Use of diesters to improve antiwear properties of lubricant compositions

Abstract

The present invention provides a compound of formula (I): R a -C(O)-O-([C(R)2] n -O) s -C(O)-R b (I) relates to the use of diesters.

Description

[Technical field]

[0001] The present invention relates to the field of lubricant compositions, in particular lubricant compositions for vehicle engines, in particular automobile engines, and more particularly to the use in these lubricant compositions of novel compounds of the diester type as additives to advantageously improve their antiwear properties while reducing the content of antiwear additives contained therein. [Background technology]

[0002] Lubricant compositions, also called "lubricants," are commonly used in engines for the primary purpose of reducing the frictional forces between the various moving metallic parts in the engine. In addition, they are effective in preventing premature wear or damage to these parts, especially their surfaces.

[0003] For this reason, lubricant compositions are traditionally made with a base oil, which is generally combined with certain additives, particularly friction modifying additives, to enhance the lubricating properties of the base oil and to provide additional performance.

[0004] In particular, so-called "antiwear" additives are considered to reduce the wear of the mechanical parts of the engine and therefore to prevent deterioration of the engine's durability. Among these antiwear additives, mention may be made in particular of amine phosphates or also thiophosphate additives, such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, and more particularly zinc dialkyldithiophosphates or ZnDTP. Such compounds are preferably of formula Zn((SP(S)(OR')(OR''))2, where R' and R'', which may be the same or different, independently represent an alkyl group, preferably an alkyl group containing from 1 to 18 carbon atoms.

[0005] Alternative anti-wear additives of the amine tungstate or amine phosphate type or zinc-based complexes of specific formulas are also described in applications WO 2017 / 157892 and WO 2017 / 157979 in combination with polyalkylene glycols.

[0006] Unfortunately, it is undesirable for these ash-producing phosphorus and / or sulfur-based additives to be used in engine lubricants in order to meet specifications for "low ash levels" (LOW SAPS). These specifications, devised by the Association of European Automobile Manufacturers (ACEA), provide maximum sulfated ash (resulting from the presence of metals), sulfur, and phosphorus contents for lubricant compositions, hence the designation "Low SAPS" (low sulfated ash, phosphorus, and sulfur).

[0007] In fact, sulfur, phosphorus, and sulfated ash can damage aftertreatment systems installed in vehicles: ash is harmful to particulate filters, and phosphorus acts as a poison for catalytic systems.

[0008] Since these elements are present in the most commonly used additives, reducing the levels of ash, sulfur, and phosphorus in engine lubricants while maintaining the required high performance levels remains a challenge.

[0009] In particular, it would be desirable to be able to reduce the level of anti-wear additives in a lubricant to comply with the maximum content imposed for "Low SAPS" lubricants while maintaining, or even improving, the anti-wear properties of the lubricant essential to prevent premature engine deterioration. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] International Publication No. 2017 / 157892 [Patent Document 2] International Publication No. 2017 / 157979 [Non-patent literature]

[0011] [Non-Patent Document 1] Standard ASTM D2670 [Non-Patent Document 2] Standard ASTM D445 [Non-Patent Document 3] Standard ASTM D5296 [Non-Patent Document 4] Standardization Law CEC-L-36-A-90 [Non-Patent Document 5] Standard ASTM D4683 [Non-Patent Document 6] Standard ASTM D4741 [Non-Patent Document 7] Standard ASTM D445-97 [Non-Patent Document 8] Standard ASTM D2270-93 Summary of the Invention [Problem to be solved by the invention]

[0012] The object of the present invention is precisely to propose novel compounds as additives for improving the antiwear properties of lubricant compositions comprising one or more conventional antiwear additives, in particular for engines, more particularly for automotive engines. [Means for solving the problem]

[0013] Accordingly, the present invention provides a compound having the following formula (I): R a -C(O)-O-([C(R)2] n -O) s -C(O)-R b (I) (In the formula: R independently of one another represent a hydrogen atom or a linear or branched (C1-C5) alkyl group, in particular a methyl, ethyl or propyl group, in particular methyl; - s has a value of 1 or 2; - n has a value of 1, 2, or 3; it is understood that when s is different from 1, n can be the same or different; - R a and R b may be the same or different and independently of each other represent a linear or branched, saturated or unsaturated, hydrocarbon-containing group having a linear chain of 2 to 11 carbon atoms, preferably 3 to 8 carbon atoms; with the proviso that when s has a value of 2 and n is the same and has a value of 2, at least one of the R groups represents a linear or branched (C1-C5) alkyl group; With the proviso that when s has a value of 1 and n has a value of 3, at least one of the R groups attached to the carbon atom beta to the oxygen atom of the ester functional group represents a hydrogen atom. This relates to the use of diesters of DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] As illustrated in the examples presented below, the inventors have found that the addition of said diesters of formula (I) to lubricant compositions containing one or more conventionally used anti-wear additives, such as ZnDTP, makes it possible to obtain significantly improved anti-wear properties compared to those obtained with lubricant compositions using only one or more anti-wear additives.

