Preparation And Properties Of Hydrophobically Modified SiO₂ Based Composite Self-cleaning Coatings

In recent years,more and more attention has been paid to the preparation and application of self-cleaning protective coatings.Water consumption for indoor and outdoor glass,ceramic sheets,metals and other surface cleaning continues to increase.Under the background of water-saving society advocated by the state,reducing water consumption for cleaning has become one of the important measures in the field of water saving.Coating can also prevent accidents caused by metal moisture corrosion and reduce the use of detergents to reduce the environmental impact of surfactants.On the other hand,indoor toilet consumes a large amount of domestic water due to flushing,so the use of super-slippery layer can effectively reduce the use of toilet flushing water and toilet cleaner,and reduce the harm to the environment while saving water.In this study,based on the hydrophobic modified silica,three kinds of coatings were prepared for different application scenarios: FEVE fluorocarbon resin hydrophobic coating,RTV composite superhydrophobic coating and ultra-slippery coating.Two kinds of silane coupling agents,HDTMS and KH-570,were used to modify silica hydrophobically,and the modification was proved to be successful by infrared spectrum analysis and thermogravimetric analysis.In the process of coating preparation,FEVE fluorocarbon resin hydrophobic coating was prepared by sol-gel method.The static contact Angle of the surface to water reached 147°,and more than 72% of clean water could be saved after application.The curing time was only 20 minutes.After cutting and friction,it still has hydrophobic effect,and the contact Angle to water is more than145°.It has the advantages of short curing time,excellent surface morphology and good durability.RTV composite superhydrophobic coating was prepared by natural sedimentation method.The static contact Angle to water was 154.2°,and the rolling contact Angle was 5-8°,which achieved the superhydrophobic effect.After application,82.1% of clean water could be saved.For indoor application scenario for the toilet,this study combined with viscoelastic solid adhesion factors such as the preparation of the ultra smooth coating,to make waste such as viscoelastic solid drip immediately fell after coating on the surface,to reduce flushing water,under the premise that achieve health standard cut clean water use,to get more accurate data,the experimental process were simulated stool samples,A series of self-cleaning properties of the superslippery coating were studied by using the simulated feces samples,including the adhesion of viscoelastic solids on the surface of the coating.The simulated feces samples could slide off autonomously within 1.35 s without leaving any trace after dripping on the surface of the coating.Analysis of the influence of ambient temperature on coating properties shows that-25 ℃-50℃ has no obvious influence on the sliding time of viscoelastic solid.The use of cleaning water can be reduced by using super smooth coating,at the same time can reduce household toilet cleaners in the use of more than 50%,the public can reduce 83.3% of the use of cleaner such as toilet,at the same time to analyze the performance of the coating for water flushing capacity,choose different impact velocity of the flow after coating,viscoelastic solid can fall within 1.7 s,It shows that the water scour has little effect on the coating,and the environmental protection of the coating is analyzed.In the experiment,when the ceramic plate was tilted at 30 °,the simulated fecal sample could slide off autonomously 0.65 s after dripping on the coating surface,leaving no trace.According to the theoretical calculation,after 500 times of repeated flushing,the self-sliding time of simulated fecal samples on the surface of the coating is 115±6s,indicating that the super-slip coating still has the effect of repelling viscoelastic solid after 500 times of repeated flushing.