By Frédéric Lucas, Jules Mikhael and Ulrich Tromsdorf, BASF SE. Understanding the main phenomena occurring during the formulation, film formation and drying of two-component water-borne polyurethane coatings has been a subject of recent interest and a challenging task. Indeed, studying these multi-component systems which can undergo a wide range of reactions defies straightforward analysis. A study was therefore made to find methods which are suitable for establishing what occurs when the two components (polyisocyanate hardener and OH-functional dispersion) of water-borne polyurethane coatings are formulated. Density Gradient Ultra-centrifugation (DGU) ...