Multistep process for the continuous preparation of cycloaliphatic diisocyanates

摘要

A multistage process (P1) for continuously preparing a cycloaliphatic diisocyanate (D1) involves reacting a cycloaliphatic diamine with carbonic acid derivative and alcohol to give cycloaliphatic diurethane; thermally cleaving cycloaliphatic diurethane to give (D1); continuously discharging a portion of cleavage residue; reurethanizing discharge with alcohol; removing high boiler components; and recycling reurethanized stream into process. A multistage process (P1) for continuously preparing a cycloaliphatic diisocyanate (D1), by reacting a cycloaliphatic diamine with a carbonic acid derivative and an alcohol to give a cycloaliphatic diurethane and subsequently thermally cleaving the cycloaliphatic diurethane to give (D1), involves: performing formation of cycloaliphatic diurethane in two stages; cleaving cycloaliphatic diurethane freed of low and medium boilers to release (D1); continuously discharging a portion of the cleavage residue from the cleavage apparatus; reurethanizing the discharge with alcohol; removing high boiler components; and recycling the reurethanized stream into process. An independent claim is included for a process for producing polyurethane involving reacting (D1) obtained by the process (P1) with a polyol (preferably a diol).