt%-20 wt%. After the polysiloxane of nitrogen-doped quantum dots and the leveling agent are completely dissolved, a highly transparent, wear-resistant, self-cleaning, and antistatic coating is obtained.

[0011] Step 4: Wipe the highly transparent, wear-resistant, self-cleaning, and antistatic coating on the substrate step by step or by one-step method. After curing for 10 min in a fume hood at 20°C-80°C, then cure at a high temperature of 100°C-200°C for 1 h-2 h. The highly transparent, wear-resistant, self-cleaning, and antistatic coating can be successfully attached to the substrate to form a highly transparent, wear-resistant, self-cleaning, and antistatic coating.

[0012] In step 1 of the present invention, the nitrogen-doped quantum dots can be obtained by existing methods: ① Synthesize nitrogen-doped quantum dots with sizes in the range of 5 nm-50 nm of TiO 2 , ZnO, Ag, Fe 3 O 4 by a hydrothermal method. ② Directly purchase commercially available nitrogen-doped TiO 2 , ZnO, Ag, Fe 3 O 4 quantum dot aqueous dispersions, where the nitrogen source is ethylenediamine.

[0013] In step 1 of the present invention, considering the modification effect, dispersion stability, transmittance and antistatic effect of the quantum dots surface, preferably, the average size of the nitrogen-doped quantum dots is controlled within 10 nm to 30 nm.

[0014] In steps 1 and 2 of the present invention, the alcohol solvent is one or more of methanol, ethanol, isopropanol, propylene glycol, butanol, 1,4-butanediol, 1,3-butanediol, and glycerol.

[0015] In steps 1 and 2 of the present invention, the co-solvent is water, dimethyl sulfoxide, and N,N-dimethylformamide.

[0016] In step 2 of the present invention, the catalyst is an ammonia-based catalyst, including but not limited to ammonia monohydrate, hydrazine hydrate, etc. When using the ammonia-based catalyst, it should be added drop by drop. When adding the catalyst drop by drop, the pH value should be monitored continuously using a pH meter. When the pH value reaches 10 to 11, the addition of the catalyst can be stopped.

[0017] In step 2 of the present invention, the method of mixing evenly is magnetic stirring, and the time is 1 to 2 h.

[0018] In step 2 of the present invention, the method of filtration and washing: The reaction system is placed in a high-speed centrifuge for centrifugation, the centrifugation speed is 5000 to 8000 rpm, and the centrifugation time is 5 to 10 min; after centrifugation, the mixture is filtered and separated from the supernatant. After separation, the mixture is ultrasonically dispersed with water and then placed in a high-speed centrifuge for centrifugation again, the centrifugation speed is 5000 to 8000 rpm, and the centrifugation time is 5 to 10 min; repeat this three times to obtain a completely washed product.

[0019] In step 1 of the present invention, the silane modifier is several of γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, cetyltrimethoxysilane, and cetyltriethoxysilane.

[0020] In step 2 of the present invention, the silane coupling agent is several of phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, phenyltriisopropoxysilane, phenyltri-n-butoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, ethylphenyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, and methylethyldimethoxysilane.

[0021] In step 2 of the present invention, the antistatic organosilicon monomer is selected from at least one of the following: methyltriethoxysilane quaternary ammonium salt, methyldimethoxysilane quaternary ammonium salt, N,N-dimethyldodecylaminopropyltrimethoxysilane ammonium chloride, N-allyldimethylamine and 3-chloropropyltrimethoxysilane, acrylate ethoxysilane. Considering the actual antistatic effect, N,N-dimethyldodecylaminopropyltrimethoxysilane ammonium chloride and N-allyldimethylamine and 3-chloropropyltrimethoxysilane are preferred; the dosage is 0.2 wt% to 10 wt% of the mass of the silane coupling agent.

[0022] In step 2 of the present invention, the polysiloxane refers to a polymer in which the main chain is composed of repeating units of silicon-oxygen (Si-O) bonds, and organic groups are connected to the silicon atoms.

[0023] In step 3 of the present invention, the leveling agent is amino-modified polydimethylsiloxane, carboxyl-modified polydimethylsiloxane, epoxy-modified polydimethylsiloxane, isocyanate-modified polydimethylsiloxane, mercapto-modified polydimethylsiloxane.

[0024] In step 3 of the present invention, "dissolving separately or mixing in an organic solvent" refers to two ways of preparing the light-transmitting highly transparent wear-resistant self-cleaning coating. Method 1: Take a certain amount of polysiloxane with nitrogen-doped quantum dots and a leveling agent at 25 - 40 °C, and dissolve them separately in the same volume of organic solvent; Method 2: Take a certain amount of polysiloxane with nitrogen-doped quantum dots and a leveling agent at 25 - 40 °C, and dissolve them in a certain mass of organic solvent.

