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 f oam blown by a non-ozone depleting agent--an alternative to chlorofluo rocarbon-has been developed. This method involves the reduction of the gas thermal conductivity for polyurethane foam by the conversion of g aseous carbon dioxide in the foam to an organic carbonate. We tried to perform the cyclization of carbon dioxide in foam with an epoxy compo und, and then the reduction of the thermal conductivity of the polyure thane foam was ascertained as carbon dioxide was chemically fixed in t he foam. Consequently, this method led to a reduction of about 10% in the thermal conductivity in comparison with that of the conventional f oam including carbon dioxide. In addition, the degree of progress of r eaction in the foam was investigated by a quantitative analysis of car bon dioxide, epoxide and the resulting cyclic carbonate in the polyure thane 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. Furthermor e, the unnecessary reactions were affected by the type of urethane cat alyst, the selection of which has been of importance in this method.