Process for preparing low-monomer-content TDI trimers

摘要

Catalytic trimerisation of diisocyanate containing at least80 wt.% 2,4- and/or 2,6- diisocyanatotoluene (TDI) to give an isocyanurate containing below 0.1 wt.% monomeric diisocyanate is effected while adding 0.1-25 wt.% (based on diisocyanate) of additional 2,4-TDI and ending reaction optionally by poisoning the catalyst. Solvent- and isocyanurate group-containing polyisocyanates based on 2,4- and/or 2,6-diisocyanatotoluene (TDI) and with a monomeric diisocyanate content below 0.1 wt.% are obtained by catalytically trimerizing a mixture of diisocyanate (20-80 wt.%) containing at least80 wt.% 2,4- and/or 2,6-TDI; solvent (20-80 wt.%; an alcohol component (0-20 wt.%); and a dialkylaminomethyl group-containing phenolic catalyst at 20-120degreesC while adding 0.1-25 wt.% (based on diisocyanate) of additional 2,4-TDI and ending reaction optionally by poisoning the catalyst.