GB814572A - Improvements in and relating to lubricating compositions - Google Patents

Abstract

Lubricating oil compositions with good viscosity-temperature characteristics comprise a major proportion of a mineral lubricating oil, a minor proportion of a polymer or copolymer of one or more esters of the general formula <FORM:0814572/III/1> where Y is <FORM:0814572/III/2> or <FORM:0814572/III/3> X is H or a hydrocarbon group and R is a monovalent hydrocarbon radical, preferably a C8-20 radical, or a copolymer of such an ester with a polymerizable heterocyclic nitrogen base compound and a minor proportion of an organic fluorine-containing compound either in addition to or as part of the polymer. The base oils may be derived from paraffinic, naphthenic, asphaltic or mixed base crude petroleum stocks. Examples of copolymers include those of octyl and lauryl methacrylates; vinyl stearate and laurate; 2-methyl-5-vinyl pyridine and lauryl or octadecyl methacrylate; N-vinyl pyrrolidone and lauryl or octadecyl methacrylate; and terpolymers such as 2-methyl-5-vinyl pyridine with lauryl and octadecyl methacrylates. Many examples of organic fluorine-containing compounds are given including fluorinated C5.50 aliphatic, cycloaliphatic and aromatic hydrocarbons, amines, ethers, acids, alcohols, esters and amides. The fluorinated compound or mixture thereof may comprise 0.01 to 10 per cent wt. of the whole composition. The fluorine compound may be a monomeric unit of the copolymer, in which case it may account for between 1 and 5 per cent of the molecular weight of the polymer. Suitable fluorine-containing monomers are trifluorovinyl chloride, trifluoromethyl acrylonitrile, vinyl trifluoro acetate and perfluorobutyl acrylate which may be copolymerized with vinyl pyridines or pyrrolidones and methacrylates. The molecular weights of the polymers may be: for ester polymers and copolymers over 104 and preferably below 106; for ester/nitrogen compound copolymers 7.5 X 103 to 2.5 X 106; and for ester/nitrogen compound/fluoro compound copolymers 1.5 X 103 to 2 X 106. They may constitute between 0.1 and 10 wt. per cent of the total composition. Optional ingredients mentioned are corrosion inhibitors, e.g. sodium, lithium and diisopropyl ammonium nitrites, and polyvalent metal thiophosphates, e.g. calcium or zinc dicyclohexyl thiophosphate or methylcyclohexyl thiophosphate; E.P. agents such as organic phosphites, phosphates and phosphonates, e.g. trichloroethyl phosphite and tricresyl phosphate; P2S5-terpene reaction products; organic sulphides, e.g. wax disulphide or ethylene bistolyl sulphide; anti-oxidants such as amines and phenols, e.g. octadecyl amine, phenyl a -naphthylamine or 2,6-di-t-butyl-4-methyl phenol; and other additives such as metal phenates and sulphonates, e.g. Ca or Ba salt of octyl phenol-formaldehyde condensation product or neutral or basic Ca or Ba petroleum sulphonate. Examples comprise (i) a mineral lubricating oil; (ii) one of the following copolymers: lauryl methacrylate/N-vinyl pyrrolidone, lauryl methacrylate/octyl methacrylate, or octadecyl methacrylate/2-methyl-5-vinyl pyridine; and (iii) one of the following: fluorobenzene, perfluoromethyl cyclohexane, 4-fluorobiphenyl; a fluorinated cyclic ether (C8F16O), heptacosofluorotributylamine, diiodopentane, diiodobenzene, 1,4-dichlorobutane, chlorowax, or glycerol monooleate, the last five being included for purposes of comparison. Specifications 583,874, [Group IV], 634,673, [Group IV (a)], and 752,383 are referred to.ALSO:Fluorine-containing copolymers are added to lubricating oils (see Group III). The copolymers are those obtained by copolymerising an ester of the general formula <FORM:0814572/IV (a)/1> where X represents an hydrogen atom or hydrocarbon group and Y represents <FORM:0814572/IV (a)/2> or <FORM:0814572/IV (a)/3> with another such ester and/or a polymerisable heterocyclic nitrogen compound at least one of which contains at least one substituent fluorine atom. Examples of fluorine-containing monomers are trifluorovinyl chloride, trifluoromethylacrylonitrile, vinyl trifluoroacetate and perfluorobutyl acrylate. They may be copolymerized with vinyl pyridines or alkyl methacrylates, vinyl pyrrolidones, vinyl esters, or mixtures. The preferred terpolymers have molecular weights of 1.5 X 103 to 2 X 106 with the fluorine-containing monomer unit accounting for less than 10 per cent of the total molecular weight. Specific examples of such copolymers are vinyl pyridine/lauryl methacrylate/vinyl trifluoro acetate; 2-methyl-5-vinyl pyridine/octadecyl methacrylate/trifluorovinyl chloride; N-vinyl pyrrolidone/octadecyl methacrylate/trifluorovinyl chloride; and trifluoromethyl acrylonitrile/vinyl stearate. Specifications 583,874, [Group IV], 634,673 and 752,383, [Group III], are referred to.