EP4695356A1

EP4695356A1 - Lubrication system for an electric or hybrid vehicle

Info

Publication number: EP4695356A1
Application number: EP24716190.4A
Authority: EP
Inventors: Christine HAMON; Gaetano CALVARUSO
Original assignee: Syensqo Specialty Polymers Italy SpA
Current assignee: Syensqo Specialty Polymers Italy SpA
Priority date: 2023-04-14
Filing date: 2024-04-09
Publication date: 2026-02-18
Also published as: CN121195046A; WO2024213537A1

Abstract

The present invention relates to a lubrication system for a propulsion system of an electric or hybrid vehicle said lubrication system comprising a (per)fluoropolyether polymer as base oil and at least one thickener.

Description

Lubrication system for an electric or hybrid vehicle

Cross-reference to related patent application(s)

[0001] This application claims priority filed on 14 April 2023 in EUROPE with Nr 23168083.6, the whole content of this application being incorporated herein by reference for all purposes.

Technical field

[0002] The present invention relates to the field of lubrication for a propulsion system of an electric or hybrid vehicle. In particular it relates to a lubrication system comprising a (per)fluoropolyether polymer as base oil and at least one thickener.

Background

[0003] The invention is directed to the use of a composition comprising a (per)fluoropolyether polymer as base oil and at least one aromatic polymer thickener as a lubricant in a propulsion system of an electric or hybrid vehicle.

[0004] The composition provides excellent lubrication properties even at the very high rotational speed that characterise the propulsion and transmission systems in electric or hybrid vehicles.

[0005] The changes in the international standards for the reduction of CO2 emissions, but also for the reduction of energy consumption, has driven motor vehicle constructors toward proposing alternative solutions to combustion engines.

[0006] One of the solutions identified by motor vehicle constructors consists in replacing combustion engines with electric motors.

[0007] For the purposes of the present invention, the term "electric vehicle" means a vehicle comprising an electric motor as sole means of propulsion, as opposed to a hybrid vehicle which comprises a combustion engine and an electric motor as combined means of propulsion.

[0008] For the purposes of the present invention, the term "propulsion system" means a system comprising the mechanical parts required for propelling an electric vehicle. The propulsion system thus more particularly encompasses an electric motor comprising the rotor-stator assembly, power electronics (dedicated to regulating the speed), a transmission and a battery.

[0009] In general, it is necessary to use, in electric or hybrid vehicles, compositions to meet the constraints of lubricating the various parts of the propulsion system recalled above.

[0010] Lubricant compositions, also referred to as "lubricants", are commonly used in propulsion systems such as electric motors for the purposes of reducing the friction forces between the various metal parts in motion in the transmission parts. They are also effective for preventing premature wear or even damage of these parts, and in particular of their surface.

[0011] To do this, a lubricant composition is conventionally composed of one or more base oils which are generally combined with several additives intended for stimulating the lubricant performance of the base oils, for instance thickeners.

[0012] To operate at high temperature, the thickening additive should have excellent thermal and chemical stability.

[0013] The use of polymers that are solid at room temperature and have a melting point higher than 150°C as thickeners in lubricant compositions, was disclosed for example in WO 2007/082829A1 (Solvay Solexis S.p.A.). This patent application discloses the use of polymers containing at least one aromatic ring in their backbone as additives to stabilize perfluoropolyether oils. The compositions disclosed in this patent application comprised aromatic polymer powder having an average size preferably between 0.1 pm and 1 ,000 pm. Preferred embodiment comprised, in addition to said aromatic polymer powder, PTFE powder.

[0014] (Per)fluoropolyether (PFPE) lubricants, i.e. lubricants comprising a perfluorooxyalkylene chain, that is to say a chain comprising recurring units having at least one ether bond and at least one fluorocarbon moiety, are endowed with high thermal and chemical resistance, so they are useful in cases of applications characterized by harsh conditions (very high temperatures, presence of oxygen, use of aggressive chemicals and radiations, etc.). They have been known for a long time and are used to formulate lubricants that function for long periods of time in extreme environments.

