Lubricant composition having improved emulsion stability

Abstract

Disclosed is a lubricant composition comprising: - at least one base oil, - 0.1 to 13% by mass of at least one viscosity index improver, - at least one organic molybdenum compound having a molybdenum element content of at least 400 ppm by mass, - at least one first detergent additive selected from magnesium salts of carboxylic acids, sulfonates, salicylates, naphthenates, phenates, and mixtures thereof, - optionally, at least one second detergent additive selected from calcium salts of carboxylic acids, sulfonates, salicylates, naphthenates, phenates, and mixtures thereof, wherein the total content of magnesium and calcium elements in relation to the total mass of the lubricant composition is at least 1000 ppm by mass.

Description

Technical Field

[0001] The present invention relates to the lubrication of a vehicle having at least one combustion engine. More particularly, the present invention relates to the lubrication of the engines of hybrid vehicles such as plug-in hybrid vehicles and hybrid vehicles having a range extender.

Background Art

[0002] Hybrid vehicles have two prime movers, an internal combustion engine and an electric motor. In most hybrid vehicles, the combustion engine drives the wheels and is assisted by the electric motor. The battery supplies the electricity necessary for the operation of the electric motor, and in the case of conventional hybrid vehicles, this battery is charged during braking and deceleration by a kinetic energy recovery system (KERS) built into the vehicle.

[0003] There are many different hybrid vehicle technologies. Among these hybrid technologies, the following are particularly worthy of mention: - Micro hybrid vehicles (also known as light hybrids). These vehicles are equipped with a "stop & start" system, recover the energy generated by braking to charge the battery, and the battery can temporarily assist the internal combustion engine. - Mild hybrid vehicles, which include electric assist during acceleration. - Full hybrid vehicles are fully hybridized vehicles. At low speeds, when the battery is being charged, the electric motor takes care of both starting and propulsion. At high speeds, or when the battery is discharging, the internal combustion engine takes over, and when more power is required (e.g., during acceleration), both prime movers operate together. Thus, it is possible to drive for several kilometers with the combustion engine stopped.

[0004] Other supplementary technologies, namely plug-in hybrid vehicles and hybrid vehicles with range extenders, have been developed in recent years. So-called plug-in hybrid vehicles have a combustion engine and an electric motor, and the battery can be charged from the power supply network. As a result, such vehicles can be driven in 100% electric mode over a distance of several tens of kilometers, for example 50 kilometers. In a hybrid vehicle with an auxiliary power unit called a "range extender", only the electric motor drives the wheels. This electric motor is powered by the battery over a distance of several tens of kilometers. When the battery reaches a certain charge threshold level (for example, approximately 30%), the internal combustion engine starts and drives the current generator to produce the electricity necessary for charging the battery and maintaining the operation of the electric motor.

[0005] Lubricant compositions, and more particularly lubricant compositions used for lubricating combustion engines, generally contain a small amount of water, especially water generated by the lubricant directly adsorbing water contained in the air, or even water generated from the condensation of ambient water vapor. Lubricant compositions typically contain 0 to 10% water. Although present in trace amounts, the water in the lubricant composition is the cause of problems such as cold starting of the combustion engine, corrosion, and early wear. Therefore, in order to prevent these phenomena, it is necessary to maintain this water in the form of an emulsion.

[0006] However, especially in the engines of plug-in hybrid type or hybrid vehicles incorporating a range extender, the combustion engine is used less frequently, and as a result, problems related to demixing of the lubricant composition are particularly likely to occur. Since the lubricant composition remains stationary, the emulsion becomes unstable, and the water separates from the oil phase, thus forming a continuous phase.

[0007] The same problem is also observed when only combustion engines, particularly conventional vehicles (non-hybrid vehicles) equipped with gasoline engines, are operated only occasionally. Since the lubricant composition does not circulate regularly within the engine, the water present tends to separate from the rest of the lubricant composition and form a continuous phase.

[0008] Therefore, it is necessary to provide a specific lubricant composition that can effectively lubricate such an engine system and at the same time prevent the demixing problem.

Summary of the Invention

Problems to be Solved by the Invention

[0009] One object of the present invention is to provide a lubricant composition that enables effective lubrication of an internal combustion engine, particularly an engine of a vehicle having a plug-in hybrid vehicle or a range extender.

[0010] Another object of this patent application is to provide a lubricant composition having improved emulsion stability. Specifically, an object of the present invention is to provide a lubricant composition that can maintain the existing water in the form of a stable emulsion.

Means for Solving the Problems

[0011] These objects are achieved by - at least one base oil, - at least one viscosity index improver in an amount of 0.1 to 13% by mass based on the total mass of the lubricant composition, - at least one organic molybdenum compound having a molybdenum element content of at least 400 ppm by mass based on the total mass of the lubricant composition, - at least one first detergent additive selected from magnesium salts of carboxylic acids, sulfonates, salicylates, naphthenates, phenates, and mixtures thereof, - Optionally, at least one second cleaning additive selected from carboxylic acids, sulfonates, salicylates, naphthenates, calcium salts of phenates, and mixtures thereof, A lubricant composition comprising This patent application for a lubricant composition achieves a total content of magnesium and calcium elements of at least 1000 ppm by mass in relation to the total mass of the lubricant composition.

[0012] [Base oil] The base oil used in the lubricant composition according to the present invention belongs to Groups I to V according to the categories defined in the American Petroleum Institute (API) classification, and may be a mineral or synthetically derived oil (or its equivalent according to the ATIEL [European Lubricant Industry Technical Association] classification) (Table A), optionally recycled, or a mixture thereof.

