Patent GB-844778-A (GB)
Title: Improvements relating to synthetic lubricants
Filed: 1957-05-24
Abstract: A lubricating composition comprises a blend of a liquid aliphatic diester of a saturated aliphatic dicarboxylic acid, or a mixture of such diesters, and a polyester, soluble in the diester, and having the general formula ROOCR1COO (R2OOCR1COO)nR where n is an integer, the Rs are hydrocarbon residues of monohydric alcohols ROH, the R1s are hydrocarbon residues of dicarboxylic acids HOOCR1COOH and R2s are residues of diols HOR2OH, or a mixture of such polyesters, the polyester or polyester mixture having been prepared by reacting in one or more stages (a) an acid or acids of the formula HOOCR1COOH, or the anhydrides of such acids (where they exist), where R1 is an alkylene group having 4-14 carbon atoms, (b) a saturated monohydric alcohol or alcohols of the formula ROH where R is an alkyl group having 4-18 carbon atoms, (c) a diol or diols of the formula HOCH2C(R6)(R7)CH2OH where R6 is a methyl or ethyl group and R7 is an alkyl group having 1-4 carbon atoms, and (d)1,3-butanediol, the total molecular proportion of (c) and (d) being at least half the molecular proportion of (b), and the total molecular proportion of (b), (c) and (d) being greater than the molecular proportion of (a), the relative proportions of diester and polyester in the blend being such that the viscosity of the blend at 210,F. is 4-30 centistokes.  The diesters may have the formula R4OOCR5COOR4 where R5 is an alkylene group having 4-14 carbon atoms and the R4s are alkyl groups, preferably branched-chain, having 4-18 carbon atoms.  The lubricating composition may also contain an antioxidant, such as phenothiazine, or a crystallization suppressant, such as a polymerized alkyl ester of acrylic of methacrylic acid.  In the examples, lubricating compositions are described consisting of a diester (a blend of octyl nonyl sebacate, dioctyl sebacate and dinonyl sebacate prepared from sebacic acid, 2-ethylhexanol and 3, 5, 5-trimethylhexanol), a polyester (prepared from sebacic acid, 2-ethyl hexanol, 2, 2-dimethyl-1, 3-propanediol and 1, 3-butanediol) and phenothiazine. For comparison purposes, a similar lubricating composition is described wherein the polyester is prepared from sebacic acid, 2-ethylhexanol and 1, 2-propanediol.  Lubricating compositions are also described consisting of dioctyl or dinonyl sebacate and a polyester prepared from sebacic acid, 2-ethylhexanol and polyglycol 200.  According to the Provisional Specification, the dicarboxylic acid HOOCR1COOH employed in the preparation of the polyester may be an aromatic acid such as phthalic acid and there is mentioned, for comparison purposes, a polyester derived from sebacic acid, phthalic anhydride, 2-ethylhexanol and propylene glycol.ALSO:A polyester, which is employed as an ingredient of a lubricating composition (see Group III) has the general formula ROOCR1COO (R2OOCR1COO)nR where n is an integer, the Rs are hydrocarbon residues of monohydric alcohols ROH, the R1s are hydrocarbon residues of dicarboxylic acids HOOCR1COOH and the R2s are residues of diols HOR2OH.  The polyester, or a mixture of such polyesters, is prepared by reacting in one or more stages (a) an acid or acids of the formula HOOCR1-COOH, or the anhydrides of such acids (where they exist), where R1 is an alkylene group having 4-14 carbon atoms, (b) a saturated monohydric alcohol or alcohols of the formula ROH, where R is an alkyl group having 4-18 carbon atoms, (c) a diol or diols of the formula HOCH2C(R6)R7)CH2OH where R6 is a methyl or ethyl group and R7 is an alkyl group having 1-4 carbon atoms and (d) 1,3- butanediol, the total molecular proportion of (c) and (d) being at least half the molecular proportion of (b), and the total molecular proportion of (b), (c) and (d) being greater than the molecular proportion of (a).  In an example, the polyester is prepared from sebacic acid, 2-ethylhexanol, 2,2-dimethyl-1,3-propanediol and 1,3-butanediol. For comparison purposes, the preparation of a polyester from sebacic acid, 2-ethylhexanol and 1,2-propanediol is described. According to the Provisional Specification, the dicarboxylic acid HOOCR1COOH employed in the preparation of the polyester may be an aromatic acid such as phthalic acid and there is mentioned, for comparison purposes, a polyester derived from sebacic acid, phthalic anhydride, 2-ethylhexanol and propylene glycol.ALSO:A lubricating composition, suitable for the lubrication of aero gas turbine engines, comprises a blend of a liquid aliphatic diester of a saturated aliphatic dicarboxylic acid, or a mixture of such diesters, and a polyester, soluble in the diester, and having the general formula ROOCR1COO(R2OOCR1COO)nR where n is an integer, the Rs are hydrocarbon residues of monohydric alcohols ROH, the R1s are hydrocarbon residues of dicarboxylic acids HOOCR1COOH and the R2s are residues of diols HOR2OH, or a mixture of such polyesters, the polyester or polyester mixture having been prepared by reacting in one or more stages (a) an acid or acids of the formula HOOCR1COOH, or the anhydrides of such acids (where they exist), where R1 is an alkylene group having 4-14 carbon atoms, (b) a saturated monohydric alcohol or alcohols of the formula ROH, where R is an alkyl group having 4-18 carbon atoms, (c) a diol or diols of the formula HOCH2C(R6)(R7)CH2OH where R6 is a methyl or ethyl group and R7 is an alkyl group having 1-4 carbon atoms, and (d) 1,3-butanediol, the total molecular proportion of (c) and (d) being at least half the molecular proportion of (b), and the total molecular proportion of (b), (c) and (d) being greater than the molecular proportion of (a), the relative proportions of diester and polyester in the blend being such that the viscosity of the blend at 210 DEG F. is 4-30 centistokes.  The diesters may have the formula R4OOCR5COOR4 where R5 is an alkylene group having 4-14 carbon atoms and the R4s are alkyl groups, preferably branched-chain, having 4-18 carbon atoms.  The lubricating composition may also contain an anti-oxidant, such as phenothiazine, or a crystallization suppressant, such as a polymerized alkyl ester of acrylic or methacrylic acid.  In the examples, lubricating compositions are described consisting of a diester (a blend of octyl nonyl sebacate, dioctyl sebacate and dinonyl sebacate prepared from sebacic acid, 2-ethylhexanol and 3,5,5-trimethylhexanol), a polyester (prepared from sebacic acid, 2-ethylhexanol, 2,2-dimethyl-1,3-propanediol and 1,3-butanediol) and phenothiazine.  For comparison purposes, a similar lubricating composition is described wherein the polyester is prepared from sebacic acid, 2-ethylhexanol and 1,2-propanediol. Lubricating compositions are also described consisting of dioctyl or dinonyl sebacate and a polyester prepared from sebacic acid, 2-ethylhexanol and polyglycol 200.  According to the Provisional Specification, the dicarboxylic acid HOOCR1COOH employed in the preparation of the polyester may be an aromatic acid such as phthalic acid and there is mentioned, for comparison purposes, a polyester derived from sebacic acid, phthalic anhydride, 2-ethylhexanol and propylene glycol.