GB626251A - Improvements in or relating to mineral lubricating oil compositions - Google Patents

Abstract

Lubricating compositions comprise a mineral lubricating oil, a minor proportion, e.g. 0.1 to 5.0 per cent by weight, of a polyvalent metal salt or salts of an aromatic hydroxy carboxylic acid, and one or more alkyl or alkenyl phenols which are soluble in the lubricating oil and which contain at least one alkyl or alkenyl group of at least eight carbon atoms. The proportion of the substituted phenol present is sufficient to enhance the physical stability of the solution of the salt in the oil and/or the solubility of the salt. The proportion of the phenol present in the composition may be from one tenth to ten times the proportion of the salt. The salt may be a calcium or zinc salt of a branched chain alkyl salicylic acid and the alkyl or alkenyl phenol may be the phenol from which the aromatic hydroxy carboxylate has been derived, [see Group IV (b)]. The alkyl phenol may be para tertiary octyl phenol obtainable by the alkylation of phenol with dimerised isobutene or may be metapentadecenyl phenol. The salts may be derived from mixed alkyl aromatic hydroxy carboxylic acids containing eight to eighteen carbon atoms in the alkyl substituent. The composition may contain, in addition to the oil, salts and phenols, a pour point depressor, a thickener, an oxidation inhibitor, a sludge disperser, an oiliness agent, a viscosity index improver, an anti-corrosion agent and/or an extreme pressure additive. In an example a mineral lubricating oil is mixed with the calcium salts of alkylated salicylic acids containing alkyl substituents of from 8 to 18 carbon atoms (obtained by the alkylation of phenol with cracked wax alkenes and conversion to the salicylic acids) to give a calcium content of 2 per cent by weight of the mixture, which is in the form of a slurry. 10 per cent by weight (based on the quantity of calcium salt present) of commercial p-tertiary octyl phenol (obtained by the alkylation of phenol with dimerised isobutene) is stirred into the slurry at 65 DEG C., giving a clear solution which yields no deposit on prolonged standing. Suitable alkyl and alkenyl phenols are said to include the mineral oil soluble octyl, octenyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, pentadecenyl, hexadecyl and octadecyl phenol. The phenols may be prepared by the di- or tri-alkylation of phenols with alkenes, alkyl halides, alcohols or ethers, or by the mono-alkylation of a cresol, a xylenol, carvacrol or cardanol. Other nuclear substituents, e.g. halogen, alkoxy, alkyl mercapto, p and alkyl amino groups may be present in the phenol, provided they do not increase its water-solubility. The phenols may be cardanol, anacardol, and urushiol in the purified state or as mixtures present in the distillate and distillate residues of oils extracted from the anacardium genus, for example cashew nut oil. The mineral oil forming the major constituent of the lubricating composition may be derived from crude petroleum of any base and may be acid, clay, or solvent refined. The salts of aromatic hydroxy carboxylic acids may be either normal or basic salts or mixtures thereof, and the salt metals may be the alkaline earth metals, aluminium, beryllium, cobalt, nickel, zinc and tin. The acid radicals of the salts may be derived from octyl, nonyl, decyl, dodecyl, tetradecyl, pentadecenyl or hexadecyl salicylic acid, from octyl or decyl parahydroxy benzoic acids, or from alkyl substituted naphthoic acids. The classes of other additives which may be used in conjunction with the salts and phenols of the invention include olefin polymers, metal or amine soaps of fatty acids, naphthenic acids or naphthasulphonic acids, organic phosphates, phosphites, thiophosphites or thiophosphates, metal phenate or alcoholates, metal salts of the condensation products of alkyl phenols and formaldehyde, or of alkyl phenol sulphides, sulphurised mineral or fatty oils, sulphurised olefines, sulphurised unsaturated carboxylic acids, high molecular weight polycarboxylic acids such as are obtained by the condensation of long chain alkenes with maleic anhydride, reaction products of aliphatic acids with phosphorus pentasulphide, halogen-containing compounds such as chlorinated paraffin wax and dichlorostearates, alicyclic alcohols or esters, and organo - silicon compounds. Specifications 536,827 and 586,461 are referred to.ALSO:Mixtures of polyvalent metal salts of aromatic hydroxy carboxylic acids and oil soluble alkyl or alkenyl phenols in which the alkyl or alkenyl groups contain at least eight carbon atoms are prepared by alkylating phenol and partially converting the alkyl phenols so formed into salts of hydroxy carboxylic acids. In the example a mixture of alkyl salicylic acids is made by alkylating phenol with a mixture of alkenes containing 8 to 18 carbon atoms in the molecule and converting the alkyl phenols so formed into the alkyl salicylic acids, about 25 per cent by weight of the alkyl phenols being left unconverted. The alkyl salicylic acids are then converted into their calcium or zinc salts. The mixtures of salts and phenols may be used as additives in lubricating oils (see Group III). Specifications 536,827 [Group III], and 586,461 are referred to.