BRPI0622179A2 - grease composition for use on constant speed joints - Google Patents

Abstract

COMPOSITION OF Grease FOR USE IN CONSTANT SPEED JOINTS. To solve the problem to provide a new grease composition that provides low wear and low friction mainly to constant speed joints, a grease composition is suggested which comprises a) a base oil composition and b) 0.25% by weight up to 5 % by weight of at least one trinuclear molybdenum compound of the formula Mo ~ 3 ~ S ~ k ~ L ~ n ~ Q ~ Z1 ~ where L are independently selected labels that have the organo groups with a sufficient number of carbon atoms to make the compound soluble or dispersible in oil, n is from 1 to 4, k ranges from 4 to 7, Q is selected from the group of neutral electron donor compounds such as amines, alcohols, phosphines and ethers and z is in the range of 0 to 5 and includes non-stoichiometric values.

Description

"Grease Composition for Use in Constant Speed Joints"

The present invention relates to a lubricating grease which is intended to be used primarily in constant speed joints, especially ball joints or triped joints, which are used in motor vehicle drive units.

Component movements within constant velocity (CVJ) joints are complex with a combination of rolling, sliding and rotating. When joints are under torque, components are loaded together which can not only cause wear on component contact surfaces, but also bearing contact fatigue and significant frictional forces between surfaces. joints and frictional forces can cause noise, vibration and roughness (NVH) in the drive unit. NVH is usually "measured" by determining the axial forces generated in the piston action type CVJ. Theoretically, greases used in constant speed joints need not only reduce wear, but also have a low coefficient of friction to reduce frictional forces and to reduce or prevent NVH.

Constant speed joints also have elastomeric sealing shoes that are usually bellows shaped, one end being connected to the outside of the CVJ and the other end to the CVJ interconnect or output shaft. The shoe keeps the grease on the joint and prevents dirt and water.

Grease should not only reduce wear and friction and prevent premature onset of rolling contact fatigue in a CVJ, it should also be compatible with the elastomeric material from which the shoe is made. Otherwise there is a degradation of the shoe material which causes premature shoe breakage, which allows grease leakage and definitely the CVJ breakage. The two main types of material used for CVJ shoes are polychloroprene rubber (CR) and thermoplastic elastomer (TPE), especially ether-ester block copolymer thermoplastic elastomer (TPC-ET).

Typical CVJ greases have base oils that are mixtures of naphthenic (saturated ring) and paraffinic (straight and branched saturated chain) mineral oils. Synthetic oils may also be added. Base oils are known to have a major influence on the deterioration (swelling or shrinkage) of both CR and TPC-ET shoes. The usual mineral and synthetic base oils extract plasticizers and other oil-soluble protective agents from the shoe materials. Paraffinic mineral oils and synthetic base oils of poly-a-olefin (PAO) diffuse very little especially in shoes made of rubber material causing shrinkage, but on the other hand naphthenic mineral oils and synthetic esters diffuse into synthetic materials. Shoe and act as plasticizers can cause swelling. Replacing plasticizer or plasticizer compositions with naphthenic mineral oil can significantly reduce shoe performance, especially at low temperatures, and can cause the shoe to fail due to cold cracking, resulting in CVJ failure. If significant swelling or softening occurs, the maximum capacity of the high speed shoe is reduced due to poor speed stability and / or excessive radial expansion.

To address the above problems, US 6,656,890 Bl suggests a special combination of base oil comprising 10 to 35 wt% of one or more polyolefins, 3 to 15 wt% of one or more organic esters. 20 to 30% by weight of one or more naphthenic oils, the remainder of the combination being one or more paraffinic oils and, in addition, a thickening lithium soap and a sulfur-free friction modifier, which may be a complex of organo-molybdenum and molybdenum dithiophosphate and a zinc dialkyl dithiophosphate and other additives such as corrosion inhibitors, antioxidants, extreme pressure additives and tackifiers. However, the coefficient of friction and wear of grease compositions according to US 6,656,890 Bl as measured in SRV (abbreviation for the German Schwingungen (Vibration), Reibung (Friction), Verschleip (Wear) tests must be improved.

