| 摘要 |
The invention relates to a novel process for preparing low-monomer-content trimers based on 2,4- and/or 2,6-diisocyanatotoluene (TDI). A catalytic trimerization is carried out in a mixture of from 20 to 80% by weight of a diisocyanate component containing at least 80% by weight of 2,4- and/or 2,6-diisocyanatotoluene, from 20 to 80% by weight of solvent, and 0-20% by weight of an alcohol component, and also phenolic catalysts containing dialkylamino-methyl groups. In the course of ongoing trimerization, in one or more steps, additional monomeric 2,v4-diisocyanatotoluene is metered in.
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