LUBRICATING COMPOSITION

Abstract

In the field of lubricating compositions, notably lubricant compositions for automobile vehicles, in particular to the field of lubricant compositions for transmissions, for gear boxes or for bridges, there is disclosed a lubricating composition including at least 30% by weight of the composition of at least one monoester, at least one polyalphaolefin oil (PAO) for which the kinematic viscosity measured at 100 C. ranges from 40 to 3,000 mm.sup.2.Math.s.sup.1 and at least one polyalphaolefin oil (PAO) for which the kinematic viscosity measured at 100 C. ranges from 1.5 to 10 mm.sup.2.Math.s.sup.1. Also disclosed is the use of this lubricating composition for reducing the fuel consumption of a vehicle equipped with a transmission, notably with a bridge or a gear box, lubricated by this lubricating composition.

Claims

1-23. (canceled)

24. A lubricating composition comprising (a) at least 30% by weight of the composition of at least one monoester of formula (I) ##STR00002## wherein R.sup.1 represents a hydrocarbon group, either saturated or unsaturated, linear or branched, comprising from 14 to 24 carbon atoms; R.sup.2 represents a hydrocarbon group, either saturated or unsaturated, linear or branched, comprising from 2 to 18 carbon atoms; (b) at least one polyalphaolefin oil (PAO) for which the kinematic viscosity measured at 100 C. according to the ASTM D445 standard ranges from 40 to 3,000 mm.sup.2.Math.s.sup.1; (c) at least one polyalphaolefin oil (PAO) for which the kinematic viscosity measured at 100 C. according to the ASTM D445 standard ranges from 1.5 to 10 mm.sup.2.Math.s.sup.1.

25. The lubricating composition according to claim 24 comprising from 30 to 70% of the monoester of formula (I) by weight of said composition.

26. The lubricating composition according to claim 24 for which R.sup.1 is a saturated group and R.sup.2 is an unsaturated group.

27. The lubricating composition according to claim 24 for which R.sup.1 is an unsaturated group and R.sup.2 is a saturated group.

28. The lubricating composition according to claim 24 for which R.sup.1 and R.sup.2 are saturated groups.

29. The lubricating composition according to claim 24 for which R.sup.1 and R.sup.2 are unsaturated groups.

30. The lubricating composition according to claim 24 for which R.sup.1 represents a hydrocarbon group, either saturated or unsaturated, linear or branched, comprising from 14 to 20 carbon atoms; or R.sup.2 represents a hydrocarbon group, either saturated or unsaturated, linear or branched, comprising from 3 to 14 carbon atoms; or R.sup.1 is a linear group and R.sup.2 is a branched group; or R.sup.1 is a branched group and R.sup.2 is a linear group; or R.sup.1 and R.sup.2 are linear groups; or R.sup.1 and R.sup.2 are branched groups.

31. The lubricating composition according to claim 24 for which only R.sup.1, only R.sup.2 or R.sup.1 and R.sup.2 are selected from among a linear saturated group; a branched saturated group comprising from 1 to 5 branched chains; a branched saturated group for which the branched chains comprise from 1 to 5 carbon atoms; a branched saturated group comprising from 1 to 5 branched chains and for which the branched chains comprise from 1 to 5 carbon atoms.

32. The lubricating composition according to claim 24 for which the monoester is selected from among stearates; and oleates.

33. The lubricating composition according to claim 24 for which the monoester is selected from among alkene monoesters and alkyl monoesters.

34. The lubricating composition according to claim 24 for which the kinematic viscosity of the polyalphaolefin oil (b), measured at 100 C. according to the ASTM D445 standard, ranges from 40 to 1,500 mm.sup.2.Math.s.sup.1.

35. The lubricating composition according to claim 24 for which the average molecular mass by weight of the polyalphaolefin oil (b) is greater than 2,500 Da.

36. The lubricating composition according to claim 24 for which the kinematic viscosity of the polyalphaolefin oil (c), measured at 100 C. according to the ASTM D445 standard, ranges from 1.5 to 10 mm.sup.2.Math.s.sup.1.

37. The lubricating composition according to claim 24 for which the average molecular mass by weight of the polyalphaolefin oil (c) is less than 500 Da.

38. The lubricating composition according to claim 24 comprising from 5 to 30% by weight of the composition of a polyalphaolefin oil (b).

39. The lubricating composition according to claim 24, comprising from 5 to 70% by weight of the composition of a polyalphaolefin oil (c).

40. The lubricating composition according to claim 24 comprising one, two or three monoesters (a); or one, two or three polyalphaolefin oils (b); or one, two or three polyalphaolefin oils (c); or comprising a single monoester (a), a single polyalphaolefin oil (b) and a single polyalphaolefin oil (c).

41. The lubricating composition according to claim 24 also comprising at least one additive.

42. A method of lubricating a system of gears comprising a step of applying at least one lubricating composition according to claim 24 to said system of gears.

43. A method of reducing the fuel consumption of an engine comprising a step of applying at least one lubricating composition according to claim 24 to the engine.

44. A method of reducing the fuel consumption of a vehicle equipped with a transmission comprising a step of lubricating said transmission with at least one lubricating composition according to claim 24.

