Materials Science

LANXESS increases production volume of micronized iron oxide red pigments


LANXESS continues to optimize its global production network for the manufacture of iron oxide pigments. Through targeted “debottlenecking” at the Krefeld-Uerdingen site, the specialty chemicals company has increased the product availability of its Bayferrox and Colortherm micronized red pigments by more than 5,000 metric tons per year. “In the paints and coatings industry and also for plastics applications, we see a continuously rising demand for high quality pigments which offer good dispersion characteristics. We have therefore increased product availability for our customers,” says Holger Hüppeler, head of the LANXESS Inorganic Pigments business unit.

Due to their properties, micronized iron oxide pigments from LANXESS are mainly used in technically demanding paints and coating systems and for colouring plastics. The micronization process is characterized by intensive milling in which the proportion of agglomerates is significantly reduced. Micronized pigments can thus be more readily dispersed. In addition, they provide high colour strength and colour consistency.

LANXESS uses its proprietary Laux process to manufacture Bayferrox and Colortherm red pigments at its site in Krefeld-Uerdingen, Germany. Black pigments are heated up to 800 °C and oxidized to red pigment. Since the Copperas process, which was an alternative, is no longer used worldwide on a market-relevant scale, the much more environmentally friendly Laux process is the only production process applied for iron oxide red pigments that includes a calcination step at very high temperatures. This results in particularly stable pigments which, after a subsequent milling process, have unique properties which distinguish them from all other iron oxide pigments available on the market in two essential respects:

Micronized red pigments from the Laux process have the highest milling stability. Even when subjected to high shear forces during the dispersion process, they show excellent resistance to colour change.

These pigment types also lead in terms of temperature stability. They are thermally stable even up to temperatures of 800 °C, while red pigments (hematite, Fe2O3) produced using other manufacturing processes are typically only resistant up to a maximum of 400 °C. Due to the high temperatures applied during calcination in the Laux process, all water inclusions that can promote a colour shift are displaced from the oxide crystal lattice. For this reason, micronized red pigments from LANXESS do not display a colour shift in use, even at extremely high application temperatures.