Thus, the object of the present invention is to provide a grease composition, primarily for use in constant speed joints, that has good compatibility with shoes made of rubber or thermoplastic elastomer and that also provides low wear and low friction in use in CVJ.

Said object of the present invention is solved by a grease composition for use in constant speed joints comprising

a) a base oil composition and

b) 0.25 wt.% to 5 wt.%, preferably 0.3 wt.% to 3 wt.%, relative to the total amount of the grease composition of at least one trinuclear molybdenum compound of formula

Mo3SkLnQz,

where L are independently selected subtitles having organo groups having a sufficient number of carbon atoms to make the compound soluble or dispersible in the oil, η is from 1 to 4, k ranges from 4 to 7, Q is selected from the group of Neutral electron donating compounds such as amines, alcohols, phosphines and ethers are in the range 0 to 5 and include non-stoichiometric values.

The number of carbon atoms present in the trinuclear molybdenum compound among all ligands, the organo groups, is at least 21 carbon atoms, preferably at least 25, more preferably at least 30 and most preferably at least 35. Trinuclear molybdenum compounds which may be used in the present invention are disclosed in US 6,172,013 B1, the disclosure of which is incorporated herein by reference. The inventors of the present invention have found that the presence of at least 0.25% by weight of the trinuclear molybdenum compound according to claim 1 would significantly decrease the coefficient of friction as well as CVJ wear in use. Surprisingly, the presence of 0.2 wt% or less of the trinuclear molybdenum compound would not lead to a much lower friction coefficient nor less wear than used in CVJs.

The number of carbon atoms present in the trinuclear molybdenum compound among all ligands, the organo groups, is at least 21 carbon atoms, preferably at least 25, more preferably at least 30 and most preferably at least 35. The trinuclear molybdenum compounds which may be used in the present invention are disclosed in US 6,172,013 B1, the disclosure of which is incorporated herein by reference. The inventors of the present invention have found that the presence of at least one trinuclear molybdenum compound and another molybdenum-containing compound according to claim 1 would significantly decrease the coefficient of friction as well as wear when used in CVJ.

As a base oil composition according to the present invention, the base oil composition as disclosed in US 6,656,890 B1, the disclosure of which is incorporated herein by reference, may preferably be used. However, any other kind of base oil composition may be used, especially a blend of mineral oils, a blend of synthetic oils or a blend of mineral and synthetic oils. The base oil composition should preferably have a kinematic viscosity between about 32 and about 250 mm / s at 40 ° C and between about 5 and about 25mm2 / s at 100 ° C. Preferably the mineral oils are selected from the group comprising at least one naphthenic oil and / or at least one paraffinic oil. Synthetic oils which may be used in the present invention are selected from a group comprising at least one poly-α-olefin (PAO) and / or at least one synthetic organic ester. The synthetic organic ester is preferably a dicarboxylic acid derivative having subgroups based on aliphatic alcohols. Preferably, aliphatic alcohols have straight or branched primary carbon chains of 2 to 20 carbon atoms. Preferably, the synthetic organic ester is selected from a group comprising sebacic acid bis (2-ethylhexylester) ("dioctyl sebacate" (DOS)), adipic acid bis (2-ethylhexylester) ("dioctyl adipate) "(DOA)) and / or the azelaic acid bis (2-ethylhexylester) (" dioctyl azelate "(DOZ)).

