High-transparency super-hydrophilic coating and preparation method thereof

Abstract

The invention belongs to the technical field of super-hydrophilic new materials, and particularly relates to a high-transparency super-hydrophilic coating and a preparation method thereof. The super-hydrophilic self-cleaning coating is prepared from the following components: titanium dioxide nanoparticles, an organic hydrophilic polymer acrylate monomer, an anionic surfactant sodium alpha-olefin sulfonate and a solvent. According to the invention, titanium dioxide is introduced, so that the coating has certain photocatalytic activity and hydrophilicity; the acrylate monomer and the sodium alpha-olefin sulfonate are beneficial for further improving the hydrophilicity, the surface energy and the film-forming property of the coating. The light transmittance of the prepared coated glass reaches 91.8%, and the coated glass is suitable for equipment with relatively high requirements on the light transmittance; the static water contact angle is only 2.8 degrees, and a stable super-hydrophilic state can be achieved; organic pollutants adsorbed on the surface of the coating can be catalytically decomposed under ultraviolet light, and an excellent self-cleaning effect is achieved. According to the method, the super-hydrophilic self-cleaning coating with ultrahigh transparency and excellent photocatalytic activity can be simply, conveniently and efficiently prepared at room temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of super-hydrophilic new materials, and in particular relates to a highly transparent super-hydrophilic coating and a preparation method thereof. Background Art

[0002] When photovoltaic panels, glass, marine vessels and other equipment are used for a long time, they need to be cleaned regularly to maintain their ideal optimal performance. When photovoltaic panels are used outdoors, dust accumulation will seriously attenuate the power of the equipment; dust accumulation on the glass surface will reduce visibility; when ships are sailing in the ocean, the attachment of marine organisms will cause great harm to the ships; regular cleaning and maintenance will result in expensive manpower and material costs. When a layer of super-hydrophilic self-cleaning coating is applied to the surface of these devices, the manpower and material costs of cleaning can be significantly reduced.

[0003] The self-cleaning mechanism of super-hydrophilic self-cleaning coatings refers to the water contact angle on the coating surface being less than 5°. A small amount of water droplets can form a water film on the glass surface, which prevents the contact between pollutants and the material surface, washes away the surface pollution, and achieves self-cleaning of the surface. For super-hydrophilic self-cleaning coatings used in the photovoltaic field, ensuring that the material surface has high transparency and super-hydrophilic properties is the key to coating preparation.

[0004] Superhydrophilic self-cleaning coatings are related to the surface water contact angle. When the water contact angle is less than 90°, the solid surface is called a hydrophilic surface; and when the contact angle is close to 0°, it is called a superhydrophilic surface. The theoretical basis of superhydrophilic surface wettability is mainly composed of two aspects: surface energy and roughness-induced superhydrophilicity and photo-induced superhydrophilicity: the surface of the material has high surface energy and high roughness; or the surface can form a superhydrophilic state under the action of light. In recent years, titanium dioxide has been widely used as an excellent self-cleaning material. Titanium dioxide has excellent photoelectric properties, photostability, low cost, non-toxicity and environmental friendliness. It is a wide candidate material for superhydrophilic self-cleaning surfaces and coatings. Preparing titanium dioxide solution, doping and modifying titanium dioxide, and compounding with other inorganic materials are all excellent preparation methods for superhydrophilic coatings.

[0005] Regarding the report on the preparation of titanium dioxide solution, Muhammad et al. developed a self-cleaning transparent coating on a glass substrate by dip coating a TiO2-KH550-PEG mixed solution with super hydrophilicity and good anti-fog properties in 2022; this paper requires high-temperature annealing at 350°C for preparation; and the coating has poor light transmittance, only about 70%.

[0006] Regarding the report on doping modification of titanium dioxide, Zhang Pu applied for a modified nano titanium dioxide self-cleaning coating and its preparation method in 2016 (patent application publication number: CN106380981B). The coating uses silanized boron nitrogen doping to modify nano titanium dioxide, which is dispersed in a mixture of acrylic monomers, emulsifiers, water and initiators to obtain a modified nano titanium dioxide self-cleaning coating. The coating needs to be calcined at high temperature, and the preparation process conditions are harsh. In 2018, Zhang Shufen et al. applied for a titanium dioxide-organic composite self-cleaning coating with high transmittance and lasting super hydrophilicity and a mild preparation method thereof (patent application publication number: CN109593390B). The titanium dioxide modified with alcohol amine in the coating is directly dispersed in acrylic monomers, and then spin-coated and cured with ultraviolet light to obtain a titanium dioxide-organic composite coating. The cost of UV lamp curing of the coating is relatively high; and the spin coating process is only suitable for small substrates and cannot be mass-produced.

