Titanium dioxide pigments (commonly named titanium white) are the most important and the most widespread inorganic pigments. They owe their popularity mainly to their unique lightening power. Apart from exceptional pigmenting virtues, titanium dioxide is an excellent absorber of destructive UV radiation, is chemically passive, insoluble (thus not susceptible to migration), thermally stable and non-toxic.
Titanium dioxide belongs to the most important semi-finished chemical products. It plays a key role in many applications contributing to the increase of utility value of a pigmented product, the most often to giving it a specific aesthetics: non-transparency, colour or gloss.
Additionally, thanks to high the absorption of UV radiation, use of titanium dioxide increases the product durability, and thanks to its non-toxicity it is more environmentally friendly.
Among a white substances, titanium dioxide is characterised by the highest index of refraction, and thus the highest ability of its scattering. This allows making the pigmented products almost ideally white and non-transparent.
Titanium dioxide in the pure form is a colourless, crystalline solid body, non-volatile, non-flammable and non-toxic. It shows high chemical and thermal stability.
Titanium dioxide is polymorphic and occurs naturally in the three crystal forms – as anatase, rutile and brookite, of which only anatase and rutile are of practical significance.
Rutile is the most thermodynamically stable form of TiO2 and definitely the most resistant to the atmospheric conditions; two other forms are less stable. Thanks to higher index of refraction, rutile scatters the visible light more efficiently, and despite the fact that it is characterised by greater hardness and has got slightly yellowish shade, it is more broadly used than the anatase type.
It is required from the titanium dioxide in the pigment applications to be characterised by very high purity, adapted with its crystallographic form to an application, required physical-chemical and optical properties, and often with high resistance to atmospheric conditions.