High-temperature-resistant super-spreading paint and method for preparing coating based on paint

Abstract

The invention discloses a high-temperature-resistant super-spreading coating and a method for preparing a coating based on the high-temperature-resistant super-spreading coating. The high-temperature-resistant super-spreading coating is prepared by mixing the following components in parts by mass: 5 to 10 parts of chained silicon dioxide sol, 5 to 10 parts of spherical silicon dioxide sol, 0.5 to 1 part of titanium dioxide, 0.2 to 0.5 part of halloysite nanotube, 1 to 2 parts of porous silicon dioxide isopropanol dispersion liquid, 1 to 2 parts of inorganic binder and 80 to 90 parts of water. Substances with different surface tensions, such as water, saline water, ethanol and soybean oil, are selected for testing the surface of a coating formed by the coating, the measured static contact angles are close to 0 degree, and the spreading time is less than 1s; after the formed coating is subjected to high-temperature-resistant tests at different temperatures of 200 DEG C, 400 DEG C, 600 DEG C, 800 DEG C and the like, the coating still keeps excellent super-hydrophilic and super-spreading characteristics.

Description

TECHNICAL FIELD

[0001] The present application relates to a high-temperature-resistant super-spreading coating, and a method for preparing a coating based on the coating. BACKGROUND

[0002] Recently, the extremely fast complete spreading process of liquid droplets has been defined as super-spreading rather than the classic super-hydrophilic concept, that is, the super-spreading time of a liquid droplet is < 1 s, and the dynamic spreading behavior of a 2 μl liquid droplet is driven by surface tension rather than gravity. The inherent hydrophilicity of a high-surface-energy surface is the most basic prerequisite for the surface to achieve super-spreading, and the microchannels and nano-rough structures further guide and accelerate the propulsion process of the three-phase contact line, significantly increasing the spreading flux and spreading speed of the liquid. The synergistic control of the multi-level micro-nano structure and the high-surface-energy component of the surface can easily and quickly achieve the complete super-spreading of different liquid droplets on the surface, and therefore the super-spreading interface can be widely used in heat dissipation, microfluid transport, micro-chemical reactors, and other fields involving intelligent liquid operation.

[0003] At present, most super-spreading micro-nano surfaces with excellent performance are composed of organic matter, transition metal compounds, laser patterned surfaces, or hydrogels rich in high-energy groups. They are easy to modify, have substrate universality, and are easy to control accurately. However, they also have the disadvantages of fragile structure, easy loss of hydrophilic groups, complex preparation process, and dependence on specific surface topological structure, which cannot achieve high-temperature-resistant super-hydrophilic super-spreading effect, limiting their application in complex high-temperature conditions in actual working conditions. SUMMARY

[0004] The present application aims to provide a high-temperature-resistant super-spreading coating that can solve the problem of a significant decrease in hydrophilicity caused by the destruction of micro-nano structure components on the surface of existing super-spreading coatings due to high-temperature complex working conditions. Another object of the present application is to provide a method for preparing a coating based on the above-mentioned coating, which makes the formed coating have good hydrophilicity.

[0005] Technical solution: The high-temperature-resistant super-spreading coating according to the present application is prepared by mixing the following components in the following mass fractions: 5-10 parts of chain silica sol, 5-10 parts of spherical silica sol, 0.5-1 part of titanium white, 0.2-0.5 part of halloysite nanotubes, 1-2 parts of porous silica isopropanol dispersion, 1-2 parts of inorganic binder, and 80-90 parts of water.

[0006] In the formula system of the coating of the present application, the nanoparticles with gradient particle size are selected, the particle size of chain silica is 10-20 nm; the particle size of spherical silica is 40-80 nm; the particle size of titanium white powder is 100 nm; the particle size of porous silica is 120-150 nm; the tube diameter of halloysite nanotube is 30-50 nm, and the tube length is 200-500 nm.

[0007] The solid content of the chain silica sol is 15 wt.%, and the particle size of the chain silica is 10-20 nm; the solid content of the spherical silica sol is 15 wt.%, and the particle size of the spherical silica is 40-80 nm; the solid content of the porous silica isopropanol dispersion solution is 15 wt.%, and the particle size of the porous silica (in a hollow porous structure) is 100-150 nm.

[0008] The halloysite nanotube is prepared by the following method: 30-50 parts by mass of halloysite nanotube with a tube diameter of 30-50 nm and a tube length of 0.5-2 μm is added to 100-150 parts by mass of pure water, which is stirred uniformly at room temperature, and then placed in a cell crusher for 4 h of crushing, and then dried and ground into powder to obtain nanotube with a tube length of 200-500 nm.

[0009] The inorganic binder is prepared by the following method: 50-80 parts by mass of phosphoric acid is added to 20-50 parts by mass of pure water for constant temperature heating and stirring, the water bath stirring temperature is 90 °C, then 10-20 parts by mass of aluminum hydroxide (powder) is added until the solution is clear, and then 0.2-0.5 parts by mass of ferric chloride (powder) is added, and stirred until a light yellow clear solution is obtained, to obtain the inorganic binder (iron ion complex aluminum phosphate salt).

[0010] The preparation method of the above-mentioned high-temperature-resistant super-spreading coating is as follows: the formula amount of chain silica sol, spherical silica sol, titanium white powder, halloysite nanotube and porous silica isopropanol dispersion solution is uniformly dispersed in water, ultrasonic dispersion is carried out for 15-30 min, then the formula amount of inorganic binder is added, and after mixing uniformly under water bath heating, the high-temperature-resistant super-spreading coating is obtained; wherein the pH of the coating is 4-6.