[0013]

Table 1

[0014] The mineral base oils according to the present invention include all types of base oils obtained by atmospheric and vacuum distillation of crude oil followed by refining operations such as solvent extraction, deasphalting, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization, and hydrofinishing.

[0015] Optionally recycled mixtures of synthetic and mineral oils may also be used.

[0016] Generally, regarding the use of different lubricant base oils for manufacturing the lubricant composition according to the present invention, there are no restrictions other than that they must have appropriate properties suitable for use in vehicle engines or transmissions, particularly from the viewpoints of viscosity, viscosity index, sulfur content, and oxidation resistance.

[0017] The base oil of the lubricant composition according to the present invention can also be selected from specific esters of carboxylic acids and alcohols and synthetic oils such as polyalphaolefins. The polyalphaolefin used as the base oil has, for example, a viscosity of 1.5 to 15 mm 2 / s at 100 °C according to the ASTM D445 standard and is obtained from monomers containing 4 to 32 carbon atoms, such as octene or decene. Their average molecular weight is generally between 250 and 3000 according to the ASTM D5296 standard.

[0018] The lubricant composition according to the present invention can contain at least 50% by weight of base oil in relation to the total weight of the composition. More preferably, the lubricant composition according to the present invention contains at least 60% by weight, or actually at least 70% by weight of base oil in relation to the total weight of the composition. Particularly more preferably, the lubricant composition according to the present invention contains 75 to 95% by weight of base oil in relation to the total weight of the composition.

[0019] [Viscosity Index Improver] The lubricant composition according to the present invention contains at least one viscosity index improver for improving the viscosity index of the lubricant composition.

[0020] For the purposes of the present invention, the term "viscosity index improver" is understood to refer to chemical compounds that help ensure that the lubricant composition has good low-temperature flow properties and a minimum viscosity at high temperatures.

[0021] Examples of viscosity index improver polymers that may be mentioned include polymer esters; hydrogenated or non-hydrogenated homopolymers or copolymers of styrene, butadiene and isoprene; homopolymers or copolymers of olefins such as ethylene or propylene; and polyacrylates and polymethacrylates (PMA).

[0022] The lubricant composition according to the present invention typically contains 0.1 to 13% by weight of viscosity index improver(s) in relation to the total weight of the lubricant composition.

[0023] Preferably, the lubricant composition according to the present invention contains 0.5 to 12% by weight, more preferably 1 to 10% by weight, and even more preferably 5 to 10% by weight of a viscosity index improver(s) in relation to the total weight of the lubricant composition.

[0024] [Organic molybdenum compound] The lubricant composition according to the present invention contains at least one organic molybdenum compound.

[0025] The term "organic molybdenum compound" according to the present invention is understood to refer to any fat-soluble (oil-soluble) organic molybdenum compound.

[0026] The organic molybdenum compound according to the present invention can be selected from an organic molybdenum complex having at least one molybdenum chemical element (Mo), preferably at least two molybdenum chemical elements (Mo), and at least one ligand such as a carboxylate ligand, an ester ligand, an amide ligand, a dithiophosphate ligand or a dithiocarbamate ligand.

[0027] For example, an organic complex of molybdenum having carboxylate, ester and amide can be obtained by reacting molybdenum oxide or ammonium molybdate with a fatty substance, glyceride, fatty acid or fatty acid derivative (ester, amine, amide, etc.).

[0028] For the purpose of the present invention, the carboxylate ligand, ester ligand and amide ligand do not contain sulfur and phosphorus.

[0029] In one embodiment, the organic molybdenum compound of the present invention is mainly prepared by reacting a molybdenum source, which can be, for example, molybdenum trioxide, with an amine derivative and a fatty acid containing, for example, 4 to 36 carbon atoms, such as a fatty acid contained in a vegetable or animal oil, and is selected from complexes of molybdenum having an amide ligand.

[0030] The synthesis of such compounds is described, for example, in US Patent No. 4,889,647, European Patent No. 0,546,357, US Patent No. 5,412,130 or European Patent No. 1,770,153.

[0031] According to a preferred embodiment, the organomolybdenum compound is selected from dinuclear organomolybdenum compounds.

[0032] For the purposes of the present invention, the term "dinuclear organomolybdenum compound" is understood to refer to an organomolybdenum compound in which two molybdenum atoms are present in the nucleus. The compound is also referred to as a dimeric organomolybdenum compound.

[0033] In a preferred embodiment of the present invention, the organomolybdenum compound is (i) a monoglyceride, diglyceride or triglyceride, or a fatty substance of the fatty acid type, and (ii) an amino source having the chemical formula (A):

Chemical formula

[0034] In one embodiment of the present invention, the organomolybdenum compound may contain 0.1 to 30% by weight, preferably 0.1 to 20% by weight, more preferably 2 to 8.5% by weight of molybdenum in relation to the total weight of the organomolybdenum complex.

[0035] Preferably, the organomolybdenum compound has the chemical formula (I):

Chemical formula

Chemical formula

[0036] Advantageously, the organic complex of molybdenum having the chemical formula (I) or (II) is (i) a monoglyceride, diglyceride or triglyceride, or a fatty substance of the fatty acid type, and (ii) diethanolamine or 2-(2-aminoethyl)aminoethanol, and (iii) a molybdenum source selected from molybdenum trioxide or molybdate, preferably ammonium molybdate, and is prepared by reaction therewith.

[0037] Even more advantageously, the organic complex of molybdenum having the chemical formula (I) is of the chemical formula (I-a):

Chemical formula

Chemical formula

[0038] As an example of the sulfur-free molybdenum complex according to the present invention, Molyvan855 (registered trademark) commercially available from Vanderbilt can be mentioned.

