| 摘要 |
The present invention relates to dimerization catalysts which are suitable for the dimerization of organic isocyanates by heterogeneous catalysis, wherein the catalysts contain tertiary phosphines adsorbed onto adsorbent, porous carrier materials having a particle size (90%) of 0.1 to 10 mm, a pore volume of 0.4 to 1.4 ml/g, an average pore diameter of 5 to 50 nm and a specific surface area (BET) of 100 to 700 m2/g. The present invention also relates to a process for the preparation of these catalysts by the adsorption of tertiary phosphines onto these carrier materials, optionally in the presence of inert solvents. Finally, the present invention relates to the use of these catalysts for the preparation of polyisocyanates containing uretdione and isocyanurate groups by the dimerization and trimerization of a proportion of the isocyanate groups of organic diisocyanates.
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