[0007] Regarding the report on the composite of titanium dioxide and other inorganic materials, Sun Zaicheng et al. reported a transmittance-enhancing super-hydrophilic zinc oxide / titanium dioxide composite nanostructure self-cleaning coating and its preparation method in 2014 (patent application publication number: CN103922802B). The coating contact angle is about 10°, and it needs to be calcined at 400°C, and the preparation process conditions are harsh; the coating spin coating process cannot be mass-produced. In 2022, Zhu Hongjun reported a super-hydrophilic coating material composition and its application method (patent application publication number: CN114381149A). The coating uses nano-titanium dioxide and nano-silicon dioxide as two components to form a super-hydrophilic self-cleaning coating. Although the coating performance is good, the preparation process cycle is too long.

[0008] In recent years, super-hydrophilic self-cleaning coatings have developed rapidly and have broad application prospects in photovoltaics, biomedicine, anti-fouling and other fields. However, the current commercial super-hydrophilic self-cleaning coatings have low transmittance, complex preparation process, long preparation cycle and high energy consumption, which are not suitable for large-scale production. Therefore, it is of great application value to develop super-hydrophilic coating materials that are easy to prepare, can be mass-produced, have high transparency and excellent self-cleaning properties. Summary of the invention

[0009] In view of this, in order to solve this problem, the object of the present invention is to provide a highly transparent super hydrophilic coating and a preparation method thereof.

[0010] In order to achieve the above object, the present invention adopts the following technical solution:

[0011] The first object of the present invention is to provide a method for preparing a highly transparent super-hydrophilic coating, comprising the following steps:

[0012] The inorganic material is uniformly dispersed in a solvent at room temperature, and then an organic hydrophilic polymer is added to be uniformly dispersed; then an anionic surfactant is added to disperse to obtain a suspension; the prepared suspension is dip-coated and pulled on a glass sheet for molding, and then dried at room temperature to obtain the highly transparent super hydrophilic coating.

[0013] Optionally, the inorganic material is titanium dioxide; the organic hydrophilic polymer is an acrylic ester monomer, specifically including a combination of one or more of hydroxyethyl methacrylate and hydroxyethyl acrylate; the anionic surfactant is sodium α-olefin sulfonate; and the solvent is a combination of one or more of water, ethanol, isopropanol, and butanol.

[0014] Furthermore, the mass ratio of the solvent to titanium dioxide is 1:(0.005-0.02); the mass ratio of the solvent to the acrylate monomer is 1:(0.005-0.02); and the mass ratio of the solvent to the anionic surfactant is 1:(0.0035-0.05).

[0015] Optionally, the inorganic material is stirred in a solvent for 1 to 2 hours and then dispersed evenly; then an organic hydrophilic polymer is added and magnetically stirred for 1 to 2 hours to be evenly dispersed; then an anionic surfactant is added, magnetically stirred for 2 to 4 hours, and ultrasonically dispersed for 20 to 40 minutes to obtain a suspension; the prepared suspension is dip-coated and pulled on a cleaned glass sheet at a speed of 1 to 2 mm / s to form a mold, and dried at room temperature to obtain the highly transparent super hydrophilic coating.

[0016] It should be noted that in the present invention, the coating can have certain photocatalytic activity and hydrophilicity by introducing titanium dioxide; acrylate monomers and sodium α-olefin sulfonate help to further improve the hydrophilicity, surface energy and film-forming property of the coating. The prepared coated glass has a light transmittance of 91.8%, which is suitable for equipment with high requirements for light transmittance; the static water contact angle is only 2.8°, which can achieve a stable super-hydrophilic state; it can catalytically decompose organic pollutants adsorbed on the surface of the coating under ultraviolet light, and has an excellent self-cleaning effect. The present invention can achieve the simple and efficient preparation of a super-hydrophilic self-cleaning coating with ultra-high transparency and excellent photocatalytic activity at room temperature.

[0017] The second object of the present invention is to provide a highly transparent super hydrophilic coating prepared by the method as described above, wherein the maximum light transmittance of the coating is 91% to 92% and the static water contact angle is 2 to 5°.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention coats a layer of coating on the glass through a simple dipping process, and makes the glass surface have a super-hydrophilic effect without the need for illumination, with a hydrophilic angle of <5° and a light transmittance of up to 91.8%.

