Impact energy-absorbing urethane foam
AssigneeMcCord Corporation
InventorKirby E. L. Flanagan
Life of this patent
Estimating the term…
Abstract
An impact energy-absorbing, relatively low density, urethane foam for use in automobile bumpers has a high content of urea linkages and is relatively temperature insensitive, i.e. gives approximately the same physical performance over a wide range of temperature. The foam is water blown in a closed mold from a quasi-prepolymer system. The pack factor is preferably in the range of 1.5 to 8 and the molded density is in the range of 5 to 20 lbs./ft..sup.3. The foam formulation is based on a polyol of a poly (oxypropylene/ethylene) triol reacted with a styrene/acrylonitrile monomer mixture which triol thus modified is reacted with (1) a 50 to 150 equivalent weight polyol cross linker of 2 to 6 functionality, (2) a MDI or TDI/glycol or triol quasi-prepolymer and (3) some water.
Claims3
An impact energy-absorbing urethane foam made from the following formulation:
- ______________________________________ Parts by Weight ______________________________________ Polymer Polyol 70 to 90 Cross linker 10 to 30 Water 1 to 5 Prepolymer To yield 90-115% Index Catalyst 0 to 2 ______________________________________
- wherein:
- said polymer polyol having a molecular weight in the range of 4000 to 8000 and comprising in the range of 2 to 6 parts of a poly (C.sub.1 -C.sub.4 oxyalkylene) triol reacted with one part of a vinyl aromatic/olefinic C.sub.2 -C.sub.6 nitrile monomer mixture;
- 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 selected from the group consisting of MDI and TDI and (b) a polyol selected from the group consisting of a 100 to 1000 molecular weight triol and a 100 to 200 molecular weight ether glycol and has a free isocyanate content in the range of 20 to 35 percent;
- and
- said urethane foam being prepared in a closed mold at a pack factor in the range of 1.5 to 8 and having a density in the range of 5 to 20 lbs./ft..sup.3, a specific energy at 50% C/D greater than 25 in.-lbs./in..sup.3, a temperature index -20.degree./140.degree. F. of less than 2.5 and at least 90% recovery at 70.degree. F. after multiple impact.
Dependencies are inferred from the claim text.