| abstract |
Polyurethane/polyisocyanurate foam insulation described herein is derived from a composition that contains an organic polyisocyanate, an isocyanate reactive material containing at least about 20% by weight, based on the total weight of the composition, of an aromatic polyester polyol, a hydrocarbon blowing agent, a first catalyst selected from the group consisting of a carboxylate salt of an alkali metal, a carboxylate salt of an alkaline earth metal, a carboxylate salt of a quaternary ammonium, and combinations thereof, and a second catalyst comprising a non-reactive tertiary amine, wherein a molar ratio of the first catalyst to the second catalyst is less than about 1.25, the composition gels quickly, and the composition has an isocyanate index greater than about 175. Such an insulating foam has a ratio of thermal conductivity at 75° F. to thermal conductivity at 25° F. between about 0.98 and about 1.10. |