Summary of the invention

[0015] The Applicant noted that the performances of the aromatic polymer powders used in the art are no longer suitable to meet the ever increasing requirements of specialty industries such as the requirements of electric or hybrid vehicles.

[0016] Hence, the Applicant faced the problem of providing a composition suitable to lubricate electrical components suitable for use in different applications and industries, such as in particular electric, electronic and automotive industries. Indeed, the Applicant is aware that nowadays the electrical erosion in rolling bearings is a challenge for e-mobility due to the very high speed of rotation, higher acceleration and high heating typical of electrical motors. Also, the lubricants in electric vehicles are replaced less frequently compared to internal combustion engines. Hence, the lubricants for electric motors should be able to last longer.

[0017] The Applicant thus faced the problem of providing lubricants for electric motors in electric vehicles or hybrid vehicles that can maintain their viscosity at the high temperatures generated by the electric motors. Indeed, compared to internal combustion engines, electric motors generates more heat, which results in the quicker break down of the lubricant.

[0018] The Applicant has surprisingly found compositions that meet the above mentioned requirements and can be hence used as such as lubricant for electrical and electronic components, including electrical connectors, switchgears and circuit breakers, as well as for mechanical components, in particular suitable for use in the automotive industry, including to lubricate parts used in electric or hybrid vehicles, such as ball bearings.

Disclosure of the invention

[0019] In the present application:

- the use of parentheses around symbols or numbers identifying the formulae, for example in expressions like “polymer (P)”, etc., has the mere purpose of better distinguishing the symbol or number from the rest of the text and, hence, said parenthesis can also be omitted;

- the acronym “PFPE” stands for "(per)fluoropolyether” and, when used as substantive, is intended to mean either the singular or the plural form, depending on the contex-t;

- the prefix "(per)" in the term "(per)fluoropolyether” means that the polyether can be fully or partially fluorinated.

[0020] In a first aspect, the present invention relates to a method for lubricating at least one component in the propulsion system of an electric or hybrid vehicle, said method comprising applying a composition as detailed hereafter to at least a part of such a component.

[0021 ] The component in the propulsion system of an electric or hybrid vehicle may be an electrical or electronic component or a mechanical component.

[0022] In a second aspect, the present invention relates to a propulsion system of an electric or hybrid vehicle comprising the lubricant composition as detailed herafter.

[0023] The first object of the invention is thus a method for lubricating at least one component in the propulsion system of an electric or hybrid vehicle, said method comprising applying to at least a part of such a component a composition, hereinafter referred to as composition (COMP), comprising:

(A) a (per)fluoropolyether polymer-base oil [PFPE base oil]; and

(B) from 0.1 % to 45.0% by weight, preferably from 1 .0% to 40.0% by weight, based on 100% by weight of said composition, of at least one aromatic polymer thickener, hereinafter [Polymer AP], [0024] Surprisingly, the Applicant found that composition (COMP) has excellent stability over time even at high speeds or rotation.

[0025] Preferably, the [PFPE base oil] is a (per)fluoropolyether polymer [PFPE polymer] comprising a linear or branched (per)fluoropolyether chain [PFPE chain] having two chain ends bonded to opposite sites of said chain, both chain ends comprising a linear or branched perfluorinated alkyl chain having from 1 to 6 carbon atoms, said polymer having a number average molecular weight from 500 to 100000, preferably from 2000 to 50000 as measured by NMR.

[0026] Preferably, each of the PFPE chains mentioned above in the PFPE polymer is a partially or fully fluorinated chain [chain (Rf)] comprising, preferably consisting of, repeating units R°, said repeating units being independently selected from the group consisting of:

(i) -CFXO-, wherein X is F or CF3;

(ii) -CFXCFXO-, wherein X, equal or different at each occurrence, is F or CF3, with the proviso that at least one of X is -F;

(iii) -CF2CF2CW2O-, wherein each of W, equal or different from each other, are F, Cl, H;

(iv) -CF2CF2CF2CF2O-;

(v) -(CF2)_W-CFZ-O- wherein w is an integer from 0 to 3 and Z is a group of general formula -O-R(f._a)-Y, wherein R<f._a) is a fluoropolyoxyalkene chain comprising a number of repeating units from 0 to 10, said recurring units being chosen among the followings : -CFXO- , -CF2CFXO-, -CF2CF2CF2O-, - CF2CF2CF2CF2O-, with each of each of X being independently F or CF3 and Y being a C1-C3 perfluoroalkyl group.

