Fully overbased calcium sulfonate customisable grease for optimum performances
OVERBASED CALCIUM SULFONATE GREASES
A grease consists of three components: a thickener, a base oil and additives. They are classified in two main categories: soap and non-soap thickener. Properties of a finished grease are directly related to the nature of the thickener: dropping point, water resistance, mechanical stability, extreme pressure resistance, operating temperature etc. (Figure 1)
Soap thickeners are the product of the reaction between a metallic hydroxide and a fatty acid coming from vegetable or animal oils. Soap greases are described as sponges where the base oil is entrapped in the thickener network that slowly releases in use, providing lubrication.
Overbased calcium sulfonate greases (OBCaS, figure 2) are premium greases for high load and high temperature applications, suitable for extreme environment and particularly adapted for marine applications thanks to their resistance to water and their intrinsic anticorrosion performances.
The one step process from SEQENS
Calcium sulfonate greases developments started some decades ago and several patents describe conversion of overbased calcium sulfonate (precursor) with total base number (TBN) ranging from 300 to 500, to grease containing calcite particles.
In 1960, McMillen patented calcium sulfonate greases obtained via a two-step process where a highly amorphous overbased calcium sulfonate was prepared in a mineral or synthetic oil and then transformed in a second step with acids, lime and suitable promoters: amorphous calcium carbonate was converted into the desired crystalline calcite form followed by the removal of promoters and water.
In 1980s, a new process was developed for OBCaS greases with a one-step route that will later on become the key solution to formulate OBCaS greases which SEQENS has industrialized more than 20 years ago.
All ingredients are mixed together, sulfonic acid, base oil (vegetable, synthetic or mineral based) and lime. The finished greases are a complex mixture of calcium sulfonate, calcium carbonate under calcite form and a 100 % chosen carrier. Considering the market trends, SEQENS is studying new base stock carriers. For example, with that single step process, it becomes feasible to produce OBCaS without mineral oil-based precursors.
Cold temperature improvement with Naphtenic carrier
However, the use of OBCaS greases is limited for cold temperature applications. Naphtenic oils help in formulating greases for a wide temperature range.
By changing the carrier from Paraffinic Group I to a mix of Naphtenic and Group II, OBCaS greases from SEQENS exhibits the best cold temperature performances improvement. The enhanced performances of this new generation of new “naphtenic based” greases enabling their use on a wider type of applications than other “standard” OBCaS greases on the market.
The first OBCaS biolubricants
On another hand, the biolubricants market is growing driven by enforced regulations, especially in the USA with the VGP (2013) and thanks also to the various ecolabel guidelines implemented worldwide. These programs are attracting customers who are looking for ways to reduce adverse environmental impacts through their purchasing choices. Consumers’ confidence is strongly reinforced with these guiding standards and with the associated surveys conducted by independent third parties.
Consequently, grease producers must consider these new customers’ requirements to focus on the development of special ranges of eco-friendly greases. They can rely on national and international labelling programs based on voluntary initiative (European Ecolabel, German Blau Engel, Japanese Eco mark, Nordic Swan; USDA biopreferred program, Korean ecolabel).
By using 100% of esters carrier, OBCaS greases from SEQENS fit in the category of highly renewable and biodegradabe. They complete the wide range of biodegradable greases mostly represented by products based on lithium soaps, calcium soaps or lithium-calcium soaps, addressing the demand in Europe and in the USA for biodegradable greases performing in sensitive applications for the environment.
On one hand, use of OBCaS greases will continue to grow at a rapid rate, partly due to concern about long-term availability of lithium. End users are looking to use smaller quantities of grease in their application greases performance will be valued due to superior performance allowing extended life in use, limiting the maintenance and thus lessening needed volume. Newer equipment operated by grease end user is more compact and energy efficient, the result is that higher operating temperatures will be an issue. End users will need greases such as OBCaS that exhibit better thermal stability than lithium thickened greases. Water contamination continues to be an issue for end users in a variety of applications. OBCaS greases exhibit good water resistance that should lead to their greater use in applications where water can be a problem. OBCaS greases are favoured in high growth market such as Food processing, Marine and Steel markets.
In conclusion, being able to choose 100% of the OBCaS greases carriers with SEQENS one-step process leads to fully customisable greases and open a wide range of opportunities in term of performances optimisation, new applications as well as health, safety and environment considerations.