epoxypolyester

Epoxypolyester resin, commonly called epoxy-modified polyester or epoxy polyester resin, is a thermosetting resin formed by blending epoxy resins with unsaturated polyesters. The epoxy component contributes improved adhesion, chemical and moisture resistance, and thermal stability, while the polyester component provides toughness, processability, and cost efficiency. In typical formulations, a diepoxide or glycidyl-functional resin is mixed with a liquefied unsaturated polyester resin; a vinyl monomer such as styrene may be used to enable crosslinking of the polyester backbone, and the blend is cured with hardeners such as amines or anhydrides to form a crosslinked network.

Properties include good adhesion to metals and fibers, chemical resistance, and balanced mechanical performance; the relative content of epoxy and polyester controls toughness, hardness, and heat-age resistance. Epoxypolyesters often cure at ambient to moderate temperatures and can be formulated to achieve favorable tack-free times in coatings. However, they may have higher volatile organic compound emissions due to styrene or other diluents and can be more sensitive to UV aging if not stabilized.

Applications include protective and marine coatings, corrosion-resistant coatings for industrial equipment, and fiber-reinforced composite parts such as boats, tanks, and automotive components. They are chosen when a combination of good adhesion, chemical resistance, and cost-effective processing is required.

See also: epoxy resin, unsaturated polyester resin, vinyl ester resin.