As a base oil composition according to the present invention, the base oil composition as disclosed in US 6,656,890 B1, the disclosure of which is incorporated herein by reference, may preferably be used. However, any other kind of base oil composition may be used, especially a blend of mineral oils, a blend of synthetic oils or a blend of mineral and synthetic oils. The base oil composition should preferably have a kinematic viscosity between about 32 and about 250 mm / s at 40 ° C and between about 5 and about 25mm / s at 100 ° C. Preferably the mineral oils are selected from the group comprising at least one poly-α-olefin (PAO) and / or at least one synthetic organic ester. The synthetic organic ester is preferably a dicarboxylic acid derivative having subgroups based on aliphatic alcohols. Preferably, the aliphatic alcohols have straight or branched primary carbon chains of 2 to 20 carbon atoms. Preferably, the synthetic organic ester is selected from a group comprising sebacic acid bis (2-ethylhexylester) ("dioctyl sebacate" (DOS)), adipic acid bis (2-ethylhexylester) ("dioctyl adipate) "(DOA)) and / or the azelaic acid bis (2-ethylhexylester) (" dioctyl azelate "(DOZ)).

If poly-α-olefin is present in the base oil composition, preferably poly-α-olefins having a viscosity in the range of from about 2 to about 40 centistokes at 100 ° C are selected. Naphthenic oils selected for the base oil composition preferably have a viscosity in the range of from 20 to 180 mm / s at 40 ° C, whereas if paraffinic oils are present in the base oil composition, preferably paraffinic oils have a viscosity in the range of from about 25 to about 400 mm / s at 40 ° C.

In another embodiment of the present invention, the grease composition also comprises at least one zinc compound additive, more preferably a zinc compound additive in an amount from approximately 0.1 wt% to approximately 1.5 wt%. . The most preferred zinc compound additive is selected from the group comprising at least one of zinc dithiophosphates (ZnDTP) and / or zinc dithiocarbamates (ZnDTC) γ ZnO and / or ZnS. Zinc dithiophosphate is preferably selected from the group of zinc dialkyl dithiophosphate of the following formula:

(R10) (R20) SP-S-Zn-S-PS (0R3X0R4)

wherein each of R 1 to R 4 inclusive may be the same or different and each represents a primary or secondary alkyl group having 1 to 24, preferably 3 to 20, more preferably 3 to 5 carbon atoms. In particular, excellent effects can be expected if the substituents R1, R2, R3 and R4 represent a combination of primary and secondary alkyl groups each having 3 to 8 carbon atoms. Zinc dithiocarbamate may preferably be selected from the zinc dialkyl dithiocarbamate of the following general formula:

<formula> formula see original document page 8 </formula>

wherein R5, R6, R7 and R8 may be the same or different and each represents an alkyl group having 1 to 24 carbon atoms or an aryl group having 6 to 30 carbon atoms.

By the addition of at least one zinc compound additive to the grease composition according to the invention, the coefficient of friction as well as CVJ wear are also significantly reduced.

According to another embodiment of the invention, the grease composition also comprises a thickener selected from the group comprising lithium soaps, calcium soaps, lithium complex soaps, calcium complex soaps and / or urea derived type thickener. . The urea derived thickener is not restricted to specifics and may be, for example, also a diurea compound and / or a polyurea compound.

For purposes of the present invention, a lithium soap or a calcium soap is a product of the reaction of at least one fatty acid with lithium hydroxide or calcium hydroxide. Preferably, the thickener may be a simple lithium or calcium soap formed with stearic acid, 12-hydroxy stearic acid, hydrogenated castor oil or other similar fatty acids or mixtures thereof or methyl esters of such acids. Alternatively, a lithium and / or calcium complex soap formed may be used, for example, starting from a long chain fatty acid mixture together with a complex forming agent, for example a borate of one or more acids. dicarboxylic acids or a mixture of short and / or medium chain carboxylic acids. The use of lithium and / or calcium complex soaps allows the grease composition according to the present invention to operate to a temperature of approximately 180 ° C, whereas with simple lithium and / or calcium soaps to Grease composition will only operate up to a temperature of approximately 120 ° C. However, mixtures of all thickeners mentioned above may also be used.

