• Parasida, Claire F.
• Kynde, Soren
• Midtgaard, Soren R.
• Arleth, Lise
• Jensen, Grethe Vestergaard
• Zalich, Michael
• Ducher, Pascal
• Lof, David
• Hamieau, Guillaume

Abstract

<p>The dispersion state of titania (TiO2) pigment particles in coatings is crucial to obtain optimal optical properties while minimizing the consumption of pigment, and thereby the cost and environmental impact of the product. By having the particles well-dispersed, with limited aggregation, the best opacity can be obtained with the smallest amount of pigment. The aggregation of titania particles is typically investigated using various microscopy techniques on the dry coating. In this work, Small-Angle X-ray Scattering was applied as a non-invasive tool to probe the distribution of titania during the coating drying process. The titania pigment particles were dispersed by using either a polymeric surfactant or nanosized silica particles as dispersant. The use of silica nanoparticles resulted in the highest degree of dispersion, both in dilute suspension, and in acrylic and alkyd-based coating formulations. Only minor changes in the aggregate structure was observed during drying of the coatings, indicating that the optical performance is to a large extent determined already before drying, in the wet paint. For the formulations containing nanosilica dispersant, the drying time was increased by diluting the paint or by adding less dryer catalyst. The former resulted in a reduced pigment dispersion, whereas the latter seems to increase the degree of dispersion. In both cases, however, the change of dispersion during the drying phase remained minor.</p>

Topics

• nanoparticle
• impedance spectroscopy
• dispersion
• phase
• laser emission spectroscopy
• drying
• surfactant
• X-ray scattering
• microscopy