The effect of TiO2 pigment on the performance of paratoluene sulphonic acid catalysed paint systems

The work has highlighted the importance of choosing the correct pigment for paratoluene sulphonic acid (PTSA) catalysed paints. Generally, surface treated TiO₂ grades which are basic in nature resulted in the best optical performance in comparison to acidic surface treated grades. The relative performance of the acidic surface treated grade can be improved by increasing the PTSA level in the paint or by using a resin with a higher acidity level. It is postulated that for these TiO₂ grades, the higher acid levels were found to give better steric repulsion. However, overall, the basic surface treated grade retained the best optical performance in PTSA catalysed paint systems.