According to another embodiment of the present invention, the grease composition also comprises an additive package selected from the group of agents comprising antioxidant agents, corrosion inhibitors, anti-wear agents, friction modifiers and / or extreme pressure agents ( EP agents).

The EP agent is preferably a metal free sulfurized fatty acid methyl ester agent with a viscosity of about 25 mm / s at 40 ° C which is preferably present in an amount of from about 0.1 to about 3% by weight. , in relation to the total amount of the grease composition. The total sulfur amount of the EP agent preferably ranges from about 8 to about 10 wt% and the amount of active sulfur is about 1 wt%. Such EP agents exhibit excellent effects in preventing CVJ binding. If the sulfur content exceeds the upper limit defined above, it may promote the onset of bearing contact fatigue and wear of the contact metal components.

As an antioxidant agent, the grease composition of the present invention may comprise an amine, preferably an aromatic amine, more preferably phenyl-α-naphthylamine or diphenylamine or derivatives thereof.

The antioxidant agent is used to prevent deterioration of grease composition associated with oxidation. The grease composition according to the present invention may be in the range of from about 0.1 to about 2% by weight, based on the total amount of the grease composition, of an antioxidant agent to inhibit oxidation degradation of the base oil. , as well as increasing the life of the grease composition, thereby extending the life of the CVJ.

Typically, the last operation prior to mounting the CVJ is a scrubbing to remove machining debris and therefore the grease must absorb any traces of remaining water and prevent water from causing corrosion and adversely affecting CVJ performance; It is necessary to add a corrosion inhibitor. As a corrosion inhibitor, the grease composition according to the present invention may comprise at least one metal salt selected from the group consisting of oxidized wax metal salts, petroleum sulfonate metal salts, especially prepared by sulfonation of aromatic hydrocarbon components present in lubricating oil fractions and / or metal salts of aromatic alkyl sulfonates, such as dinonylnaphthalene sulfonic acids, alkylbenzene sulfonic acids or alkylbenzene sulfonic acids. Examples of metal salts include sodium salts, potassium salts, calcium salts, magnesium salts, zinc salts and quaternary ammonium salts, calcium salts being most preferred. Calcium salts from oxidized waxes also guarantee an excellent effect.

Anti-wear agents according to the present invention prevent metal-to-metal contact by adding film-forming compounds to protect the surface by physical absorption or chemical reaction. ZnDTP compounds can also be used as antiwear agents. As anti-corrosion agents according to the present invention preferably calcium sulfonate salts are used, preferably in an amount of from about 0.5 to about 3% by weight, relative to the total amount of the grease composition.

Traditional friction modifiers such as fatty acid amides and amine grease phosphates have been used in greases and other lubricants for many years (see, for example, Klamann, Dieter - "Lubricants", Verlag Chemie GmbH 1983, 1st edition, chapter 9.6). Its role is to make the lubricant stable but not necessarily low friction over a wide range of operating conditions.

In another preferred embodiment of the present invention, the grease composition comprises approximately 55 wt% to approximately 97.5 wt% of the base oil composition, especially

with a kinematic viscosity between about 32 and about 250 mm / s at 40 ° C and between about 5 and about 25 mm / s at 100 ° C, about 0.3 wt% to about 3 wt% of at least one molybdenum compound approximately 0.1 wt% to approximately 1.5 wt% of at least one zinc compound additive and approximately 2 wt% to approximately 25 wt% of at least one thickener, in each case with respect to total amount of grease composition. Preferably, a urea thickener may be present in a range of from about 5 to about 20% by weight, a lithium soap from 2 to 15% by weight and a calcium complex soap from about 8 to about 25%. by weight

In addition, the grease composition according to the present invention has a slip friction coefficient of no more than 0.1 as measured with an SRV test.

