What drives the global supply-demand balance for HDI monomer?

What drives the global supply-demand balance for HDI monomer?
Global HDI production remains tightly controlled by a handful of players—Covestro, Vencorex, Asahi Kasei, Tosoh, Mitsui Chemicals, and Wanhua Chemical—due to complex phosgenation technology and high entry barriers. In China, HDI monomer capacity reached about 185,000 tonnes in 2021, up 37% from 2017, with all incremental 50,000 tonnes coming from Wanhua. However, actual output lagged at roughly 90,000 tonnes, constrained by technology bottlenecks and phosgene feedstock restrictions, leaving the market structurally tight. Downstream demand is broadening beyond traditional polyurethane coatings into electrocoatings, ultra-wear-resistant flooring, wind blade and tower protective coatings, and photovoltaic backsheet adhesives, which should absorb future supply increases and support sustained market growth.