| 摘要 |
This invention relates to a process for the production of rigid and semi-rigid foams at low isocyanate levels, and to the foams produced by this process. The process comprises reacting a polyisocyanate component with an isocyanate-reactive component, in the presence of at least one blowing agent, at least one surfactant and at least one catalyst. Suitable isocyanate-reactive components are characterized as having a solids content of at least 40% by weight, and an overall hydroxyl number of the remaining liquid, non-solids portion of at least 160. In addition, the isocyanate-reactive component comprises at least 50% by weight of a polymer polyol having a solids content of at least 30% by weight and in which the base polyol has a hydroxyl number of at least 75.
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