LUBRICANT COMPOSITION WITH IMPROVED COLD STABILITY AND FUEL-ECONOMY PROPERTIES

Info

Publication number: 20240059997
Type: Application
Filed: Jan 4, 2022
Publication Date: Feb 22, 2024
Applicant: TotalEnergies OneTech (COURBEVOIE)
Inventors: Mickael DEBORD (SOLAIZE), Khalid AIT-HAMMOU (SOLAIZE), Samira ADJAL (SOLAIZE), Jerôme VALADE (SOLAIZE)
Application Number: 18/271,119

Abstract

The invention relates to a lubricant composition comprising at least: a base oil, a friction modifier comprising molybdenum, a boron-containing dispersant, a polymer comprising repeating units which can be obtained by polymerization of monomers (a) with the formula (I): wherein: R1 represents a hydrogen atom or a methyl moiety, X1 represents a moiety chosen from: —O—, —O(AO)m, or —NH—, each moiety A independently representing a C2-C4 alkylene moiety and m represents an integer from 0 to 10. R2 is a polybutylene moiety, and p is equal to 0 or 1.

Description

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. National Phase Application under 35 U.S.C. § 371 of International Patent Application No. PCT/EP2022/050092 filed Jan. 4, 2022, which claims priority of French Patent Application No. 21 00094 filed Jan. 6, 2021. The entire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The invention relates to the field of lubricant compositions, more particularly to the properties of fuel economy (FE) and of cold stability of lubricant compositions. The invention relates to the combined use of at least one molybdenum friction modifier, at least one boron-containing dispersant and at least one (meth)acrylate copolymer, for improving the fuel economy (FE) and cold stability properties of a lubricant composition also comprising at least one base oil.

BACKGROUND

The need for high-performance lubricant compositions is increasing. More particularly, due to increasingly severe conditions of use, e.g. due to more extreme temperatures or very high mechanical stresses.

The spacing of oil changes and the reduction in the size of lubrication systems also lead to an increase in the need for high-performance lubricant compositions. The energy efficiency and in particular the improvement of the Fuel Economy (FE) of lubricant compositions or the reduction of the fuel consumption of engines, more particularly of vehicle engines, are increasingly important goals and lead to the increasing use of high-performance lubricant compositions.

High-performance lubricant compositions should thus have improved properties, more particularly with regard to kinematic viscosity, viscosity index, volatility, dynamic viscosity or cold pour point.

Thermal stability and oxidation resistance are also properties to be improved for high-performance lubricant compositions.

Engine lubricant compositions thus have to fulfill many purposes.

The lubrication of the parts sliding on one another plays a decisive role, more particularly in reducing friction and wear, which in particular saves fuel.

An essential requirement of engine lubricant compositions relates to environmental aspects. It has in fact become essential to reduce the consumption of lubricant compositions as well as the consumption of fuel, in particular with the aim of reducing emissions of CO₂.

The nature of lubricant compositions for motor vehicles has an influence on fuel consumption. Automotive engine lubricant compositions which save energy are often referred to as fuel economy (FE).

The reduction of energy losses is thus constantly sought in the field of automotive lubricant compositions.

There is thus a need to have lubricant compositions for engines, in particular for vehicle engines, which are used for providing a solution to some or all of the problems of the lubricant compositions of the state of the art, more particularly with regard to the cold stability of the lubricant composition and the fuel economy properties obtained due to a low coefficient of friction.

SUMMARY

The invention relates first of all to a lubricant composition comprising:

- at least one base oil,
- at least one friction modifier comprising molybdenum, such that the amount of molybdenum in the lubricant composition ranges from 100 ppm to 1,500 ppm by weight, with respect to the total weight of the lubricant composition,
- at least one boron-containing dispersant, such that the amount of boron in the lubricant composition ranges from 10 ppm to 300 ppm, with respect to the total weight of the lubricant composition,
- from 0.1% to 10% by weight of dry matter, with respect to the total weight of the lubricant composition, of a polymer comprising repeating units which could be obtained by polymerization of monomers (a) with the formula (I):

- wherein:
- R1 represents a hydrogen atom or a methyl moiety,
- X1 represents a moiety chosen from: —O—, —O—(AO)m, or —NH—, each moiety A independently representing a C2-C4 alkylene moiety and m represents an integer from 0 to 10.
- R2 is a polybutylene moiety, and
- p is equal to 0 or 1.

According to one embodiment, the lubricant composition according to the invention comprises:

- at least 50% by weight, with respect to the total weight of the lubricant composition, of one or several base oils,
- from 0.01% to 10% by weight, with respect to the total weight of the lubricant composition, of one or several friction modifiers comprising molybdenum, such that the amount of molybdenum in the lubricant composition ranges from 300 ppm to 1,000 ppm by weight, with respect to the total weight of the lubricant composition,
- from 0.01% to 10% by weight, with respect to the total weight of the lubricant composition, of one or several boron-containing dispersants, such that the amount of boron in the lubricant composition ranges from 10 ppm to 300 ppm by weight, with respect to the total weight of the lubricant composition,
- from 0.5% to 5% by weight of dry matter, with respect to the total weight of the lubricant composition, of a copolymer which can be obtained by copolymerization of monomers (a) with the formula (I) and monomers (b) with the formula (II):

- wherein:
- R3 represents a hydrogen atom or a methyl moiety,
- X2 represents a —O— or —NH— moiety,
- R4 moieties independently represent a C2-C4 alkylene moiety,
- R5 represents a C1-08 alkyl moiety, and
- q is an integer from 1 to 20.

Advantageously, the lubricant composition according to the invention comprises:

- at least 70% by weight, with respect to the total weight of the lubricant composition, of one or several base oils,
- from 0.01% to 5% by weight, with respect to the total weight of the lubricant composition, of one or several friction modifiers comprising molybdenum, such that the amount of molybdenum in the lubricant composition ranges from 500 ppm to 1,000 ppm by weight, with respect to the total weight of the lubricant composition,
- from 0.01% to 5% by weight, with respect to the total weight of the lubricant composition, of one or several boron-containing dispersants, such that the amount of boron in the lubricant composition ranges from 20 ppm to 300 ppm by weight, with respect to the total weight of the lubricant composition,
- from 0.8% to 3% by weight of dry matter, with respect to the total weight of the lubricant composition, of a copolymer comprising, with respect to the total weight of the copolymer:
- from 1% to 50% by weight of units derived from monomers (a), and
- from 1% to 80% by weight of units derived from monomers (b).

Preferentially, the lubricant composition according to the invention has a kinematic viscosity at 100° C., measured according to the ASTM D445 standard, ranging from 3.8 mm²/s to 21.9 mm²/s.

Preferentially, the friction modifier comprising molybdenum is an organomolybdenum compound, in particular a compound chosen from a molybdenum dithiocarbamate derivative (MoDTC), a molybdenum dithiophosphate derivative (MoDTP) or a sulfur-free molybdenum complex, preferentially a molybdenum dithiocarbamate derivative (MoDTC).

Preferentially, the boron-containing dispersant is chosen from boron-containing succinimides, preferentially from boron-containing polyisobutene succinimides.

A further subject matter of the invention is the use, in a lubricant composition comprising a base oil, of one or several molybdenum friction modifiers and one or several boron-containing dispersants, of a copolymer comprising repeating units which can be obtained by polymerizing monomers (a) with the formula (I):

- wherein:
- R1 represents a hydrogen atom or a methyl moiety,
- X1 represents a moiety chosen from: —O—, —O(AO)m, or —NH—, each moiety A independently representing a C2-C4 alkylene moiety and m represents an integer from 0 to 10.
- R2 is a polybutylene moiety, and
- p is equal to 0 or 1,

for improving the cold stability of said lubricant composition.

Preferentially, the use of the copolymer according to the invention makes it possible to:

- lubricate the parts of a motor vehicle engine, and/or
- reduce friction between the engine parts, and/or
- reduce the fuel consumption of the engine.

DETAILED DESCRIPTION

The present invention primarily relates to a lubricant composition comprising:

- at least one base oil,
- at least one friction modifier comprising molybdenum, such that the amount of molybdenum in the lubricant composition ranges from 100 ppm to 1,500 ppm by weight, with respect to the total weight of the lubricant composition,
- at least one boron-containing dispersant, such that the amount of boron in the lubricant composition is from 10 ppm to 300 ppm, with respect to the total weight of the lubricant composition,
- from 0.1 to 10% by weight of dry matter, with respect to the total weight of the lubricant composition, of a polymer comprising repeating units which could be obtained by polymerization of monomers (a) with the formula (I):

- wherein:
  - R¹represents a hydrogen atom or a methyl moiety,
  - X¹represents a moiety chosen from: —O—, —O(AO)m, or —NH—, each moiety A independently representing a C2-C4 alkylene moiety and m represents an integer from 0 to 10,
  - R²is a polybutylene moiety, and
  - p is 0 or 1.

Copolymer

The lubricant composition according to the invention comprises at least one polymer, in particular a copolymer, comprising repeating units which can be obtained by polymerizing monomers (a) with the formula (I):

- wherein:
  - R¹represents a hydrogen atom or a methyl moiety,
  - X¹represents a moiety chosen from: —O—, —O(AO)_m, or —NH—, each moiety A independently representing a C₂-C₄alkylene moiety and m represents an integer from 0 to 10,
  - R 2 is a polybutylene moiety, and
  - p is 0 or 1.