[0027] Preferably, chain (Rf) complies with the following formulae (Rf-I) and (Rf-I I): (Rf-I)

-[(CFX¹O)_gi(CFX²CFX³O)_g2(CF2CF2CF2O)_g3(CF2CF2CF2CF₂O)_g4]- wherein

- X¹ is independently selected from -F and -CF3,

- X², X³, equal or different from each other and at each occurrence, are independently -F, -CF3, with the proviso that at least one of X is -F;

- g1 , g2, g3, and g4, equal or different from each other, are independently >0, such that g1 +g2+g3+g4 is in the range from 2 to 300, preferably from 10 to 250, even more preferably from 15 to 200; should at least two of g1 , g2, g3 and g4 be different from zero, the different recurring units are generally statistically distributed along the chain;

(Rf-ll)

-[(CFX¹O)_gi(CFX²CFX³O)_g2(CF2CF2CF2O)_g3(CF2CF2CF2CF₂O)_g4-

(CF(CF3)O)_g5(CF₂CF(CF3)O)_g6]- wherein

- X¹, X², X³ are as defined above;

- g1 , g2, g3, g4, g5 and g6, equal or different from each other, are independently >0, such that g1 +g2+g3+g4+g5+g6 is in the range from 2 to 300, preferably from 10 to 250, with the proviso that at least one of g5 and g6 are different from 0.

[0028] In a preferred embodiment, chain (Rf) complies with formula (Rf-I) above.

[0029] Preferably, the PFPE polymer has a viscosity higher than 10 mm²/s at 20°C, more preferably higher than 20 mm²/s at 20°C and even more preferably higher than 30 mm²/s at 20°C.

[0030] Preferably, the PFPE polymer has a viscosity lower than 2500 mm²/s at 20°C, and more preferably lower than 2000 mm²/s at 20°C.

[0031 ] Preferably, the PFPE polymer has a viscosity of 35 to 2000 mm²/s at 20°C, more preferably of 35 to 550 mm²/s at 20°C and even more preferably of 50 to 400 mm²/s at 20°C, in some instances of 60 to 350 mm²/s at 20°C.

[0032] Advantageously, the PFPE polymer has has a viscosity of 25 to 350 mm²/s at 20°C, more preferably of from 40 to 350 mm²/s at 20°C and even more preferably of from 60 to 300 mm²/s at 20°C.

[0033] The above viscosity of the PFPE copolymer according to the present invention was measured at 20°C according to ASTM D445.

[0034] Aromatic polymer thickener, [Polymer AP], is in the form of powder having an average particle size (dso) higher than 1 micrometer, more preferably higher than 2 micrometers, and still more preferably higher than 3 micrometers, as measured by laser diffraction particle size analysis as volume particle size distribution.

[0035] Preferably, [Polymer AP] is in the form of powder having a dso below 15 micrometers, more preferably below 12 micrometers, and still more preferably below 10 micrometers. Average particle size is measured by laser diffraction particle size analysis and refers to the volume particle size distribution.

[0036] Typically, [Polymer AP] has a melting point of at least 150°C.

[0037] Preferably, [Polymer AP] is in the form of powder having a dso measured by laser diffraction particle size analysis as volume particle size distribution, in the range from above 1 micrometer and up to 15 micrometers, and a surface area (determined by gas adsorption using the BET method according to ISO 9277) from 0.5 to less than 5 m²/g.

