ORGANIC COMPOUNDS WHICH CONTAIN URETDIONE GROUPS AND BLOCKED YANATE END GROUPS

摘要

The present invention relates to a process for producing polyisocyanates containing uretdione groups and blocked terminal isocyanate groups. Organic diisocyanates are dimerized, optionally in the presence of phosphine catalysts and then reacted with a blocking agent and optionally a chain lengthening agent. The proportions of blocking agent and chain lengthening agent are chosen such that less than all the isocyanate groups are reacted with chain lengthening agent and such that there are substantially no free isocyanate groups left. The invention also relates to latent polyisocyanate produced by this process, i.e. those containing ?rethdione groups and blocked terminal isocyanate groups. The invention is also concerned with the use of such polyisocyanates to make polyurethane resins.