F+L Week 2019 | Dr. Jun Dong | Enhancing the performance of lubricants through synergistic antioxidant mixtures and base oil selection
Faced with the challenges of improving performance and prolonging service life, formulation developers today commonly use antioxidant mixtures with synergistic interactions. One classic example is a nonylated (C9) diphenylamine antioxidant in combination with a hindered phenol ester synthesized with iso-octanol (C8). This antioxidant system has found use in many types of lubricants, including automotive engine oils. Besides iso-octanol, there has been interest in recent years in other types of alcohols with different hydrocarbon chains (i.e., length and isomerization).
The hindered phenol esters derived from these alcohols are generally less well known in the lubricants industry, as are their applications. This paper examines the performance of some of the common homologs and their synergistic interactions with the nonylated diphenylamine. Test results suggest that the antioxidant performance can be influenced by alcohol type, base oil and formulation, as shown in bench test methods. All these can be important considerations when it comes to the development of high-performance lubricants.