Nonphosgenation methods, especially reaction between IPDA and DMC, are clean production processes with mild reacton condition as well as satisfactory conversion and selectivity.

• 传统光气法收率高；但毒性大;非光气法特别是DMC法反应条件温和；环境污染小；虽比光气法生产成本增加了5.；45%25；但仍然具有广泛的工业化应用前景。