Calcium-sulfonate complex greases are widely used in applications in the pulp-and-paper, marine and steel-manufacturing sectors. Within an ever-volatile lithium market, calcium-sulfonate greases are increasingly seen as a reliable alternative to lithium-based greases.
However, typical methods for preparing high-performance calcium-sulfonate grease complexes require hazardous chemicals, such as acetic acid and isopropyl alcohol (IPA), which require special environmental, health and safety (EHS) considerations, and even different handling equipment in some cases. To avoid such processing and handling challenges, Afton Chemical Corp. (Richmond, Va.; www.aftonchemical.com) has patented a new production process for calcium-sulfonate greases that will help to ease the transition away from lithium-based greases, while also trying to minimize EHS concerns. “Afton’s patented process for manufacturing calcium sulfonate complex grease uses HiTEC 557, a 300 TBN calcium sulfonate, along with complexing agents, promoters and other standard grease raw materials. Unlike conventional processes, Afton’s process does not use aggressive acids like acetic acid. It is also brings value by being highly repeatable, with very little batch-to-batch variation in quality and yield, and decreases production time compared to other conventional calcium-sulfonate complex grease processes,” explains Alyson Wilson, industrial marketing specialist at Afton Chemical.
The key to the new process is a specialized promoter material, which replaces IPA, while still exhibiting similar transparency, brightness and performance properties. “This new promoter system is used to convert amorphous calcium carbonate into its crystalline form, which causes the rheology of the mixture to gel,” says Wilson. The process has now been expanded to industrial-scale production and is being deployed by grease manufacturers commercially.