[0015] The anti-wear properties of the composition can be evaluated more particularly according to standard ASTM D2670.

[0016] As a result, advantageously, by using one or more diesters of formula (I) according to the present invention, lubricant compositions having excellent and even improved antiwear properties can be produced using lower amounts of antiwear additives compared to conventional lubricant compositions not comprising diesters according to the present invention.

[0017] By using one or more diesters of formula (I), it is possible to reduce the content of conventional anti-wear additives, in particular the content of additives that produce ash, phosphorus or sulfur, while maintaining excellent performance in terms of anti-wear properties. The reduction in the content of anti-wear additives advantageously makes it possible to meet the specifications of "LOW SAPS" lubricant compositions.

[0018] Other characteristics, variants and advantages of the use of the diesters of formula (I) will become more apparent on reading the following description and examples, given for illustrative purposes and without limiting the invention.

[0019] Hereinafter, the expressions "between," "from," and "varying from" are intended to be synonymous and include limits unless otherwise indicated.

[0020] Diesters of formula (I) As mentioned above, the additives used according to the present invention have the following general formula (I): R a -C(O)-O-([C(R)2] n -O) s -C(O)-R b (I) (In the formula: R independently of one another represent a hydrogen atom or a linear or branched (C1-C5) alkyl group, in particular a methyl, ethyl or propyl group, in particular methyl; - s has a value of 1 or 2; - n has a value of 1, 2, or 3; in particular, n has a value of 2 or 3, more particularly, n has a value of 2, it being understood that when s is different from 1, n may be the same or different; - R a and R b may be the same or different and independently of each other represent a linear or branched, saturated or unsaturated, hydrocarbon-containing group having a linear chain of 2 to 11 carbon atoms, preferably 3 to 8 carbon atoms; with the proviso that when s has a value of 2 and n is the same and has a value of 2, at least one of the R groups represents a linear or branched (C1-C5) alkyl group; However, when s has a value of 1 and n has a value of 3, at least one of the R groups attached to the carbon atom beta to the oxygen atom of the ester functional group represents a hydrogen atom. It is a diester or a mixture of diesters.

[0021] According to one embodiment, R a and R b may be the same or different and each independently represent a linear or branched, saturated or unsaturated hydrocarbon-containing group containing 2 to 11 carbon atoms, preferably 3 to 8 carbon atoms.

[0022] The diesters of formula (I) used according to the invention will hereinafter be referred to more simply as diesters of the invention.

[0023] Preferably, in the context of the present invention: - "C" where t and z are integers t~z " means a carbon chain that can have t to z carbon atoms; for example, C 1~4 means a carbon chain which may have 1 to 4 carbon atoms; "Alkyl" means a saturated, straight or branched chain aliphatic group; e.g., C 1~4 -Alkyl group denotes a linear or branched carbon chain of 1 to 4 carbon atoms, more particularly methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl.

[0024] Preferably, in formula (I) above, when s is different from 1, all n's are the same.

[0025] In particular, n in the above formula (I) has a value of 2 or 3, and more particularly, n has a value of 2.

[0026] Preferably, at least one of the R groups represents a (C1-C5) alkyl group, in particular a linear or branched (C1-C4) alkyl group, more preferably methyl, ethyl or propyl, advantageously methyl.

[0027] According to a particularly preferred embodiment, the diester of formula (I) used according to the invention has more particularly the following formula (I'): R a -C(O)-O-([C(R)2] n -O)-([C(R')2] m -O) s-1 -C(O)-R b (I') (In the formula: R and R', independently of one another, represent a hydrogen atom or a linear or branched (C1-C5) alkyl group, in particular a methyl, ethyl or propyl group, in particular a methyl group; - s has a value of 1 or 2; - n has a value of 2; - m has a value of 2; - R a and R b may be the same or different and independently of each other represent a linear or branched, saturated or unsaturated, hydrocarbon-containing group having a linear chain of 2 to 11 carbon atoms, preferably 3 to 8 carbon atoms; With the proviso that when s has a value of 2, at least one of the R or R' groups represents a linear or branched (C1-C5) alkyl group. It may also be a diester of

[0028] Preferably, the diester used according to the invention is of formula (I'), in which at least one of R or R' represents a linear or branched, (C1-C5) alkyl group, in particular a (C1-C4) alkyl group, more preferably methyl, ethyl or propyl, advantageously methyl.

[0029] According to one embodiment variant, s in the above formula (I) or (I′) has a value of 2.

[0030] In particular, the diesters used according to the invention have the following formula (I'a): R a -C(O)-O-([C(R)2] n -O)-([C(R')2] m -O)-C(O)-R b (I'a) (In the formula: R and R', independently of one another, represent a hydrogen atom or a linear or branched (C1-C5) alkyl group, in particular a methyl, ethyl or propyl group, advantageously methyl; - n has a value of 2; - m has a value of 2; - R a and R b may be the same or different and independently of each other represent a linear or branched, saturated or unsaturated, hydrocarbon-containing group having a linear chain of 2 to 11 carbon atoms, preferably 3 to 8 carbon atoms; With the proviso that at least one of the R or R' groups represents a linear or branched (C1-C5) alkyl group, in particular methyl, ethyl or propyl, and preferably methyl. It may be of the following type.