[0011] In the formula, the silica sol and the iron ion complex aluminum phosphate salt provide an acidic environment. Water is used as a solvent, and three inorganic nanoparticles, namely, silica, titanium dioxide, and halloysite nanotubes, are selected, which have a large number of hydroxyl groups on the surface and a gradient particle size. The self-aggregation characteristics of the inorganic nanoparticles are used to form island-shaped nanostructures with high surface activity, which maximizes the wettability of the super-spreading coating constructed. Further, the hydroxyl groups on the inorganic nanomaterials are used to complex and adsorb the iron ion complex aluminum phosphate salt, forming a more rough and dense metal anchoring inorganic bonding network, which improves the film stability of the coating formed. In addition, the isopropanol component in the porous silica isopropanol dispersion can also adjust the surface tension of the solvent, effectively improving the dispersibility and compatibility of the coating, so that each component is uniformly bonded together in the coating system through chemical bonds, improving the cohesion and uniformity of the coating formed, and further improving the high-temperature stability of the coating, which still has good super-hydrophilic performance at high temperature.

[0012] The method for forming a high-temperature-resistant super-spreading coating based on the above high-temperature-resistant super-spreading coating includes the following steps:

[0013] (1) Activating the cleaned substrate: The substrate is first decontaminated with anhydrous ethanol and butyl acetate (ultrasonic cleaning for 15 min with anhydrous ethanol and butyl acetate, respectively), and then immersed in a mixed solution of water and concentrated hydrochloric acid for 1-3 min, taken out, washed with water, and dried for standby use.

[0014] (2) The high-temperature-resistant super-spreading coating is coated on the surface of the substrate treated in step (1) by immersion coating, spraying, rolling, or scraping, and after low-temperature baking and high-temperature annealing, a high-temperature-resistant super-spreading coating is obtained.

[0015] In step (1), the substrate is one of steel, copper, silicon wafer, ceramic, or glass. The volume ratio of the mixture of concentrated hydrochloric acid and water is 0.08:999.80, and the mass concentration of concentrated hydrochloric acid is 0.003%.

[0016] In step (2), the low-temperature baking condition is heating at 50-100℃ for 6-8h. The low-temperature baking can promote the stable form of the self-aggregated inorganic nanoparticles and the multi-dimensional complex network structure, and can improve the hydrophilic performance of the subsequent coating after 6-8h of low-temperature baking at 50-100℃. The high-temperature annealing condition is 600-800℃ under argon protection for 2h. The high-temperature annealing process can promote the transformation of the inorganic binder aluminum phosphate salt to a higher adhesive aluminum phosphate salt and aluminum titanium phosphate salt, so that the binder is integrated with the coating components, and further produces good bonding force with the substrate, so that the coating surface has excellent high-temperature resistance and super-spreading performance.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The present invention adopts a variety of inorganic nanoparticles with rich hydroxyl groups on the surface, and utilizes their intrinsic spontaneous agglomeration characteristics and the high-temperature stable adhesion of inorganic binders to spontaneously form a high-surface-energy pure inorganic coating with rough island-shaped nanostructures and micron-scale amorphous channels on the substrate, thereby effectively solving the limitations of traditional super-hydrophilic coating surfactant loss, carbonization failure of organic components under high-temperature conditions, and dependence of traditional super-spreading coatings on surface topology; (2) The coating surface formed by the coating of the present invention is tested with substances with different surface tensions, such as water, salt water, ethanol, and soybean oil, and the measured static contact angles are all close to 0°, and the spreading time is all less than 1s; after the formed coating is subjected to high-temperature resistance tests at different temperatures such as 200, 400, 600, and 800°C, the coating still maintains excellent super-hydrophilic and super-spreading properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The reaction mechanism of the hydrolysis process of the inorganic binder aluminum phosphate prepared in Example 1;

[0019] Figure 2 This is a diagram of the complex anchoring mechanism of iron ion complex anchoring aluminum phosphate obtained in Example 1;

[0020] Figure 3 The transmission electron microscope structure diagram of the original nanotubes is the tube length and diameter;

[0021] Figure 4 A diagram showing the formation process of the super-spreading coating of the present invention and the principle of the coating forming a coating;

[0022] Figure 5 The super-spreadable coating obtained in Example 1, a powder-baking scanning electron microscope image, and the particle size data of the particles suspended in the coating;

[0023] Figure 6 This is a high-speed camera instantaneous image of the water droplet spreading process of the super-spreading coating prepared in Example 1;

[0024] Figure 7 The surface atomic force microscope (AFM) rough structure of the super-spreading coating prepared in Example 1

[0025] Figure 8 The data of surface functional groups of the super-spreading coating prepared in Example 1 were obtained by infrared spectroscopy before and after high-temperature annealing;

[0026] Figure 9 The thermogravimetric data analysis results of the super-spreading coating prepared in Example 1 during high-temperature annealing;

[0027] Figure 10 The XRD data composition analysis results of the low-temperature curing and high-temperature annealing processes of the super-spreading coating prepared in Example 1;

[0028] Figure 11 Instantaneous video of droplet transport performance comparison between original substrate and super-spreading coating prepared in Example 1; wherein a is original substrate; b is super-spreading coating prepared in Example 1;

[0029] Figure 12 Scanning electron microscope surface morphology of coating prepared in Examples 1-6;

[0030] Figure 13 Scanning electron microscope surface morphology of coating prepared in Example 1 after high temperature of 800℃. DETAILED DESCRIPTION

[0031] Example 1

[0032] The preparation method of the high-temperature-resistant super-spreading coating of the present application comprises the following steps:

[0033] (1) 10 parts by mass of chain silica sol (solid content of chain silica sol is 15 wt.%, particle size of chain silica is 10-20 nm), 10 parts by mass of spherical silica sol (solid content of spherical silica sol is 15 wt.%, particle size of spherical silica is 40-80 nm), 0.5 parts by mass of titanium white powder (particle size of titanium white powder is 100 nm), 0.2 parts by mass of halloysite nanotube with a tube length of 200-500 nm, and 1 part by mass of porous silica isopropanol dispersion (solid content of porous silica isopropanol dispersion is 15 wt.%, particle size of porous silica is 100-150 nm) are uniformly dispersed in 80 parts by mass of water, cell disruption is performed using a fine bubble disrupter for 2 h, and then ultrasonic dispersion is performed for 30 min to obtain a slurry;

[0034] (2) 2 parts by mass of inorganic binder and 96 parts by mass of the slurry prepared in step (1) are mixed, and uniform stirring is performed at 60℃ constant temperature water bath and 700 rpm for 3 h to obtain a high-temperature-resistant super-spreading coating.

