GB709985A - Improvements in or relating to soap compositions and to grease compositions containing the same - Google Patents

Abstract

Aluminium salts of a mixture of dimerized, and, if desired, subsequently hydrogenated polyunsaturated fatty acids of 18 carbon atoms and monomeric fatty acids of 12-22 carbon atoms are prepared by mixing the dimeric and monomeric acids, converting them to the sodium or potassium salts and reacting these with aqueous aluminium sulphate, chloride or other water-soluble aluminium salt, preferably at 40-75 DEG C., with vigorous agitation. Any mixture of fatty acids containing C18 polyunsaturated fatty acids may be dimerized; such mixtures include cottonseed fatty acids, sesame oil fatty acids, soybean fatty acids, dehydrated castor oil fatty acids, commercial oleic acid, tall oil fatty acids and cottonseed foots acids. The dimeric acids may be prepared by heating the methyl esters of the monomeric acids at 300-325 DEG C. for 5-24 hours or more, removing any monomer by vacuum distillation in a carbon dioxide atmosphere and saponifying, or by heating the fatty acid mixture in a closed vessel in the presence of 2-4 per cent of steam at 330-360 DEG C. under pressure, followed by removal of any unpolymerised acid by vacuum distillation. If desired, the dimerized product may be hydrogenated at 180-200 DEG C. in the presence of a nickel or copper hydrogenation catalyst. The mixed aluminium salts may be used to gel hydrocarbon lubricating oils in the manufacture of greases. In an example (2), cottonseed fatty acids are heated in a closed vessel for 6-8 hours at 330-360 DEG C. and the dimerized product is mixed with hydrogenated fish oil fatty acids. The mixed acids are converted to the sodium salts which are then reacted with aqueous aluminium sulphate to form the aluminium salts.ALSO:A soap composition comprising the aluminium salts of a mixture of 0.5 to 20 per cent. by weight of dimerized and, if desired, subsequently hydrogenated polyunsaturated fatty acids of 18 carbon atoms and 80 to 99.5 per cent. of monomeric fatty acid of 12 to 22 carbon atoms is used to gel hydrocarbon oils to form greases. The dimer acids may be prepared from cottonseed fatty acids having an iodine-bromine value of 104-7, sesame oil fatty acids of iodine value 103-9, soybean fatty acids of iodine value about 135-140, dehydrated castor oil fatty acids or any commercial mixture containing C18 polyunsaturated fatty acids such as commercial oleic acid, tall oil fatty acids and cottonseed foots acids. Any unpolymerized acid present in the dimeric acid need not be removed. If desired the dimerized product may be hydrogenated at 180-200 DEG C. in the presence of a nickel or copper hydrogenation catalyst. The dimeric acid may be converted directly to its aluminium salt or it may be mixed with the saturated or unsaturated C12-22 fatty acid and the mixture converted to the aluminium salts. It is preferred to form the sodium or potassium soaps by addition of the mixed acids to aqueous sodium or potassium hydroxide or carbonate with stirring and subsequently to react these soaps with aqueous aluminium sulphate, chloride or other water-soluble aluminium salt at 40-75 DEG C. with vigorous agitation. In making the greases, from 1 to 20 per cent. by weight of the aluminium soaps is mixed with 80 to 99 per cent. by weight of a hydrocarbon lubricating oil of viscosity 100-120 S.U.S. at 210 DEG F. and the mixture is heated to 120-140 DEG C. and slowly cooled. Glycerine or other polyhydric alcohol in amount from 1 to 50 per cent. (preferably 1 to 8 per cent) by weight of the mixed soaps may be added to the soaps prior p to mixing them with the lubricating oil. Other optional additional ingredients include the sodium, potassium and ammonium soaps of C12-22 fatty acids and antioxidants such as tetramethyldiaminodiphenylmethane. In an example (9), 4, 5 and 6 per cent. by weight of a dimeric acid prepared from linseed fatty acids of iodine value 190 is mixed with amounts of hydrogenated fish oil acids to make 100 per cent. The mixture is converted to the sodium soaps and then to the aluminium soaps. Greases are prepared from 96 per cent. by weight. of a lubricating oil of viscosity 120 S.U.S. at 210 DEG F. and 4 per cent. of the mixed aluminium soaps.