As defined in the present invention, the term “(meth)acrylate” refers to a methacrylate or an acrylate. By analogy, as defined by the present invention, the term “(meth)acrylamide” refers to a methacrylamide or an acrylamide.

Preferentially, R¹is a methyl moiety.

Examples of a C₂-C₄alkylene moiety include particular an ethylene moiety, a 1,2- or 1,3-propylene moiety or again a 1,2, 1,3- or 1,4-butylene moiety.

Preferentially, m is an integer ranging from 0 to 4, more preferentially from 0 to 2.

Whenever m is greater than or equal to 2, each A can be identical or different, and the fragments (AO)_mcan be linked randomly or in blocks.

Preferentially, the moiety X¹is a —O— or —O(AO)_m— moiety, more preferentially a —O— or —O(CH₂CH₂O)— moiety.

R²is a polybutylene moiety.

“Polybutylene moiety”, as defined by the invention, means a moiety obtained by the removal of a hydrogen atom from a hydrocarbon polymer containing, as essential structural unit, at least one 1,2-butylene or isobutylene monomer.

Examples of a hydrocarbon polymer suitable for the preparation of a polybutylene moiety R², include in particular, a copolymer comprising units derived from isobutene and/or from 1,2-butylene or yet a polymer obtained by the hydrogenation of the terminal double bond of a polybutadiene obtained by the addition (1,2) of buta-1,3-diene monomers.

The hydrocarbon polymer can be a sequence-defined polymer or a random polymer.

The hydrocarbon polymer can further contain at least one structural unit distinct from the isobutylene or 1,2-butylene units. The hydrocarbon polymer can e.g. comprise one or a plurality of the following units:

- (1) unsaturated aliphatic hydrocarbons,
- (2) alicyclic unsaturated hydrocarbons, and
- (3) unsaturated hydrocarbons containing an aromatic moiety, other than isobutene, but-1-ene and but-2-ene units.

If the hydrocarbon polymer has a double bond, the double bond can be partially or completely hydrogenated by hydrogenation.

Preferentially, the isobutylene and 1,2-butylene units represent at least 30 mol % of the total number of structural units forming the hydrocarbon polymer, preferentially at least 40 mol %, preferentially at least 50 mol %, preferentially at least 60 mol %.

The total number of butylene units (isobutylene and/or 1,2 butylene), relative to the total number of structural units of the hydrocarbon polymer, can be determined by analyzing the hydrocarbon polymer by ¹³C nuclear magnetic resonance spectroscopy and using the following equation:

$Total number of butylene units = \frac{(Integral value A) \times 2 + (Integral value B) \times 4}{(Integral value C of all carbon peaks)}$

The ¹³C nuclear magnetic resonance spectrum shows a peak derived from an isobutylene methyl moiety at 30-32 ppm (integral value A), and a peak derived from a branched methylene moiety (—CH₂—CH(CH₂CH₃)—) of 1,2-butylene at 26-27 ppm in integral value (integral value B). The total number of isobutylene and 1,2-butylene [units] can be determined from the integral values of the peaks and an integral value (integral value C) of the peaks of all the carbon atoms of the hydrocarbon polymer.

The monomers (a) are typically obtained by esterification or amidation of a (co)polymer (Y) containing a hydroxyl moiety or an amine moiety.

Examples of (co)polymers (Y) (i.e. the (co)polymer containing a hydroxyl moiety or an amine moiety), can include examples of (co)polymers (Y1) to (Y4) containing a hydroxyl moiety and (co)polymers (Y5) containing an amine moiety as defined herein below.

Addition products of alkylene oxide (Y1): (co)polymers which can be obtained by bringing in contact an alkylene oxide, e.g. ethylene oxide or propylene oxide, with a polymer chosen from: (1) a hydrocarbon polymer obtained by polymerizing an unsaturated aliphatic hydrocarbon; (2) an unsaturated alicyclic hydrocarbon; (3) an unsaturated aromatic hydrocarbon, in particular chosen from C₂-C₃₆olefins; and derivatives thereof, in the presence of an ionic polymerization catalyst, e.g. a sodium catalyst.

The products obtained by hydroboration (Y2): (co)polymer which can be obtained by hydroboration of hydrocarbon polymers, in particular same described in U.S. Pat. No. 4,316,973.

Addition products of maleic anhydride-ene-amine alcohol (Y3): (co)polymers which can be obtained by imidation of the product obtained by an Alder-ene reaction between a hydrocarbon polymer having a double bond and maleic anhydride in the presence of an amino alcohol.

Products which can be obtained by hydroformylation and hydrogenation (Y4): (co)polymer(s) which can be obtained by hydroformylation of a hydrocarbon polymer having a double bond, followed by a hydrogenation step. The products described in JP-A 63-175096 can be mentioned as examples.

Addition products of maleic an hydride-ene-ethylenediamine (Y5): (co)polymers which can be obtained by imidation of a product obtained by an Alder-ene reaction between a hydrocarbon polymer having a double bond and maleic anhydride in the presence of ethylenediamine.

Preferentially, the (co)polymer (Y) is chosen from (co)polymers (Y1), (Y2) and (Y3), more preferentially from (co)polymers (Y) and (Y1).

The number-average molecular weight (Mn) of each of (co)polymers (Y) is preferentially from 1,000 to 25,000 g·mol⁻¹, more preferentially from 2,000 to 20,000 g·mol⁻¹, particularly preferentially from 3,000 to 15,000 g·mol⁻¹, more preferentially from 4,000 to 10,000 g·mol⁻¹.

Advantageously, the crystallization temperature of the (co)polymer (Y) is less than or equal to −40° C., more preferentially less than or equal to −50° C., in particular less than or equal to −55° C., typically less than or equal to −60° C.

The crystallization temperature of the (co)polymer (Y) or (co)polymer (A) can be measured by means of a differential scanning calorimeter such as “Unix® DSC7” (PerkinElmer). The crystallization temperature is measured during isothermal cooling of a sample (5 mg) of the (co)polymer (Y) or of the (co)polymer (A) from 100° C. to −80° C. at a rate of 10° C./min.

According to one embodiment, the copolymer further comprises repeating units which can be obtained by the polymerization of monomers (b) with the formula (II):

- wherein:
- R³represents a hydrogen atom or a methyl moiety;
- X²is a moiety represented by —O— or —NH—;
- R⁴moieties independently represent a C₂-C₄alkylene moiety;
- R⁵is a C₁-C₈alkyl moiety; and
- q is an integer different from zero ranging from 1 to 20.

Preferentially, R³is a methyl moiety.

Preferentially, X²is an —O— moiety.

Examples of C₂-C₄alkylene moieties include in particular, ethylene, isopropylene, 1,2-or 1,3-propylene, isobutylene and 1,2-, 1,3- or 1,4-butylenes.

Preferentially, q is equal to 1 or 2.

When q is equal to or greater than 2 and each R⁴can be identical or different, and the (R⁴O)_qfragments can be linked randomly or in blocks.

Examples of C₁-C₈alkyl moieties include in particular methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-heptyl, isoheptyl, n-hexyl, 2-ethylhexyl, n-pentyl and n-octyl.

Among such C₁-C₈alkyl moieties, C₁-C₆alkyl moieties will be preferred, more preferentially C₁-C₅alkyl moieties, typically C₄alkyl moieties.

Examples of monomers (b) include methoxypropyl (meth)acrylate, methoxybutyl (meth)acrylate, methoxyheptyl (meth)acrylate, methoxyhexyl (meth)acrylate, methoxypentyl (meth)acrylate, methoxyoctyl (meth)acrylate, ethoxyethyl (meth)acrylate, ethoxybutyl (meth)acrylate, ethoxypropyl (meth)acrylate, (meth)acrylate, ethoxypropyl (meth)acrylate ethoxyhexyl (meth)acrylate, ethoxypentyl (meth)acrylate, ethoxyoctyl (meth)acrylate, propoxymethyl (meth)acrylate, propoxyethyl (meth)acrylate, propoxypropyl (meth)acrylate, propoxybutyl (meth)acrylate, propoxyheptyl (meth)acrylate, propoxyhexyl (meth)acrylate, propoxypentyl (meth)acrylate, propoxyoctyl (meth)acrylate, butoxymethyl (meth)acrylate, butoxyethyl (meth)acrylate, butoxypropyl (meth)acrylate, butoxybutyl (meth)acrylate, butoxyheptyl (meth)acrylate, butoxyhexyl (meth)acrylate, butoxypentyl (meth)acrylate, butoxyoctyl (meth)acrylate and C₁-C₈esters of (meth)acrylic acid and alcohols with 2 to 20 moles of ethylene oxide, propylene oxide or butylene oxide.

Advantageously, the monomers (b) are chosen from ethoxyethyl (meth)acrylate and butoxyethyl (meth)acrylate.

According to a preferred embodiment, the monomers (b) are distinct from the monomers (a).