[0035] The inorganic binder is prepared by the following method: 60 parts by mass of 99 wt.% phosphoric acid is added dropwise into 50 parts by mass of pure water, constant temperature heating and stirring are performed, the water bath stirring temperature is 90℃, and then 15.6 parts by mass of aluminum hydroxide powder is slowly added thereto until the solution is clear, and the inorganic binder hydrolysis process is as follows: Figure 1The aluminum phosphate salt molecules in the reaction system are promoted to transform into ceramic at high temperature, and a dehydration condensation reaction occurs to generate a macromolecular crosslinked network structure with aluminum phosphate as the skeleton. In this process, the modified nanoparticles can be fully embedded in the developed network and tightly combined together through chemical bonding between the surface remaining hydroxyl groups and the aluminum phosphate salt. Then, 0.2 parts by mass of iron trichloride powder is continuously added, and the mixture is stirred at 80°C under water bath heating for 8h to obtain a light yellow clear solution, thereby obtaining the inorganic binder. The chemical shift value of the complex of the Fe(III)-phosphate system mainly depends on the number of phosphate groups directly coordinated with Fe(III). When the water molecules in the Fe(III) ligand field are replaced by phosphate groups, the complexing effect is almost additive, as shown in Figure 2 .

[0036] The halloysite nanotubes are prepared by the following method: 30 parts by mass of original halloysite nanotubes with a tube diameter of 30-50nm and a tube length of 0.5-2μm, as shown in Figure 3 , are added to 100 parts by mass of pure water for treatment, and stirred uniformly at room temperature. Then, the mixture is placed in a cell crusher for crushing for 4h, and then dried and ground into powder to form nanotubes with a tube length of 200-500nm.

[0037] The method for forming a high-temperature-resistant super-spreading coating based on the above super-spreading coating includes the following steps:

[0038] (1) The cleaned substrate is subjected to activation treatment: the glass substrate is first subjected to decontamination treatment with anhydrous ethanol and butyl acetate (ultrasonic cleaning with anhydrous ethanol and butyl acetate for 15min), and then placed in a mixed solution of water and concentrated hydrochloric acid, soaked for 1-3min, and then taken out. The volume ratio of the mixed solution of concentrated hydrochloric acid and water is 0.08:999.80, and the mass concentration of the concentrated hydrochloric acid is 0.003%. The glass substrate is washed with water and dried for standby use.

[0039] (2) The super-spreading coating is coated on the glass substrate treated in step (1) in the form of dip coating, and then placed in a blast oven for baking at 100°C for 6h, and then placed in a tube furnace for high-temperature annealing at 600°C for 2h, thereby obtaining a high-temperature-resistant super-spreading coating.

[0040] The schematic diagram of the coating formation mechanism in Example 1 is shown in Figure 4 . Different particle size silica sol particles with high surface activity, high water stability and large adsorption volume spontaneously surround the surfaces of titanium dioxide and halloysite nanotubes to form a stable, tough and high-surface-energy super-spreading layer.

[0041] The coating prepared in Example 1 is a milky white liquid (suspension). The powder drying and liquid particle size analysis are as shown in Figure 5As shown, the particles in the suspension are obviously aggregated, with an average particle size of 486.1 nm. In combination with the particle size of the gradient inorganic filler, it can be seen that the inorganic structure is spontaneously aggregated into a more stable inorganic structure during the preparation of the coating; and the presence of isopropyl alcohol and inorganic binder components changes the surface energy of the original solution system, making the solution dispersion more stable. After testing, the solution remained stable and did not settle within 7 days. Figure 6 As shown, the super-spreading performance of the coating, a 2-microliter droplet can quickly spread to <5° in 73 ms, and to 0° in 438 ms, showing excellent super-hydrophilic super-spreading performance. While Figure 7 As shown, the coating surface is smooth and dense, with a surface roughness of Rq = 87.2 nm. Figure 8 As shown, after 600℃ high-temperature annealing, the coating surface is rich in hydroxyl groups, which helps to build the super-hydrophilic surface of the coating. Ti-O-Si bonds and Si-O-Si bonds are detected, indicating that SiO2 and TiO2 are combined through hydroxyl groups. Since halloysite is a mineral component, it is difficult to judge the combination mechanism from the infrared spectrum. Figure 9 As shown, the thermogravimetric results show that there is a composition change at ~235℃, which is consistent with the critical temperature of isopropyl alcohol decomposition; and the subsequent weight loss and heat release may be related to the dehydration and recrystallization process. Figure 10 As shown, the X-ray diffraction analysis results of the coating composition change after 100℃ low-temperature curing and 600℃ high-temperature annealing show that after high-temperature curing, part of the aluminum phosphate salt is combined with inorganic components to form more solid aluminum-silicon-titanium salt and titanium phosphate salt, etc., realizing good combination of inorganic binder and inorganic particles, and thus providing good protection for the durability of the coating. Figure 11 As shown, the original substrate and the droplet transport process on the formed coating surface show that the droplet on the original substrate surface is difficult to detach due to the low surface energy of the substrate, while the droplet on the coating surface can quickly detach from the surface, leaving a thin droplet tail, which will also quickly evaporate in the following time. Figure 12 As shown, the coating surfaces prepared in Examples 1-6 are uniformly distributed with a large number of island-shaped large particle structures, and other areas are also completely covered with a large number of inorganic nanoparticles that have not completed island-shaped aggregation. Figure 13 As shown, after 800℃ high-temperature treatment of the coating of Example 1, the coating still maintains a good modified form with an intact overall structure. After testing, the static contact angle is measured to be 0°, and the 2-microliter droplet spreading time is 450 ms, showing no attenuation in super-hydrophilic and super-spreading performance. In addition, other substances with different surface tensions, including salt water, ethanol, and soybean oil, were tested, and the static contact angles were all measured to be 0°, while the spreading times were 508 ms, 1024 ms, and 4000 ms, respectively. It can be seen that the super-spreading coating prepared in Example 1 has good liquid affinity.

