AN AMMONIUM-BASED IONIC LIQUID AND ITS USE AS A LUBRICANT ADDITIVE

Abstract

An ammonium-based ionic liquid compound including a tri-n-octylmethylammonium cation and a carboxylate anion. A lubricant composition including it, and its use as a detergent and/or anti-corrosion additive in a lubricant, in particular a marine lubricant.

Claims

1-15. (canceled)

16. A method to reduce and/or limit and/or prevent and/or delay the formation of deposits or to reduce the deposits already present in the internal parts of a combustion engine, the method comprising at least a step of application to said engine of an ammonium-based ionic liquid compound responds to formula (I)
[CAT.sup.+][X.sup.−]  (I) wherein [CAT.sup.+] is tri-n-octylmethylammonium and [X.sup.−] is selected from compounds of formula (IA): ##STR00005## wherein R is selected from linear or branched alkyl and alkenyl groups comprising from 2 to 8 atoms of carbon.

17. The method according to claim 16 wherein in formula (IA) R represents a linear or branched alkyl group comprising from 2 to 8 atoms of carbon.

18. The method according to claim 17 wherein in formula (IA) R represents a linear or branched alkyl group comprising from 4 to 8.

19. The method according to claim 18 wherein R represents a linear or branched alkyl group comprising from 5 to 7 carbon atoms.

20. The method according to claim 19 wherein [X.sup.−] is 2-ethylhexanoate.

21. The method according to claim 16 wherein the lubricant composition is a marine lubricant.

22. The method according to claim 16, wherein the ammonium-based ionic liquid compound of formula (I) is applied in a lubricant composition comprising: from 30.0 to 99.95% of at least one base oil, from 0.05 to 15.0% of ammonium-based ionic liquid compound of formula

23. A lubricant composition comprising: from 30.0 to 94.0% of at least one base oil, from 0.05 to 15% of at least one ammonium-based ionic liquid of formula (I),
[CAT.sup.+][X.sup.−]  (I) wherein [CAT.sup.+] is tri-n-octylmethylammonium and [X.sup.−] is selected from compounds of formula (IA): ##STR00006## wherein R is selected from linear or branched alkyl and alkenyl groups comprising from 2 to 8 atoms of carbon, and from 1 to 35% of at least one detergent selected from neutral and overbased detergents, other than the ionic liquid, having a Total Base Number according to ASTM D2896 of from 20 to 450 mg KOH/g the percentages being defined by weight of component as compared to the total weight of the composition.

24. The lubricant composition according to claim 23, wherein the percentage by weight of ammonium-based ionic liquid relative to the total weight of lubricant composition is chosen such that the BN provided by the ammonium-based ionic liquid represents at least 3% of the total BN of said lubricant composition.

25. The lubricant composition according to claim 23, wherein the percentage by weight of ammonium-based ionic liquid of formula (I), relative to the total weight of lubricant composition, is chosen such that the BN provided by the compounds of formula (I) represents a contribution of at least 0.5 milligrams of potash per gram of lubricant, to the total BN of said lubricant composition.

26. The lubricant composition according to claim 23, which has a Total Base Number (TBN) value according to ASTM D2896 of above 5 mg KOH/g.

27. The lubricant composition according to claim 23, which has a kinematic viscosity at 100° C. superior or equal to 5.6 mm.sup.2/s and inferior or equal to 21.9 mm.sup.2/S.

28. A lubricant composition comprising: from 30.0 to 99.95% of at least one base oil, from 0.05 to 15.0% of tri-n-octylmethylammonium 2-ethylhexanoate, the percentages being defined by weight of component as compared to the total weight of the composition.

29. The lubricant composition according to claim 28, wherein it comprises at least one detergent selected from neutral and overbased detergents, other than the ionic liquid, having a Total Base Number according to ASTM D2896 of from 20 to 450 mg KOH/g.

Description

EXAMPLES

[0155] Materials and Methods:

[0156] Tri-n-octylmethylammonium methylcarbonate (CAS No 488711-07-5) is available from ABCR GmbH.

[0157] 2-ethylhexanoic acid (CAS No 149-57-5) is available from Merck.

[0158] I—Synthesis of Tri-n-Octylmethylammonium 2-Ethylhexanoate (IL 1):

[0159] To a solution of tri-n-octylmethylammonium methylcarbonate 30% in methanol (1774 g, 4 mol), 576.8 g (4 mol) of 2-ethylhexanoic acid were added slowly and under stirring over a period of 5 hours using a piston pump. The temperature of the reaction was kept under 25° C. CO.sub.2 evolution was monitored and stirring was controlled in order to avoid foaming. After completion of the addition, the reaction mixture was stirred at room temperature for 24 hours, then the pH of the medium was adjusted to pH=9 through addition of either tri-n-octylmethylammonium methylcarbonate or 2-ethylhexanoic acid. 60 ml of activated charcoal were added to the mixture and the latter was further vigorously stirred for 13 hours at room temperature. The charcoal was filtrated over a glass frit filter, the solvent evaporated at 38° C. under reduced pressure. The obtained slightly yellow oil was further dried at 35° C. under a vacuum of 10.sup.-2 mbar for 168 hours and under vigorous stirring until the water content was below 0.1%, as measured by Karl-Fischer titration.

