CN114752236A

CN114752236A - High-reflection wear-resistant super-hydrophobic coating and preparation method thereof

Info

Publication number: CN114752236A
Application number: CN202210412869.1A
Authority: CN
Inventors: 王艳艳; 唐兴杰; 彭长四; 刘暑
Original assignee: Suzhou University
Current assignee: Suzhou University
Priority date: 2022-04-19
Filing date: 2022-04-19
Publication date: 2022-07-15
Anticipated expiration: 2042-04-19
Also published as: CN114752236B; WO2023201943A1

Abstract

The invention discloses a high-reflection wear-resistant super-hydrophobic coating and a preparation method thereof. Use of Room temperature vulcanized Silicone Rubber (RTV) and Tetraethylorthosilicate (TEOS) for the treatment of GCC microparticles and TiO₂The nano particles are subjected to surface modification to obtain modified GCC/TiO₂The suspension liquid is used for preparing a high-reflection wear-resistant super-hydrophobic coating on the surface of cement by a simple spraying process, and has excellent super-hydrophobicity, the static Contact Angle (CA) of the coating is 158 degrees, the rolling angle (SA) of the coating is 5.6 degrees, excellent sunlight reflection characteristics are shown, and the reflectivity is up to 89.2 percent. In addition, the coating has excellent wear resistance and durability, and can maintain super-hydrophobicity after being rubbed on the surface of 800-mesh sandpaper by a 500 g weight or being stripped by a tape for 50 times. The coating can not only withstand the corrosion of acid and alkali solutions and the long-term ultraviolet radiation (168 h), but also exhibitsExcellent self-cleaning performance and frost resistance.

Description

High-reflection wear-resistant super-hydrophobic coating and preparation method thereof

Technical Field

The invention belongs to a coating technology, and particularly relates to a high-reflection wear-resistant super-hydrophobic coating and a preparation method thereof.

Background

In hot summer, the temperature of the building is increased by solar radiation, so that the energy consumption demand of building refrigeration is increased sharply, and thus global energy is consumed in large quantities. Meanwhile, excessive use of primary energy causes an aggravation of greenhouse effect and destruction of global ecological environment. Therefore, the reduction of the energy consumption of building refrigeration has important significance for energy conservation and emission reduction. At present, a large number of experimental researches prove that the high-reflectivity coating can reduce the temperature of the outer wall and the roof of a building, the sunlight reflectivity of the white coating which is carefully designed in the prior art is up to 87.9 percent, and the temperature of the surface of cement can be effectively reduced, however, the white coating used outdoors is easily polluted by dust or soil in the environment, and the sunlight reflectivity of the white coating is sharply reduced. Although the solar reflectance of the coating can be restored after manual cleaning, manual cleaning is costly and unsafe and can also wear the surface of the solar reflective coating. Therefore, there is a need to develop a solar reflective coating having a self-cleaning function.

Research shows that the micro-nano coarse structure of the super-hydrophobic coating is easily damaged in an outdoor environment. In order to improve the mechanical stability of the superhydrophobic coating, a great deal of intensive research work is done by the scholars. Shen et al prepared a superhydrophobic coating with excellent mechanical stability by spraying 1H, 2H-perfluorodecyltriethoxysilane modified carbon nanotubes and silica filler onto a polyurethane-containing aluminum substrate by a spray coating process. Yu and the like firstly spray a Polydopamine (PDA) solution on substrates of various materials by a two-step spraying method, and then spray hydrophobic nano-silica particles on the PDA to prepare the wear-resistant super-hydrophobic coating with chemical stability and self-repair. Currently, although great progress has been made in the preparation of abrasion resistant superhydrophobic coatings, abrasion resistant superhydrophobic coatings with solar light reflecting properties are still less studied.

Disclosure of Invention

The invention provides aThe simple, environment-friendly and easy-to-prepare method takes ground limestone (GCC) as a main raw material and titanium dioxide (TiO)₂) For the solar reflection enhancing filler, room temperature vulcanized silicone Rubber (RTV) and tetraethyl orthosilicate (TEOS) are used for hydrophilic GCC microparticles and TiO ₂The nano particles are subjected to surface modification, a high-reflection wear-resistant super-hydrophobic coating is prepared on the surface of the cement by adopting a spraying method, tests such as mechanical stability, chemical stability, ultraviolet resistance, frost resistance and the like are carried out on the coating, and the coating shows excellent wear resistance and durability and has potential application value.

The invention adopts the following technical scheme:

a high-reflectivity antiwear super-hydrophobic coating is prepared from modified GCC/TiO₂Drying the suspension to obtain the suspension; the modified GCC/TiO₂The suspension comprises ground calcium carbonate, titanium dioxide, room temperature vulcanized rubber and tetraethyl orthosilicate.

