Alkylated Naphthalenes for High Temperature Applications Maureen E. Hunter, Ph.D. King Industries, Inc., Norwalk, CT, USA mhunter@kingindustries.com Sachin Kumbhar Environ Specialty Chemicals Pvt. Ltd., Mumbai, India sachin@environchem.com This paper was given an honorary slot at the 2019 NLGI Meeting because the original presentation was awarded Best Technical Paper at the 2019 NLGI-India Meeting. Abstract Alkylated naphthalenes are multifunctional, high performance base fluids available in a diverse ISO viscosity range from 22 to 193 cSt at 40°C. They are typically used as a co-base stock in oil and grease formulations to replace a portion of petroleum or PAO base oil. This paper highlights some selected results for high temperature applications, including chain lubrication, an in-house panel coker test, plywood manufacturing, and greases, that show how alkylated naphthalenes extend the lifetime of high-performance lubricants by improving their thermal and thermo-oxidative stability, decreasing their volatility, and providing excellent dispersion and varnish control for system cleanliness. Introduction Alkylated naphthalenes are classified by the American Petroleum Institute (API) as part of the Group V base oil category. However, alkylated naphthalenes are rarely used as the sole base fluid. They are typically incorporated into lubricant formulations to replace a portion of a Group II, Group III, or PAO base oil. This is done to extend the lifetime of high-performance lubricants by: • • • • •
Improving the thermal and thermo-oxidative stability Enhancing the solubility and response of additives Imparting seal swell Decreasing volatility Providing varnish control for system cleanliness
Previously, many results demonstrating these performance benefits using various bench tests have been reported for liquid lubricants and greases containing alkylated naphthalenes. [1,2] Most alkylated naphthalenes also have approvals for NSF HX-1 incidental food contact. Naphthalene Ring Figure 1 shows that the alkylated naphthalene molecule consists of two fused six-member rings with alkyl groups attached. It is the electron-rich ring structure that imparts the performance enhancing properties, notably in non-polar fluids. The ability of the naphthalene ring to absorb energy, resonate, - 42 NLGI Spokesman | VOLUME 84, NUMBER 3 | July/August 2020
