EP4689025A1

EP4689025A1 - Industrial gear oil

Info

Publication number: EP4689025A1
Application number: EP24717622.5A
Authority: EP
Inventors: Sneha RAWOOL; Ashok-Kumar GOYAL; Mickael Ponsardin; David KUPIEC; Grégoire ROUX
Original assignee: TotalEnergies Onetech SAS
Current assignee: TotalEnergies Onetech SAS
Priority date: 2023-03-31
Filing date: 2024-03-29
Publication date: 2026-02-11
Also published as: CN121057804A; WO2024200848A1

Abstract

The present invention relates to a lubricant composition comprising: - at least 30% by weight of at least one polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, - at least 5% by weight of at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt, based on the total weight of the lubricant composition.

Description

INDUSTRIAL GEAR OIL

FIELD OF THE INVENTION

The present invention concerns lubricant compositions for their use in the lubrification of industrial gears such as windmill gearboxes. The present invention concerns in particular compositions having improved energy efficiency and improved performances to lubricate gears, such as windmill gearboxes.

TECHNICAL BACKGROUND OF THE INVENTION

Oils for gearboxes or axles, and more generally gear oils, must satisfy numerous requirements, in particular related to the lifetime of the assembly (reduction of wear during cold shifting, no deposits and high thermal and oxidation stability, high temperature lubrication safety, stable viscosity and no shear loss situation, long life) as well as taking into account environmental aspects (reduction in oil consumption, low noise emission, easy evacuation).

Wind power generation makes use of renewable energy. Wind power generation employs wind force, and kinetic energy of wind is transformed into power thanks to rotors including propellers which are rotated by wind.

In the wind power generation, a step-up gear is employed to elevate the rotation rate of rotors, so as to improve power generation efficiency of the power generator.

The wind turbine gear box generally has a high gear ratio of about 1 :100. Thus, gears and bearings in the wind turbine generally experience high stress due to the high gear ratio.

There is a need in providing lubricant compositions for industrial applications such as windmill applications, having an improved oxidation stability and allowing high performances, in particular high energy efficiency.

SUMMARY OF THE INVENTION

The invention concerns a lubricant composition comprising: at least 30% by weight of at least one polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, at least 5% by weight of at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt, based on the total weight of the lubricant composition.

According to an embodiment, the polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt represents from 30% by weight to 78% by weight of the total weight of the lubricant composition. According to an embodiment, the ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt represents from 15% to 45% by weight of the total weight of the lubricant composition.

The inventor found that when the ethylene-propylene copolymer represents at least 15%wt of the lubricant composition, the friction coefficient, as well as the traction coefficient of the lubricant composition is further reduced in an unexpected manner.

Preferably, if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition comprises from 15 to 30%wt of the ethylene-propylene copolymer having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition.

This embodiment allows to improve the shear stability. Indeed, if the kinematic viscosity at 100°C of the ethylene-propylene copolymer is relatively high (for example higher than 1400 cSt), reducing the amount of the ethylene-propylene copolymer (for example to an amount of at most 30%wt) will allow to improve the shear stability of the resulting lubricant composition in a significant manner.

Preferably, the ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt represents at most 45% by weight, preferably at most 40% by weight of the total weight of the lubricant composition.

This embodiment allows to improve the shear stability. Indeed, reducing the amount of the ethylene-propylene copolymer (for example to an amount of at most 45%wt or at most 40%wt) will allow to improve the shear stability of the resulting lubricant composition.

According to an embodiment, the lubricant composition comprises: from 30% by weight to 78% by weight of polyalphaolefine base oil(s) having a kinematic viscosity at 100°C of less than or equal to 5 cSt, from 15% to 45% by weight of ethylene-propylene copolymer(s) having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt, based on the total weight of the lubricant composition, wherein if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition comprises from 15 to 30%wt of the ethylene-propylene copolymer having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition.

According to an embodiment, the lubricant composition comprises: from 30% by weight to 78% by weight of polyalphaolefine base oil(s) having a kinematic viscosity at 100°C of less than or equal to 5 cSt, from 15% to 45% by weight of ethylene-propylene copolymer(s) having a kinematic viscosity at 100°C ranging from 200 to 3000 cSt, based on the total weight of the lubricant composition, wherein if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition comprises from 15 to 30%wt of the ethylene-propylene copolymer having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition.

