| 摘要 |
PCT No. PCT/US92/04954 Sec. 371 Date Jan. 27, 1994 Sec. 102(e) Date Jan. 27, 1994 PCT Filed Jun. 11, 1992 PCT Pub. No. WO92/22595 PCT Pub. Date Dec. 23, 1992.This invention relates to a process of preparing polyurethane polymers by reaction of an isocyanate composition having an isocyanate equivalent weight of from 180 to 300 and comprising in from at least 50 weight percent a prepolymer, with an active hydrogen-containing substance in the presence of water which provides for at least 50 mole percent of the total blowing requirement. The prepolymer is obtained by reacting a molar excess of a polyisocyanate comprising, in from at least 70 weight percent, 4,4'-methylene diphenylisocyanate with an isocyanate-reactive composition containing (a) a branched diol or triol having a molecular weight of from 60 to 300, and (b) a polyoxyalkylene polyol or mixtures thereof having an average functionality of from 2 to 4 and a molecular weight of from 3000 to 12000, wherein the parts by weight ratio of (a):(b) is from 0.01:1 to 0.25:1.
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