Elimination of Amine Emissions from Polyurethane Foams: Challenges and Opportunities

Polyurethanes are a unique class of plastic in the sense that independent manufacturers buy liquid polyols and isocyanates and then react them in the presence of catalysts, surfactants and other additives in widely varying processing schemes to make the final commercial product. In some manufacturing scenarios, there is a growing concern about worker exposure to volatile organic chemicals (VOC) such as the amine catalysts. Emissions from manufactured articles that contain polyurethane components are also a concern. The polyurethane industry is continuing its legacy of successfully reducing the amount of volatile organic chemicals released from its operations. Examples of this include the total elimination of the classical chlorofluorocarbon blowing agent from flexible foams and the replacement of volatile antioxidants with less migratory ones. Today, many of the classes of ingredients commonly used in preparing polyurethanes are available in low-fogging or low VOC grades. The next big challenge being addressed by the industry is the elimination of amine catalyst vapors. This is important for both VOC and odor concerns. The catalyst suppliers have responded by introducing a variety of new, non-fugitive (sometimes called reactive) amine catalyst compositions. Their success at reducing amine emissions while providing catalytic activity is widely reported in the literature. Difficulties associated with reactivity profile adjustment, higher usage levels and losses in certain foam physical properties suggest that an improved level of technology is still needed. This paper will present a review of work The Dow Chemical Company is doing to develop flexible foam grades of polyether polyol that help reduce and in some cases eliminate catalysts while improving process. Comparative data will be presented to illustrate the utility of these new polyols in helping the polyurethane industry continue to reduce volatile emissions.