| 摘要 |
The present invention relates to prepolymers, comprising (a) a polymethylene polyphenylene polyisocyanate; and (b) a polyether polyol having an average hydroxyl equivalent weight of a least about 700; wherein the resulting prepolymer has an average viscosity of between about 400 to about 2000 centipoise at 25 degree C. The prepolymer is useful, for example, for the production of polyurethane foams and, more particularly, to medium density flexible foams having superior flow characteristic and fast demold times.
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