Patent ID: 8097691

Claim:
A process for preparing polyisocyanates from aliphatic and/or cycloaliphatic isocyanates, wherein the fraction of isocyanurate structures and iminooxadiazinedione structures in the polyisocyanate formed is more than 60 mol %, the fraction of uretdione structures is less than 25 mol %, and the fraction of carbodiimide structures and uretonimine structures is less than 5 mol %, based on the sum of all the types of structure formed, comprising reacting at least one aliphatic and/or cycloaliphatic isocyanate in the presence of a heterocyclic catalyst of formula (I) wherein R 1 is a non-cyclic or cyclic aliphatic C 1 -C 50 radical; and R 2 and R 3 together with the phosphorus atom, and optionally with R 1 , define a cycloaliphatic C 2 -C 20 radical.