Polyurethane foams are produced by the reaction of polyol, polyisocyanate and water in the presence of catalysts and other auxiliary agents.
Catalysts play an important role not only in the control and balance between the gelling and blowing reactions, but also in the optimization of the foam properties and the curing speed during the foam formation. Tertiary amines either alone or in combination with tin octoate are most widely used catalysts in the manufacture of polyurethane foams.
Depending on their chemical structure they speed up the reaction between the hydroxyl and the isocyanate groups, accelerate the blowing reaction between isocyanate and water resulting in formation of CO2, or when blocked with carboxylic acids show delayed activity after being deblocked at elevated temperatures. Amine catalysts can accelerate the surface reaction speed and improve the surface properties of the finished goods by migrating to the foam mold surface. Those containing hydroxyl groups will react with the isocyanate groups becoming bonded to the polyurethane polymer matrix, which renders zero-emission of amine catalyst during the service life of the end product.