| abstract |
A lubricating composition, suitable as an internal combustion engine lubricant, a gear lubricant, a turbine oil, an ice machine oil, an instrument lubricant or a base oil for grease manufacture, comprises a major proportion of lubricating oil and a minor proportion of a corrosion inhibitor which consists of one or more m- or p-benzene or hexahydrobenzene dicarboxylic acids or salts or amides thereof. The lubricating oil may be a mineral oil or a synthetic oil, and synthetic hydrocarbon oils mentioned are alkylene polymers, alkyl benzenes (e.g. tetradecyl benzene) and oils derived from coal or shale. Synthetic non-hydrocarbon oils mentioned are alkylene oxide polymers and their ethers and esters, esters of dicarboxylic acids (e.g. di-2-ethylhexyl sebacate, di-n-hexyl fumarate polymer, dibutyl adipate and dilauryl azelate), esters of acids of phosphorus (e.g. tricresyl phosphate and diethyl decanephosphonate), polysiloxanes and organic silicates. The benzene or hexahydrobenzene dicarboxylic acid may carry substituents such as nitro, cyano, sulpho, mercapto, thiocyano, amino, hydroxy, carboalkoxy, alkoxy or alkyl groups and halogen atoms, provided the substituted acids do not form anhydrides. The salts of the acids may be salts of metals or nitrogen bases, such as ammonium, amine or heterocyclic nitrogen base salts. A list of suitable corrosion inhibitors is given. The composition may also contain detergents, dispersants, oxidation inhibitors, sludge inhibitors, pour depressants, viscosity index improvers, antifoaming agents, other rust and corrosion inhibitors, oiliness agents, wear inhibitors and dyes. Suitable metal-containing detergents are metal naphthenates, metal salts of fatty acids and substituted fatty acids (e.g. calcium stearate, normal or basic calcium phenyl stearate, and calcium dichlorostearate), metal salts of aromatic acids and substituted aromatic acids (e.g. normal and basic calcium octyl salicylate), metal petroleum sulphonates, metal salts of alkyl phenols and alkyl phenol sulphides and metal salts of thiophosphoric acid esters. Suitable non-metallic detergents are copolymers in which one monomer is chosen from hexadecene-1, octyl styrene, allyl stearate, lauryl methacrylate, vinyl n-butyl ether or methallyl isobutyl ketone, while the other monomer is chosen from unsaturated mono-and di-carboxylic acids and their amides and esters (e.g. methacrylic acid, N-lauryl acrylamide, pentaerythritol monomethacrylate, maleic acid, N,N-di-tert. butyl monoamide of maleic acid and monopentaerythritol ester of maleic acid). Suitable dispersants are phosphatides and esters of polyhydric alcohols (e.g. pentaerythritol mono-oleate and the glycerol ether of sorbitan mono-laurate) among the examples, mineral lubricating oil compositions are described containing sulphurized basic calcium cetyl phenate, basic calcium petroleum sulphonate and one of the following: iso- or tere-phthalic acid, 5-tert. butyl isophthalic acid, lead isophthalate, dimethyl hexahydro-isophthalic acid, cis- or trans-hexa-hydroterephthalic acid, hexahydro-isophthalic acid (which may be a mixture of cis- and transisomers), diammonium isophthalate, various alkylamine salts of isophthalic, terephthalic, hexahydro - isophthalic and hexahydroterephthalaic acids, isophthalamide and various N-alkyl derivatives thereof. For comparison purposes, similar compositions are described which contain, as the corrosion inhibitor, phthalic acid or anhydride or hexahydrophthalic acid. In further examples, mineral lubricating oil compositions are described containing (i) terephthalic acid, neutral calcium petroleum sulphonate and sulphurized calcium cetyl phenate; or (ii) isophthalic acid and a copolymer of lauryl methacrylate, methacrylic acid and the lauryl ether of polyethylene glycol monomethacrylate, with or without sulphurized di-(paraffin wax alkyl) sulphide. |