According to an embodiment, the lubricant composition of the invention comprises: from 40 to 90% by weight, preferably from 50 to 80% by weight, more preferably from 50 to 78% by weight, of one or more base oils, being understood that the lubricant composition comprises at least 30%wt of polyalphaolefine base oils having a kinematic viscosity at 100°C of less than or equal to 5 cSt, from 10 to 50% by weight, preferably from 20 to 45% by weight preferably from 22 to 45% by weight, of the ethylene-propylene copolymer,

0.1 to 20% by weight of one or more functional additive(s), preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, based on the total weight of the lubricant composition.

According to an embodiment, the lubricant composition of the invention comprises one or more of the following features:

- the ethylene-propylene copolymer has a kinematic viscosity at 100°C ranging from 300 to 5000 cSt, preferably from 400 to 4000 cSt, more preferably from 500 to 3000 cSt; and/or

- the ethylene-propylene copolymer has a weight average molecular weight ranging from 1000 to 20000 g/mol, preferably from 2000 to 18000 g/mol, more preferably from 3000 to 15000 g/mol; and/or

- the polyalphaolefine base oil is selected from polyalphaolefine base oils having a kinematic viscosity at 100°C ranging from 2 to 5 cSt; and/or

- the lubricant composition comprises at least one further functional additive, preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof; and/or

- the at least one further functional additive comprises at least one anti-wear additive and at least one antifoam additive, both additives being different from each other; and/or - the at least one further additive comprises at least one sulfur-containing additive, the at least one sulfur-containing additive can be an anti-wear additive an/or a corrosion inhibitor additive and/or an anti-oxidation additive.

According to an embodiment, the lubricant composition comprises: at least 30% by weight of at least one polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, at least 5% by weight of at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 3000 cSt, based on the total weight of the lubricant composition.

If the kinematic viscosity at 100°C of the ethylene-propylene copolymer is of at most 3000 cSt, the shear stability of the resulting lubricant composition can be further improved.

According to an embodiment, the lubricant composition of the invention comprises: from 50 to 75% by weight of base oils, from 22 to 40% by dry weight of at least one ethylene-propylene copolymer, from 1 to 20% by weight of one or more further additive(s), preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, based on the total weight of the lubricant composition, wherein preferably if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition comprises from 22 to 30%wt, of the ethylene-propylene copolymer having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition.

According to an embodiment, the lubricant composition of the invention further comprises at least one additional base oil, the additional base oil being preferably selected from PAO base oils having a kinematic viscosity at 100°C of at least 50 cSt, ester base oils, alcohol base oils, alkylated naphthalene, and mixtures thereof, more preferably from PAO base oils having a kinematic viscosity at 100°C of at least 100 cSt, ester base oils comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt, alcohol base oils comprising from 12 to 32 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 10 cSt, alkylated naphthalene having a kinematic viscosity at 100°C of less than or equal to 10 cSt, and mixture thereof.

This additional base oil will allow to improve the compatibility between the ethylene- propylene copolymer and the PAO base oil defined in the present invention. According to a preferred embodiment, the lubricant composition comprises from 1 to 10%wt, preferably from 1 to 8%wt, of an additional base oil selected from ester base oils comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt, alcohol base oils comprising from 12 to 32 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 10 cSt, and mixtures thereof, based on the total weight of the lubricant composition.

According to an embodiment, the lubricant composition of the invention comprises: at least 30% by weight of at least one PAO base oil having a kinematic viscosity of less than or equal to 5 cSt, from 3 to 30% by weight of at least one additional base oil, from 22 to 40% by dry weight of at least one ethylene-propylene copolymer, from 1 to 20% by weight of one or more further additive(s), preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, based on the total weight of the lubricant composition, wherein if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition preferably comprises from 22 to 30%wt, of the ethylene-propylene copolymer having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition, and wherein preferably at least one additional base oil is selected from ester base oils comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt, alcohol base oils comprising from 12 to 32 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 10 cSt, and mixtures thereof, and preferably said additional base oil selected from ester base oils comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt, alcohol base oils comprising from 12 to 32 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 10 cSt, and mixtures thereof, represents from 1 to 10%wt or from 1 to 8%wt of the total weight of the lubricant composition.

According to an embodiment, the lubricant composition of the invention comprises: at least 30% by weight of at least one PAO base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, from 3 to 30% by weight of at least one additional base oil, at least one additional base oil being selected from ester base oils comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt, said ester base oils representing from 1 to 8%wt of the total weight of the lubricant composition, from 22 to 40% by dry weight of at least one ethylene-propylene copolymer, from 1 to 20% by weight of one or more further additive(s), preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, based on the total weight of the lubricant composition, wherein if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition comprises from 22 to 30%wt, of the ethylenepropylene copolymer having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition.