[0031] Preferably, at least one of the R groups represents a linear or branched (C1-C5) alkyl group, in particular a methyl, ethyl or propyl group, advantageously methyl, and at least one of the R' groups represents a linear or branched (C1-C5) alkyl group, in particular a methyl, ethyl or propyl group, advantageously methyl.

[0032] Even more preferably, the diester used according to the invention may be of formula (I'a), in which one of the R groups represents a linear or branched (C1-C5) alkyl group, in particular a methyl, ethyl or propyl group, advantageously methyl, one of the R' groups represents a linear or branched (C1-C5) alkyl group, in particular a methyl, ethyl or propyl group, advantageously methyl, and the other R and R' groups represent a hydrogen atom.

[0033] In other words, according to one particular embodiment, the diester used according to the invention has the following formula (I″a): R a -C(O)-O-CHR 1 -CHR 2 -O-CHR 3 -CHR 4 -OC(O)-R b (I''a) (In the formula: - R 1 Groups and R 2 one of the groups represents a linear or branched (C1-C5) alkyl group and the other represents a hydrogen atom; - R 3 Groups and R 4 one of the groups represents a linear or branched (C1-C5) alkyl group and the other represents a hydrogen atom; - R a and R b may be the same or different and are as defined above) It may be of the following type.

[0034] In particular, the diesters used according to the invention are - R 1 Groups and R 2 one of the radicals represents a methyl, ethyl or propyl radical, advantageously methyl, the other represents a hydrogen atom; - R 3 Groups and R 4 It may be of formula (I''a) in which one of the groups represents a methyl, ethyl or propyl group, advantageously methyl, and the other represents a hydrogen atom.

[0035] According to another embodiment variant, s in the above formula (I) or formula (I′) has a value of 1.

[0036] In other words, the diester used according to the invention has the following formula (I'b): R a -C(O)-O-([C(R)2] n -O)-C(O)-R b (I'b) (In the formula: R independently of one another represent a hydrogen atom or a linear or branched (C1-C5) alkyl group, in particular a methyl, ethyl or propyl group, advantageously methyl; - n has a value of 2; - R may be the same or different a and R b represent, independently of each other, a linear or branched, saturated or unsaturated, hydrocarbon-containing group having a linear chain of 2 to 11 carbon atoms, preferably 3 to 8 carbon atoms. It may be of the following type.

[0037] Preferably, in formula (I'b) as above, at least one of R represents a linear or branched (C1-C5) alkyl group, in particular a methyl, ethyl or propyl group, advantageously methyl.

[0038] In particular, the diesters used according to the invention may be of formula (I'b) in which one of the R groups represents a linear or branched (C1-C5) alkyl group, in particular a methyl, ethyl or propyl group, advantageously methyl, and the others represent a hydrogen atom.

[0039] As described above, R in the above-mentioned formula (I), formula (I'), formula (I'a), formula (I''a), or formula (I'b) a and R b may be the same or different and represent a linear or branched, saturated or unsaturated, hydrocarbon-containing group having a linear chain of 2 to 11 carbon atoms, preferably 3 to 8 carbon atoms.

[0040] A "hydrocarbon-containing" group means any group having a carbon atom directly attached to the remainder of the molecule and having predominantly aliphatic hydrocarbon character.

[0041] Preferably, R in the above-mentioned formula (I), formula (I'), formula (I'a), formula (I''a), or formula (I'b) is a and R b has a straight chain of 3 to 6 carbon atoms.

[0042] According to one embodiment variant, R a and R b has a straight chain of 8 to 11 carbon atoms.

[0043] "Linear chain of t to z carbon atoms" means a saturated or unsaturated, preferably saturated, carbon chain which successively comprises t to z carbon atoms, whereby, optionally, carbon atoms present at branching levels of the carbon chain are not taken into account in the number of carbon atoms (t to z) constituting the linear chain.

[0044] According to a particular embodiment, in the above-mentioned formula (I), formula (I'), formula (I'a), formula (I''a) or formula (I'b), R a and R b may be the same or different and may be of vegetable, animal, or petroleum origin.

[0045] According to a particular embodiment, in the above-mentioned formula (I), formula (I'), formula (I'a), formula (I''a) or formula (I'b), R a and R b may be the same or different and represent saturated groups.

[0046] According to another particularly preferred embodiment, in the above-mentioned formula (I), formula (I'), formula (I'a), formula (I''a), or formula (I'b), R a and R b may be the same or different and represent a straight-chain group.

[0047] According to another particular embodiment, in the above-mentioned formula (I), formula (I'), formula (I'a), formula (I''a), or formula (I'b), R a and R b is saturated, C8~C 11 Especially C8~C 10 represents a linear hydrocarbon-containing group.

