Lubricant composition with improved emulsion stability

Abstract

The invention discloses a lubricant composition comprising:-at least one base oil; 0.1% to 13% by weight of at least one viscosity index improver; -at least one organic molybdenum compound, the molybdenum element content being at least 400 ppm by weight; -at least a first detergent additive selected from the group consisting of magnesium salts of carboxylic acids, magnesium salts of sulfonic acids, magnesium salts of salicylic acids, magnesium salts of naphthenic acids, magnesium salts of phenols and any mixture thereof; -optionally, at least a second detergent additive selected from the group consisting of calcium salts of carboxylic acids, calcium salts of sulfonic acids, calcium salts of salicylic acids, calcium salts of naphthenic acids, calcium salts of phenols and any mixture thereof wherein the combined content of elemental magnesium and elemental calcium is at least 1000 ppm by weight relative to the total weight of the lubricant composition.

Description

Technical Field

[0001] The present invention relates to the lubrication of vehicles comprising at least one internal combustion engine. In particular, the present invention relates to the lubrication of hybrid vehicle engines, such as plug-in hybrid vehicles and hybrid vehicles comprising a range extender. Background Art

[0002] A hybrid vehicle consists of two engines, an internal combustion engine and an electric motor. In most hybrid vehicles, the internal combustion engine drives the wheels and is assisted by the electric motor. A battery supplies the electricity needed to run the electric motor; for conventional hybrid vehicles, the battery is recharged 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 technologies are particularly worth mentioning:

[0004] - Micro-hybrid vehicles (also called mild hybrids). These vehicles are equipped with a "stop & start" system to recover energy from braking to charge the battery, which can provide temporary assistance to the internal combustion engine;

[0005] - Mild hybrid vehicles, including electric assistance during acceleration;

[0006] - A full hybrid vehicle is a vehicle that is fully hybridized. At low speeds, when the battery is charged, the electric motor is responsible for both starting and propulsion. At high speeds, or when the battery is discharged, the internal combustion engine takes over, and when more power is needed (for example when accelerating), both engines work together. Thus, it is possible to travel several kilometers with the internal combustion engine turned off.

[0007] Other complementary technologies have been developed recently: plug-in hybrid vehicles and hybrid vehicles with range extenders. So-called plug-in hybrid vehicles include an internal combustion engine and an electric motor, wherein the battery can be charged on the power grid; thus, these vehicles can travel in 100% electric mode for distances of several tens of kilometers, for example 50 kilometers. In hybrid vehicles with an auxiliary power unit (called a "range extender"), only the electric motor drives the wheels. Such an electric motor is powered by the battery over a distance of several tens of kilometers. When the battery reaches a certain threshold level of charge (for example, about 30%), the internal combustion engine starts and drives the current generator, making it possible to generate the electricity required to charge the battery and keep the electric motor running.

[0008] Lubricant compositions, especially those used for lubrication of internal combustion engines, usually include small amounts of water, mainly due to the direct adsorption of water contained in the air by the lubricant or even water generated by condensation of ambient water vapor. Lubricant compositions usually contain 0% to 10% of water. Although present in trace amounts, water in lubricant compositions is the cause of problems such as cold starting, corrosion and premature wear of internal combustion engines. Therefore, in order to prevent these phenomena, it is necessary to keep this water in the form of an emulsion.

[0009] However, in hybrid vehicle engines, particularly plug-in hybrids or those that include a range extender, the low frequency of use of the internal combustion engine is particularly susceptible to problems associated with stratification of the lubricant composition. When the lubricant composition is left at rest, the emulsion becomes unstable and the water separates from the oil phase, forming a continuous phase.

[0010] Similar problems are also observed in conventional vehicles (especially gasoline engines) that are only equipped with an internal combustion engine (non-hybrid vehicles) and are run occasionally. Since the lubricant composition does not circulate regularly in the engine, the water present tends to separate from the rest of the lubricant composition and form a continuous phase.

[0011] Therefore, there is a need to provide a specific lubricant composition that can effectively lubricate such engine systems while preventing stratification problems. Summary of the invention

[0012] An object of the present invention is to provide a lubricant composition capable of effectively lubricating an internal combustion engine, in particular an engine of a plug-in hybrid vehicle or a vehicle including a range extender.

[0013] Another object of the present invention is to provide a lubricant composition having improved emulsion stability. In particular, the present invention aims to provide a lubricant composition which can maintain water in the form of a stable emulsion.

[0014] These objects are achieved by the lubricant composition of the present invention, comprising:

[0015] - at least one base oil;

[0016] - 0.1% to 13% by weight of at least one viscosity index improver additive, relative to the total weight of the lubricant composition;

[0017] at least one organic molybdenum compound, wherein the content of molybdenum element is at least 400 ppm by weight relative to the total weight of the lubricant composition;

[0018] - at least a first detergent additive selected from magnesium salts of carboxylic acids, magnesium salts of sulfonic acids, magnesium salts of salicylates, magnesium salts of naphthenic acids, magnesium salts of phenols and any mixtures thereof;

[0019] - Optionally, at least a second detergent additive selected from calcium salts of carboxylic acids, calcium salts of sulfonic acids, calcium salts of salicylates, calcium salts of naphthenic acids, calcium salts of phenols and any mixtures thereof;

[0020] Wherein, the combined content of magnesium and calcium is at least 1000 ppm by weight relative to the total weight of the lubricant composition. DETAILED DESCRIPTION

[0021] Base oil

[0022] The base oil used in the lubricant composition according to the invention may be an oil of mineral or synthetic origin (Table A) or a mixture thereof, belonging to groups I to V of the categories defined according to the American Petroleum Institute (API) classification (or its equivalent according to the ATIEL [European Technical Association of the Lubricant Industry] classification).

[0023] Table 1

[0024]

[0025] Mineral base oils according to the 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.