The high-reflection wear-resistant super-hydrophobic material consists of a substrate and a coating positioned on the substrate, wherein the coating is the high-reflection wear-resistant super-hydrophobic coating and is prepared from modified GCC/TiO₂Drying the suspension to obtain the suspension; the modified GCC/TiO₂The suspension comprises ground calcium carbonate, titanium dioxide, room temperature vulcanized rubber and tetraethyl orthosilicate.

In the invention, titanium dioxide powder, heavy calcium carbonate powder, room temperature vulcanized rubber, tetraethyl orthosilicate, ammonia water and water are mixed to obtain modified GCC/TiO₂A suspension; preferably, titanium dioxide powder is added into water, heavy calcium carbonate powder is added, tetraethyl orthosilicate, room temperature vulcanized rubber and ammonia water are added, and modified GCC/TiO is obtained ₂And (3) suspension.

In the present invention, the mass ratio of the ground calcium carbonate to the titanium dioxide is (1 to 10) to 1, preferably (1.5 to 7) to 1, and more preferably (2 to 5) to 1. The super-hydrophobic coating has a plurality of unique performances such as oil-water separation, self-cleaning, corrosion prevention, antibiosis and the like, so that the super-hydrophobic coating is widely concerned by scientific researchers. The research finds that the excellent hydrophobicity of the super-hydrophobic coating is determined by the specific micro-nano rough structure and the low surface energy substance on the surface. At present, most of super-hydrophobic coatings have the problems of high price of raw materials, complex preparation process, high toxicity of chemical reagents and the like, and the practical application of the super-hydrophobic coatings is severely restricted due to poor durability and insufficient stability of the super-hydrophobic coatings. Aiming at the problems, heavy calcium carbonate (GCC) is selected as a main raw material, and the durable super-hydrophobic coating which is low in cost, simple and environment-friendly in preparation process, capable of being produced in a large scale and has different functional characteristics is designed and developed.

According to the invention, the mass sum of the heavy calcium carbonate and the titanium dioxide, the dosage ratio of the tetraethyl orthosilicate, the room-temperature vulcanized rubber and the ammonia water is 8g to (1-3) mL to (0.2-0.8) mL, and the preferred dosage ratio is 8g to (1.5-2.5) mL to (0.3-0.6) mL.

In the invention, the substrate is a conventional material, can be an inorganic material or an organic material, and preferably, the substrate is a cement substrate. The invention tests and analyzes various performances of the super-hydrophobic coating, details the actual application of the durable super-hydrophobic coating, and provides certain reference and guidance significance for realizing industrialization of the super-hydrophobic coating.

In the invention, modified GCC/TiO is adopted₂And spraying the suspension on a substrate, and drying to obtain the high-reflection wear-resistant super-hydrophobic material. The specific spraying and drying are conventional technologies, for example, a high-reflection wear-resistant super-hydrophobic coating can be obtained on the surface of the substrate after the substrate is placed at room temperature. Preferably, the thickness of the high-reflection wear-resistant super-hydrophobic coating is micron-sized, such as 100-500 microns, and further 200-400 microns.

The preparation method of the super-hydrophobic surface has made great progress and development, however, the realization of large-scale production and wide application has a long distance, mainly because of the problems of poor durability, complex preparation process, expensive chemical reagent, high toxicity and the like of the super-hydrophobic surface. The invention selects cheap Ground Calcium Carbonate (GCC) as a main raw material, and prepares two durable super-hydrophobic coatings with different functional characteristics by adding auxiliary raw materials with different components and adopting a simple, environment-friendly and easily industrialized method. And testing various performances of the super-hydrophobic coating Practical application of the durable super-hydrophobic coating is researched in detail, and certain reference and guidance significance is provided for realizing industrialization of the super-hydrophobic coating. The invention combines GCC and TiO₂Mixing the components according to a certain proportion, and carrying out surface modification on the components by room temperature vulcanized silicone Rubber (RTV) and tetraethyl orthosilicate (TEOS) to obtain modified GCC/TiO₂The suspension adopts a simple spraying process to prepare the high-reflection wear-resistant super-hydrophobic coating on the cement surface. The prepared high-reflection wear-resistant super-hydrophobic coating shows excellent super-hydrophobicity, the static Contact Angle (CA) of the coating is 158 degrees, the rolling angle (SA) of the coating is 5.6 degrees, the super-hydrophobic coating with the sunlight reflectivity of 89.2 percent is obtained, and the surface temperature of the coating can be reduced by 10 ℃ compared with that of a common cement coating under the direct sunlight of the outdoor environment temperature of 35 ℃. The coating shows excellent wear resistance and durability, can be loaded with 500 g weight, and can be rubbed on the surface of 800-mesh sand paper for 200 cm or repeatedly torn and adhered by an adhesive tape for 50 times, and can also bear the corrosion of strong acid and strong alkaline solution for a long time and the ultraviolet radiation of 168 h, and still keeps good super-hydrophobicity. The coating shows excellent self-cleaning performance and frost resistance, has rejection effect on common liquid in life such as cola, coffee, muddy water and the like, and can keep super-hydrophobicity for a long time in a low-temperature severe environment.

