Polyester resin

Unsaturated polyester resins (UP) are thermoset materials. They are usually condensation polymers of alcohols that are used as Casting materials, knifing fillers and in fibre-reinforced plastics. The double bonds of the unsaturated resins are displaced with reactive diluents (such as styrene) and are cured by being mixed with peroxides.

When cured, polyester resins usually have a clear to milky dull appearance. Depending on their composition, they can have a consistency ranging from soft to hard. Polyester resins are heat resistant and electrically insulating. They mostly exhibit good Resistance to gasoline, oil and weak acids and alkalis, however they are dissolved by strong acids and alkalis, esters and chlorinated hydrocarbons.

Polyester resins are processed using compression moulding and Injection moulding and can be laminated in fibre-plastic compounds. They can be used, for example, to manufacture casings, insulation components and guttering.

In their dissolved form, polyester resins are used as paint resins (binders) and carrier substances for pigments. They are dissolved in organic solvents when used for these purposes. Glass fibre-reinforced polyesters are used to manufacture the rotors of wind turbines, among other applications.