Synthesis and evaluation of new hyperbranched alkyds for coatings

Abstract Novel hyperbranched alkyd resins (HBAs) were synthesized by reacting the hydroxyl end-groups of the prepared hyperbranched polyesters, based on 1,3,5-tris(2-hydroxyethyl) cyanuric acid (THECA) as a trifunctional core, with different oil fatty acids, namely, linseed, soya and sunflower oil fatty acids. Resins of different compositions of HBAs were prepared by changing either the fatty acid or the generation of the hyperbranched polyester. Their molecular structures were identified using IR and 1 H and 13 C NMR spectroscopy. The thermal stability, glass transition temperatures and rheological properties were investigated. All of the alkyd resins exhibited initial decomposition temperature at values >300 °C. The decreased Tg values of LG3, SG3 and SFG3 render them suitable for use as coatings that are applied at ambient temperature. All HBAs show Newtonian behaviour and the viscosity was ranging between 1.2 and 5.2 Pa s. Film properties of the prepared alkyd resins using different driers were determined and it has been found that all samples exhibited good adhesion, bending, impact, ductility, and high gloss, but show low hardness.