[0020] 2. The dip-coating-pulling preparation method is simple to operate and has high coating preparation efficiency. The coating prepared by this method has good uniformity, high repeatability and low cost.

[0021] 3. The suspension prepared by the present invention can be prepared at any time at the construction site, which simplifies the coating preparation process and has higher flexibility, feasibility and economic benefits in actual production.

[0022] 4. The preparation process of the present invention is simple, and only requires the steps of suspension preparation, dipping, and drying. The required mechanical equipment and process flow are mature, which can meet the needs of different usage scenarios and has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0024] Figure 1 Schematic diagram of the static water contact angle of the coating surface in a typical embodiment of the present invention.

[0025] Figure 2 The present invention is a flow chart of the method for preparing the super-hydrophilic coating on the glass surface disclosed in the present invention.

[0026] Figure 3 Static water contact angles of bare glass and the highly transparent super hydrophilic self-cleaning coating prepared in Example 1.

[0027] Figure 4 The transmittance curves of bare glass and the highly transparent super hydrophilic self-cleaning coating prepared in Example 1 are shown.

[0028] Figure 5 This is a diagram showing the ultraviolet photocatalytic degradation of adsorbed methylene blue pollutants by the highly transparent super hydrophilic self-cleaning coating prepared in Example 1.

[0029] Figure 6 Static water contact angles of bare glass and the highly transparent super hydrophilic self-cleaning coating prepared in Example 2.

[0030] Figure 7 The transmittance curves of bare glass and the highly transparent super hydrophilic self-cleaning coating prepared in Example 2.

[0031] Figure 8 Static water contact angles of bare glass and the highly transparent super hydrophilic self-cleaning coating prepared in Example 3.

[0032] Fig. 9 The transmittance curves of bare glass and the highly transparent super hydrophilic self-cleaning coating prepared in Example 3 are shown.

[0033] Fig.10 Static water contact angles of bare glass and the highly transparent super hydrophilic self-cleaning coating prepared in Example 4.

[0034] Fig.11 The transmittance curves of bare glass and the highly transparent super hydrophilic self-cleaning coating prepared in Example 4 are shown.

[0035] Fig.12 This is a graph showing the ultraviolet photocatalytic degradation of adsorbed methylene blue pollutants by uncoated glass in comparative example 1. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.

[0038] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0039] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

[0040] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be combined arbitrarily, and the resulting technical solutions belong to the contents disclosed in the embodiments of the present application.

[0041] The invention discloses a highly transparent super-hydrophilic coating and a preparation method thereof.

[0042] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0043] Example 1

[0044] A room temperature preparation method for a highly transparent super-hydrophilic self-cleaning coating comprises the following steps:

[0045] (1) Clean the glass substrate by placing the glass sheet in a beaker and ultrasonically cleaning it with anhydrous ethanol and deionized water for 20 min in sequence. After cleaning, place the glass sheet in an oven to dry for later use.

[0046] (2) Under room temperature, titanium dioxide is magnetically stirred for 1 to 2 hours and uniformly dispersed in isopropanol, wherein the particle size of titanium dioxide nanoparticles is 5 to 30 nm and the content in isopropanol is 1 wt %;

[0047] (3) Under room temperature, hydroxyethyl methacrylate is magnetically stirred for 1 to 2 hours to be uniformly dispersed in step 2, wherein the content of hydroxyethyl methacrylate in isopropanol is 1 wt %;

[0048] (4) adding sodium α-olefin sulfonate to the mixed solution obtained in step 3, magnetically stirring for 2 to 4 hours, and ultrasonically dispersing for 20 to 40 minutes, and uniformly dispersing in step 3, wherein the content of sodium α-olefin sulfonate in isopropanol is 0.45 wt %;

[0049] (5) The suspension obtained in step 4 is coated on a clean glass sheet by a dip-coating-pulling method, and dried at room temperature.

[0050] The prepared super-hydrophilic coating has a transmittance of 91.8%, a water contact angle of 2.8°, and can completely degrade organic pollutants under ultraviolet light within 120 minutes.

[0051] Example 2

[0052] A room temperature preparation method for a highly transparent super-hydrophilic self-cleaning coating comprises the following steps:

[0053] (1) Clean the glass substrate by placing the glass sheet in a beaker and ultrasonically cleaning it with anhydrous ethanol and deionized water for 20 min in sequence. After cleaning, place the glass sheet in an oven to dry for later use.