[0048] In particular, Ra and R b is the same.

[0049] Preferably, R a and R b represents an n-octyl group or an n-undecyl group, preferably an n-octyl group.

[0050] According to another particular embodiment, in the above-mentioned formula (I), formula (I'), formula (I'a), formula (I''a), or formula (I'b), R a and R b represents a branched chain hydrocarbon-containing group containing 2 to 11 carbon atoms, preferably 3 to 8 carbon atoms.

[0051] The diesters of formula (I) used according to the invention may be commercially available or may be prepared according to synthetic methods described in the literature and known to those skilled in the art. These synthetic methods more particularly involve the synthesis of diesters of formula HO-([C(R)2] n -O) s -OH diol compounds of formula R a -COOH and formula R b -COOH compound (R a and R b may be the same or different and are as described above) is used.

[0052] Of course, it is up to the skilled artisan to adjust the synthesis conditions to obtain the required diester in accordance with the present invention.

[0053] By way of example, the diesters of the above-mentioned formula (I), in particular of the above-mentioned formula (I′), can be prepared by reacting monopropylene glycol or polypropylene glycol, in particular monopropylene glycol (MPG) or dipropylene glycol (DPG), with one or more suitable carboxylic acids R a -COOH and carboxylic acid R b It can be obtained by esterification reaction between -COOH.

[0054] As an example, - s has a value of 2, one of the R radicals represents a linear or branched (C1-C5) alkyl radical, in particular a methyl, ethyl or propyl radical, advantageously methyl, and the others represent a hydrogen atom; one of the R' groups represents a linear or branched (C1-C5) alkyl group, in particular a methyl, ethyl or propyl group, advantageously methyl, and the others represent a hydrogen atom; The diester or mixture of diesters of formula (I′) defined above can be prepared by reacting dipropylene glycol (DPG) with one or more suitable carboxylic acids R a -COOH and carboxylic acid R b It can be obtained via an esterification reaction between -COOH.

[0055] - s has a value of 1, one of the R groups represents a linear or branched (C1-C5) alkyl group, in particular a methyl, ethyl or propyl group, advantageously methyl, and the others represent a hydrogen atom; The diesters of formula (I') defined above are prepared by reacting monopropylene glycol (MPG) with one or more suitable carboxylic acids R a -COOH and carboxylic acid R b It can be obtained via an esterification reaction between -COOH.

[0056] In particular, R a and R b In the case where each of x represents an n-octyl or n-undecyl group, the above diester or mixture of diesters can thus be obtained by esterification reaction between mono- or dipropylene glycol and nonanoic or dodecanoic acid.

[0057] In the context of the present invention, it is understood that a diester of formula (I) as defined above may be in the form of a mixture of diesters of formula (I) as defined above.

[0058] Use in lubricant compositions The diesters of formula (I) are used as additives in lubricant compositions, particularly in lubricant compositions for vehicle engines, more preferably automotive engines.

[0059] In general, the above diester or diesters of formula (I) may be used in the lubricant composition in a proportion of 1 to 30 wt.%, in particular 5 to 30 wt.%, in particular 5 to 25 wt.%, preferably 5 to 20 wt.%, relative to the total mass of the lubricant composition.

[0060] Anti-wear Additives As noted above, lubricant compositions contemplated according to the present invention include one or more conventional anti-wear additives.

[0061] "Anti-wear additive" refers to a compound that, when used in a lubricant composition, particularly a lubricant composition for a vehicle engine, especially an automobile engine, makes it possible to improve the anti-wear properties of the composition.

[0062] There are a wide variety of antiwear additives, such as polysulfide additives, sulfur-containing olefin additives, or thiophosphate additives, such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, more particularly zinc dialkyldithiophosphates or ZnDTP. Preferred compounds are of the formula Zn((SP(S)(OR)(OR'))2, where R and R', which may be the same or different, independently represent a linear or branched, preferably branched, alkyl group, preferably containing 1 to 18 carbon atoms. Preferably, at least one of the R and R' groups represents a preferably branched alkyl group having at least 6 carbon atoms, in particular 6 to 18 carbon atoms.

[0063] Thus, according to one particular embodiment, one or more diesters of formula (I) according to the invention are used in a lubricant composition in combination with one or more additives of the zinc dialkyldithiophosphate type, in particular of the above-mentioned formula Zn((SP(S)(OR)(OR'))2.

[0064] The lubricant compositions contemplated according to the invention may contain from 0.01 to 6 wt %, preferably from 0.05 to 4 wt %, more preferably from 0.1 to 2 wt % of the anti-wear additive relative to the total mass of the composition.

[0065] As mentioned above, the use of one or more diesters of formula (I) according to the invention advantageously makes it possible to improve the antiwear properties of a lubricant composition, which offers the possibility, according to the invention, to obtain lubricant compositions with excellent antiwear properties while reducing the content of conventionally used antiwear additives.

