COLORLESS URETEDIONE AND ITS PRODUCTION

Colourless, isophorone di-isocyanate-based ureth:di:one (I) is obtained by (a) reacting isophorone di-isocyanate to a conversion of 10-70% at 0-60 degrees C in the presence or absence of solvent and in presence of 0.2-4 wt% of catalysts of formula P(R3)(R5)R4 (A) and (B), in which R1, R2 = 1-8C alkyl, or R1 + R2 + N = a 5- or 6-membered ring which may contain a CHMe, NMe or O group instead of CH2; R3-R5 = 4-12C (cyclo)alkyl; and then (b) isolating the product as a residue by thin film distillation of the reaction mixture without prior deactivation of the catalyst mixture. Also claimed is the above process for the production of (I). Preferably, the catalyst (A) is tributyl-, trihexyl-, trioctyl- or tridodecyl-phosphine, and catalyst (B) is 4-dimethylaminopyridine or corresponding 4-diethylamino-, 4-pyrrolidino-, 4-piperidino- or 4-(4-methyl-piperidino)-pyridines.