[0025] In step 3 of the present invention, the organic solvent is one or more of methanol, ethanol, ethyl acetate, acetone, n-hexadecane, cyclohexane, tetrahydrofuran, dichloromethane, carbon tetrachloride, toluene, xylene.

[0026] In step 4 of the present invention, "coating by steps or in one step" refers to two ways of coating the light-transmitting highly transparent wear-resistant self-cleaning coating. Method 1: Take a certain amount of organic solvent in which polysiloxane with nitrogen-doped quantum dots is dissolved, and wipe it on the substrate, and then take a certain amount of organic solvent in which the leveling agent is dissolved, and wipe it on the substrate; Method 2: Take a certain amount of organic solvent in which polysiloxane with nitrogen-doped quantum dots and a leveling agent are dissolved, and wipe it on the substrate.

[0027] In step 4 of the present invention, the way of wiping is to dip a non-woven fabric into about 1 - 1000 μL of the light-transmitting highly transparent wear-resistant self-cleaning coating and evenly apply the light-transmitting highly transparent wear-resistant self-cleaning coating thinly on the substrate at a speed of 1 - 5 m / s.

[0028] In step 4 of the present invention, the substrate is a silicon-based material such as glass, silicon wafer, etc., and the attached debris on it needs to be washed off with water in advance and dried at 40 - 80 °C before it can be used as a substrate.

[0029] In the present invention, nitrogen-doped quantum dots with appropriate sizes have excellent antireflection functions. However, since there are only hydrophilic hydroxyl groups on their surfaces and the groups are too single, the surface properties of the nitrogen-doped quantum dots are very single, which greatly limits the applications of the nitrogen-doped quantum dots. By surface-modifying the nitrogen-doped quantum dots, reactive amphiphilic groups are grafted onto the surfaces of the nitrogen-doped quantum dots through chemical reactions, greatly broadening the application scope of the nitrogen-doped quantum dots. In particular, the present invention adopts an in-situ polymerization method, enabling the nitrogen-doped quantum dots to have an extremely stable chemical bond with polysiloxane and a leveling agent. There is quite good compatibility between the silicone and the nitrogen-doped quantum dots, avoiding the agglomeration of the nitrogen-doped quantum dots in the coating, achieving a high degree of dispersion of the nitrogen-doped quantum dots in the coating, and the nitrogen-doped quantum dots with a certain mechanical strength provide a certain degree of abrasion resistance for the coating.

[0030] The inventors have found through in-depth research that since a strong cross-linked network is formed between the silicone and the nitrogen-doped quantum dots, the coating is structurally given ultra-high hardness; while the nitrogen-doped quantum dots are evenly and firmly connected to the polysiloxane and the leveling agent, the surface properties of the coating are uniform and smooth, and the nitrogen-doped quantum dots are highly dispersed in the coating, fundamentally eliminating the occurrence of diffuse reflection and enhancing the light transmittance of the coating. Therefore, the coating has excellent transparency.

[0031] Compared with the prior art, the technical solution of the present invention has the following technical advantages:

[0032] 1) The process is simple, the raw materials are easily available, and the cost is low; 2) The coating is highly transparent. The light transmittance of the coated glass reaches up to 91.5% at most in the visible light range, and the average light transmittance is 90.2%. The light transmittance is better than that of the glass substrate and has good commercial uses. (It is known that the highest light transmittance of the glass in the visible light range is 91.4%, and the average light transmittance is 90.1%); 3) The coating is super wear-resistant and can maintain the self-cleaning performance after being scratched 1400 times with scissors; 4) The coating has ultra-high adhesion to the substrate, has a certain tolerance to acids, alkalis, and salts, and has a long service life. 5) The present invention connects the nitrogen-doped quantum dots, polysiloxane, and leveling agent together through chemical bonds, taking into account the properties of high transparency, super wear resistance, and self-cleaning at the same time, and also has antistatic properties. Description of the Drawings

[0033] Figure 1 It is a comparison diagram of the SEM images of the coating before and after scratching of the present invention. Detailed Embodiments

[0034] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following will further elaborate on the present invention in combination with the accompanying drawings and examples. The specific examples described herein are only used to explain the present invention and are not used to limit the present invention. The protection scope of the present invention is by no means limited to this.

[0035] Through in-situ polycondensation, the nitrogen-doped quantum dots form extremely stable covalent bonds with polysiloxane and leveling agent through chemical bonds. Due to the good compatibility between silicone and silica particles, the agglomeration of nitrogen-doped quantum dots in the coating is avoided, achieving a high degree of dispersion of nitrogen-doped quantum dots in the coating, greatly reducing the occurrence of diffuse reflection, enhancing the light transmittance of the coating, and thus the coating has excellent transparency. In the present invention, due to the formation of a strong crosslinked network between silicone monomers and nitrogen-doped quantum dots, the coating is structurally given ultra-high hardness, and the nitrogen-doped quantum dots with a certain mechanical strength provide excellent wear resistance for the coating. In addition, the prepared transparent wear-resistant coating has good self-cleaning and antistatic effects.

