GB844779A - Improvements relating to synthetic lubricants - Google Patents

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 HO(R2OOCR1COO)nCH2OH where n is an integer, 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 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 (c) 1,3-butanediol, the total molecular proportion of (b) and (c) being greater than the molecular proportion of (a), and 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 diester preferably has the formula R4OOCR5COOR4 where p R5 is an alkylene group having 4-14 carbon atoms and the R4s are alkyl groups, especially branched-chain, having 4-18 carbon atoms. Examples of suitable diesters are (i) di (2-ethylhexyl) sebacate, (ii) di (3, 5, 5-trimethylhexyl) sebacate, (iii) 2-ethylhexyl (3, 5, 5, trimethyl hexyl) sebacate and mixtures of (i), (ii) and (iii). The lubricating composition may contain an antioxidant such as phenothiazine. In an example, a lubricating composition is described consisting of diester (a blend of octylnonyl sebacate, dioctyl sebacate and dinonyl sebacate, prepared by reacting together sebacic acid, 2-ethylexanol and 3, 5, 5-trimethylhexanol), polyester (prepared by reacting together sebacic acid, 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 poly (propylene glycol sebacate). Specification 763,077 is referred to.ALSO:A polyester, which is employed as an ingredient of a lubricating composition (see Group III) has the general formula HO(R2OOCR1COO)nCR2OH where n is an integer, 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 HOOCR1COOH, or the anhydrides of such acids (where they exist), where R1 is an alkylene group having 4-14 carbon atoms, (b) 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 (c) 1,3-butanediol, the total molecular proportion of (b) and (c) being greater than the molecular proportion of (a). In an example, the polyester is prepared by reacting together sebacic acid, 2,2-dimethyl-1,3-propanediol and 1,3-butanediol. A diester is prepared by reacting equimolar amounts of sebacic acid, 2-ethyl-hexanol and 3:5:5-trimethyl hexanol. Specification 763,077 is referred to.ALSO:A lubricating composition, suitable for the lubrication of aero gas turbines, comprises a blend of a liquid aliphatic diester of a saturated aliphatic dicarboxylic acid, of a mixture of such diesters, and a polyester, soluble in the diester, and having the general formula HO(R2OOCR1COO)nCH2OH where n is an integer, 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, of the anhydrides of such acids (where they exist), where R1 is an alkylene group having 4-14 carbon atoms, (b) 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 (c) 1,3-butanediol, the total molecular proportion of (b) and (c) being greater than the molecular proportion of (a), and 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 diester preferably has the formula R4OOCR5COOR4 where R5 is an alkylene group having 4-14 carbon atoms and the R4s are alkyl groups, especially branched-chain, having 4-18 carbon atoms. Examples of suitable diesters are (i) di (2-ethylhexyl) sebacate, (ii) di (3,5,5-trimethylhexyl) sebacate, (iii) 2-ethylhexyl (3,5,5-trimethylhexyl) sebacate and mixtures of (i), (ii) and (iii). The lubricating composition may contain an antioxidant such as phenothiazine. In an example, a lubricating composition is described consisting of diester (a blend of octyl nonyl sebacate, dioctyl sebacate and dinonyl sebacate, prepared by reacting together sebacic acid, 2-ethylhexanol and 3,5,5-trimethylhexanol), polyester (prepared by reacting together sebacic acid, 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 poly (propylene glycol sebacate). Specification 763,077 is referred to.