According to one embodiment, the copolymer of the invention can further comprise, in addition to the units derived from the monomers (a) and (b), additional repeating units which can obtained by the polymerization of monomers chosen from:

- monomers (c) chosen from C₁-C₄alkyl (meth)acrylates,
- monomers (d) chosen from alkyl (meth)acrylates wherein the alkyl moiety is chosen from linear C₁₂-C₃₆alkyl moieties, and/or
- monomers (e) chosen from alkyl (meth)acrylates wherein the alkyl moiety is chosen from branched C₁₂-C₃₆alkyl moieties.

Examples of monomers (c) include in particular: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate and butyl (meth)acrylate.

Preferentially, the monomers (C) are chosen from methyl (meth)acrylate and butyl (meth)acrylate, more preferentially from butyl (meth)acrylates.

Examples of monomers (d) include in particular: N-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, n-pentadecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-octadecyl (meth)acrylate, n-icosyl (meth)acrylate, n-tetracosyl (meth)acrylate, (meth)acrylate, n-triacontyl (meth)acrylate and n-hexatriacontyl (meth)acrylate.

Preferentially, the monomers (d) are chosen from alkyl (meth)acrylates having a linear C₁₂-C₂₈alkyl moiety, more preferentially from alkyl (meth)acrylates having a linear C₁₂-C₂₂alkyl moiety.

The (co)polymer can also contain repeating units which can be obtained by polymerizing monomers (e) represented by the following formula (III):

- wherein:
- R⁶represents a hydrogen atom or a methyl moiety;
- X³is a —O— or —NH— moiety;
- R⁷moieties independently represent a C₂-C₄alkylene moiety;
- R⁸and R⁹independently represent a linear C₄-C₂₄alkyl moiety; and
- r is an integer between 0 and 20.

Preferentially, R⁶is a methyl moiety.

Preferentially, X³is a —O— moiety.

Examples of C₂-C₄alkylene moieties include in particular ethylene, isopropylene, 1,2- or 1,3-propylene, isobutylene and 1,2-, 1,3- or 1,4-butylene moieties.

Preferentially, r is an integer ranging from 0 to 5, more preferentially from 0 to 2.

When r is greater than or equal to 2, the R⁷moieties can be either identical or different, and the (R⁷O)r fragments can be linked randomly or in blocks.

Examples of linear C₄-C₂₄alkyl moieties include in particular n-butyl, n-heptyl, n-hexyl, n-pentyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, n-eicosyl and n-tetracosyl.

Preferentially, the moieties R⁸and R⁹are chosen, independently, from linear C₆-C₂₄alkyl moieties, more preferentially from linear C₆-C₂₀alkyl moieties, typically from linear C₈-C₁₆alkyl moieties.

Examples of monomers (e) include in particular: 2 2-octyldecyl (meth)acrylate, an ester of ethylene glycol mono-2 2-octylpentadecyl ether and (meth)acrylic acid, 2 2-octyldodecyl (meth)acrylate, 2-n-decyltetradecyl (meth)acrylate, 2-n-dodecylhexadecyl (meth)acrylate, 2-tetradecyl (tetradecylacrylate, 2-heptadecyl (meth)acrylate, 2-hexadecyldocosyl (meth)acrylate, 2-eicosyldocosyl (meth)acrylate, 2-tetracosylhexacosyl (meth)acrylate and N-2-octyldecyl (meth)acrylamide.

Preferentially, the monomers (e) are chosen from alkyl (meth)acrylates wherein the alkyl moiety is chosen from branched C₁₂-C₃₆alkyl moieties, more preferentially C₁₄-C₃₂alkyl moieties, typically C₁₆-C₂₈alkyl moieties.

Monomers (b) to (e) are obtained by reacting a terminal hydroxyl moiety or an amine moiety of a compound comprising a hydrocarbon moiety with a (meth)acrylic acid, but not by modifying a hydrocarbon polymer. Thus, the monomers (b) to (e) are not monomers containing polyolefins. Furthermore, the monomers obtained by the addition of 2 to 20 moles of ethylene oxide, propylene oxide or butylene oxide to C₁-C₈alcohols and the monomers obtained by the addition of 1 to 20 moles of ethylene oxide, propylene oxide or butylene oxide to alcohols containing branched C₁₀-C₅₀alkyl moieties are also not obtained by modifying hydrocarbon polymers. Thereby, said monomers are not monomers containing polyolefins.

According to one embodiment, the (co)polymer of the invention comprises, in addition to the units derived from the monomers (a) to (e), repeating units obtained by a polymerization of monomers chosen from the group consisting of:

- (f) nitrogen-containing monomers,
- (g) monomers containing a hydroxyl moiety, and
- (h) phosphorus-containing monomers (h).

Examples of monomer (f) include the following monomers (f1) to (f4):

Examples of monomers (f1): (meth)acrylamides; monoalkyl(meth)acrylamides, in particular the monomers wherein a C1-C4 alkyl moiety is bonded to a nitrogen atom such as e.g. N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-n-butyl(meth)acrylamide and N-isobutyl(meth)acrylamide]; N-(N′-monoalkylaminoalkyl)(meth)acrylamides, especially the monomers wherein a C2-C6 aminoalkyl moiety wherein a C1-C4 alkyl moiety is bonded to a nitrogen atom such as e.g. N-(N′-methylaminoethyl)(meth)acrylamide, N-(N′-ethylaminoethyl)(meth)acrylamide, N-(N′-isopropylamino-butyl)acrylamide, N-N′ butyl)(meth)acrylamide and N-(N′-isobutylamino-n-butyl)(meth)acrylamide; dialkyl(meth)acrylamides; in particular those wherein two C1-C4 alkyl moieties are bonded to a nitrogen atom such as e.g. N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide and N,N-di-n-butyl(meth)acrylamide; N-(N′,N′-dialkylaminoalkyl)(meth)acrylamides, especially those comprising a C2-C6 aminoalkyl moiety wherein two C1-C4 alkyl moieties are bonded to a nitrogen atom of an aminoalkyl moiety such as e.g. N-(N′,N′-dimethylaminoethyl)(meth)acrylamide, N-(N′,N′-diethylaminoethyl)(meth)acrylamide, N-(N′, N′-dimethylaminopropyl)(meth)acrylamide and N-(N′,N′-di-n dibutylamino)(meth)acrylamide; the N-vinylcarboxylic acid amides such as e.g. N-vinylformamide, N-vinylacetamide, N-vinyl-n-isopropionic acid amide, N-vinyl-isopropionic acid amide and N-vinylhydroxyacetamide.

Example of monomer (f2): 4-nitrostyrene.

Examples of monomers (f3):

- monomers containing primary amine moieties: C3-C6 alkenylamines, such as e.g. (meth)allylamine and crotylamine; C2-C6 aminoalkyl (meth)acrylates, such as e.g. aminoethyl (meth)acrylate;
- monomers containing secondary amine moieties: monoalkylaminoalkyl (meth)acrylates, in particular those comprising a C2-C6 aminoalkyl moiety wherein a C1-C6 alkyl moiety is bonded to a nitrogen atom, such as e.g. N-t-butylaminoethyl (meth)acrylate and N-methylaminoethyl (meth)acrylate; C6-C12-dialkenylamines, such as di(meth)allylamine;
- monomers containing tertiary amine moieties: dialkylaminoalkyl (meth)acrylates, in particular those comprising a C2-C6 aminoalkyl moiety wherein two C1-C6 alkyl moieties are bonded to a nitrogen atom, such as e.g. N,N-dimethylaminoethyl (meth)acrylate and N,N-diethylaminoethyl (meth)acrylate; Alicyclic (meth)acrylates comprising a nitrogen atom such as e.g. morpholinoethyl (meth)acrylate; aromatic monomers such as e.g. N-(N′,N′-diphenylaminoethyl)(meth)acrylamide, N,N-dimethylaminostyrene, 4-vinylpyridine, 2-vinylpyridine, N-vinylpyrrole, N-vinylpyrrolidone and N-vinylthiopyrrolidone], and
- hydrochlorides, sulfurates, phosphates and lower alkyl (C1-C8) monocarboxylates of said monomers, acetic acid and propionic acid being examples of monocarboxylic acids.

Example of a monomer containing a nitrile moiety (f4): (meth)acrylonitrile.

