SURFACE TREATMENT METHOD FOR MAKING HIGH DURABILITY UNIVERSAL TITANIUM DIOXIDE RUTILE PIGMENT

摘要

A method is provided for the wet surface treatment of titanium dioxide, in order to produce durable universal grade titanium dioxide rutile pigment with superior optical properties. The method is characterized in that, a hydrous zirconia and silica composite layer is co-precipitated at acidic pH. Then, a layer of alumina is precipitated under a range of pH required for complete precipitation above the initial composite layer. The upper pH limit of the slurry during the alumina precipitation can be well controlled to avoid any chance for dissolution or damage of the composite zirconia-silica layer formed. Zirconia-silica composite layers and alumina thus precipitated advantageously improve the competence of the layers formed over a TiO 2 base and provide improved durability with superior optical performance. The total surface treatment cycle time and chemicals used are minimal compared to conventional methods. Improvements in throughput and washing efficiency are also realized.