Preparation of nanosized anatase TiO2-coated kaolin composites and their pigmentary properties

Nanosized anatase TiO2-coated kaolin composites were prepared by the chemical deposition method starting from calcined kaolin and TiCl4. The resultant TiO2 nanoparticles on the kaolin surfaces existed in anatase phase after calcination at 200, 400, and 900 °C for 1 h, respectively. The surfaces of the kaolin powders were uniformly coated by a monolayer of TiO2 nanoparticles. The higher calcination temperature was beneficial to formation of well crystallized anatase TiO2 nanoparticles. The light scattering indexes of the TiO2-coated calcined kaolin composites were two times higher than that of the kaolin substrate. XPS analysis shows that TiO2 coating layers anchored at the kaolin surfaces via the Ti–O–Si and Ti–O–Al bonds.