According to an embodiment, the lubricant composition has a kinematic viscosity at 40°C ranging from 100 to 680 cSt, preferably from 150 to 460 cSt.

The invention also relates to the use of the lubricant according to the invention, to lubricate gearboxes, in particular industrial gearboxes, such as windmill gearboxes.

The invention also relates to a gearbox coated with the lubricant according to the invention.

According to an embodiment, the gearbox is selected from industrial gearboxes, preferably from windmill gearboxes.

The lubricant compositions of the invention have improved windmill gearbox performances.

The lubricant compositions of the invention allow to significantly reduce the energy consumption in gearbox.

The lubricant compositions of the invention have improved stability, in particular improved oxidation stability, and have an improved shear stability.

The lubricant compositions of the invention allow a longer drain period.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 shows the coefficient of traction of lubricant compositions at 40°C.

Fig. 2 shows the coefficient of traction of lubricant compositions at 80°C.

Fig. 3 shows the coefficient of friction of lubricant compositions at 40°C with a SRR of 5%.

Fig. 4 shows the coefficient of friction of lubricant compositions at 80°C with a SRR of 5%.

Fig. 5 shows the coefficient of friction of lubricant compositions at 40°C with a SRR of 20%. Fig. 6 shows the coefficient of friction of lubricant compositions at 80°C with a SRR of 20%.

Fig. 7 shows the coefficient of traction of lubricant compositions at 40°C.

Fig. 8 shows the coefficient of traction of lubricant compositions at 80°C.

Fig. 9 shows the coefficient of friction of lubricant compositions at 40°C with a SRR of 5%.

Fig. 10 shows the coefficient of friction of lubricant compositions at 80°C with a SRR of 5%.

Fig. 11 shows the coefficient of friction of lubricant compositions at 40°C with a SRR of 20%.

Fig. 12 shows the coefficient of friction of lubricant compositions at 80°C with a SRR of 20%.

DETAILED DESCRIPTION OF THE INVENTION

The invention is directed to a lubricant composition comprising at least one base oil and at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt.

The invention is also directed to the use of the lubricant composition defined in the invention to lubricate gearboxes, in particular industrial gearboxes, such as windmill gearboxes.

The invention is also directed to a gearbox coated with the lubricant composition defined in the invention.

The invention is also directed to the use of an ethylene-propylene copolymer in a lubricant composition for gearboxes, in particular industrial gearboxes, such as windmill gearboxes to improve oxidation stability of the lubricant composition and/or to reduce energy consumption when the lubricant composition is lubricating a gearbox, preferably an industrial gearbox, such as a windmill gearbox.

The invention is also directed to a method of lubricating windmill, the method comprising contacting at least one mechanical part of a gear such as at least a part of a windmill gearbox, with the lubricant composition defined in the invention.

The lubricant composition of the invention comprises at least 5%wt of at least one ethylene-propylene copolymer, preferably from 5 to 50%wt, more preferably from 10 to 45% by weight of the ethylene-propylene copolymer, even more preferably from 20 to 40% by weight, based on the total weight of the lubricant composition. Within the meaning of the present invention the invention, the ethylene-propylene copolymer is a copolymer obtained by copolymerization of ethylene monomers and propylene monomers. The copolymerization can be for example a bloc copolymerization or a random copolymerization.

According to an embodiment, the ethylene-propylene copolymer used in the invention consists of repetition units derived from ethylene monomers and propylene monomers.

Preferably, the ethylene-propylene copolymer has a kinematic viscosity at 100°C ranging from 300 to 5000 cSt, preferably from 400 to 4000 cSt, more preferably from 500 to 3000 cSt.

In the present invention, the kinematic viscosity can be measured according to ASTM D445 standard.

Preferably, the ethylene-propylene copolymer has a weight average molecular weight ranging from 1000 to 20000 g/mol, preferably from 2000 to 18000 g/mol, more preferably from 3000 to 15000 g/mol. The weight average molecular weight can be measured by gel permeation chromatography (GPC).

The ethylene-propylene copolymer can be synthetized according to well-known processes for the skilled person. The ethylene-propylene copolymer can also be commercially available.

