Titanium Dioxide
What is Titanium Dioxide?
Titanium dioxide (TiO₂) is a fine white powder or dust that occurs naturally. It was first intentionally produced for use as a white pigment in 1923.
It is naturally opaque and bright, which makes it useful for use in paper, ceramics, rubber, textiles, paints, inks, plastics and cosmetics. It is also resistant to ultraviolet (UV) light, and is used widely in sunscreens and pigments that are likely to be exposed to UV light. It is used in a wide variety of personal care products, including color cosmetics such as eye shadow and blush, loose and pressed powders and in sunscreens.
Titanium Dioxide for Plastics
TiO₂ is a multifaceted material when used in polymer applications. It has been long established as the leading white pigment, and this is the application that people are most familiar with. However, titanium dioxide brings more to the polymer industry than just white, bright opacity. In a more basic sense, titanium dioxide is a photo-responsive material—its value is in its interaction with light. For example, this interaction can be the familiar scattering that results in opacity or it could be the absorption of UV light energy, thereby protecting the polymer from UV degradation. Applications continue to develop, all based on the interaction of the titanium dioxide particle with light.
As other applications for titanium dioxide have developed, its pigmentary properties remain the most important. Titanium dioxide is the most important white pigment used in the polymer industry. It is widely used, because it efficiently scatters visible light, thereby imparting whiteness, brightness, and opacity when incorporated into a plastic product. It is chemically inert, insoluble in polymers, and heat stable under the harshest of processing conditions. Titanium dioxide is commercially available in two crystal forms—anatase and rutile. The rutile pigments are preferred over anatase pigments, because they scatter light more efficiently, are more stable, and are less likely to catalyze photodegradation.
Few, if any, commercial grades of titanium dioxide are pure TiO₂. Most have inorganic and, in some cases, organic treatments deposited on the surfaces of the TiO₂ particles by precipitation, mechanical blending, or via other routes. These surface treatments provide improvements in one or more performance properties of the pigment, such as ease of dispersion, weatherability, or discoloration resistance. A single prescription for surface treatment does not produce a pigment having maximum value-in-use for all plastics applications, and it is a continuing research goal to develop titanium dioxide grades to meet the changing needs of the plastics industry.