Multistage preparation of cycloaliphatic diisocyanates, useful for forming e.g. polymers, comprises reacting cycloaliphatic diamines with carbonic acid derivatives and alcohols to give cycloaliphatic diurethane and thermally cleaving

摘要

Multistage process for continuously preparing cycloaliphatic diisocyanates, comprises: reacting cycloaliphatic diamines with carbonic acid derivatives and alcohols to give cycloaliphatic diurethane and subsequently thermally cleaving the cycloaliphatic diurethane to give cycloaliphatic diisocyanates. Multistage process for continuously preparing cycloaliphatic diisocyanates, comprises: reacting cycloaliphatic diamines with carbonic acid derivatives and alcohols to give cycloaliphatic diurethane and subsequently thermally cleaving the cycloaliphatic diurethane to give cycloaliphatic diisocyanates, where the process comprises producing diurethanes in two stages, thermally cleaving the cycloaliphatic diurethane freed of low, medium and high boilers to release the desired cycloaliphatic diisocyanate, and continuously discharging a portion of a cleavage residue from a cleavage apparatus and reurethanizing the cleavage residue with alcohol and recycling the reurethanization product directly into a low-boiler separation, where unconditioned urea and/or urea equivalents produced from unconditioned urea are used.