Patent GB-681091-A (GB)
Title: Compounded lubricating oil
Filed: 1947-08-07
Abstract: Compounded lubricating oils contain (1) an oil-miscible metal salt of the condensation product of an aldehyde and a hydrocarbon-substituted aromatic hydroxy compound in which the hydroxyl group is attached to a nuclear carbon atom and which has an unsubstituted position ortho to the hydroxyl group, in an amount sufficient to give high-temperature detergent action in an internal combustion engine, and (2) a minor proportion, generally not exceeding 5 per cent and usually 0.2-0.4 per cent by weight of an oil-soluble anti-oxidant which is an aromatic amine containing at least two benzene rings (other than phenyl-alpha-naphthylamine and tetramethyl - diamino-diphenyl - methane), such of the sulphate ash yielded by the oil as is derived from said salt not exceeding 0.25 per cent based on the oil and being usually 0.04-0.2 per cent.  The substitutent hydrocarbon radicals of the aromatic hydroxy compound and/or the aromatic nucleus may be substituted by chlorine.  The substituents may be alkyl, cycloalkyl, or aryl groups, such as butyl to decyl, dodecyl, octadecyl, octadecylenyl, cyclohexyl, methylcyclohexyl, ethylcyclohexyl, dimethylcyclohexyl, propylcyclohexyl, trimethylcyclohexyl, dicyclohexyl, methylated dicyclohexyl, benzyl or ethylphenyl.  The aromatic nuclus may be mono or dicyclic, e.g. benzene, naphthalene, tetraline or diphenyl.  The aldehyde is preferably formaldehyde or acetaldehyde.  The metal of the salt of the resinous condensation product is preferably an alkaline earth metal but may be another polyvalent metal such as copper, zinc, aluminium, lead, iron, nickel, cobalt, manganese, chromium or tin. The salt, if difficulty soluble in oil, may be incorporated in oil as described in U.S. Specification 2,042,880 or in many cases may be dissolved in a solvent such as benzene, which may then, while adding oil, be gradually removed by passing an inert gas through the mixture at an elevated temperature.  The concentrate thus obtained may then be diluted with further oil. An example is given of the preparation of the calcium salt of a condensation product of formaldehyde and p-isooctylphenol.  The aromatic amine may contain one or more substituents, such as hydroxyl, chloro, alkoxy, hydroxyalkyl, amino, N-alkylated amino or N-alkylated amino alkylene, radicals.  Preferred anti-oxidants are the naphthylamines, primary, secondary or tertiary aryl or aralkyl amines having at least two aromatic rings, such as phenyl beta-naphthylamine, tetraline naphthylamine, alpha-alpha, alpha-beta or beta-beta dinaphthylamine, various phenanthryl, anthryl or picyl naphthylamines, xenyl naphthylamines, benzyl-phenyl naphthylamines, diphenayl - naphthyl - amines, phenyl-xenyl naphthylamines, dixenyl-naphthylamines, and various phenanthryl, anthryl or picyl phenyl amines.  In general the N-aryl substituted naphthylamines are preferred.  An example of a naphthylamine which is substituted by a second amino group is 1, 8 diamino naphthalene. Alternatively there may be used diamino diaryl alkanes such as diamino diphenyl methane, tetramethyl diamino triphenyl methane, tetra ethyl diamino triphenyl methane, diamino diphenyl ethane, and diamino ditolyl ethane, or alkylated diaryl amines such as p-ethyl diphenylamine, m-ethyl diphenylamine, p-isopropyl diphenylamine, mono-and polyamyl, hexyl, heptyl, octyl, nonyl, decyl, hexadecyl, cyclohexyl, methyl cyclohexyl and other alkyl substituted diphenylamine and p-methoxy-p1-isopropyl diphenylamine.  The lubricating oil may also contain oil-soluble salts of bases such as magnesium, calcium, strontium, barium, zinc, cadmium, aluminium, tin, chromium, nickel and cobalt (and of organic bases including primary, secondary, or tertiary amino and quaternary ammonium compounds) combined with such organic acids as fatty acids of 10-30 carbon atoms, wool fat acids, acids produced by oxidation of paraffin wax, chlorinated fatty acids, rosin acids, fatty and hydroxy fatty acids containing aromatic constituents, aromatic carboxylic acids including paraffin wax benzoic acids, alkyl salicylic acids, phthalic acid mono-esters, aromatic keto of ether acids, diphenols such as di(alkylphenol) sulphides and disulphides, sulphonic acids derived from alkyl aryl hydrocarbons or from high boiling petroleum oils, sulphuric acid mono-esters; phosphoric, arsenic and antimonic acid mono- and diesters, including mono- and di-esters of the corresponding thiophosphoric, thio arsenic and thio antimonic acids, phosphonic and arsonic acids.  Examples of these auxiliary detergents are the alkaline earth phosphate and thiophosphate di-esters and the alkaline earth diphenolates, specifically the calcium and barium salts of diphenol mono and polysulphides.  The calcium salts of oil-soluble petroleum sulphonic acid are said to be particularly advantageous.  Other auxiliary additives may include phosphatides such as lecithin, fatty oils such as rape oil, and voltolized fatty or mineral oils.  Anti-rusting compounds such as dicarboxylic acids of 16 or more carbon atoms or organic compounds containing an acidic radical very near to a nitrile, nitro or nitroso group (e.g. alpha cyano stearic acid) and alkali metal salts of sulphonic acids or fatty acids may also be present. Other additives such as blooming agents, pour-point depressants, viscosity improvers, auxiliary anti-oxidants, extreme pressure agents and anti-foaming agents may be present.  Examples of auxiliary anti-oxidants are alkyl phenols such as 2, 4, 6-trimethylphenol, pentamethylphenol, 2, 4-dimethyl-6-tertiary-butylphenol, 2, 4-dimethyl-6-octylphenol, 2, 6-ditertiary-butyl-4-methylphenol, and 2, 4, 6-tritertiary-butylphenol.  The compounded lubricating oil is especially suitable for use in aviation engines.