Best Mode for Carrying Out the Invention

To determine the effect of decreasing the coefficient of friction as well as the wear of the grease composition according to the invention, SRV tests are performed using an Optimol Instruments SRV tester. A flat disc bottom specimen made of standard 100Cr6 bearing steel from Optimol Instruments Prüftechnik GmbH, Westendstrasse 125, Munich, properly cleaned using a solvent, is prepared and contacted with the grease composition to be examined. The SRV test is an industry standard test and is especially relevant for CVJ grease testing. The test consists of a 10 mm diameter upper ball specimen made of 100Cr6 bearing steel alternating under load on the flat disk lower specimen indicated above. In tests to mimic tripod joints a frequency of 40 Hz with an applied load of 200 N was applied for 60 minutes (including running) at 80 ° C. The piston pulse was 1.5 mm and 3.0 mm, respectively. The coefficients of friction obtained were recorded on the computer. For each grease, the reported value is an average of four dice at the end of the tests in four runs (two runs at 1.5 mm pulse and two runs at 3.0 mm pulse). Wear is measured using a profilometer and a digital planimeter. Using the profilometer, a cross section profile can be obtained in the middle of the worn surfaces. The area (S) of this cross section can be measured using the digital planimeter. The amount of wear is evaluated by V = SI, where V is the wear volume and I is the pulse. The wear rate (Wr) is obtained by Wr = V / L [μm / m], where L is the total slip distance in the tests. For the race, it starts with an applied load of 50 N for 1 minute under the conditions specified above. Thereafter, the applied load is increased for 30 seconds by 50 N to 200 N.

The following substances are used in the examined grease compositions:

Base oil composition

The base oil compositions used have a kinematic viscosity of from about 32 to about 250 mm / s at 40 ° C and from about 5 to about 25 mm / s at about 40 ° C. Two blends of base oil are used in this invention. Base oil blend A is a mixture of one or more naphthenic oils in a range from about 10 to about 60% by weight, one or more paraffinic oils in a range from about 30 to about 80% by weight and one or more poly alpha-olefins (PAO) in a range of from about 5 to about 40% by weight, based on the total amount of the oil mixture. Oil blend A does not contain a synthetic organic ester, whereas oil blend B contains DOS in a range of from about 2 to about 10% by weight relative to a total amount of the oily mixture.

Naphthenic oils are selected with a viscosity range between about 20 and about 180 mm / s at 40 ° C, paraffinic oils between about 25 and about 400 mm 2 / s at 40 ° C and PAO between about 6 and about 40 mm / s 100 ° C.

Tri-Molecular Molybdenum Compound (TNMoS)

The tri-molecular molybdenum compound used in the grease composition according to the present invention is a sulfur-containing trinuclear molybdenum compound obtainable under the tradename C9455B from Infineum International Ltd., USA. Its structure is defined in US 6,172,013 BI.

Other molybdenum compounds for comparative examples

For comparative examples, a molybdenum dithiophosphate (MoDTP) marketed under the trade name RC3580 by Rhein Chemie Rheinau GmbH, Germany, with the chemical formula 2-ethylhexyl molybdenum dithiophosphate, diluted with mineral oil, is used. In addition, a molybdenum dithiocarbamate (MoDTC) sold under the tradename Adeka Sakur-alube 600 (S-600) in its solid state and Sakuralube 515 (S-515) in its liquid state, produced by Asahi Denka Co. Limited, is used. Japan. Other organic amide molybdenum organo complexes (Organo Mo amide), marketed under the tradename Molyvan 855 by RT Vanderbilt, USA, as well as an amine molybdenum organo complex (Organo Mo amine) traded under the tradename Sakuralube 700 (S-700), produced by Denka Co. Limited, Japan, are used.

Zinc Compound Additive

As additive zinc compounds, ZnDTP, marketed by Infineum International Ltd., UK, under the tradename Paranox-15 or marketed by Rhein Chemie, Germany, under the tradename RC3038, which is a dialkyl dithiophosphate with primary and secondary alkyl groups, are used. preferably diluted with mineral oil. In addition, ZnDTC sold under the tradename Vanlube AZ by RT are used. Vanderbilt, USA, as well as ZnO and ZnS as additive zinc compounds.