Monomers (f) are preferentially chosen among monomers (f1) and (f3), more preferentially among N-(N′,N′-diphenylaminoethyl)(meth)acrylamide, N-(N′,N′-dimethylaminoethyl)(meth)acrylamide, N-(N′,N′-diethylaminoethyl)(meth)acrylamide, N-(N′,N′-dimethylaminopropyl)(meth)ethyl acrylate, N,N-dimethylaminoethyl(meth)acrylate and N,N-diethylaminoethyl (meth)acrylate

Examples of monomers (g) include in particular:

- aromatic monomers containing a hydroxyl moiety, such as e.g. p-hydroxystyrene; C2-C6 hydroxyalkyl (meth)acrylates such as e.g. 2-hydroxyethyl (meth)acrylate and 2- or 3-hydroxypropyl(meth)acrylate; C1-C4 substituted mono- or bis-hydroxyalkyl (meth)acrylamides, such as e.g. N-N-bis(hydroxymethyl)(meth)acrylamide, N-N-bis-(hydroxypropyl)(meth) acrylamide and N,N-bis(2-hydroxybutyl)(meth)acrylamide; vinyl alcohol; C3-C12 alkenols such as (meth)allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1-octenol and 1-undecenol; C4-C12 alkene monools or diols such as 1-butene-3-ol, 2-butene-1-ol and 2-butene-1,4-diol; C1-C6 hydroxyalkl ethers C3-C10 alkenyl ethers e.g. 2-hydroxyethylpropenyl ether, C3-C10 alkenyl ethers or (meth)acrylates of polyhydric alcohols comprising from 3 to 8 hydroxyl moieties (in particular chosen among glycerol, pentaerythritol, sorbitol, sorbitan, diglycerol, sugars and sucrose) such as e.g. sucrose (meth)allyl ether.
- polyoxyalkylene glycols wherein the alkylene moiety is C2-C4 and the degree of polymerization is from 2 to 50; polyoxyalkylene polyols such as e.g. polyoxyalkylene ethers of polyhydric alcohols comprising from 3 to 8 hydroxyl moieties, the alkylene moiety being C2-C4, and the degree of polymerization ranging from 2 to 100; mono(meth)acrylates of C1-C4 alkyl ethers of polyoxyalkylene glycols or of polyoxyalkylene polyols such as e.g. polyethylene glycol (Mn from 100 to 300 g·mol⁻¹), polypropylene glycol mono(meth)acrylate (Mn: from 130 to 500 g·mol⁻¹), methoxy polyethylene glycol mono(meth)acrylate (Mn: from 110 to 310 g·mol⁻¹), the product of the addition of lauryl alcohol with ethylene oxide (2 to 30 moles), and polyoxyethylene mono(meth)acrylate (Mn: from 150 to 230 g·mol⁻¹) sorbitan.

The monomers (h) are chosen in particular from the following monomers (h1) and (h2).

Examples of monomers (h1): C2-C4 (meth)acryloyloxyalkyl phosphate esters such as e.g. (meth)acryloyloxyethyl phosphate and (meth)acryloyloxyisopropyl phosphate; alkenyl phosphate esters such as e.g. vinyl phosphate, allyl phosphate, propenyl phosphate, isopropenyl phosphate, butenyl phosphate, pentenyl phosphate, octenyl phosphate, decenyl phosphate and dodecenyl phosphate. The term “(meth)acryloyloxy” means acryloyloxy or methacryloyloxy.

Examples of monomers (h2): C2-C4 (meth)acryloyloxy alkyl phosphonic acids such as e.g. (meth)acryloyloxyethyl phosphonic acid; C2-C12 alkenyl phosphonic acids such as e.g. vinylphosphonic acid, allylphosphonic acid and octenylphosphonic acid.

Preferentially, the monomers (h) are chosen from monomers (hi), more preferentially from C2-C4 (meth)acryloyloxyalkyl phosphate esters, advantageously the monomers (h) are (meth)acryloyloxyethyl phosphate.

According to one embodiment, the (co)polymer of the invention comprises, in addition to the units derived from the monomers (a) to (h), repeating units obtained by polymerization of monomers (I) comprising at least two unsaturated moieties.

Examples of monomer (i) include divinylbenzene; C4-C12 alkadienes such as e.g. butadiene, isoprene, 1,4-pentadiene, 1,6-heptadiene and 1,7-octadiene; (di)cyclopentadiene; vinylcyclohexene and ethylidene-bicycloheptene, limonene, ethylene di(meth)acrylate, polyalkylene oxide glycol di(meth)acrylate pentaerythritol triallyl ether, trimethylolpropane tri(meth)acrylate, and the esters disclosed in WO 01/009242 such as e.g. a glycolic ester of an unsaturated carboxylic acid having a number-average molecular weight (Mn) greater than or equal to 500 g·mol⁻¹or an ester of an unsaturated alcohol and of a carboxylic acid.

The (co)polymer of the invention can also comprise, in addition to the units derived from monomers (a) to (i), repeating units obtained by a polymerization of monomers chosen from:

- (j) aliphatic hydrocarbons based monomers,
- (k) alicyclic hydrocarbon based monomers,
- (l) aromatic monomers based hydrocarbons,
- (m) monomers of vinyl esters, vinyl ethers and vinyl ketones,
- (n) monomers containing an epoxy moiety,
- (o) monomers containing a halogen,
- (p) unsaturated polycarboxylic acid ester type monomers.

Examples of monomer (j): C₂-C₂₀alkenes such as ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene and octadecene.

Examples of monomer (k): cyclopentene, cyclohexene, cycloheptene, cyclooctene and pinene.

Examples of monomers (I): styrene, a-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-butylstyrene, 4-phenylstyrene, 4-cyclohexylstyrene, 4-benzylstyrene, 4-crotylbenzene, indene and 2-vinylnaphthalene.

Examples of monomers (m): vinyl esters of C2-C12 saturated fatty acids such as vinyl acetate, vinyl propionate, vinyl butyrate and vinyl octanoate; C1-C12 alkyl, aryl or alkoxyalkylvinyl ethers (methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether; 2-ethylhexyl vinyl ether; phenyl vinyl ether; vinyl-2-methoxyethyl ether; and vinyl-2-butoxyethyl ether); and C1-C8 alkyl or aryl vinyl ketones (such as methyl vinyl ketone, ethyl vinyl ketone, and phenyl vinyl ketone).

Examples of monomers containing an epoxy moiety (n): glycidyl (meth)acrylate and glycidyl (meth)allyl ether.

Examples of monomers containing a halogen (o): vinyl chloride, vinyl bromide, vinylidene chloride, (meth)allyl chloride and halogenated styrenes such as e.g. dichlorostyrene.

Examples of unsaturated polycarboxylic acid ester (p) monomers: alkyl, cycloalkyl or aralkyl esters of unsaturated polycarboxylic acids [C1 -C8 alkyl diesters (dimethyl maleate, dimethyl fumarate, diethyl maleate and dioctyl maleate) of unsaturated dicarboxylic acids (such as maleic acid, fumaric acid and itaconic acid)].

The composition of the copolymer can be determined by proton nuclear magnetic resonance spectroscopy (¹H NMR) or by gas chromatography coupled with mass spectrometry (GC-MS).

Preferentially, the monomers (a) represent from 1% to 50% by weight, with respect to the total weight of the (co)polymer, more preferentially from 5% to 40% by weight, in particular from 8% to 40% by weight, typically from 10% to 30% by weight.

Preferentially, the monomers (b) represent from 1% to 80% by weight, with respect to the total weight of the (co)polymer, more preferentially from 5% to 60% by weight, in particular from 10% to 35% by weight, typically from 10% to 30% by weight.

Preferentially, the monomers (a) and (b) together represent at least 10% by weight of the total weight of the (co)polymer, more preferentially from 15% to 90% by weight, in particular from 20% to 80% by weight, typically from 20% to 50% by weight.

Preferentially, the monomers (c) represent from 1% to 80% by weight, more preferentially from 20% to 70% by weight, in particular from 30% to 65% by weight, with respect to the total weight of the (co)polymer.

Preferentially, the monomers (d) represent from 1% to 40% by weight, more preferentially from 1% to 35% by weight, in particular from 2% to 30% by weight, with respect to the total weight of the (co)polymer.

Preferentially, the monomers (e) represent from 0% to 40% by weight, more preferentially from 1% to 30% by weight, in particular from 1% to 25% by weight, with respect to the total weight of the (co)polymer.

Preferentially, the monomers (f), (h) and (h) each represent from 0% to 15% by weight, more preferentially from 1% to 12% by weight, in particular from 2% to 10% by weight, with respect to the total weight of the (co)polymer.

Preferentially, the monomers (i) represent from 0.01 ppm to 200 ppm by weight, with respect to the total weight of the (co)polymer, more preferentially from 0.005 ppm to 50 ppm by weight, in particular from 0.1 ppm to 20 ppm by weight.

Preferentially, the monomers (j) to (p) each represent from 0 ppm to 10% by weight, more preferentially from 1% to 7% by weight, in particular from 2% to 5% by weight, with respect to the total weight of the (co)polymer.

Preferentially, the copolymer has a mass average molar weight (Mw) by weight from 5,000 g·mol⁻¹to 2,000,000 g·mol⁻¹, more preferentially from 150,000 g·mol⁻¹to 1,000,000 g·mol⁻¹, in particular from 230,000 g·mol⁻¹to 1,000,000 g·mol⁻¹, in particular from 300,000 g·mol⁻¹to 800,000 g·mol⁻¹. The mass average molar weight can be determined by steric exclusion chromatography with poly(methyl methacrylate) (PMMA) standards.

The (co)polymer preferentially has a crystallization temperature of less than or equal to −30° C., more preferentially less than or equal to −40° C., in particular less than or equal to −50° C., typically less than or equal to −60° C.

The copolymer used according to the invention can be synthesized according to any method well known to a person skilled in the art or can be found on the market.

Specific examples include a method wherein the monomers are subject to polymerization in solution in a solvent in the presence of a polymerization catalyst.

Examples of solvents include toluene, xylene, C9-C10 alkylbenzenes, methyl ethyl ketone and mineral oils.

