Diphenylmethane diisocyanate

Diphenylmethane diisocyanate, commonly known as 4,4'-MDI or MDI (CAS 101-68-8), is a diisocyanate monomer and building block used in the synthesis of polyurethane-based materials. It carries no assigned E-code and is identified under EC number 202-966-0.

In rigid and flexible polyurethane foam production, MDI reacts with polyols through isocyanate-hydroxyl addition, forming urethane linkages that determine the mechanical and thermal properties of the final matrix. It also functions as a cross-linking agent in two-component adhesive and sealant systems, where its bifunctional isocyanate groups create covalent bonds between substrates or polymer chains.

MDI is supplied in flake form and is subject to REACH regulation (Regulation EC 1907/2006), with mandatory exposure controls due to its respiratory sensitisation classification. Procurement should confirm SDS compliance and authorisation status under SVHC provisions. Standard packaging includes steel drums and IBCs; minimum order quantities vary by grade.