Patent ID: 8609887

Claim:
A process for preparing polyisocyanates comprising biuret groups from a) at least one (cyclo)aliphatic diisocyanate and/or polyisocyanate, b) at least one (cyclo)aliphatic diamine having two primary and/or secondary amino groups, c) optionally at least one acid, and d) optionally at least one solvent, e) optionally in the presence of water or at least one water-releasing compound, the process comprises: i) mixing the components a), b) and optionally c) and also optionally d) and/or e) in a mixing device, thereby forming a reaction mixture, and ii) feeding the reaction mixture obtained in i) into at least one reaction apparatus in which the reaction mixture is treated thermally, wherein the mixing device is at least one rotating fixed-bed reactor in the absence of a stator in the region of the mixture, having an acceleration acting on the liquid phase in the mixing device of at least 100 g.