[0026] Mixtures of synthetic and mineral oils may also be used, possibly regenerated.

[0027] Generally, there are no restrictions on the use of different lubricant base oils for producing the lubricant composition according to the invention, except that they must have suitable properties for use in vehicle engines or transmissions, especially with regard to viscosity, viscosity index, sulfur content and antioxidant properties.

[0028] The base oil of the lubricant composition according to the invention may also be chosen from synthetic oils, such as esters of certain carboxylic acids and alcohols, and from polyalphaolefins. The polyalphaolefins used as base oils are obtained, for example, from monomers containing 4 to 32 carbon atoms, such as octene or decene, and have a viscosity of 1.5 mm at 100° C. according to standard ASTM D445. 2 ·s -1 Up to 15mm 2 ·s -1 Their average molecular weight, according to standard ASTM D5296, is generally between 250 and 3,000.

[0029] The lubricant composition according to the invention may comprise at least 50% by weight of base oil relative to the total weight of the composition. In a more advantageous manner, the lubricant composition according to the invention comprises at least 60% by weight, or indeed at least 70% by weight, of base oil relative to the total weight of the composition. In a particularly more advantageous manner, the lubricant composition according to the invention comprises from 75% to 95% by weight of base oil relative to the total weight of the composition.

[0030] Viscosity Index Improver Additives

[0031] The lubricant composition according to the present invention comprises at least one viscosity index improver for improving the viscosity index of the lubricant composition.

[0032] For the purposes of the present invention, the term "viscosity index improver" is understood to mean a compound used to ensure that the lubricant composition has good cold flow properties and minimum viscosity at high temperatures.

[0033] As examples of viscosity index improver polymers, mention may be made of polymer esters; hydrogenated or non-hydrogenated homopolymers or copolymers of styrene, butadiene and isoprene; homopolymers or copolymers of olefins (eg, ethylene or propylene); and polyacrylates and polymethacrylates (PMA).

[0034] The lubricant composition according to the invention generally comprises 0.1 to 13 wt. % of viscosity index improver, relative to the total weight of the lubricant composition.

[0035] Preferably, the lubricant composition according to the invention comprises 0.5 to 12 wt. % of viscosity index improver, more preferably 1 to 10 wt. %, still more preferably 5 to 10 wt. %, relative to the total weight of the lubricant composition.

[0036] Organic molybdenum compounds

[0037] The lubricant composition according to the invention comprises at least one organic molybdenum compound.

[0038] The term "organomolybdenum compound" according to the present invention is understood to mean any fat-soluble (lipid-soluble) organomolybdenum compound.

[0039] The organic molybdenum compound according to the present invention can be selected from organic molybdenum complexes, which contain at least one chemical element molybdenum (Mo), preferably at least two chemical elements molybdenum (Mo), and at least one ligand, such as a carboxylate ligand, an ester ligand, an amide ligand, a dithiophosphate ligand or a dithiocarbamate ligand.

[0040] For example, organic complexes of molybdenum with carboxylates, esters and amides can be obtained by reacting molybdenum oxide or ammonium molybdate with fatty substances, glycerides, fatty acids or fatty acid derivatives (esters, amines, amides, etc.).

[0041] For the purposes of the present invention, carboxylic acid ligands, ester ligands, and amide ligands are free of sulfur and phosphorus.

[0042] In one embodiment, the organic molybdenum compound of the present invention is selected from a complex of molybdenum with an amide ligand, which is mainly prepared by reacting a molybdenum source (for example, molybdenum trioxide) with an amine derivative and a fatty acid containing, for example, 4 to 36 carbon atoms (for example, a fatty acid contained in a plant or animal oil).

[0043] The synthesis of such compounds is described, for example, in patents US4889647, EP0546357, US5412130 or EP1770153.

[0044] According to a preferred embodiment, the organomolybdenum compound is selected from binuclear organomolybdenum compounds. For the purposes of the present invention, the term "binuclear organomolybdenum compound" is understood to mean an organomolybdenum compound whose core contains two molybdenum atoms. They are also called dimeric organomolybdenum compounds.

[0045] In a preferred embodiment of the present invention, the organic molybdenum compound is selected from an organic complex of molybdenum and an amide ligand obtained by the following reaction:

[0046] (i) fatty substances of the following types: mono-, di- or tri-glycerides or fatty acids;

[0047] (ii) an amino source having the formula (A):

[0048]

[0049] in:

[0050] -X 1 represents an oxygen atom or a nitrogen atom;

[0051] -X 2 represents an oxygen atom or a nitrogen atom;

[0052] -When X 1 or X 2 When they represent oxygen atoms, n or m represents 1;

[0053] -When X 1 or X 2 When they represent nitrogen atoms, n or m represents 2;

[0054] (iii) and a molybdenum source selected from molybdenum trioxide or a molybdate, preferably ammonium molybdate.

[0055] In one embodiment of the present invention, the organic molybdenum compound may contain 0.1-30 wt %, preferably 0.1-20 wt %, more preferably 2-8.5 wt % of molybdenum, relative to the total weight of the organic molybdenum complex.

