Patent GB-743571-A (GB)
Title: Lubricating oil composition
Inventor: MORTON RONALD WILLIAM
IPC: C10M169/00
Filed: 1951-03-02
Abstract: A lubricant comprises a substantial proportion of a complex ester dissolved in a diester together with less than 5 per cent by weight of a soluble anti-oxidant which is either a phenol, an aromatic nitro compound, an aromatic amine, a cyclo-aliphatic primary amine, an organic sulphur compound or an organic compound containing both phosphorus and sulphur.  Complex esters are esters containing more than three monobasic acid, monohydric alcohol, polybasic acid or polyhydric alcohol residues and in which there is at least one polyhydric alcohol and one polybasic acid residue each of which has at least two of its functional groups esterified.  They are generally aliphatic and should be free from olefinic unsaturation.  The diesters are alkyl esters of aliphatic dicarboxylic acids or saturated monocarboxylic acid esters of glycols or polyglycols, e.g., those described in Specification 600,325.  Preferred complex esters are those of the formula R.1OOC.R.2COO R.3OOC.R.4COO R5 described in Specifications 666,697, 687,346 and 687,347.  Others are described in Specifications 659,103, 662,650 and 668,663.  The components of both the complex esters and diesters are preferably glycols and polyglycols of 2-60 carbon atoms, alcohols of up to 30 carbon atoms, dicarboxylic acids of 2-20 and monocarboxylic acids of up to 30 carbon atoms.  The diester-complex ester blends may be obtained by mixing or by reacting the required components as in Specifications 687,347 or 683,803, preferably to give products of viscosity 1.5-30 c.s. at 210 DEG F.  Anti-oxidants specified include mono-, di-, or tri-hydric phenols, and particularly alkyl and alkoxy-substituted phenols, and bis-phenols; nitro-phenols, nitro-benzenes, and nitro-naphthalenes; prim., sec., tert. and mixed aromatic amines, including diamines and aminophenols; cyclo-aliphatic primary amines, e.g., cyclohexylamine; thio-alcohols, thioamides, thiophenes, thiazoles, thiophenols, amine and phenol sulphides, and, in particular, thio-diphenylamine; thiophosphates, and reaction products of phosphorus and sulphur or phosphorus sulphides with terpenes or other hydrocarbons, natural or mineral oils, waxes, fats, esters or complex esters.  Thus the lubricant ester itself may be treated with phosphorus and sulphor.  Examples illustrate the inhibiting effect of 2, 6 - ditertiary butyl - 4 - methyl phenol, phosphosulphurized a pinene or dipentene and P2S5-treated ester lubricant on blends of a complex ester from 2-ethyl hexanol, sebacic acid and polyethylene glycol in molar ratio 2:2:1, and dinonyl sebacate.  Other inhibitors exemplified are catechol, homo catechol 2, 21-methylene bis (4methyl-6-tert. butyl phenol), 2-amino-4nitro-phenol, thio-diphenylamine dicyclohexylamine, and phenyl-b -naphthylamine. Additional components include other synthetic lubricants, e.g., polyoxyalkylene monohydroxy compounds and polymers of glycols, mineral or fatty oils dyes, detergents, e.g., petroleum sulphonates, and metal deactivators, e.g., N,N1-disalicylidene - 1, 2 - diamino - propane (or ethane). The oils are also of use as working or electrical oils or hydraulic fluids.  Reference has been directed by the Comptroller to Specification 687,346.