45. A method of reducing the traction coefficient of a transmission oil comprising a step of incorporating at least one lubricating composition according to claim 24 into said transmission oil.

46. A method of reduction of the traction coefficient of a lubricating composition comprising at least one heavy PAO (b) and at least one lightweight PAO (c), comprising a step of incorporating at least 30% by weight of a composition of a monoester (a) of formula (I) defined according to claim 24 into said lubricating composition.

Description

EXAMPLE 1: PREPARATION OF LUBRICATING COMPOSITIONS ACCORDING TO THE INVENTION

[0079] Decyl oleate (Starinerie Dubois) is mixed with a heavy PAO (a product Spectrasyn mPAO150 from ExxonKV100 of about 150 mm.sup.2.Math.s.sup.1), a first lightweight PAO (product Spectrasyn 6 from ExxonKV100 of about 6 mm.sup.2.Math.s.sup.1) and a second lightweight PAO (product Spectrasyn 8 from of ExxonKV100 of about 8 mm.sup.2.Math.s.sup.1).

[0080] In an analogue way, a second composition according to the invention is prepared wherein the decyl oleate is replaced with butyl stearate (Starinerie Dubois). The respective amounts of the different constituents are shown in table 1 and are expressed in a mass % based on the mass of the final composition. The viscosity index (VI) is measured according to the ASTM D2270 standard.

TABLE-US-00002 TABLE 1 Composition (1) Composition (2) according to the according to the invention (%) invention (%) decyl oleate 30 0 butyl stearate 0 30 heavy PAO (b) 8 10 lightweight PAO (c1) 30 4 (Spectrasyn 6) lightweight PAO (c2) 32 56 (Spectrasyn 8) Viscosity index (VI) 174 176

COMPARATIVE EXAMPLE 1: PREPARATION OF COMPARATIVE LUBRICATING COMPOSITIONS

[0081] Similarly to example 1, 3 comparative lubricating compositions are prepared by replacing decyl oleate respectively with methyl oleate (Starinerie Dubois), by methyl stearate (Starinerie Dubois) and by the isononyl isononanoate (Starinerie Dubois). The respective amounts of the different constituents are shown in table 2 and are expressed in mass % based on the mass of the final composition.

TABLE-US-00003 TABLE 2 Comparative Comparative Comparative composition (1) composition (2) composition (3) (%) (%) (%) methyl oleate 30 0 0 methyl stearate 0 30 0 isononyl isononanoate 0 0 30 heavy PAO (b) 13 12.3 13 lightweight PAO (c1) 0 0 57 (Spectrasyn 6) lightweight PAO (c2) 57 57.7 0 (Spectrasyn 8) Viscosity index (VI) 182 180 173

EXAMPLE 2: COMPARISON OF THE TRACTION COEFFICIENT OF THE COMPOSITIONS ACCORDING TO THE INVENTION AND OF THE COMPARATIVE LUBRICATING COMPOSITIONS

[0082] The traction coefficient of the prepared lubricating compositions is evaluated and the obtained results are shown in table 3.

TABLE-US-00004 TABLE 3 Composition Composition (1) (2) according according Comparative to the to the composition (3) traction coefficient (MTM: 0.034 0.033 0.048 T = 40 C., V.sub.e = 1 m..sup.1, SRR = 20% load = 75N)

[0083] The lubricating compositions according to the invention have a better traction coefficient than the comparative lubricating compositions.

EXAMPLE 3: COMPARISON OF THE OXIDATION RESISTANCE PROPERTIES OF THE LUBRICATING COMPOSITION (1) ACCORDING TO THE INVENTION AND OF THE COMPARATIVE LUBRICATING COMPOSITION (1)

[0084] The oxidation resistance properties of the prepared lubricating compositions are evaluated according to the method A of the standard CEC-L48-A-00 and the obtained results are shown in the table 4. The more the variation of KV 100 (R KV 100) is significant, the lower is the resistance to oxidation. The larger the variation of KV 40 (R KV 40) is significant, the lower is the resistance to oxidation.

[0085] The more significant the variation of TAN (Total Acid Number, R TAN), the lower is the resistance to oxidation. The larger the PAI (Peak Area Increase), the lower is the resistance to oxidation.

TABLE-US-00005 TABLE 4 Lubricating composition (1) according to the Comparative lubricating invention composition (1) Duration (h) 192 192 initial KV 100 (mm.sup.2 .Math. s.sup.1) 6.68 6.79 final KV 100 (mm.sup.2 .Math. s.sup.1) 7.88 11.08 R KV 100 (%) 18.01 63.18 initial KV 40 (mm.sup.2 .Math. s.sup.1) 31.13 30.44 initial KV 40 (mm.sup.2 .Math. s.sup.1) 37.79 60.15 R KV 40 (%) 21.39 97.60 Insoluble compounds 0 4 cm at the bottom initial TAN 1.87 1.46 final TAN 3.48 4.12 R TAN (%) 1.6 2.7 PAI <20 34

[0086] The lubricating composition according to the invention has a resistance to oxidation which is greater than that of the comparative lubricating composition. No deposit of insoluble compounds occurs with the lubricating composition according to the invention.

[0087] These results also show that the lubricating compositions according to the invention retain a high viscosity index and are therefore compatible with applications as lubricants for transmissions or engine lubricants.