| abstract |
The present invention provides a low density, semi-rigid polyurethane foam made from the reaction product, at an isocyanate index of from about 100 to about 150, of at least one polyisocyanate and an isocyanate-reactive blend containing from about 15 wt.% to about 55 wt.%, based on the weight of the resin, of a difunctional or greater functionality polyether polyol, from about 3 wt.% to about 19 wt.%, based on the weight of the resin, of at least one polyether tetrol, and from about 7 wt.% to about 39 wt.%, based on the weight of the resin, of at least one non-halogenated polyester polyol in the presence of jτom about 5 wt.% to about 30 wt.%, based on the weight of the resin, of at least one non-hydroxy functional flame retardant and from about 1 wt.% to about 20 wt.%, based on the weight of the resin, of at least one cross linking agent, and optionally in the presence of one or more of catalysts, surfactants, chain extenders and blowing agents, wherein the semi-rigid polyurethane foam having a density of from about 2 to about 25 pcf meets at least a V-I class rating in accordance with UL 94 V flammability testing. The low density, semi-rigid polyurethane foams of the present invention may find use in producing lightweight, rapidly erected barriers for protection of people such as soldiers, police officers and fire fighters from pursuit by adversaries. Barriers made with the inventive foam may also be used to limit access to already secured areas. |