Novel Zero-VOC Deaerators for Waterborne Coatings

By C.J. Reader, C. Hegedus, K.T.G. Lai, C. Louis, S. el Ajaji, W. Chaigneau

Microfoam is a major problem for formulators of low-VOC waterborne coatings. The presence of tiny, trapped air bubbles in a coating film leads to haze and lower gloss, and can also affect coating rheology during application. The method of application, such as roller, brush, or airless or air-assisted spray, has a significant influence on the severity and persistence of the foam developed.

To eliminate such problems, deaerators or defoamers are required as part of the formulation.Deaerators can be either compatible (such as molecular defoamers) or incompatible (oil- or siloxane-based) in composition. This article explores how these compositional and structural parameters can be controlled to “dial-in” deaerator effectiveness and compatibility.

The article also introduces new, zero-VOC deaerators designed to eliminate both macrofoam and microfoam without generating surface defects, so formulators can improve the coating performance on different substrates.