4,4'-Methylenebis[N-sec-butylaniline] is primarily used as a curing agent in the production of polyurethane and epoxy resins. It plays a critical role in enhancing the mechanical properties, thermal stability, and chemical resistance of these materials. In the automotive and construction industries, it is employed to manufacture durable coatings, adhesives, and sealants that withstand harsh environmental conditions. Additionally, it is utilized in the production of composite materials, contributing to the strength and longevity of products like fiberglass and carbon fiber components. Its application in the electronics industry includes the development of insulating materials and encapsulants for electronic devices, ensuring reliability and performance.