[0039] In another embodiment of the present invention, the organomolybdenum compound is selected from an organomolybdenum complex of molybdenum having a dithiophosphate ligand or an organomolybdenum complex of molybdenum having a dithiocarbamate ligand.

[0040] Within the scope of the gist of the present invention, an organomolybdenum complex of molybdenum having a dithiophosphate ligand is also called molybdenum dithiophosphate or Mo-DTP compound, and an organomolybdenum complex of molybdenum having a dithiocarbamate ligand is also called molybdenum dithiocarbamate or Mo-DTC compound.

[0041] In a more preferred embodiment of the present invention, the organomolybdenum compound is selected from molybdenum dithiocarbamate.

[0042] The Mo-DTC compound is a complex formed from a molybdenum metal nucleus bonded to one or more ligands, and the ligand is an alkyldithiocarbamate group. These compounds are well known to those skilled in the art.

[0043] In one embodiment of the present invention, the Mo-DTC compound may contain 1 to 40% by weight, preferably 2 to 30% by weight, more preferably 3 to 28% by weight, and advantageously 4 to 15% by weight of molybdenum in relation to the total weight of the Mo-DTC compound.

[0044] In another embodiment of the present invention, the Mo-DTC compound may contain 1 to 40% by weight, preferably 2 to 30% by weight, more preferably 3 to 28% by weight, and advantageously 4 to 15% by weight of sulfur in relation to the total weight of the Mo-DTC compound.

[0045] In a preferred embodiment of the present invention, the Mo-DTC compound is a dimer Mo-DTC compound.

[0046] Examples of dimer Mo-DTC compounds that may be mentioned include compounds as described in European Patent No. 0757093, European Patent No. 0719851, European Patent No. 0743354 or European Patent No. 1013749 and related preparation methods thereof.

[0047] The dimer Mo-DTC compound generally has the chemical formula (III):

Chemical formula

[0048] The term "alkyl group" within the scope of the gist of the present invention is understood to refer to a linear or branched, saturated or unsaturated hydrocarbon group containing 1 to 24 carbon atoms, preferably 4 to 18 carbon atoms.

[0049] In one embodiment of the present invention, the alkyl group is selected from the group consisting of methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, hexadecyl, stearyl, icosyl, docosyl, tetracosyl, triacontyl, 2-ethylhexyl, 2-butyloctyl, 2-butyldecyl, 2-hexyloctyl, 2-hexyldecyl, 2-octyldecyl, 2-hexyldodecyl, 2-octyldodecyl, 2-decyltetradecyl, 2-dodecylhexadecyl, 2-hexadecyloctadecyl, 2-tetradecyloctadecyl, myristyl, palmityl and stearyl.

[0050] The term "alkenyl group" within the scope of the gist of the present invention is understood to refer to a linear or branched hydrocarbon group containing 2 to 24 carbon atoms and having at least one double bond. The alkenyl group may be selected from vinyl, allyl, propenyl, butenyl, isobutenyl, pentenyl, isopentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl and olein.

[0051] The term "aryl group" within the scope of the gist of the present invention is understood to refer to a polycyclic aromatic hydrocarbon or an aromatic group, whether or not substituted with an alkyl group. The aryl group may contain 6 to 24 carbon atoms.

[0052] In one embodiment, the aryl group may be selected from the group consisting of phenyl, toluyl, xylyl, cumenyl, mesityl, benzyl, phenethyl, styryl, cinnamyl, benzhydryl, trityl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, nonylphenyl, decylphenyl, undecylphenyl, dodecylphenyl, phenylphenyl, benzylphenyl, phenyl-styrene, p-cumylphenyl and naphthyl.

[0053] Within the scope of the gist of the present invention, the term "cycloalkyl group" is understood to refer to a cyclic or polycyclic hydrocarbon, whether or not it is substituted with an alkyl group.

[0054] Within the scope of the gist of the present invention, the term "cycloalkenyl group" is understood to refer to a cyclic or polycyclic hydrocarbon containing at least one unsaturation, whether or not it is substituted with an alkyl group.

[0055] The cycloalkyl group and the cycloalkenyl group may contain 3 to 24 carbon atoms.

[0056] For the purposes of the present invention, the cycloalkyl group and the cycloalkenyl group may be selected from, but are not limited to, the group consisting of cyclopentyl, cyclohexyl, cycloheptyl, methylcyclopentyl, methylcyclohexyl, methylcycloheptyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, methylcyclopentenyl, and methylcyclohexenyl.

[0057] In a preferred embodiment of the present invention, R 3 , R 4 , R 5 and R 6 each independently represent an alkyl group containing 1 to 24 carbon atoms, preferably 4 to 18 carbon atoms, or an alkenyl group containing 2 to 24 carbon atoms.

[0058] In one embodiment of the present invention, X 3 , X 4 , X 5 and X 6 may be the same and may represent a sulfur atom.

[0059] In another embodiment of the present invention, X 3 , X 4 , X 5 and X 6 may be the same and may be an oxygen atom.

[0060] In another embodiment of the present invention, X 3 and X 4 may represent a sulfur atom, and X 5 and X 6 may represent an oxygen atom.

[0061] In another embodiment of the present invention, X 3 and X 4 may represent an oxygen atom, and X 5 and X 6 may represent a sulfur atom.

[0062] In another embodiment of the present invention, the ratio (S / O) of the number of sulfur atoms to the number of oxygen atoms in the Mo-DTC compound can vary from (1 / 3) to (3 / 1).

[0063] In another embodiment of the present invention, the Mo-DTC compound having the chemical formula (III) can be selected from symmetric Mo-DTC compounds, asymmetric Mo-DTC compounds, and combinations thereof.

[0064] The term "symmetric Mo-DTC compound" according to the present invention is understood to refer to a Mo-DTC compound having the chemical formula (V) in which the groups of R 3 , R 4 , R 5 and R 6 are the same.

