Low density energy management urethane foam

An impact energy-absorbing urethane foam made from the following formulation:

• ______________________________________ Parts by Weight ______________________________________ Polymer polyol 70 to 90 Polybutadiene polymer 10 to 120 Crosslinker 10 to 40 Water 1 to 5 Prepolymer To yield 90-115% Index Catalyst 0 to 2 ______________________________________
• wherein:
• said polymer polyol has a molecular weight in the range of 4000 to 8000 and comprises in the range of 2 to 6 parts of a poly (C.sub.2 -C.sub.4 oxyalkylene) triol reacted with one part of a vinyl aromatic/olefinic C.sub.3 -C.sub.7 nitrile monomer mixture;
• said polybutadiene polymer is a hydroxy terminated polybutadiene homopolymer having a molecular weight in the range of 2000 to 4000, a functionality in the range of 2 to 3, and an equivalent weight in the range of 750 to 1750;
• said crosslinker is a polyol having a functionality in the range of 2 to 6 and an equivalent weight in the range of 50 to 150;
• said prepolymer is a reaction product of (a) an aromatic diisocyanate having one isocyanato group per aromatic nucleus and (b) a polyol having a molecular weight in the range of 100 to 1000, a functionality in the range of 2 to 6, an equivalent weight in the range of 30 to 150, and said prepolymer has a free isocyanate content in the range of 20 to 35 percent;
• and
• said urethane foam being prepared in a closed mold and having a density in the range of 4 to 15 lbs./ft..sup.3, a specific energy at 50% C/D greater than 15 in.-lbs./in..sup.3 at 70.degree. F. and 7 PCF, a temperature index -20.degree./125.degree. F. of less than 5 and suffering less than a 3% impact set when impacted to a strain of 75% at 70.degree. F. after allowing recovery for 30 minutes at 70.degree. F.