[0038] [Polymer AP] is present in composition (COMP) in an amount of 0.1 % to 45.0% by weight based on 100% by weight of the composition. [Polymer AP] is present in composition (COMP) in an amount of at least 1 .0 wt%, even 5.0 wt%. [Polymer AP] is present in composition (COMP) in an amount generally not exceeding 40.0 wt%, even 35.0 wt%.

[0039] [Polymer AP] is advantageously selected in the group comprising, preferably consisting of:

(a) poly(arylene sulfide) (PAS) polymer;

(b) poly(phenylene oxide) (PPO) polymer;

(c) poly(aryl ether ketone) (PAEK) polymer; and

(d) poly(aryl ether sulfone) (PAES) polymer.

[0040] Preferably, said (a) poly(arylene sulfide) (PAS) is a polymer comprising -(Ar-S)- recurring units, wherein Ar is an arylene group, also called herein recurring unit (RPAS).

[0041] The arylene groups of the PAS can be substituted or unsubstituted.

[0042] Additionally, said PAS can include any isomeric relationship of the sulfide linkages in polymer; e.g., when the arylene group is a phenylene group, the sulfide linkages can be ortho, meta, para, or combinations thereof. [0043] Preferably, said PAS polymer comprises at least 5, at least 10, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, at least 95, at least 98 mol.% of recurring units (RPAS), based on the total number of males in the PAS. According to an embodiment, the PAS consists essentially in recurring units (RPAS).

[0044] Preferably, said PAS polymer is selected from the group consisting of poly(2,4-toluene sulfide), poly(4,4'-biphenylene sulfide), poly(para-phenylene sulfide) (PPS), poly(ortho-phenylene sulfide), poly(meta-phenylene sulfide), poly(xylene sulfide), poly(ethylisopropylphenylene sulfide), poly(tetramethylphenylene sulfide), poly(butylcyclohexylphenylene sulfide), poly(hexyldodecylphenylene sulfide), poly(octadecylphenylene sulfide), poly(phenylphenylene sulfide), poly-(tolylphenylene sulfide), poly(benzylphenylene sulfide) and poly[octyl-4-(3-methylcyclopentyl) phenylene sulfide],

[0045] More preferably, said PAS is a PPS comprising recurring units represented by Formula I:

[0046] Even more preferably, the PPS comprises at least 50 mol. % of recurring units of Formula I, based on the total number of moles in the PPS polymer. For example at least about 60 mol. %, at least about 70 mol. %, at least about 80 mol. %, at least about 90 mol. %, at least about 95 mol. %, at least about 99 mol. % of the recurring units in the PPS are recurring units of Formula I.

[0047] According to an embodiment of the present invention, the PPS polymer is such that about 100 mol. % of the recurring units are recurring units of Formula I. According to this embodiment, the PPS polymer consists essentially of recurring units (RPPs) of Formula I.

[0048] The PAS polymer of the present invention can be obtained by a process known in the art. Reference can notably be made to WO 2015/095362 (Chevron Philipps), WO 2015/177857 (Solvay) and WO 2016/079243 (Solvay).

[0049] Preferably, said (b) poly(phenylene oxide) (PPO) polymer comprises recurring units complying with the following formulae (II): wherein

R and R’ , equal to or different from each other, are H, -CP or -CeHs and n is an integer at least equal to 1.

[0050] Preferably, said (c) poly(aryl ether ketone) (PAEK) polymer is a polymer comprising more than 50 mol% of recurring units (R-PAEK), wherein recurring units (R-PAEK) comprise a Ar — C(O) — Ar'roup, wherein Ar and Ar', equal to or different from each other, are aromatic groups. [0051] In some embodiments, the poly(aryl ether ketone) (PAEK) comprises at least

60 mol.%, at least 70 mol.%, at least 80 mol.%, at least 90 mol.%, at least 95 mol.%, or at least 99 mol.%, at least 99.5 mol%, or at least 99.9 mol% of recurring units (R-PAEK). As used herein, mol.% is relative to the total number of moles of recurring units in the poly(aryl ether ketone) (PAEK).

[0052] In some embodiments, the recurring units (R-PAEK) are selected from the group consisting of formulae (J-A) to (J-O), herein below:

wherein: each of R', equal to or different from each other, is selected from the group consisting of halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium; and j's an integer from 0 to 4.

