Vinyl-acetate/ethylene (VAE) emulsions are cost-effective and high-performance binders widely used in low-sheen contractor paints. The hydro-plasticizing effect of water enables VAE co-polymers to exhibit significantly lower minimum film-forming temperature (MFFT) compared to acrylics and vinyl acrylics with similar glass-transition temperatures (Tg).1 As a result, VAE-based paints have lower coalescent demand compared to other binder chemistries. This unique property has enabled paint manufacturers to make high-performance, low-VOC, low-odor paints with VAE emulsions.
However, at higher sheens (semi-gloss), the relative softness of VAE is very detrimental to the development of block resistance. Block resistance is a measure of the surface tack of the painted surface and its tendency to stick to each other when contacted. At higher sheens, VAE-based paints tend to stick to each other, resulting in tearing or peeling upon separation.2 Since higher sheen paints are often used to paint window and door trims, high block resistance is critical to maintain film integrity when opening windows and doors. Also, the higher surface tack makes VAE-based higher sheen paints prone to dirt pickup. Typically trim paints are expected to have room temperature block resistance rating above 5, indicating that the paint film has slight surface tack, but does not stick to each other.