CFC and HCFC- free rigid insulating foams having low K-factors and decreased flammability

摘要

Polyurethane/polyisocyanurate rigid foams with low K-factors and enhanced flame-retardant properties as measured by the Butler Chimney test are produced from an organic polyisocyanate and a polyol at an isocyanate index of 90 to 500 in the presence of a blowing agent composition comprising pentane and a fully halogenated brominated halocarbon in a mole ratio of from 10:1 to 1:2. The polyurethane preferably derives from a polyester polyol and polymeric MDI to a foam of isocyanate index 200-350. The bromohalocarbon may be dibromodifluoromethane.