Patent GB-600325-A (GB)
Title: An improved fluid lubricant
IPC: C09D5/08
Filed: 1945-06-11
Abstract: A lubricating oil for delicate mechanisms such as those employed in watches, clocks, scientific instruments and ordnance equipment, comprises an ester of the general formula <FORM:0600325/III/1> where R1 and R2 are C4 or higher branched chain alkyl, aralkyl in which the alkyl part is branched chain, or cyclo-alkyl radicles, and R is a bivalent aliphatic hydrocarbon radicle, together with from 0.01 to 1 per cent by weight of an antioxidant of the amine or phenolic type. The ester may be an ester of malonic, succinic, isosuccinic, glutaric, ethyl malonic, pyrotartaric, adipic, pimelic, suberic or azelaic acid or mixtures of such acids or a synthetic acid produced by dimerisation or polymerization of unsaturated fatty acids or their esters. Secondary butyl, cyclohexyl and secondary octyl phenyl are representative of radicles R1 and R2, and specific esters mentioned are di - sec. - butyl sebacate, di - 2 - ethylhexyl sebacate, di-2-ethylhexyl succinate and di-2-ethyl hexylazelate.  Suitable antioxidants are alpha or beta naphthol, 2,6-ditertiary butyl para cresol, catechol, guaiacol, tertiary butyl phenol, tertiary butyl phenol sulphide and phenyl alpha naphthylamine.  The lubricating oil may also contain anti-creep agents, dyes, organic bases, onium compounds, foam suppressors such as silicones, aliphatic or cyclic amines, alkanolamines, pour depressants or phenol sulphide metal phenates.  Suitable anti-creep agents are soaps such as the stearate, naphthenate, or mahogany sulphonate of a bivalent metal such as zinc, tin, calcium, or barium or highly polar dibasic organic acids such as alkyl succinic, alkylated phthalic or alkyl thiosuccinic acid, or lithium, sodium or octadecenyl amine mahogany sulphonates.  In examples, lubricating oil compositions comprise: (1) di-2-ethyl hexyl sebacate, 2,6-di-tertiary butyl-4-methyl phenol and undecyl succinic acid or calcium petroleum sulphonate, and (2) an ester of sebacic acid in which the esterifying radicles are branched chain C4-C20 alkyl radicles, metal soap, metal mahogany sulphonate and antioxidant.  For comparison purposes compositions are referred to which comprise di-2-ethyl hexyl sebacate with calcium mahogany sulphonate or zinc naphthenate.ALSO:A lubricating oil for delicate mechanisms comprises an ester of the general formula <FORM:0600325/IV(b)/1> where R1 and R2 are C4 or higher branched chain alkyl, aralkyl in which the alkyl part is branched chain, or cycloalkyl radicles, and R is a bivalent aliphatic hydrocarbon radicle, together with from 0.01 to 1 per cent by weight of an antioxidant of the amine or phenolic type.  The ester may be an ester of malonic, succinic, isosuccinic, glutaric, ethyl malonic, pyrotartaric, adipic, pimelic, suberic or azelaic acid, or mixtures of such acids or a synthetic acid produced by dimerization or polymerization of unsaturated fatty acids or their esters.  Secondary butyl, cyclohexyl and secondary octylphenyl are representative of radicles R1 and R2 and specific esters mentioned are di-sec. butyl sebacate, di-2-ethylhexyl sebacate, di-2-ethyl hexyl succinate and di-2-ethyl hexyl azelate.  The esters may be prepared by reacting the alcohol with the acid at elevated temperatures in the presence of an esterification catalyst such as sulphuric acid or sulphosalicylic acid.  The reaction is facilitated by a continuous removal of water by azeotropic distillation with a solvent such as benzene or toluene, or by passing an inert gas through the reaction mixture.  The product may be washed with alkali, heated under reduced pressure with or without blowing with an inert gas, clay treated and finally blotter pressed.