Improvement of thermal insulation for polyurethane foam by the conversion of carbon dioxide to an organic carbonate compound

A new method to improve the thermal insulation of polyurethane rigid foam blown by a non-ozone depleting agent--an alternative to chlorofluorocarbon-has been developed. This method involves the reduction of the gas thermal conductivity for polyurethane foam by the conversion of gaseous carbon dioxide in the foam to an organic carbonate. We tried to perform the cyclization of carbon dioxide in foam with an epoxy compound, and then the reduction of the thermal conductivity of the polyurethane foam was ascertained as carbon dioxide was chemically fixed in the foam. Consequently, this method led to a reduction of about 10% in the thermal conductivity in comparison with that of the conventional foam including carbon dioxide. In addition, the degree of progress of reaction in the foam was investigated by a quantitative analysis of carbon dioxide, epoxide and the resulting cyclic carbonate in the polyurethane foam. It was observed that unnecessary reactions, which consumed epoxide other than for the fixation of carbon dioxide, existed in the process of urethane polymerization. The main unnecessary reaction was presumed to be a side reaction of epoxide with isocyanate. Furthermore, the unnecessary reactions were affected by the type of urethane catalyst, the selection of which has been of importance in this method.