Preparation Of Modified Superhydrophobic Particles Of Silicon Dioxide And Their Effect On Stain Resistance Of Exterior Wall Emulsion Coating

Compared with the traditional brick,emulsion paint of exterior wall has the advantages of colorful,simple construction,safe and reliable.It has a very good prospect in the field of decorative materials of exterior wall.The main factor that causes the performance degradation of exterior latex paint film is contamination.Finding a simple way to enhance the stain resistance effectively is the key to impact the degree of the actual application of exterior wall paint.Superhydrophobic surface is from the "lotus leaf effect" as inspiration and developed.Micro-nanostructures and low surface energy are conditions in which they have good hydrophobicity.It has a self-cleaning effect similar to the lotus leaf.Thus,we intend to produce superhydrophobic particles using modified silicon dioxide and spray them on the external wall paint film surface to enhance the paint's stain resistance and persistence of superhydrophobic particles at the same time.Particle size of silicon dioxide microspheres is a key factor affecting micro/nanostructures.The experiment was designed according to the response surface method on the basis of single factor experiment and the data were processed by computer.A model for the particle size of silicon dioxide microspheres prepared by sol-gel method was finally established.The influence of interaction was analyzed by using response surface.The synthesis of silicon dioxide microspheres with specific particle size was optimized by the model.Compared to the actual situation,the error value is found in IOOnm or less.The model can provide a good reference for later researchers.Nano-silicon dioxide particles was modified by low-cost industrial hydrogenated silicone oil.The modified nano-silicon dioxide was characterized by FTIR,TG and EDS.It was confirmed that the hydrogen-containing silicone oil was successfully grafted onto the surface of silica microspheres,and the modification was successful.Different reaction parameters(including particle size,amount of hydrogenated silicone oil,modification time)were screened.The superhydrophobic surface with contact angle of up to 168.54° and rolling angle of 3-5° was obtained by spraying particles on the substrate surface.The effects of surface tension on the wettability of superhydrophobic surfaces were studied.The reason for the formation of superhydrophobic is speculated by reaction mechanism.And the correctness of the conjecture was confirmed by scanning electron microscopy(SEM).Selecting the common external emulsion paint—styrene-acrylic latex paint as a representative,the effects of matrix on the stain resistance and drying time of the film were studied by brushing it on four different substrates(tinplate,cement slab,wood,PVC plywood).Latex films with different contact angles was obtained by spraying the superhydrophobic particles at different drying time.The relationship between hydrophobicity and stain resistance was investigated.The effects of drying time on the.depth of superhydrophobic particles entered and the pencil hardness of the film were investigated by observing the microstructure of the interface between superhydrophobic particles and latex paint.Scratch resistance of superhydrophobic coating was evaluatd by pencil hardness.Eventually,we think the film has improved resistance to dirt by superhydrophobic particles.As the drying time increases,the film depth of particles entered becomes lighter,resulting in poor adhesion of particles and scratch resistance of superhydrophobic coating while the hydrophobicity of the film is enhanced.The appropriate choice can get a good overall performance of the film.