[0053] In the recurring unit (R-PAEK), the respective phenylene moieties may independently have 1 ,2-, 1 ,4- or 1 ,3 -linkages to the other moieties different from R'n the recurring unit. Preferably, the phenylene moieties have 1 ,3- or 1 ,4- linkages, more preferably they have 1 ,4-linkage.

[0054] In some embodiments, j'n recurring unit (R-PAEK) is at each occurrence zero. That is to say that the phenylene moieties have no other substituents than those enabling linkage in the main chain of the polymer.

[0055] Preferred recurring units (R-PAEK) are thus selected from those of formulae (J'-A) to (J'-O) herein below:

[0056] In a preferred embodiment, the polyaryletherketone (PAEK) is a polyetheretherketone (PEEK).

[0057] In this embodiment, the polyetheretherketone (PEEK) has recurring units (R- PEEK) represented by either formula (J-A) or (J'-A), preferably recurring unit (R-PEEK) is represented by formula (J'-A).

[0058] According to an embodiment, the composition (C) comprises a plurality of distinct poly(aryl ether ketone) polymers, each poly(aryl ether ketone) polymer having a distinct recurring unit (R-PAEK).

[0059] Preferably, in said (d) poly(aryl ether sulfone) (PAES) polymer, at least 50 mol.% of the recurring units are recurring units of formula (IV):

(i) each R, equal to or different from each other, is selected from a halogen, an alkyl, an alkenyl, an alkynyl, an aryl, an ether, a thioether, a carboxylic acid, an ester, an amide, an imide, an alkali or alkaline earth metal sulfonate, an alkyl sulfonate, an alkali or alkaline earth metal phosphonate, an alkyl phosphonate, an amine, and a quaternary ammonium;

(ii) each h, equal to or different from each other, is an integer ranging from 0 to 4; and

(iii) T is selected from the group consisting of a bond, a sulfone group [-S(=O)2-], and a group -C(Rj)(Rk)-, where Rj and Rk, equal to or different from each other, are selected from a hydrogen, a halogen, an alkyl, an alkenyl, an alkynyl, an ether, a thioether, a carboxylic acid, an ester, an amide, an imide, an alkali or alkaline earth metal sulfonate, an alkyl sulfonate, an alkali or alkaline earth metal phosphonate, an alkyl phosphonate, an amine, and a quaternary ammonium.

[0060] Preferably, Rj and Rk are each a methyl group.

[0061] Preferably at least 60 mol.%, 70 mol.%, 80 mol.%, 90 mol.%, 95 mol.%, 99 mol.%, and most preferably all of recurring units in the poly(aryl ether sulfone) (PAES) are recurring units of formula (IV). As used herein, mol.% is relative to the total number of moles of recurring units in the poly(aryl ether sulfone) (PAES).

[0062] In an embodiment, the poly(aryl ether sulfone) (PAES) is a poly(biphenyl ether sulfone). A poly(biphenyl ether sulfone) polymer is a poly(aryl ether sulfone) which comprises a biphenyl moiety. The poly(biphenyl ether sulfone) is also known as polyphenyl sulfone (PPSLI) and for example results from the condensation of 4,4'-dihydroxybiphenyl (biphenol) and 4,4'-dichlorodiphenyl sulfone.

[0063] As used herein, a "poly(biphenyl ether sulfone) (PPSLI)" denotes any polymer of which more than 50 mol.% of the recurring units are recurring units (Rppsu) of formula (IV-A): [0064] Preferably at least 60 mol.%, 70 mol.%, 80 mol.%, 90 mol.%, 95 mol.%, 99 mol.%, and most preferably all of the recurring units in the poly(biphenyl ether sulfone) (PPSLI) are recurring units of formula (IV-A).

[0065] In an embodiment, the poly(aryl ether sulfone) (PAES) is a polyethersulfone (PES).

