There are two primary aromatic diisocyanates: toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI). TDI is used primarily in the production of flexible foams. MDI, the second type of diisocyanate, comes in two forms: Pure MDI and polymeric MDI (PMDI). Pure MDI is used in the production of a variety of polyurethane products like elastomers, sealants, adhesives and coatings. PMDI is a highly versatile product used to produce a wide variety of rigid, flexible, semi-rigid and polyisocyanurate and thermoset foams.

Aliphatic diisocyanates (ADI) are specialty intermediate chemicals used primarily to make durable coatings, adhesives, sealants and elastomers. Generally, they are considered to be specialty materials used in significantly smaller quantities than the aromatic diisocyanates. In total, ADIs represented less than five percent of overall isocyanate consumption in the North American polyurethane industry*. ADIs are typically not sold directly for consumer use. Rather, they are sold primarily to industrial customers who use them as binders or hardeners during manufacturing processes.