A lubricating composition comprises (1) a liquid ester of the formula R1OOCRCOOR11, wherein R is a divalent saturated aliphatic hydrocarbon radical and R1 and R11 are alkyl, aralkyl or cycloalkyl radicals of more than two carbon atoms; (2) from 2 to 30 per cent., preferably 5 to 15 per cent., based on the combined weight of ester and polymer, of a polymer of an ester of acrylic acid or a 1-alkacrylic acid and (3) a Group II metal salt of an aromatic carboxylic acid or phenol in such amount that the metal content of the composition is from 0.01 to 1.0 per cent. Suitable polymers or copolymers are derived from methyl, ethyl, n-propyl, isopropyl, isobutyl, lauryl, phenyl or benzyl esters of acrylic, methacrylic, 1-ethyl acrylic and 1-propyl acrylic acids. The polymers preferably have a relative molecular weight between 100 and 180 centistokes and may be subjected to a shearing action prior to incorporation in the composition. Typical esters are di(2-methylheptyl) adipate, di (3.5.5-trimethylhexyl) adipate or sebacate, di (3-ethylhexyl) adipate or sebacate, dihexylpimelate, di (2-ethylhexyl) sebacate, di-sec. butyl sebacate or malonate, di (1-ethylpropyl) azelate and dibutyl ethylmalonate. The metallic salt may be normal or basic and is preferably a zinc or calcium salt of benzoic, naphthoic, 4-t-butyl benzoic, 2.4-di-t-butyl-benzoic, di-isopropylsalicylic, octylsalicylic, pentadecenylsalicylic, octadecylsalicylic, stearyl-salicylic or octyl 4-hydroxybenzoic acid or of phenol, naphthol, cresol, alkylated phenols and di or tri alkylated phenols. Nuclear substituents such as halogen, alkoxy, alkyl mercapto and alkyl amino may be present in the phenol and particularly effective salts are the condensation products of substituted phenols and formaldehyde, acetaldehyde or paraformaldehyde. The composition may also contain mineral lubricating oils, extreme pressure additives such as trioctyl and tricresyl phosphates, monobutyl trichloromethanephosphonate or its di (2-ethylhexyl) amine salt, antioxidants such as alkylated phenols and diphenols and condensation products of ethylene or propylene oxide with sebacic acid and ethers or esters of these condensates. In examples the physical properties of compositions containing polymethyl acrylate or methacrylate are given.ALSO:Lubricants for use in aircraft and gas turbines comprise a saturated ester R1OOCRCOOR11, wherein R is a divalent saturated aliphatic hydrocarbon radical and R1 and R11 are alkyl, aralkyl or cycloalkyl radicals of more than two carbon atoms, from 2 to 30 per cent., based on the combined weight of polymer and ester, of a polymer of an ester of acrylic acid or a 1-alkacrylic acid and a Group II metal salt of an aromatic carboxylic acid or phenol in such amount that the metal content of the composition is from 0.01 to 1.0 per cent. Suitable polymers or copolymers are derived from methyl, ethyl, n-propyl, isopropyl, isobutyl, lauryl, phenyl or benzyl esters of acrylic, methacrylic, 1 - ethylacrylic and 1 - propylacrylic acids. The polymers preferably have a relative molecular weight between 100 and 180 centistokes and may be subjected to a shearing action prior to incorporation in the composition. Typical esters are di (2-methylheptyl) adipate, di (3.5.5-trimethylhexyl) adipate or sebacate, di (3-ethylhexyl) adipate or sebacate, dihexylpimelate, di (2-ethylhexyl) sebacate, di-sec. butyl sebacate or malonate, di (1-ethylpropyl) azelate and dibutyl ethylmalonate. The metallic salt may be normal or basic and is preferably a zinc or calcium salt of benzoic, naphthoic, 4 - t - butylbenzoic, 2.4 - di - t - butylbenzoic, di-isopropylsalicylic, octylsalicylic, pentadecenylsalicylic, octadecylsalicylic, stearylsalicylic or octyl-4-hydroxy-benzoic acid or of phenol, naphthol, cresol, alkylated phenols and di or tri alkylated phenols. Nuclear substitutes such as halogen, alkoxy, alkyl mercapto and alkyl amino may be present in the phenol and particularly effective salts are the condensation products of substituted phenols and formaldehyde, acetaldehyde or paraformaldehyde. The composition may also contain mineral lubricating oils, extreme pressure additives such as trioctyl and tricresyl phosphates, monobutyl trichloromethane-phosphonate or its di (2-ethylhexyl) amine salt, antioxidants such as alkylated phenols and diphenols and condensation products of ethylene or propylene oxide with sebacic acid and ethers or esters of these condensates. In examples the physical properties of compositions containing polymethyl acrylate or methacrylate are given.
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