| Because of special characters, nano-technology has been a field of growing interest in recent years. Nano-composite coatings exhibiting many functions and high performance ,which can be manufactured by adding appropriate nano-particles into polymer and this can be applied to many fields. Regarding its high anti-virus and anti-UV properties, the study of nano-TiO2 becames a focus of the field of coating materials. In this paper, dispersion of nano-TiO2 in water was investigated, and nano-TiO2 modified coatings were prepared, their performance were examinated.Such factors as category and content of dispersant, pH, disperse manner and disperse time, have important effect on the stability of nano-TiO2 aqueous dispersion. The stability of dispersion has been studied by the means of centrifugal machine, spectrophotometer and laser particle-sizer. It is proved that when condition is that dispersant BAS = 1.5%, pH = 10, particle content = 5%(wt%), mixing at high speed for about two hours and with ultrasonic, a stable nano-TiO2 aqueous dispersion can be acquired. The averaged size of nano-TiO2 is under 170nm. In order to get the optimum composition of the nano-TiO2 modified emulsion paint, the influence of main factors on the properties of the modified paint was investigated with orthogonal experiment design method and the best proportion among main materials was obtained. The analysis investigated that the percentage composition of nano-TiO2 has a significant influence on the mechanical properties of coatings. Experimental datum show that the nano-TiO2 modified coatings go up four grade in pencil hardness and its scrub time go from 4200 to 25000, contrasting to the original paint. The properties of nano-TiO2 modified coatings are also much better than original paint.
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