[0066] As used herein, a "poly(ethersulfone) (PES)" denotes any polymer of which at least 50 mol.% of the recurring units are recurring units of formula (IV-B):

(IV-B)

[0067] Preferably at least 60 mol.%, 70 mol.%, 80 mol.%, 90 mol.%, 95 mol.%, 99 mol.%, and most preferably all of the recurring units in the poly(ethersulfone) (PES) are recurring units of formula (IV-B).

[0068] In an embodiment, the poly(aryl ether sulfone) (PAES) is a polysulfone (PSU). As used herein, a "polysulfone (PSU)" denotes any polymer of which at least 50 mol.% of the recurring units are recurring units of formula (IV-C):

[0069] Preferably at least 60 mol.%, 70 mol.%, 80 mol.%, 90 mol.%, 95 mol.%, 99 mol.%, and most preferably all of the recurring units in the PSU are recurring units of formula (IV-C).

[0070] Composition (COMP) may contain at least one additional ingredient, such as those commonly used in lubricant compositions.

[0071] Non-limiting examples of suitable additives are the following: anti rust agents, antioxidants, thermal stabilizers, pour-point depressants, anti-wear agents, including those for high pressures, tracers, rheological modifiers, corrosion inhibitors, pigment, dyestuffs and fillers. [0072] Each of such at least one additional ingredient can be present in an amount from 0.1 to 15 wt.% based on the total weight of composition (COMP).

[0073] The component in the propulsion system of the electric or hybrid vehicle may be an electrical or electronic component or a mechanical component.

[0074] Among electrical and electronic components, mention may be made without limitation of electrical connectors, switchgears and circuit breakers. Among mechanical components mention may be made of ball bearings.

[0075] In other words, the present invention relates to a method for lubricating at least one electrical or electronic component in an electric or hybrid vehicle, preferably selected from electrical connectors, switchgears and circuit breakers, said method comprising applying composition (COMP) as defined above to at least a part of such component.

[0076] In still a further object, the present invention relates to the use of composition (COMP) as lubricant for mechanical components, suitable for use in the automotive industry, in particular for electric or hybrid vehicles (EV). Such components include - without limitations - ball bearings.

[0077] In other words, the present invention relates to a method for lubricating at least one mechanical component in an electric or hybrid vehicle, preferably selected from ball bearings, said method comprising applying composition (COMP) to at least a part of such a component.

[0078] In a second aspect, the present invention relates to a propulsion system of an electric or hybrid vehicle comprising the lubricant composition (COMP). All preferences detailed above for composition (COMP) equally apply to the propulsion system.

[0079] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

[0080] The present invention will be now described in more detail with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the disclosure. [0081] EXAMPLES

[0082] Materials

[0083] The different greases have a consistency NLGI 2.

[0084] PTFE : Algoflon^(R) L 203R PTFE having a particle size = 5 micrometers (commercially available by Solvay Specialty Polymers Italy S.p.A.)

[0085] PPS: Ryton® M1100 UFP (commercially available by Solvay Specialty

Polymers U.S.A., LLC.)

[0086] PFPE: Fomblin® Mnn as detailed in Table 1 (commercially available by Solvay Specialty Polymers Italy S.p.A.)

Table 1

[0087] Compositions tested contained (amounts are based on the total weight of the base grease):

- 70 wt.% of Fomblin^(R) PFPE Mnn

- 30 wt.% of thickener : PTFE or PPS

[0088] Compositions were prepared by mixing the Fomblin^(R) PFPE mentioned above with the thickener.

[0089] Testing:

[0090] The performance of the compositions was evaluated in a high speed bearing test rig, namely HighSpeed-Lifetime-False-Brinelling-Prufstand (HSLT). [0091] Tests were performed on greases loaded on bearings. Two angular contact ball bearings of type 7206-B-XL-MP (brass cage) were assembled on the test rig. An axial force of 3.5 kN was applied.

[0092] Different methods have been used (time run, speed increase, steps) to evaluate the grease performance.

