Lithium complex grease

Lithium cobalt dioxide, uses, 7 24 It Lithium complex greases, 15 243 Lithium compounds, 20 598-599. See also Organolithium compounds inorganic, 15 136-142 uses for, 15 134 Lithium cyanide, 8 194 Lithium 5—alumina, 2 406t... 

Modified lithium-12-hydroxy stearate in a mineral oil, as a lithium complex grease . 

Fig. 14.3 Temperature and shear rate dependences of the yield value for an NLGI 00 lithium complex grease specially formulated for automotive centralised lubrication systems...

Azelaic acid (AA), 1,9-nonanedioic acid or heptane-1,7-dicarboxylic acid, is used in manifold application areas. AA is offered in the pharmaceutical field for the treatment of acne and rosacea due to its antibacterial effect [1,2]. However, AA is much more widely applied as a monomer for the production of polymers such as alkyd resins, polyamides, and impact-proof polyesters or for the synthesis of plasticizers, lubricants, lithium complex greases, corrosion inhibitors, dielectric fluids, heat-transfer fluids, metal to glass fluxes, emulsion breakers, waxes, tobacco sheet plasticizers, hot-melt coatings and adhesives, water-soluble coating resins, hydraulic fluids, fungicides, insecticides, and so on [3-7]. 

Lithium greases can be manufactured by continuous process in a heated tube reactor. This process is convenient and problem-free for simple lithium soap thickened greases. However, lithium complex greases having much higher thickener concentrations resulted in increased difficulties during the continuous production. These difficulties include wide fluctuations in flow rates, cessation of flow and resultant downtime, and greatly reduced imit production capacity. 

A continuous process for the production of high dropping point lithium complex greases has been developed (13). Here, the conventional dibasic acid salt or the dibasic ester component is no longer used. These conventional components are substituted with a borated additive fed into the reactor downstream of the thickener formation zone. This substitution and process modification results in a significantly less problematic process and a substantial increase in production throughput (13). 

The results indicated that castor oil tris(diphenyl phosphate) as the additive could effectively reduce the friction and wear of sliding pairs in the two base greases. The tribological performances were also better than the commonly used zinc dialkyldithiophosphate-based additive package in hthium 12-hydroxystearate greases and also in lithium complex greases. 

G.L. Fagan, Continuous lithium complex grease manufacturing process with a borated additive, US Patent 9157 045, assigned to Chevron U.S.A. Inc. (San Ramon, CA), October 13, 2015. 

Since 1977 several new thickener types have become widely used, including complex (sodium, lithium, calcium or aluminium), polyurea, modified clays, and other non-soap thickeners. To bring the picture up-to-date, Risdon carried out an evaluation in 1986 of three of the newer grease types not inciuded in the previous programme. They were lithium complex, aluminium complex and polyurea. They included one EP (extreme pressure) and one non-EP grease for each type of thickener, and all were of the same consistency grade, NLGI No 2. 

Fig. 14.2 Frequency dependence of the complex shear modulus, G (x), phase angle, 5 (+), and complex viscosity, rj (v), for a lithium grease at 25°C...

The fact that lithium thickener still dominates the grease market means that any atomic spectroscopy technique to be considered should include the capability of determining the concentration of this important analyte. The complex nature of the grease sample matrix makes it difficult to get into a form that is compatible with ICP-AES. However, the elemental composition may be effectively measured if a suitable digestion technique can be developed. 

Lithium soaps are the most common thickeners used in the formulation of lubricating greases. Lithium soaps used for grease-making are classified into two types Simple soap and complex soap. 

Negative effects on stress-cracking behavior can also be caused by grease thickeners, such as metallic soaps based on lithium, sodium stearate, or lithium-12-hydroxystearate and lithium, barium, or aluminum complex soaps [965]. 

The properties of ester oils and complex esters are improved by additives, such as viscosity-index improvers of the methacrylate type. On the other hand, these ester oils are also used as base stock and additive for lithium greases (- lubricating greases). Perfluorinated alcohols (->perfluoro alkyl compounds) are sometimes built in ester oils to increase thermal stability. 

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