A process for the production of a polyisocyanate mixture having an NCO content of 5 to 47% by weight and containing isocyanurate and allophanate groups in a molar ratio of monoisocyanurates to monoallophanates of 10:1 to 1:10 which comprises
- a) catalytically trimerizing a portion of the isocyanate groups of an isocyanate component substantially containing one or more cyclic organic diisocyanates having (cyclo)aliphatically bound isocyanate groups
- b) adding 0.01 to 0.5 moles, per mole of organic diisocyanate, of a monoalcohol containing at least one carbon atom and having a molecular weight of up to 2500 to the organic diisocyanate prior to or during the trimerization reaction of step a) and
- c) terminating the trimerization reaction at the desired degree of trimerization by adding a catalyst poison and/or by thermally deactivating the catalyst.