Versatility, performance track record, easy processing, cost efficiency

Orthophthalic resins (abbreviated as “Ortho resins”) are a type of unsaturated polyester resins broadly used for making composite components. The basic chemistry of the resin backbone consists of a combination of maleic anhydride, phthalic anhydrides, and different types of glycols (e.g. monopropylene glycol, monoethylene glycol, dipropylene glycol).

In the manufacturing process at AOC, these ingredients are combined into an unsaturated polyester chains through a poly-condensation reaction, and then diluted with a reactive monomer (in most cases styrene) and other ingredients to make a finished resin. Our customers combine the resin with specific peroxides, so a chemical reaction is initiated between resin backbone and the styrene, transforming the liquid into a hard and durable material.

AOC is able to tailor resin characteristics by influencing the ratio of the ingredients for the resin backbone. This allows to make resins tha cure at ambient temperature, and to optimize resin properties like heat resistance and resin ductility. In addition, resin cure profile and viscosity can be fine-tuned for the specific production process of the customer.

Ortho resins are mostly processed in combination with glass fibers and fillers, and in few cases as unfilled resin (e.g. for clear casting applications). Because of their versatility in performance and ease of processing, Ortho resins are used in Hand lay-up, Spray-up, Vacuum infusion, Casting, Filament Winding, Pultrusion and SMC BMC processes.

Consequently, Ortho resins are broadly used in Marine (boatbuilding), Wind (wind turbine blades, rotor components, nacelles), Industrial (sewer pipes, water transport, tanks), Building & Infrastructure (sanitary components, façade panels, artificial stone, profiles, electrical components).

Ortho/ NPG resins are a special type of Ortho resins featuring additional strength and improved chemical resistance. For those reasons they are broadly used in Relining applications.


AOC Products

AOC has a broad range of products based on Ortho resin chemistry in its portfolio, sold under Synolite™, Beyone™, Palatal® and Palapreg® brand names. In order to find the best product for your application, please check out the Product Selector. You can contact an AOC Technical Service representative for helping you in this process (


More Information

For additional information, please check out case studies on Eurojust (building façade panels), Fujian Hongye (fishing boats), and Brandenburger (UV cure relining).


Questions? feel free to contact us!

+41 52 6441212