Composition comprising amorphous silica and aromatic polymer

Abstract

The present invention relates to a composition comprising a) at least one hydrogenated oil and / or (per)fluorinated oil and b) from 2.00 to 55.00 wt% of a mixture comprising at least one amorphous silica and at least one aromatic polymer, wherein the wt% is relative to the total weight of the composition. The present invention also relates to use of a mixture of at least one amorphous silica and at least one aromatic polymer as a thickener in a grease formulation.

Description

1 / 27 SSPI 2023 / 016 COMPOSITION COMPRISING AMORPHOUS SILICA AND AROMATIC POLYMER CROSS REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This application claims priorities filed on 31 August 2023 in the USA with Nr. 63 / 535789 and on 15 September 2023 in Europe with Nr.23197608.5, the whole content of each of these applications being incorporated herein by reference for all purposes. TECHNICAL FIELD

[0002] The present invention relates to a composition comprising at least one hydrogenated oil and / or (per)fluorinated oil and from 2.00 to 55.00% by weight (wt.%) of a mixture comprising at least one amorphous silica and at least one aromatic polymer, wherein the wt.% is relative to the total weight of the composition. The present invention also relates to use of a mixture of an amorphous silica and an aromatic polymer as a thickener in a grease formulation. TECHNICAL BACKGROUND

[0003] It is known that certain hydrogen-based lubricants of natural or synthetic origin are endowed with remarkable lubricating properties and are available on the market at reasonable costs. Examples of hydrogen-based lubricant oils comprise mineral oils of hydrocarbon type, which are mostly petroleum fractions, animal and vegetal hydrogenated oils, synthetic hydrogenated oils including polyalphaolefins (PAO), synthetic esters such as dibasic acid esters, polyol esters, and polyesters, polyalkylene glycols (PAG), phosphate esters, alkylated naphthalenes, polyphenyl ethers, polybutenes, multiply- alkylated cyclopentanes (MAC), silane hydrocarbons, siloxanes, etc.

[0004] A possible alternative to hydrogen-based lubricants is represented by (per)fluoropolyether (PFPE) lubricants, i.e. lubricants comprising (per)fluorooxyalkylene chains, wherein the monomers consisting of (per)fluoroalkyl groups are joined by ether linkages. In particular, PFPE lubricants exhibit excellent thermal and chemical resistance such that they2 / 27 SSPI 2023 / 016 are useful in the applications under harsh conditions, e.g. very high temperatures, presence of oxygen, use of aggressive chemicals and radiations, etc. However, PFPE oils are more expensive than hydrogenated oils and hence they are used only when high performances are requested.

[0005] In parallel, polytetrafluoroethylene (PTFE) has been used both as a grease and a thickener thanks to its excellent lubricating properties in a wide temperature range. However, it is probable that use of PTFE is to be restricted due to environmental reasons.

[0006] In this regard, a grease that may function in a wide temperature range is continuously desired in this field. It is known from the prior art to use additives that stabilize oils and greases at high temperatures in an oxidizing environment and / or in the presence of metals, thus guaranteeing their stability during the use. There are various liquid stabilizing additives well known in this field. To improve the thermal stability at high temperatures, however, it is necessary to increase the amount of the additive. This eventually results in the separation of the liquid component (oil and additives) from the solid component (thickener) in a grease as the temperature increases, thus changing its initial grease consistency. Notably, the oil separation becomes more significant at temperatures higher than 200℃, where the liquid additives tend to evaporate more easily.

[0007] US 2583603 (The Honorary Advisory Council for Scientific and Industrial Research) discloses a lubricating grease wherein the thickening or grease structure forming material is an aqueous gel, such as inorganic aqueous gel. More in detail, the liquid phase of an inorganic gel such as silica aqua gels or a precipitated such as aluminum hydroxide is extracted continuously with acetone or some other volatile liquid which is mutually soluble in the liquid medium of the gel and in lubricating oil. This part of the process is continued until the original liquid phase, normally water, has been completely or very nearly completely displaced by the solvent. The resulting gel, containing a new liquid phase, is then dispersed in a proper amount of lubricating oil and the mutual solvent, which is preferably volatile, is then flashed off. The processing further includes the provision of a water-repellent coating for the solid phase at the dineric interface. The resulting grease may be passed through a colloidal mill to give the final desired stable structure. In general,3 / 27 SSPI 2023 / 016 the concentration of the solid phase in the final product will range between 5 and 20% by weight based on the total composition.

[0008] JP 2012-236929 (Toyota Motor Corp.) exemplifies compositions comprising at least one thickening agent selected from aromatic polymers and inorganic compounds, such as calcium carbonate and silica; a silicone oil; and a fibrous substance, such as aramid fibers. Silica particles are used in admixture with the aromatic polymer, and the amount of silica is from about 25 wt.% to about 43 wt.% based on the sum of silica particles and aromatic polymer.

