LUBRICATING COMPOSITION COMPRISING GLYCEROL MONOETHERS

Abstract

Disclosed is a lubricating composition including: at least one base oil; and at least one glycerol monoether characterised in that one of the alcohol functions of the glycerol forms an ether function with a linear or branched, alkyl or alkylene R group including 6 or 7 carbon atoms, the composition being an engine lubricant.

Claims

1-9. (canceled)

10. A lubricating composition comprising: at least one base oil; and at least one glycerol mono-ether, characterized in that one of the alcohol functions of glycerol forms an ether function with a linear or branched alkyl or alkylene group R comprising 6 or 7 carbon atoms, the composition being an engine lubricant.

11. The lubricating composition of claim 10 comprising: at least one base oil; and at least one glycerol mono-ether of formula (I) or (II), taken alone or as a mixture ##STR00008## in which R represents a linear or branched alkyl or alkylene group comprising 6 or 7 carbon atoms.

12. The lubricating composition according to claim 10 wherein R represents a linear or branched alkyl or alkylene group comprising 6 carbon atoms.

13. The lubricating composition according to claim 10 comprising from 0.01% to 5% by weight, of glycerol mono-ether.

14. A method of lubricating an engine comprising the implementation of a lubricating composition according to claim 10.

15. The method according to claim 14 wherein the engine is a motor engine.

16. The method for reducing the friction in an engine comprising the implementation of a lubricating composition according to claim 10.

17. The method for reducing the fuel consumption of an engine comprising the implementation of a lubricating composition according to claim 10.

18. The method for reducing friction in an engine comprising the implementation of a glycerol mono-ether as defined in claim 10 in a lubricating composition of an engine.

19. The method for reducing the fuel consumption of an engine comprising the implementation of a glycerol mono-ether as defined in claim 10 in a lubricating composition of an engine.

20. The lubricating composition according to claim 11 comprising from 0.01 to 2% by weight of glycerol mono-ether of formula (I) or (II) taken alone or as a mixture.

21. The lubricating composition according to claim 10, comprising from 0.1 to 1.5% by weight of glycerol mono-ether characterized in that one of the alcohol functions of glycerol forms an ether function with a linear or branched alkyl or alkylene group R, wherein R represents a linear or branched alkyl or alkylene group comprising 6 carbon atoms.

Description

EXAMPLES

[0092] Compounds Used:

[0093] The different glycerol monoethers tested are described in Table I below. The synthetic route requires that the glycerol and fatty alcohol used is soluble one in the other. However, any fatty alcohol comprising 8 or more carbon atoms is not soluble in glycerol, wherein the corresponding glycerol ethers can not be synthesized according to the described synthetic route.

TABLE-US-00002 TABLE I Name Formula MEG C7P [00002] MEG C7S [00003] MEG C6P [00004] MEG C5P [00005] MEG C4P [00006] MEG C3P [00007]

[0094] The operating conditions used for the preparation of each of the above glycerol monoethers are presented in the following Table II:

TABLE-US-00003 TABLE II Efficiency in Name Reactor Catalyst Temperature Period MEG (%) MEG B 2.5% mol 160 C. 24 h 15 C7P APTS MEG ROR 2.5% mol 150 C. 14 h 10 C7S APTS MEG R2L 1% mol 150 C. 24 h 25 C6P APTS MEG ROR 2.5% mol 150 C. 7 h 33 C5P APTS MEG MP 1% mol 150 C. 24 h 15 C4P APTS MEG ROR 2.5% mol 140 C. 5 h 8 C3P APTS

[0095] The reactors used are the following: [0096] B: Buchi glass reactor immersed in an oil bath, [0097] ROR: Fast opening reactor with a stirring propeller of 220 mL, [0098] MP: Multi-reactors consisting of six autoclaves of 75 mL, [0099] R2L: 2L stainless steel reactor with stirring blade.

[0100] The amount of catalyst is a molar amount relative to the amount of glycerol used.

[0101] For the synthesis of each of the above glycerol monoethers: [0102] the glycerol, the catalyst and the alcohol are mixed and react together; [0103] then the mixture thus obtained is first purified by decantation without solvent, then subjected to a liquid-liquid extraction and finally subjected to fractional distillation to recover the glycerol mono-ether.

[0104] The amount of glycerol monoethers obtained at the end of the reaction is measured by gas chromatography.

[0105] TGA Measurements

[0106] Thermogravimetric analysis (TGA) gives the mass loss of a sample as a function of temperature. The sample is heated according to programmed temperature ramps. The mass losses are determined using a scale that continuously measures the mass of the sample during its rise in temperature. The results of these TGA measurements on the various glycerol monoethers above are described in Table III.

TABLE-US-00004 TABLE III % of weight loss Temperature ( C.) MEG C3P 100% 169.5 C. MEG C4P 100% 186.6 C. MEG C5P 100% 192.4 C. MEG C6P 100% 216.1 C. MEG C7P 100% 222.9 C. MEG C7S 100% 195.1 C.

[0107] Thus short glycerol monoethers (MEG C3P and MEG C4P) have a loss of mass of 100% for lower temperatures, and especially less than 190 C. which makes them difficult to use in an engine application or even incompatible with such an application.

[0108] Conversely, the glycerol monoethers according to the invention (MEG CSP, MEG C6P, MEG C7P and MEG C7S) have a loss of mass of 100% for higher temperatures, and, in particular, may be greater than 200 C. which makes them fully compatible with use in a lubricating composition for a engine application.

