Patent GB-642410-A (GB)
Title: Lubricating grease composition
Filed: 1947-05-29
Abstract: Polymers of esters of acrylic acid and its homologues, of which isobutyl methacrylate is specified, may be included as optional constituents in lubricating greases comprising a lithium soap and a thioether derivative having the general formula <FORM:0642410/IV (a)/1> wherein R1, R2, R3 and R4 are hydrocarbon radicals.  The lithium soap may be a lithium salt either of a fatty acid, preferably saturated and containing twelve or more carbon atoms, or of acids from natural products, a number of which are specified such as tallow, seed-oils and naphthenic acids from petroleum.  The thioether derivative has, preferably, similar ester groups R1 and R4, and similar radicals R2 and R3.  R1 and R4 are preferably satur ated non-aromatic radicals containing 4-11 carbon atoms of which many are specified, trimethylacetic and 2-ethylhexoic being preferred, or may be higher molecular weight radicals of which the specified classes include mono-olefinic and naphthenic acid radicals. R2 and R3 are preferably straight chain saturated aliphatic radicals forming a primary linkage with the sulphur atom.  Under these conditions the formula of the thioether derivative becomes: <FORM:0642410/IV (a)/2> in which preferably m is 2-4 and n is 3-10.  Other ingredients which may be included in the grease are oxidation inhibitors of the phenolic or arylamine types, free fatty acids, and fatty acid metal salts.ALSO:Thioethers of the formula CH3(CH2)n COO(CH2)mS(CH2)mOOC(CH2)nCH3, where n is 3-10 and m is 2-6, are prepared by reacting hydrogen sulphide with an olefinic alcohol and esterifying the product.  In an example, allyl alcohol is heated with hydrogen sulphide in an irradiated bomb to give bis-(g -hydroxypropyl) sulphide, which is then heated with 2-ethylhexoic acid in toluene in the presence of p-toluenesulphonic acid.  Many other acids for use in the esterification stage are specified.  The formation of the sulphides may be promoted by catalysts, such as organic peroxides, e.g. ditertiary butyl peroxide, lauryl peroxide, benzoyl peroxide, 2,2-bis-(tertiary butyl peroxy) butane and tertiary butyl hydroperoxide.ALSO:A lubricating grease comprises a lithium soap and a thioether derivative having the general formula <FORM:0642410/III/1> wherein R1, R2, R3 and R4 are hydrocarbon radicals.  The lithium soap may be a lithium salt either of a fatty acid preferably saturated and containing twelve or more carbon atoms, or of acids from natural products, a number of which are specified, such as tallow, seed-oils, and naphthenic acids from petroluem.  The thioether derivative has, preferably, similar ester groups R1 and R4 and similar radicals R2 and R3.  R1 and R4 are preferably saturated non-aromatic radicals containing 4-11 carbon atoms of which many are specified, trimethyl-acetic and 2-ethylhexoic being preferred, or may be higher molecular weight radicals of which the specified classes include mono-olefinic and naphthenic acid radicals. R2 and R3 are preferably straight-chain saturated aliphatic radicals forming a primary linkage with the sulphur atom.  Under these conditions the formula of the thioether derivative becomes <FORM:0642410/III/2> in which preferably m is 2-4 and n is 3-10.  Other ingredients which may be included in the grease are polymers of esters of acrylic acid and its homologues, of which isobutyl methacrylate is specified; also oxidation inhibitors, free fatty acids, and fatty acid metal salts. Examples are given of greases comprising 90 per cent bis-(gamma-2-ethylhexoyloxypropyl)-sulphide (or bis - (gamma - trimethylacetoxypropyl) - sulphide or bis-(8-naphthenoxypropyl)-sulphide) and 10 per cent lithium stearate. The preparation of the thio-ethers is described (see Group IV (b)). These greases provide lubrication at both high and low temperatures and do not decompose in the presence of excessive moisture or at relatively high temperatures.