[0056] Preferably, the organomolybdenum compound comprises at least one organomolybdenum complex having the formula (I) or (II), alone or in the form of a mixture:

[0057]

[0058] in:

[0059] -X 1 represents an oxygen atom or a nitrogen atom;

[0060] -X 2 represents an oxygen atom or a nitrogen atom;

[0061] -When X 1 When X represents an oxygen atom, n represents 1, and when X 2 When it represents an oxygen atom, m represents 1;

[0062] -When X 1 When X represents a nitrogen atom, n represents 2, and when X 2 When it represents a nitrogen atom, m represents 2;

[0063] R1 represents a linear or branched, saturated or unsaturated alkyl group containing 4 to 36 carbon atoms, preferably 4 to 20 carbon atoms, advantageously 6 to 18 carbon atoms;

[0064]

[0065] in:

[0066] -X 1 represents an oxygen atom or a nitrogen atom;

[0067] -X 2 represents an oxygen atom or a nitrogen atom;

[0068] -When X 1 When X represents an oxygen atom, n represents 1, and when X 2 When it represents an oxygen atom, m represents 1;

[0069] -When X 1 When X represents a nitrogen atom, n represents 2, and when X 2 When it represents a nitrogen atom, m represents 2;

[0070] - R1 represents a linear or branched, saturated or unsaturated alkyl group containing 4 to 36 carbon atoms, preferably 4 to 20 carbon atoms, advantageously 6 to 18 carbon atoms;

[0071] - R2 represents a linear or branched, saturated or unsaturated alkyl group containing 4 to 36 carbon atoms, preferably 4 to 20 carbon atoms, advantageously 6 to 18 carbon atoms.

[0072] Advantageously, the organic complex of molybdenum having formula (I) or (II) is prepared by the following reaction:

[0073] (i) fatty substances of the following types: mono-, di- or tri-glycerides or fatty acids;

[0074] (ii) diethanolamine or 2-(2-aminoethyl)aminoethanol;

[0075] (iii) and a molybdenum source selected from molybdenum trioxide or a molybdate, preferably ammonium molybdate.

[0076] More advantageously, the organic complex of molybdenum of formula (I) is composed of at least one compound of formula (Ia) or (Ib), alone or in a mixture:

[0077]

[0078] wherein R1 represents a linear or branched, saturated or unsaturated alkyl group containing 4 to 36 carbon atoms, preferably 4 to 20 carbon atoms, advantageously 6 to 18 carbon atoms,

[0079]

[0080] Therein, R1 represents a linear or branched, saturated or unsaturated alkyl group containing 4 to 36 carbon atoms, preferably 4 to 20 carbon atoms, advantageously 6 to 18 carbon atoms.

[0081] As an example of a sulfur-free molybdenum complex according to the invention, mention may be made of Molyvan® sold by the company Vanderbilt.

[0082] In another embodiment of the present invention, the organic molybdenum compound is selected from organic complexes of molybdenum with dithiophosphate ligands or organic complexes of molybdenum with dithiocarbamate ligands. Within the meaning of the present invention, organic complexes of molybdenum with dithiophosphate ligands are also referred to as molybdenum dithiophosphates or Mo-DTP compounds, and organic complexes of molybdenum with dithiocarbamate ligands are also referred to as molybdenum dithiocarbamates or Mo-DTC compounds.

[0083] In a more preferred embodiment of the present invention, the organo-molybdenum compound is selected from molybdenum dithiocarbamates. Mo-DTC compounds are complexes formed by a molybdenum metal core connected to one or more ligands, the ligands being alkyl dithiocarbamate groups. These compounds are well known to those skilled in the art.

[0084] In one embodiment of the present invention, the Mo-DTC compound may contain 1-40 wt%, preferably 2-30 wt%, more preferably 3-28 wt%, advantageously 4-15 wt% of molybdenum relative to the total weight of the Mo-DTC compound.

[0085] In another embodiment of the present invention, the Mo-DTC compound may contain 1-40 wt%, preferably 2-30 wt%, more preferably 3-28 wt%, advantageously 4-15 wt% of sulfur relative to the total weight of the Mo-DTC compound.

[0086] In a preferred embodiment of the present invention, the Mo-DTC compound is a dimeric Mo-DTC compound. Examples of dimeric Mo-DTC compounds that may be mentioned include the compounds described in documents EP 0757093, EP 0719851, EP 0743354 or EP 1013749 and the related preparation methods.

[0087] The dimeric Mo-DTC compounds generally correspond to compounds having formula (III):

[0088]

[0089] in:

[0090] R3, R4, R5, and R6 may be the same or different and independently represent a hydrocarbon group selected from an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, or a cycloalkenyl group;

[0091] X3, X4, X5 and X6 may be the same or different and independently represent an oxygen atom or a sulfur atom.

[0092] The term "alkyl" within the meaning of the present invention is understood to mean a straight-chain or branched, saturated or unsaturated hydrocarbon radical containing 1 to 24 carbon atoms, preferably 4 to 18 carbon atoms. In one embodiment of the present invention, the alkyl radical 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, eicosyl, 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.

[0093] The term "alkenyl" is understood within the meaning of the present invention to mean a straight or branched hydrocarbon radical comprising at least one double bond and containing from 2 to 24 carbon atoms. The alkenyl radical may be selected from vinyl, allyl, propenyl, butenyl, isobutenyl, pentenyl, isopentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl and oleic.

[0094] The term "aryl" is understood within the meaning of the present invention to refer to polycyclic aromatic hydrocarbons or aromatic groups, whether or not substituted by alkyl. The aryl group may contain 6 to 24 carbon atoms. In one embodiment, the aryl group may be selected from the group consisting of phenyl, tolyl, xylyl, cumyl, mesityl, benzyl, phenethyl, styryl, cinnamyl, diphenylmethyl, triphenylmethyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, nonylphenyl, decylphenyl, undecylphenyl, dodecylphenyl, phenylphenyl, benzylphenyl, phenyl-styrene, p-cumylphenyl and naphthyl.

[0095] The term "cycloalkyl" is understood within the meaning of the present invention to mean a cyclic or polycyclic hydrocarbon, whether or not substituted by an alkyl group. The term 'cycloalkenyl' is understood within the meaning of the present invention to mean a cyclic or polycyclic hydrocarbon, whether or not substituted by an alkyl group, and containing at least one degree of unsaturation. Cycloalkyl and cycloalkenyl groups may contain from 3 to 24 carbon atoms.

