Abstract: The present invention is directed to a process for the production of polyisocyanates containing isocyanurate groups by trimerizing a portion of the isocyanate groups of hexamethylene diisocyanate using N,N,N-trialkyl-N-benzyl-quaternary ammonium hydroxides as the trimerization catalyst, terminating the trimerization reaction at the desired degree of trimerization by adding a catalyst poison and/or by thermally deactivating the catalyst and removing unreacted hexamethylene diisocyanate to a residual content of at most 0.2% by weight, characterized in that a) the hexamethylene diisocyanate used as starting material is freed from carbon dioxide to a residual content of less than 20 ppm (weight) and b) the catalyst is used in a quantity of less than about 0.03% by weight, based on the weight of the hexamethylene diisocyanate used.

Abstract: Novel microcapsules are characterized in that the walls thereof consist of reaction products of crosslinking agents with iminooxadiazinedione isocyanates or the walls thereof contain such reaction products. A process for the production of such microcapsules has also been found, as have carbonless copying papers containing such microcapsules.

Abstract: The present invention relates to a polyisocyanate mixture containing isocyanate trimers provided thati) 30 to 100 mole percent of the trimers are iminooxadiazine diones B and ##STR1## ii) 0 to 70 mole percent of the trimers are isocyanurates A iii) less than 10 mole percent of the polyisocyanate mixture is of the uretone imine structural type, andiv) the ratio of the sum of the mole percents of trimers A and B to the mole percent of uretdiones is greater than 4:1whereinR.sup.1, R.sup.2 and R.sup.3 are the same or different and represent the groups obtained by removing an isocyanate group from an aliphatic, cycloaliphatic, aromatic and/or araliphatic isocyanate having an NCO content of less than 70% and/or their oligomers.

Abstract: A process for the production of polyisocyanates containing isocyanurate groups by the catalytic trimerization of a mixture of low molecular weight isocyanate components having aliphatically and aromatically bound isocyanate groups in the presence of aminosilyl compounds, the resulting polyisocyanates and their use in coating compositions.

Abstract: A process for the preparation of isocyanurate group-containing polyisocyanates in solvents which are inert towards isocyanate groups by reacting 0.2 to 1.5% of the isocyanate groups of diisocyanatotoluene with an aliphatic monohydric alcohol having 6 to 22 carbon atoms and subsequently trimerizing at least a portion of the isocyanate groups of the urethanized diisocyanates in the form of 40 to 70 wt. % solutions in lacquer solvents which are inert towards isocyanate groups, and the use of these polyisocyanates in two-component polyurethane coating compositions.