MOCA (4,4’-Methylene-bis(2-chloroaniline)) is an aromatic diamine commonly used as a curing agent (chain extender) in the processing of cast polyurethane elastomers. It reacts with isocyanate-terminated prepolymers to produce elastomers with excellent mechanical strength, high hardness, good abrasion resistance, and thermal stability. MOCA has long been favored in demanding applications such as mining equipment, rollers, wheels, and industrial parts where durability is critical.