| abstract |
The present invention relates to a process for the effective removal of residual monomeric aliphatic isocyanate from a reaction mixture comprising aliphatic polyisocyanate comprising (i) providing a reactor containing a scavenger comprising a zeolitic material, wherein the zeolitic material comprises SiO 2 and optionally X 2 O 3 in its framework structure, wherein X is a trivalent element; (ii) providing a reaction mixture comprising aliphatic polyisocyanate and monomeric aliphatic isocyanate; (iii) contacting the scavenger in the reactor with the reaction mixture provided in (ii) at a temperature lower than the boiling point of the residual monomeric aliphatic isocyanate for obtaining a product comprising aliphatic polyisocyanate with a reduced monomeric aliphatic isocyanate content, wherein if the zeolitic material comprises X 2 O 3 , the zeolitic material has an SiO 2 to X 2 O 3 molar ratio higher than 2.8:1, preferably higher than 5:1, more preferably higher than 30:1. |