Lupranat M 50 4,4'-Diphenylmethane diisocyanate BASF-Elastogran Polyurethane (PU) - Prepolymers >> Isocyanate >> MDI based Lupranat M 50 is a solvent-free product based on 4,4'-diphenylmethane diisocyanate (MDI) and contains oligomers of high functionality and isomers. The average functionality is 2.8 to 2.9. Lupranat M 50 is principally used for the manufacture of thick insulating panels. It is also used for rigid block foams. Solvent-free product based on diphenylmethane-4,4'-diisocyanate (MDI) containing oligomers of high functionality and isomers.