[0096] For the purposes of the present invention, cycloalkyl and cycloalkenyl groups may be selected from, but are not limited to, the group consisting of cyclopentyl, cyclohexyl, cycloheptyl, methylcyclopentyl, methylcyclohexyl, methylcycloheptyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, methylcyclopentenyl, methylcyclohexenyl.

[0097] In a preferred embodiment of the present invention, R3, R4, R5 and R6 may be the same or different and 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.

[0098] In one embodiment of the present invention, X3, X4, X5 and X6 may be the same and may represent a sulfur atom.

[0099] In another embodiment of the present invention, X3, X4, X5 and X6 may be the same and may be oxygen atoms.

[0100] In another embodiment of the present invention, X3 and X4 may represent sulfur atoms, and X5 and X6 may represent oxygen atoms.

[0101] In another embodiment of the present invention, X3 and X4 may represent oxygen atoms, and X5 and X6 may represent sulfur atoms.

[0102] In another embodiment of the present invention, the ratio of the number of sulfur atoms to the number of oxygen atoms (S / O) in the Mo-DTC compound may vary from (1 / 3) to (3 / 1).

[0103] In another embodiment of the present invention, the Mo-DTC compound having the formula (III) may be selected from symmetric Mo-DTC compounds, asymmetric Mo-DTC compounds, and combinations thereof.

[0104] The term "symmetrical Mo-DTC compounds" according to the present invention is understood to mean Mo-DTC compounds of formula (V) in which the radicals R3, R4, R5 and R6 are identical.

[0105] The term "asymmetric Mo-DTC compounds" according to the present invention is understood to mean Mo-DTC compounds of formula (V) wherein the R3 and R4 groups are identical, the R5 and R6 groups are identical, and the R3 and R4 groups are different from the R5 and R6 groups.

[0106] In a preferred embodiment of the present invention, the Mo-DTC compound is a mixture of at least one symmetrical Mo-DTC compound and at least one asymmetrical Mo-DTC compound.

[0107] In one embodiment of the present invention, the same R3 and R4 represent an alkyl group containing 5-15 carbon atoms, preferably 8-13 carbon atoms; R5 and R6 are the same, representing an alkyl group containing 5-15 carbon atoms, preferably 8-13 carbon atoms; and the R3 and R4 groups are the same or different from the R5 and R6 groups.

[0108] In another preferred embodiment of the present invention, R3 and R4 are the same, representing an alkyl group containing 6-10 carbon atoms; R5 and R6 are the same, representing an alkyl group containing 10-15 carbon atoms; and R3 and R4 groups are different from R5 and R6 groups.

[0109] In another preferred embodiment of the present invention, R3 and R4 are the same, representing an alkyl group containing 10-15 carbon atoms; R5 and R6 are the same, representing an alkyl group containing 6-10 carbon atoms; and R3 and R4 groups are different from R5 and R6 groups.

[0110] In another preferred embodiment of the present invention, R3, R4, R5 and R6 are the same and represent an alkyl group containing 5 to 15 carbon atoms, preferably 8 to 13 carbon atoms.

[0111] In an advantageous manner, the Mo-DTC compound is selected from compounds of formula (III) in which:

[0112] -X3 and X4 represent oxygen atoms;

[0113] -X5 and X6 represent sulfur atoms;

[0114] - R3 represents an alkyl group containing 8 carbon atoms or an alkyl group containing 13 carbon atoms;

[0115] - R4 represents an alkyl group containing 8 carbon atoms or an alkyl group containing 13 carbon atoms;

[0116] - R5 represents an alkyl group containing 8 carbon atoms or an alkyl group containing 13 carbon atoms;

[0117] -R6 represents an alkyl group containing 8 carbon atoms or an alkyl group containing 13 carbon atoms.

[0118] Thus, in an advantageous manner, the Mo-DTC compound is selected from compounds having formula (III-a)

[0119]

[0120] Wherein, the groups R3, R4, R5 and R6 are defined as in formula (III).

[0121] In a more advantageous manner, the Mo-DTC compound is a mixture of:

[0122] - Mo-DTC compounds of formula (III-a), wherein R3, R4, R5 and R6 represent an alkyl group containing 8 carbon atoms;

[0123] - a Mo-DTC compound of formula (III-a) in which R3, R4, R5 and R6 represent an alkyl group containing 13 carbon atoms; and / or

[0124] - A Mo-DTC compound having the formula (III-a), wherein R3, R4 represent an alkyl group containing 8 carbon atoms; and R5 and R6 represent an alkyl group containing 13 carbon atoms.

[0125] Examples of Mo-DTC compounds that may be mentioned include those prepared by RT Vanderbilt Products sold by Molyvan Molyvan or Molyvan Or the product Sakura-lube sold by Adeka Sakura-lube Sakura-lube or Sakura-lube

[0126] The lubricant composition according to the invention generally comprises at least 400 ppm by weight of elemental molybdenum, relative to the total weight of the lubricant composition.

[0127] Preferably, the lubricant composition according to the present invention has a molybdenum content of less than or equal to 1,500 ppm by weight, more preferably 500 ppm to 1200 ppm, and even more preferably 750 ppm to 1000 ppm, relative to the total weight of the lubricant composition.

[0128] The first detergent additive (magnesium based)

[0129] The lubricant composition according to the invention also comprises at least one first detergent additive.

[0130] Detergent additives are typically used to reduce the formation of deposits on the surfaces of metal parts by dissolving the by-products of oxidation and combustion.

[0131] Detergent additives that can be used in the lubricant composition according to the present invention are well known to those skilled in the art. The detergent additive can be an anionic compound comprising a long lipophilic hydrocarbon chain and a hydrophobic head. The associated cation can be a metal cation of an alkali metal or an alkaline earth metal.

[0132] The first detergent additive is typically selected from the group consisting of magnesium salts of carboxylic acids, magnesium salts of sulfonic acids, magnesium salts of salicylic acids, magnesium salts of naphthenic acids, magnesium salts of phenols, and any mixtures thereof.