[0009] Accordingly, various efforts have been made to find an alternative solution. As an example WO 2023 / 078890 (Solvay Specialty Polymers USA, LLC) discloses the use of an aromatic polymer powder characterized by a specific particle size and surface area capable of stabilizing hydrogenated oils and (per)fluorinated oils, at high temperatures, in particular higher than 200℃, in an oxidizing environment, even in the presence of metals.

[0010] In addition to the stability at high temperatures, a grease which may function as intended at low temperatures, e.g. less than 0℃, is also required depending on the particular applications. Most conventional greases can operate effectively at low temperatures ranging from 0 to -10℃, whereas at extremely lower temperatures, e.g. below -10℃, conventional greases are not recommended as their performance is limited by the pour point of the base oil.

[0011] It was surprisingly found by the inventors that a composition comprising a mixture of an amorphous silica and an aromatic polymer in combination with at least one hydrogenated oil and / or (per)fluorinated oil may deliver a particularly advantageous combination of properties, i.e. excellent low temperature performance with less thickener content and better wear prevention, while maintaining similar level of oil separation. SUMMARY OF THE INVENTION

[0012] A first object of the present invention is a composition comprising: a) at least one hydrogenated oil and / or (per)fluorinated oil; and b) from 2.00 to 55.00 wt.% of a mixture comprising:4 / 27 SSPI 2023 / 016 i) at least one amorphous silica; and ii) at least one aromatic polymer; wherein the wt.% is relative to the total weight of the composition.

[0013] A second object of the present invention is use of a mixture of i) at least one amorphous silica and ii) at least one aromatic polymer as a thickener in a grease formulation. In a preferred embodiment, i) the amorphous silica is a precipitated silica. DETAILED DESCRIPTION OF THE INVENTION

[0014] Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub- ranges encompassed within that range as if each numerical value and sub- range is explicitly recited. In the context of the present invention, the term ‘percent by weight’ (wt.%) indicates the content of a specific component in a mixture, calculated as the ratio between the weight of the component and the total weight of the mixture. As used herein, the concentration of recurring units in ‘percent by mol’ (mol%) refers to the concentration relative to the total number of recurring units in the polymer, unless explicitly stated otherwise.

[0015] It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the invention as claimed. Accordingly, various changes and modifications described herein will be apparent to those skilled in the art. Moreover, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

[0016] For the purpose of the present description and of the following claims: 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.

[0017] The present invention provides a composition comprising:5 / 27 SSPI 2023 / 016 a) at least one hydrogenated oil and / or (per)fluorinated oil; and b) from 2.00 to 55.00 wt.% of a mixture (“Mixture M” hereinafter) comprising: i) at least one amorphous silica; and ii) at least one aromatic polymer; wherein the wt.% is relative to the total weight of the composition.

[0018] The composition may comprise from 5.00 to 55.00 wt.% of Mixture M, wherein the wt.% is relative to the total weight of the composition.

[0019] Preferably, the composition comprises from 8.00 to 55.00 wt.% of Mixture M, wherein the wt.% is relative to the total weight of the composition.

[0020] Advantageously, the composition comprises from 10.00 to 55.00 wt.% of Mixture M, wherein the wt.% is relative to the total weight of the composition.

[0021] The composition may comprise: a) from 65.00 to 95.00 wt% of at least one (per)fluorinated oil; and b) from 5.00 to 35.00 wt% of Mixture M; wherein the wt% is relative to the total weight of the composition.

[0022] The composition may comprise: a) from 65.00 to 95.00 wt% of a mixture of a (per)fluorinated oil and a hydrogenated oil; and b) from 5.00 to 35.00 wt% of Mixture M; wherein the wt% is relative to the total weight of the composition.

[0023] Preferably, the composition comprises: a) from 70.00 to 90.00 wt% of at least one (per)fluorinated oil; and b) from 10.00 to 30.00 wt% of Mixture M; wherein the wt% is relative to the total weight of the composition.

[0024] Advantageously, the composition comprises: a) from 40.00 to 90.00 wt% of at least one hydrogenated oil; and b) from 10.00 to 60.00 wt% of Mixture M; wherein the wt% is relative to the total weight of the composition.

[0025] Mixture M typically comprises: - from 0.05 to 5.00 wt% of i) at least one amorphous silica; and - from 95.00 to 99.95 wt% of ii) at least one aromatic polymer,6 / 27 SSPI 2023 / 016 wherein the wt% is relative to the total weight of Mixture M.

[0026] Preferably, Mixture M comprises: - from 0.10 to 4.00 wt% of i) at least one amorphous silica; and - from 96.00 to 99.90 wt% of ii) at least one aromatic polymer, wherein the wt% is relative to the total weight of Mixture M.

