ABSTRACT
This chapter discusses the chemical processes leading to scorching in polyurethane foams and reviews the various types of antioxidants developed as scorch inhibitors along with their mechanisms of action. Flexible polyurethane slabstock foams are prepared by reaction of an isocyanate with a polyol and water in the presence of catalysts and a blowing agent. Polyether polyols used in the manufacture of flexible slabstock foams have been stabilized for many years by the use of antioxidant systems, typically combinations of hindered phenols and secondary aromatic amines. The mandated phase-out of chlorofluorocarbon (CFC) blowing agents is having profound implications on the selection of scorch inhibitors for use in flexible polyurethane slabstock foams. The elimination of CFC’s from foam formulations has been accomplished in part by using higher levels of water, which reacts with isocyanates to form carbon dioxide, which acts as an effective blowing agent.