[0133] According to a preferred embodiment, the first detergent additive is selected from the group consisting of magnesium sulfonates.

[0134] The detergent used will be non-high alkalinity (or neutral) or high alkalinity. When the metal salt contains an approximately stoichiometric amount of metal, the term non-high alkalinity or neutral detergent is used. The term "high alkalinity detergent" refers to a detergent in which the metal is excessive (the amount is greater than the stoichiometric amount). The excess metal that makes the detergent have a high alkalinity property exists in the form of a metal salt that is insoluble in oil. Therefore, the high alkalinity detergent adopts a micellar form composed of insoluble metal salts, and the insoluble metal salts are kept suspended in the lubricant composition by a detergent in the form of an oil-soluble metal salt. These micelles may contain one or more types of insoluble metal salts, which are stabilized by one or more types of detergents. If the micelle contains several types of detergents, the properties of the hydrophobic chains of these detergents are different from each other, then the high alkalinity detergent is referred to as a mixed type.

[0135] Advantageously, the one or more first detergent additives represent from 0.5% to 8% by weight, preferably from 2% to 4% by weight, relative to the total weight of the lubricant composition.

[0136] Second detergent additive (calcium based)

[0137] According to a preferred embodiment, the composition according to the invention also comprises at least one second detergent additive.

[0138] The second detergent additive is typically selected from calcium salts.

[0139] Preferably, the second detergent additive is selected from calcium salts of carboxylic acids, calcium salts of sulfonic acids, calcium salts of salicylic acids, calcium salts of cyclohexane acids, calcium salts of phenols, and any mixtures thereof.

[0140] Advantageously, the second detergent additive is selected from calcium carboxylates, preferably calcium salicylates.

[0141] The detergent used will be non-high alkalinity (or neutral) or high alkalinity. When the metal salt contains an approximately stoichiometric amount of metal, the term "non-high alkalinity" or "neutral" detergent is used. The term "high alkalinity detergent" refers to a detergent in which the metal is excessive (the amount is greater than the stoichiometric amount). The excess metal that makes the detergent have a high alkalinity property exists in the form of a metal salt that is insoluble in oil. Therefore, the high alkalinity detergent adopts a micellar form composed of insoluble metal salts, and the insoluble metal salts are kept suspended in the lubricant composition by a detergent in the form of an oil-soluble metal salt. These micelles may contain one or more types of insoluble metal salts, which are stabilized by one or more types of detergents. If the micelle contains several types of detergents, the properties of the hydrophobic chains of these detergents are different from each other, then the high alkalinity detergent is called a mixed type.

[0142] Advantageously, when present, the second detergent additive is from 0.5% to 8% by weight, preferably from 2% to 4% by weight relative to the total weight of the lubricant composition.

[0143] According to one embodiment, the composition according to the invention is free of a secondary detergent additive.

[0144] Preferably, according to this embodiment, the content of magnesium element is at least 1000 ppm by weight, more preferably 1100 to 3000 ppm, even more preferably 1400 to 2800 ppm, typically 1600 to 2650 ppm, relative to the total weight of the lubricant composition.

[0145] According to a preferred embodiment, the composition according to the invention comprises at least one first detergent additive and at least one second detergent additive.

[0146] Preferably, according to this preferred embodiment, the combined content of magnesium and calcium elements is at least 1000 ppm by weight, more preferably 1100 ppm-3000 ppm, even more preferably 1400 ppm-2800 ppm, typically 1600 ppm-2650 ppm, relative to the total weight of the lubricant composition.

[0147] For the purposes of the present invention, the term "combined content of magnesium and calcium" is understood to mean the sum of the content of magnesium present in the lubricant composition and the content of calcium present in the lubricant composition.

[0148] Preferably, the ratio of the calcium content (from the first detergent additive) to the magnesium content (from the second detergent additive) is 10:1 to 1:10.

[0149] Advantageously, the ratio of calcium content to magnesium content is 5:1 to 1:5, preferably 5:2 to 5:2, and more preferably 5:2 to 1:1.

[0150] The contribution of the BN (Base Number measured according to ASTM D-2896) of the lubricant composition according to the invention is due in whole or in part to the neutral or overbased detergent based on alkali metals or alkaline earth metals, in particular the first detergent additive and the second detergent additive.

[0151] The BN value of the lubricant composition according to the present invention measured according to ASTM D-2896 may be 1 to 140 mg KOH / g, preferably 3 to 80 mg KOH / g, more preferably 5 to 50 mg KOH / g, typically 5 to 20 mg KOH / g. The BN value should be selected according to the use conditions of the lubricant composition, in particular the sulfur content of the fuel used.

[0152] Other additives

[0153] A number of optional additives may also be present in the lubricant compositions of the present invention.

[0154] Preferred additives for the lubricant composition according to the invention are selected from detergent additives other than the first detergent additive and the second detergent additive defined above, friction modifier additives other than the molybdenum compounds defined above, extreme pressure additives, dispersants, pour point activators, defoamers, thickeners and mixtures thereof.

[0155] Preferably, the lubricant composition according to the invention comprises one or more extreme pressure additives or mixtures thereof.

[0156] Anti-wear additives and extreme pressure additives provide friction protection to surfaces by forming protective films that adsorb onto these surfaces.

[0157] There are many anti-wear additives. Preferably, for the lubricant composition of the present invention, the anti-wear additive is selected from additives containing phosphorus and sulfur, such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, and more precisely zinc dialkyldithiophosphates or ZnDTP. Preferred compounds are compounds of the formula Zn((SP(S)(OR)(OR'))2, wherein R and R' may be the same or different and independently represent an alkyl group, preferably an alkyl group containing 1 to 18 carbon atoms.

