Synthesis of PIBSI Derivatives Using Highly Reactive Polybutene and Their Friction Reducing Effects

Highly reactive polyisobutylene (HRPB) is widely used as a lubricant additive and a fuel detergent. In this study, HRPB350 was synthesized by cationic polymerization, and HRPB260 was obtained by distillation of the by-product, for example, light polymer (LP), from the HRPB350 synthesis. Polyisobutenyl succinic anhydride (PIBSA) was synthesized by the reaction of HRPB and maleic anhydride and then converted to polyisobutenyl succinimide (PIBSI) derivatives by introducing heterocyclic moieties containing S and N atoms. The new PIBSI derivatives were expected to act as friction reducing agents since these molecules contain S and N which strongly interact with metal surfaces. The friction reducing properties in Yubase 6 and DB51 base oil were evaluated using a 4-ball tester. The wear scar diameters with polyisobutenyl succinimide (PIBSI) additives are comparable to those with commercially available products such as Zn-DTP.