Overview of TiO2 Surface Treatment
Surface treatment refers to the coating of one or more layers of inorganic or organic substances on the surface of titanium dioxide pigment particles by means of different surface treatment agents and processes, in order to improve the inherent defects of titanium dioxide or to change the surface properties of its particles and to improve its weatherability, dispersibility and other application properties.
The surface treatment of titanium dioxide is mainly through the isoelectric point theory and stability theory, using precipitation, adsorption, ion exchange, covalent bonding and polymer grafting reaction to modify the surface of titanium dioxide, the result of the modification only involves the change of surface charge, surface area change, in order to compensate for the photochemical activity of titanium dioxide defects, improve the weatherability and durability of titanium dioxide, improve its wettability in various media and dispersibility.
The surface treatment does not change the crystalline structure, particle size, particle size distribution and colour of the titanium dioxide (which is controlled by the oxidation process).
There are lattice defects on the surface of pure TiO2, which makes many photoactivation points on the surface of TiO2 particles, and the photoactivation points are very active under the action of ultraviolet light. The smaller the TiO2 particles, the more photo-activation points, the worse the weather resistance.
Unprocessed titanium dioxide whose calcined particles are very small, has a high specific surface energy, extremely unstable, at high temperatures will quickly agglomerate, forming sub-stable larger particles, for TiO2, the smaller the particles, the stronger the gravitational force between the particles, the particles are more likely to agglomerate
In order to improve the weatherability and chemical stability of TiO2, and to improve the dispersion of TiO2 in various different media, surface treatment is usually applied to TiO2. Surface treatment is to form a uniform film on the surface of TiO2 particles to block the photoactivation point of TiO2 and improve weathering resistance.
