Intumescent flexible polyurethane foam

Abstract From the Canadian patent

Flexible, resilient polyurethane foam having improved flame retardancy and intumescent properties is prepared from a reaction mixture comprising a polyether polyol, an organic polyisocyanate a blowing agent, a surfactant, a catalyst a flame retardant, and hydrated alumina. Alternatively, the mixture also comprises a low-viscosity linear polyester. The hydrated alumina is predispersed in a mixture comprising flame retardant and low-viscosity linear polyester and alternatively a char former, and a fugitive viscosity modifier.