Preparation of polyisocyanates containing isocyanurate groups and use thereof

A process for preparing polyisocyanates containing isocyanurate groups by partial trimerization of aliphatic and/or cycloaliphatic diisocyanates in the presence of at least one trimerization catalyst and deactivation of the trimerization catalyst after reaching the desired degree of trimerization, wherein the trimerization catalysts used comprise tetraalkylammonium alkyl carbonates of the formula (I) ##STR7## or mixtures with (quaternary ammonioalkyl) carbonates having a betaine structure and the formula (II) ##STR8## where R.sup.1, R.sup.2 and R.sup.4 are identical or different and are a C.sub.1 - to C.sub.20 -alkyl group, a C.sub.5 - to C.sub.6 -cycloalkyl group, a C.sub.7 - to C.sub.10 -aralkyl group or a phenyl group or where R.sup.1 and R.sup.2 together form a 5-membered or 6-membered cycloalkyl group or, together with a nitrogen atom, form a 5-membered or 6-membered ring which can contain an additional nitrogen or oxygen atom as a bridge member, or where R.sup.1, R.sup.2 and R.sup.4 together form a multi-membered multi-ring system which can contain one or more additional nitrogen atoms and/or oxygen atoms as bridge members,

• R.sup.3 is a C.sub.1 - to C.sub.4 -alkyl group,
• R.sup.5 is a C.sub.2 - to C.sub.20 -alkylene group, a C.sub.5 - to C.sub.6 -cycloalkylene group, a C.sub.7 - to C.sub.10 -aralkylene group or a phenylene group or
• R.sup.5 and R.sup.1 together are an alkylene group and together with a nitrogen atom as bridge member form a 5-membered to 7-membered heterocyclic ring.