[0027] Advantageously, Mixture M comprises: - from 0.15 to 2.50 wt% of i) at least one amorphous silica; and - from 98.00 to 99.50 wt% of ii) at least one aromatic polymer, wherein the wt% is relative to the total weight of Mixture M.

[0028] The amorphous silica may be selected from the group consisting of a precipitated silica and a fumed silica.

[0029] In the present invention, the term “fumed silica”, a.k.a. pyrogenic silica, is intended to denote finely divided particles of an amorphous silica (silicon dioxide, SiO2) produced by a continuous high-temperature hydrolysis of silicon tetrachloride (SiCl4) in a H2 / O2 flame on an industrial scale. Fumed silica consists of microscopic droplets of amorphous silica fused into branched three-dimensional (3-D) secondary particles that subsequently agglomerate into tertiary particles. The resulting powders have an extremely low bulk density and high surface area. Fumed silica has a very strong thickening effect. Primary particles size is from about 5 to about 50 nm and have specific surface area of from about 50 to about 600 m2 / g.

[0030] In the present invention, the term “precipitated silica” is intended to denote an amorphous silica that is prepared by precipitation from a solution containing silicate salts, for instance sodium silicate, reacting with an acidifying agent, for instance sulfuric acid. Precipitated silica particles are porous. Its primary structures typically have a diameter of from about 5 to 100 nm and specific surface area of from about 5 to about 100 m2 / g.

[0031] Notably, non-limiting examples of precipitated silica which could be used in the present invention are for instance Tixosil®43, Tixosil®68B, Tixosil®331 or Tixosil®365, all commercially available from Solvay.

[0032] Preferably, the amorphous silica is a precipitated silica.

[0033] The aromatic polymer may be selected from the group consisting of: - a poly(arylenesulfide) (PAS) polymer;7 / 27 SSPI 2023 / 016 - a poly(phenyleneoxide) (PPO) polymer; - a poly(aryletherketone) (PAEK) polymer; and - a poly(arylethersulfone) (PAES) polymer.

[0034] Preferably, the aromatic polymer is in the form of powders having an average particle size distribution (d50) measured pursuant to ISO 13320 between 1.0 and 15.0 μm.

[0035] More preferably, the aromatic polymer is in the form of powders having an average particle size distribution (d50) measured pursuant to ISO 13320 between 5.0 and 10.0 μm.

[0036] Preferably, the aromatic polymer is in the form of powders having a specific surface area measured by gas adsorption using the BET method pursuant to ISO 9277 between 0.5 and 20.0 m2 / g.

[0037] More preferably, the aromatic polymer is in the form of powders having a specific surface area measured by gas adsorption using the BET method pursuant to ISO 9277 between 1.0 and 15.0 m2 / g.

[0038] Even more preferably, the aromatic polymer is in the form of powders having an average particle size distribution (d50) measured pursuant to ISO 13320 between 1.0 and 15.0 μm and a specific surface area measured by gas adsorption using the BET method pursuant to ISO 9277 between 0.5 and 20.0 m2 / g.

[0039] In the present invention, the aromatic polymer may be either (fully or partially) fluorinated or non-fluorinated.

[0040] Preferably, the PAS polymer is a polymer comprising recurring units represented by Formula (I) -(Ar-S)-, wherein Ar is an arylene group, also called herein recurring unit (RPAs).

[0041] The arylene group (Ar) of the PAS polymer can be substituted or unsubstituted. In a particular embodiment, the arylene group (Ar) is substituted with at least one functional group. Non-limiting examples of the functional group are for instance amino group (–NH2), sulfino group (- SO2H), sulfo group (-SO3H), phosphono group (-PO3H2), phosphonooxy group (-OPO3H2), isocyanate group (-NCO), cyano group (-CN), nitroso group (-N=O), etc.8 / 27 SSPI 2023 / 016

[0042] Additionally, the PAS polymer can include any isomeric relationship of the sulfide linkages in the polymer, i.e. when the arylene group is a phenylene group, the sulfide linkages can be in ortho-, meta-, para-positions, or combinations thereof.

[0043] For instance, the PAS polymer may be a polymer comprising recurring units represented by Formula (I-A):

[0044] Preferably, the PAS polymer comprises at least 5.0, at least 10.0, at least 20.0, at least 30.0, at least 40.0, at least 50.0, at least 60.0, at least 70.0, at least 80.0, at least 90.0, at least 95.0, at least 98.0% by moles (mol%) of recurring units (RPAs), based on the total number of moles in the PAS polymer.

[0045] More preferably, the PAS polymer consists essentially of recurring units (RPAs).

