| abstract |
A polyisocyanate-based rigid closed-cell foam is made by reacting an organic isocyanate with a polyol composition in the presence of a blowing agent, where the polyol composition contains at least: a) an aromatic amine initiated polyoxyalkylene polyether polyol having an hydroxyl number of 200 meq polyol/g KOH or more; b) an aliphatic amine initiated polyoxyalkylene polyether polyol having an hydroxyl number of 200 meq polyol/g KOH or more; and c) an aromatic polyester polyol having an hydroxyl number of 200 meq. polyol/g KOH or more, preferably in an amount of 18.0 weight percent or less based on the weight of the polyol composition. The blowing agent is selected from the group consisting of cyclopentane, HFC's and HCFC's and mixtures thereof and is preferably present in an amount of 5.0 weight percent or more based on the weight of the polyol composition. Preferably, the blowing agent is soluble in the polyol composition without sacrificing, and advantageously whilst improving, the thermal insulation and dimensional stability of the resulting polyurethane foam. |