Drawings

FIG. 1 shows different GCC and TiO₂Coating surface SEM topography map coating of mass ratio: (a) s1, (b) coating S2, (c) coating S3, (d) coating S4, and (e) coating S5; (f) is the CA and SA plots for coatings S1-S5.

FIG. 2 shows (a) TiO₂GCC and modified GCC/TiO₂FT-IR spectrum of the coating; (b) GCC and modified GCC/TiO₂XPS spectra of the coating.

FIG. 3 is a graph of (a) reflectance spectra of different coatings; (b) ultraviolet region, visible region, near infrared region and sunlight average reflectivity graph of different coatings; (c) solar radiation patterns of different coatings under outdoor conditions; (d) the change of the surface temperature of different coatings along with the change of the solar radiation time.

FIG. 4 is a schematic diagram of (a) a tape peel test; (b) a coating surface hydrophobic effect graph after 10 peeling cycles; (c) the effect of the number of stripping cycles on the coating surfaces CA and SA.

FIG. 5 is (a) a schematic diagram of a wear test; (b) a hydrophobic effect graph of the coating surface after 10 abrasion cycles; (c) effect of wear cycle number on coating surfaces CA and SA.

FIG. 6 is SEM images of the high-reflection wear-resistant super-hydrophobic coating at different magnifications before and after wear: (a) before the coating is abraded; (d) and (e) and (f) are after the coating is abraded.

FIG. 7 is a schematic diagram of (a) droplets of different pH on the surface of the coating; (b) a CA plot of the lower surface of the coating in contact with droplets of different PH; (c) a schematic representation of the coating's resistance to ultraviolet radiation; (d) the effect of the irradiation period of the uv light on the CA and SA of the coating.

FIG. 8 is (a) a mixture of soil, lime and gravel and (b) a self-cleaning process of tomato paste on the surface of a highly reflective wear-resistant super-hydrophobic coating; (c) the high-reflection wear-resistant super-hydrophobic coating has the effect of repelling various common liquid drops (blue ink, honey, muddy water, saline water, coffee and cola).

FIG. 9 is a process of water drop freezing on the surface of (a) a common cement coating and (b) a high-reflection wear-resistant super-hydrophobic coating; (c) graph of variation of CA and SA of a highly reflective abrasion resistant superhydrophobic coating over an icing-deicing test cycle.

Detailed Description

The super-hydrophobic surface has a plurality of unique properties and is paid much attention by researchers, and in recent decades, with the continuous forward progress of scientific research, the super-hydrophobic surface shows huge application prospects in a plurality of fields such as self-cleaning, corrosion resistance, oil-water separation, antibiosis and the like, and new applications in more fields can be developed in the future. At present, a plurality of methods for preparing the super-hydrophobic surface are available, such as an electrostatic spinning method, a photoetching method, a sol-gel method, an etching method, a chemical vapor deposition method and the like, and the performance of the prepared super-hydrophobic surface is greatly improved. However, there is a certain distance for large-scale industrial production of the superhydrophobic surface, mainly because the preparation process is complicated, the cost is high, the environment is polluted, and the like, and most of the reasons are limited to laboratory preparation, and the prepared superhydrophobic surface has poor durability, and the superhydrophobicity of the superhydrophobic surface is reduced or even lost if the superhydrophobic surface is exposed to corrosive environment or ultraviolet radiation for a long time. In addition, the mechanical stability, self-cleaning properties and color monotonicity of the superhydrophobic surface also affect the practical application of the superhydrophobic coating. Aiming at the problems, the invention has the significance that the preparation process of the super-hydrophobic coating is simpler, environment-friendly, lower in cost and more durable in performance, and can be widely applied to various industries.

The invention uses GCC microparticles and TiO₂The combination of the nano particles is used as sunlight reflection enhanced filler, and the high-reflection wear-resistant super-hydrophobic coating is prepared by combining an environment-friendly hydrophobic modification preparation method and adopting a simple spraying method. The super-hydrophobic coating with high solar reflectivity is obtained, and the surface temperature of the cement coating can be effectively reduced by the coating. The hard cement base material is used as a bridge between the bonding coating and the substrate, so that the wear resistance of the coating is improved. In addition, the coating has low preparation cost, can be produced in large scale, and can be widely applied to building outer walls.

