Transparent iron oxide pigments produce a depth of shade that is perceived as rich and prestigious among consumers. Due to their coloristic performance, UV resistance and high transparency nature, these pigments found strong applications in wood and automotive coatings.
One of the big challenges paint formulators face when working with transparent iron oxide pigments is their poor surface wetting properties in aqueous systems, leading to long grind times, high viscosity and lower than desired transparency. As a result, these pigments found limited usage in the rapidly growing waterborne wood and automotive coatings. This paper will discuss why these pigments are so appealing yet difficult to disperse and how to overcome these challenges using unique pigment wetting technology based on polyurethane chemistry engineered with a combination of different anchoring groups specifically designed and positioned to provide fast and strong interactions with the surface of these pigments.
Four leading grades of red and yellow transparent iron oxide pigments are evaluated using several stabilizing technologies to demonstrate the correlation between the particle size distribution of the grinds and its impact on transparency, viscosity and stability of the dispersion.
Additionally, a method for quantifying transparency is demonstrated using 1k and 2k acrylic binder systems where dE* between absolute black and coated black is measured using two spectrometric techniques.
Producing and applying high performance waterborne transparent iron oxide pigment dispersions is now possible and easier than ever before.