Patent GB-837978-A (GB)
Title: Improvements relating to synthetic lubricants
Filed: 1957-01-01
Abstract: A lubricating composition, especially suitable for use in aero gas turbines, comprises a blend of (i) a liquid aliphatic diester of a saturated aliphatic dicarboxylic acid, and (ii) a polyester of the formula ROOCR1COO(R2OOCR1COO)nR where n is an integer, R is the hydrocarbon residue of an aliphatic monohydric alcohol ROH, R1 is the hydrocarbon residue of an aromatic or aliphatic dicarboxylic acid HOOCR1COOH and R2 is the residue of 1,3-butylene glycol, i.e. -CH2CH2CH(CH3)-, the relative proportions of diester and polyester in the blend being such that the viscosity of the blend at 210 DEG  F. lies between 2 and 30 centistokes.  Ingredient (i) may be a diester of the formula R4OOCR5 COOR4, where R5 is a C4-C14 alkylene group and R4 is a C4-C18 alkyl group, specific examples being dioctyl sebacate, dinonyl sebacate and octyl nonyl sebacate.  Monohydric alcohol ROH of ingredient (ii) may be 2-ethylhexyl, 2-ethylbutyl, cetyl, neopentyl or trimethylnonyl alcohol, while dicarboxylic acid HOOCR1COOH may be sebacic, phthalic, adipic, azelaic, brassylic, suberic, pimelic, glutaric or succinic acid.  These acids may be employed in the form of their anhydrides, where they exist.  The lubricating composition may also contain an antioxidant (e.g. phenothiazine) or a crystallization suppressant (e.g. a polymer of an alkyl ester of acrylic or methacrylic acid). In the examples, the polyesters are prepared from 2-ethyl hexanol, 1,3-butyleneglycol and sebacic acid, with or without phthalic anhydride, and are blended with octyl nonyl sebacate and phenothiazine.  For comparison purposes, similar lubricating compositions are described in which the polyester is prepared with the use of 1,2-propylene glycol or tetraethylene glycol instead of 1,3-butylene glycol.ALSO:An ingredient of a lubricating composition (see Group III) is a polyester of the formula ROOCR1COO(R2OOCR1COO)nR, where n is an integer, R is the hydrocarbon residue of an aliphatic monohydric alcohol ROH, R1 is the hydrocarbon residue of an aromatic or aliphatic dicarboxylic acid HOOCR1COOH, and R2 is the residue of 1,3-butylene glycol, i.e. -CH2CH2-CH(CH3)-. Monohydric alcohol ROH may be 2-ethylhexyl, 2-ethylbutyl, cetyl, neopentyl or trimethylnonyl alcohol, while dicarboxylic acid HOOCR1COOH may be sebacic, phthalic, adipic, azelaic, brassylic, suberic, pimelic, glutaric or succinic acid.  The polyesters may be prepared by reacting, in one or more stages, the dicarboxylic acid or acids (or the corresponding anhydrides where they exist), the monohydric alcohol and 1,3-butylene glycol.  In the examples, polyesters are prepared by reacting together sebacic acid (with or without phthalic anhydride), 2-ethyl hexanol and 1,3-butylene glycol. For comparison purposes, the preparation is described of polyesters from (a) sebacic acid, 2-ethyl hexanol and polyglycol 200 (essentially tetraethylene glycol) and (b) sebacic acid (with or without phthalic anhydride), 2-ethyl hexanol and 1,2-propylene glycol.ALSO:An ingredient of a lubricating composition (see Group III) is a polyester of the formula ROOCR1COO(R2OOCR1COO)nR, where n is an integer, R is the hydrocarbon residue of an aliphatic monohydric alcohol ROH, R1 is the hydrocarbon residue of an aromatic or aliphatic dicarboxylic acid HOOCR1COOH, and R2 is the residue of 1,3-butylene glycol, i.e. -CH2CH2CH(CH3)-.  Monohydric alcohol ROH may be 2-ethylhexyl, 2-ethylbutyl, cetyl, neopentyl or trimethylnonyl alcohol, while dicarboxylic acid HOOCR1COOH may be sebacic, phthalic, adipic, azelaic, brassylic, suberic, pimelic, glutaric or succinic acid.  The polyesters may be prepared by reacting, in one or more stages, the dicarboxylic acid or acids (or the corresponding anhydrides where they exist), the monohydric alcohol and 1,3-butylene glycol.  In the examples, polyesters are prepared by reacting together sebacic acid (with or without phthalic anhydride), 2-ethyl hexanol and 1,3-butylene glycol.  For comparison purposes, the preparation is described of polyesters from (a) sebacic acid, 2-ethyl hexanol and polyglycol 200 (essentially tetraethylene glycol, and (b) sebacic acid (with or without phthalic anhydride), 2-ethyl hexanol and 1,2-propylene glycol.