Sample testing and characterization

And (6) testing temperature change. The temperature change of the coating surface was measured using an infrared thermometer (DM-5002, China). The temperature was measured at six different locations on the surface for each sample, the results were arithmetically averaged and the single measurement was kept within 3 ℃ of the mean.

And (5) testing mechanical stability. The mechanical stability of the superhydrophobic coating was evaluated by a sandpaper abrasion test and a tape peeling test. In the sand paper abrasion test, 800-mesh sand paper is horizontally placed on a table, then one surface of a sample with a super-hydrophobic coating is tightly attached to the sand paper in a downward mode, and a 500 g weight is loaded on the sample to push the sample along a straight line. The moving speed of the sample was 5 cm/s and the moving distance was 20 cm, and then CA and SA on the surface of the coating layer were measured. In the tape stripping test, a special test tape was adhered to the surface of the superhydrophobic coating and a 1 kg weight was placed on the tape for 5 min, the weight was removed and the tape was peeled off, and the CA and SA of the coating surface were measured.

And (5) testing chemical stability. Selecting hydrochloric acid (HCL) and sodium hydroxide (NaOH) solutions to prepare corrosive aqueous solutions with pH values of 2-12, dripping corrosive liquids with different pH values on the surface of the coating, standing for 12 h, removing the liquid on the surface of the coating, drying for a period of time, and measuring CA and SA on the surface of the coating.

And (5) ultraviolet ray resistance test. A portable ultraviolet detection lamp is used as an ultraviolet radiation light source, the wavelength of output ultraviolet is 365 nm, and the power is 8W. The samples were irradiated for 12 h for one period, the samples were 5 cm perpendicular to the uv lamp source, and the CA and SA of the coating were measured after each irradiation period.

And (6) self-cleaning testing. Firstly, the prepared super-hydrophobic coating is placed in a glass ware in an inclined mode at a certain angle (10 degrees), a mixture of soil, lime and gravel is sprinkled on the surface of the coating, then deionized water is dripped from the upper portion of the coating, pollutants on the surface of the coating are taken away by water flow, and whether the pollutants on the surface of the super-hydrophobic coating are removed or not is observed by naked eyes.

And (4) frost resistance test. The prepared super-hydrophobic coating sample is placed in a freezing chamber with the temperature of-15 ℃, water drops of about 500 mu L are dripped on the surface of the sample, the appearance of the water drops in the icing process in a low-temperature environment is beaten at intervals, and the icing delaying performance of the sample is analyzed according to the appearance change of the water drops on the sample. And (3) placing the prepared super-hydrophobic coating into a freezing chamber, wherein the water content of water drops is about 50 mu L, taking out the sample and removing the frozen water drops after the water drops on the surface of the coating are completely frozen, and then measuring the change of the hydrophobicity of the surface of the coating so as to represent the mechanical stability of the freezing-deicing process of the sample.

EXAMPLE preparation of a highly reflective abrasion-resistant Superhydrophobic coating

Weighing TiO according to Table 1₂Putting the powder into a beaker, adding 15 mL of deionized water, magnetically stirring at 500 rpm/min for 10 min, adding GCC powder, and continuously magnetically stirring for 10 min; then 2 mL TEOS, 2 mL RTV and 0.5 mL ammonia water are added to continue magnetic stirring for 1 h at the stirring speedThe degree is 600 rpm/min, and finally the modified GCC/TiO is prepared₂And (3) suspension. Uniformly brushing cement (P.O52.5) on a clean acrylic plate, drying the surface, and then spraying a spray gun to modify GCC/TiO₂The suspension was sprayed on a cement substrate to a thickness of 300 μm and then left at room temperature for 12 hours until complete curing, to successfully prepare highly reflective abrasion-resistant superhydrophobic coatings, corresponding to S2-S5 in table 1.

Comparative example 1

Weighing 8 g of GCC powder, adding 15 mL of deionized water, magnetically stirring at 500 rpm/min for 20 min, adding 2 mL of TEOS, 2 mL of RTV and 0.5 mL of ammonia water, and continuing to magnetically stir for 1 h at the stirring speed of 600 rpm/min to finally prepare the modified GCC suspension. The reflective wear-resistant superhydrophobic coating was successfully prepared by uniformly brushing cement (p.o52.5) on a clean acrylic plate, drying the plate, spraying the modified GCC suspension on the cement substrate with a spray gun to a thickness of 300 μm, and then standing at room temperature for 12 hours until completely cured, corresponding to S1 in table 1.

Comparative example No. two

On the basis of example one (S3), without adding RTV, the resulting coating was hydrophilic.

