摘要：

A novel process for the preparation of modified polyisocyanates by oligomerisation of a part of the isocyanate groups of organic diisocyanates having (cyclo)aliphatically bonded isocyanate groups in the presence of organic phosphines as catalyst, discontinuation of the oligomerisation reaction at the desired degree of oligomerisation by addition of a catalyst poison and subsequent distillative removal of the majority of the excess unreacted starting diisocyanate, in which on the one hand 0.1 to 10% of the isocyanate groups present in the starting diisocyanate are converted into urethane groups by addition of an alcohol before and/or during the carrying-out of the oligomerisation reaction and on the other hand the distillation residue obtained is heated to temperatures of at least 50 DEG C in a mixture with 100 to 10,000 ppm of a peroxide; the polyisocyanates obtainable by this process and their use as isocyanate components in two-component polyurethane lacquers.

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