Unsaturated polyester resin（UPR）, is a type of polymer formed through the polycondensation reaction between polyacids and polyalcohols. This process produces water as a by-product. Unsaturated polyester resin（UPR）is a versatile, easily moldable liquid polymer that, when cured (cross-linked with styrene using specific substances like organic peroxides, known as hardeners), retains the solid shape it takes in the mold. The resulting products exhibit exceptional strength and durability characteristics.