[0046] Preferably, the PAS polymer is selected from the group consisting of poly(2,4-toluenesulfide), poly(4,4'-biphenylenesulfide), poly(para- phenylenesulfide) (PPS), poly(ortho-phenylenesulfide), poly(meta- phenylenesulfide), poly(xylenesulfide), poly(ethylisopropylphenylene sulfide), poly(tetramethylphenylene sulfide), poly(butylcyclohexylphenylene sulfide), poly(hexyldodecylphenylene sulfide), poly(octadecylphenylene sulfide), poly(phenylphenylene sulfide), poly(tolylphenylenesulfide), poly(benzylphenylenesulfide), and poly(octyl-4-(3-methylcyclopentyl) phenylenesulfide).

[0047] More preferably, the PAS polymer is a poly(phenylene sulfide) (PPS) polymer comprising recurring units represented by Formula (I-B):

[0048] Even more preferably, the PPS polymer comprises at least 50.0 mol% of recurring units of Formula (I), based on the total number of moles in the PPS polymer. For example, at least about 60.0 mol%, at least about 70.0 mol%,9 / 27 SSPI 2023 / 016 at least about 80.0 mol%, at least about 90.0 mol%, at least about 95.0 mol%, or at least about 99.0 mol% of the recurring units in the PPS are recurring units of Formula (I-B).

[0049] According to one embodiment, 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-B).

[0050] 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 A1 (Chevron Phillips), WO 2015 / 177857 A1 (Solvay) and WO 2016 / 079243 A1 (Solvay).

[0051] Preferably, the PPO polymer comprises recurring units complying with the following formulae (II):wherein R and R’, equal to or different from each other, are H, -CH3 or - C6H5; and n is an integer at least equal to 1.

[0052] Preferably, the PAEK polymer is a polymer comprising more than 50.0 mol% of recurring units (RPAEK), wherein recurring units (RPAEK) comprise a Ar—C(O)—Ar' group, wherein Ar and Ar', equal to or different from each other, are aromatic groups.

[0053] In some embodiments, the PAEK comprises at least 60.0 mol%, at least 70.0 mol%, at least 80.0 mol%, at least 90.0 mol%, at least 95.0 mol%, at least 99.0 mol%, at least 99.5 mol%, or at least 99.9 mol% of recurring units (RPAEK). As used herein, mol% is relative to the total number of moles of recurring units in the PAEK polymer.

[0054] In some embodiments, the recurring units (RPAEK) are selected from the group consisting of formulae (J-A) to (J-O), herein below:10 / 27 SSPI 2023 / 01611 / 27 SSPI 2023 / 016wherein 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' is an integer from 0 to 4.

[0055] In the recurring unit (RPAEK), the respective phenylene moieties may independently have 1,2-, 1,4- or 1,3-linkages to the other moieties different from R' in the recurring unit. Preferably, the phenylene moieties have 1,3- or 1,4-linkages, more preferably 1,4-linkages.

[0056] In some embodiments, j' in recurring unit (RPAEK) 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.12 / 27 SSPI 2023 / 016

[0057] Preferred recurring units (RPAEK) are thus selected from those of formulae (J'-A) to (J'-0) herein below:13 / 27 SSPI 2023 / 016.

[0058] Preferably, the PAEK polymer is a polyetheretherketone (PEEK) polymer.

[0059] The PEEK polymer may have recurring units (RPEEK) represented by either formula (J-A) or (J'-A), preferably by formula (J'-A).

[0060] The composition may comprise a plurality of distinct poly(aryletherketone) (PAEK) polymers, each PAEK polymer having a distinct recurring unit (RPAEK).

[0061] Preferably, in the poly(arylethersulfone) (PAES) polymer, at least 50.0 mol% of the recurring units are recurring units (RPAES) of formula (III):wherein: - each R, equal to or different from each other, is selected from a group consisting of 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; - each h, equal to or different from each other, is an integer ranging from 0 to 4; and14 / 27 SSPI 2023 / 016 - 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 group consisting of 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.

[0062] More preferably, Rj and Rk are methyl groups.

[0063] Preferably, at least 60.0 mol%, at least 70.0 mol%, at least 80.0 mol%, at least 90.0 mol%, at least 95.0 mol%, at least 99.0 mol%, and most preferably all of recurring units in the PAES polymer are recurring units of formula (III). As used herein, mol% is relative to the total number of moles of recurring units in the PAES polymer (RPAES).

[0064] In one embodiment, the PAES polymer is a poly(biphenylethersulfone). A poly(biphenylethersulfone) polymer is a poly(arylethersulfone) which comprises a biphenyl moiety. The poly(biphenylethersulfone) (PPSU) polymer is also known as polyphenylsulfone (PPSU) that may be obtained from the condensation of 4,4'-dihydroxybiphenyl (biphenol) and 4,4'- dichlorodiphenylsulfone.

