| 摘要 |
A microcellular polyurethane elastomer obtained by mixing an NCO-terminated prepolymer, an OH-terminated prepolymer and a foaming component with stirring to cause foaming and curing is disclosed, in which the NCO-terminated prepolymer is (A) a prepolymer obtained by reacting a polyester polyol (a) having a number average molecular weight of 1,000 to 3,000 and diphenylmethane-4,4'-diisocyanate (MDI) or (B) a partially crosslinked prepolymer obtained by further reacting the reaction product of polyester polyol (a) and MDI with a low-molecular weight polyol, the OH-terminated prepolymer is (A) a prepolymer obtained by reacting polyester polyol (a) with a polyisocyanate or (B) a prepolymer obtained by reacting polyester polyol (b) and/or a polyether polyol both having a number average molecular weight of 500 to 3,000 with a polyisocyanate, and the foaming component contains water as a main blowing agent, which elastomer exhibits improved resistance to fatigue failure and permanent set in a fatigue test while retaining advantages of the use of MDI.
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