Base oil(s)

The lubricant composition of the invention comprises at least 30%wt of at least one polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, preferably from 40 to 90% by weight, more preferably from 50 to 80% by weight, even more preferably from 50 to 75% by weight, relative to the total weight of the lubricant composition.

The kinematic viscosity at 100°C of the PAO base oil preferably ranges from 2 to 5 cSt. The low viscosity at 100°C of the PAO allows to further improve the energy efficiency of the lubricant composition.

The lubricant composition of the invention may further comprise one or more additional base oils. Within the meaning of the present invention, the expression “additional base oil” means a base oil that is different from the polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt.

Preferably, if they are present, the additional base oils of the lubricant composition have a kinematic viscosity at 100°C ranging from 2 to 200 cSt. These additional base oils can be selected from among base oils conventionally used in the field of lubricant oils, such as mineral oils, synthetic oils, or mixtures thereof.

It can be a mixture of several additional base oils, for example a mixture of two, three or four base oils.

The base oils and the additional base oils of the lubricant compositions of the invention can in particular be oils of mineral or synthetic origin belonging to Groups I to V of the groups defined by the API classification (or the equivalents thereof in the ATI EL classification) and are given in Table 1 below, or mixtures thereof.

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

Mixtures of synthetic and mineral oils can also be used.

The additional base oils of the compositions used in the invention can also be selected from among synthetic oils, such as polyalphaolefins (PAOs) having a kinematic viscosity higher than 5 cSt, esters of carboxylic acids and alcohols, polyalkylene glycols (PAGs) obtained by polymerization or copolymerization of alkylene oxides having 2 to 8 carbon atoms, in particular 2 to 4 carbons atoms, alcohol base oils, alkylate naphthalene base oil, and mixture thereof.

The PAOs used as base oils are obtained for example from monomers having 4 to 32 carbon atoms, for example from octene or decene. According to an embodiment, the lubricant composition comprises, based on the total weight of the lubricant composition:

- at least 30% by weight of at least one PAO base oil having a kinematic viscosity of less than or equal to 5 cSt, and

- from 0 to 30%wt, preferably from 3 to 30% by weight of at least one additional base oil, the additional base oil being for example selected from:

- PAO base oils having a kinematic viscosity at 100°C of more than 50 cSt, for example mPAO having a kinematic viscosity at 100°C ranging from 100 to 200 cSt,

- ester base oils, preferably having a kinematic viscosity at 100°C of less than or equal to 10 cSt, for example fatty esters comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt,

- alcohol base oils, preferably having a kinematic viscosity at 100°C of less than or equal to 10 cSt, for example fatty alcohol comprising from 12 to 32 carbon atoms,

- alkylated naphthalene, preferably having a kinematic viscosity at 100°C of less than or equal to 10 cSt, and mixtures thereof.

Lubricant composition

The lubricant composition defined in the present invention comprises, based on the total weight of the lubricant composition: at least 30% by weight of at least one polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, at least 5% by weight of at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt, optionally one or more functional additives.

Within the meaning of the present invention “functional additives” are additives different from the base oils and different from the ethylene-propylene copolymer.

According to an embodiment, the lubricant composition comprises, based on the total weight of the lubricant composition: at least 30% by weight of at least one polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, at least 5% by weight of at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt, optionally at least 0.1 %wt of functional additive(s).

According to an embodiment of the invention, the lubricant composition comprises, based on the total weight of the lubricant composition: at least 30% by weight of at least one polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt,

- from 15% to 45% by weight of at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt,

- from 3 to 30% by weight of at least one additional base oil, based on the total weight of the lubricant composition, wherein if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition comprises from 15 to 30%wt of the ethylene- propylene copolymer having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition.

Thus, according to this embodiment, if the ethylene-propylene copolymer has a kinematic viscosity at 100°C ranging from 200 to 1400 cSt, then the lubricant composition comprises from 15 to 45%wt of the ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 1400 cSt, based on the total weight of the lubricant composition.

Preferably, according to this embodiment, the ethylene-propylene copolymer has a kinematic viscosity at 100°C ranging from 200 to 3000 cSt.

Preferably, according to this embodiment, polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt represents from 30 to 78%wt of the total weight of the lubricant composition.

