Patent GB-790472-A (GB)
Title: Lubricating oil compositions
Inventor: GOLOTHAN DAVID WILLIAM
Filed: 1955-01-27
Abstract: A lubricating oil composition particularly for use in protecting internal combustion engines against rusting comprises a major proportion of a lubricating oil, a minor proportion of an oil-soluble salt of an aromatic carboxylic acid, and a minor proportion of a partial ester of a tetrahydric, pentahydric or hexahydric alcohol. The lubricating oil which comprises 80-97.5 per cent of the composition may be a mineral oil derived from naphthenic, paraffinic or asphaltic crudes, or a synthetic oil such as those prepared by the polymerization of olefins or the alkylation of aromatic hydrocarbons with olefins or alkyl halides in the presence of a Friedel-Crafts catalyst, di(2-ethyl-hexyl) sebacate or adipate, and the alkyl or alkaryl esters of inorganic esters such as trioctyl or tricresyl phosphate and tetraoctyl silicate, polymers or copolymers of polyalkylene glycols and the esters and ethers thereof, and polyorganosiloxanes.  The salts of aromatic carboxylic acids may be the sodium, potassium, calcium, barium, strontium, magnesium, aluminium, zinc, lead, tin, iron, nickel or amine salts of aromatic acids containing alkyl, alkenyl, cycloalkyl or aryl radicals, hydroxy, alkoxy, aroxy and amino groups and halogen atoms.  Typical acids are methylbenzoic acid, butylbenzoic acid, dibutylbenzoic acid, chloro- and bromobenzoic acids, and alkylated salicylic, e.g. the di-isopropyl and octyl acids and especially the normal or basic salts described in Specification 586,461, viz those of aluminium, beryllium, barium, calcium, magnesium, lithium, cobalt, nickel, zinc strontium or tin of octadecyl or stearyl salicylic acid.  Highly basic salts may be prepared by the processes of Specifications 729,376, 759,344, 759,346, 786,167 and 790,471.  The partial esters may be prepared from diglycerol, erythritol, pentacrythritol, methylerythritol, sorbitan, arabitol, xylitol, adonitol, rhamnitol, mannitan, manitol sorbitol, dulcitol and polyoxyalkylene derivatives of these alcohols with an aid having 6-30 carbon atoms in the molecule such as caproic, caprylic, lauric, palmitic, stearic, oleic, linoleic, ricinoleic, erucic, behenic and arachidic acids; naphthenic acids, tall oil acids, or from aromatic acids such as benzoic, salicylic, or naphthoic acids or from dicarboxylic acids such as citric acid.  Also fatty acid mixtures obtained from castor oil, olive oil, linseed oil, rapeseed oil or coconut oil may be used. Specific esters are sorbitol mono-oleate, sorbitan mono-oleate monolaurate, monopalmitate, monostearate and trioleate, mannitan monooleate and monopalmitate polyoxyethylenesorbitol mono-oleate, the monoester of cotton-seed fatty acids and polyoxyethylenesorbitol, polyoxyethylenemannitan monopalmitate, pentaerythritol monostearate monocaprate, monolaurate and mono-oleate and the mono-oleate, monolaurate, monopalmitate and monostearate of poly oxyethylenesorbitan.  In addition, an oil-soluble alkali metal salt of an organic sulphonic acid may be incorporated such as the sodium, or potassium, or the calcium, barium, zinc or amine salts of oil-soluble petroleum sulphonic acids, and tri-isopropyl naphthalene sulphonic acid.  Antioxidants and anti-corrosion agents such as 2,4 - dimethyl - 6 - tertiary butyl phenol; 2,4,6-trimethylphenol; 2,4-dimethyl - 6 - tertiary - octylphenol; 2,6 - dibutyl - 4 - methyl phenol; 2,4 - dimethyl - 6-tertiary butyl thiophenol; 2,21-methylene-bis (4 - methyl - 6 - tertiary butylphenol); 2,21-methylene bis (4,5 - ditertiarybutyl phenol); phenyl alpha naphthylamine; phenyl beta naphthylamine; N,N1 - dibutyl para phenylene diamine; N,N,N1,N1 - tetramethyldiaminodiphenylmethane, mercaptobenzthiazole, alpha cyano stearic acid, dicyclohexylamine, N - phenylmorpholine, octadecylamine, amines prepared from paraffin wax and the amines from coconut oil acids may be added.  A typical example is SAE 20 mineral lubricating oil 94.5 parts, sorbitol mono-oleate 5.0 parts and calcium alkyl salicylates containing 14-18 carbon atoms in the alkyl groups 0.5 parts.