[0065] The term "asymmetric Mo-DTC compound" according to the present invention is understood to refer to a Mo-DTC compound having the chemical formula (V) in which the groups of R 3 and R 4の are the same, the groups of R 5 and R 6 are the same, and the groups of R 3 and R 4 are different from the groups of R 5 and R 6 .

[0066] In a preferred embodiment of the present invention, the Mo-DTC compound is a mixture of at least one symmetric Mo-DTC compound and at least one asymmetric Mo-DTC compound.

[0067] In one embodiment of the present invention, R which are identical 3 and R 4 represent an alkyl group containing 5 to 15 carbon atoms, preferably 8 to 13 carbon atoms, and R which are identical 5 and R 6 represent an alkyl group containing 5 to 15 carbon atoms, preferably 8 to 13 carbon atoms, and the groups of R 3 and R 4 are the same as or different from the groups of R 5 and R 6 .

[0068] In another preferred embodiment of the present invention, R which are identical 3 and R 4 represent an alkyl group containing 6 to 10 carbon atoms, and R which are identical 5 and R 6 represent an alkyl group containing 10 to 15 carbon atoms, and the groups of R 3 and R 4 are different from the groups of R 5 and R 6 .

[0069] In another preferred embodiment of the present invention, R which are identical 3 and R 4 represent an alkyl group containing 10 to 15 carbon atoms, and R which are identical 5 and R 6 represent an alkyl group containing 6 to 10 carbon atoms, and the groups of R 3 and R 4 are different from the groups of R 5 and R 6 .

[0070] In another preferred embodiment of the present invention, R which are identical 3 , R 4 , R 5 and R 6represents an alkyl group containing 5 to 15 carbon atoms, preferably 8 to 13 carbon atoms.

[0071] Advantageously, the Mo-DTC compound has the chemical formula (III), in which: - X 3 and X 4 represent an oxygen atom, - X 5 and X 6 represent a sulfur atom, - R 3 represents an alkyl group containing 8 carbon atoms or an alkyl group containing 13 carbon atoms, - R 4 represents an alkyl group containing 8 carbon atoms or an alkyl group containing 13 carbon atoms, - R 5 represents an alkyl group containing 8 carbon atoms or an alkyl group containing 13 carbon atoms, - R 6 represents an alkyl group containing 8 carbon atoms or an alkyl group containing 13 carbon atoms, and is selected from compounds having the formula.

[0072] Thus, advantageously, the Mo-DTC compound has the chemical formula (III-a):

Chemical formula

[0073] Even more advantageously, the Mo-DTC compound - R 3 , R 4 , R 5 and R 6 represents an Mo-DTC compound having the chemical formula (III-a) in which the alkyl group contains 8 carbon atoms, - R 3 , R4 , R 5 and R 6 A Mo-DTC compound having the chemical formula (III-a) in which R and R each represent an alkyl group containing 13 carbon atoms, and / or - R 3 , R 4 represents an alkyl group containing 8 carbon atoms, and R, R 5 , R 6 A Mo-DTC compound having the chemical formula (III-a) in which each represents an alkyl group containing 13 carbon atoms, is a mixture of.

[0074] Examples of Mo-DTC compounds that may be mentioned include products Molyvan L (registered trademark), Molyvan 807 (registered trademark) or Molyvan 822 (registered trademark) commercially available from R.T Vanderbilt Company (registered trademark), or products Sakura-lube 200 (registered trademark), Sakura-lube 165 (registered trademark), Sakura-lube 525 (registered trademark), Sakura-lube 600 (registered trademark) commercially available from Adeka Corporation.

[0075] The lubricant composition according to the present invention typically contains at least 400 weight ppm of molybdenum element in relation to the total weight of the lubricant composition.

[0076] Preferably, the lubricant composition according to the present invention has a molybdenum element content of 1500 weight ppm or less, more preferably 500 to 1200 ppm, even more preferably 750 to 1000 ppm in relation to the total weight of the lubricant composition.

[0077] [First cleaning additive (magnesium-based)] The lubricant composition according to the present invention also contains at least one first cleaning additive.

[0078] Cleaning additives generally help reduce the formation of deposits on the surface of metal parts by dissolving by-products of oxidation and combustion.

[0079] The cleaning additives that can be used in the lubricant composition according to the present invention are generally known to those skilled in the art. The cleaning additive can be an anionic compound containing a lipophilic hydrocarbon long chain and a hydrophobic head. The associated cation can be a metal cation of an alkali metal or an alkaline earth metal.

[0080] The first cleaning additive is typically selected from carboxylic acids, sulfonates, salicylates, naphthenates, magnesium salts of phenates, and mixtures thereof.

[0081] According to a preferred embodiment, the first cleaning additive is selected from magnesium sulfonates.

[0082] The cleaning agent used becomes non - overbased (or neutral) or overbased. The term "non - overbased" or "neutral" cleaning agent is used when the metal salt contains metal in approximately stoichiometric amounts. The term "overbased cleaning agent" refers to a cleaning agent in which the metal is in excess (an amount greater than the stoichiometric amount). The excess metal that imparts overbased properties to the cleaning agent is in the form of a metal salt insoluble in oil. The overbased cleaning agent thus takes the form of micelles composed of insoluble metal salts kept in suspension in the lubricant composition by the cleaning agent in the form of an oil - soluble metal salt. These micelles can contain one or more types of insoluble metal salts stabilized by one or more types of cleaning agents. When the micelles contain multiple types of cleaning agents that differ from each other with respect to the nature of the hydrophobic chains, the overbased cleaning agent is called a mixed type.