[0065] As used herein, a PPSU polymer denotes any polymer of which more than 50.0 mol% of the recurring units are recurring units (Rppsu) of formula (III- A):(III-A).

[0066] Preferably, at least 60.0 mol%, at least 70.0 mol%, at least 80.0 mol%, at least 90.0 mol%, at least 95.0 mol%, at least 99.0 mol%, and most preferably all of the recurring units in the PPSU polymer are recurring units of formula (III-A).

[0067] In one embodiment, the PAES polymer is a polyethersulfone (PES) polymer.15 / 27 SSPI 2023 / 016

[0068] As used herein, a PES polymer denotes any polymer of which at least 50.0 mol% of the recurring units are recurring units of formula (III-B):(III-B).

[0069] Preferably, at least 60.0 mol%, at least 70.0 mol%, at least 80.0 mol%, at least 90.0 mol%, at least 95.0 mol%, at least 99.0 mol%, and most preferably all of the recurring units in the PES polymer are recurring units of formula (III-B).

[0070] In one embodiment, the PAES polymer is a polysulfone (PSU) polymer. As used herein, a PSU polymer denotes any polymer of which at least 50.0 mol% of the recurring units are recurring units of formula (III-C):

[0071] Preferably, at least 60.0 mol%, at least 70.0 mol%, at least 80.0 mol%, at least 90.0 mol%, at least 95.0 mol%, at least 99.0 mol%, and most preferably all of the recurring units in the PSU polymer are recurring units of formula (III-C).

[0072] The hydrogenated oil may be a mineral oil or a synthetic oil, such as polyalphaolefins (PAO) and polyalkylene glycol (PAG); esters; silicon oils; polyphenyl ethers; and the like.

[0073] The (per)fluorinated oil may be a (per)fluoropolyether (PFPE) polymer.

[0074] Preferably, the PFPE polymer comprises 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: - -CFXO-, wherein X is F or CF3; - -CFXCFXO-, wherein X, equal or different at each occurrence, is F or CF3, with the proviso that at least one of X is -F; - -CF2CF2CW2O-, wherein each of W, equal or different from each other, are F, Cl, H;16 / 27 SSPI 2023 / 016 - -CF2CF2CF2CF2O-; and - -(CF2)j-CFZ-O- wherein j is an integer from 0 to 3 and Z is a group of general formula -O-R(f-a)-T, wherein R(f-a)is a fluoropolyoxyalkene chain comprising a number of repeating units from 0 to 10, said recurring units being chosen among -CFXO- , -CF2CFXO-, -CF2CF2CF2O-, and - CF2CF2CF2CF2O-, with each of X being independently F or CF3and T being a C1-C3 perfluoroalkyl group.

[0075] Preferably, the chain (Rf) complies with the following formula: (Rf-I) -[(CFX1O)g1(CFX2CFX3O)g2(CF2CF2CF2O)g3(CF2CF2CF2CF2O)g4]- wherein: - X1is 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; and - g1, g2 , g3, and g4, equal or different from each other, are independently integers ≥0, such that g1+g2+g3+g4 is in the range from 2 to 300, preferably from 2 to 100; 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.

[0076] More preferably, the chain (Rf) is selected from chains of formula: (Rf-IIA) -[(CF2CF2O)a1(CF2O)a2]- wherein: a1 and a2 are independently integers ≥ 0 such that the number average molecular weight is between 400 and 10,000 as determined via NMR, preferably between 400 and 5,000; both a1 and a2 are preferably different from zero, with the ratio a1 / a2 being preferably comprised between 0.1 and 10; (Rf-IIB) -[(CF2CF2O)b1(CF2O)b2(CF(CF3)O)b3(CF2CF(CF3)O)b4]- wherein: b1, b2, b3, b4, are independently integers ≥ 0 such that the number average molecular weight is between 400 and 10,000 as determined via NMR, preferably between 400 and 5,000; preferably b1 is 0, b2, b3, b4 are > 0, with the ratio b4 / (b2+b3) being ≥1; (Rf-IIC) -[(CF2CF2O)c1(CF2O)c2(CF2(CF2)cwCF2O)C3]-17 / 27 SSPI 2023 / 016 wherein: cw = 1 or 2; and c1, c2, and c3 are independently integers ≥ 0 chosen so that the number average molecular weight is between 400 and 10,000 as determined via NMR, preferably between 400 and 5,000; preferably c1, c2 and c3 are all > 0, with the ratio c3 / (c1+c2) being generally lower than 0.2.

[0077] Still more preferably, the chain (Rf) complies with the formula below: (Rf-III) -[(CF2CF2O)a1(CF2O)a2]- wherein: a1 and a2 are integers > 0 such that the number average molecular weight is between 400 and 10,000 as determined via NMR, preferably between 400 and 5,000, with the ratio of a1 / a2 being generally comprised between 0.1 and 10, more preferably between 0.2 and 5.

