| 摘要 |
<p>Rigid polyurethane foams having low thermal conductivity values are produced by reacting an organic polyisocyanate with an organic material having at least two isocyanate reactive hydrogen atoms and an OH value of from about 200 to about 650 in the presence of a blowing agent. The blowing agent is a mixture of 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123) or dichlorofluoroethane (HCFC-141b) and from about 0.1 to about 1.0% by weight (based on total weight of the foam forming mixture) water. The foams obtained are characterized by a thermal conductivity of less than about 0.130 Btu-in./hr.ft<2> DEG F, preferably less than about 0.120 Btu-in./hr.ft<2> DEG F. These foams are particularly useful as insulation materials.</p> |