[0083] Advantageously, the one or more first cleaning additives represent 0.5 to 8% by weight, preferably 2 to 4% by weight, in relation to the total weight of the lubricant composition.

[0084] [Second cleaning additive (calcium - based)] According to a preferred embodiment, the composition according to the present invention further comprises at least one second cleaning additive.

[0085] The second cleaning additive is typically selected from among calcium salts.

[0086] Preferably, the second cleaning additive is selected from among calcium salts of carboxylic acids, sulfonates, salicylates, naphthenates, phenates, and mixtures thereof.

[0087] Advantageously, the second cleaning additive is selected from among calcium carboxylates, preferably calcium salicylate.

[0088] The cleaning agent used is either non - overbased (or neutral) or overbased. The term "non - overbased" or "neutral" cleaning agent is used when the metal salt contains the metal in approximately stoichiometric amounts. The term "overbased cleaning agent" refers to a cleaning agent in which the metal is in excess (an amount greater than the stoichiometric amount). The excess metal that imparts overbased properties to the cleaning agent is in the form of a metal salt insoluble in oil. Overbased cleaning agents thus take the form of micelles consisting of insoluble metal salts kept in suspension in the lubricant composition by the cleaning agent in the form of an oil - soluble metal salt. These micelles can contain one or more types of insoluble metal salts stabilized by one or more types of cleaning agents. When the micelles contain multiple types of cleaning agents that differ from each other with respect to the nature of the hydrophobic chains, the overbased cleaning agent is called a mixed type.

[0089] Advantageously, when present, the second cleaning additive represents 0.5 to 8% by weight, preferably 2 to 4% by weight, in relation to the total weight of the lubricant composition.

[0090] According to one embodiment, the composition according to the invention does not contain a second cleaning additive.

[0091] Preferably, according to this embodiment, the content of the magnesium element is at least 1000 ppm by weight, more preferably 1100 - 3000 ppm, even more preferably 1400 - 2800 ppm, and typically 1600 - 2650 ppm, in relation to the total weight of the lubricant composition.

[0092] According to a preferred embodiment, the composition according to the present invention comprises at least one first cleaning additive and at least one second cleaning additive.

[0093] Preferably, according to this preferred embodiment, the total content of magnesium element and calcium element in relation to the total weight of the lubricant composition is at least 1000 ppm by weight, more preferably 1100 - 3000 ppm, even more preferably 1400 - 2800 ppm, and typically 1600 - 2650 ppm.

[0094] For the purposes of the present invention, the term "total content of magnesium element and calcium element" is understood to refer to the sum of the content of magnesium element present in the lubricant composition and the content of calcium element present in the lubricant composition.

[0095] Preferably, the ratio of the calcium element content (derived from the first cleaning additive) to the magnesium element content (derived from the second cleaning additive) is in the range of 10:1 to 1:10.

[0096] Advantageously, the ratio of the calcium element content to the magnesium element content is in the range of 5:1 to 1:5, preferably 5:2 to 2:5, and more preferably 5:2 to 1:1.

[0097] The contribution of the lubricant composition according to the present invention to the BN (base number measured according to ASTM D - 2896) is completely or partially due to neutral or overbased detergents based on alkali metals or alkaline earth metals, particularly the first and second cleaning additives.

[0098] The BN value of the lubricant composition according to the present invention, measured according to ASTM D - 2896, can vary in the range of 1 - 140 mg KOH / g, preferably 3 - 80 mg KOH / g, more preferably 5 - 50 mg KOH / g, and typically 5 - 20 mg KOH / g. The BN value should be selected based on the operating conditions of the lubricant composition and, in particular, the sulfur content of the fuel used.

[0099] [Other additives] In the lubricant composition according to the present invention, many optional additives may also be present.

[0100] Preferred additives for the lubricant composition according to the present invention are cleaning additives other than the first and second cleaning additives defined above, friction regulating additives other than the molybdenum compounds defined above, extreme pressure additives, dispersants, pour point depressants, defoamers, thickeners and mixtures thereof.

[0101] Preferably, the lubricant composition according to the present invention contains one or more extreme pressure additives or mixtures thereof.

[0102] Antiwear additives and extreme pressure additives provide friction protection to the surface by forming a protective film adsorbed on the surface.

[0103] A wide variety of antiwear additives exist. Preferably, for the lubricant composition of the present invention, the antiwear additive is selected from additives containing phosphorus and sulfur, such as metal alkylthiophosphates, specifically zinc alkylthiophosphates and more precisely zinc dialkyldithiophosphates i.e. ZnDTP. A preferred compound is a compound having the formula Zn((SP(S)(OR)(OR’)) 2 wherein R and R’, which may be the same or different, independently represent an alkyl group, preferably an alkyl group containing 1 to 18 carbon atoms.

[0104] Amine phosphates are also antiwear additives that can be used in the lubricant composition of the present invention. However, the phosphorus atoms provided by these additives produce ash and can act as poisons in the automotive catalyst system. These effects can be minimized by replacing a portion of the amine phosphate with additives that do not contribute to phosphorus, such as polysulfides, specifically sulfur-containing olefins.

[0105] Advantageously, the lubricant composition according to the present invention may contain 0.01 to 6% by weight, preferably 0.05 to 4% by weight, more preferably 0.1 to 2% by weight of an antiwear additive and an extreme pressure additive in relation to the total weight of the lubricant composition.

[0106] Advantageously, the lubricant composition according to the present invention contains 0.01 to 6% by weight, preferably 0.05 to 4% by weight, more preferably 0.1 to 2% by weight of an antiwear additive (or antiwear compound) in relation to the total weight of the lubricant composition.

