Patent GB-778567-A (GB)
Title: Metal soap-salt complexes, and lubricating grease compositions containing them
IPC: C10M169/00
Filed: 1956-02-22
Abstract: The invention comprises a dehydrated soap-salt complex including at least one divalent metal soap of a C12-C30, preferably C18-C22 aliphatic carboxylic acid, at least one metal soap of a C3-C10, preferably C6-C9 carboxylic acid, and a divalent metal salt of acetic acid, wherein the difference between the average number of carbon atoms of the first and second acids is at least seven, the mol. ratio of acetic to the other acids is at least 4 : 1, preferably 7-25 : 1, and the average saponification number of the other acids is 290-450. If the C3-C10 acid is polycarboxylic, the saponification number is taken as the equivalent weight of KOH in mgs. over the gram equivalent of the acid.  The mol. ratio of C3-C10 to C12-C30 acids is preferably from 0.5-10 : 1.  Specified C3-C10 acids include straight and branched chain saturated aliphatic acids, including oxo acids; hydroxy-acids, e.g. glyceric, lactic, citric; aromatic acids, e.g. benzoic, hydroxy-benzoic, toluic, phthalic, terephthalic; heterocyclic, e.g. furoic, thiophene carboxylic. The C12-C30 acids may be derived from natural or synthetic fatty material and include saturated hydroxy, and unsaturated acids.  The average saponification number should not exceed 280.  The acetic acid may be glacial or an aqueous solution of about 60-99.9 wt. per cent.  The metal components are preferably divalent metals, e.g. alkaline earth metals, magnesium, and zinc.  Copper, iron, nickel or cobalt are also specified.  A monovalent metal, e.g. lithium, may be present as a salt of the C3-C10 acid.  The complexes may be incorporated in lubricating oils (see Group III).  They may be prepared by neutralizing a mixture of the acids with, e.g., hydroxides or carbonates of the metals, if desired in the oil or other medium. Heating to above about 400, preferably 450-550 DEG  F., is necessary to dehydrate and form the complex.  Alternatively, the separate salts may be at least in part preformed, mixed, and heated to the necessary temperature.  A lubricating grease may be prepared by warming the oil, base, and C12-C30 acid to melt the latter, adding the other acids and, when the reaction subsides, heating above 400 DEG  F. After cooling to about 250 DEG  F., antioxidant, e.g. phenyl a -naphthylamine, is added, the grease further cooled and homogenized. Alternatively, the C3-C10 acid is added initially with the C12-C30. The complexes may be recovered from their dispersions or solutions by extracting the dispersing medium with a solvent.  Acetic acid is generally used in an amount of up to or more than twice that of the other acids.  Examples describe the preparation and properties of mineral oil base greases, the metal base used being hydrated lime, the C3-C10 acid o-phthalic, C5-C8 oxo, lactic, thiophene carboxylic, isobutyric, caprylic and/or capric, benzoic, hydroxy-benzoic, furoic or citric acid or phthalic anhydride, and the C12-C30 acid stearic, lauric or "Hydrofol Acid" (hydrogenated fish oil acid).ALSO:Lubricating oil compositions comprise a dehydrated soap-salt complex including at least one divalent metal soap of a C12-C30, preferably C18-C22 aliphatic carboxylic acid, at least one metal soap of a C3-C10, preferably C6-C9 carboxylic acid, and a divalent metal salt of acetic acid, wherein the difference between the average number of carbon atoms of the first and second acids is at least seven, the mol ratio of acetic to the other acids is at least 4 : 1, preferably 7-25 : 1, and the average saponification number of the other acids is 290-450.  If the C3-C10 acid is polycarboxylic, the saponification number is taken as the equivalent weight of KOH in mgs. over the gram equivalent of the acid.  The mol ratio of C3-C10 to C12-C30 acids is prefer ably from 0.5-10:1. Specified C3-C10 acids include straight and branched chain saturated aliphatic acids, including oxo acids; hydroxy-acids, e.g. glyceric, lactic, citric; aromatic acids, e.g. benzoic, hydroxybenzoic, toluic, phthalic, terephthalic; and heterocyclic acids, e.g. furoic, thiophene carboxylic.  The C12-C30 acids may be derived from natural or synthetic fatty material and include saturated, hydroxy, and unsaturated acids.  The average saponification number should not exceed 280.  The metal components are preferably divalent metals, e.g. alkaline earth metals, magnesium, and zinc.  Copper, iron, nickel or cobalt are also specified.  A monovalent metal, e.g. lithium, may be present as a salt of the C3-C10 acid.  The complexes may be incorporated in mineral or synthetic lubricating oils to about 5-40 wt. per cent to give greases.  Said oils should be of specified viscosity, pour point, flash point and V.I., and may be of hydrocarbon, polymerized hydrocarbon, ester, complex ester, formal, mercaptal, polyalkylene oxide, or silicone type.  The soap-salt complexes may be prepared by neutralizing a mixture of the acids with, e.g. hydroxides or carbonates of the metals, if desired in the oil or other medium.  Heating to above about 400, preferably 450-550 DEG F., is necessary to dehydrate and form the complex. Alternatively, the separate salts may be at least in part preformed, mixed, and heated to the necessary temperature.  A lubricating grease may be prepared by warming the oil, base, and C12-C30 acid to melt the latter, adding the other acids and, when the reaction subsides, heating above 400 DEG F. After cooling to about 250 DEG F., anti-oxidant, e.g. phenyl  -naphthylamine, is added, the grease further cooled and homogenized.  Alternatively, the C3-C10 acid is added initially with the C12C30.  The complexes may be recovered from their dispersions or solutions by extracting the dispersing medium with a solvent.  Acetic acid is generally used in an amount of up to or more than twice that of the other acids, and the lubricating greases contain 4-20 per cent acetic, 0.5-8 C3-C10 and 0.5-10 C12-C30 acids. Additives such as oxidation inhibitors, metal deactivators, extreme pressure agents, dyes, and deodorants may be incorporated. Examples describe the preparation and properties of mineral oil base greases, the metal base used being hydrated lime, the C3-C10 acid o-phthalic, C5 or C8 oxo, lactic, thiophene carboxylic, isobutyric, caprylic and/or capric, benzoic, hydroxy-benzoic, furoic or citric acid or phthalic anhydride and the C12-C30 acid stearic, lauric or "Hydrofol Acid" (hydrogenated fish oil acid).