PROCESS FOR THE PREPARATION OF BLOCKED POLYISOCYANATES, AND THEIR USE IN POLYURETHANE COATING SYSTEMS

摘要

The invention relates to a process for the preparation of totally or partially blocked polyisocyanates based on a blocking agent and on a polyisocyanate containing at least two free NCO groups, if desired in the presence of a chain extender, in which the totally or partially blocked polyisocyanates are prepared by a solvent-free and continuous procedure. This reaction is carried out in a static mixer or intensive kneading apparatus or extruder. The invention furthermore relates to the use of the totally or partially blocked polyisocyanates for PUR powder coatings and solvent-containing, one-component PUR stoving enamels.