Bayer Aktiengesellschaft

Werner Kubitza

Winfried Dell

Dietrich Liebsch

Josef Pedain

Klaus Konig

The present invention is directed to a process for the production of polyisocyanate mixtures containing isocyanurate groups and uretdione groups in a molar ratio of about 1:9 to 9:1 by oligomerizing a portion of the isocyanate groups of hexamethylene diisocyanate using trialkyl phosphines and/or peralkylated phosphorus acid triamides as the catalysts which accelerate the dimerization and trimerization of isocyanate groups, terminating the reaction at the desired degree of oligomerization by the addition of a catalyst poison and removing unreacted hexamethylene diisocyanate to a residual content of at most 0.5% by weight, characterized in that, before addition of the catalyst, the hexamethylene diisocyanate starting material is freed from carbon dioxide to a residual content of less than 20 ppm (weight). The present invention is also directed to the polyisocyanates containing uretdione groups and isocyanurate groups obtainable by this process and their use, optionally blocked by blocking agents for isocyanate groups, as the isocyanate component for the production of polyisocyanate polyaddition products.

Process for the production of polyisocyanate mixtures containing

The present invention is directed to a process for the preparation of modified polyisocyanates containing uretdione and isocyanurate groups by the oligomerization of a portion of the isocyanate groups of organic diisocyanates containing (cyclo)aliphatically-bound isocyanate groups in the presence of organic phosphines of catalysts followed by termination of the oligomerization reaction at the desired degree of oligomerization by the addition of a catalyst poison and removal, by distillation, of at least a portion of the excess, unreacted starting diisocyanate, characterized in that

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Leverkusen, Germany

Winfried Dell