Influence of titanium dioxide pigments in paints and coatings with regard to the 2010 VOC Regulation

Jürgen Bender and Thomas von Oppenkowski, Kronos International, Inc., Germany

The importance of environmental aspects in the paints and coatings industry has been growing for many years. One focus in this context is reduction of the level of solvents (volatile organic compounds - VOCs) in paints and coatings. From 2010 onwards, producers and users will again face new challenges, since there will be significant changes in paint formulation, partly due to new binder systems with reduced solvent contents. As a result of this, traditional paints and coatings will disappear from the market. For processors, this development will additionally be accompanied by different properties resulting from the changed formulations.

Most binder manufacturers offer VOC-compliant products with changed properties. KRONOS INTERNATIONAL, Inc. subjected the influence of TiO2 pigments to exhaustive investigation in a study of application properties. In this context, the performance properties of titanium dioxide pigments were examined both in modern high-solids systems and in various waterborne paint systems.

This laboratory work focused not only on the optical properties, such as brightness, tone, gloss and hiding power, but also on the dispersibility and weather resistance of differently post-treated TiO2 pigments manufactured by the chloride and sulphate processes. The paints and coatings formulated with different TiO2 pigments were assessed in relation to their drying behaviour, sagging and levelling. It is additionally reported whether higher loading with special titanium dioxide pigments is possible in high-solids systems, as already determined in previous studies. We furthermore examined the question of whether and to what extent titanium dioxide pigments can contribute to reducing VOCs in paint systems. Finally, pigment recommendations are given that relate, among other things, to the individual requirements profile of the paints and coatings, the dispersing equipment used by the producer and the processing properties.