According to an embodiment, the lubricant composition comprises, based on the total weight of the lubricant composition: at least 30% by weight of at least one polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt,

- from 5% to 45% by weight of at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 3000 cSt,

- from 3 to 30% by weight of at least one additional base oil, based on the total weight of the lubricant composition, wherein if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition comprises from 5 to 30%wt of the ethylene- propylene copolymer having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition. Thus, according to this embodiment, if the ethylene-propylene copolymer has a kinematic viscosity at 100°C ranging from 200 to 1400 cSt, then the lubricant composition comprises from 5 to 45%wt of the ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 1400 cSt, based on the total weight of the lubricant composition.

Preferably, according to this embodiment, the ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 3000 cSt represents at least 15% by weight of the total weight of the lubricant composition.

According to an embodiment, the lubricant composition comprises, based on the total weight of the lubricant composition:

- from 50 to 90% by weight of one or more base oils, more preferably from 50 to 80% by weight of one or more base oils, even more preferably from 50 to 75% by weight of one or more base oils,

- from 5 to 50% by weight of the ethylene-propylene copolymer, preferably from 10 to 50% by weight of the ethylene-propylene copolymer, even more preferably from 20 to 40% by weight of the ethylene-propylene copolymer,

- optionally from 0.1 to 20% by weight of one or more functional additives, different from the ethylene-propylene copolymer, preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, the lubricant composition comprising at least 30%wt, based on the total weight of the lubricant composition, of polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt.

- from 50 to 75% by weight of one or more base oils,

- from 20 to 40% by weight of the ethylene-propylene copolymer,

- optionally from 0.1 to 20% by weight of one or more functional additives, different from the ethylene-propylene copolymer, preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, the lubricant composition comprising, based on the total weight of the lubricant composition, at least 30%wt of polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt and from 3 to 30%wt of an additional base oil (different from polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt), wherein if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition comprises from 20 to 30%wt of the ethylenepropylene copolymer having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition.

Thus, according to this embodiment, if the ethylene-propylene copolymer has a kinematic viscosity at 100°C ranging from 200 to 1400 cSt, then the lubricant composition comprises from 20 to 40%wt of the ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 1400 cSt, based on the total weight of the lubricant composition.

According to an embodiment, the lubricant composition comprises:

- from 50 to 90% by weight, more preferably from 50 to 80% by weight of base oils selected from polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt,

- optionally from 0.1 to 20% by weight of one or more functional additives, different from the ethylene-propylene copolymer, preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, based on the total weight of the lubricant composition.

According to an embodiment, the lubricant composition comprises:

- from 50 to 78% by weight of base oils selected from polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt,

- from 20 to 40% by weight of the ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt,

- optionally from 0.1 to 20% by weight of one or more functional additives, different from the ethylene-propylene copolymer, preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, based on the total weight of the lubricant composition, wherein if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition comprises from 20 to 30%wt of the ethylene- propylene copolymer having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition. Thus, according to this embodiment, if the ethylene-propylene copolymer has a kinematic viscosity at 100°C ranging from 200 to 1400 cSt, then the lubricant composition comprises from 20 to 40%wt of the ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 1400 cSt, based on the total weight of the lubricant composition.

According to an embodiment, the lubricant composition further comprises at least one functional additive, preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof.

According to an embodiment, the further additive(s) represent from 0.1 to 20%wt of the total weight of the lubricant composition, preferably from 1 to 10%wt of the total weight of the lubricant composition, more preferably from 1 to 8%wt of the total weight of the lubricant composition.

According to an embodiment, the further additive(s) comprise(s):

- at least one antiwear additive, and

- at least one antifoam additive, the antiwear additive being different from the antifoam additive.

According to an embodiment, the further additive(s) comprise(s) at least one sulfur- containing additive, preferably selected from antiwear additive(s), corrosion inhibitor additive(s), anti-oxidation additive(s) and mixtures thereof.

These additives can be added alone and/or in the form of a mixture. In particular, according to an embodiment, the additives are used in the form of an additive package. The additive package can be added into the base oil and the ethylene-propylene copolymer can be added into the base oil, before or after addition of the additive package. The additive package comprises several functional additives. The additive package can comprise all or part of the additives of the lubricant composition.

The lubricant composition implemented in the present invention may comprise at least one anti-wear and/or extreme pressure additive. Anti-wear additives and extremepressure additives protect surfaces against friction through the forming of a protective film adsorbed on these surfaces. There is a large variety of anti-wear additives. Preferably, some additives are both anti-wear and extreme-pressure additives.

Preferably, for the lubricant composition of the invention, the anti-wear additives are selected from among s ashless additives, such as alkylthiophosphate (metal free).