[0078] The composition of the present invention can additionally comprise additives, if required by the final use, such as for example those commonly used in a grease composition. Non-limiting examples of suitable additives are the following: antirust agents, anti-corrosion agents, antioxidants, thermal stabilizers, light stabilizers, tackifiers, viscosity modifiers, static- dissipative agents, pour-point depressants, anti-wear agents, including those for high pressures, tracers, dyestuffs and fillers.

[0079] The amount of optional additive is from 0 to 10.0 wt% of the total weight of the composition. In a particular embodiment, the amount of additive(s) is from 0.1 to 10.0 wt%, preferably from 0.2 to 5.0 wt%, more preferably from 0.5 to 3.0 wt%, relative to the total weight of the composition.

[0080] The choice of additive(s) is not particularly limited provided that it is suitable for improving the performance of intended use.

[0081] Preferably, the composition of the present invention is advantageously free from PTFE and / or free from dispersants such as, surfactants, in particular non-ionic surfactants.

[0082] The composition of the present invention can be prepared according to methods known in the art, depending on the final use for which said composition is intended.

[0083] The composition of the present invention is ready to use or can be added to another oil / grease composition.18 / 27 SSPI 2023 / 016

[0084] The second object of the present invention is use of a mixture of i) at least one amorphous silica and ii) at least one aromatic polymer as a thickener in a grease formulation.

[0085] Preferably, the amorphous silica is a precipitated silica.

[0086] The mixture may comprise from 0.05 to 5.00 wt% of an amorphous silica, the wt% being relative to the total weight of the mixture.

[0087] The mixture of the present invention may be added to either a hydrogenated oil or (per)fluorinated oil to produce a grease composition.

[0088] Particularly, the mixture of the present invention may be added to a base oil comprising a hydrogenated oil and a (per)fluorinated oil to produce a grease composition.

[0089] Another object of the present invention is a method for lubricating at least one component in an industrial application, said method comprising applying to at least a part of such a component a composition comprising at least one hydrogenated oil and / or (per)fluorinated oil and a mixture comprising at least one amorphous silica and at least one aromatic polymer.

[0090] Particularly, said method is for lubricating at least one component in an automotive application, in particular for electric vehicles (EV), an electrical / electronics application, an aerospace application, or a hydraulic system.

[0091] Non-limiting examples of said component include bearings such as anti- friction bearings, plain bearings, etc.; ball bearings, in particular in electric vehicles; gears such as (spiral) bevel gears, hypoid gears, crown gears, (double) helical gears, spur gears, etc.; conveyors, such as chain conveyers, belt conveyors, spiral conveyors, flexible conveyors, etc.; compressors, electrical connectors, pumps, such as gear pumps, screw pumps, etc., turbines, and the like.

[0092] 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.

[0093] The invention will be now explained in more detail with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the invention.19 / 27 SSPI 2023 / 016

[0094] EXAMPLES

[0095] Raw Materials - PAO (hydrogenated oil): Synfluid® mPAO 40 cSt, commercially available from Chevron Phillips Chemicals; - PFPE ((per)fluorinated oil): Fomblin® M30, commercially available from Solvay Specialty Polymers Italy, S.p.A.; - Amorphous silica ^ Precipitated silica: Tixosil® 43 (T43), commercially available from Solvay S.A. (in micropowders with d50 = 7.0 μm); ^ Fumed silica: Aerosil® 130 (A130), commercially available from Evonik (in micropowders with d50 = 21.0 μm); - Aromatic polymer ^ PPS: Ryton® M1100 UFP, commercially available from Solvay Specialty Polymers USA, LLC (in micropowders with d50= 5.0 μm and specific surface area = 1.7 m2 / g); ^ PEEK: Ketaspire® KT-820 UFP, commercially available from Solvay Specialty Polymers USA, LLC (in micropowders with d50= 10.0 μm and specific surface area = from 5.0 to 15.0 m2 / g); ^ PTFE: Algoflon® L203R, commercially available from Solvay Specialty Polymers Italy, S.p.A (in micropowders with d50= 5.0 μm and specific surface area = 10.0 m2 / g).

[0096] Measurement standards:

[0097] Particle size distribution (d50) was measured by laser diffraction particle size analysis according to ISO 13320.

[0098] Specific surface area of the powder was determined by gas adsorption using the BET (Brunauer-Emmett-Teller) method according to ISO 9277.