GCC and TiO₂The mass ratio has a great influence on the wettability of the superhydrophobic coating, and in FIG. 1, (a) - (e) are different GCC and TiO₂SEM topography of coating surface by mass ratio, and (f) is a change graph of contact angle and sliding angle of the coating from S1 to S5. As can be seen from the figure, the super-hydrophobicity of the S2, S3, S4 and S5 coatings is better than that of the S1 coating, the content ratio of TiO2 in the S4 and S5 coatings is increased, the contact angle of the coatings is reduced, the rolling angle is increased slowly, and GCC and TiO are mixed₂The coating S3 with a mass ratio of 3: 1 had the best hydrophobic effect, with CA at 158 ℃ and SA at 5.6 ℃.

The chemical composition of the coating surface has a great influence on the hydrophobicity. Thus, TiO is treated by FT-IR and XPS₂GCC and GCC/TiO modified by RTV modification₂Coating (S3)The chemical composition analysis was performed, and the results are shown in fig. 2 (a). In the infrared absorption spectrum of GCC, the appearance was at 1394, 873 and 712cm^-1The absorption peaks at (B) represent the asymmetric stretching vibration, the in-plane bending vibration and the out-of-plane bending vibration of the C-O bond, respectively. In modified GCC/TiO ₂2964 cm in the infrared absorption spectrum of the coating^-1The absorption peak at (A) is the stretching vibration peak of the C-H bond. The absorption peak at 1259 cm-1 is due to Si-CH on RTV ₃Caused by stretching vibration. At 1020 cm^-1The absorption peak at (A) is caused by the asymmetric stretching of Si-O-Si. 798 cm^-1The absorption peak at (A) is a characteristic peak of Si (CH3) 2. In the XPS spectrum shown in fig. 2 (b), the presence of O, C and Ca elements in the original GCC was clearly observed. Compared with GCC, two new strong absorption peaks, namely Si 2s and Si 2p, appear in the coating spectrogram of GCC/TiO2 modified by RTV modification at the binding energy of 154 eV and 102 eV, wherein the carbon peak with the binding energy of 285eV is obviously enhanced due to a large amount of silicon elements and methyl groups in RTV, and the analysis shows that TiO is modified by RTV modification₂GCC was successfully modified by RTV modification.

And analyzing the reflection characteristics of the sunlight and the heat reflection performance. According to different wavelengths, solar radiation can be divided into an ultraviolet region, a visible region and a near infrared region, and the radiation energy of the visible region and the near infrared region accounts for more than 90% of the energy radiated by the sun. As shown in fig. 3(a), the reflectance spectrum curves of different coatings in the wavelength range of 300 nm to 2500 nm were measured. The results show that the solar reflectance of the coating S0 is much lower than that of the other five coatings, and meanwhile, the average values of the ultraviolet region reflectance (300 nm-400 nm), the visible region reflectance (400 nm-780 nm), the near infrared region reflectance (780 nm-2500 nm) and the solar light (300 nm-2500 nm) reflectance of different coatings are calculated, and the results are shown in FIG. 3 (b). The visible and near infrared reflectivities of coating S0 were 44.2% and 40.8%, respectively, while the visible and near infrared reflectivities of coatings S1, S2, S3, S4, and S5 were greater than 80% and 75%, respectively. Further, the solar reflectance of the coatings S0, S1, S2, S3, S4, and S5 were 41.4%, 81.7%, 87.2%, 89.5%, 82.4%, and 78.9%, respectively. According to the energy-saving standard of China buildings (JG/T235-2014), the solar reflectance of the reflective heat-insulating coating for buildings is required to be greater than or equal to 65%, and the near-infrared reflectance is required to be greater than or equal to 80%. The near infrared and solar reflectivities of coating S3 were highest, 89.2% and 89.5%, respectively, and thus coating S3 was optimized for solar reflectivity over the other coatings.

To investigate the actual heat reflection properties of the coatings under solar radiation, six different coatings were left suspended outdoors as shown in fig. 3(c), and the experiment was performed in suzhou at 16

days

5 and 16/2021, sunny day with a maximum temperature of 35 ℃. The experiment was started at 9:00 am and ended at 17:00 pm, and the average temperature of the surface of each coating was measured and calculated every 1 h with an infrared thermometer. The changes in the average temperature of the coating surface with time are shown in fig. 3(d), and the results show that the average temperature of the surface of coating S0 at 12:00 to 14:00 is 54.68 ℃, 55.22 ℃ and 53.00 ℃ respectively, while the average temperature of the surface of coating S3 at 12:00 to 14:00 is 46.00 ℃, 45.58 ℃ and 45.65 ℃ respectively. The coating S0 is a common cement coating which is not sprayed with an excessively high-reflection wear-resistant super-hydrophobic coating, the sunlight reflectivity is not high, and the surface temperature under the sunlight radiation is very high. In contrast, coating S3 has a high solar reflectance and is capable of reflecting radiant energy in the visible and near infrared regions with a maximum temperature reduction of about 10 ℃. The above results indicate that the high-reflection wear-resistant super-hydrophobic coating has excellent heat reflection effect. Coating S3 was selected for the following experiment.