Amine phosphates are also anti-wear additives able to be used in a composition of the invention. A lubricant composition suitable for the invention may comprise from 0.01 to 15 % by weight, preferably 0.5 to 10% by weight, more preferably 0.5 to 5% by weight of antiwear agent(s), relative to the total weight of the composition.

A lubricant composition used in the invention may comprise at least one antioxidant additive.

The antioxidant additive generally allows delayed degradation of the composition in service. This degradation can particularly translate as the formation of deposits, the presence of sludge or an increase in the viscosity of the composition.

Antioxidant additives act in particular as radical scavengers or hydroperoxide decomposers. Among commonly employed antioxidant additives, mention can be made of antioxidant additives of phenolic type, antioxidant additives of amine type, sulfurphosphorus antioxidant additives. Some of these antioxidant additives e.g. sulfurphosphorus antioxidant additives can generate ash. Phenolic antioxidant additives can be ash-free or in the form of neutral or basic metal salts. Antioxidant additives can particular be selected from among sterically hindered phenols, sterically hindered phenol esters, and sterically hindered phenols comprising a thioether bridge, diphenylamines, diphenylamines substituted by at least one C1-C12 alkyl group, N,N'-dialkyl-aryl-diamines and mixtures thereof.

Preferably, in the invention, the sterically hindered phenols are selected from among compounds comprising a phenol group in which at least one vicinal carbon of the carbon carrying the alcohol function is substituted by at least one C1- C10 alkyl group, preferably C1-C6 alkyl group, more preferably C4 alkyl group, further preferably by the tert-butyl group.

Amine compounds are another class of antioxidant additives able to be used, optionally in combination with phenolic antioxidant additives. Examples of amine compounds are aromatic amines e.g. aromatic amines of formula NR4R5R6 where R4 is an optionally substituted aliphatic group or aromatic group, R5 is an optionally substituted aromatic group, R6 is a hydrogen atom, alkyl group, aryl group or a group of formula R7S(O)zR8 where R7 is an alkylene group or alkenylene group, R8 is an alkyl group, alkenyl group or aryl group and z is 0, 1 or 2.

Sulfurized alkyl-phenols or the alkali or alkaline-earth metal salts thereof can also be used as antioxidant additives.

Among the anti-foam additives that can be used in the lubricant composition of the invention, mention can be made of silicone compounds and polyacrylate compounds.

The anti-foam agent(s) can represent from 0.001 to 2% by weight, preferably from 0.01 to 1% by weight, of the total weight of the lubricant composition. The lubricant composition used in the invention may contain any type of antioxidant additives known to skilled persons.

Advantageously, a lubricant composition used in the invention comprises at least one ash-free antioxidant additive.

A lubricant composition used in the invention may comprise from 0.5 to 2 % by weight of at least one antioxidant additive, relative to the total weight of the composition.

Among anticorrosion additives that can be used in the lubricant composition of the invention, mention can be made of triazine-containing corrosion inhibitors, carboxylic acids and mixtures thereof.

Among carboxylic acids, mention may be made of hexanoic acid, octanoic acid or decanoic acid.

Among triazine-containing corrosion inhibitors, mention may be made of compounds comprising 1 ,3,5-triazine optionally substituted by one or more hydrocarbon groups optionally comprising heteroatoms, such as nitrogen and/or oxygen.

The corrosion inhibitor(s) can represent from 0.1 to 10% by weight, preferably from 0.1 to 3% by weight, of the total weight of the lubricant composition.

Among metal-deactivators, mention can be made of tolyltriazole, derivatives of tolyltriazole or dimercaptothiadiazoles. The metal-deactivator particularly allows neutralisation of the catalytic effect of metals such as copper and iron.

By « derivative of tolyltriazole » it is meant a tolyltriazole compound substituted preferably by one of more alkyl groups optionally comprising one or more heteroatoms.

The metal deactivator(s) can represent from 0.01 to 5% by weight, preferably from 0.02 to 2% by weight, of the total weight of the lubricant composition.

According to a preferred embodiment, the lubricant composition has a kinematic viscosity at 40°C ranging from 100 to 680 cSt, preferably from 150 to 460 cSt.

According to an embodiment, the lubricant composition of the invention comprises:

- from 40 to 90% by weight, preferably from 50 to 80% by weight, of one or more base oils, being understood that the lubricant composition comprises at least 30%wt of polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt,

- from 10 to 50% by weight, preferably from 20 to 45%wt, of at least one ethylenepropylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt, - optionally from 0.1 to 20% by weight of one or more functional additive(s), preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, based on the total weight of the lubricant composition.

