| abstract |
The present invention is directed to a polyisocyanate mixture having an NCO content of 10 to 47% by weight and a viscosity of less than 10,000 mPa.s and containing isocyanurate and allophanate groups in a molar ratio of monoisocyanurates to monoallophanates of 10:1 to 1:5, wherein the allophanate groups are formed from urethane groups which are based on the reaction product of an organic diisocyanate having (cyclo)aliphatic bound isocyanate groups and an aromatic monoalcohol containing 6 to 9 carbon atoms. n The present invention is also directed to a process for the production of a polyisocyanate mixture having an NCO content of 10 to 47% by weight, having a viscosity of less than 10,000 mPa.s and containing isocyanurate and allophanate groups in a molar ratio of monoisocyanurates to monoallophanates of 0:1 to 1:5 by n a) catalytically trimerizing a portion of the isocyanate groups of an organic diisocyanate having (cyclo)aliphatically bound isocyanate groups n b) adding 0.01 to 0.5 moles, per mole of organic diisocyanate, of an aromatic monoalcohol containing 6 to 9 carbon atoms to the organic diisocyanate prior to or during the trimerization reaction of step a) and n c) terminating the trimerization reaction at the desired degree of trimerization by adding a catalyst poison and/or by thermally deactivating the catalyst. n Finally, the present invention is directed to the use of these polyisocyanate mixtures, optionally in blocked form, as an isocyanate component in the two-component coating compositions. |