Tape peel test. The super-hydrophobic coating inevitably contacts with foreign matters in the daily use process, and the surface generates actions such as friction, collision, adhesion and the like. During the contact process, the fragile microstructure and low surface energy material of the surface of the super-hydrophobic coating can be damaged, thereby leading to the loss of super-hydrophobicity of the coating. The tape peel test was performed to examine the adhesion of the coating material to the substrate surface. The experimental scheme is shown in FIG. 4 (a). In the test process, a 3M adhesive tape is tightly attached to the surface of the super-hydrophobic coating, a 1 kg weight is loaded on the adhesive tape and kept for 5 min to ensure that the surface of the coating is completely contacted with the adhesive tape, then the weight is taken down, and the adhesive tape is uncovered. After repeating the above operation five times, the CA and SA of the coating surface were measured, and this process was regarded as one peeling cycle. The result of the coating after 10 cycles of peeling (50 tape peeling) is shown in fig. 4(b), and the water droplets maintain a good spherical state on the coating surface. As can be seen from fig. 4(c), the coating showed a slight decrease in CA and a slight increase in SA throughout the peel test, but remained superhydrophobic overall, showing excellent stability.

And (6) wear testing. Currently, abrasion resistance of a superhydrophobic coating is evaluated by abrading the surface of the superhydrophobic coating with sandpaper is one of the most common methods. Fig. 5(a) is an experimental diagram illustrating the abrasion of a coating layer by sandpaper. An 800 mesh sandpaper was placed horizontally on a table, and then the surface containing the superhydrophobic coating was attached to the sandpaper and the sample was pushed in a straight line under a load of 500 g weight. The sample was moved at a speed of 5 cm/s and a distance of 20 cm, and then CA and SA were measured on the surface of the coating layer, and this process was regarded as one abrasion cycle. The results of the coating after 10 abrasion cycles are shown in fig. 5(b), and it can be seen that the coating does not lose superhydrophobicity. After 10 wear cycles, the surface CA of the coating was still above 150 ° and SA was still below 10 ° (fig. 5 (c)), indicating that the coating still maintains excellent superhydrophobicity. The abrasion test was performed using sandpaper of 400 and 1200 mesh, and the result was substantially the same as that of fig. 5 (c).

In fig. 6, (a) - (c) are SEM images before the coating is rubbed, and from the images, it can be seen that the micro-nano roughness structure of the coating surface is clearly seen, while in fig. 6, (d) - (f) are SEM images after the coating is rubbed, and it is observed at a low magnification (fig. 6 (d)) that a large number of scratches appear on the coating surface, which is a trace left by rubbing the coating surface with sandpaper, and further, it is observed at a high magnification (fig. 6, (e) - (f)) that the coating surface is still rough, and the micro-nano structure thereof is not damaged. The microscopic appearance of the coating before and after friction is not obviously changed, because the cement substrate is relatively coarse, the coating can be well attached to the substrate, and the cement substrate is very hard after being cured, so that the coating can be effectively protected, and the coating is prevented from being completely rubbed off by sand paper. The above results show that the prepared super-hydrophobic coating has excellent mechanical stability.

Chemical stability and UV resistance. When the super-hydrophobic coating is used in an outdoor environment, the super-hydrophobic coating is corroded by corrosive liquids such as acid rain, alkaline solution and organic solvent, so that the surface hydrophobicity is poor. Therefore, the chemical stability of the prepared high-reflection wear-resistant super-hydrophobic coating is determined. As shown in FIG. 7(a), HCL and NaOH solutions are selected to prepare corrosive solutions with pH values of 2-12, the corrosive solutions are dripped on the coating surface, then the coating surface is kept still for 12 hours, and CA on the coating surface is measured. FIG. 7(b) is a CA on the surface of the coating at different pH values. From the pH test results, it can be seen that the coating has excellent corrosion resistance, and the CA of the surface of the coating is greater than 150 °. When the coating is slightly inclined, spherical liquid drops are easy to roll off from the surface, and no corrosion mark is found on the surface of the coating, which indicates that the prepared high-reflection wear-resistant super-hydrophobic coating has good chemical stability.

The UV resistance of the superhydrophobic coating is also a very important indicator. FIG. 7(c) is a schematic diagram of the UV resistance test of the coating. And (3) irradiating the prepared super-hydrophobic coating under ultraviolet light with the power of 8w, wherein each irradiation time of the coating is 12 h and is an irradiation period, and testing CA and SA of the coating after each irradiation period. Fig. 7(d) shows the effect of the uv irradiation period on the wettability of the coating. As can be seen, the wettability of the coating layer did not change significantly after 14 UV irradiation cycles (168 h). The CA of the coating is more than 150 degrees, and the SA of the coating is less than 10 degrees, and the result shows that the prepared coating has excellent ultraviolet resistance.

