Titanium Dioxide Goes Beyond White Pigment to Complex Inorganic Coloured Pigments

Titanium Dioxide (TiO₂) is best known as a white pigment used in paints, plastics and paper, where it is the pigment of choice to give opacity and whiteness to a large variety of everyday materials. What is lesser known is that TiO₂ can also be used as an ingredient to manufacture coloured pigments and more specifically complex inorganic coloured pigments (CICPs) also called Mixed Metal Oxide (MMO) pigments.

CICPs are known for their increased durability, inertness and good chemical stability. These properties are important as they are often used in harsh conditions where the resistance to fading, because of the mentioned features, is a valued feature of CICPs. Due to their chemical stability and durability, CICPs will retain their vibrant colours better under attack from polluting chemicals.

MMO pigments get their name from the production process, where various metal oxides, different combinations and/or different ratios are blended and heated to very high temperatures. At these temperatures, the metal oxide ions rearrange themselves to form a structure, e.g. rutile or spinel with increased stability.

Historically these inorganic coloured pigments were used in decorative ceramics and pottery. Nowadays, the field of application is much broader as they are used in coatings, which need their increased resistance to weathering, such as coil, powder and exterior industrial coatings, but are also used in concrete, roof granules and even some types of plastics.

These various combinations of different oxides as well as the ratio of the different metals, lead to a spectrum of colours from bright yellows over oranges to dark browns. Titanium dioxide mixed with oxides from Nickel and Antimony will result in yellow colours whereas the combination of Titanium, Antimony and Chromium oxides will give you the well-known buff-yellow colour, which is often associated with coloured pigments based on TiO₂. Titanium, Zinc and Tin oxides will give a range from bright yellow to orange and a blend of Titanium, Antimony and Manganese will result in darker brown colours.

Most of the above-mentioned colours will have a rutile structure. Combinations with Iron, which mostly forms the spinel structure, will be brown, ranging from light to dark shades of the colour.

Tronox anatase TiO₂ pigments, such as TiONA^® AT-1 are being widely used in this application. A higher purity grade, TiONA^® ATP-01 was introduced recently and has been well accepted by the coloured pigments industry major players.

Beyond its reputation for being the brightest, whitest pigment available, titanium dioxide helps to create a world of colour.