It is understood that diphenylmethane diisocyanate (MDI) is one of the important raw materials for the production of polyurethane (PU). There are only five manufacturers in the MDI industry in China, and the concentration of production capacity is relatively high. At present, the production capacity concentration and regional market concentration of enterprises in the MDI industry are relatively high, and the market concentration will continue to increase in the future.

MDI is produced by liquid phase phosgene method, and the main raw materials are aniline, liquid nitrogen and other materials. MDI is currently divided into pure MDI and polymerized MDI. In my country, aggregated MDI
Mainly used to produce PU rigid foam, semi-rigid foam, etc., widely used in refrigerators, thermal insulation materials, automobiles and construction industries. pure MDI
Mainly used in PU pulp, PU sole solution, etc. In recent years, the rapid rise of the domestic spandex industry has also increased the demand for pure MDI.

MDI is a biphenyl ring structure, which can significantly increase the hardness of the polyurethane material; in addition, there is a methylene group between the two benzene rings. Due to the internal rotation of the carbon-carbon single bond, the spatial rotation of the macromolecular chain is enhanced, making the elasticity The bulk elongation is higher and the mechanical properties are improved. Due to its excellent properties, MDI has become the most used isocyanate raw material at present.