[0042] The overall hardness change before and after modification is characterized using a Vickers hardness tester, the surface hardness of the copper plate substrate is 58.5 Hv, the super-spreading coating is formed on the copper plate substrate by using the above method of forming a coating on a glass substrate, the overall hardness of the coating-copper plate substrate is 62.2 Hv, and therefore the super-spreading coating prepared by the application has good adhesion. The adhesion change of the coating in harsh environments is simulated by sand water erosion test, the sample (coating-copper plate substrate) is fixed on the wall of a 2L beaker by a clamp, and the coating surface is immersed in sand water (sand particle size: 100-250 μm, sand content: 4 g / L), and the sand water is stirred at a speed of 5000 r / min by using a disc dispersion type mechanical stirrer, so that the linear shear speed of the sand water reaches about 30 m / s, the coating surface is eroded, and the super-hydrophilicity of the coating is gradually lost after 20 min.

[0043] Example 2

[0044] A preparation method of a coating, comprising the following steps:

[0045] (1) 20 parts by mass of spherical silica sol (solid content of the spherical silica sol is 15 wt.%, particle size of the spherical silica is 40-80 nm), 0.5 parts by mass of titanium white (particle size of the titanium white is 100 nm), 0.2 parts by mass of halloysite nanotubes with a tube length of 200-500 nm, and 1 part by mass of porous silica isopropanol dispersion liquid (solid content of the porous silica isopropanol dispersion liquid is 15 wt.%, particle size of the porous silica is 100-150 nm) are uniformly dispersed in 80 parts by mass of water, cell disruption is performed by using a fine bubble disrupter for 2 h, and then ultrasonic dispersion is performed for 30 min to obtain a slurry;

[0046] (2) 2 parts by mass of an inorganic binder and 96 parts by mass of the slurry prepared in step (1) are mixed, and uniform stirring is performed at 60°C in a constant temperature water bath and at 700 revolutions / minute for 3 h to obtain a coating.

[0047] The inorganic binder is prepared by the following method: 60 parts by mass of 99 wt.% phosphoric acid is added dropwise into 50 parts by mass of pure water, constant temperature heating and stirring are performed, then 15.6 parts by mass of aluminum hydroxide powder is slowly added into the solution until the solution is clear, then 0.2 parts by mass of ferric chloride powder is continuously added into the solution, stirring is performed under the condition of 80°C water bath heating for 8 h to obtain a light yellow clear solution, and the inorganic binder is obtained.

[0048] The halloysite nanotubes are prepared by the following method: 30 parts by mass of halloysite nanotubes with a tube diameter of 30-50 nm and a tube length of 0.5-2 μm are added into 100 parts by mass of pure water, uniform stirring is performed at room temperature, then cell disruption is performed in a cell disrupter for 4 h, and then drying and grinding are performed to form nanotubes with a tube length of 200-500 nm.

[0049] A method for forming a coating layer based on the above coating, comprising the following steps:

[0050] (1) The cleaned substrate is activated: the glass substrate is first cleaned with anhydrous ethanol and butyl acetate (ultrasonic cleaning for 15 min with anhydrous ethanol and butyl acetate respectively), then the substrate is placed in a mixed solution of water and concentrated hydrochloric acid, soaked for 1-3 min, then taken out, wherein the volume ratio of the mixed solution of concentrated hydrochloric acid and water is 0.08:999.80, the mass concentration of concentrated hydrochloric acid is 0.003%, and then washed with water and dried for standby;

[0051] (2) The coating is coated on the glass substrate treated in step (1) by dip coating, first placed in a blast oven and baked at 100°C for 6h, then placed in a tube furnace and annealed at 600°C for 2h to obtain a coating layer.

[0052] Since the fillers of the coating layer of Example 2 are all composed of spherical inorganic particles, it is difficult to form a uniform and stable island-like composite structure on the surface of the coating layer, but rather a larger particle structure is attached to the surface, as shown in Figure 12 Due to the insufficient number of hydroxyl groups on the nano-structured surface, the measured hydrophilic contact angle is about 8°, which can still maintain super-hydrophilicity, but cannot reach the optimal super-spreading state of 0°. At the same time, due to the formation of higher and more disordered micron channels, the liquid drop flow resistance is increased, and the high-temperature super-spreading performance of the coating layer of Example 1 is significantly reduced. The surface spreading time of a 2 microliter liquid drop after high-temperature test at 800°C increases to 830ms.