And (6) self-cleaning testing. The white sunlight reflecting coating is easily contaminated by pollutants such as dust, liquid and the like, and the sunlight reflectivity is sharply reduced due to the pollutants covering the surface of the coating. Therefore, a superhydrophobic coating with self-cleaning capability may prevent the accumulation of contaminants on the surface. The mixture of soil, lime and gravel is sprayed on the surface of the high-reflection wear-resistant super-hydrophobic coating to simulate pollutants in real life, and the self-cleaning capability of the coating is tested by simulating natural rainfall through continuous water drop impact. As shown in fig. 8(a), after a small amount of tap water was continuously dropped, it was observed that the contaminants on the surface of the coating were completely carried away by the water droplets, indicating that the coating had good self-cleaning properties under natural rainfall conditions. As shown in FIG. 8(b), the tomato paste was dropped on the coating and then slowly lifted, and the tomato paste was seen to roll down without staining the coating surface, indicating that the super-hydrophobic coating also has a certain self-cleaning ability to viscous liquid. In addition, various liquids, especially liquid foods, which are frequently used in daily life, are easily splashed onto the surface of the solar light reflective coating, thereby deteriorating the reflectivity of the surface of the coating. Figure 8(c) shows that various liquids (blue ink, honey, mud, saline, coffee, cola) take on a spherical shape on the surface of the coating. When these liquids are dropped on the surface of the coating, they roll off the surface quickly without any residue after being tilted at an angle. Experiments show that the surface of the high-reflection wear-resistant super-hydrophobic coating is difficult to be attached by pollutants such as dust, liquid and the like, and the excellent self-cleaning performance is shown.

Frost resistance. The water drops on the surface of the super-hydrophobic coating are generally spherical, the contact area between the water drops and the surface is small, and in addition, a large number of gaps exist in the rough structure of the surface of the super-hydrophobic coating, and a part of air can be trapped. The super-hydrophobic coating can effectively prolong the icing time of the water drops because the air existing between the water drops and the surface of the coating hinders the heat transfer between the water drops and the surface of the coating. In order to explore the frost resistance of the coating, a high-reflection wear-resistant super-hydrophobic coating and a common cement coating are subjected to a frost resistance test. As can be seen from fig. 9(a), the water droplets are completely frozen in the portland cement coating layer after 60 seconds, and the water droplets completely lose the spherical shape and are firmly frozen on the surface of the cement coating layer and are difficult to remove. Under the same conditions, water drops on the surface of the high-reflection wear-resistant super-hydrophobic coating need to be completely frozen after 360 seconds (fig. 9 (b)), and the water drops on the surface of the super-hydrophobic coating still keep a spherical shape and fall off by lightly touching. The result shows that the super-hydrophobic coating can not only prolong the icing time, but also effectively reduce the adhesive force between ice and the coating surface.

The super-hydrophobic surface can delay the icing time of water drops, but can not prevent the water drops from icing, so that the phenomenon of icing and snow accumulation easily occurs in a cold environment in winter, and even the super-hydrophobic surface can be subjected to the process of icing, melting and icing again for a long time and the situation that ice blocks are too large and fall off spontaneously, so that the micro-nano structure on the surface of the super-hydrophobic coating can be damaged irreparably. In order to investigate the durability of the high-reflection wear-resistant super-hydrophobic coating in a low-temperature environment, an ice bead peeling cycle test was performed on the surface of the coating, as shown in fig. 9(c), after 40 cycles of repeated icing-deicing processes, the hydrophobic property of the surface of the coating is not greatly affected, CA is basically maintained at 155 °, and SA is increased to a certain extent but is less than 10 °. The test result shows that the high-reflection wear-resistant super-hydrophobic coating has better frost resistance under severe cold conditions, shows good durability and can be widely applied to extremely severe environments.