[0158] Amine phosphates are also anti-wear additives that can be used in the lubricant compositions of the present invention. However, the phosphorus atoms provided by these additives can act as poisons for automotive catalytic systems because they produce ash. These effects can be minimized by replacing a portion of the amine phosphates with additives that do not produce phosphorus (e.g., polysulfides, particularly sulfur-containing olefins).

[0159] Advantageously, the lubricant composition according to the invention may comprise 0.01-6 wt. %, preferably 0.05-4 wt. %, more preferably 0.1-2 wt. % of antiwear additives and extreme pressure additives relative to the total weight of the lubricant composition.

[0160] Advantageously, the lubricant composition according to the invention comprises 0.01-6% by weight, preferably 0.05-4% by weight, more preferably 0.1-2% by weight of antiwear additives (or antiwear compounds), relative to the total weight of the lubricant composition.

[0161] Advantageously, the composition according to the invention may comprise at least one friction modifier additive different from the molybdenum compound of the invention. The friction modifier additive may be chosen in particular from compounds providing metal elements and ashless compounds. Among the compounds providing metal elements, mention may be made of transition metal complexes, such as Mo, Sb, Sn, Fe, Cu and Zn, in which the ligand may be a hydrocarbon compound containing oxygen, nitrogen, sulfur or phosphorus atoms. Ashless friction modifier additives are generally of organic origin or may be chosen from monoesters of fatty acids and polyols, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, fatty epoxide borates, fatty amines or glycerides. According to the invention, the aliphatic compound comprises at least one hydrocarbon radical comprising 10 to 24 carbon atoms.

[0162] Advantageously, the lubricant composition according to the invention may comprise 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, relative to the total weight of the lubricant composition, of friction modifier additives other than the molybdenum compound according to the invention.

[0163] Advantageously, the lubricant composition according to the invention may comprise at least one antioxidant additive.

[0164] Antioxidant additives generally retard the degradation of lubricant compositions. Such degradation is most often manifested by the formation of deposits, the presence of sludge, or an increase in the viscosity of the lubricant composition.

[0165] Antioxidant additives usually act as free radical inhibitors or inhibitors for decomposing hydroperoxides. Common antioxidants that may be mentioned include phenolic antioxidants, amine antioxidants, sulfur- and phosphorus-containing antioxidants. Some antioxidants, such as sulfur- and phosphorus-containing antioxidants, can produce ash. Phenolic antioxidant additives can be ashless, or in the form of neutral or alkaline metal salts. Antioxidant additives can especially be selected from hindered phenols, esters of hindered phenols, hindered phenols containing thioether bridges, diphenylamines, diphenylamines substituted with at least one C1-C12 alkyl, N, N'-dialkyl-aryl-diamines and mixtures thereof.

[0166] Preferably, according to the invention, the hindered phenol is chosen from compounds comprising a phenolic group, wherein at least one carbon atom near the carbon atom carrying the alcohol function is substituted by at least one C1-C10 alkyl group, preferably C1-C6 alkyl group, preferably C4 alkyl group, preferably tert-butyl group.

[0167] Amine compounds are another class of antioxidant additives that can be used in combination with phenolic antioxidant additives. Examples of amine compounds include aromatic amines, such as aromatic amines having the formula NRaRbRc, wherein Ra represents an optionally substituted aliphatic group or an 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 formula RdS(O)zRe, wherein 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.

[0168] Sulfur-containing alkylphenols or alkali metal or alkaline earth metal salts thereof may also be used as antioxidant additives.

[0169] Other classes of antioxidant additives include copper-containing compounds such as copper thio- or dithiophosphates; copper salts and carboxylates; dithiocarbamates; sulfonates; phenates; copper acetylacetonate. Salts of succinic acid or succinic anhydride and copper I and copper II salts may also be used.

[0170] The lubricant composition according to the invention may also comprise any type of antioxidant known to a person skilled in the art.

[0171] Advantageously, the lubricant composition comprises at least one ashless antioxidant additive.

[0172] Advantageously also, the lubricant composition according to the invention comprises from 0.1% to 2% by weight of at least one antioxidant additive, relative to the total weight of the composition.

[0173] The lubricant composition according to the invention may further comprise at least one detergent additive which is different from the first detergent additive and the second detergent additive defined above.

[0174] The detergent additive is preferably selected from alkali metal 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.

[0175] These metal salts usually contain the metal in a stoichiometric amount or in excess, that is, at a level greater than the stoichiometric content. These latter are therefore overbased detergents; the excess metal associated with the overbased nature of the detergent additive is usually in the form of an oil-insoluble metal salt, such as a carbonate, hydroxide, oxalate, acetate, glutamate, preferably a carbonate.

[0176] Advantageously, the lubricant composition according to the invention may comprise 0.2% to 8% or 0.5% to 3% by weight of additional detergent additive (other than the first and second detergent additives defined above), relative to the total weight of the lubricant composition.

[0177] Likewise, in an advantageous manner, the lubricant composition according to the invention may also comprise a pour point depressant additive. Pour point depressant additives generally improve the low temperature properties of the lubricant composition according to the invention by slowing down the formation of paraffin crystals. Examples of pour point depressant additives that may be mentioned include alkyl polymethacrylates, polyacrylates, polyaromatic amides, polyalkylphenols, polyalkylnaphthalenes and alkyl polystyrenes.

[0178] Advantageously, the lubricant composition according to the invention may also contain a dispersant. The dispersant may be selected from Mannich bases, succinimide and derivatives thereof. Likewise, in an advantageous manner, the lubricant composition according to the invention may contain 0.2% to 10% by weight of a dispersant relative to the total weight of the lubricant composition.

[0179] The lubricant composition according to the invention may also comprise at least one thickener.

[0180] The lubricant composition according to the invention may also contain defoamers and demulsifiers.

