Reducing the amount of coalescing aid in high performance waterborne polymeric coatings

One of the objectives of the waterborne coatings industry is to reduce or eliminate solvents out of latex paints, maintaining or increasing the mechanical performance in a way that makes industrial adaptation as plain and economical as possible. This task has been tackled by the use of temporary oligomer plasticizers (TOP) in this work. The aim of TOPs is to use oligomers to achieve the plasticisation during film formation without changing significantly the final properties of the film. The incorporation of oligomers in the polymer particles is obtained by in-situ formation with the help of a chain transfer agent added in the reactor at the end of the main polymerization step. The TOP concept is translated as well from a conventional copolymer acrylic composition to a commercial formulation with promising results. On the other hand, a study of the role of the plasticizer during film formation is carried out by measuring the chain interdiffusion rate using the Pyrene Excimer Fluorescence (PEF) technique. The reduction of the amount of co-solvent needed to produce films at room temperature by the use of TOP is therefore associated to a faster diffusion of polymer chains in the presence of oligomers.