[0066] Thus, according to one particularly advantageous embodiment variant, the anti-wear additive or additives, in particular those that are a source of sulfur or phosphorus, are present in the lubricant composition in a content of less than or equal to 2 wt.%, in particular less than or equal to 1 wt.%.

[0067] More specifically, it is advantageously possible to reduce the content of conventional anti-wear additives, such as zinc dialkyldithiophosphates, in order to meet the "LOW SAPS" specifications required in lubricant compositions.

[0068] Lubricant compositions typically contain, in addition to one or more diesters of formula (I), as described above, one or more base oils in combination with one or more conventional anti-wear additives, and other additives conventionally considered in lubricant compositions.

[0069] For formulating such lubricant compositions, one or more diesters of formula (I) can be added to a base oil or mixture of base oils, and then other supplemental additives, including one or more anti-wear additives, are added.

[0070] Alternatively, one or more of the above esters of formula (I) may be added to existing, conventional lubricant formulations, in particular those containing one or more base oils and supplemental additives, in particular one or more anti-wear additives.

[0071] For example, a lubricant composition for an engine may be topped up with one or more diesters of formula (I) according to the invention, for example by adding one or more of said diesters directly to a container previously filled with a conventional lubricant formulation.

[0072] Base oil Thus, the lubricant compositions contemplated according to the invention may further comprise one or more base oils different from the diester of formula (I).

[0073] These base oils may be chosen from the base oils conventionally used in the lubricating oil field, for example synthetic or natural mineral oils, animal oils or vegetable oils, or mixtures thereof.

[0074] The base oil may be a mixture of several base oils, for example a mixture of two base oils, three base oils, or four base oils.

[0075] The base oils of the lubricant compositions envisaged according to the invention may in particular be oils of mineral or synthetic origin belonging to groups I to V according to the API classification (or their equivalents according to the ATIEL classification) as shown in Table A below, or mixtures thereof, provided that they are different from the diesters according to the invention.

[0076] [Table 1]

[0077] Mineral base oils include all types of base oils obtained by atmospheric and vacuum distillation of crude oil followed by subsequent refining operations such as solvent extraction, deasphalting, solvent dewaxing, hydrorefining, hydrocracking, hydroisomerization, and hydrofinishing.

[0078] The synthetic base oil may be an ester of a carboxylic acid with an alcohol, a polyalphaolefin or else a polyalkylene glycol (PAG) obtained by polymerization or copolymerization of alkylene oxides containing from 2 to 8 carbon atoms, in particular from 2 to 4 carbon atoms. The polyalphaolefins used as base oils are obtained, for example, starting from monomers containing from 4 to 32 carbon atoms, such as decene, octene or dodecene, and have a viscosity of 1.5 mm at 100° C. according to standard ASTM D445. 2 .seconds -1 From 15mm 2 .seconds -1 Its average molecular weight, according to standard ASTM D5296, is generally between 250 and 3000.

[0079] Mixtures of synthetic and mineral oils, which may be of biological origin, may also be used.

[0080] Generally, there are no limitations regarding the use of various base oils in a lubricant composition, except that they must have characteristics, particularly viscosity, viscosity index, sulfur content, or oxidation resistance, suitable for use in vehicle engines.

[0081] Preferably, the lubricant compositions contemplated according to the invention comprise at least one base oil selected from API Class II, III, and IV oils, and mixtures thereof.

[0082] In particular, the lubricant composition may comprise at least one Group III base oil.

[0083] A lubricant composition contemplated according to the invention may comprise, relative to its total mass, at least 50 wt. % of base oil, in particular at least 60 wt. % of base oil, more particularly from 60 to 99 wt. % of base oil.

[0084] Preferably, the one or more Group III oils represent at least 50 wt.%, in particular at least 60 wt.%, of the total mass of base oil of the composition.

[0085] Other Additives The lubricant compositions contemplated according to the invention may further comprise any type of additive suitable for use in lubricants for vehicle engines, particularly automobile engines.

[0086] These additives can be incorporated individually and / or in the form of mixtures, for example, in commercially available formulations of lubricants for vehicle engines already on the market, having performance levels defined by ACEA (Association of the European Automobile Manufacturers) and / or API (American Petroleum Institute), well known to those skilled in the art.

[0087] These additives may be selected from friction modifying additives, extreme pressure additives, detergents, antioxidants, viscosity index (VI) improvers, pour point depressants (PPDs), dispersants, antifoam agents, thickeners, and mixtures thereof, among others.

[0088] Lubricant compositions contemplated according to the present invention may include at least one friction modifying additive.

[0089] Friction modifying additives may be selected from compounds that provide metallic elements and ashless compounds.

[0090] Among the compounds that provide metal elements, there may be mentioned complexes of transition metals such as Mo, Sb, Sn, Fe, Cu, Zn, etc., whose ligands may be hydrocarbon-containing compounds containing oxygen, nitrogen, sulfur, or phosphorus atoms.

