GB635057A - Improvements in or relating to lubricating grease compositions - Google Patents

Abstract

Lubricating greases comprise (1) a liquid lubricant base of which at least the major portion is composed of a high molecular weight, high boiling liquid diester of an aliphatic dicarboxylic acid and (2) sufficient metal soap to thicken the liquid lubricant base to a gel-like consistency. The viscosity of the diester lies within the range 40 S.U.S. at 100 DEG F. and 200 S.U.S. at 210 DEG F. and is at least 0.5 cs. at temperatutes up to 302 DEG F. The liquid lubricant base of the grease may contain a minor proportion of mineral lubricating oil, particularly when the soap is formed in situ. Not less than 50 per cent by weight of the soap consists of the soap of a fatty acid (or mixture of such) containing 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. The soap may be prepared from the free fatty acids or their glycerides. The alcohol radicals of the dicarboxylic acid diesters may be aliphatic branched chains and the diester may, for example, be di-2-ethylhexyl sebacate, di-sec-amyl sebacate, di-2-ethylhexyl alkenylsuccinates, di-2-ethoxy ethyl sebacate, di-2-(21-methoxyethoxy) ethyl sebacate, di-2-(21-ethyl butoxy) ethyl sebacate, di-2-butoxyethyl azelate, di - 2 - (21 - butoxyethoxy) ethyl alkenylsuccinates, and di-2-butoxyethyl alkenyl succinates. The esters may be derived from other dicarboxylic acids such as adipic, pimelic or alkylmaleic. The soap may be prepared from hydrogenated castor oil or 12-hydroxy stearic acid. Up to 50 per cent of the soap present may be derived from substantially saturated non-hydroxy fatty acids such as stearic acid or their glycerides. The soap metal may be sodium, calcium, barium, or aluminium. Additives such as extreme pressure agents or anti-oxidants may be incorporated in the grease. In the example, 225 grams of hydrogenated castor oil and 200 grams of mineral oil are heated with 89 grams of 46 per cent sodium hydroxide solution at 210 DEG F., 75 grams of stearic acid added and the resulting soap base dehydrated at 280 DEG to 308 DEG F. Heating is then discontinued and first 142 grams of mineral oil and then 8 grams of phenyl alpha naphthylamine and 3 grams of stearic acid added. Thereafter 877 grams of di-2-ethylhexyl sebacate are slowly added and finally 1050 grams of a blend of 71.7 per cent sebacate ester, 27.8 per cent mineral oil and 0.5 per cent phenyl alpha naphthylamine are added slowly at 194 DEG F. Specifications 601,346 and 635,058 are referred to. The Specification as open to inspection under Sect. 91 also includes references to lubricating greases in which the "oil component" wholly or partly comprises a "synthetic oleaginous compound," a term defined as embracing organic compounds which possess lubricating qualities and the majority of which are polar, with oxygen as the principal constituent of the polar group. They are said to include the aliphatic ethers, aromatic acid esters, aliphatic mono- and di-carboxylic acid esters, phosphorus acid esters, and halogenated aromatic compounds. Included in the examples of di-carboxylic acid esters are di-methylcarbitol sebacate, di-butyl carbitol alkenyl succinate and di-butylcellosolve alkenyl succinate. Iriethylidene sorbitol is also mentioned. Lithium is included among the metallic constituents of the soaps which may be used in the grease. This subject-matter does not appear in the Specification as accepted.