| abstract |
An impact energy-absorbing, low density urethane foam for use in automobile bumpers has good moldability and is relatively temperature insensitive, i.e. gives approximately the same physical performance over a wide range of temperatures. This foam is characterized by its good multiple impact performance and low compression set values. The foam is water blown in a closed mold from a quasi-prepolymer system. The molded density is preferably in the range of 5 to 10 PCF. The foam formulation is based on a polymer polyol of a poly (oxypropylene/ethylene) triol reacted with a styrene/acrylonitrile monomer mixture which triol thus modified is reacted with (1) a roughly 1/5 to 1.5/1 weight amount of a hydroxy terminated polybutadiene homopolymer based on polymer polyol, (2) a 50 to 150 equivalent weight polyol crosslinker of 2 to 6 functionality, (3) a MDI glycol or triol quasi-prepolymer, and (4) some water. |