[0053] Example 3

[0054] A method for preparing a coating, comprising the following steps:

[0055] (1) 20 parts by mass of chain silica sol (the solid content of the chain silica sol is 15 wt.%, and the particle size of the chain silica is 10-20 nm), 0.5 parts by mass of titanium white (the particle size of the titanium white is 100 nm), 0.2 parts by mass of halloysite nanotubes with a tube length of 200-500 nm, and 1 part by mass of porous silica isopropanol dispersion (the solid content of the porous silica isopropanol dispersion is 15 wt.%, and the particle size of the porous silica is 100-150 nm) are uniformly dispersed in 80 parts by mass of water, first subjected to cell disruption for 2h with a fine bubble disruptor, and then subjected to ultrasonic dispersion for 30 min to obtain a slurry;

[0056] (2) 2 parts by mass of an inorganic binder and 96 parts by mass of the slurry prepared in step (1) are mixed, and uniformly stirred at 60°C in a constant temperature water bath and at 700 revolutions per minute for 3h to obtain a coating.

[0057] The preparation method of the inorganic binder and the halloysite nanotubes is the same as that in Embodiments 1-2.

[0058] The method for forming a coating layer based on the coating comprises the following steps:

[0059] (1) Activating the cleaned substrate: the glass substrate is first cleaned with anhydrous ethanol and butyl acetate (ultrasonic cleaning for 15 min with anhydrous ethanol and butyl acetate respectively), and then the substrate is placed in a mixed solution of water and concentrated hydrochloric acid, soaked for 1-3 min, and then taken out, wherein the volume ratio of the mixed solution of concentrated hydrochloric acid and water is 0.08:999.80, and the mass concentration of the concentrated hydrochloric acid is 0.003%; the substrate is washed with water and dried for standby;

[0060] (2) The coating is applied to the glass substrate treated in step (1) by dip coating, and then the glass substrate is placed in a blast oven and baked at 100°C for 6 h, and then placed in a tube furnace and annealed at 600°C for 2 h to obtain a coating layer.

[0061] Due to the large amount of spherical silica skeleton missing in the coating of Example 3, the island-shaped particles on the surface of the coating layer collapse obviously, and the surface roughness Rq of the coating layer is reduced to 43 nm. As shown in FIG. 4, the surface of the coating layer is covered with chain-shaped nanoparticles and halloysite nanotubes scattered on the surface. Due to the failure to form good micro-nano channels, the liquid drop spreading time is prolonged, and the spreading time of a 2-μl liquid drop is 680 ms. After testing, the final-state hydrophilic contact angle is 5°. After 800°C high-temperature testing, the spreading time of a 2-μl liquid drop is 1240 ms, which is difficult to achieve the best super-spreading. Figure 12 Example 4

[0062] A method for preparing a coating, comprising the following steps:

[0063] (1) 10 parts by mass of chain-shaped silica sol (the solid content of the chain-shaped silica sol is 15 wt.%, and the particle size of the chain-shaped silica is 10-20 nm), 10 parts by mass of spherical silica sol (the solid content of the spherical silica sol is 15 wt.%, and the particle size of the spherical silica is 40-80 nm), 0.5 parts by mass of titanium white (the particle size of the titanium white is 100 nm), and 0.2 parts by mass of halloysite nanotubes with a length of 200-500 nm are uniformly dispersed in 80 parts by mass of water, and then subjected to cell disruption with a fine bubble disruptor for 2 h, and then ultrasonic dispersion for 30 min to obtain a slurry;

[0064] (2) 2 parts by mass of an inorganic binder and 96 parts by mass of the slurry prepared in step (1) are mixed, and then stirred uniformly at 60°C in a constant-temperature water bath and at 700 rpm for 3 h to obtain a coating.

[0065] ​

[0066] The preparation methods of the inorganic binder and halloysite nanotubes are the same as those in Example 1.

[0067] The method for forming a coating based on the above-mentioned coating comprises the following steps:

[0068] (1) Activating the cleaned substrate: First, decontaminate the glass substrate with anhydrous ethanol and butyl acetate (ultrasonic cleaning with anhydrous ethanol and butyl acetate for 15 minutes respectively), then place the substrate in a mixed solution of water and concentrated hydrochloric acid, soak for 1 to 3 minutes, and then take it out. The mixed volume ratio of concentrated hydrochloric acid to water is 0.08:999.80; the mass concentration of concentrated hydrochloric acid is 0.003%; rinse with water, dry and set aside;

[0069] (2) The coating is applied to the glass substrate treated in step (1) by dipping, first placed in a blast oven at 100° C. for 6 h, and then placed in a tube furnace for annealing at 600° C. for 2 h to obtain a coating.

[0070] Due to the lack of isopropyl alcohol in the coating of Example 4, the surface tension of the solution is higher, making it difficult for the inorganic particles to be fully dispersed and causing obvious agglomeration and sedimentation. At the same time, the coating showed slight powdering and whitening, resulting in a significant decrease in adhesion. The coating became loose and porous due to the reduction in cross-linking strength. Figure 12 As shown, a large number of particles are aggregated, with the halloysite nanotube particle morphology more prominent. Testing showed that the spreading time of a 2-microliter droplet on the coating of Example 4 increased to 3 seconds, with significant droplet pinning. The final water contact angle was approximately 10°, indicating a loss of super-spreading. Even after high-temperature testing at 800°C, the coating still failed to cause the droplet to spread.

