Method for modifying diisocyanates

The present invention relates to a process for modifying diisocyanates for preparing polyisocyanates, where the diisocyanate is reacted using a catalyst, wherein the diisocyanate used is obtained by quenching a gaseous reaction mixture in the phosgenation of diamines in the gas phase, wherein the gaseous reaction mixture comprises at least a diisocyanate, phosgene and hydrogen chloride, wherein a quenching liquid is sprayed into the gas mixture which flows continuously from a reaction zone into a downstream quenching zone, and wherein the quenching liquid is sprayed in by at least two spray nozzles which are arranged at the inlet of the quenching zone at equal intervals along the circumference of the quenching zone.