Examples of polymerization catalysts: azo catalysts (such as 2,2′-azobis(2-methylbutyronitrile) and 2,2′-azobis(2,4-dimethylvaleronitrile), peroxide catalysts (such as benzoyl peroxide, cumyl peroxide and lauryl peroxide) and redox catalysts (such as mixtures of benzoyl peroxide and tertiary amines). If need be, a known chain transfer agent (such as C2-C20 alkyl mercaptans) can also be used.

The polymerization temperature is preferentially from 25° C. to 140° C., more preferentially from 50° C. to 120° C.

The (co)polymer of the invention can also be obtained by bulk, emulsion or suspension polymerization

When the (co)polymer is a copolymer, same can be of one of the following types: a random addition polymer, an alternative copolymer, a grafted copolymer and a sequence-defined copolymer.

The copolymer of the invention is used in the lubricant composition, preferentially in an amount ranging from 0.1% to 10% by weight of dry matter, more preferentially from 0.5% to 5% by weight of dry matter, even more preferentially, from 0.8% to 3% by weight of dry matter, with respect to the total weight of the lubricant composition.

Molybdenum Friction Modifier

The lubricant composition comprises one or several friction modifiers comprising molybdenum, such that the amount of molybdenum in the lubricant composition ranges from 100 ppm to 1500 ppm by weight, preferentially from 300 ppm to 1000 ppm by weight, more preferentially, from 500 ppm to 1000 ppm by weight, with respect to the total weight of the lubricant composition.

The amount of molybdenum, in particular of MoDTC compounds, in the lubricant composition according to the invention can be measured according to the standard ASTM D5185.

A lubricant composition according to the invention can comprise from 0.01% to 10%, preferentially 0.1% to 5% by weight, preferentially 0.5% to 3% by weight of molybdenum friction modifying agent(s), with respect to the total weight of the composition.

Preferentially, the friction modifier(s) comprising molybdenum are chosen from organomolybdenum compounds, especially chosen from molybdenum dithiocarbamate (MoDTC) derivatives, molybdenum dithiophosphate (MoDTP) derivatives or sulfur free molybdenum complexes, more preferentially from molybdenum dithiocarbamate derivatives (MoDTC).

Molybdenum dithiocarbamate compounds (MoDTC compound) are complexes formed of a metal core bonded to one or a plurality of ligands independently chosen from alkyl dithiocarbamate moieties. The MoDTC compound of the compositions according to the invention can comprise from 1% to 40%, preferentially from 2% to 30%, more preferentially from 3% to 28%, even more preferentially from 4% to 15% by weight of molybdenum, with respect to the total weight of the MoDTC compound.

The MoDTC compound used according to the invention can be chosen from compounds the core of which comprises two molybdenum atoms (dimeric MoDTC) and compounds the core of which comprises three molybdenum atoms (trimeric MoDTC).

The trimeric MoDTC compounds generally have the formula Mo₃S_kL_nwherein:

- k represents an integer at least equal to 4, preferentially ranging from 4 to 10. advantageously from 4 to 7;
- n represents an integer from 1 to 4 and
- L represents an alkyl dithiocarbamate moiety comprising from 1 to 100 carbon atoms, preferentially from 1 to 40 carbon atoms, more preferentially from 3 to 20 carbon atoms,

Examples of trimeric MoDTC compounds include the compounds and the preparation methods thereof, as described in patent application WO-98-26030.

Preferentially, the MoDTC compound used in the lubricant composition according to the invention is a dimeric MoDTC compound. Examples of dimeric MoDTC compounds include compounds and preparation methods thereof, as described in patent application EP-0757093.

The dimeric MoDTC compounds generally have the formula (A):

- wherein:
  - R¹, R², R³and R⁴, either identical or different, independently represent a hydrocarbon moiety chosen from alkyl, alkenyl, aryl, cycloalkyl and cycloalkenyl moieties;
  - X¹, X², X³and X⁴, either identical or different, independently represent an oxygen atom or a sulfur atom.

Advantageously, R¹, R², R³and R⁴, which can be either identical or different, independently represent an alkyl moiety comprising from 4 to 18 carbon atoms or an alkenyl moiety comprising from 2 to 24 carbon atoms.

Also advantageously, X¹, X², X³and X⁴can be identical and represent a sulfur atom or else same can be identical and represent an oxygen atom. Also advantageously, X¹and X²can represent a sulfur atom and X³and X⁴can represent an oxygen atom. Also advantageously, X¹and X²can represent an oxygen atom and X³and X⁴can represent a sulfur atom.

The MoDTC compound with the formula (A) can also be chosen from at least one symmetrical MoDTC compound, at least one asymmetrical MoDTC compound and combinations thereof. Symmetrical MoDTC compound refers to a MoDTC compound with the formula (A) wherein the moieties R¹, R², R³and R⁴are identical. Asymmetric MoDTC compound refers to a MoDTC compound with the formula (A) wherein the moieties R¹and R²are identical, the moieties R³and R⁴are identical and the moieties R¹and R²are different from the moieties R³and R⁴.

Advantageously, the lubricant composition according to the invention can comprise a mixture of at least one symmetrical MoDTC compound and at least one asymmetrical MoDTC compound. More advantageously, identical R¹and R², then represent an alkyl moiety comprising from 5 to 15 carbon atoms and identical R³and R⁴different from R¹and R², represent an alkyl moiety comprising from 5 to 15 carbon atoms. Preferentially, identical R¹and R², represent an alkyl moiety comprising from 6 to 10 carbon atoms and R³and R⁴represent an alkyl moiety comprising from 10 to 15 carbon atoms.

Similarly, identical R¹and R², can represent an alkyl moiety comprising from 10 to 15 carbon atoms and R³and R⁴can represent an alkyl moiety comprising from 6 to 10 carbon atoms.

Also, identical R¹and R², R³and R⁴, can represent an alkyl moiety comprising from 5 to 15 carbon atoms, preferentially from 8 to 13 carbon atoms.

Advantageously, the MoDTC compound is chosen from the compounds with the formula (A) wherein:

- X¹and X²represent an oxygen atom,
- X³and X⁴represent a sulfur atom,
- R¹represents an alkyl moiety comprising from 8 carbon atoms or an alkyl moiety comprising 13 carbon atoms,
- R²represents an alkyl moiety comprising from 8 carbon atoms or an alkyl moiety comprising 13 carbon atoms,
- R³represents an alkyl moiety comprising from 8 carbon atoms or an alkyl moiety comprising 13 carbon atoms,
- R⁴represents an alkyl moiety comprising from 8 carbon atoms or an alkyl moiety comprising 13 carbon atoms,

Thereby, advantageously, the MoDTC compound can be chosen from the compounds with the formula (A1)

- wherein R¹, R², R³and R⁴are as defined for the formula (A).

Advantageously, the MoDTC compound is a mixture:

- of an MoDTC compound with the formula (A1) wherein R¹, R², R³and R⁴represent an alkyl moiety comprising 8 carbon atoms,
- of a MoDTC compound with the formula (A1) wherein R¹, R², R³and R⁴represent an alkyl moiety comprising 13 carbon atoms, and
- of a MoDTC compound with the formula (A1) wherein R¹and R²represent an alkyl moiety comprising 13 carbon atoms and R³and R⁴represent an alkyl moiety comprising 8 carbon atoms, and/or
- of a MoDTC compound with the formula (A1) wherein R¹and R²represent an alkyl moiety comprising 8 carbon atoms and R³and R⁴represent an alkyl moiety comprising 13 carbon atoms.

The ratio (S/O) between the number of sulfur atoms and the number of oxygen atoms of the MoDTC compound can generally vary from (1/3) to (3/1).

Particular examples of MoDTC compounds include the products Molyvan L®, Molyvan 807® or Molyvan 822® sold by the R. T. Vanderbilt Company or the products Sakuralube 200®, Sakuralube 165®, Sakuralube 525® or Sakuralube 600® sold by the company Adeka.

The lubricant composition used according to the invention can also be used with an organomolybdenum compound chosen among the MoDTC compounds described in the patent application WO-2012-141855.

Similarly, same can be used with a complex organomolybdenum compound or a MoDTP compound chosen among the compounds described in the patent applications WO-2014-076240 and FR-3014898.

Advantageously, the MoDTP compound is chosen among the compounds with the formula (B)

- wherein R⁵, R⁶, R⁷and R⁸, which can be ether identical or different, independently represent a hydrocarbon moiety chosen among alkyl, alkenyl, aryl, cycloalkyl or cycloalkenyl moieties.

Examples of MoDTP compounds include the product Molyvan L® sold by R. T. Vanderbilt Company or the products Sakura-lube 300® or Sakura-lube 310G® sold by Adeka.

The invention can also be implemented with a sulfur and phosphorus free organomolybdenum compound complex. The sulfur and phosphorus free organomolybdenum complex can be prepared using amide ligands, which are mainly prepared by reacting a source of molybdenum, e.g. molybdenum trioxide, with an amine and fatty acid derivative having e.g. 4 to 28 carbon atoms, preferentially from 8 to 18 carbon atoms. Examples of fatty acids are derived from vegetable or animal oils. Such organomolybdenum complex can be prepared according to the methods described in the patents U.S. Pat. No. 4,889,647, EP-0546357, U.S. Pat. No. 5,412,130, EP-1770153. A preferred organomolybdenum complex is obtained by the reaction between:

- (i) a fatty acid or fatty substance of the mono-, di- or tri-glyceride type,
- (ii) a source of amines with the formula (C):

- wherein R⁹and R¹⁰, either identical or different, independently represent an OH or NH₂moiety,
- (iii) a source of molybdenum chosen from molybdenum trioxide or molybdates, preferentially ammonium molybdate, in a sufficient amount for providing from 0.1 to 30%, preferentially from 2 to 8.5%, by weight of molybdenum with respect to the weight of the complex.