Thickener

As a lithium soap (Li soap), a reaction product of a fatty acid such as stearic or 12-hydroxostearic acid is used. In addition, a calcium complex soap (calcium complex soap) which is a product of the reaction of calcium hydroxide with two carboxylic acids, one with a short chain length of 2 to 5 carbon atoms and one with a long chain length of 16 to 20 carbon atoms, wherein the ratio of short to long chain is between 1: 2 and 1: 5.

Additions

As an antioxidant (antioxidant), a diphenylamine with butyl and / or octyl groups provided by Ciba Specialty Chemicals, Switzerland under the tradename L-57 (Irganox L57) is used. As an EP agent, a sulfurized organic compound (fatty acid methyl ester) marketed under the tradename DeoAdd MD10 by DOG Deutsche Oelfabrik, Gesellschaft fur chemische Erzeugnisse mbH und Co, Hamburg, Germany ("EP additive" in the examples) is used. Another example of an EP agent is a calcium sulfonate thickener grease as produced by Brugarolas S.A., Spain under the tradename Ca-S Grease.

As a corrosion inhibitor, a dinonolnaphthalene sulfonate calcium salt is used, distributed for example by King Industries Co. Ltd., Norwalk, CT, U.S.A under the tradename NaSuI 729 (Ca sulfonate).

First, the advantages of the grease composition according to the invention were examined by comparing the coefficient of friction and wear with other commercial organic molybdenum-containing additives (Example A). Six different grease compositions were produced as listed in Table 1 below:

Table 1

<table> table see original document page 15 </column> </row> <table>

The results of the SRV measurement of friction coefficient and wear of examples A1 to A6 can be derived from Fig. 1. Only example A1 is a grease composition according to the present invention, whereas examples A2 to A6 contain other commercial organic additives containing molybdenum (A2 to A5) or non-molybdenum containing additive (A6). The coefficient of friction, for example, Al is clearly decreased when compared to the coefficient of friction of comparative examples and is below 0.09. In addition, the measured wear of example Al is the smallest wear in the test series among examples Al to A6 and is approximately 165 μπι3 / πι.

In another series of tests, other grease compositions according to the present invention were prepared containing different concentrations of the sulfur-containing trinuclear molybdenum compound (TNMoS) 5 as listed in Table 2.

Table 2

<table> table see original document page 16 </column> </row> <table>

The SRV test results regarding friction coefficient and wear will be observed in Fig. 2.

As can be seen from Fig. 2a, surprisingly, the coefficient of friction of the grease compositions B1 to B3 is clearly approximately 0.1. Said Grease composition B1 to B3 is not in accordance with the present invention. It can be readily seen from Fig. 2a that concentrations of the sulfur-containing trinuclear molybdenum compound of 0.2 wt% or less do not significantly decrease the coefficient of friction, whereas the grease composition B4 according to the present invention has a coefficient of friction that is decreased by at least about 25% compared to examples B1 to B3. Thus, according to the present invention only an amount of the approximately 0.25% by weight sulfur-containing trinuclear molybdenum compound, relative to the total amount of the grease composition, leads to an advantageously decreased friction coefficient and values. lower for wear, as will be noted by Fig. 2b.

In a third series of tests, the effect of adding a zinc compound additive to the grease composition according to the present invention was examined by preparing the grease compositions according to Table 3.

Table 3

<table> table see original document page 17 </column> </row> <table>

The results of the SRV tests performed against examples C1 to C6 are shown in Fig. 3.

As will be seen when comparing Example C which has no zinc compound additive with Examples C2 to C6, it will be observed that especially wear is significantly decreased (cannot be measured) when a zinc compound additive is added to the composition. of grease according to the present invention. In addition, the coefficients of friction are also decreased and do not exceed the value of 0.08. Especially preferred is the addition of ZnDTP (C2 and C3) or the addition of ZnS (C6).

