| 摘要 |
This invention relates to a process for the preparation of cast polyurethane elastomers comprising reacting in an open mold at an isocyanate index of about 90 to about 110 (a) an organic polyisocyanate; (b) an aminocrotonate-terminated polyether having a molecular weight of from about 1200 to about 6500 and having the formula <IMG> wherein A is the m-functional group left by the removal of the hydroxyl groups of a polyether polyol having a number average molecular weight of from 1000 to 6000, R is the difunctional residue of certain aromatic diamines having the formula H2N-R-NH2 such that each free -NH2 group of the aminocrotonate-terminated polyether has a moderated reactivity toward the organic polyisocyanate, as indicated by a gel time of about 60 to about 300 seconds (measured at 90-110.degree.C in the absence of a slower reacting chain extender or crosslinker), and m is a number of from 2 to 8; and (c) a chain extending agent having a molecular weight of from 62 to 400, optionally in admixture with 0 to about 30% by weight, relative to the chain extending agent, of a crosslinking agent having a molecular weight of from 300 to about 500.
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