Synthesis of Polyester‐Based Glycidyl Ether and Its Application in Enhancing Weathering Resistance of Epoxy Powder Coatings

ABSTRACT Polyester‐based glycidyl ether (PR‐EP) was synthesized by melt polycondensation of polyols and polyacids to obtain a hydroxyl‐terminated polyester resin, followed by reaction with epichlorohydrin. FT‐IR, 1 H NMR, softening‐point and epoxy‐value measurements confirmed the expected structure. After blending PR‐EP with a bisphenol‐A epoxy resin (E‐12) at various loadings and curing, the 40 wt.% PR‐EP formulation exhibited the best overall performance. Its impact strength increased from ±50 to ±100 kg·cm, pencil hardness increased from 2H to 4H, and adhesion reached grade 0. Thermogravimetric analysis revealed that the 5% weight‐loss temperature of this system was 63.7°C higher than that of pure E‐12. Accelerated weathering, boiling‐water immersion, and acid/alkali exposure tests demonstrated that the 40 wt.% PR‐EP coating retained 30% gloss after UV aging for 144 h, 70% gloss after boiling‐water treatment for 30 h, and 60% gloss after acid/alkali immersion for 30 h, respectively. The enhanced performance is attributed to the high cross‐link density and hydrophobic aliphatic chains of PR‐EP, which synergistically hinder oxygen and water ingress. This work provides a highly effective strategy for developing high‐performance outdoor epoxy powder coatings.