[0091] Ashless friction modifying additives are generally of organic origin and may be selected from monoesters and polyols of fatty acids, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, borated fatty epoxides, fatty amines, or glycerol esters of fatty acids. According to the present invention, the fatty compounds contain at least one hydrocarbon-containing group containing from 10 to 24 carbon atoms.

[0092] According to one advantageous embodiment, the lubricant composition comprises at least one friction modifying additive, in particular one based on molybdenum.

[0093] In particular, the molybdenum-based compound may be selected from molybdenum dithiocarbamate (Mo-DTC), molybdenum dithiophosphate (Mo-DTP), and mixtures thereof.

[0094] According to one particular embodiment, the lubricant composition comprises at least one Mo-DTC compound and at least one Mo-DTP compound. The lubricant composition may in particular comprise a molybdenum content of between 1000 ppm and 2500 ppm.

[0095] Advantageously, such compositions allow for greater fuel savings to be achieved.

[0096] Advantageously, the lubricant compositions envisaged according to the invention may comprise from 0.01 to 5 wt. %, preferably from 0.01 to 5 wt. %, more particularly from 0.1 to 2 wt. %, even more particularly from 0.1 to 1.5 wt. %, relative to the total mass of the lubricant composition, of friction modifying additives, advantageously comprising at least one molybdenum-based friction modifying additive.

[0097] The lubricant composition envisaged according to the invention may comprise at least one antioxidant.Antioxidants essentially aim to retard the deterioration of the lubricant composition during use.This deterioration may be reflected in the formation of deposits, in particular by the presence of sludge or by an increase in the viscosity of the lubricant composition.Antioxidants act in particular as radical inhibitors or hydroperoxide destroyers.

[0098] Commonly used antioxidants include phenol-type antioxidants, amine-type antioxidants, and thiophosphate antioxidants. Some of these antioxidants, such as thiophosphate antioxidants, may be sources of ash. The phenol-based antioxidants may be ashless or in the form of neutral or basic metal salts. The antioxidants are particularly selected from sterically hindered phenols, sterically hindered phenol esters, and sterically hindered phenols containing thioether bridges, diphenylamines, and esters of at least one C1-C 12 They may be selected from alkyl substituted diphenylamines, N,N'-dialkaryldiamines, and mixtures thereof.

[0099] Preferably, the sterically hindered phenol has at least one C1-C aryl group adjacent to the carbon bearing the alcohol functional group. 10 It is selected from compounds containing a phenol group substituted with an alkyl group, preferably a C1-C6 alkyl group, preferably a C4 alkyl group, preferably a tert-butyl group.

[0100] Amine compounds are another class of antioxidants that can be optionally used in combination with the phenolic antioxidants. Examples of amine compounds are aromatic amines, such as those of the formula NR 5 R 6 R 7 wherein R 5 represents an optionally substituted aliphatic or aromatic group; R 6 represents an optionally substituted aromatic group; R 7 is a hydrogen atom, an alkyl group, an aryl group, or a group of the formula R 8 S(O) z R 9 (wherein R 8 represents an alkylene group or an alkenylene group; R 9 represents an alkyl group, an alkenyl group, or an aryl group, and z represents 0, 1, or 2).

[0101] Sulfurized alkylphenols or alkali metal and alkaline earth salts can also be used as antioxidants.

[0102] The lubricant compositions envisaged according to the invention may contain all types of antioxidants known to those skilled in the art. Advantageously, the lubricant compositions contain at least one ashless antioxidant.

[0103] Advantageously, the lubricant compositions envisaged according to the invention may also contain from 0.1 to 2 wt. % relative to the total mass of the composition of at least one antioxidant.

[0104] The lubricant compositions envisaged according to the invention may comprise at least one detergent. So-called detergents generally make it possible to reduce the formation of deposits on the surfaces of metal parts by dissolving oxidation and combustion by-products.

[0105] Detergents are generally known to those skilled in the art. Detergents may be anionic compounds containing a long lipophilic hydrocarbon-containing chain and a hydrophilic head. The associated cation may be a metal cation of an alkali metal or an alkaline earth metal.

[0106] The detergents are preferably selected from alkali metal or alkaline earth metal salts of carboxylic acids, sulfonates, salicylates, naphthenates, and phenolates. The alkali and alkaline earth metals are preferably calcium, magnesium, sodium, or barium. These metal salts generally contain a stoichiometric or excess, i.e., more than the stoichiometric amount, of metal. They are overbased detergents, the excess metal that gives the detergent its overbased character is generally in the form of a metal salt insoluble in the base oil, such as carbonates, hydroxides, oxalates, acetates, glutamates, preferably carbonates.

[0107] The detergents are generally used in a content ranging from 0.5 to 8 wt%, preferably from 0.5 to 4 wt%, relative to the total mass of the lubricant composition. Advantageously, the detergents are present in a content of less than 4 wt%, in particular less than 2 wt%, in particular less than 1 wt%, or the lubricant composition does not contain detergents.

