Near-Zero VOC Waterborne Alkyd Dispersions with Solventborne Alkyd Performance

By Erin Vogel, Marty Beebe, Bob Bills, Christina Ellison, Sue Machelski, Jamie Sullivan, Jay Romick, Vennesa Williams

Solventborne alkyds continue to remain popular due to their low cost, ease of application, and great versatility. Nevertheless, alkyd coating volume has been forecasted to decline by two percent per year mainly due to the loss of share to coating technologies that can offer higher performance at lower VOC.² Paints based on waterborne acrylic emulsions have replaced certain SB alkyd coatings due to lower solvent content and faster dry.

However, some coatings from acrylic emulsions can show worse adhesion, gloss, and corrosion resistance compared to SB alkyd coatings at thin film builds (Figure 1). Alkyds, which are typically applied at lower molecular weight than latex paints, display exceptional wetting of the substrate; consequently, their coating films offer higher gloss and corrosion resistance than those from latex paint. In addition, during air drying, alkyds crosslink via oxidation leading to very high molecular weight net-works that further improves their resistance properties (Scheme 1).

Another benefit of alkyds is their hydrophobicity, which contributes to excellent early water and humidity resistance.