[0071] Example 5

[0072] A method for preparing a coating comprises the following steps:

[0073] (1) 10 parts by mass of chain silica sol (solid content of chain silica sol is 15 wt.%, particle size of chain silica is 10-20 nm), 10 parts by mass of spherical silica sol (solid content of spherical silica sol is 15 wt.%, particle size of spherical silica is 40-80 nm), 0.2 parts by mass of halloysite nanotubes with a tube length of 200-500 nm, and 1 part by mass of porous silica isopropanol dispersion (solid content of porous silica isopropanol dispersion is 15 wt.%, particle size of porous silica is 100-150 nm) are uniformly dispersed in 80 parts by mass of water, firstly subjected to cell disruption by a fine bubble disruptor for 2 h, and then subjected to ultrasonic dispersion for 30 min to obtain a slurry;

[0074] (2) 2 parts by mass of an inorganic binder and 96 parts by mass of the slurry prepared in step (1) were mixed, and the mixture was stirred uniformly for 3 h in a constant temperature water bath at 60° C. and 700 rpm to obtain a coating.

[0075] The preparation methods of the inorganic binder and halloysite nanotubes are the same as those in Example 1.

[0076] The method for forming a coating based on the above-mentioned coating comprises the following steps:

[0077] (1) Activating the cleaned substrate: First, decontaminate the glass substrate with anhydrous ethanol and butyl acetate (ultrasonic cleaning with anhydrous ethanol and butyl acetate for 15 minutes respectively), then place the substrate in a mixed solution of water and concentrated hydrochloric acid, soak for 1 to 3 minutes, and then take it out. The mixed volume ratio of concentrated hydrochloric acid to water is 0.08:999.80; the mass concentration of concentrated hydrochloric acid is 0.003%; rinse with water, dry and set aside;

[0078] (2) The coating is applied to the glass substrate treated in step (1) by dipping, first placed in a blast oven at 100° C. for 6 h, and then placed in a tube furnace for annealing at 600° C. for 2 h to obtain a coating.

[0079] Since the coating of Example 5 has the same situation as Example 3, namely the lack of accumulation of large particle skeletons and the loss of surface hydroxyl groups, the original island structure and micro-nano channels of the coating are collapsed. Figure 12 As shown, a large number of particles adhere to the surface, forming a texture. Furthermore, the lack of titanium dioxide prevents the coating from forming titanium phosphate with the inorganic binder at high temperatures, resulting in insufficient adhesion and partial detachment from the substrate. The water contact angle on the coating surface increases to 15°, and the coating loses its superhydrophilic and superspreading properties.

[0080] Example 6

[0081] A method for preparing a coating comprises the following steps: uniformly dispersing 10 parts by mass of chain silica sol (solid content of the chain silica sol is 15 wt.%, and particle size of the chain silica is 10-20 nm), 10 parts by mass of spherical silica sol (solid content of the spherical silica sol is 15 wt.%, and particle size of the spherical silica is 40-80 nm), 0.5 parts by mass of titanium dioxide (particle size of the titanium dioxide is 100 nm), 0.2 parts by mass of halloysite nanotubes with a tube length of 200-500 nm, and 1 part by mass of porous silica isopropanol dispersion (solid content of the porous silica isopropanol dispersion is 15 wt.%, and particle size of the porous silica is 100-150 nm) in 80 parts by mass of water; first, performing cell disruption with a fine bubble disruptor for 2 h, and then performing ultrasonic dispersion for 30 min to obtain the coating.

[0082] wherein the inorganic binder is prepared according to the method of Example 1.

[0083] The method for forming a coating layer based on the coating described above comprises the following steps:

[0084] (1) Activation treatment of the cleaned substrate: the glass substrate is first subjected to decontamination treatment with anhydrous ethanol and butyl acetate (ultrasonic cleaning with anhydrous ethanol and butyl acetate for 15 min each), then the substrate is placed in a mixed solution of water and concentrated hydrochloric acid, soaked for 1-3 min and then taken out, wherein the volume ratio of the mixed solution of concentrated hydrochloric acid and water is 0.08:999.80, and the mass concentration of the concentrated hydrochloric acid is 0.003%; the substrate is washed with water and dried for standby use;

[0085] (2) The super-spreading coating is coated on the glass substrate treated in step (1) by dip coating, and then the substrate is first baked in a blast oven at 100°C for 6 h, and then annealed at a high temperature of 600°C for 2 h in a tube furnace to obtain a coating layer.

[0086] Due to the absence of high-temperature bonding between the components of the coating layer of Example 6, the adhesion and the cohesion of the coating layer are both decreased, which leads to the fact that the coating layer can be easily scratched off by fingerprints. The particles on the surface of the coating layer are easily detached, and the basic structural stability is lost. The measured water contact angle on the surface is 0°, but this is a non-reproducible result obtained on the basis of the dissolution and loss of the surface components, which leads to the loss of integrity of the coating layer. The surface structure of the coating layer is shown in FIG. 6, wherein a large number of particles on the surface of the coating layer are accumulated, and an ideal micro-nano structure is not formed. The formed coating layer loses the super-hydrophilic and super-spreading properties at high temperature. Figure 12

[0087] Example 7

[0088] The only difference between Example 7 and Example 1 is that the preparation method of the inorganic binder is different (no iron ions are added), and the specific method is as follows:

[0089] (1) 10 parts by mass of chain silica sol (the solid content of the chain silica sol is 15 wt.%, and the particle size of the chain silica is 10-20 nm), 10 parts by mass of spherical silica sol (the solid content of the spherical silica sol is 15 wt.%, and the particle size of the spherical silica is 40-80 nm), 0.5 parts by mass of titanium white (the particle size of the titanium white is 100 nm), 0.2 parts by mass of halloysite nanotubes with a tube length of 200-500 nm, and 1 part by mass of porous silica isopropyl alcohol dispersion (the solid content of the porous silica isopropyl alcohol dispersion is 15 wt.%, and the particle size of the porous silica is 100-150 nm) are uniformly dispersed in 80 parts by mass of water, and then subjected to cell crushing with a fine bubble crusher for 2 h, followed by ultrasonic dispersion for 30 min to obtain a slurry;

[0090] ​(2) 2 parts by mass of inorganic binder and 96 parts by mass of the slurry prepared in step (1) are mixed, and stirred uniformly at 60°C in a constant-temperature water bath at 700 rpm for 3 h to obtain a coating.