[0181] Lubricant composition

[0182] Preferably, relative to the total weight of the lubricant composition, the lubricant composition comprises:

[0183] - 50% to 95% by weight of at least one base oil;

[0184] - 0.1% to 13% by weight of at least one viscosity index improver additive;

[0185] - at least one organic molybdenum compound, wherein the molybdenum content is 400 ppm to 1500 ppm by weight;

[0186] - at least a first detergent additive selected from magnesium salts of carboxylic acids, magnesium salts of sulfonic acids, magnesium salts of salicylates, magnesium salts of naphthenic acids, magnesium salts of phenols and any mixtures thereof;

[0187] - optionally, at least a second detergent additive selected from calcium salts of carboxylic acids, calcium salts of sulfonic acids, calcium salts of salicylates, calcium salts of naphthenic acids, calcium salts of phenols and any mixtures thereof,

[0188] Wherein, the combined content of magnesium and calcium is 1000 ppm to 3000 ppm by weight relative to the total weight of the lubricant composition.

[0189] Advantageously, the lubricant composition comprises, relative to the total weight of the lubricant composition:

[0190] - 60% to 95% by weight of at least one base oil;

[0191] - 0.5% to 12% by weight of at least one viscosity index improver additive;

[0192] - at least one organic molybdenum compound, wherein the molybdenum content is 500 ppm to 1500 ppm by weight;

[0193] - at least a first detergent additive selected from the group consisting of magnesium sulfonates;

[0194] - optionally, at least a second detergent additive selected from the group consisting of calcium salicylates,

[0195] Wherein, the combined content of magnesium and calcium is 1400 ppm to 2800 ppm by weight relative to the total weight of the lubricant composition.

[0196] In a more advantageous manner, the lubricant composition comprises, relative to the total weight of the lubricant composition:

[0197] - 75% to 95% by weight of at least one base oil;

[0198] - 5% to 10% by weight of at least one viscosity index improver additive;

[0199] - at least one organic molybdenum compound, wherein the molybdenum content is 750 ppm to 100 ppm by weight;

[0200] - at least a first detergent additive selected from the group consisting of magnesium sulfonates;

[0201] - optionally, at least a second detergent additive selected from the group consisting of calcium salicylates,

[0202] Wherein, the combined content of magnesium and calcium is 1600 ppm to 2650 ppm by weight relative to the total weight of the lubricant composition.

[0203] Uses and methods

[0204] The invention also relates to the use of a lubricant composition as described above for the lubrication of an internal combustion engine.

[0205] Preferably, the engine is selected from a gasoline engine and a diesel engine, preferably, the internal combustion engine is a gasoline engine.

[0206] In a preferred embodiment, the engine is an engine of a plug-in hybrid vehicle or a hybrid vehicle with a range extender.

[0207] In the context of the present invention, the term "plug-in hybrid vehicle" is understood to mean a vehicle comprising an internal combustion engine and an electric motor, wherein the battery can be charged on the grid; such a vehicle can therefore travel in 100% electric mode for distances of several tens of kilometers, for example 50 kilometers.

[0208] In the context of the present invention, the term "hybrid vehicle with range extender" is understood to mean a hybrid vehicle in which only the electric motor drives the wheels. This electric motor is powered by the battery over a distance of tens of kilometers. When the battery reaches a certain threshold level of charge (e.g., about 30%), the internal combustion engine starts and drives the current generator, making it possible to generate the power required to charge the battery and keep the electric motor running.

[0209] According to a first embodiment, the invention relates to the use of a lubricant composition according to the invention for preventing and / or inhibiting and / or alleviating problems associated with cold starts of an engine.

[0210] According to a second embodiment, the invention relates to the use of a lubricant composition according to the invention for preventing and / or inhibiting and / or slowing down corrosion phenomena that may occur in said engine.

[0211] According to a third embodiment, the invention relates to the use of a lubricant composition according to the invention for preventing and / or inhibiting and / or slowing down wear of said engine.

[0212] According to a fourth embodiment, the present invention relates to the use of a lubricant composition according to the invention for preventing and / or inhibiting and / or slowing down the stratification phenomenon of said lubricant composition.

[0213] Within the meaning of the present invention, the term "separation" is understood to mean the phenomenon whereby the water present in the lubricant composition (initially in the form of an emulsion) spontaneously separates from the mixture to form a continuous aqueous phase.

[0214] The ability of a lubricant composition to prevent delamination can be evaluated, for example, according to the following protocol:

[0215] 1) Prepare 100 mL of a mixture comprising: 60 mL of the lubricant composition to be tested; 20 mL of water; and 20 mL of a fuel, such as E10 gasoline;

[0216] 2) stirring the mixture to make it uniform;

[0217] 3) The mixture was placed in a closed truncated conical flask and then baked in an oven at 60° C. for 18 hours.

[0218] After storage in the oven for 18 hours, the lubricant compositions were visually evaluated by an operator for their ability to prevent delamination.

[0219] If the mixture is found to be in the form of a single phase, this indicates that the emulsion is stable. The lubricant composition is then assigned a "PASS" rating, indicating that the lubricant composition has a very low susceptibility to demixing phenomena.

[0220] In contrast, in the case where the mixture is not homogeneous, in particular due to the formation of an oily supernatant phase, the lubricant composition is assigned a "FAIL" rating. The emulsion is not sufficiently stable and the lubricant composition is not sufficiently protected against demixing phenomena.

[0221] The invention also relates to a lubrication method for lubricating an internal combustion engine, in particular the engine of a plug-in hybrid vehicle or a hybrid vehicle with a range extender, comprising contacting at least one component of the engine with a lubricant composition according to the invention.

[0222] The variations and embodiments of the viscosity index improver additive, the organo-molybdenum compound, the first detergent additive and the second detergent additive described in detail below are also applicable to the various uses defined above.

[0223] The particular, advantageous or preferred features for the use of the combination according to the invention define particular, advantageous or preferred combinations that can be used according to the invention.

