Orthophthalic and Isophthalic Polyester Resins
Choosing the right resin for your application
Unsaturated polyester resin is widely used in composite and fiberglass products. Two well-known families are orthophthalic (Ortho) and isophthalic (Iso) resins. The choice between them should be based on the product’s service conditions, manufacturing process and the technical specifications of the individual grade.
Orthophthalic Polyester Resin
Orthophthalic resins are commonly selected for general-purpose composite applications. Suitable grades can be used for fiberglass components, coverings and moulded parts that are not exposed to severe chemical or environmental conditions.
When selecting an orthophthalic grade, important factors include viscosity, reinforcement wet-out, gel time and the properties of the cured component. Final performance depends on the resin formulation and the quality of the manufacturing process.
Isophthalic Polyester Resin
Isophthalic resins are generally considered for applications where resistance to water and chemical environments is more important. Appropriate grades may be used in tanks, pipes and industrial components exposed to moisture or specified fluids.
However, the term “isophthalic” alone does not mean resistance to every chemical. The fluid, concentration, operating temperature and duration of exposure must be checked against the technical information and chemical resistance guide for the specific grade.
Which Type Is Right for Your Project?
For general-purpose applications, a suitable orthophthalic grade may meet the production requirements. Where water contact, environmental durability or chemical resistance takes priority, evaluating isophthalic grades is a practical starting point.
The final choice should take account of the manufacturing method—such as hand lay-up, spray-up, filament winding or other processes—and the resin’s technical data sheet. Component design, reinforcement type, curing conditions and, where required, post-curing also affect the finished product’s performance.
Resin Supply through VIP Global Co.
At VIP Global Co., we can source and arrange shipment of various resin types, including orthophthalic and isophthalic polyester resins, through our commercial partners in Iran or our representative office in the United Arab Emirates.
To review suitable options and receive an offer, please send us your application, required technical specifications, order quantity and delivery destination.
