End‐grafting of oligoesters based on terephthalic acid and linear diols for high solids coatings

Abstract

Oligomers derived from terephthalic acid and 1,6-hexanediol or 1,10-decanediol have been chemically modified through end-grafting with succinic anhydride or trimellitic anhydride followed by glycidyl neodecanoate. The grafted oligomers are paste-like semisolids or viscous liquids at room temperature. As the grafted oligomers are heated, their viscosity goes down to a minimum, then up to a maximum, and then down again. Combined DSC, crossed polarizing microscopy, and wide-angle x-ray diffraction indicate that the grafted oligomers form crystalline domains dispersed in amorphous phase. The grafted oligomers are soluble in common organic solvents, such as toluene, at lower concentrations (<14-51 wt %) and form stable dispersions at higher concentrations. High solid coatings formulated with melamine or isocyanate resins gave glossy films with excellent combined hardness and impact resistance.