[0036] Example 1:

[0037] At 25 °C, 1 g of nitrogen-doped titanium dioxide quantum dots (10 nm) was dissolved in 30 mL of an aqueous ethanol solution (the volume ratio of ethanol to water was 3:1). The pH value of the reaction system was adjusted to 10 - 11 using ammonia monohydrate. After stirring for 1 h under the condition that the magnetic stirrer speed was 600 rpm, 0.1 g of γ-glycidoxypropyltrimethoxysilane and 0.05 g of cetyltrimethylsilane were added to the reaction system, and stirring was carried out for 8 h at 600 rpm. The product was centrifuged, separated and washed; after drying at 45 °C for 10 h, modified nitrogen-doped titanium dioxide quantum dots were obtained.

[0038] 0.0655 g of modified nitrogen-doped titanium dioxide quantum dots was dissolved in 30 mL of an aqueous ethanol solution (the volume ratio of ethanol to water was 3:1). 3.966 g of phenyltrimethoxysilane, 2.404 g of dimethyldimethoxysilane, 2.363 g of γ-glycidoxypropyltrimethoxysilane, and 0.437 g of N,N-dimethyldodecylaminopropyltrimethoxysilane ammonium chloride were added thereto, and stirring was carried out for 1 h at 600 rpm. The pH value of the reaction system was adjusted to 10.5 using ammonia monohydrate. After reacting at 60 °C for 10 h, the product was centrifuged and washed, and dried at 45 °C for 10 h to obtain polysiloxane of nitrogen-doped modified titanium dioxide quantum dots.

[0039] At 25 °C, 0.5 g of polysiloxane with nitrogen-doped modified titanium dioxide quantum dots and 1.5 g of amino-modified polydimethylsiloxane were respectively dissolved in 5 g of xylene. After mixing at 800 rpm for 1 h, a non-woven fabric was used to dip 50 μL of the xylene solution of polysiloxane with nitrogen-doped modified titanium dioxide quantum dots and evenly coat it on a glass slide at a speed of 3 m / s. Then, a non-woven fabric was used to dip 50 μL of the xylene solution of amino-modified polydimethylsiloxane and evenly coat it on the glass slide at the same speed. After curing at 25 °C for 10 min, the temperature was raised to 120 °C and cured for 1 h to obtain a highly transparent, super wear-resistant, self-cleaning and antistatic coating. The water contact angle of the coating was measured by dynamic video contact angle, the light transmittance of the coating was measured by ultraviolet-visible spectrophotometer in the wavelength range of 300 - 800 nm, and the wear resistance of the coating was measured according to ASTM D 4213-2008. Bulk samples were prepared by the pressing method, and the surface resistivity (Ω / sq) of the coating was measured by the four-probe method (ASTM D4496). The water contact angle of the prepared coating was 126°, and the light transmittance after coating on the glass was 90.8%. According to GB / T21866-2008, the bactericidal rates of the coating against Escherichia coli and Staphylococcus aureus were 97% and 95% respectively. The surface resistivity of the coating was 7.3×10 7 Ω / sq, showing excellent antistatic property.

[0040] Comparative Example 1:

[0041] At 25 °C, 1 g of nitrogen-doped titanium dioxide quantum dots (30 nm) was dissolved in an aqueous solution of 30 mL of ethanol (the volume ratio of ethanol to water was 3:1). The pH value of the reaction system was adjusted to 10 - 11 using aqueous ammonia. After stirring for 1 h under the condition that the magnetic stirrer speed was 600 rpm, 0.1 g of γ-glycidoxypropyltrimethoxysilane and 0.05 g of cetyltrimethylsilane were added to the reaction system, and stirred at 600 rpm for 8 h. The product was centrifuged, separated and washed; after drying at 45 °C for 10 h, modified nitrogen-doped titanium dioxide quantum dots were obtained.

[0042] 0.0655 g of modified nitrogen-doped titanium dioxide quantum dots was dissolved in an aqueous solution of 30 mL of ethanol (the volume ratio of ethanol to water was 3:1). 3.966 g of phenyltrimethoxysilane, 2.404 g of dimethyldimethoxysilane, 2.363 g of γ-glycidoxypropyltrimethoxysilane, and 0.437 g of N,N-dimethyldodecylaminopropyltrimethoxysilane ammonium chloride were added thereto, and stirred at 600 rpm for 1 h. The pH value of the reaction system was adjusted to 10.5 using aqueous ammonia. After reacting at 60 °C for 10 h, the product was centrifuged and washed, and dried at 45 °C for 10 h to obtain polysiloxane with nitrogen-doped modified titanium dioxide quantum dots.

