High efficiency acrylic polyol dispersions for 2K WB PU systems

 
The film formation dynamics and kinetics of the WB 2K PU coating systems are significantly challenging due to heterogeneity of the binder and polyisocyanates (PIC), dispersed in the water. To achieve higher performance in industrial applications, often conventional solvent-based PICs are preferred crosslinkers in WB systems too. This poses challenges to optimize optical and mechanical properties of such coatings. Due to competing reactions of PIC with water and the polyol, WB 2K PU systems are commonly designed with higher stoichiometric excess of PIC. This brings additional cost-in-use for such systems especially with high OH number binders. On the other aspect, most of the secondary WB dispersions designed for glossy application contains some organic solvents, leaving less flexibility in choice of solvents in coating formulation. In this work we investigated strategic design of OH functional WB dispersions with solvent-free synthesis at relatively lower OH number. The strategic design enabled the dispersion to maximize the crosslinking potential of it to achieve comparable optical and mechanical properties to that of solvent containing high OH number conventional dispersions.