Lithium soap is a soap consisting of a lithium salt of a fatty acid.[1][2] Sodium-based and potassium-based soaps are used as cleaning agents in domestic and industrial applications, whereas lithium soaps are used as components of lithium grease (white lithium).
| Examples of Lithium salts of fatty acids |
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Lithium soaps are produced by saponification of triglycerides, using lithium hydroxide or lithium carbonate as the saponification agent. Lithium soaps are used as lubricant components and form-release agents at relatively high temperatures.[3] The main components of lithium soaps are lithium stearate and lithium 12-hydroxystearate.[4]
Lithium grease
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Lubricating greases are commonly formulated as mixtures of an oil and a lithium soap thickener.[5] Some formulations include PTFE or other substances, such as molybdenum disulfide.
Lithium grease adheres particularly well to metal, is non-corrosive, may be used under heavy loads, and exhibits good temperature tolerance. It has a dropping point of 190 to 220 °C (370 to 430 °F) and resists moisture, so it is commonly used as lubricant in household products, such as electric garage doors, as well as in automotive applications, such as constant-velocity joints. Lithium greases using a thickener formed by reacting a simple lithium soap with an acid are known as lithium complex greases and have higher dropping points as well as improvements to other properties.[6]
References
edit- ^ Tharwat F. Tadros (1 April 2014). An Introduction to Surfactants. De Gruyter. pp. 6–. ISBN 978-3-11-031213-3.
- ^ Arno Cahn (30 May 2003). 5th World Conference on Detergents: Reinventing the Industry : Opportunities and Challenges. The American Oil Chemists Society. pp. 182–. ISBN 978-1-893997-40-0.
- ^ The Significance of Tests of Petroleum Products: A Report. ASTM International. 1934. pp. 152–. GGKEY:FWTS3ZUUWJL.
- ^ Uttam Ray Chaudhuri (19 April 2016). Fundamentals of Petroleum and Petrochemical Engineering. CRC Press. pp. 89–. ISBN 978-1-4398-5161-6.
- ^ Angelo Nora, Alfred Szczepanek, Gunther Koenen, "Metallic Soaps" in Ullmann’s Encyclopedia of Industrial Chemistry 2005 Wiley-VCH, Weinheim. doi:10.1002/14356007.a16_361
- ^ David Turner. "Grease Selection: Lithium vs. Lithium Complex". Machinery Lubrication. Retrieved 2020-11-26.