[0160] The base number of IL1 is 114 mg KOH/g according to ASTM D2896.

[0161] Solubility Test:

[0162] In order to check that the ammonium-based ionic liquid is oil-soluble, the following test has been achieved:

[0163] 100 mL of the lubricant composition comprising IL1 and the base oil is introduced into two reaction tubes. One of the tubes is maintained at room temperature (between 15 and 25° C.) and the other reaction tube is placed in an oven at 60° C.

[0164] After three months, the lubricant composition of both reaction tubes was limpid. Thus, the prepared ionic liquid IL1 is soluble in the oil.

[0165] II—Preparation of the Lubricant Composition:

[0166] Lubricant compositions are prepared by mixing the base oil with the additives listed in Table 1 below at 60° C. with the corresponding proportions. The percentages correspond to weight percent with regards to the total weight of the composition.

[0167] Composition C1 is a comparative example. Composition C2 is according to the invention.

TABLE-US-00002 TABLE 1 formulation of lubricant compositions Composition C1 C2 Base oil .sup.(1) (%) 89.67 88.4 IL1 (%) 2.6 Dtg 1 .sup.(2) (%) 4.6 4 Dtg 2 .sup.(2) (%) 5.7 5 AF .sup.(3) (%) 0.03 0.03 TBN (Total base number in mg KOH/g of 25.1 25.5 composition according to ASTM D2896) .sup.(1) Group I mineral oil XX having a viscosity at 40° C. of 112 cSt measured according to ASTM D7279 .sup.(2) Detergents: Dtg1: Salicylate of TBN = 225 mg KOH/g according to ASTM D2896, Dtg 2: Phenate of TBN = 260 mg KOH/g according to ASTM D2896 .sup.(3) AF: anti-foaming agent.

[0168] III: Test Method 1—Heat Resistance and Detergency of Lubricant Compositions:

[0169] The heat resistance of lubricant compositions according to the invention is evaluated by performing the ECBT test on aged oil.

[0170] Principle: the heat resistance of the lubricant composition Ci was thus evaluated by means of the ECBT test on aged oil, via which the mass of deposits (in mg) generated under given conditions is determined. The lower this mass, the better the heat resistance and thus the better the cleanliness of the engine.

[0171] This test simulates the behaviour of the lubricant composition when it is injected onto the hot parts of the engine and especially onto the top of the piston.

[0172] Equipment used: the test was performed at a temperature of 310° C. It uses aluminium beakers which simulate the form of pistons. The beakers were placed in a glass container; the lubricant composition being maintained at a controlled temperature of about 60° C. The lubricant was placed in these containers, which were themselves equipped with a metal brush partially immersed in the lubricant. This brush is driven in a rotary motion at a speed of 1000 rpm, which creates a projection of lubricant onto the inner surface of the beaker. The beaker was maintained at a temperature of 310° C. by means of a heating electrical resistance, regulated by a thermocouple. This projection of lubricant was continued throughout the test for 12 hours.

[0173] This procedure makes it possible to simulate the formation of deposits in the piston-ring assembly. The result is the weight of deposits measured in mg on the beaker.

[0174] A detailed description of this test is given in the publication “Research and Development of Marine Lubricants in ELF ANTAR France- The relevance of laboratory tests in simulating field performance” by Jean-Philippe ROMAN, Marine Propulsion Conference 2000-Amsterdam-29-30 Mar. 2000.

[0175] Results: the lubricant composition according to the invention C2 provides 110 mg of deposits whereas the comparative lubricant C1 provides 499 mg of deposits.

[0176] Thus, the ammonium-based ionic liquid of formula (I) according to the present invention has good detergency properties since it allows reducing the deposits in pieces of a motor.

[0177] IV: Test Method 2—Anti-Corrosion Properties:

[0178] Equipment used: The apparatus used to evaluate the passivation of the compounds tested consists of a beaker of suitable size (usually 500 to 1000 mL), a temperature-regulating device such as a hot plate, and a specimen support system. 200 mL of lubricant are continuously mixed by a suitable stirring mechanism, such as a magnetic stirrer or others. Using a dosing syringe or pump, a well-defined amount of sulfuric acid is added to the lubricant drop by drop, to expose the metallic test samples to severely acidic corrosive conditions. The quantity of sulfuric acid is determined to have 90% of the TBN of the oil neutralized.

[0179] The effects of corrosion are determined by visual changes on the metallic specimen.

[0180] Results: The results obtained with compositions C1 and C2 described above are shown in table 3 below. Corrosion is rated on a scale of 1 to 5.

[0181] 1 means that the test sample is very corroded and 5 means it is hardly corroded or not corroded at all.

TABLE-US-00003 TABLE 3 Composition C1 C2 Corrosion observed 1 5