[0091] The inorganic binder is prepared by the following method: 60 parts by mass of 99 wt.% phosphoric acid is added dropwise to 50 parts by mass of pure water, and heated and stirred at a constant temperature, with the water bath stirring temperature being 90°C, and then 15.6 parts by mass of aluminum hydroxide powder is slowly added thereto until the solution is clear, to obtain the inorganic binder.

[0092] The halloysite nanotubes are prepared by the following method: 30 parts by mass of halloysite nanotubes with a tube diameter of 30-50 nm and a tube length of 0.5-2 μm are added to 100 parts by mass of pure water, and stirred uniformly at room temperature, and then placed in a cell crusher for 4 h, and then dried and ground into powder to form nanotubes with a tube length of 200-500 nm.

[0093] The method for forming a coating layer based on the coating comprises the following steps:

[0094] (1) The cleaned substrate is activated: the glass substrate is first decontaminated with anhydrous ethanol and butyl acetate (ultrasonic cleaning for 15 min with anhydrous ethanol and butyl acetate respectively), and then placed in a mixed solution of water and concentrated hydrochloric acid, soaked for 1-3 min, and then taken out, wherein the volume ratio of the mixed solution of concentrated hydrochloric acid and water is 0.08:999.80, and the mass concentration of the concentrated hydrochloric acid is 0.003%; and then washed with water, dried, and used as needed;

[0095] (2) The coating is coated on the glass substrate treated in step (1) by dip coating, and then placed in a forced air oven and baked at 100°C for 6 h, and then placed in a tube furnace and annealed at 600°C for 2 h to obtain a coating layer.

[0096] Example 7 does not use ferric ions to further complex the inorganic components, resulting in a coating with weaker adhesion relative to the adhesion after complexation. A slight scratch test using a finger shows obvious scratches. Morphology measurement shows that the island-like agglomerated particles at the micro-nano interface are reduced, and more loose nano particles are dispersed on the surface, forming a state of large particles and small particles distributed alternately. The measured surface static water contact angle is 0°, and the 2 μl water droplet spreading time is 892 ms.

[0097] Example 8

[0098] Example 8 differs from Example 1 only in that there is no low-temperature baking step in the process of forming the coating, specifically:

[0099] (1) 10 parts by mass of chain silica sol (solid content of the chain silica sol is 15 wt.%, particle size of the chain silica is 10-20 nm), 10 parts by mass of spherical silica sol (solid content of the spherical silica sol is 15 wt.%, particle size of the spherical silica is 40-80 nm), 0.5 parts by mass of titanium white (particle size of the titanium white is 100 nm), 0.2 parts by mass of halloysite nanotube with a tube length of 200-500 nm, 1 part by mass of porous silica isopropanol dispersion (solid content of the porous silica isopropanol dispersion is 15 wt.%, particle size of the porous silica is 100-150 nm) are uniformly dispersed in 80 parts by mass of water, cell disruption is performed using a fine bubble disrupter for 2 h, and then ultrasonic dispersion is performed for 30 min to obtain a slurry;

[0100] (2) 2 parts by mass of an inorganic binder and 96 parts by mass of the slurry prepared in step (1) are mixed, and uniform stirring is performed at 60°C in a constant temperature water bath and at 700 rpm for 3 h to obtain a coating.

[0101] The inorganic binder and the halloysite nanotube are prepared according to the method of Example 1.

[0102] The method for forming a coating layer based on the above coating includes the following steps:

[0103] (1) The substrate after cleaning treatment is subjected to activation treatment: the glass substrate is first subjected to decontamination treatment using anhydrous ethanol and butyl acetate (ultrasonic cleaning using anhydrous ethanol and butyl acetate for 15 min, respectively), and then the substrate is placed in a mixed solution of water and concentrated hydrochloric acid, soaked for 1-3 min, and then taken out, wherein the volume ratio of the mixed solution of concentrated hydrochloric acid and water is 0.08:999.80, and the mass concentration of the concentrated hydrochloric acid is 0.003%; the substrate is washed with water and dried for standby use;

[0104] (2) The coating is applied to the glass substrate after step (1) by dip coating, and is annealed at a high temperature of 600°C for 2 h in a tube furnace to obtain a coating layer.

[0105] Since Example 8 is not subjected to low-temperature curing and drying after the coating layer is prepared, the coating layer not only undergoes morphology remodeling and interface reaction during high-temperature annealing, but also loses a large amount of water. This results in that the surface bonding force of the coating layer is not strong, and the inorganic particles cannot be closely agglomerated and coagulated. It is determined that a large number of micropores and cracks are generated on the surface of the coating layer, and the surface contact angle is 23°, which shows poor coating and hydrophilicity, and the super-spreading property cannot be achieved at all.

[0106] Example 9

[0107] The only difference between Example 9 and Example 1 is that the low-temperature baking time during the formation of the coating layer is 3 h, and the specific process is as follows:

[0108] (1) 10 parts by mass of chain silica sol (solid content of chain silica sol is 15 wt.%, particle size of chain silica is 10-20 nm), 10 parts by mass of spherical silica sol (solid content of spherical silica sol is 15 wt.%, particle size of spherical silica is 40-80 nm), 0.5 parts by mass of titanium white (particle size of titanium white is 100 nm), 0.2 parts by mass of halloysite nanotube with length of 200-500 nm, 1 part by mass of porous silica isopropanol dispersion (solid content of porous silica isopropanol dispersion is 15 wt.%, particle size of porous silica is 100-150 nm) are uniformly dispersed in 80 parts by mass of water, cell disruption is performed by a fine bubble disrupter for 2 h, and then ultrasonic dispersion is performed for 30 min to obtain a slurry;

[0109] (2) 2 parts by mass of inorganic binder and 96 parts by mass of the slurry prepared in step (1) are mixed, and uniform stirring is performed at 60°C in a constant temperature water bath and at 700 rpm for 3 h to obtain a coating.