[0043] At 25 °C, 0.5 g of polysiloxane with nitrogen-doped modified titanium dioxide quantum dots and 1.5 g of amino-modified polydimethylsiloxane were respectively dissolved in 5 g of xylene. After mixing at 800 rpm for 1 h, 50 μL of the xylene solution containing polysiloxane with nitrogen-doped modified titanium dioxide quantum dots was dipped with non-woven fabric and uniformly coated on a glass slide at a speed of 3 m / s. Then, 50 μL of the xylene solution containing amino-modified polydimethylsiloxane was dipped with non-woven fabric and uniformly coated on the glass slide at the same speed. After curing at 25 °C for 10 min, the temperature was raised to 120 °C and cured for 1 h to obtain a highly transparent, super wear-resistant, self-cleaning and antistatic coating. The water contact angle of the coating was measured by dynamic video contact angle, the light transmittance of the coating was measured by ultraviolet-visible spectrophotometer in the wavelength range of 300 - 800 nm, and the wear resistance of the coating was measured according to ASTM D 4213-2008. Bulk samples were prepared by the tablet pressing method, and the surface resistivity (Ω / sq) of the coating was measured by the four-probe method (ASTM D4496). The water contact angle of the prepared coating was 120°, and the light transmittance after coating on the glass was 93.5%. The bactericidal rates of the coating against Escherichia coli and Staphylococcus aureus were 95% and 92% respectively measured according to GB / T21866-2008. The surface resistivity of the coating was 1.5×10 6 Ω / sq, showing certain antistatic property.

[0044] Comparative Example 2:

[0045] At 25 °C, 1 g of nitrogen-doped titanium dioxide quantum dots (30 nm) was dissolved in an aqueous solution of 30 mL of ethanol (the volume ratio of ethanol to water was 3:1). The pH value of the reaction system was adjusted to 10 - 11 with ammonia monohydrate. After stirring for 1 h under the condition that the magnetic stirrer speed was 600 rpm, 0.1 g of γ-glycidoxypropyltrimethoxysilane and 0.05 g of cetyltrimethylsilane were added to the reaction system, and stirred at 600 rpm for 8 h. The product was centrifuged, separated and washed; after drying at 45 °C for 10 h, modified nitrogen-doped titanium dioxide quantum dots were obtained.

[0046] Take 0.0655 g of modified nitrogen-doped titanium dioxide quantum dots and dissolve them in an aqueous solution of 30 mL of ethanol (the volume ratio of ethanol to water was 3:1). Add 3.966 g of phenyltrimethoxysilane, 2.404 g of dimethyldimethoxysilane, 2.363 g of γ-glycidoxypropyltrimethoxysilane, and 0.437 g of N,N-dimethyldodecylaminopropyltrimethoxysilane ammonium chloride to it, and stir at 600 rpm for 1 h. The pH value of the reaction system was adjusted to 10.5 with ammonia monohydrate. After reacting at 60 °C for 10 h, the product was centrifuged and washed, and dried at 45 °C for 10 h to obtain polysiloxane with nitrogen-doped modified titanium dioxide quantum dots.

[0047] At 25 °C, 0.5 g of polysiloxane doped with nitrogen-modified titanium dioxide quantum dots and 1.5 g of amino-modified polydimethylsiloxane were respectively dissolved in 5 g of xylene. After mixing at 800 rpm for 1 h, 50 μL of the xylene solution containing polysiloxane doped with nitrogen-modified titanium dioxide quantum dots was dipped with a non-woven fabric and uniformly coated on a glass slide at a speed of 3 m / s. Then, 50 μL of the xylene solution containing amino-modified polydimethylsiloxane was dipped with a non-woven fabric and uniformly coated on the glass slide at the same speed. After curing at 25 °C for 10 min, the temperature was raised to 120 °C and cured for 1 h to obtain a highly transparent, super wear-resistant, self-cleaning and antistatic coating. The water contact angle of the coating was measured by dynamic video contact angle, the light transmittance of the coating was measured by ultraviolet-visible spectrophotometer in the wavelength range of 300 - 800 nm, and the wear resistance of the coating was measured according to ASTM D 4213-2008. Bulk samples were prepared by the pressing method, and the surface resistivity (Ω / sq) of the coating was measured by the four-probe method (ASTM D4496). The water contact angle of the prepared coating was 120°, and the light transmittance after coating on glass was 93.5%. According to GB / T21866-2008, the bactericidal rates of the coating against Escherichia coli and Staphylococcus aureus were 95% and 92% respectively. The surface resistivity of the coating was 1.5×10 6 Ω / sq, showing certain antistatic properties.