[0109] Characterization Tests

[0110] In order to characterize the behavior of the compositions according to the invention, two series of tests were performed.

[0111] The HFRR (High Frequency Reciprocating Rig) test is used to evaluate the performance of fuels and lubricants in terms of friction in the mixed/limit regime.

[0112] This test involves fixing a steel plane, on which the lubricating composition to be tested is placed, in a heating block. A steel ball subjected to a certain load is then brought into contact with the lubricating composition and the steel plane before being vibrated. The vibration frequency and the load applied to the ball as well as the temperature at which the lubricating composition is subjected are adjustable. This test makes it possible to obtain a coefficient of friction curve as a function of the duration of the test.

[0113] In practice, the test lasts 30 min, the ball travels back and forth 2 mm at a frequency of 20 Hz, an average shear rate of 40 mm.s.sup.1 (limit regime). At the stop point of the ball, the speed is zero which places this test well in a limited and mixed lubrication regime. A load of 200 g is applied on the ball, which corresponds to a pressure of 800 MPa. The oil is heated to 100 C.

[0114] The MTM test (Traction Machine or Mini Traction Machine) makes it possible to evaluate the performance of lubricants in terms of friction in the mixed/hydrodynamic regime. This test consists in setting in relative motion a steel ball and a steel plane, at different speeds, allowing definition of the % SSR (ratio of the speed of slip/drive speed or Slide-to-Roll Ratio) which corresponds at the slip speed/drive speed.

[0115] The tests consist of a 120 min accumulation period where the ball rotates at 100 mm.s.sup.1 (hydrodynamic regime) with a % SSR of 50%, for a load of 1.1 GPa and an oil temperature 100 C.

[0116] A friction modifier is considered effective if it lowers the coefficient of friction. The different glycerol monoethers are tested in a reference lubricating composition whose composition is given in Table IV below.

TABLE-US-00005 TABLE IV Description Content (%) Base oil 1 Group III (kinematic 59.4 viscosity measured at 100 C. according to ASTM D556 = 4 mm.sup.2/s), Base oil 2 Group IV (kinematic 20 viscosity measured at 100 C. according to ASTM D556 = 6 mm.sup.2/s) Viscosity modifier Poly(isoprene-styrene- 6.6 hydrogenated) Pour point depressant polymer poly (alkylmethacrylate) 0.2 Antioxidant Diphenylamine 1.5 Additive package P6003 marketed by the 12.3 company Infineum

[0117] Each glycerol mono-ether is added at a content of 1% by weight relative to the total weight of the reference lubricating composition. The various lubricating compositions tested are described in Table V below.

TABLE-US-00006 TABLE V Composition 1 Composition 2 Composition 3 Composition 4 Composition 5 Composition 6 Composition 7 Reference 99 99 99 99 99 99 99 composition MEG C3P 1 MEG C4P 1 MEG C5P 1 MEG C6P 1 MEG C7P 1 MEG C7S 1 Glycerol 1 mono- oleate

Example 1

HFRR Tests

[0118] Table VI below represents the coefficients of friction of the reference composition and compositions 3, 4, 5 and 6; the values were taken after 900 seconds of testing.

TABLE-US-00007 TABLE VI Reference lubricating composition Composition 3 Composition 4 Composition 5 Composition 6 Coefficient 0.131 0.112 0.119 0.119 0.119 of friction at 900 seconds

[0119] Thus, all of the lubricating compositions according to the invention (compositions 3 to 6) significantly lower the coefficient of friction on this HFRR test under severe conditions.

Example 2

MTM Tests

[0120] As previously described, the MTM tests will probe the performance of the friction modifiers under less severe conditions than the HFRR test but are nevertheless representative of operating points of certain driving members. Table VII below indicates the values of the coefficients of friction of compositions 1, 2, 4, 5, 6 and 7; the values were taken after 6120 seconds of testing.

TABLE-US-00008 TABLE VII Coefficient of friction Composition 1 0.063 Composition 2 0.045 Composition 4 0.041 Composition 5 0.039 Composition 6 0.040 Composition 7 0.045

[0121] Thus, the lubricating compositions 4 to 6 according to the invention significantly lower the coefficient of friction on this MTM test in comparison with the comparative compositions 1 and 2 (comprising respectively a C.sub.3 and C.sub.4 glycerol mono-ether) or comparative composition 7 (comprising glycerol mono-oleate)).

Example 3

Engine Tests

[0122] In order to confirm the good results expressed on tribological tests, the composition 3 and the composition 6 were evaluated comparatively by the implementation of the motor test described below:

[0123] During the test, the fluid temperature (water/oil) is regulated. The engine is then positioned at a selected operating point (rpm/torque) and the fuel consumption is then measured at this point. A consumption map is thus produced by this means. The test engine is a Renault R9M engine.

[0124] Table VIII shows the gains in terms of % fuel consumption compared to the reference composition at a temperature (water/oil) set at 90 C. The threshold of significance of the test is equal to 0.15%.

TABLE-US-00009 TABLE VIII Regime Couple Composition 6 Composition 3 2500 160 0.14 0.31 2000 160 0.24 0.44 1500 160 0.19 0.35 2500 90 0.37 0.61 2000 90 0.06 0.50 1500 90 0.28 0.60 2500 40 0.42 0.88 2000 40 0.58 0.82 1500 40 0.71 0.79 849 2 1.96 0.95 Average heat 0.49 0.62 gain

[0125] Thus the lubricating compositions according to the invention significantly improve the fuel consumption, especially when hot.