[0093] Protocol 1 : 5 h test run

[0094] Results are reported in Table 2, wherein the compositions comprising PTFE are of comparison and the composition comprising PPS is according to the present invention. Table 2

[0095] At high rotational speed, compositions comprising an aromatic polymer thickener like PPS provided longer time to failure.

[0096] The data in Table 2 also showed that in general medium viscosity PFPEs (90 cSt at 40°C) were of advantage compared to high or low viscous PFPEs. They give the best results in grease formulation at high speed.

[0097] Protocol 2 : 80 h test run

[0098] The test was performed by applying the following speed/time profiles: 120 min at 1000 rpm. Then incremental speed increase in 500 rpm increments for a period of 120 min in each step.

[0099] Results from the 80 h test run are reported in Table 3, wherein the composition comprising PTFE is of comparison and the composition comprising PPS is according to the present invention.

Table 3

[00100] Compositions comprising PPS show excellent performance at high speed.

Claims

1 . A method for lubricating at least one component in the propulsion system of an electric or hybrid vehicle, said method comprising applying to at least a part of such a component a composition, [composition (COMP)] comprising:

(A) a (per)fluoropolyether polymer-base oil [PFPE base oil];

(B) from 0.1 % to 45.0% by weight, based on 100% by weight of said composition, of at least one aromatic polymer thickener.

2. The method according to Claim 1 , wherein the PFPE base oil is a (per)fluoropolyether polymer [PFPE polymer] comprising a linear or branched (per)fluoropolyether chain [PFPE chain] having two chain ends bonded to opposite sites of said chain, both chain ends comprising a linear or branched perfluorinated alkyl chain having from 1 to 6 carbon atoms, said polymer having a number average molecular weight from 500 to 100000, preferably from 2000 to 50000 as measured by NMR.

3. The method according to Claim 2, wherein each of the PFPE chain is a partially or fully fluorinated chain [chain (Rf)] comprising, preferably consisting of, repeating units R°, said repeating units being independently selected from the group consisting of:

(i) -CFXO-, wherein X is F or CF3;

(iv) -CF2CF2CF2CF2O-;

(v) -(CF2)W-CFZ-O- wherein w is an integer from 0 to 3 and Z is a group of general formula -O-R(f._a)-Y, wherein R<f._a) is a fluoropolyoxyalkene chain comprising a number of repeating units from 0 to 10, said recurring units being chosen among the followings : -CFXO- , -CF2CFXO-, -CF2CF2CF2O-, - CF2CF2CF2CF2O-, with each of each of X being independently F or CF3 and Y being a C1-C3 perfluoroalkyl group.

4. The method according to any one of the preceding Claims wherein the PFPE polymer has a viscosity of 30 to 2000 mm²/s at 20°C, measured according to ASTM D445.

5. The method according to any one of the preceding Claims wherein the PFPE polymer has has a viscosity of 35 to 550 mm²/s at 20°C, measured according to ASTM D445.

6. The method according to any one of the preceding Claims, wherein the aromatic polymer thickener is selected from the group comprising, preferably consisting of:

(a) poly(arylene sulfide) (PAS) polymer;

(b) poly(phenylene oxide) (PPO) polymer;

(c) poly(aryl ether ketone) (PAEK) polymer; and

(d) poly(aryl ether sulfone) (PAES) polymer.

7. The method according to any one of the preceding Claims, wherein said aromatic polymer thickener is poly(phenylene sulfide) (PPS).

8. The method according to any one of the preceding Claims, wherein aromatic polymer thickener is in the form of powder having an average particle size (dso):

- higher than 1 micrometer, as measured by laser diffraction particle size analysis as volume particle size distribution; and/or

- below 15 micrometers, as measured by laser diffraction particle size analysis as volume particle size distribution.

9. The method according to any one of Claims 1 to 8 wherein the component is an electrical or electronic component, preferably selected from electrical connectors, switchgears and circuit breakers.

10. The method according to any one of claims 1 to 8 wherein the component is a mechanical component, preferably selected from ball bearings.

11 . A propulsion system of an electric or hybrid vehicle comprising the lubricant composition (COMP) as defined in any one of claims 1 to 8.