[0048] Example 2:

[0049] At 30 °C, 2 g of nitrogen-doped graphene quantum dots (30 nm) were dissolved in a dimethyl sulfoxide solution of 60 mL of isopropanol (the volume ratio of isopropanol to dimethyl sulfoxide was 3:1). The pH value of the reaction system was adjusted to 10 - 11 using aqueous ammonia. After stirring for 1 h under the condition that the magnetic stirrer speed was 800 rpm, 0.1 g of γ-glycidoxypropyltriethoxysilane and 0.05 g of cetyltriethylsilane were added to the reaction system, and stirred at 800 rpm for 12 h. The product was centrifuged, separated and washed; after drying at 50 °C for 10 h, modified nitrogen-doped graphene quantum dots were obtained.

[0050] Take 0.1310 g of modified nitrogen-doped graphene quantum dots and dissolve them in a dimethyl sulfoxide solution of 60 mL of isopropanol (the volume ratio of isopropanol to dimethyl sulfoxide was 3:1). Add 3.966 g of phenyltriethoxysilane, 2.404 g of dimethyldiethoxysilane, 2.363 g of γ-glycidoxypropylmethyldiethoxysilane, and 0.873 g of N-allyldimethylamine to it, and stir at 800 rpm for 1 h. The pH value of the reaction system was adjusted to 10.5 using aqueous ammonia. After reacting at 60 °C for 15 h, the product was centrifuged and washed, and dried at 50 °C for 10 h to obtain polysiloxane of nitrogen-doped modified graphene quantum dots.

[0051] At 30 °C, 1.0 g of polysiloxane doped with nitrogen-doped modified graphene quantum dots and 2.0 g of epoxy-modified polydimethylsiloxane were mixed and dissolved in 10 g of tetrahydrofuran. After mixing for 1 h at 1000 rpm, 100 μL of the tetrahydrofuran solution containing polysiloxane doped with nitrogen-doped modified graphene quantum dots and epoxy-modified polydimethylsiloxane was dipped with a non-woven fabric and uniformly coated on a glass slide at a speed of 3 m / s. After curing at 45 °C for 10 min, the temperature was then raised to 150 °C and cured for 1.5 h to obtain a highly transparent, super wear-resistant, self-cleaning and antistatic coating. The water contact angle of the coating was measured by dynamic video contact angle, the light transmittance of the coating was measured using a UV-visible spectrophotometer in the wavelength range of 300 - 800 nm, and the wear resistance of the coating was measured according to ASTM D 4213-2008. The water contact angle of the prepared coating was 140°, and the light transmittance after coating on the glass was 83.4%. According to GB / T21866-2008, the bactericidal rates of the coating against Escherichia coli and Staphylococcus aureus were 97% and 95% respectively. The surface resistivity of the coating was 1.5×10 8 Ω / sq, with excellent antistatic properties.

[0052] Example 3:

[0053] At 30 °C, 0.5 g of nitrogen-doped silver quantum dots (8 nm) was dissolved in a dimethyl sulfoxide solution of 30 mL of methanol (the volume ratio of methanol to dimethyl sulfoxide was 3:1). The pH value of the reaction system was adjusted to 10 - 11 using hydrazine hydrate. After stirring for 1 h under the condition that the magnetic stirrer speed was 400 rpm, 0.05 g of γ-glycidoxypropyltriethoxysilane and 0.025 g of cetyltriethylsilane were added to the reaction system, and stirred for 6 h under the condition of 400 rpm. The product was centrifuged, separated and washed; after drying at 45 °C for 12 h, modified nitrogen-doped silver quantum dots were obtained.

[0054] Take 0.0655 g of modified nitrogen-doped silver quantum dots and dissolve them in a dimethyl sulfoxide solution of 30 mL of methanol (the volume ratio of methanol to dimethyl sulfoxide was 3:1). Add 3.966 g of phenyltriethoxysilane, 2.404 g of dimethyldiethoxysilane, 2.363 g of γ-glycidoxypropyltrimethoxysilane, and 0.218 g of 3-chloropropyltrioxysilane to it, and stir for 1 h under the condition of 600 rpm. Use hydrazine hydrate to adjust the pH value of the reaction system to 10.5. After reacting at 60 °C for 10 h, the product was centrifuged and washed, and dried at 45 °C for 12 h to obtain polysiloxane doped with nitrogen-doped modified silver quantum dots.

