In the ongoing shift from solvent- to water-based coatings, alkyds have stubbornly resisted the change, and for valid reasons. Solvent-based alkyds are cost efficient and versatile, with a long history of proven performance in architectural, industrial and specialty applications. They offer excellent adhesion, hardness, gloss and corrosion resistance. These resins are also highly viscous: they originate as solids, making it very difficult to formulate shelf-stable coatings without the addition of solvent. Despite numerous options, including water-reducible alkyds, modified alkyd dispersions and alkyd emulsions, only 10% of alkyd-based coatings are currently waterborne.1 Challenges to widespread adoption include delayed hardness development, lower gloss and reduced corrosion protection. To help formulators bridge the performance gap and produce differentiated products in this space, Dow Coating Materials has developed a novel dispersion technology that can be used to formulate waterborne alkyds that can perform as well as or better than solventborne versions.
With an estimated annual value of $25 billion USD, alkyds are among the most widely used binder chemistries for paints and coatings.2 In architectural applications, they are a go-to option where low cost and high gloss are desired. On metal substrates, they offer excellent adhesion, corrosion resistance and gloss. Although solventborne options dominate in this binder category, accounting for approximately 60%, or 3 billion pounds, of annual consumption,3 a Voice of the Market Study suggests that most formulators would prefer waterborne options.4 Compared to their solventborne counterparts, waterborne coatings offer lower VOC capability, improved personal safety, soap-and-water clean-up and easier disposal. So what’s holding waterborne back? Current options fall into one of three categories.