De-agglomeration and dispersion of nano-TiO2 in an agitator bead mill

The de-agglomeration and dispersion of nano-TiO2 powder is little reported, although nano-TiO2 powder has been widely used due to its unique optical properties. In this study, an agitator bead mill (MiniZETA 03E, Netzsch) accompanied with an ultrasonicator was employed to de-agglomerate the nano-TiO2 powder in butyl acetate, and the effects of ultrasonic pretreatment, dispersant dosage, agitation speed, solid content of TiO2 suspension, and bead diameter were systemically investigated. It is found that ultrasonic pretreatment leads to short grinding time to reach the limiting fineness, low specific energy input, and small limiting mean size. All other technical parameters have also some influence on the limiting fineness and grinding time. However, the former strongly depends on agitation speed while the latter on both agitation speed and dispersant dosage. A solvent-borne nano-TiO2 suspension with limiting mean size of 110 nm can be successfully result under the optimal technical conditions and showed excellent UV-shielding property and transparence when it was incorporated into polyester/melamine coatings.