[0055] At 25 °C, 0.5 g of polysiloxane doped with nitrogen-modified silver quantum dots and 1.5 g of isocyanate-modified polydimethylsiloxane were mixed and dissolved in 10 g of dichloromethane. After mixing for 1 h at 800 rpm, 100 μL of dichloromethane solution containing polysiloxane doped with nitrogen-modified silver quantum dots and isocyanate-modified polydimethylsiloxane was dipped with non-woven fabric and uniformly coated on a glass slide at a speed of 3 m / s. After curing for 10 min at 25 °C, the temperature was then raised to 120 °C and cured for 1.5 h to obtain a highly transparent, super wear-resistant, self-cleaning and antistatic coating. The water contact angle of the coating was measured by dynamic video contact angle, the light transmittance of the coating was measured using a UV-visible spectrophotometer in the wavelength range of 300 - 800 nm, and the wear resistance of the coating was measured according to ASTM D 4213-2008. The water contact angle of the prepared coating was 118°, and the light transmittance after coating on glass was 90.1%. According to GB / T21866-2008, the bactericidal rates of the coating against Escherichia coli and Staphylococcus aureus were 93% and 91% respectively. The surface resistivity of the coating was 6.7×10 7 Ω / sq, having excellent antistatic property.

[0056] Example 4:

[0057] At 25 °C, 1 g of nitrogen-doped zinc oxide quantum dots (10 nm) was dissolved in 30 mL of an aqueous solution of methanol (volume ratio of methanol to water was 3:1). The pH value of the reaction system was adjusted to 10 - 11 using hydrazine hydrate. After stirring for 1 h under the condition that the magnetic stirrer speed was 800 rpm, 0.1 g of γ-glycidoxypropyltrimethoxysilane and 0.05 g of cetyltrimethylsilane were added to the reaction system, and stirred for 15 h at 800 rpm. The product was centrifuged, separated and washed; after drying at 50 °C for 14 h, modified nitrogen-doped zinc oxide quantum dots were obtained.

[0058] Take 0.0655 g of modified nitrogen-doped zinc oxide quantum dots and dissolve them in 30 mL of an aqueous solution of methanol (volume ratio of methanol to water was 3:1). Add 3.966 g of phenyltrimethoxysilane, 2.404 g of dimethyldimethoxysilane, 2.363 g of γ-glycidoxypropyltrimethoxysilane, and 0.437 g of N,N-dimethyldodecylaminopropyltrimethoxysilane ammonium chloride thereto, and stir at 800 rpm for 1 h. Use hydrazine hydrate to adjust the pH value of the reaction system to 10.5. After reacting at 60 °C for 15 h, the product was centrifuged and washed, and dried at 50 °C for 14 h to obtain polysiloxane of nitrogen-doped zinc oxide quantum dots.

[0059] At 30 °C, 0.5 g of polysiloxane with nitrogen-doped modified zinc oxide quantum dots and 1.5 g of amino-modified polydimethylsiloxane were respectively dissolved in 5 g of tetrahydrofuran. After mixing at 800 rpm for 1 h, a non-woven fabric was used to dip 50 μL of the tetrahydrofuran solution of polysiloxane with nitrogen-doped modified zinc oxide quantum dots and uniformly coat it on a glass slide at a speed of 3 m / s. Then, a non-woven fabric was used to dip 50 μL of the tetrahydrofuran solution of amino-modified polydimethylsiloxane and uniformly coat it on the glass slide at the same speed. After curing at 45 °C for 10 min, the temperature was raised to 150 °C and cured for 1.5 h to obtain a highly transparent, super wear-resistant, self-cleaning and antistatic coating. The water contact angle of the coating was measured by dynamic video contact angle, the light transmittance of the coating was measured using a UV-visible spectrophotometer in the wavelength range of 300 - 800 nm, and the wear resistance of the coating was measured according to ASTM D 4213-2008. The water contact angle of the prepared coating was 123°, and the light transmittance after coating on the glass was 89.2%. According to GB / T21866-2008, the bactericidal rates of the coating against Escherichia coli and Staphylococcus aureus were 92% and 90% respectively. The surface resistivity of the coating was 5.2×10 7 Ω / sq, showing excellent antistatic property.

[0060] Example 5:

[0061] At 30 °C, 1 g of nitrogen-doped titanium dioxide quantum dots (5 nm) was dissolved in 30 mL of an aqueous solution of butanediol (the volume ratio of butanediol to water was 3:1). The pH value of the reaction system was adjusted to 10 - 11 using aqueous ammonia. After stirring for 1 h under the condition that the magnetic stirrer speed was 800 rpm, 0.1 g of γ-glycidoxypropyltrimethoxysilane and 0.05 g of cetyltrimethylsilane were added to the reaction system, and stirred at 800 rpm for 12 h. The product was centrifuged, separated and washed; after drying at 50 °C for 14 h, modified nitrogen-doped titanium dioxide quantum dots were obtained.

