Resins and prepolymers

These materials are the binders of paints, adhesives, composites, laminates, foundry moulds, wood panels and printing inks. Epoxy resins combine with hardeners for coatings, adhesives and composites, phenolic and amino resins bond wood panels and laminates, and unsaturated polyesters form fibreglass parts with styrene and a peroxide initiator.

Key specifications depend on chemistry, for example epoxy equivalent weight and viscosity for epoxies, free formaldehyde and solids content for amino resins, acid value and styrene content for polyesters, and hydroxyl value for polyols. Resins have a limited shelf life, especially those that contain reactive diluents or catalysts, so check the date of manufacture and storage temperature. Formaldehyde emissions limits apply to wood-based panels in many markets.