| 摘要 |
<p>The instant invention is directed to a process for the production of moldings based on polyurethanes comprising reacting organic polyhydroxyl compounds with organic polyisocyanates in quantitative ratios corresponding to an NCO/OH equivalent ratio of from 0.8:1 to 1.2:1, wherein said polyhydroxyl compounds are selected from the group consisting of: (a) alkoxylation products of ammonia containing 3 hydroxyl groups and having a molecular weight of at least 149 and a hydroxyl group content of at least 12% by weight, (b) alkoxylation products of aromatic polyamines containing at least 4 hydroxyl groups and having a molecular weight of at least 284 and a hydroxyl group content of at least 12% by weight, (c) phenol/formaldehyde condensates containing at least 3 phenolic hydroxyl groups and having a phenolic hydroxyl group content of at least 12% by weight, (d) mixtures of (a), (b), and (c), and (e) mixtures containing at least 25% by weight of at least one of the polyhydroxyl compounds mentioned in (a), (b), and (c) with other polyhydroxyl compounds optionally containing ether or ester groups and having a molecular weight in the range of from 62 to 3000, said mixture having a mean OH functionality of at least 2.7 and a hydroxyl group content of at least 12% by weight, wherein said reaction is conducted at a temperature from 0 DEG to 100 DEG C. to form a solid, powderable and fusible reaction product which contains free isocyanate and hydroxyl groups, but which will not react further in said temperature range.</p> |