[0062] 0.0655 g of modified nitrogen-doped titanium dioxide quantum dots was dissolved in 30 mL of an aqueous solution of butanediol (the volume ratio of butanediol to water was 3:1). 3.966 g of phenyltrimethoxysilane, 2.404 g of dimethyldimethoxysilane, 2.363 g of γ-glycidoxypropyltrimethoxysilane, and 0.437 g of N,N-dimethyldodecylaminopropyltrimethoxysilane ammonium chloride were added thereto, and stirred at 800 rpm for 1 h. The pH value of the reaction system was adjusted to 10.5 using aqueous ammonia. After reacting at 60 °C for 15 h, the product was centrifuged and washed, and dried at 50 °C for 14 h to obtain polysiloxane with nitrogen-doped modified titanium dioxide quantum dots.

[0063] At 30 °C, 0.5 g of polysiloxane doped with nitrogen-doped modified titanium dioxide quantum dots and 1.5 g of amino-modified polydimethylsiloxane were respectively dissolved in 5 g of tetrahydrofuran. After mixing at 800 rpm for 1 h, 50 μL of the tetrahydrofuran solution of polysiloxane doped with nitrogen-doped modified titanium dioxide quantum dots was dipped with a non-woven fabric and evenly coated on a glass slide at a speed of 3 m / s. Then, 50 μL of the xylene solution of amino-modified polydimethylsiloxane was dipped with a non-woven fabric and evenly coated on the glass slide at the same speed. After curing at 45 °C for 10 min, the temperature was raised to 150 °C and cured for 1.5 h to obtain a highly transparent, super wear-resistant, self-cleaning and antistatic coating. The water contact angle of the coating was measured by dynamic video contact angle, the light transmittance of the coating was measured by ultraviolet-visible spectrophotometer in the wavelength range of 300 - 800 nm, and the wear resistance of the coating was measured according to ASTM D 4213-2008. The water contact angle of the prepared coating was 115°, and the light transmittance after coating on the glass was 88.6%. According to GB / T21866-2008, the bactericidal rates of the coating against Escherichia coli and Staphylococcus aureus were 96% and 94% respectively. The surface resistivity of the coating was 4.3×10 7 Ω / sq, with excellent antistatic properties.

[0064] Table 1

[0065]

[0066] As shown in Table 1, Examples and Comparative Examples, the particle size, dosage and type of nitrogen-doped quantum dots are directly related to the contact angle and light transmittance of the coating. In Comparative Example 1, the particle size of the nitrogen-doped quantum dots was only 10 nm, which greatly improved the light transmittance, so the light transmittance increased to 93.5%. However, the too small particle size reduced the surface roughness of the coating, affecting the self-cleaning performance of the coating and reducing the contact angle of the coating to only 120°; while in Comparative Example 2, the particle size of the nitrogen-doped quantum dots was 30 nm. Although the contact angle of the coating increased to 128°, the light transmittance decreased to 87.3%; in Example 2, the dosage of nitrogen-doped graphene quantum dots was doubled, and the surface resistivity of the coating was 1.5×10 8 Ω / sq, with excellent antistatic properties, but the light transmittance decreased significantly to 83.4%, which was not worth the loss; in order to comprehensively consider the self-cleaning and high transparency performance, it can be seen that the particle size and dosage in Example 1 are the best; therefore, the particle size and dosage in Example 1 were used in Examples 4 and 5, and the type of nitrogen-doped quantum dots was changed. However, obviously, the contact angle and light transmittance were lower than those in Example 1. It can be seen that the nitrogen-doped titanium dioxide quantum dots in Example 1 have the best self-cleaning and antistatic effects while maintaining the high wear resistance and antibacterial properties of the coating.

[0067] As Figure 1As shown, a friction cycle test was carried out on the coating in Example 1: A sharp pair of scissors was held at a 45° angle to the coating and slid back and forth forcefully and quickly. The appearance of the coating was photographed every 100 times and the water contact angle was measured. Figure 1 Comparison of SEM images of the coating before and after 1000 scratches (the left image is the original coating and the right image is the coating after 1000 scratches).

