Unsaturated polyesters in aqueous miniemulsion

Coating resins are driving to waterborne systems, which can be performed by primary or secondary dispersion of polymer in water. In this context, primary dispersions of polycondensation reactions und aqueous conditions are not widely studied. As shown in this study, unsaturated polyesters can be synthesized in an aqueous miniemulsion using an acidic catalyst as surfactant. The use of a saturated comonomer enables the production of stable dispersions compared to polycondensations with solely unsaturated monomers as dicarboxylic acid component. Further improvement of the dispersion stability and the yield could be obtained by lowering the reaction temperature and by using alkyl esters with reduced polarity instead of dicarboxylic acids. The product of the reaction is a lowmolecular weight polymer whose polymer latex remains stable throughout the reaction which allows further copolymerization thereafter. In-situ polymerization of graft-copolymer may offer a great opportunity by combining properties of polyester and polyacrylics.