| 摘要 |
PROBLEM TO BE SOLVED: To reduce the amount of a dehydrohalogenated by-product present in cell walls and obtain a rigid polyurethane foam by reacting an organic polyisocyanate with a specific organic substance in the presence of a specified foaming agent and spedifying the heat transfer constant. SOLUTION: (A) An organic polyisocyanate with preferably about 25-35% NCO content is reacted with (B) an organic substance which is preferably a mixture of a polyether polyol with an ester group-containing polyol having about 200-650 OH value and >=2 isocyanate-reactive hydrogen atoms in the presence of (C) a foaming agent comprising (i) water in an amount of >=1.0 wt.%, preferably about 1.0-4.0 wt.% based on the total foam-forming mixture and (ii) 1,1-dichloro-1-fluoroethane to afford a rigid polyurethane foam having about <0.160 Btu-in./h.ft<2> deg. F. |