Preferentially, the organomolybdenum complex comprises at least one compound with the formula (D) or with the formula (E) or a mixture thereof:

- wherein:
  - L¹and L², either identical or different, independently represent O or NH,
  - Q¹and Q², either identical or different, independently represent a linear or branched, saturated or unsaturated alkyl moiety comprising from 3 to 30 carbon atoms, preferentially from 3 to 20 carbon atoms, advantageously from 7 to 17 carbon atoms.

Such organomolybdenum complex can be prepared by the reaction between:

- (i) a fatty acid or fatty substance of the mono-, di- or tri-glyceride type,
- (ii) diethanolamine or 2-(2-aminoethyl)aminoethanol,
- (iii) a source of molybdenum chosen from molybdenum trioxide or molybdates, preferentially ammonium molybdate, in a sufficient amount for providing 0.1 to 20% by weight of molybdenum with respect to the weight of complex.

More preferentially, the organomolybdenum complex comprises at least one compound with the formula (D1) or with formula (D2) or a mixture thereof:

Wherein Q¹independently represents an either linear or branched alkyl moiety, either saturated or unsaturated, comprising from 3 to 30 carbon atoms, preferentially from 3 to 20 carbon atoms, more preferentially from 7 to 17 carbon atoms,

Boron-Containing Dispersant(s)

The lubricant composition according to the invention further comprises one or several boron-containing dispersant(s), such that the amount of boron in the lubricant composition ranges from 10 to 300 ppm by weight, preferentially from 20 to 300 ppm by weight, with respect to the total weight of the lubricant composition.

The amount of boron in the lubricant composition according to the invention can be measured according to the standard ASTM D 5185.

According to one embodiment, the lubricant composition further comprises from 0.01% to 10% by weight, preferentially from 0.01% to 5% by weight, boron-containing dispersant(s), with respect to the total weight of the composition.

Preferentially, the boron-containing dispersant(s) are chosen from boron-containing succinimides, typically from boron-containing polyisobutenes succinimides.

Base Oil(s)

The lubricant composition according to the invention comprises one or several base oils. The base oil can be chosen from many oils. The base oil in the lubricant composition of the invention can be chosen in particular from among mineral or synthetic origin oils belonging to groups I to V according to the classes defined by the API classification (or the equivalents thereof according to the ATIEL classification (Table A) or the mixtures thereof.

TABLE 1 Viscosity Concentration of Sulfur index saturated [oils] concentration (VI) Group I <90% >0.03% 80 ≤ VI < 120 Mineral oils Group II ≥90% ≤0.03% 80 ≤ VI < 120 Hydrocracked oils Group III ≥90% ≤0.03% ≥120 Hydro-isomerized or hydrocracked oils Group IV polyalphaolefines (PAO) Group V esters and other bases not included in groups I to IV

The useful mineral base oils according to the invention include any type of base oil obtained by atmospheric distillation and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, deasphalting, solvent dewaxing, hydrotreatment, hydrocracking, hydroisomerization and hydrofinishing. Mixtures of synthetic and mineral oils can also be used.

There is generally no limitation with regard to the use of different lubricant bases for producing the lubricant compositions according to the invention, except that the same should have properties, in particular in terms of viscosity, viscosity index, concentration of sulfur, resistance to oxidation, suitable for use for engines.

The base oils of the lubricant compositions according to the invention can be further chosen from among synthetic oils, such as certain esters of carboxylic acids and alcohols, polyalkylene glycols (PAG), and among polyalphaolef ins.

According to one embodiment, the lubricant composition according to the invention comprises at least one oil from Group II and/or at least one oil from Group III.

Typically, the base oil(s) represent at least 50% by weight, preferentially at least 60% by weight, preferentially yet at least 70% by weight, even more preferentially at least 75% by weight, of the total weight of the lubricant composition.

Thereby, according to one embodiment, the lubricant composition comprises from 50% to 99.89% by weight, preferentially from 70% to 99.5% by weight, more preferentially from 80% to 99% by weight of base oil(s), preferentially including: at least one oil from Group II and/or at least one oil from Group III and/or at least one oil from Group IV and/or at least one oil from Group V.

Other Additive(s)

According to one particular embodiment, the lubricant composition according to the invention further comprises one or a plurality of other additives.

The other preferred additives for the lubricant composition according to the invention are chosen among detergent additives, anti-wear additives, friction modifier additives with the exception of molybdenum friction modifiers, extreme pressure additives, dispersants distinct from the boron dispersants defined hereinabove, pour point depressants, viscosity index improvers, defoamers, thickeners and mixtures thereof.

Preferentially, where present, additives chosen among detergent additives, anti-wear additives, friction modifier additives except molybdenum friction modifiers, extreme pressure additives, dispersants distinct from the boron dispersants defined hereinabove, pour point depressants, viscosity index improvers, defoamers, thickeners and mixtures thereof represent up to 20% by weight, preferentially from 0.1% to 15% by weight, more preferentially from 1% to 10% by weight, of the total weight of the lubricant composition.

According to one embodiment, the lubricant composition further comprises at least one detergent. Detergent additives generally reduce the formation of deposits on the surface of metal parts, by dissolving oxidation and combustion by-products. The detergent additives which can be used in the lubricant composition according to the invention are generally known to a person skilled in the art. The detergent additives can be anionic compounds comprising a long lipophilic hydrocarbon chain and a hydrophilic head. The associated cation can be a metal cation of an alkali or alkaline earth metal. Detergent additives are preferentially chosen from alkali metal salts or alkaline-earth metal salts of carboxylic acid, sulfonates, salicylates, naphthenates, as well as phenate salts. The alkali metals and alkaline earth metals are preferentially calcium, magnesium, sodium or barium. Such metal salts generally include the metal in a stoichiometric amount or in an excess amount, i.e. in a concentration greater than the stoichiometric amount. Same are then over based detergents; the metal in excess which gives the over based character to the detergent additive is generally in the form of an oil-insoluble metal salt, e.g. a carbonate, a hydroxide, an oxalate, an acetate, a glutamate, preferentially a carbonate.

According to a particular embodiment, the lubricant composition comprising at least one detergent chosen from calcium detergents, magnesium detergents, and mixtures thereof. According to one embodiment, the lubricant composition according to the invention comprises at least one calcium detergent and at least one magnesium detergent.

Advantageously, the lubricant composition according to the invention can comprise from 2 to 4% by weight of detergent additive(s) with respect to the total weight of lubricant composition.

Advantageously, the lubricant composition according to the invention can further comprise at least one boron-free dispersing agent. The boron-free dispersing agent can be chosen from among Mannich bases, succinimides and derivatives thereof. According to one embodiment, the boron-free dispersant(s) can be chosen from boron-free polyisobutene succinimide, and mixtures thereof.

Further advantageously, the lubricant composition according to the invention can comprise from 0.2% to 10% by weight of boron-free dispersing agent with respect to the total weight of lubricant composition.

The lubricant composition used according to the invention can comprise at least one additive improving the pour point or PPD (pour point depressant or agent reducing the pour point). By slowing down the formation of paraffin crystals, the pour point depressants generally improve the behavior, under cold conditions, of the lubricant composition according to the invention. Examples of pour point depressant additives include alkyl polymethacrylates (different from the copolymer of the invention), polyacrylates (different from the copolymer of the invention), polyarylamides, polyalkylphenols, polyalkylnaphthalenes, alkyls polystyrenes.

The lubricant composition according to the invention can also comprise at least one anti-wear additive, at least one extreme pressure additive or mixtures thereof. In a preferred way, the lubricant composition according to the invention comprises at least one anti-wear additive.

Anti-wear additives and extreme pressure additives protect surfaces subject to friction by forming a protective film adsorbed on the surfaces. There is a wide variety of anti-wear additives. Preferentially, for the lubricating composition used according to the invention, the anti-wear additives are chosen from phosphorus-sulfur additives such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates or ZnDTP. Preferred compounds have the formula Zn((SP(S)(OR^a)(OR^b))₂, wherein R^aand R^b—either identical or different—independently represent an alkyl moiety, preferentially an alkyl moiety including from 1 to 18 carbon atoms. Amine phosphates are also anti-wear additives which can be used in the lubricant composition used according to the invention. However, the phosphorus provided by such additives can act as a poison in the catalytic systems of cars since same generate ash. Such effects can be minimized by partially substituting the amine phosphates with additives which do not bring phosphorous, such as e.g. polysulf ides, in particular sulfur-containing olefins.

Advantageously, the lubricant compositions according to the invention can comprise from 0.01 to 6% by weight, preferentially from 0.05 to 4% by weight, more preferentially from 0.1 to 2% by weight with respect to the total weight of lubricant composition, of anti-wear additives and of extreme pressure additives.