[0108] The lubricant compositions contemplated according to the invention may contain at least one pour point depressant (PPD). By slowing the formation of wax crystals, pour point depressants generally improve the low temperature behavior of the lubricant composition.

[0109] Examples of pour point depressing agents include polyalkylmethacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, and alkylated polystyrenes.

[0110] The lubricant compositions envisaged according to the invention may also contain at least one dispersant. The dispersant ensures that insoluble solid contaminants, consisting of oxidation by-products, formed when the lubricant composition is in use are kept in suspension and removed. The dispersant may be selected from Mannich bases, succinimides and derivatives thereof.

[0111] In particular, the lubricant compositions contemplated according to the invention may contain from 0.2 to 10 wt % of a dispersant, relative to the total weight of the composition.

[0112] The lubricant compositions envisaged according to the invention may also contain at least one viscosity index (VI) improver. Viscosity index (VI) improvers, in particular polymeric viscosity index improvers, make it possible to ensure good low-temperature durability and minimum viscosity at high temperatures. Examples of polymeric viscosity index improvers include polymer esters, hydrogenated or non-hydrogenated homopolymers or copolymers of styrene, butadiene and isoprene, homopolymers or copolymers of olefins such as ethylene or propylene, polyacrylates and polymethacrylates (PMA).

[0113] In particular, lubricant compositions contemplated according to the present invention may contain from 1 to 15 wt % of a viscosity index improver, based on the total weight of the lubricant composition.

[0114] The lubricant compositions contemplated according to the invention may also comprise at least an antifoam additive. The antifoam additive may be selected from polar polymers, such as polymethylsiloxanes or polyacrylates.

[0115] In particular, the lubricant compositions contemplated according to the present invention may contain from 0.01 to 3 wt % of the antifoam additive, based on the total weight of the lubricant composition.

[0116] As mentioned above, the use of one or more diesters of formula (I) as additives as claimed in accordance with the present invention makes it possible to significantly improve the anti-wear properties of lubricant compositions containing one or more conventional anti-wear additives.

[0117] As illustrated in the examples given below, the wear resistance properties can be evaluated using a tribometer according to a procedure based on standard ASTM D2670.

[0118] The lubricant compositions envisaged according to the invention may more particularly be compositions of a grade according to the SAEJ300 classification, as defined by the formula (X)W(Y), where X represents 0 or 5, and Y represents an integer between 4 and 30. This grade specifies the selection of lubricant compositions specifically for automotive engine applications, and in particular those satisfying special properties, quantified in terms of various parameters such as starting low temperature viscosity, low temperature pumpability, kinematic viscosity at low shear rate, and kinematic viscosity at high shear rate.

[0119] The viscosity grades of the lubricant compositions envisaged according to the invention are in particular - Grade according to SAEJ300 classification, as determined by formula (II) or formula (III) 0W(Y) 5W(Y) (II) (III) (wherein Y represents an integer of 4 to 20, particularly 4 to 16 or 4 to 12); or - Grade according to SAEJ300 classification, as determined by formula (IV) or formula (V) (X)W8 (X)W12 (IV) (V) (wherein X represents 0 or 5). You can choose from.

[0120] According to one particular embodiment, the grade according to the SAEJ300 classification of the lubricant composition envisaged according to the invention is selected from 0W4, 0W8, 0W12, 0W16, 0W20, 5W4, 5W8, 5W12, 5W16 and 5W20, preferably from 0W4, 0W8, 0W12, 0W16, 0W20 and 5W20.

[0121] In particular, the lubricant compositions contemplated according to the invention may have a rating according to the SAE J300 classification of 0W20 or 0W16.

[0122] Advantageously, the lubricant compositions envisaged according to the invention have a kinematic viscosity, measured at 100° C. according to standard ASTM D445, of 3 mm 2 .seconds -1 From 15mm 2 .seconds -1 Especially, 3mm 2 .seconds -1 From 13 mm 2 .seconds -1 Until then.

[0123] Advantageously, the viscosity measured at high temperature and high shear (HTHS viscosity), measured at 150°C, is greater than or equal to 1.7 mPa.s, preferably between 1.7 and 3.7 mPa.s, advantageously between 2.3 and 3.7 mPa.s.

[0124] HTHS measurements were performed at high shear (10 6 seconds -1) and at 150°C.

[0125] The invention will now be described with the aid of the following examples, given for the purpose of illustration and without limiting the invention. EXAMPLES

[0126] Example 1 Preparation of Lubricant Compositions Containing the Diesters Required According to the Invention and Comparative Compositions Lubricant compositions according to the invention using a diester of formula (I) (I1 and I2), as well as comparative compositions not containing a diester of formula (I) (C1 and C2), were formulated with the ingredients and amounts (expressed in mass percent) shown in Table 1 below.

