Patent GB-648763-A (GB)
Title: A process for the manufacture of aluminum soap greases
Filed: 1947-06-12
Abstract: Aluminium soap lubricating greases are made by forming a mixture of a lubricating oil, an aluminium soap and an aliphatic or cycloaliphatic amine containing 5-36 carbon atoms in the molecule or a fatty acid salt of an aliphatic or cyclo-aliphatic amine, said salt containing 10-36 carbon atoms in the molecule, or a heterocyclic nuclear amine containing 5-24 carbon atoms in the molecule or a fatty acid salt of a heterocyclic nuclear amine, said salt containing 10-28 carbon atoms in the molecule, continuously feeding the grease in a hot fluid condition on to a moving horizontal heat-conducting belt (see Specification 642,948), forming a thin layer of grease thereon, passing the moving belt supporting the grease layer through one or more cooling zones, and cooling the grease while in a quiescent state by subjecting the grease in said cooling zone or zones to the action of a heat-absorbing medium until a smooth substantially homogeneous grease gel is produced.  The proportion of amine or amine salt in the grease may be 0.05-0.3 per cent by weight and the proportion of aluminium soap may be up to 5.5-6.0 per cent by weight.  The amine, if free, preferably contains 10-18 carbon atoms in the molecule and if a fatty acid salt of an amine is used, the salt preferably contains 10 to 23 carbon atoms in the molecule.  Specified amines include octylamine, laurylamine, myristylamine, palmitylamine, stearylamine, tri-butylamine, or di- or tri amylamine, mono- or di-cyclohexylamine, diN,N1-dodecylethylenediamine, alkylated morpholines, pyridine and hydrogenated pyridine.  Alternatively fatty acid salts of any of the above amines may be used, e.g. amyl amine oleate.  The fatty acids used to make the aluminium soap may be any of the fatty acids commonly used in grease manufacture, e.g. saturated fatty acids containing 14-24 carbon atoms in the molecule and unsaturated fatty acids containing 18-22 carbon atoms in the molecule.  The fatty acid may be stearic acid, 12-hydroxy stearic acid, 9,10-di-hydroxy stearic acid, 4-hydroxy palmitic acid, iso-stearic acid, iso-palmitic acid, ricinoleic acid, oleic acid, linoleic acid, hydrogenated fish oil fatty acids, palm oil fatty acids, and cotton seed oil fatty acids. When aluminium stearate is used it may be the mono-, di- or tri-stearate.  The lubricating oil is preferably a mineral oil having a viscosity of 100-2000 S.S.U. at 100 DEG  F.  The grease may contain a small proportion of polyisobutylene, e.g. 0.3-0.5 per cent by weight, and/or 0.05-0.25 per cent by weight of gum rosin or abietic acid.  The grease may be cooled in a single continuous operation to a temperature below that at which the grease gel is transformed from a rubbery to a buttery consistency e.g. to below about 105-185 DEG  F.  The cooling period may be below one hour, e.g. 3-20 minutes and the flow of the cooling medium may be countercurrent to that of the grease.  The thickness of the layer of grease on the cooling belt may be about 0.1-1.0 inch. The layer of grease may be passed through two successive cooling zones, one cooling zone (the "hot" cooling zone) being adjacent the hot end of the cooling belt, and the other cooling zone (the "cold" cooling zone) being adjacent the discharge end of the cooling belt. The ratio of the velocity of the cooling medium in the cold zone to that in the hot zone may range from 1 : 1 to 10 : 1.  The cooling medium may be air and the grease may be cooled from about 350 DEG  F. to about 80-90 DEG  F.  In an example, 55 lbs. of aluminium di-stearate and 110 lbs. of mineral oil (viscosity 100 S.S.U. at 100 DEG  F.) are mixed and heated to about 350 DEG  F.  830 lbs. of mineral oil having a viscosity of 2000 S.S.U. at 100 DEG  F., 0.5 lbs. of mono-stearylamine and 3 lbs. of a 7 per cent solution of polyisobutylene in mineral oil are added at about 325-355 DEG  F. and the hot homogeneous liquid grease fed on to the belt of the cooling apparatus to a depth of about one-third of an inch.  The grease is cooled to about 95 DEG  F. in 10 minutes by means of a current of air having an initial temperature of about 80 DEG  F. Specification 563,429 also is referred to.