[0099] Preparation of compositions:

[0100] One aromatic polymer and one amorphous silica were premixed at a defined weight ratio as indicated in Table 1 below so as to produce premix powders and subsequently the premix powders were further mixed with an oil, either hydrogenated or (per)fluorinated, to produce a composition.20 / 27 SSPI 2023 / 016

[0101] The concentration of the aromatic polymer in the oil was augmented until a grease consistency value became two (NLGI grade, aka NLGI consistency number), according to ASTM D217-10 (worked (grease) penetration range at 25℃ being from 265 to 295 mm in 10 minutes) to produce each composition. NLGI refers to National Lubricating Grease Institute. Table 1 Aromatic polymer Amorphous silica (wt%)* Oil (wt%)** E1 PPS T43 (0.2) PFPE (75.0) E2 PPS T43 (2.0) PFPE (75.0) E3 PPS A130 (0.2) PFPE (75.0) E4 PPS A130 (2.0) PFPE (75.0) E5 PEEK T43 (0.2) PFPE (70.0) E6 PPS T43 (0.2) PAO (45.5) CE1 PPS - PFPE (70.0) CE2 PPS - PAO (45.5) CE3 PEEK - PFPE (70.0) CE4 PTFE - PFPE (70.0) *wt% relative to the total weight of the mixture of an aromatic polymer and an amorphous silica; **wt% relative to the total weight of a composition consisting of an oil , an aromatic polymer and an amorphous silica, if any.

[0102] Characterization of compositions:

[0103] Oil separation was determined according to ASTM D6184 for 30 hours at 204°C for the compositions comprising PFPE and at 120°C for the compositions comprising PAO.

[0104] The torque at low temperature was evaluated according to ASTM D1478 in a ball bearing (Deep Groove Ball Bearing 6204 from AB SKF) at a rotation speed of 1 rpm for 1 hour, at a temperature of -40°C for the compositions comprising PFPE and at a temperature of -20°C for the compositions comprising PAO.

[0105] The wear preventive characteristics of the lubricating greases were determined according to the ASTM D2266 in the four-ball wear test. The21 / 27 SSPI 2023 / 016 wear scar diameter (WSD) on the balls were measured with a profilometer.

[0106] Results:

[0107] The results are shown in Table 2 below.

[0108] E1-E4 demonstrated that the presence of an amorphous silica has a major impact on the starting and running torques of a bearing at low temperature, in comparison to CE1.

[0109] The data of examples E1-E4 in comparison to those of CE1 show that a lower content of Mixture M is required to achieve significant improvements in terms of starting and running torque at low temperature.

[0110] The compositions comprising Mixture M containing PEEK as an aromatic polymer showed similar impact on the starting and running torques, i.e. E5 vs. CE3.

[0111] When PAO was used as an oil instead of PFPE, the decrease of the torques, notably the starting torque, was also observed, i.e. E6 vs. CE2.

[0112] The oil separation levels of the compositions were not significantly impacted by the presence of amorphous silica, but better wear preventive characteristics were observed with PPS-based and PEEK-based compositions in comparison to PTFE-based ones.

[0113] Accordingly, it was clearly demonstrated that the combined use of an aromatic polymer and an amorphous silica in a grease formulation (either in a hydrogenated oil or in a (per)fluorinated oil) according to the present invention can exhibit excellent performance in terms of the starting and running torques of a bearing at low temperatures in addition to the improved wear preventive characteristics, while maintaining the level of oil separation. Table 2 Oil separation Torque (g·cm) WSD (mm) (wt%) Starting torque Running torque E1 10.96 (204°C) 936 (-40°C) 262 (-40°C) 0.69 E2 11.07 (204°C) 926 (-40°C) 232 (-40°C) 0.76 E3 10.53 (204°C) 1558 (-40°C) 508 (-40°C) 0.93 E4 10.21 (204°C) 1433 (-40°C) 839 (-40°C) 0.7922 / 27 SSPI 2023 / 016 E5 10.78 (204°C) 1425 (-40°C) 721 (-40°C) 0.75 E6 0.29 (120°C) 1893 (-20°C) 632 (-20°C) 0.94 CE1 9.84 (204°C) 2849 (-40°C) 1547 (-40°C) 0.86 CE2 0.11 (120°C) 3574 (-20°C) 637 (-20°C) 0.70 CE3 11.28 (204°C) 2443 (-40°C) 773 (-40°C) 0.63 CE4 8.99 (204°C) 926 (-40°C) 417 (-40°C) 1.42

