| 摘要 |
The present invention relates to a process for the production of trimerized polyisocyanates containing 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 quaternary ammonium and phosphonium fluoride trimerization catalysts corresponding to the formula R4E+F- (I), wherein E represents N or P and 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 nitrogen or phosphorus atom, saturated or unsaturated rings, in which the catalysts are i) present in pure form, ii) blended with solvating agents S for the fluoride anion, wherein S is selected from protic compounds having a pK a value of greater than 2 (determined in H2O at 25.degree.C) or oxalic acid, provided that the molar ratio of organic acid to fluoride ion, F-, does not exceed 20 and provided that S is not HF or an alcohol having a functionality of 2 or more, or iii) blended with water, wherein the molar ratio of water to fluoride ions (F') does not exceed a value of 10.
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