[0224] The various aspects of the present invention are better illustrated by the following examples.

[0225] Example

[0226] Example 1: Preparation of lubricant composition

[0227] Lubricant compositions C1, C2, C3* and C4* were prepared from the following components:

[0228] - Base oil 1: Kinematic viscosity at 40°C equal to 19.57 mm2, measured according to standard ASTM D445 2 / s; measured according to standard ASTM D445, the kinematic viscosity at 100°C is equal to 4.23 mm 2 / s; the viscosity index is equal to 122 according to the standard ASTM D2270; the NOACK volatility is equal to 15% by weight of a group III base oil according to the standard DIN 51581;

[0229] - Additive VII: a viscosity index improver which is a conventional olefin polymer;

[0230] -MoDTC compounds: dialkyl dithiocarbamate molybdenum compounds, available from Adeka Corporation under the trademark "Sakuralube "Commercial purchase;

[0231] -PPD: pour point depressant;

[0232] - Additive Package 1: A conventional additive package comprising 5 wt% of a first detergent additive of the type: magnesium sulfonate and 15 wt% of a second detergent additive of the type: calcium salicylate. Additive Package 1 does not include any other detergent additives.

[0233] - Additive Package 2: A conventional additive package. Additive Package 2 differs 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 detergent additive of the type: calcium salicylate, which is the only detergent additive. Additive Package 2 does not contain any other detergent additives, in particular no magnesium-based detergent additives.

[0234] - Additional detergent additives: conventional detergent additives, such as magnesium sulfonate.

[0235] More specifically, compositions C1, C2, C3* and C4* were prepared by mixing, at a temperature level of 60° C., the compounds described in Table 2. The percentages indicated correspond to percentages by weight relative to the total weight of the composition.

[0236] Table 2

[0237]

[0238] Compositions C1 and C2 are compositions according to the invention.

[0239] Composition C3* is a comparative composition since it does not contain an organo-molybdenum compound.

[0240] Composition C4* is a comparative composition as it does not contain a magnesium based detergent additive.

[0241] Example 2: Ability to prevent delamination

[0242] The ability of the lubricant compositions prepared as described above to prevent delamination phenomena was evaluated according to the following protocol:

[0243] A 100 mL composition was prepared by mixing the following: 60 mL of the lubricant composition to be tested; 20 mL of water; and 20 mL of E10 type gasoline fuel. The composition was then mixed for 1 minute using an ultraturax (10,000 rpm). The composition was poured into a closed truncated conical flask and then placed in an oven at 60°C for 18 hours.

[0244] After 18 hours of storage in the oven, the flasks were recovered and the ability of the lubricant composition to prevent demixing was visually evaluated by an operator.

[0245] If the mixture is found to be in the form of a single phase, this indicates that the emulsion is stable. The lubricant composition is then assigned a "PASS" rating, indicating that the lubricant composition has a very low susceptibility to demixing phenomena.

[0246] In contrast, in the case of an inhomogeneous mixture, in particular due to the formation of an oily supernatant phase, the lubricant composition is assigned a "FAIL" rating. The emulsion is not sufficiently stable and the aqueous phase separates from the oil phase. The lubricant composition does not adequately prevent the stratification phenomenon.

[0247] The obtained results are shown in Table 3.

[0248] Table 3

[0249] C1 C2 C3* C4* result PASS PASS FAIL FAIL

[0250] The compositions C1 and C2 according to the invention are used to effectively prevent delamination phenomena.

[0251] In contrast, the emulsions obtained from lubricant compositions C3* and C4* were not stable. Therefore, the latter lubricant compositions could not be used to prevent the delamination phenomenon.

Claims

1. A lubricant composition comprising: - at least one base oil; - 0.1% to 13% by weight of at least one viscosity index improver additive, relative to the total weight of the lubricant composition; at least one organic molybdenum compound, containing at least 400 ppm by weight of the element molybdenum relative to the total weight of the lubricant composition; - at least a first detergent additive selected from magnesium salts of carboxylic acids, magnesium salts of sulfonic acids, magnesium salts of salicylates, magnesium salts of naphthenic acids, magnesium salts of phenols and any mixtures thereof; - optionally, at least a second detergent additive selected from calcium salts of carboxylic acids, calcium salts of sulfonic acids, calcium salts of salicylates, calcium salts of naphthenic acids, calcium salts of phenols and any mixtures thereof, in, The combined content of magnesium and calcium elements is at least 1000 ppm by weight relative to the total weight of the lubricant composition.

2. The lubricant composition according to claim 1, wherein The content of the molybdenum element is less than or equal to 1,500 ppm by weight relative to the total weight of the lubricant composition.

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

4. The lubricant composition according to any one of claims 1 to 3, wherein The lubricant composition comprises at least a second detergent additive selected from calcium salts of carboxylic acids, calcium salts of sulfonic acids, calcium salts of salicylates, calcium salts of cyclopentane acids, calcium salts of phenols and any mixture thereof; and the ratio of the calcium element content to the magnesium element content is 10:1 to 1:

10.

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

1.

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

7. A lubricant composition according to any one of the preceding claims, wherein The organic molybdenum compound is selected from molybdenum dithiocarbamates.

8. Use of a lubricant composition according to any one of the preceding claims for lubricating an internal combustion engine.

9. The method according to claim 8, for lubricating an internal combustion engine of a plug-in hybrid vehicle or a hybrid vehicle with a range extender.

10. The use according to claim 8 or claim 9, for: - preventing and / or inhibiting and / or mitigating problems associated with cold starts of said engine; and / or - prevent and / or inhibit and / or slow down possible corrosion phenomena in the engine; and / or - preventing and / or inhibiting and / or slowing down wear of said engine; and / or - preventing and / or inhibiting and / or slowing down the delamination phenomenon of the lubricant composition.

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