[0107] Advantageously, the composition according to the present invention may contain at least one friction modifier additive in addition to the molybdenum compound of the present invention. The friction modifier additive may specifically be selected from compounds providing a metal element and ashless compounds. Among the compounds providing a metal element, transition metal complexes such as Mo, Sb, Sn, Fe, Cu and Zn can be mentioned, where the ligand can be a hydrocarbon compound containing an oxygen, nitrogen, sulfur or phosphorus atom. Ashless friction modifier additives are generally of organic origin or can be selected from monoesters of fatty acids and polyols, alkoxylated amines, alkoxylated aliphatic amines, aliphatic epoxides, aliphatic epoxide borates, aliphatic amines or glycerol esters. According to the present invention, the aliphatic compound contains at least one hydrocarbon group containing 10 to 24 carbon atoms.

[0108] Advantageously, the lubricant composition according to the present invention may contain 0.01 to 2% by weight or 0.01 to 5% by weight, preferably 0.1 to 1.5% by weight or 0.1 to 2% by weight of a friction modifier additive other than the molybdenum compound according to the present invention in relation to the total weight of the lubricant composition.

[0109] Advantageously, the lubricant composition according to the present invention may contain at least one antioxidant additive.

[0110] Antioxidant additives generally retard the deterioration of the lubricant composition. This deterioration is most often manifested by deposit formation, the presence of sludge, or an increase in the viscosity of the lubricant composition.

[0111] Antioxidants generally act as inhibitors of free radicals or inhibitors that decompose hydroperoxides. Commonly used antioxidants that may be mentioned include phenolic antioxidants, amine antioxidants, and antioxidants containing sulfur and phosphorus. Some of these antioxidants, such as those containing sulfur and phosphorus, can generate ash. Phenolic antioxidant additives can be ash-free or in the form of neutral or basic metal salts. Antioxidant additives specifically can be selected from sterically hindered phenols, esters of sterically hindered phenols, sterically hindered phenols containing thioether linkages, diphenylamines, diphenylamines substituted with at least one C1-C12 alkyl group, N,N'-dialkyl-aryl-diamines, and mixtures thereof.

[0112] Preferably, according to the present invention, the sterically hindered phenol is selected from compounds containing a phenol group in which at least one of the carbon atoms in the vicinity of the carbon atom carrying the alcohol functional group is substituted by at least one C1-C10 alkyl group, preferably a C1-C6 alkyl group, preferably a C4 alkyl group, preferably a tert-butyl group.

[0113] Amine compounds are another class of antioxidant additives that can optionally be used in combination with phenolic antioxidant additives. Examples of amine compounds include aromatic amines, such as aromatic amines having the chemical formula NRaRbRc, where Ra represents an aliphatic group or an optionally substituted aromatic group, Rb represents an optionally substituted aromatic group, Rc represents a hydrogen atom, an alkyl group, an aryl group, or a group having the chemical formula RdS(O) z Re, where Rd represents an alkylene group or an alkenylene group, Re represents an alkyl group, an alkenyl group, or an aryl group, and z represents 0, 1, or 2.

[0114] Sulfur-containing alkylphenols or their alkali metal salts or alkaline earth metal salts can also be used as antioxidant additives.

[0115] Other types of antioxidant additives include copper-containing compounds such as copper thiophosphate or copper dithiophosphate, copper salts and carboxylates, dithiocarbamates, sulfonates, phenates, and copper acetylacetonate. Copper(I) salts and copper(II) salts, as well as succinates or succinic anhydrides, can also be used.

[0116] The lubricant composition according to the present invention can also contain any type of antioxidant known to those skilled in the art.

[0117] Advantageously, the lubricant composition contains at least one ash-free antioxidant additive.

[0118] Also advantageously, the lubricant composition according to the present invention contains at least one antioxidant additive in an amount of 0.1 to 2% by weight based on the total weight of the composition.

[0119] The lubricant composition according to the present invention can also contain at least one detergent additive different from the first and second detergent additives defined above.

[0120] The detergent additive is preferably selected from alkali metal salts or alkaline earth metal salts of carboxylic acids, sulfonates, salicylates, naphthenates, and phenates. The alkali metal and alkaline earth metal are preferably sodium or barium.

[0121] These metal salts generally contain the metal in stoichiometric amounts or in excess, i.e., at a higher content level than the stoichiometric content. Thus, they are overbased detergents at this time, and the excess metal involved in the overbased nature of the detergent additive is generally in the form of an oil-insoluble metal salt, such as a carbonate, hydroxide, oxalate, acetate, glutamate, preferably in the form of a carbonate.

[0122] Advantageously, the lubricant composition according to the invention may comprise, in relation to the total weight of the lubricant composition, 0.2 to 8% by weight or 0.5 to 3% by weight of an additional detergent additive (different from the first and second detergent additives defined above).

[0123] Even more advantageously, the lubricant composition according to the invention may also comprise a pour point depressant additive.

[0124] By retarding the formation of paraffin crystals, the pour point depressant additive generally improves the low temperature behavior of the lubricant composition according to the invention.

[0125] Examples of pour point depressant additives that may be mentioned include alkyl polymethacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes and alkyl polystyrenes.

[0126] Advantageously, the lubricant composition according to the invention may also comprise a dispersant.

[0127] The dispersant may be selected from Mannich bases, succinimides and their derivatives.

[0128] Even more advantageously, the lubricant composition according to the invention may comprise 0.2 to 10% by weight of a dispersant in relation to the total weight of the lubricant composition.

[0129] The lubricant composition according to the invention may also comprise at least one thickener.

[0130] The lubricant composition according to the invention may also comprise an antifoaming agent and a demulsifier.

