| abstract |
Disclosed are rigid polyurethane-polyisocyanurate foams prepared from polyisocyanates, polyols, trimer catalysts and a blowing agent mixture comprising (i) a halocarbon, and (ii) an organic carboxylic acid, and, optionally water. n The foams have excellent aged K-factor values at fluorocarbon levels reduced by up to 75 percent over prior art materials. |