Days of Future Passed:
A Critical Review of the Development of Highly Overbased Calcium Alkylbenzene Sulfonates J. Andrew Waynick
NCH Corporation
ABSTRACT
Highly overbased calcium alkylbenzene sulfonates have become an important component in numerous industrial lubricants including passenger car and heavy-duty diesel engine oils, metalworking fluids, and calcium sulfonate-based lubricating greases. The latter category was, by definition, not even possible without the development of these important raw materials. The development of highly overbased calcium sulfonates began in 1942 and has continued to the present. However, as far as the author can determine, this technology development has never been reviewed in any dedicated or organized way. This paper provides such a review by concentrating on the primary source involved: the U.S. Patent literature. By systematically and critically reviewing the more than 40 U.S. Patents from 1942 to 2000 that span the development of highly overbased calcium alkylbenzene sulfonates, a picture becomes visible that provides a clearer understanding of the current calcium sulfonate-based grease technologies that use these additives. It also clearly highlights a major gap in understanding of this area of additive chemistry previously not discussed in the open literature. The recognition of this gap sets the stage for future work needed to better understand overbased alkylbenzene sulfonate chemistry and provides a new tool for the development of improved calcium sulfonate-based greases. The organization of the large amount of developmental information represented in this review paper is cast within the metaphor of a typical 24 hour day, starting just before dawn and concluding with the arrival of night – appropriate since the story of most new technology development conforms to such a picture.
THE DAY BEGINS (1942-1945) Pinprick holes in a colorless sky, Let insipid figures of light pass by, The mighty light of ten thousand suns, Challenges infinity and is soon gone… Brave Helios, wake up your steeds, Bring the warmth the countryside needs. -Graeme Edge
Today’s calcium sulfonate-based greases have as their central component highly overbased calcium alkylbenzene sulfonates. However, the impetus for the original development of those materials had nothing to do with lubricating greases, but was instead related to crankcase oils for gasoline-powered passenger cars. As the performance demands for those engine oils had increased, so had the problems of piston ring sticking and varnish buildup. In the early 1940’s, the use of performance-improving additives for motor oils - 26 VOLUME 81, NUMBER 4