Claims

23 / 27 SSPI 2023 / 016 Claims Claim 1. A composition comprising: a) at least one hydrogenated oil and / or (per)fluorinated oil; and b) from 2.00 to 55.00% by weight (wt%) of a mixture comprising: i) at least one amorphous silica; and ii) at least one aromatic polymer; wherein the wt% is relative to the total weight of the composition. Claim 2. The composition according to claim 1, wherein b) the mixture comprises: - from 0.05 to 5.00 wt% of i) the amorphous silica; and - from 95.00 to 99.95 wt% of ii) the aromatic polymer, wherein the wt% is relative to the total weight of b) the mixture. Claim 3. The composition according to claim 1 or 2, wherein i) the amorphous silica is selected from the group consisting of a precipitated silica and a fumed silica, preferably a precipitated silica. Claim 4. The composition according to any one of claims 1 to 3, wherein ii) the aromatic polymer is in the form of powders having an average particle size distribution (d50) measured pursuant to ISO 13320 between 1.0 and 15.0 μm and a specific surface area measured by gas adsorption using the BET method pursuant to ISO 9277 between 0.5 and 20.0 m2 / g. Claim 5. The composition according to any one of claims 1 to 4, wherein ii) the aromatic polymer is selected from the group consisting of - a poly(arylenesulfide) (PAS) polymer; - a poly(phenyleneoxide) (PPO) polymer; - a poly(aryletherketone) (PAEK) polymer; and - a poly(arylethersulfone) (PAES) polymer.24 / 27 SSPI 2023 / 016 Claim 6. The composition according to claim 5, wherein the PAS polymer comprises recurring units represented by Formula (I) –(Ar-S)- (RPAS), Ar being an arylene group. Claim 7. The composition according to claim 5, wherein the PPO polymer comprises recurring units represented by the following formula (II):wherein R and R’, equal or different from each other, are H, -CH3 or –C6H5; and N is an integer of 1 or more. Claim 8. The composition according to claim 5, wherein the PAEK polymer comprises more than 50% by moles (mol%) of the recurring units of Ar-C(O)- Ar’ (RPAEK), wherein Ar and Ar’, equal to or different from each other, are aromatic groups. Claim 9. The composition according to claim 5, wherein the PAES polymer comprises more than 50 mol% of the recurring units represented by the following formula (III):wherein: - 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 metal or alkaline earth metal sulfonate, an alkyl sulfonate, an alkali metal or alkaline earth metal phosphonate, an alkyl phosphonate, an amine, and a quarternary ammonium;25 / 27 SSPI 2023 / 016 - each h, equal to or different from each other, is an integer ranging from 0 to 4; and - T is selected from the group consisting of a covalent bond, a sulfone group [-S(=O)2-], and a group -C(Rj)(Rk)-, Rjand Rk, equal to or different from each other, being 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 metal or alkaline earth metal sulfonate, an alkyl sulfonate, an alkali metal or alkaline earth metal phosphonate, an alkyl phosphonate, an amine, and a quaternary ammonium. Claim 10. The composition according to any one of claims 1 to 9, wherein a) the hydrogenated oil is a mineral oil or synthetic oil, preferably selected from the group consisting of polyalphaolefins (PAO), polyalkylene glycols (PAG), esters, silicon oils, and polyphenyethers. Claim 11. The composition according to any one of claims 1 to 9, wherein a) the (per)fluorinated oil is a (per)fluoropolyether (PFPE) polymer. Claim 12. The composition according to claim 11, wherein the PFPE polymer comprises a partially or fully fluorinated chain [chain (Rf)] comprising repeating units that are independently selected from the group consisting of: - -CFXO-, wherein X is F or CF3; - -CFXCFXO-, wherein X, equal or different at each occurrence, is F or CF3, with the proviso that at least one X is F; - -CF2CF2CW2O-, wherein each W, equal or different from each other, is F, Cl, or H; - -CF2CF2CF2CF2O-; and - -(CF2)j-CFZ-O- wherein j is an integer from 0 to 3 and Z is a group of general formula -O-R(f-a)-T, wherein R(f-a) is a fluoropolyoxyalkene chain comprising from 0 to 10 repeating units selected from the group consisting of -CFXO-, -CF2CFXO-, -CF2CF2CF2O- and -CF2CF2CF2CF2O-, X being independently F or CF3 and T being a C1-C3 perfluoroalkyl group.26 / 27 SSPI 2023 / 016 Claim 13. The composition according to any one of claims 1 to 12, further comprising at least one additive, preferably selected from the group consisting of antirust agents, anti-corrosion agents, antioxidants, thermal stabilizers, light stabilizers, tackifiers, viscosity modifiers, static-dissipative agents, pour-point depressants, and anti-wear agents. Claim 14. Use of a mixture of i) at least one amorphous silica and ii) at least one aromatic polymer as a thickener in a grease formulation. Claim 15. Use according to claim 14, wherein i) the amorphous silica is a precipitated silica. Claim 16. A method for lubricating at least one component in automotive, in electrical or electronic application, in aerospace application, or in hydraulic system, said method comprising applying to at least a part of such a component a composition according to any one of claims 1 to 13. Claim 17. The method of claim 16, wherein said at least one component is at least one ball bearing in an electric vehicle.

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