The invention takes ground limestone (GCC) as a main raw material and titanium dioxide (TiO)₂) For the solar reflection enhancing filler, hydrophilic GCC microparticles and TiO are treated with room temperature vulcanized silicone Rubber (RTV) and tetraethyl orthosilicate (TEOS)₂The nano particles are subjected to surface modification, and the high-reflection wear-resistant super-hydrophobic coating is prepared on the surface of the cement substrate by a simple and environment-friendly method. Different GCC and TiO are explored₂The influence of the mass ratio on the wettability and the sunlight reflection characteristic of the coating is tested and analyzed, and meanwhile, the chemical composition, the micro-morphology, the mechanical stability, the chemical stability, the self-cleaning performance, the frost resistance and the like of the coating are tested and analyzed. By analysing TiO₂GCC and modified GCC/TiO₂FT-IR, XPS of the coating found hydrophilic TiO₂GCC is successfully modified by RTV; GCC and TiO in the prepared high-reflection wear-resistant super-hydrophobic coating₂When the mass ratio is 3: 1, the hydrophobic effect is best, and at the moment, CA and SA are respectively 158 degrees and 5.6 degrees; the prepared high-reflection wear-resistant super-hydrophobic coating has excellent durability, and can still maintain a super-hydrophobic state after 12 hours of corrosion of an acid-base solution; after continuous irradiation for 168 hours under ultraviolet rays, the super-hydrophobicity is not basically changed. According to the energy-saving standard of China buildings (JG/T235-2014), the reflectivity of the reflective heat-insulating coating of the buildings in the near infrared region is required to be greater than or equal to 0.80, and the reflectivity of sunlight is required to be greater than or equal to 65%. The near infrared region and the sunlight reflectivity of the high-reflection wear-resistant super-hydrophobic coating prepared by the invention can respectively reach 89.5 percent and 89.2 percent, and the excellent solar reflectivity is shown Sunlight reflecting property. Meanwhile, outdoor heat reflection performance test is carried out on the coating, and the result shows that the high-reflection wear-resistant super-hydrophobic coating can effectively reduce the surface temperature by about 10 ℃ compared with the common cement coating. The high-reflection abrasion-resistant super-hydrophobic coating also has excellent abrasion resistance, can be used for carrying a 500 g weight, and still can keep CA above 150 degrees and SA below 10 degrees after being rubbed on the surface of 800-mesh sandpaper for 200 cm or stripped by a tape for 50 times. This benefits from the rough, strong cementitious substrate providing protection to it, enhancing the adhesion between the coating and the substrate, and thus ensuring the mechanical stability of the superhydrophobic coating. The high-reflection wear-resistant super-hydrophobic coating is prepared by a spraying method, has a simple process and can be produced in a large scale. The coating has excellent self-cleaning capability, can remove pollutants such as dust on the surface, has a rejection effect on common liquids in life such as ink, cola and coffee, also shows frost resistance in a low-temperature environment, and can effectively prolong the freezing time of water drops.

Claims

1. A high-reflectivity antiwear super-hydrophobic coating is prepared from modified GCC/TiO₂Drying the suspension to obtain the modified GCC/TiO ₂The suspension comprises ground calcium carbonate, titanium dioxide, room temperature vulcanized rubber and tetraethyl orthosilicate.

2. The highly reflective, wear-resistant and super-hydrophobic coating according to claim 1, wherein the modified GCC/TiO is obtained by mixing titanium dioxide powder, heavy calcium carbonate powder, room temperature vulcanized rubber, tetraethyl orthosilicate, ammonia water and water₂And (3) suspension.

3. The high-reflection wear-resistant super-hydrophobic coating according to claim 2, wherein the mass ratio of the heavy calcium carbonate to the titanium dioxide is (1-10) to 1.

4. The high-reflection wear-resistant super-hydrophobic coating according to claim 2, wherein the mass ratio of the heavy calcium carbonate to the titanium dioxide, the tetraethyl orthosilicate, the room-temperature vulcanized rubber and the ammonia water is 8g to (1-3) mL to (0.2-0.8) mL.

5. The method for preparing the highly reflective, wear-resistant and superhydrophobic coating of claim 1, wherein the modified GCC/TiO is obtained by adding titanium dioxide powder to water, adding ground limestone powder, adding tetraethyl orthosilicate, room temperature vulcanized rubber and ammonia water₂A suspension; drying the modified GCC/TiO₂The suspension liquid obtains a high-reflection wear-resistant super-hydrophobic coating.

6. The high-reflection wear-resistant super-hydrophobic material consists of a substrate and a coating on the substrate, and is characterized in that the coating is made of modified GCC/TiO₂Drying the suspension to obtain the suspension; the modified GCC/TiO₂The suspension comprises ground calcium carbonate, titanium dioxide, room temperature vulcanized rubber and tetraethyl orthosilicate.

7. The high-reflection wear-resistant super-hydrophobic material as claimed in claim 6, wherein the mass ratio of the ground limestone to the titanium dioxide is (1-10) to 1.

8. The highly reflective, abrasion-resistant and superhydrophobic material of claim 6, wherein the substrate is an inorganic material or an organic material.

9. The preparation method of the high-reflection wear-resistant super-hydrophobic material as claimed in claim 6, wherein the modified GCC/TiO is added₂And spraying the suspension on a substrate, and drying to obtain the high-reflection wear-resistant super-hydrophobic material.

10. Use of the highly reflective, abrasion-resistant and superhydrophobic coating of claim 1 in the preparation of a highly reflective, abrasion-resistant and superhydrophobic material.