More than ever, titanium dioxide is on everyone’s lips in the paints, coatings and printing inks industry. Image: Syda Productions-Fotolia
26. Feb 2018 | Raw materials
Event report: Making more of titanium dioxide
There is a lack of substitutes for titanium dioxide yet but there are ways to improve its efficiency – this was tenor of the EC Titanium Dioxide Forum. Videos from the event and proceeding are now available in European Coatings 360°. What was discussed at the conference?
More than ever, titanium dioxide is on everyone’s lips in the paints, coatings and printing inks industry. From a possible classification looming at the horizon to supply shortages to ever-increasing prices, the challenges are galore. More than 90 experts gathered at the beginning of January at the European Coatings Titanium Dioxide Forum in Berlin to discuss products and strategies to maximise the efficiency of TiO2.
Before the technical presentations, Reg Adams of Artikol gave an overview of the current situation on the market for titanium dioxide. He noted prices for TiO2 are oscillating and underlined that not only paints, coatings and inks manufacturers have high demands of titanium dioxide but also the plastics sector, the paper industry as well as many other end use applications.
No substitution to date
Running like a golden thread throughout the presentations and the discussions was the view that titanium dioxide is not replaceable. Dr Jitte Flapper of Akzo Nobel, for instance, presented the results of his theoretical study into the hiding power of white TiO2-free coatings. The best results were gained with zinc sulfide, but which still required a two times thicker layer and is likely to cause problems with regards to legislatory issues. Zirconium dioxide is less problematic in that respect but also needs a layer four times as thick. The results for air showed that an eight times thicker layer was necessary. From the unsuccessful results Flapper concluded that none of the tested substances can to date be considered as a proper replacement for TiO2.
Present in many of the speeches was also the notion that there are restrictions in the reduction of titanium dioxide. This was for example underlined by Dennis Werner of Omya who gave insights into the role of fillers in TiO2 reduction. While showing that the usage of the pigment can be optimised using functional minerals he also emphasised that there are both technical and commercial limits to the reduction of titanium dioxide.
From all fields of coatings technology
Another factor that can contribute to improve the efficiency of titanium dioxide is of course better milling. Dr Hans Joachim Jacob of Ystral presented a new technology for the dispersion of titanium dioxide that is based on an inline technology.
Dr Janet Preston of Imerys looked at titanium dioxide usage in white flexo inks which often contain level of TiO2 that exceed 30 % pigment volume concentration. She tested the usage of ground calcium carbonate, precipitated calcium carbonate, kaolin and talc as extenders. The best results were obtained for ultrafine kaolin and precipitated calcium carbonate.
Spacing and collodial interactions
A recurring topic was also better spacing between the titanium dioxide pigments. Dr Anne Koller of The Dow Chemical Company stressed in her presentation that TiO2 is not used efficiently in paints. She presented a binder that is able to associate Ti02 pigments to space them in the wet and dry states to improving the efficiency of hiding.
Dr Uwe Wilkenhöhner of titanium manufacturer Kronos, emphasised that particle spacing is critical. He presented self-spacing titanium dioxide which is currently being developed. Wilkenhöhner also spoke about the usage of titanium dioxide slurries which can offer benefits such as a dust-free working environment. While slurries are widely used the U.S., they are less popular in Europe.
Another strategy to be able to optimise of titanium dioxide is to analyse the collodial interactions. Dr Immanuel Willerich of BASF spoke about how improving these interactions allows the producer to control the nanoscale structure formation between the different components in the paint. He stated that interaction-optimised raw materials and formulations could deliver better hiding performance.
Looking outside the box
A different approach was presented by Dr Hendrik Hölscher of the Institute of Microstructure Technology of the Karlsruhe Institute of Technology. In his speech he introduced materials inspired by nature, most notably the White Beetle which scales produce a nearly perfect whiteness that inspired a highly scattering white polymer film.
Proceedings and videos available
Titanium Dioxide (2nd Revised Edition) Production, Properties and Effective Usage This second, completely revised edition contains a wealth of information on the properties and use of titanium dioxide pigments. It gives the reader a comprehensive insight into how titanium dioxide works and its possible applications, as well as discussing the current state of development and its use in various forms for UV absorbers, effect pigments and catalytic materials. Practitioners will especially welcome the fact that Chapter 4 now includes information on the scope for, and limitations on, replacing titanium dioxide pigments in formulations.
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