Process for preparing polyisocyanates containing iminooxadiazinedione groups

摘要

The present invention relates to a process for the preparation of trimerized polyisocyanates that contain at least 30 mole % of iminooxadiazinedione groups (asymmetric trimers) in the trimer mixture, by catalytically trimerizing a starting isocyanate selected from organic di- or polyisocyanates having a number average molecular weight of 140 to 600 and containing aliphatically, cycloaliphatically and/or araliphatically bound isocyanate groups in the presence of a quaternary phosphonium polyfluoride trimerization catalyst corresponding to the formulaR4P+F-n(HF)wherein R represents identical or different, optionally branched aliphatic, aromatic and/or araliphatic C1-C20 groups, or two or more R groups may also form, with one another and with the phosphorus atom, saturated or unsaturated rings and n has a value of 0.1 to 20.