- from 10 to 50% by weight, preferably from 20 to 45%wt, of at least one ethylenepropylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 4000 cSt, preferably the one ethylene-propylene copolymer has a weight average molecular weight ranging from 2000 to 15000 g/mol, based on the total weight of the lubricant composition.

According to a preferred embodiment, the lubricant composition comprises: from 40 to 90% by weight, preferably from 50 to 80% by weight, of one or more base oils, being understood that the lubricant composition comprises at least 30%wt of polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, from 10 to 50% by weight, preferably from 20 to 45%wt, of at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt, preferably the one ethylene-propylene copolymer has a weight average molecular weight ranging from 2000 to 15000 g/mol, from 0.1 to 20% by weight of one or more functional additive(s), preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, based on the total weight of the lubricant composition.

According to a preferred embodiment, the lubricant composition comprises: from 50 to 90% by weight of at least two (different) base oils, including one PAO base oil having a kinematic viscosity at 100°C ranging from 2 to 5 cSt, and one additional base oil, the additional base oil being preferably selected from PAO base oils having a kinematic viscosity at 100°C of at least 50 cSt, ester base oils, alcohol base oils, alkylated naphthalene, and mixtures thereof, being understood that the lubricant composition comprises at least 30%wt of polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, from 10 to 50% by weight of at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 10000 cSt and having a weight average molecular weight ranging from 2000 to 15000 g/mol, from 0.1 to 20% by weight of one or more functional additive(s), preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, based on the total weight of the lubricant composition.

According to a preferred embodiment, the lubricant composition comprises: from 40 to 90% by weight, preferably from 50 to 80% by weight, of one or more base oils, being understood that the lubricant composition comprises at least 30%wt of polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, from 10 to 50% by weight, preferably from 20 to 45%wt, of at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt, preferably the one ethylene-propylene copolymer has a weight average molecular weight ranging from 2000 to 15000 g/mol, from 0.5 to 10% by weight of one or more functional additive(s), preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, based on the total weight of the lubricant composition.

According to a preferred embodiment, the lubricant composition comprises: from 40 to 90% by weight, preferably from 50 to 80% by weight, of one or more base oils, being understood that the lubricant composition comprises at least 30%wt of polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, from 10 to 50% by weight, preferably from 20 to 45%wt, of at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt, preferably the one ethylene-propylene copolymer has a weight average molecular weight ranging from 2000 to 15000 g/mol, from 0.5 to 10% by weight of one or more functional additive(s), at least one additive being a sulfur-containing antiwear additive and at least one additive being an anti-foam additive, based on the total weight of the lubricant composition.

According to a preferred embodiment, the lubricant composition comprises: from 40 to 90% by weight, preferably from 50 to 80% by weight, of base oils, being understood that the lubricant composition comprises at least 30%wt of polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, from 10 to 50% by weight, preferably from 20 to 45%wt, of at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt, preferably the one ethylene-propylene copolymer has a weight average molecular weight ranging from 2000 to 15000 g/mol, from 0.5 to 10% by weight of one or more functional additive(s), at least one additive being a sulfur-containing antiwear additive and at least one additive being an anti-foam additive, based on the total weight of the lubricant composition.

According to a preferred embodiment, the lubricant composition comprises: from 50 to 78% by weight of at least two (different) base oils including one PAO base oil having a kinematic viscosity at 100°C ranging from 2 to 5 cSt, and at least one additional base oil, the additional base oil being preferably selected from PAO base oils having a kinematic viscosity at 100°C of at least 50 cSt, ester base oils, alcohol base oils, alkylated naphthalene, and mixtures thereof, from 22 to 45% by weight of the ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 10000 cSt and having a weight average molecular weight ranging from 2000 to 15000 g/mol, from 0.5 to 10% by weight of one or more functional additive(s), preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, being understood that the lubricant composition comprises at least 30%wt of polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, based on the total weight of the lubricant composition. According to a preferred embodiment, the lubricant composition comprises: from 50 to 78% by weight of at least two (different) base oils including one PAO base oil having a kinematic viscosity at 100°C ranging from 2 to 5 cSt, and at least one additional base oil, the additional base oil being preferably selected from PAO base oils having a kinematic viscosity at 100°C of at least 50 cSt, fatty esters comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt, fatty alcohol comprising from 12 to 32 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt, alkylated naphthalene, and mixtures thereof, from 22 to 45% by weight of the ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 10000 cSt and having a weight average molecular weight ranging from 2000 to 15000 g/mol, from 0.5 to 10% by weight of one or more functional additive(s), preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, being understood that the lubricant composition comprises at least 30%wt of polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, based on the total weight of the lubricant composition.

