Usually, low-VOC waterborne paints generate dry paint films with lower hardness and dirt pick-up resistance due to the usage of high-boiling-point coalescents. In this work, the effect of low-VOC coalescents on latex film formation, hardness evolution, accelerated dirt pick-up resistance, and surfactant leaching of waterborne paints is explored.
AFM (atomic force microscopy) images of styrene-acrylic and pure acrylic latexes containing 4 wt% of different coalescents show that low-VOC coalescents generated films that were more coalesced and smoother than standard high-VOC coalescent. A new low-VOC coalescent generated semi-gloss paints with higher hardness evolution and better dirt pick-up resistance than commercial low-VOC coalescents and similar to standard high-VOC coalescent.
Moreover, flat paints formulated with this low-VOC coalescent dried at harsh conditions presented lower surfactant leaching in comparison to the ones formulated with standard high-VOC coalescent. These results suggest that there is a correlation between surfactant leaching and film formation assessed through AFM.