Patent GB-811650-A (GB)
Title: Process for preparing lubricant compositions and concentrates therefor
Filed: 1956-05-07
Abstract: Concentrates of phthalic acid and hexahydrophthalic acid additives in lubricating oil are prepared by a process which comprises reacting a phthalic acid with a tertiary amine, combining the product with the lubricating oil, and then separating off the amine component.  The reaction may be carried out in a volatile solvent, e.g. benzene. Applicable lubricating oils are any of the well known hydrocarbon mineral oils, e.g. naphthenic, paraffinic or mixed naphthenic and paraffinic oils, or synthetic oils such as synthetic hydrocarbon oils, e.g. alkylene polymers and coal and shale derivatives; diesters, e.g. di-2-ethylhexyl sebacate, and di-n-hexyl fumarate polymer; alkyl benzenes, e.g. tetradecyl benzene; liquid esters of phosphorus acids, e.g. tricresyl phosphate and diethyl esters of decane phosphonic acid; polysiloxane oils, e.g. polyalkyl-, polyaryl-, polyalkoxy-, and polyaryloxy-siloxanes and silicate ester oils, e.g. tetra-alkyl and tetraaryl silicates.  Suitable phthalic acids include phthalic, isophthalic and terephthalic acids and their nuclear substituted analogues, e.g. 5-tertiary butyl is ophthalic acid, hexahydrometaphthalic acid and hexahydroparaphthalic acid.  The amines have the formula N.R1.R2.R3 where R1, R2, and R3 may be the same or different aliphatic, aryl, aryl aliphatic or hydroxy aliphatic groups or of which two or all three may be combined as in the case of cycloaliphatic or heterocyclic tertiary amines, examples being trimethylamine, triethylamine, dimethylethylamine, N,N - dimethyl - N - benzylamine, N,N - dimethylaniline, N - methyl piperidine, pyridine, and triethanolamine.  Optional additives which may be included are detergents, e.g. metal salts of naphthenic acids, fatty acids and substituted fatty acids, aromatic and substituted aromatic acids, petroleum sulphonic acids, alkyl phenol sulphides, alkyl phenols, thiophosphoric acid esters and wax substituted phenol derivatives, and macromolecular polymers such as copolymers of methacrylic acid and lauryl methacrylate; dispersants, e.g. phosphatides, and esters of long chain carboxylic acids and polyhydric alcohols such as pentaerythritol mono-oleate and other conventional additives. In an example terephthalic acid is reacted with pyridine in benzene solution, mixed with a mineral oil containing calcium petroleum sulphonate and sulphurized calcium alkyl phenate, and the pyridine and benzene then stripped off under vacuum. It is stated that stable dispersion up to a concentration of at least 5 per cent by weight of phthalic acids in lubricating oil may thus be obtained.  Specification 809,198 is referred to.ALSO:Amine salts of phthalic acids are obtained by reacting the acids with a tertiary amine, preferably in an excess of the amine or, alternatively in the presence of an inert solvent such as benzene or toluene.  The tertiary amine may be any basic tertiary amine capable of forming a thermally unstable salt with the phthalic acid and preferably boils below 600 DEG  F.  Amines mentioned are those of the general formula NR1R2R3 where R1,R2 and R3 may be the same or different aliphatic, aryl aliphatic, aryl or hydroxyaliphatic group and two or more may be combined to form a single group as in the case of cycloaliphatic and heterocyclic tertiary amines, examples being trimethylamine, triethylamine, dimethylethylamine, N,N-dimethyl-N-benzylamine, N,N-dimethylaniline, N-methyl piperidine, pyridine, and triethanolamine.  Phthalic acids mentioned are phthalic acid, isophthalic acid, terephthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid and their nuclear substituted analogues such as 5-t-butyl isophthalic acid. An example describes the preparation of the pyridine salt of terephthalic acid.  Dispersions of the above salts in lubricating oils yield the corresponding amine on heating.  Specification 809,198, [Group III], is referred to.