Technology to Improve the Grease Making Process By Gareth Fish, PhD CLS CLGS and Chris Hsu, PhD The Lubrizol Corporation, Wickliffe, Ohio, USA
Abstract
The process to manufacture grease is as important to grease properties as are the base oil, thickener, and the additives used to enhance performance. Grease producers manufacture greases using a wide variety of processes. This can be attributed to the availability of the basic raw materials for grease making and differences in the plant and equipment. Provided that the response of each variable is known, grease making is a controlled acid / base chemical reaction process. Grease makers strive to optimize their process for each thickener type based upon an understanding of the process variables. This paper will discuss technologies that can enable grease producers to improve and enhance their grease making process. The technologies under discussion are additives to: improve the grease yield without compromising the general properties of the grease; reduce oil bleed at both storage and elevated temperatures; and enhance the dropping points of lithium soap thickened greases. Also discussed are methods to reliably manufacture high dropping point lithium complex greases in a variety of base oils, including vegetable oils and synthetic esters.
Introduction
The process to manufacture grease is as important to grease properties as are the base oil, thickener, and the additives used to enhance the performance properties
(1). Grease producers manufacture greases using a wide variety of processes in a wide variety of equipment. This can be attributed to the availability of the basic raw materials for grease making and differences in the plant and equipment. According to the EGLI REACH Consortium (2) >30 types of lithium soap greases were registered by grease makers both within the European Union and by multi-national lubricant companies. The essentials of grease making have not changed since the days of Klemgard (3). One or more fatty acids are reacted with a slight excess of base or bases, to produce a salt or salts and water. The water is stripped out and the saponiἀcation reaction is ἀnished by the application of additional heat. For simple soaps it is typically desirable to fully melt the simple soap followed by recrystallization to achieve optimum properties, and for complex greases that the reaction is driven to or as close to completion as possible, as the more complete the reaction is the better the thickening and typically, the higher the dropping point. Over the decades there have been numerous NLGI papers and presentations on how to improve the grease making process. Some focused on improved manufacturing plant and equipment, such as Graham, et. al. (4) and Krol (5); while other papers have covered improved processing techniques for lithium greases such as Polishuk (6) and more recently, Morgan et. al. (7).
- 20 VOLUME 79, NUMBER 4