[0054] (2) Under room temperature, titanium dioxide is magnetically stirred for 1 to 2 hours and uniformly dispersed in isopropanol, wherein the particle size of titanium dioxide nanoparticles is 25 nm and the content in isopropanol is 1 wt %;

[0055] (3) Under room temperature, hydroxyethyl methacrylate is magnetically stirred for 1 to 2 hours to be uniformly dispersed in step 2, wherein the content of hydroxyethyl methacrylate in isopropanol is 0.5 wt %;

[0056] (4) adding sodium α-olefin sulfonate to the mixed solution obtained in step 3, stirring magnetically for 2 to 4 hours, and ultrasonically dispersing for 20 to 40 minutes, and uniformly dispersing the sodium α-olefin sulfonate in step 3 to a content of 0.35 wt % in isopropanol;

[0057] (5) The suspension obtained in step 4 is coated on a clean glass sheet by a dip-coating-pulling method, and dried at room temperature.

[0058] The prepared super-hydrophilic coating has a light transmittance of 91.6% and a water contact angle of 4.1°.

[0059] Example 3

[0060] A room temperature preparation method for a highly transparent super-hydrophilic self-cleaning coating comprises the following steps:

[0061] (1) Clean the glass substrate by placing the glass sheet in a beaker and ultrasonically cleaning it with anhydrous ethanol and deionized water for 20 min in sequence. After cleaning, place the glass sheet in an oven to dry for later use.

[0062] (2) Under room temperature, titanium dioxide is magnetically stirred for 1 to 2 hours and uniformly dispersed in isopropanol, wherein the particle size of titanium dioxide nanoparticles is 25 nm and the content in isopropanol is 1.5 wt %;

[0063] (3) Under room temperature, hydroxyethyl methacrylate is magnetically stirred for 1 to 2 hours to be uniformly dispersed in step 2, wherein the content of hydroxyethyl methacrylate in isopropanol is 0.5 wt %;

[0064] (4) adding sodium α-olefin sulfonate to the mixed solution obtained in step 3, stirring magnetically for 2 to 4 hours, and ultrasonically dispersing for 20 to 40 minutes, and uniformly dispersing the sodium α-olefin sulfonate in step 3 to a content of 0.5 wt % in isopropanol;

[0065] (5) The suspension obtained in step 4 is coated on a clean glass sheet by a dip-coating-pulling method, and dried at room temperature.

[0066] The prepared super-hydrophilic coating has a light transmittance of 91.3% and a water contact angle of 3.9°.

[0067] Example 4

[0068] A room temperature preparation method for a highly transparent super-hydrophilic self-cleaning coating comprises the following steps:

[0069] (1) Clean the glass substrate by placing the glass sheet in a beaker and ultrasonically cleaning it with anhydrous ethanol and deionized water for 20 min in sequence. After cleaning, place the glass sheet in an oven to dry for later use.

[0070] (2) Under room temperature, titanium dioxide is magnetically stirred for 1 to 2 hours and uniformly dispersed in isopropanol, wherein the particle size of titanium dioxide nanoparticles is 25 nm and the content in isopropanol is 1 wt %;

[0071] (3) Under room temperature, hydroxyethyl methacrylate is magnetically stirred for 1 to 2 hours to be uniformly dispersed in step 2, wherein the content of hydroxyethyl methacrylate in isopropanol is 0.25 wt %;

[0072] (4) adding sodium α-olefin sulfonate to the mixed solution obtained in step 3, stirring magnetically for 2 to 4 hours, and ultrasonically dispersing for 20 to 40 minutes, and uniformly dispersing the sodium α-olefin sulfonate in step 3 to a content of 0.4 wt % in isopropanol;

[0073] (5) The suspension obtained in step 4 is coated on a clean glass sheet by a dip-coating-pulling method, and dried at room temperature.

[0074] The prepared super-hydrophilic coating has a light transmittance of 91.4% and a water contact angle of 3.6°.

[0075] In order to further demonstrate the beneficial effects of the present invention and to better understand the present invention, the following comparative examples and experimental examples are used to further illustrate the technical features disclosed in the present invention, but they should not be understood as limiting the present invention. Other improvements made by those skilled in the art based on the above invention content without creative work are also considered to fall within the scope of protection of the present invention.

[0076] Comparative Example 1

[0077] Cleaned glass substrate without coating.