[0131] [Lubricant composition] Preferably, the lubricant composition, in relation to the total weight of the lubricant composition, - 50 to 95% by weight of at least one base oil, - 0.1 to 13% by weight of at least one viscosity index improver, - At least one organic molybdenum compound with the molybdenum element content in the range of 400 to 1500 ppm by weight, - At least one first cleaning additive selected from magnesium salts of carboxylic acids, sulfonates, salicylates, naphthenates, phenates and mixtures thereof, - Optionally, it contains at least one second cleaning additive selected from calcium salts of carboxylic acids, sulfonates, salicylates, naphthenates, phenates and mixtures thereof, The total content of magnesium element and calcium element in relation to the total weight of the lubricant composition is in the range of 1000 to 3000 ppm by weight.

[0132] Advantageously, the lubricant composition, in relation to the total weight of the lubricant composition, - 60 to 95 wt% of at least one base oil, - 0.5 to 12 wt% of at least one viscosity index improver, - At least one organic molybdenum compound with the molybdenum element content in the range of 500 to 1500 ppm by weight, - At least one first cleaning additive selected from magnesium sulfonate, - Optionally, it contains at least one second cleaning additive selected from calcium salicylate, The total content of magnesium element and calcium element in relation to the total weight of the lubricant composition is in the range of 1400 to 2800 ppm by weight.

[0133] More advantageously, the lubricant composition, in relation to the total weight of the lubricant composition, - 75 to 95 wt% of at least one base oil, - 5 to 10 wt% of at least one viscosity index improver, - At least one organic molybdenum compound with the molybdenum element content in the range of 750 to 100 ppm by weight, - At least one first cleaning additive selected from magnesium sulfonate, - Optionally, it contains at least one second cleaning additive selected from calcium salicylate, In relation to the total weight of the lubricant composition, the total content of magnesium element and calcium element is in the range of 1600 ppm by weight to 2650 ppm by weight.

[0134] [Use and Method] The present invention also relates to the use of the lubricant composition as defined above for lubricating a combustion engine.

[0135] Preferably, the engine is selected from a gasoline engine and a diesel engine, and preferably the combustion engine is a gasoline engine.

[0136] In a preferred embodiment, the engine is the engine of a plug-in hybrid vehicle or a hybrid vehicle having a range extender.

[0137] In the context of the present invention, the term "plug-in hybrid vehicle" refers to a vehicle having an internal combustion engine and an electric motor, and the battery can be charged by the power distribution network. As a result, such a vehicle can be driven in 100% electric mode over a distance of dozens of kilometers, for example 50 kilometers.

[0138] In the context of the present invention, the term "hybrid vehicle having a range extender" is understood to refer to a hybrid vehicle in which only an electric motor drives the wheels. This electric motor is powered by the battery over a distance of dozens of kilometers. When the battery reaches a certain charge threshold (for example, approximately 30%), the internal combustion engine starts and drives the current generator to make it possible to generate the electricity necessary for charging the battery and maintaining the operation of the electric motor.

[0139] According to the first embodiment, the present invention relates to the use of a lubricant composition according to the present invention for preventing, and / or suppressing, and / or mitigating problems related to cold starting of an engine.

[0140] According to the second embodiment, the present invention relates to the use of a lubricant composition according to the present invention for preventing, and / or suppressing, and / or mitigating corrosion phenomena liable to occur in the engine.

[0141] According to the third embodiment, the present invention relates to the use of a lubricant composition according to the present invention for preventing, and / or suppressing, and / or mitigating wear of the engine.

[0142] According to the fourth embodiment, the present invention relates to the use of a lubricant composition according to the present invention for preventing, and / or suppressing, and / or mitigating demixing phenomena of the lubricant composition.

[0143] Within the scope of the gist of the present invention, the term "demixing" is understood to refer to the phenomenon in which water, which is initially present in the lubricant composition in the form of an emulsion, naturally separates from the mixture to form a continuous aqueous phase.

[0144] The ability of the lubricant composition to prevent demixing phenomena can be evaluated, for example, according to the following protocol: 1) Prepare 100 mL of a mixture containing 60 mL of the lubricant composition to be tested, 20 mL of water, and 20 mL of fuel, such as E10 type gasoline. 2) Stir the mixture to make it uniform. 3) Place the mixture in a sealed frustum-shaped flask and then put it in an oven at 60 °C for 18 hours.

[0145] After storing in the oven for 18 hours, the operator visually evaluates the ability of the lubricant composition to prevent demixing.

[0146] When it is found that the mixture is in a single-phase form, this means that the emulsion is stable. In this case, the lubricant composition is given an evaluation of "PASS (qualified)", indicating that the lubricant composition has a very low sensitivity to demixing phenomena.

[0147] Conversely, if the mixture is non-uniform, especially due to the formation of an oily supernatant phase, the lubricant composition is then given an evaluation of "FAIL (unqualified)". The emulsion is not sufficiently stable, and the lubricant composition does not play a sufficient role in preventing demixing phenomena.

[0148] The present invention also relates to a lubrication method for lubricating the engine of a combustion engine, in particular a hybrid vehicle having a plug-in hybrid vehicle or a range extender, the method comprising bringing at least a part of the engine into contact with the lubricant composition according to the present invention.

[0149] Variations and embodiments described in detail below for viscosity index improvers, organomolybdenum compounds, first detergent additives, and second detergent additives are also applicable to the various uses defined above.

[0150] Specific, advantageous or preferred features of the uses combined according to the present invention define specific, advantageous or preferred combinations that can be used according to the present invention.

[0151] The various different aspects of the present invention can be better explained by the following examples.

