Very low density molded polyurethane foams via isocyanate-terminated prepolymers

An all water-blown, isocyanate-terminated prepolymer-derived, polyurethane molded foam having a molded density less than or equal to 1.5 lb/ft.sup.3 and a softness, as measured by 25% ILD, of less than or equal to 15 lbs, said molded foam prepared by a process comprising:

• a) providing an isocyanate-terminated prepolymer prepared by reacting an excess of one or more di- or polyisocyanates with a polyoxyalkylene polyether polyol component having a nominal, average functionality of between 2 and 8, a hydroxyl number of between about 12 and 56, and an oxyethylene content of between 0 and 30 weight percent, said polyoxyalkylene polyether component comprised of one or more polyoxyalkylene polyether polyols, such that said isocyanate-terminated prepolymer has a free NCO group content of between 12 and 22 weight percent;
• b) mixing with said isocyanate-terminated prepolymer, water as a reactive blowing agent, in an amount of 30 mol percent to 150 mol percent in stoichiometric excess, based on the free NCO group content of said isocyanate-terminated prepolymer, to form a foamable polyurethane reactive mixture;
• c) introducing said foamable polyurethane reactive mixture into a mold;
• and
• d) recovering a foamed polyurethane product.