| 摘要 |
The present invention is directed to a new process for the preparation of mixed trimers by at least partly trimerizing the isocyanate groups of at least two organic isocyanates of a reactivity which differs in the sense of the trimerization reaction, in the presence of trimerization catalysts and optionally interrupting the trimerization reaction at the respectively desired degree of trimerization, in which process the less reactive isocyanate component is introduced, polymerization is then commenced in the presence of the catalyst with the trimerization of at least 0.1% of the isocyanate groups and the more reactive isocyanate component is finally metered into the reaction mixture thus obtained; the mixed trimers obtained according to this process; and the use of the mixed trimers having free isocyanate groups obtained by this process, optionally in a form blocked by blocking agents for organic polyisocyanates, as a starting material for the production of polyurethane plastics materials. |