Advantageously, the lubricant composition according to the invention can comprise at least one friction modifying additive different from the molybdenum friction modifier defined in the present invention. The friction modifier additives can be chosen from compounds providing metallic elements and ashless compounds. Compounds providing metal elements include complexes of transition metals such as Sb, Sn, Fe, Cu, Zn the ligands of which can be hydrocarbon compounds comprising oxygen, nitrogen, sulfur or phosphorus atoms. Ashless friction modifier additives are generally of organic origin and can be chosen from fatty acid and polyol monoesters, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, fatty epoxide borates; fatty amines acid or fatty acid glycerol esters. According to the invention, fatty compounds comprise at least one hydrocarbon moiety comprising from 10 to 24 carbon atoms.

Advantageously, the lubricant composition according to the invention can comprise from 0.01% to 2% by weight or from 0.01% to 5% by weight, preferentially from 0.1% to 1.5% by weight or from 0.1% to 2% by weight with respect to the total weight of the lubricant composition, of friction modifier additive.

Advantageously, the lubricant composition according to the invention can comprise at least one antioxidant additive. The antioxidant additive generally delays the degradation of the lubricant composition in service. Such degradation is most often appears in the formation of a deposit, in the presence of sludge or in an increase in the viscosity of the lubricant composition. Antioxidant additives in particular act as radical inhibitors or destroyers of hydroperoxides. The antioxidant additives commonly used include phenolic antioxidants, amine antioxidant additives, phosphosulfur antioxidant additives. Some of such antioxidant additives, e.g. phosphosulfur antioxidant additives, can generate ashes. The phenolic antioxidant additives can be ash-free or in the form of neutral or basic metal salts. The antioxidant additives can in particular be chosen from sterically hindered phenols, sterically hindered phenol esters and sterically hindered phenols comprising a thioether bridge, diphenylamines, diphenylamines substituted with at least one C₁-C₁₂alkyl moiety, N,N′-dialkyl-aryl-diamines and mixtures thereof. Preferentially, according to the invention, the sterically hindered phenols are chosen from compounds comprising a phenol moiety of which at least one of the carbons neighboring the carbon atom bearing the alcohol function is substituted by at least one C₁-C₁₀alkyl moiety, preferentially a C₁-C₆alkyl moiety, preferentially a C₄alkyl moiety, preferentially a tert-butyl moiety. Amine compounds are another class of antioxidant additives which can be used, if appropriate, in combination with phenolic antioxidant additives. Examples of amine compounds are aromatic amines, e.g. aromatic amines with the formula NR^cR^dR^ewherein R^crepresents an aliphatic moiety or a possibly substituted aromatic moiety, R^drepresents a possibly substituted aromatic moiety, R^erepresents a hydrogen atom, an alkyl moiety, an aryl moiety or a moiety with the formula R^fS(O)_zR^gwherein R^frepresents an alkylene or an alkenylene moiety, R^grepresents an alkyl moiety, an alkenyl moiety or an aryl moiety and z is 0, 1 or 2. Sulfur alkyl phenols or the alkali or alkaline-earth metal salts thereof can further be used as antioxidant additives. Another class of antioxidant additives is the class of copper compounds, e.g. copper thio- or dithio-phosphate, copper salts and carboxylic acid salts, copper dithiocarbamates, copper sulfonates, copper phenates, copper acetylacetonates. Copper I and II salts, succinic acid salts or succinic anhydride salts can further be used. The lubricant composition used according to the invention can comprise any type of antioxidant known to a person skilled in the art. Advantageously, the lubricant composition comprises at least one ash-free antioxidant additive. Further advantageously, the lubricant composition used according to the invention comprises from 0.5 to 2% by weight with respect to the total weight of the composition, of at least one antioxidant additive.

Advantageously, the lubricant composition can also comprise at least one polymer improving the viscosity index, different from the copolymer defined in the present invention. Examples of an additional polymer improving the viscosity index include hydrogenated or non-hydrogenated polymer esters, homopolymers or copolymers of styrene, of butadiene, and of isoprene, polymethacrylates (PMA). Further advantageously, the lubricant composition according to the invention can comprise from 0.1 to 15% by weight, with respect to the total weight of lubricant composition, of polymer improving the viscosity index, different from the copolymer defined in the present invention.

Typically, the lubricant composition according to the invention has a kinematic viscosity at 100° C. ranging from 3.8 mm²/s to 21.9 mm²/s. The kinematic viscosity can be measured according to the standard ASTM D445.

Applications

The invention further relates to the use, in a lubricant composition comprising a base oil, one or a plurality of molybdenum friction modifiers and one or a plurality of boron dispersants, of a copolymer as defined hereinabove, for improving the cold stability of said lubricant composition.

In particular, the lubricant composition comprising the base oil, the molybdenum friction modifier(s), the boron dispersant(s) and the copolymer of the invention exhibits improved cold stability compared to the composition free of the copolymer.

“Cold stability”, as defined by the invention, means the ability of a lubricant composition to keep the physical homogeneity thereof during prolonged storage, in particular for several weeks, at a low temperature, in particular at a temperature of 0° C. More particularly, a composition having good cold stability does not have any problems of sedimentation or deposit formation during prolonged storage at low temperature.

The cold stability of a lubricant composition can typically be evaluated as follows:

50 mL of the lubricant composition to be tested is poured into a test tube before being placed in a refrigerated chamber.

The state of the composition is then evaluated visually depending on the storage time.

The following rating is used:

- OK: the state of the composition is unchanged. No trace of deposit is observed,
- TRACE: the presence of slight traces of deposit is observed,
- DEPOSIT: deposit formation is observed,
- CLOUDY: The lubricant composition is cloudy due to the formation of a large amount of deposits.

According to one embodiment, the copolymer is as defined above within the framework of the lubricant composition according to the invention.

According to one embodiment, the molybdenum friction modifier(s) are as defined above within the framework of the lubricant composition according to the invention.

According to one embodiment, the boron dispersant(s) are as defined above within the framework of the lubricant composition according to the invention.

According to one embodiment, the base oil or oils are as defined hereinabove.

According to one embodiment, the lubricant composition is as defined hereinabove, after addition of the copolymer.

According to one embodiment, the copolymer is used in a proportion of from 0.1 to 10% by weight of dry matter, preferentially from 0.5 to 5% by weight of dry matter, more preferentially from 0.8 to 3% by weight of dry matter, with respect to the total weight of the lubricant composition (after adding the copolymer).

The invention further relates to the use of the lubricant composition according to the invention for lubricating the parts of an engine such as an engine of a motor vehicle.

The invention further relates to a method for lubricating at least one part of an engine, preferentially a vehicle engine, comprising bringing at least one part of the engine into contact with the lubricant composition according to the invention.

The invention further relates to a method for reducing friction occurring within an engine, said method comprising the use of a combination of a copolymer as defined hereinabove, a molybdenum friction modifier and a boron dispersant in a lubricant composition comprising a base oil.

The invention further relates to a method for improving the fuel economy (FE) properties of a lubricant composition, said method comprising the use of a combination of a copolymer as defined hereinabove, a molybdenum friction modifier and a boron dispersant in a lubricant composition comprising a base oil.

The invention further relates to a method for improving the cold stability properties (typically at 0° C.) of a lubricant composition, said method comprising the use of a combination of a copolymer as defined hereinabove, a molybdenum friction modifier and of a boron dispersant in a lubricant composition comprising a base oil.

The molybdenum friction modifier, the boron dispersant and the copolymer are then supplied either separately or in the form of a combination within the lubricant composition.

In the uses and methods of the invention, the copolymer, the molybdenum friction modifier, the boron dispersant and, more generally, the lubricant composition which results therefrom can have one or a plurality of the features defined hereinabove within the framework of the lubricant composition according to the invention.

The particular, advantageous or preferred features of the combined use according to the invention define particular, advantageous or preferred combinations which can be used according to the invention.

The different aspects of the invention can be illustrated by the examples which follow.

Example 1: Preparation of Lubricant Compositions

The lubricant compositions are prepared by mixing the compounds described in Table 2, at a temperature on the order of 60° C. The percentages indicated correspond to percentages by weight with respect to the total weight of the composition. Composition CL1 is a composition according to the invention and composition CC1 is a comparative composition outside of the invention.

TABLE 2 CL1 CC1 Base oils (% weight) 83.9 83.9 Copolymer 1 according to the invention (% dry 5.0 — weight) Copolymer 2 outside the invention (% dry weight) — 5.0 Additive package (% weight) 10.1 10.1 including 39 39 boron content (ppm by weight) Additive lowering the pour point (% weight) 0.2 0.2 Friction modifiers: Mo-DTC (Sakuralube 525 ® 0.8 0.8 from Adeka) (% weight) including 950 950 molybdenum content (ppm by weight)

Copolymer 1 (according to the invention) is as defined in US 2017/0009177 A1.

Copolymer 2 (outside the invention) is as defined in WO 2012/081180 A1.

The additive package includes a calcium detergent, a magnesium detergent, and a boron succinimide dispersant.