Claims

1. A method for preparing a highly transparent self-cleaning antistatic coating, characterized in that: The following steps are involved: Step 1, adding a certain amount of alcohol solvent, co-solvent, catalyst, and nitrogen-doped quantum dots into a container at 25°C to 40°C at one time, wherein the concentration of the nitrogen-doped quantum dots is controlled at 1 to 1000 mg / mL, and the volume ratio of the alcohol solvent to the co-solvent is 0.1 to 10; after the above reactants are mixed evenly at a speed of 50 to 1000 rpm, a silane modifier is added to the reaction system, and after reacting for 0.5h to 30h, the reaction is filtered and washed, and dried at 40°C to 50°C for 10h to 30h to obtain modified nitrogen-doped quantum dots; Step 2: adding a certain amount of alcohol solvent, co-solvent, modified nitrogen-doped quantum dots, silane coupling agent, and antistatic silicone monomer into a container at one time, mixing the above reactants evenly at a rotation speed of 100 rpm to 1000 rpm, adding a catalyst thereto, reacting at 60° C. for 10 h to 30 h, filtering and washing, and drying at 40° C. to 50° C. for 10 h to 30 h to obtain polysiloxane grafted with nitrogen-doped quantum dots; Step 3, dissolving nitrogen-doped quantum dot polysiloxane and a leveling agent in an organic solvent at 25°C to 40°C and a rotation speed of 100 to 1000 rpm, wherein the mass concentration of the nitrogen-doped quantum dot polysiloxane is controlled to be 5wt% to 30wt% of the total system, and the total system includes nitrogen-doped quantum dot polysiloxane, a leveling agent and an organic solvent; the mass concentration of the leveling agent is 10wt% to 20wt%, and after the nitrogen-doped quantum dot polysiloxane and the leveling agent are completely dissolved, a highly transparent, wear-resistant, self-cleaning, antistatic coating is obtained; Step 4: Apply the highly transparent, wear-resistant, self-cleaning, antistatic coating to the substrate step by step or in one step, cure it in a fume hood at 20°C to 80°C for 10 minutes, and then cure it at a high temperature of 100°C to 200°C for 1h to 2h. The highly transparent, wear-resistant, self-cleaning, antistatic coating is successfully attached to the substrate to form a highly transparent, wear-resistant, self-cleaning, antistatic coating.

2. The method for preparing a highly transparent self-cleaning antistatic coating according to claim 1, characterized in that: The mass amount of the silane modifier in step 1 is 0.5% to 40% of the total mass amount of the nitrogen-doped quantum dots.

3. The method for preparing a highly transparent self-cleaning antistatic coating according to claim 1, characterized in that: In step 1, the average size of the nitrogen-doped quantum dots is controlled to be between 10 nm and 30 nm.

4. The method for preparing a highly transparent self-cleaning antistatic coating according to claim 2 or 3, characterized in that: The nitrogen-doped quantum dots in step 1 are obtained by the following method: ① Synthesize nitrogen-doped quantum dots of TiO2, ZnO, Ag, and Fe3O4 with a size range of 5nm to 50nm by hydrothermal method; ② Directly purchase commercially available nitrogen-doped TiO2, ZnO, Ag, Fe3O4 quantum dot aqueous dispersions with a size range of 5nm to 50nm, wherein the nitrogen source is ethylenediamine.

5. The method for preparing a highly transparent self-cleaning antistatic coating according to claim 2 or 3, characterized in that: In step 2, the mass amount of the modified nitrogen-doped quantum dots is controlled to be 0.25% to 10% of the total system mass amount, and the volume ratio of the alcohol solvent to the co-solvent is 0.1 to 10.

6. A highly transparent self-cleaning antistatic coating and a preparation method thereof according to claim 1, characterized in that: The nitrogen-doped quantum dot polysiloxane in step 2 refers to a polymer whose main chain is composed of repeating silicon-oxygen bonds, wherein an organic group is connected to the silicon atom.

7. A highly transparent self-cleaning antistatic coating and a preparation method thereof according to claim 6, characterized in that: In step 3, the nitrogen-doped quantum dot polysiloxane and the leveling agent are dissolved in an organic solvent, which specifically means that the nitrogen-doped quantum dot polysiloxane and the leveling agent are dissolved in the same volume of organic solvent respectively.

8. A highly transparent self-cleaning antistatic coating and a preparation method thereof according to claim 6, characterized in that: The nitrogen-doped quantum dot polysiloxane and the leveling agent are dissolved in an organic solvent, which specifically means that the nitrogen-doped quantum dot polysiloxane and the leveling agent are mixed and dissolved in a certain mass of an organic solvent.

9. A highly transparent self-cleaning antistatic coating and a preparation method thereof according to claim 1, 6 or 7, characterized in that: The step-by-step application described in step 4 is as follows: A certain amount of organic solvent containing nitrogen-doped quantum dots in polysiloxane is taken and rubbed on the substrate, and then a certain amount of organic solvent containing a leveling agent is taken and rubbed on the substrate.

10. A highly transparent self-cleaning antistatic coating and a preparation method thereof according to claim 1, 6 or 8, characterized in that: The one-step wiping described in step 4 is specifically as follows: A certain amount of organic solvent containing nitrogen-doped quantum dot polysiloxane and a leveling agent is taken and applied on a substrate.

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