In addition, the effect of adding an EP agent to the grease composition according to the present invention is demonstrated by the preparation of different grease compositions according to Table 4. Table 4

<table> table see original document page 18 </column> </row> <table>

The results of the coefficient of friction and the wear measurements will be observed by Fig. 4.

The coefficient of friction is decreased by the addition of EP agents, especially by the addition of approximately 0.4 wt.% Or less of the "EP additive" EP agent, which is an organic compound marketed under the tradename DeoAdd MD10. In addition, the coefficient of friction is also decreased by the addition of the other sulfur sulfonate compounds containing Ca 1 and 2 (examples D6 to D8).

In addition, wear is decreased especially in examples D3, D7 and D8. From example D4 it can be deduced that the addition of 0.5 wt% EP additive as an EP agent does not lead to a decrease in the value for the coefficient of friction, but also provides higher values relative to the measured wear. Thus, the addition of 0.5 wt% or more of the EP additive as an EP agent should be avoided.

Finally, the effects of using different thickeners on the grease composition according to the present invention is demonstrated by the preparation of different grease compositions according to Table 5. Table 5

<table> table see original document page 19 </column> </row> <table>

The results of the SRV tests of the coefficient of friction and wear will be observed by Fig. 5.

It can be easily deduced from the coefficient of friction shown in Fig. 5 the advantageous influence of adding a sulfur-containing trinuclear molybdenum compound to a grease composition according to the present invention according to examples E1 and E3, when compares to comparative examples E2 and E4. In addition, the addition of a thickening lithium soap leads to a decrease in the coefficient of friction compared to a grease composition containing a calcium complex soap.

In summary, therefore, the grease composition according to the present invention has a significant advantageous influence on the coefficient of friction and wear, which leads to less wear and less friction in CVJ and prevents premature initiation of fatigue. bearing contact on the joint.

Claims (9)

Grease composition for use with constant speed joints, characterized in that it comprises (a) a base oil composition and (b) 0,25% by weight to 5% by weight of at least one trinuclear molybdenum compound of formula Mo3SkLnQ2 wherein L are independently selected ligands which have organo groups having a sufficient number of carbon atoms to make the compound soluble or dispersible in the oil, η is from 1 to 4, k ranges from 4 to 7, Q is selected from the group of electron donor neutral compounds such as amines, alcohols, phosphines and ethers and ζ is in the range 0 to 5 and includes non-stoichiometric values. Grease composition according to claim 1, characterized in that it also comprises at least one zinc compound additive. Grease composition according to claim 2, characterized in that it comprises at least one zinc compound additive in an amount of between 0.1% by weight and 2.5% by weight, based on the total amount. of composition. Grease composition according to claim 3, characterized in that the zinc compound is selected from the group comprising at least one of zinc dithiophosphates and / or zinc dithiocarbamates, zinc oxide and / or zinc sulfide. Grease composition according to any one of the preceding claims, characterized in that it also comprises a thickener selected from the group comprising lithium soaps, calcium soaps, lithium complex soaps, calcium complex soaps and / or urea derived thickeners. Grease composition according to any one of the preceding claims, characterized in that the base oil composition comprises poly-α-olefins, naphthenic oils, paraffinic oils and / or synthetic organic esters. Grease composition according to any one of the preceding claims, characterized in that it also comprises an additive package selected from the group of agents comprising antioxidant agents, corrosion inhibitors, anti-wear agents, friction modifiers and / or lubricating agents. extreme pressure. Grease composition according to any one of the preceding claims, characterized in that it comprises 55 wt% to 97.5 wt% of the base oil composition, 0.3 wt% to 3 wt% of the hair. least one trinuclear molybdenum compound, 0.1 wt.% to 1.5 wt.% of at least one zinc compound additive and between 2 wt.% and 25 wt.% of at least one thickener in each case relative to the amount total grease composition. Grease composition according to any one of the preceding claims, characterized in that the slip friction coefficient of the grease composition is not more than 0.1.