GB785509A - Grease composition - Google Patents

Abstract

Water-resistant lubricating greases, suitable for use over a wide temperature range, comprise a lubricating oil thickened with the calcium salts of a mixture of (I) 10-60 per cent of a straight chain alkane monocarboxylic acid containing 1-6 carbon atoms per molecule; (II) 10-80 per cent of an alkane monocarboxylic acid containing 7-12 carbon atoms per molecule and having no side chain larger than a methyl group; and (III) 2-75 per cent of a fatty acid containing more than 12 carbon atoms per molecule and containing at most one olefinic carbon-to-carbon double bond and at most one hydroxyl substitutent per molecule, all percentages being by weight. The lubricating oil may be mineral oil, an ester of an aliphatic or aromatic dicarboxylic acid such as di-(2-ethylhexyl)-sebacate or adipate or dibutyl phthalate, a silicone, a silicate ester, an ester of a phosphorus-containing acid, a fluorocarbon, or an ester of a polyalcohol with a monocarboxylic acid such as polyethyleneglycol di-(2-ethyl hexoate). Acid I may be acetic, propionic, butyric, valeric or caproic acid. Acid II may be heptanoic, caprylic, pelargonic, capric undecylenic or lauric acid of the mixed unsubstituted C-. C1- and C12 acids having methyl side chains obtained by the oxo process. Acid III may be myristic, palmitic, stearic, arachidic, behemic, lignoceric, cerotic, oleic or 9-(or 10- or 12-) hydroxystearic acid, or branched chain isomers of such acids, or mixtures of such acids. The lubricating grease may contain additional ingredients such as antioxidants (particularly amines such as phenyl alpha-naphthylamine and phenols such as 2,6-di-tert. butyl-4-methylphenol) and lubricity improving agents (particularly free fats, free fatty acids, esters of aliphatic and/or aromatic monocarboxylic acids, sulphurized fats and lead soaps), while anti-foam agents such as silicones may also be added during the preparation of the grease. In the preparation of the grease, the acids may be reacted, in the presence of the lubricating oil, with insufficient lime to complete neutralization of the acids, the mixture dehydrated and then further lime added so that the acidity is at least completely neutralized. The lime employed may be calcium oxide or hydroxide or, alternatively, calcium carbonate may be used. In the examples, greases are prepared from mineral lubricating oil, lime, acetic acid, caprylic or pelargoic acid and stearic or oleic acid. For comparison purposes, the preparation of greases from sodium, lithium or barium salts of mixed acids, and also from calcium salts of mixtures of acetic acid with only high molecular weight fatty acids, is described.