Definition - What does Polyester Resin mean?
Polyester resins are unsaturated synthetic resins that form when polyhydric alcohols and dibasic organic acids react. Maleic anhydride, which has diacid functionality, is commonly used as a raw material to produce polyester resins. Polyester resins are used in bulk molding compound, sheet molding compound and laser printer toners.
Corrosionpedia explains Polyester Resin
Polyester resins act as a high performance corrosion resistant material and therefore are ideal for manufacturing tanks, vessels and pipes that contain acids, alkalis, petroleum products, chemicals, water and other materials that increase the corrosion rate of the metal surface. The purpose of resins in the polyester is to provide long-term resistance to chemical attack and to modify the polyester's properties so it can be used in high temperature operations. Corrosion resistant resins are vinyl ester resins, terephthalic and isophthalic. In the ship building industry, vinyl ester resins are mostly used to prevent the hull from blistering due to saline water.
Understanding Corrosion in Pumps and How to Deal With It