Surface thermal-curing phosphorus-containing coated rigid polyurethane foam with highly-efficient flame retardancy and reinforced mechanical property

A phosphorous-containing HEMAP–co–GMA (HPG) prepolymer was successfully prepared by the ring-opening reaction of glycidyl methacrylate (GMA) and 2–hydroxyethyl methacrylate phosphate (HEMAP) as monomers, and flame retardant HEMAP–GMA copolymer (HPG) coating on the surface of rigid polyurethane foam (RPUF) was further fabricated by free-radical thermal-curing. The HPG coating endowed RPUF excellent flame retardancy and fire hazardous safety. The HPG coated on RPUF (HPG/RPUF) reached UL94 V–0 rating, and the limited oxygen index value of the HPG-2/RPUF improved from 19.0 % of RPUF to 27.8 %. The cone calorimetric test results showed that the total heat release and mean peak heat release rate values of the HPG-2/RPUF reduced by 79.6 % and 54.6 % compared to those of RPUF, respectively. The flame–retardant mechanism of HPG/RPUG was speculated the synergistic flame retardant effect between the barrier of the dense char layer and the inhibition of phosphorus–containing free–radicals. The three–dimensional crosslinked HPG coating not only provided HPG/RPUF excellent water resistance, but also enhanced compressive properties and heat–insulation. The highly efficient flame–retardant HPG coating has great potential in fire protection of the heat insulation foams.