Patent GB-792767-A (GB)
Title: Complex grease containing hydrogenated castor oil
Filed: 1955-07-06
Abstract: A lubricating grease suitable for use at high temperatures comprises a major proportion of lubricating oil thickned with (1) a soap-salt complex of an alkaline earth metal or magnesium soap of a high molecular weight carboxylic acid having 12-30 carbon atoms per molecule and an alkaline earth metal or magnesium salt of a low molecular weight carboxylic acid having 1-6 carbon atoms per molecule, the molar ratio of low molecular weight carboxylic acid radicle to high molecular weight carboxylic acid radicle in the complex being in the range 7 : 1 to 40 : 1, and (2) hydrogenated castor oil, the weight ratio of hydrogenated castor oil to soap in the thickener being in the range 1 : 4 to 4 : 1. Lubricating oils mentioned are mineral oils, esters of monobasic acids (e.g. the ester of C8 oxo alcohol with C8 oxo acid or the ester of C13 oxo alcohol with octanoic acid), esters of dibasic acids (e.g. di-2-ethyl hexyl sebacate or di-nonyl adipate), esters of glycols (e.g. C13 oxo acid di-ester of tetraethylene glycol), complex esters (formed, for example, by reacting 1 mol. of sebacic acid with 2 mols. of tetraethylene glycol and 2 mols. of 2-ethylhexanoic acid, or by reacting 1 mol. of tetraethylene glycol with 2 mols. of sebacic acid and 2 mols of 2-ethylhexanol, or by reacting 1 mol. each of azelaic acid, tetraethylene glycol, C8 oxo alcohol and C8 oxo acid), esters of phosphoric acid (formed, for example, by the action of 3 mols. of the monomethyl ether of ethylene glycol on 1 mol. of POCl3), halocarbon oils (e.g. polymerized chlorotrifluoroethylene), polysiloxanes, sulfite esters (formed, for example, by the action of 1 mol. of SO2Cl2 on 2 mols. of the methyl ether of ethylene glycol), carbonates (formed, for example, by reacting C8 oxo alcohol first with ethyl carbonate and then with tetraethylene glycol), mercaptals, formals, polyglycol ethers and mixtures of these.  The soap-salt complex may be formed by co-neutralization of the corresponding acids in the presence of lubricating oil, but this lubricating oil must be a non-saponifiable oil such as mineral oil, though saponifiable lubricating oils may be added subsequently.  Suitable high molecular weight carboxylic acids are stearic acid, mono- or poly-hydroxy stearic acids, arachidic acid, oleic acid, ricinoleic acid and hydrogenated fish oil and tallow fatty acids, while suitable low molecular weight acids are formic, acetic, propionic, furoic, acrylic, adipic and lactic acids.  The lubricating grease may contain additional ingredients such as additional thickeners (e.g. polyethylene), antioxidants (e.g. phenyl alpha naphthylamine and N-lauryl-p-amino-phenol) and tackiness agents (e.g. polybutene).  In an example, the preparation of a lubricating grease from mineral lubricating oil, hydrogenated fish oil fatty acids, acetic acid, hydrated lime, phenyl alpha naphthylamine and hydrogenated castor oil is described.  For comparison purposes, the preparation of another grease from the same ingredients is described, the hydrogenated castor oil in this case being allowed to react with the lime instead of being added subsequently to the formation of the soap-salt complex.