Thanks to the various advantages they offer, many companies are currently conducting research and development activities on calcium sulfonate based greases, which are preferred in different applications today. Among these companies, Akoni Kimya supports its activities in this field with two projects within the scope of their R&D works. The company currently continues their efforts to develop these greases.
Overbased chemicals called calcium sulfonate (TBN numbers> 350 mg/KOHgr) are used in lubricants and greases as rust inhibitors and corrosion inhibitors. Especially in greases and engine oils, the usage rate of these chemicals can go up to 10 percent when some performance criteria are considered.
Calcium sulfonate-based greases have excellent technology for grease applications with high temperature, water, high or shock loads. These greases have superior rust and abrasion protection and high load carrying capacity, and they show excellent mechanical stability even at high dropping point and in the presence of water. Unlike other types of greases, these performance characteristics are achieved without any additional raw materials.
It is observed that calcium sulfonate complex-based greases generally act as problem solvers in heavy-duty applications. They are successfully used in marine, iron and steel plants, paper mills, off-road, construction and mining equipment and even in food processing industries.
Overbased calcium sulfonates contain a large amount of amorphous calcium carbonate dispersed in the sulfonate matrix. After the gelation process in the presence of suitable chemicals such as alcohols and acids with high boiling point and in the appropriate temperature range, the amorphous calcium carbonate is converted into crystalline calcite. Since the particle size of the dispersed calcite phase is in the nano range (4-5 nm), it forms a stable gel structure that is strong enough to provide an extremely high surface area and grease-like consistency. It should be noted that the pressure should be 50 psi on average in the appropriate reactor. At this point the grease still contains water due to the reaction and must be dehydrated to produce lubricating grease. This is often referred to as calcium sulfonate gel or calcium sulfonate grease.
In performing this process, overbased calcium sulfonates must be prepared by starting a reaction with appropriate acids in the presence of calcium oxide and carbon dioxide by stoichiometric calculations in a typically closed and pressurized (50 psi) reactor.
After the conversion in the chemistry of calcium sulfonate greases, complexity occurs by the addition of calcium oxide or (usually) hydroxide, followed by reaction with boric acid/acetic acid and 12-hydroxystearic acid.