[0110] The preparation method of the inorganic binder and the halloysite nanotube is the same as in Example 1.

[0111] The method for forming a coating layer based on the above coating includes the following steps:

[0112] (1) The cleaned substrate is subjected to activation treatment: the glass substrate is first subjected to decontamination treatment with anhydrous ethanol and butyl acetate (ultrasonic cleaning with anhydrous ethanol and butyl acetate for 15 min, respectively), and then the substrate is placed in a mixed solution of water and concentrated hydrochloric acid, soaked for 1-3 min, and then taken out, wherein the volume ratio of the mixed solution of concentrated hydrochloric acid and water is 0.08:999.80, and the mass concentration of the concentrated hydrochloric acid is 0.003%; the substrate is washed with water and dried for standby use;

[0113] (2) The coating is coated on the glass substrate treated in step (1) in a manner of dip coating, and then the glass substrate is first placed in a blast oven and baked at 100°C for 3 h, and then placed in a tube furnace and annealed at a high temperature of 600°C for 2 h to obtain a coating layer.

[0114] Since the low-temperature curing time is shortened in Example 9, the coating layer fails to be fully subjected to solvent drying, and a large amount of free water and adsorbed water molecules remain, which can combine with the hydroxyl groups on the surface of the inorganic particles, thereby blocking the inorganic reaction in the high-temperature sintering process within the specified time, resulting in that the particles on the surface of the coating layer are not combined tightly enough, and a large amount of micropores and cracks are also generated, although the amount of the cracks is less than that in Example 8, but the overall coating property of the coating layer is still damaged. In addition, it is determined that the water contact angle on the surface of the coating layer is 15°, which shows that the coating layer formed without sufficient drying and curing not only is difficult to achieve the super-spreading property, but also is difficult to achieve the super-hydrophilic effect.

Claims

1. A high temperature resistant super spreadable coating, characterized in that: The invention is prepared by mixing the following components in parts by mass: 5 to 10 parts of chain silica sol, 5 to 10 parts of spherical silica sol, 0.5 to 1 part of titanium dioxide, 0.2 to 0.5 parts of halloysite nanotubes, 1 to 2 parts of porous silica isopropanol dispersion, 1 to 2 parts of inorganic binder and 80 to 90 parts of water.

2. The high temperature resistant super spreadable coating according to claim 1, characterized in that: The solid content of the chain silica sol is 15-16 wt.%, and the particle size of the chain silica is 10-20 nm; the solid content of the spherical silica sol is 15-16 wt.%, and the particle size of the spherical silica is 40-80 nm.

3. The high temperature resistant super spreadable coating according to claim 1, characterized in that: The solid content of the porous silicon dioxide isopropanol dispersion is 15-16 wt.%, the particle size of the porous silicon dioxide is 100-150 nm, and the particle size of the titanium dioxide is 100-105 nm.

4. The high temperature resistant super spreadable coating according to claim 1, characterized in that: The diameter of halloysite nanotubes is 30 to 50 nm, and the length is 200 to 500 nm.

5. The high temperature resistant super spreadable coating according to claim 1, characterized in that: The inorganic binder is prepared by the following method: 50 to 80 parts by mass of phosphoric acid are added to 20 to 50 parts by mass of pure water, and the mixture is heated and stirred at a constant temperature. Then, 10 to 20 parts by mass of aluminum hydroxide are slowly added thereto until the solution is clear. Then, 0.2 to 0.5 parts by mass of ferric chloride are added thereto, and the mixture is stirred until a clear solution is obtained, thereby obtaining the inorganic binder.

6. The method for preparing the high temperature resistant super spreadable coating according to claim 1, characterized in that: Specifically, the formulated amount of chain silica sol, spherical silica sol, titanium dioxide, halloysite nanotubes and porous silica isopropanol dispersion are uniformly dispersed in water, ultrasonically dispersed, and then the formulated amount of inorganic binder is added thereto. After mixing in a water bath, a high-temperature resistant super-spreading coating is obtained; wherein the pH value of the coating is 4 to 6.

7. A method for forming a high temperature resistant super spreading coating based on the coating according to claim 1, characterized in that: The steps include: (1) Activating the cleaned substrate: Decontaminating the substrate with anhydrous ethanol and butyl acetate, then placing the substrate in a mixed solution of water and concentrated hydrochloric acid, soaking it, taking it out, rinsing it with water, and drying it; (2) applying the high temperature resistant super spread coating to the surface of the substrate treated in step (1) by dipping, spraying, roller coating or scraping, and obtaining the high temperature resistant super spread coating after low temperature baking and high temperature annealing.

8. The method for forming a high temperature resistant super spread coating according to claim 7, wherein: In step (1), the substrate is one of steel, copper, silicon wafer, ceramic or glass.

9. The method for forming a high temperature resistant super spread coating according to claim 7, wherein: In step (1), the mixing volume ratio of concentrated hydrochloric acid and water is 0.08:999.80-1000; the mass concentration of concentrated hydrochloric acid is 0.003-0.004%.

10. The method for forming a high temperature resistant super spread coating according to claim 7, wherein: In step (2), the low-temperature baking condition is heating at 50-100° C. for 6-8 hours; the high-temperature annealing condition is keeping warm at 600-800° C. under inert gas protection for 2-2.5 hours.

Images