[0127] The lubricant composition is obtained by simply mixing the following ingredients at room temperature: For example, a group III base oil (KV100=4.2 mm) available from SK Lubricants under the trade name Yubase®4. 2 / sec, KV40=19.1mm 2 / sec, VI126) antiwear additives (for example those sold under the name OLOA® 269R, Bis[O,O-bis(2-ethylhexyl)] Sodium bis(dithiophosphate) lead ), antioxidants, friction modifiers, dispersants, and detergents, as well as a conventional additive package1 - Conventional additive package 2, including anti-wear additives (bis[O-(1,3-dimethylbutyl)]bis[O-(isopropyl)]bis(zinc dithiophosphate), antioxidants, friction modifiers, dispersants, and detergents - polymethacrylate comb polymers available under the trade name Viscoplex® V3-200 from the company Evonik, and optionally - a diester of formula (I) according to the invention, obtained by esterification reaction of dipropylene glycol with at least two nonanoic fatty acids;

[0128] [Table 2]

[0129] The characteristics of the compositions thus prepared are presented in Table 2 below.

[0130] [Table 3]

[0131] Example 2 Wear resistance evaluation Evaluation method The evaluation is based on a procedure according to standard ASTM D2670, which requires the use of a FALEX tribometer under the following test conditions: - Test sample: FALEX steel - Polishing time: 300 seconds - Test duration: 180 minutes - Grinding load: 445N - Test load: 1335N - Speed: 290 rev / min - room temperature

[0132] The test results are presented below in Table 3, more specifically expressed in μm: the lower the value obtained, the better the anti-wear properties of the composition evaluated.

[0133] [Table 4]

[0134] The results show that the addition of the diesters of formula (I) according to the invention to a lubricant composition makes it possible to significantly improve its antiwear properties.

Claims

1. As an additive for improving the anti-wear properties of a lubricant composition comprising one or more anti-wear additives, R a -C(O)-O-([C(R) 2 ] n -O) s -C(O)-R b (I) (In the formula: R are each independently a hydrogen atom or a linear or branched (C 1 ~C 5 ) represents an alkyl group; - s has a value of 1 or 2; - n has a value of 1, 2, or 3; it is understood that when s is different from 1, n can be the same or different; - R a and R b may be the same or different and independently of each other represent a linear or branched, saturated or unsaturated, hydrocarbon-containing group having a linear chain of 8 to 11 carbon atoms; With the proviso that when s has a value of 2 and n is the same and has a value of 2, at least one of the R groups is a linear or branched (C 1 ~C 5 ) represents an alkyl group; With the proviso that when s has a value of 1 and n has a value of 3, at least one of the R groups attached to the carbon atom beta to the oxygen atom of the ester functional group represents a hydrogen atom. Use of a diester of the one or more diesters of formula (I) are used in a content ranging from 1 to 30 wt. %, relative to the total mass of the lubricant composition; the antiwear additive is selected from zinc dialkyldithiophosphates; the one or more anti-wear additives are present in an amount ranging from 0.01 to 2 wt. %, relative to the total mass of the lubricant composition; The lubricant composition further comprises at least 50 wt.-%, based on the total mass of the lubricant composition, of one or more base oils different from the diester of formula (I).

2. The diester of formula (I) has the formula (I'): R a -C(O)-O-([C(R) 2 ] n -O)-([C(R') 2 ] m -O) s-1 -C(O)-R b (I') (In the formula: R and R' are each independently a hydrogen atom or a linear or branched (C 1 ~C 5 ) represents an alkyl group; - s has a value of 1 or 2; - n has a value of 2; - m has a value of 2; - R a and R b may be the same or different and independently of each other represent a linear or branched, saturated or unsaturated, hydrocarbon-containing group having a linear chain of 8 to 11 carbon atoms; However, when s has a value of 2, at least one of the R or R′ groups is a linear or branched (C 1 ~C 5 ) represents an alkyl group, 2. The use according to claim 1.

3. The diester is - s has a value of 2, - one of the R groups is a linear or branched (C 1 ~C 5 ) represents an alkyl group, and the others represent hydrogen atoms; - one of the R' groups is a linear or branched (C 1 ~C 5 ) represents an alkyl group and the others represent hydrogen atoms.

4. The diester is - s has a value of 1, - one of the R groups is a linear or branched (C 1 ~C 5 ) represents an alkyl group and the others represent hydrogen atoms.

5. 5. The use according to any one of claims 1 to 4, wherein the lubricant composition is a lubricant composition for engines.

6. 6. The use according to any one of claims 1 to 5, wherein the lubricant composition comprises at least one base oil selected from API Group II, Group III, and Group IV oils.

7. 7. The use according to any one of claims 1 to 6, wherein the lubricant composition is graded according to the SAE J300 classification as defined by the formula (X)W(Y), where X represents 0 or 5 and Y represents an integer from 4 to 30.

8. 8. The use according to any one of claims 1 to 7, wherein the lubricant composition further comprises one or more additives selected from friction modifying additives, extreme pressure additives, detergents, antioxidants, viscosity index improvers, pour point depressants, dispersants, antifoam agents, thickeners, and mixtures thereof.

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