[0078] The four types of coated glasses prepared in Examples 1-4 and the uncoated glass in Comparative Example 1 were subjected to light transmittance tests and water contact angle tests; the coated glass obtained in Example 1 and the uncoated glass in Comparative Example 1 were subjected to an "organic pollutant degradation" experiment to verify the self-cleaning effect.

[0079] Performance Characterization

[0080] The schematic diagram of the static water contact angle of the coated glass sheet after the treatment of steps (1) to (5) in Examples 1, 2, 3 and 4 is as follows: Figure 3 , 6 , 8 and 10.

[0081] Depend on Figure 3It can be seen that when 10 μL of pure water is added to the surface of the coating prepared in Example 1, the static water contact angle of the droplet is 2.8°; Figure 6 It can be seen that the static water contact angle of the coating surface prepared in Example 2 is 4.1°; Figure 8 It can be seen that the static water contact angle of the coating surface prepared in Example 3 is 3.9°; Fig.10 It can be seen that the static water contact angle of the coating surface prepared in Example 4 is 3.6°. Compared with the water contact angle of 57.5° on the bare glass surface in Comparative Example 1, the coated glass surface has the static water contact angle required for super hydrophilicity, so that surface impurities such as dust can be washed away by water, making the glass surface have a self-cleaning function.

[0082] The light transmittance curves of the coated glass sheets after being treated in steps (1) to (5) in Examples 1, 2, 3 and 4 are shown in FIG. Figure 4 , 7 , 9 and 11.

[0083] As can be seen from the figure, the prepared coating is coated on the glass surface, and the light transmittance of the coating is higher than that of the bare glass substrate in comparative example 1, with a maximum light transmittance of 91.8%. After the coating is prepared, the light transmittance of the bare glass surface increases, which can be well applied to equipment requiring high light transmittance.

[0084] Figure 5 This is a diagram showing the ultraviolet photocatalytic degradation of adsorbed methylene blue pollutants by the highly transparent super hydrophilic self-cleaning coating prepared in Example 1; Fig.12 This is a graph of the ultraviolet light catalytic degradation of the adsorbed methylene blue pollutant by the uncoated glass of comparative example 1; as can be seen from the figure, after the adsorption of methylene blue, the sample exhibits an absorption peak near 610nm, and under the irradiation of a 6W ultraviolet lamp, the absorption peak of the coated glass gradually disappears, while the absorption peak of the bare glass does not disappear, indicating that the coating can catalytically decompose the organic matter adsorbed on the surface under ultraviolet light and has certain self-cleaning properties.

[0085] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a highly transparent super-hydrophilic coating, characterized in that: The steps include: The inorganic material is uniformly dispersed in a solvent at room temperature, an organic hydrophilic polymer is added and uniformly dispersed, and then an anionic surfactant is added and dispersed to obtain a suspension; the prepared suspension is dip-coated and pulled on a glass sheet for molding, and dried at room temperature to obtain the highly transparent super hydrophilic coating.

2. The method for preparing a highly transparent super-hydrophilic coating according to claim 1, characterized in that: The inorganic material is titanium dioxide; the organic hydrophilic polymer is an acrylic ester monomer, specifically including a combination of one or more of hydroxyethyl methacrylate and hydroxyethyl acrylate; the anionic surfactant is sodium α-olefin sulfonate; and the solvent is a combination of one or more of water, ethanol, isopropanol, and butanol.

3. The method for preparing a highly transparent super-hydrophilic coating according to claim 2, characterized in that: The mass ratio of the solvent to titanium dioxide is 1:(0.005-0.02); the mass ratio of the solvent to the acrylic ester monomer is 1:(0.005-0.02); and the mass ratio of the solvent to the anionic surfactant is 1:(0.0035-0.05).

4. The method for preparing a highly transparent super-hydrophilic coating according to claim 1, characterized in that: The inorganic material is stirred in a solvent for 1 to 2 hours and then dispersed evenly; then an organic hydrophilic polymer is added and magnetically stirred for 1 to 2 hours to disperse evenly; then an anionic surfactant is added, magnetically stirred for 2 to 4 hours, and ultrasonically dispersed for 20 to 40 minutes to obtain a suspension; the prepared suspension is dip-coated and pulled on a cleaned glass sheet at a speed of 1 to 2 mm / s to make a mold, and dried at room temperature to obtain the highly transparent super hydrophilic coating.

5. A highly transparent super hydrophilic coating prepared by the method of claim 1, characterized in that: The maximum light transmittance of the coating is 91% to 92%, and the static water contact angle is 2 to 5 degrees.

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