Patent ID: 7687147

Claim:
A composite article providing blast mitigation, the composite article comprising: a fixed structure including a substrate, the fixed structure being subject to blast exposure, the fixed structure being selected from the group consisting of walls, floors, roofs, exterior ceilings, interior ceilings, dikes, dams, reservoirs, containment walls, Jersey barriers, barricades, bunkers, bridges, roadways, aqueducts, flumes, beams, columns, and piers; and a polyurethane-polyurea layer bonded to the surface of the substrate and oriented in a direction of anticipated blast exposure to provide blast and fragment protection, the polyurethane-polyurea layer including a reaction product of (a) an isocyanate component comprising a toluene diisocyanate prepolymer having from about 50% to about 90% of a toluene diisocyanate, by weight of the toluene diisocyanate prepolymer, and a polyol having a functionality from about 2 to about 3 and being selected such that the toluene diisocyanate prepolymer has an NCO group content from about 2.5% to about 12%, and (b) an isocyanate-reactive component, the reaction product being the result of impingement mixing by plural component spray equipment using pressures between about 2,000 psi and about 3,000 psi and temperatures in the range of about 145° F. to 190° F., the polyurethane-polyurea having the following characteristics: a gel time between 5 and 9 seconds, a tack-free time between 10 and 16 seconds, a tensile strength between 4,109 psi and 4,295 psi, and a tear strength of between 520 pli and 578 pli.