Microcellular polyurethane vibration isolator

Claim 1

A vibration isolator consisting essentially of a microcellular polyurethane elastomer having a bulk density of 0.3-0.9 g/cm 3 , a tensile strength of at least 5 kg/cm 2 , a spring constant of at least 0.1 ton/cm, a permanent compression set of 25% at the most, and a fatigue strength of 2.0 mm at the most, said polyurethane elastomer obtained by reacting in the presence of water as the blowing agent (a) an organic polyisocyanate, (b) a polyether polyol having an average number of functional groups of 2.5-3.5 and a number molecular weight of 4500-8500, and which is obtained by addition polymerizing ethylene oxide and propylene oxide with a lower aliphatic polyhydric alcohol of 2-6 carbon atoms or with a low molecular weight active hydrogen-containing compound containing at least two active hydrogen atoms, and (c) a chain extender, in such a ratio that the NCO index is 90-110 and the concentration of the chain extender, based on the total weight of the three components (a), (b), and (c) is 0.4×10 -3 to 2.0×10 -3 equivalent/gram.