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Alkyd Resin Emulsification – A New Solution for Waterborne Formulations |
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Waterborne enamels have become a more interesting topic of research over the recent years because the regulatory constraints and VOC restrictions have limited the use of solventborne paints. There are lines of research and commercial products for wood and metal substrates that switched alkyds to acrylic polymers to formulate waterborne enamels, however, for applications that require high gloss, penetration into the porous substrates and high adhesion, these paints usually does not deliver the same performance of alkyd-based enamels. This is one of the reasons that has driven researchers to find alternatives to stabilize alkyds in water as emulsions. The emulsification process usually demands high-energy input, usually obtained from high-shear equipment, due to the high interfacial tension between the immiscible liquid phases. During the stirring of the mixture, the surface area increases as well as the energy of the system, which is the reason why it is so unstable. The emulsifiers – like surfactants – are added to adsorb at the interface between the liquid phases and decrease their interfacial tension and the energy of the system. In addition to that, they also adsorb at the particles surface and form a film that can prevent coagulation or coalescence in the emulsion. A mechanically strong and elastic film helps stabilizing the particles. Therefore, the higher the surfactant’s efficiency for decreasing the interfacial tension between the liquid phases and for adsorbing at the particle surface, the lower is the content of surfactant needed and the energy required to generate emulsions containing small droplets of the dispersed phase in the continuous phase. This work discuss the inversion emulsification process, presents OXIMULSION® 9000 – a new APE-free series of surfactants especially designed for alkyd emulsification in low-shear equipment with low dosage – and compares the environmental performance of a solvent-based enamel against a waterborne one during its life cycle. |
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