| 摘要 |
Disclosed as a particular isocyanate prepolymer composition particularly suitable for use in polyurethane compositions having particular applicability for producing microcellular molded polyurethane articles particularly suitable for use as sealing devices. In particular, the isocyanate prepolymer composition is the result of reacting an isocyanate blend (a) having (i) 0 to 10 pbw 2,4'-diphenylmethane diisocyanate; (ii) 30 to 80 pbw 4,4'-diphenylmethane diisocyanate; (iii) 1 to 10 pbw of a mixture of uretonimine with from 10 to 70 parts by weight of a polyol (b) having a number average molecular weight of between 1000 and 10,000, and a hydroxyl number of between 10 to 75. The resulting isocyanate prepolymer (I) has a free NCO of less than 20 and a viscosity of from 200 to 1000 cPs.
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