Papi 580N Isocyanate Dow Chemical PU - Isocyanates >> MDI, diphenylmethane diisocyanate >> Polymeric MDI PAPI* 580 N polymeric MDI is a polymethylene polyphenylisocyanate that contains MDI. This product has a high functionality and a relatively high viscosity. Recommended for use in polyisocyanurate rigid foams, this product imparts good resistance to heat distortion, excellent strength properties at low densities and improved humid age stability. Polymethylene polyphenylisocyanate that contains MDI. Possesses a high functionality and a relatively high viscosity. Used in polyisocyanurate rigid foams. Imparts good resistance to heat distortion, very good strength properties at low densities and improved humid age stability.