Example 2: Evaluation of the Friction Performance

The capacity of the lubricant compositions prepared hereinabove to reduce friction occurring in an engine is evaluated as follows:

The test is carried out using a Nissan MR20DD engine, with a power is of 108 kw at 5600 rpm, driven by an electric generator imposing a speed of rotation comprised between 550 and 4400 rpm whereas a torque sensor is used for measuring the friction torque generated by the movement of the parts in the engine. The friction torque induced by the lubricant composition to be tested is compared, for each engine speed and for each average torque at each temperature, with same induced by the reference lubricant composition (SAE 0W16) which was evaluated before and after the lubricant composition to be tested.

The higher the value of the gain in friction, the more the lubricant composition reduces the friction occurring in the engine.

The conditions for the test are as follows.

The tests should be carried out in the following sequence:

- rinsing the engine with a lubricating oil detergent additive comprising one rinse, followed by two rinses with a reference lubricant composition of grade 0W-12 comprising 81.7% by weight of base oil, 17.8% by weight of usual additives (4.4% viscosity index improver additive, 0.5% oxidizing additive, 0.20% additive for lowering the pour point and 12.7% of a pack of additives), and 0.05% by weight of molybdenum dithiocarbarmate (MoDTC), with respect to the total weight of the base oil;
- measurement of the friction torque at the two different temperatures indicated hereinbelow, on the engine using the reference lubricant composition;
- rinsing the engine with a detergent additive for lubricating oil comprising one rinse, followed by two rinses with a lubricant composition to be evaluated;
- measurement of the friction torque at two different temperatures on the engine, using the lubricant composition to be evaluated;
- rinsing the engine with a lubricating oil detergent additive comprising one rinse, followed by two rinses with the reference lubricant composition; and
- measurement of the friction torque at the two different temperatures indicated below, on the engine using the reference lubricant composition.

The speed ranges, the speed variation and the temperature were chosen in agreement with Nissan, so as to be representative of the WLTC cycle.

The implemented instructions are:

- Water temperature at the engine output: 50° C./80° C.+/−0.5° C.
- Oil temperature ramp: 50° C./80° C.+/−0.5° C.

The results obtained are presented in Table 3.

TABLE 3 CL1 CC1 Friction decrease 1.4% 1.2% T = 50° C. Friction decrease 1.8% 1.4% T = 80° C.

The lubricant composition according to the invention CL1 has a decrease in friction, measured at 50° C. and 80° C., greater than same of the comparative composition CC1. The composition CL1 according to the invention thus reduces more significantly the friction occurring in an engine, compared with the comparative composition CC1. In particular, the copolymer of the invention reduces friction occurring inside an engine.

A person skilled in the art knows that the reduction of friction occurring in the engine has a direct impact on the fuel consumption of the engine: the less friction there is, the less fuel the engine consumes. Thereby, the copolymer defined in the invention improves the FE properties of the lubricant composition.

Example 3: Cold Stability Evaluation

The cold stability of the lubricant compositions prepared hereinabove is evaluated as follows:

50 mL of the lubricant composition to be tested is poured into a test tube before being placed in a refrigerated chamber.

The state of the composition is then evaluated visually depending on the storage time.

The following rating is used:

- OK: the state of the composition is unchanged. No trace of deposit is observed,
- TRACE: the presence of slight traces of deposit is observed,
- DEPOSIT: deposit formation is observed,
- CLOUDY: The lubricant composition is cloudy due to the formation of a large amount of deposits.

The results obtained are presented in Table 4.

TABLE 4 CL1 CC1 9 days at 0° C. OK Deposits 7 weeks at 0° C. OK Deposits

The lubricant composition according to the invention CL1 has better cold stability than the comparative composition CC1. In particular, the composition according to the invention is stable even after storage for 7 weeks at 0° C. The copolymer defined in the invention thus leads to improving the cold properties of the lubricant composition.

Claims

1. A lubricant composition comprising:

at least one base oil,

at least one friction modifier comprising molybdenum, such that the amount of molybdenum in the lubricant composition ranges from 100 ppm to 1,500 ppm by weight, with respect to the total weight of the lubricant composition,

at least one boron-containing dispersant, such that the amount of boron in the lubricant composition ranges from 10 ppm to 300 ppm, with respect to the total weight of the lubricant composition,

from 0.1% to 10% by weight of dry matter, with respect to the total weight of the lubricant composition, of a polymer comprising repeating units which could be obtained by polymerization of monomers (a) with the formula (I):

wherein:

R1 represents a hydrogen atom or a methyl moiety,

X1 represents a moiety chosen from: —O—, —O(AO)m, or —NH—, each moiety A independently representing a C2-C4 alkylene moiety and m represents an integer ranging from 0 to 10,

R2 is a polybutylene moiety, and

p is 0 or 1.

2. The lubricant composition according to claim 1, comprising:

at least 50% by weight, with respect to the total weight of the lubricant composition, of one or several base oils,

from 0.01% to 10% by weight, with respect to the total weight of the lubricant composition, of one or several friction modifiers comprising molybdenum, such that the amount of molybdenum in the lubricant composition ranges from 300 ppm to 1,000 ppm by weight, with respect to the total weight of the lubricant composition,

from 0.01% to 10% by weight, with respect to the total weight of the lubricant composition, of one or several boron-containing dispersants, such that the amount of boron in the lubricant composition ranges from 10 ppm to 300 ppm by weight, with respect to the total weight of the lubricant composition,

from 0.5% to 5% by weight of dry matter, with respect to the total weight of the lubricant composition, of a copolymer which can be obtained by copolymerization of monomers (a) with the formula (I) and monomers (b) with the formula (II):

wherein:

R3 represents a hydrogen atom or a methyl moiety,

X2 is a —O— or —NH— moiety,

R4 moieties independently represent a C2-C4 alkylene moiety,

R5 represents a C1-C8 alkyl moiety, and

q is an integer ranging from 1 to 20.

3. The lubricant composition according to claim 1, comprising:

at least 70% by weight, with respect to the total weight of the lubricant composition, of one or a plurality of base oils,

from 0.01% to 5% by weight, with respect to the total weight of the lubricant composition, of one or several friction modifiers comprising molybdenum, such that the amount of molybdenum in the lubricant composition ranges from 500 ppm to 1,000 ppm by weight, with respect to the total weight of the lubricant composition,

from 0.01% to 5% by weight, with respect to the total weight of the lubricant composition, of one or several boron-containing dispersants, such that the amount of boron in the lubricant composition ranges from 20 ppm to 300 ppm by weight, with respect to the total weight of the lubricant composition,

from 0.8% to 3% by weight of dry matter, with respect to the total weight of the lubricant composition, of a copolymer comprising, with respect to the total weight of the copolymer: from 1% to 50% by weight of units derived from monomers (a), and from 1% to 80% by weight of units derived from monomers (b).

4. The lubricant composition according to claim 1, having a kinematic viscosity at 100° C., measured according to ASTM D445, ranging from 3.8 mm2/s to 21.9 mm2/s.

5. The lubricant composition according to claim 1, wherein the friction modifier comprising molybdenum is an organomolybdenum compound.

6. The lubricant composition according to claim 1, wherein the boron dispersant is chosen from boron succinimides.

7. A use, in a lubricant composition comprising a base oil, one or several molybdenum friction modifiers and one or several boron dispersants, of a copolymer comprising repeating units which can be obtained by polymerizing monomers (a) with the formula (I):

wherein:

R1 represents a hydrogen atom or a methyl moiety,

X1 represents a moiety chosen from: —O—, —O(AO)m, or —NH—, each moiety A independently representing a C2-C4 alkylene moiety and m represents an integer from 0 to 10,

R2 is a polybutylene moiety, and

p is 0 or 1,

for improving the cold stability of said lubricant composition.

8. (canceled)

9. (canceled)

10. (canceled)

11. The lubricant composition according to claim 5, wherein the friction modifier comprising molybdenum is chosen from a molybdenum dithiocarbamate derivative (MoDTC), a molybdenum dithiophosphate derivative (MoDTP) or a sulfur-free molybdenum complex.

12. The lubricant composition according to claim 5, wherein the friction modifier comprising molybdenum is a molybdenum dithiocarbamate derivative (MoDTC).

13. The lubricant according to claim 6, wherein the boron dispersant is chosen from boron polyisobutene succinimides.

14. A method for lubricating at least one part of an engine, said method comprising bringing at least one part of the engine into contact with a lubricant composition according to claim 1.

15. The method according to claim 14, for reducing friction occurring within said engine.

16. A method for improving the fuel economy (FE) properties and/or the cold stability properties of a lubricant composition, said method comprising adding to said lubricant composition a combination of:

a) at least one polymer comprising repeating units which could be obtained by polymerization of monomers (a) with the formula (I):

wherein: R1 represents a hydrogen atom or a methyl moiety, X1 represents a moiety chosen from: —O—, —O(AO)m, or —NH—, each moiety A independently representing a C2-C4 alkylene moiety and m represents an integer ranging from 0 to 10,

R2 is a polybutylene moiety, and

p is 0 or 1,

b) at least one friction modifier comprising molybdenum, such that the amount of molybdenum in the lubricant composition ranges from 100 ppm to 1,500 ppm by weight, with respect to the total weight of the lubricant composition, and

c) at least one boron-containing dispersant, such that the amount of boron in the lubricant composition ranges from 10 ppm to 300 ppm, with respect to the total weight of the lubricant composition.