Mode for Carrying Out the Invention

[0152] [Example 1: Preparation of Lubricant Composition] Lubricant compositions C1, C2, C3 * and C4 * are prepared from the following components: - Base oil 1: The kinematic viscosity at 40 °C measured according to ASTM D445 standard is 19.57 mm 2equal to / s, kinematic viscosity at 100 °C measured according to ASTM D445 standard is 4.23 mm 2 / s, Group III base oil with a viscosity index equal to 122 measured according to ASTM D2270 standard and a NOACK volatility equal to 15% by weight measured according to DIN 51581 standard; - Additive VII: A viscosity index improver which is a conventional olefin polymer; - MoDTC compound: A molybdenum dialkyldithiocarbamate compound commercially available under the product name "Sakuralube 525 (registered trademark)" from Adeka; - PPD: Pour point depressant; - Additive package 1: A conventional additive package containing 5% by weight of a first detergent additive of the magnesium sulfonate type; and 15% by weight of a second detergent additive of the calcium salicylate type. Additive package 1 does not contain any other detergent additives. - Additive package 2: A conventional additive package. Additive package 2 is different from additive package 1 in that it does not contain a magnesium-based detergent additive. In particular, additive package 2 contains only 15% by weight of a calcium salicylate type detergent additive as the only detergent additive. Additive package 2 does not contain any other detergent additives, especially magnesium-based detergent additives. - Additional detergent additive: A conventional detergent additive such as magnesium sulfonate.

[0153] More specifically, compositions C1, C2, C3 * and C4 * are prepared by mixing the compounds listed in Table 2 at a temperature of approximately 60 °C. The percentages shown correspond to weight percentages in relation to the total weight of the composition.

[0154]

Table 2

[0155] Compositions C1 and C2 are according to the present invention.

[0156] Composition C3 * is a comparative composition, containing no organomolybdenum compound.

[0157] Composition C4 * is a comparative composition, containing no magnesium-based cleaning additive.

[0158] [Example 2: Ability to prevent demixing phenomenon] The lubricant compositions prepared as above were evaluated for their ability to prevent the demixing phenomenon according to the following protocol.

[0159] 100 mL of the composition is prepared by mixing 60 mL of the lubricant composition to be tested, 20 mL of water, and 20 mL of E10 type gasoline fuel. The composition is then mixed for 1 minute using an ultraturax (10,000 rpm). The composition is poured into a closed frusto-conical flask and then placed in a 60° C. oven for 18 hours.

[0160] After 18 hours of storage in the oven, the flasks are retrieved and the lubricant compositions are visually evaluated by an operator for their ability to prevent demixing.

[0161] If the mixture is found to be in the form of a single phase, meaning that the emulsion is stable, the lubricant composition is given a "PASS" rating, indicating that the lubricant composition is very low susceptible to the demixing phenomenon.

[0162] Conversely, if the mixture is not homogenous, especially due to the formation of an oily supernatant phase, the lubricant composition is then given a rating of "FAIL." The emulsion is not sufficiently stable and the water phase separates from the oil phase. The lubricant composition does not adequately prevent the demixing phenomenon.

[0163] The results obtained are shown in Table 3.

[0164] [Table 3]

[0165] The compositions C1 and C2 according to the present invention play a role in effectively preventing the demixing phenomenon.

[0166] Conversely, the emulsions obtained from the lubricant compositions C3 * and C4 * are not stable. These latter lubricant compositions thus do not play a role in preventing the demixing phenomenon.

Claims

1. - At least one base oil, - At least one viscosity index improver in an amount of 0.1 to 13% by mass based on the total mass of the lubricant composition, - At least one organic molybdenum compound having a molybdenum element content of at least 400 ppm by mass based on the total mass of the lubricant composition, - At least one first detergent additive selected from magnesium salts of carboxylic acids, sulfonates, salicylates, naphthenates, phenates, and mixtures thereof, - Optionally, at least one second detergent additive selected from calcium salts of carboxylic acids, sulfonates, salicylates, naphthenates, phenates, and mixtures thereof, A lubricant composition comprising: A lubricant composition in which the total content of magnesium element and calcium element based on the total mass of the lubricant composition is at least 1000 ppm by mass.

2. The lubricant composition according to claim 1, wherein the molybdenum element content is 1500 ppm by mass or less based on the total mass of the lubricant composition.

3. The lubricant composition according to claim 1 or 2, wherein the first detergent additive is selected from magnesium sulfonates.

4. The lubricant composition according to any one of claims 1 to 3, comprising at least one second detergent additive selected from calcium salts of carboxylic acids, sulfonates, salicylates, naphthenates, phenates, and mixtures thereof, and the ratio of calcium element content to magnesium element content is in the range of 10:1 to 1:

10.

5. The lubricant composition according to claim 4, wherein the ratio of calcium element content to magnesium element content is in the range of 5:1 to 1:5, preferably 5:2 to 5:2, more preferably 5:2 to 1:

1.

6. The lubricant composition according to any one of claims 1 to 5, wherein the second detergent additive is selected from calcium carboxylates, preferably calcium salicylates.

7. The lubricant composition according to any one of claims 1 to 6, wherein the organic molybdenum compound is selected from molybdenum dithiocarbamate.

8. Use of the lubricant composition according to any one of claims 1 to 7 for lubricating a combustion engine.

9. Use according to claim 8 for lubricating the combustion engine of a plug-in hybrid vehicle or a hybrid vehicle having a range extender.

10. - For preventing, and / or suppressing, and / or mitigating problems associated with cold starting of the engine; and / or - For preventing, and / or suppressing, and / or mitigating corrosion phenomena liable to occur in the engine; and / or - For preventing, and / or suppressing, and / or mitigating wear of the engine; and / or - Use according to claim 8 or 9 for preventing, and / or suppressing, and / or mitigating demixing phenomena of the lubricant composition.

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