Patent GB-778468-A (GB)
Title: A process for incorporating water-soluble solids in lubricating greases
Inventor: MOORE HOWARD DANIEL
IPC: C10M177/00
Filed: 1955-12-05
Abstract: A water-soluble solid, such as a corrosion inhibitor or an extreme pressure agent, is incorporated in lubricating grease by emulsifying an aqueous solution of the solid in a lubricating oil to form a water-in-oil emulsion in the presence of an oil-soluble emulsifying agent which is an organic salt of a polyvalent metal or a partial ester of a polyhydric alcohol, dehydrating the emulsion by rapid evaporation of the water present and mixing the resultant suspension with a lubricating grease.  Water-soluble corrosion inhibitors mentioned are alkali metal nitrites, chromates, phosphates, iodates, arsenites, carbonates, hypochlorites, silicates, chlorates and perchlorates (particularly sodium or potassium nitrite or arsenite, sodium or lithium chromate, and sodium carbonate or bicarbonate); ammonium or amine nitrites, chromates, phosphates and iodates (particularly dicyclohexylammonium nitrite and ammonium chromate); and boric acid or borates such as borax.  Water-soluble extreme pressure agents mentioned are hydroxy, fatty acids (e.g. glycollic, lactic, 1-ethylidene lactic, ethylene lactic, alpha-hydroxy caproic, acetonic, leucic and alpha-hydroxy valeric acids), polycarboxylic acids (e.g. oxalic, succinic, maleic, aconitic, glutaconic and citraconic acids), poly-hydroxy fatty acids (e.g. glyceric, arabonic, gluconic, galactonic, talonic and mannoaic acids), hydroxy polycarboxylic acids (e.g. citric, tartaric, tartronic, malic and saccharic acids), organic salts (e.g. sodium acetate or benzoate), amides (e.g. urea, acetamide, thiourea, succinimide and maleimide), and amino acids (e.g. glyane, alanine, cysteine, glutamic acid and aspartic acid).  The lubricating oil may be mineral oil or a synthetic oil such as a polymerized olefin, an alkylated aromatic hydrocarbon, or silicone or an ester such as di(2-ethylhexyl) sebacate.  Organic salts of organic acids, which may be employed as oil-soluble emulsifying agents, are alkaline earth metal salts of fatty acids (e.g. stearic acid), aromatic carboxylic acids (e.g. alkyl salicylic acids), naphthenic acids or sulphonic acids (e.g. naphthasulphonic acids).  Highly basic calcium naphthasulphonates and alkyl salicylates are especially suitable. Partial esters of polyhydric alcohols, which may be used as emulsifying agents, include glycerol mono-oleate, mono-stearate or mono-ricinoleate, diethylene glycol mono-laurate, mono-oleate or mono-stearate, sorbitol mono- or di-oleate and the polyoxyethylene sorbitol esters of fatty, resin or naphthenic acids.  Mixtures of such emulsifying agents, and also mixtures of polyvalent metal naphthasulphonates with polyvalent metal salts of alkyl phenols, may also be employed.  The lubricating grease, to which the suspension is added, comprises a lubricating oil (e.g. mineral oil, silicone fluid or high boiling ester), and a thickening agent (e.g. a soap such as an alkali metal or alkaline earth metal soap of a fatty acid or hydroxy fatty acid, particularly lithium or sodium stearate, or hydroxy stearate, or an inorganic collid such as silica or clay).  In the examples, an emulsion of aqueous sodium nitrite in mineral lubricating oil, prepared with the aid of a blend of basic calcium naphthasulphonate and basic calcium alkylsalicylates (the alkyl groups containing 14-18 carbon atoms) as emulsifying agent, is dehydrated and the resulting suspension is added to a grease prepared from mineral lubricating oil, lithium soap of hydrogenated castor oil and phenyl alpha-naphthylamine.