Patent GB-635058-A (GB)
Title: Improvements in or relating to lithium base lubricating grease compositions
Filed: 1946-08-26
Abstract: Lithium base lubricating greases comprise an organic liquid lubricant thickened to a gel-like consistency with lithium soaps consisting of a major proportion of the lithium soap of a hydroxy fatty acid having at least 12 carbon atoms in the molecule and one or more - OH groups separated from the -COOH group by at least one carbon atom, and a minor proportion of the lithium soap of a non-hydroxy saturated fatty acid.  The liquid lubricant consists of a major proportion of a synthetic high boiling, high molecular weight oleaginous liquid having lubricating properties and being a diester of an aliphatic dicarboxylic acid or a dimethyl silicone polymer, and a minor proportion of mineral lubricating oil.  The lithium soaps may be formed from a blend of a major proportion of hydrogenated castor oil or 12-hydroxy stearic acid and a minor proportion of stearic acid. The grease may contain about 1 per cent by weight of glycerine and the liquid lubricant component of the grease may be a 3 : 1 blend by weight of di-2-ethylhexyl sebacate and mineral lubricating oil.  The diesters may be derived from adipic, pimelic, azelaic, alkenyl-succinic and alkylmaleic acids.  The alcoholic radicals of the esters are preferably aliphatic, particularly the branched chain type.  Specific examples of such esters are di-2-ethylhexyl sebacate, di-sec-amyl sebacate, di-2-ethylhexyl alkenyl succinates, di-2-ethoxyethyl sebacate, di-2-(21-methoxyethoxy) ethyl sebacate, di-methyl carbitol sebacate, (di-2-(21-ethylbutoxy) ethyl sebacate, di-2-butoxyethyl azelate, di-butyl cellosolve azelate, di-2-(21-butoxyethoxy) ethyl alkenylsuccinates, di - butylcarbitol alkenylsuccinates, di-2-butoxyethyl alkenyl-succinates and di-butylcellosolve alkenylsuccinates, the word "Cellosolve" being a Registered Trade Mark.  In an example, 16.8 pounds of 10.4 per cent lithium hydroxide solution, 9 pounds of water, 16.2 pounds of hydrogenated castor oil and 22.6 pounds of mineral lubricating oil are heated with stirring for 4 hours at 170-190 DEG  F. and 5.5 pounds of stearic acid added.  The product is dehydrated for 4 hours at 290-312 DEG  F., the temperature reduced and 12.2 pounds of mineral lubricating oil, 62.6 pounds of di-2-ethylhexyl sebacate and 196 grams of phenyl alpha naphthylamine added.  Finally, 5 pounds of a blend of 28 per cent mineral oil, 72 per cent of sebacate ester and 23 grams of phenyl alpha naphthylamine are added and the grease drawn at 166 DEG  F. Greases made in accordance with the invention are said to retain their resistance to shear upon prolonged shearing to a greater extent than other greases made by gelling non-hydrocarbon liquid lubricants.  The Specification as open to inspection under Sect. 91 comprises also lubricating greases in which the liquid lubricant component is a synthetic oleaginous compound (optionally blended with a mineral lubricating oil) having a minimum viscosity of 0.5 cs. within the lubricating temperature range, and which may be a polar compound containing oxygen as the principal polar constituent, e.g. an aliphatic ether, an aromatic acid ester, an aliphatic mono-carboxylic acid ester, or triethylidene sorbitol. Alternatively, the synthetic compound may be a phosphorus acid ester or a halogenated aromatic compound or a liquid silicone polymer.  The lithium soap may be derived wholly or in part from any soap-forming hydroxy fatty acid (or its glyceride).  Examples are given of the preparation of greases in which di-2-ethylhexyl sebacate is the sole liquid lubricant component and the lithium soap is either the stearate or the 12-hydroxy stearate.  This subject-matter does not appear in the Specification as accepted.