The lubricant composition can be prepared according to processes well known by the skilled person to formulate lubricant compositions, for example by mixing ingredients at a temperature ranging from 20 to 50°C.

The ethylene-propylene copolymer is used in a lubricant composition used to lubricate gearboxes, in particular industrial gearboxes, such as windmill gearboxes.

Within the meaning of the present invention, “industrial gearboxes” mean gearbox used in industries, working machines, windmill. In particular, the expression “industrial gearboxes” exclude gearboxes of vehicles.

According to an embodiment, the ethylene-propylene copolymer is used to reduce energy consumption when the lubricant composition is lubricating a gearbox, such as a windmill gearbox.

According to an embodiment, the ethylene-propylene copolymer is used to improve oxidation stability of the lubricant composition.

The inventors surprisingly found that the ethylene-propylene copolymer, when added into a lubricant composition comprising a base oil, in particular a PAO base oil, allows to reduce energy consumption and allows to improve oxidation stability of the lubricant composition.

The invention is also directed to the use of the lubricant composition defined in the invention as a gear lubricant, in particular an industrial gear lubricant, more particularly in the manufacturing, marine and/or windmill industry sectors.

In one embodiment of the invention, the lubricant composition is used in industrial gearing in windmill gearboxes.

According to an embodiment, the lubricant composition allows to reduce energy consumption when the lubricant composition is lubricating a gearbox, in particular an industrial gearbox, such as a windmill gearbox.

The invention also concerns a gear lubricating method comprising applying the lubricant composition according to the invention onto gears, wherein gears are preferably industrial gears, such as windmill gearboxes.

In one embodiment, the lubricant composition used in the lubricating method of the invention has one or more of the characteristics detailed above with regard to the use of the invention.

The invention also concerns a gear coated with the lubricant composition according to the invention.

In one embodiment, the gear is an industrial gearbox, preferably a windmill gearbox.

EXAMPLES

In the remainder of the present description, examples are given for the purpose of illustrating the present invention which are in no way intended to limit the scope thereof.

Lubricant compositions were prepared with the ingredients and amounts listed in Table 2. Table 2:

The base oil 1 comprises 70-90%wt of a PAO base oil having a viscosity at 100°C ranging from 2 to 5 cSt and 10-30%wt of additional base oil(s) selected from PAO base oils having kinematic viscosity of at least 50 cSt, fatty ester base oil comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt, and mixtures thereof, based on the total weight of the base oil 1 .

The base oil 2 comprises a PAO base oil having a viscosity at 100°C of 6 cSt, a PAO having kinematic viscosity of at least 50 cSt and fatty ester base oil comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt.

The base oil 3 comprises 90-95%wt of a PAO base oil having a viscosity at 100°C of 6 cSt and 5-10%wt of a fatty ester base oil comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt.

The EPC is an ethylene-propylene copolymer having a viscosity at 100°C of about 500-700 cSt and a weight average molecular weight from about 7900 g/mol to 11000 g/mol.

The additive package comprises additives suitable for industrial oil application, including notably sulfur-containing anti-wear additive(s), anti-corrosion additive(s) and anti-foam additive(s).

KV100 is the kinematic viscosity at 100°C of the lubricant compositions.

KV40 is the kinematic viscosity at 40°C of the lubricant compositions

Example 2: Coefficient of Traction

In this example, compositions CC1 and CI1 detailed in Table 2 were tested and the Coefficient of traction at 40°C and at 80°C was measured.

The coefficient of traction (COT) was measured using the PCS instrument MTM tribometer. It is used to evaluate the performance of lubricants in terms of friction in the mixed/hydrodynamic regime. This test consists of putting a steel ball and a steel plane in relative motion at different speeds, making it possible to define the %SRR (Slide-to-Roll Ratio) which corresponds to the sliding speed/rolling speed. The measurement conditions were 75 N load, at a rated temperature of 40°C and 80°C for a SRR from 5% to 100%.

The lower the traction coefficient for a lubricant composition, the lower the friction between the metal parts, resulting in a reduced energy consumption.

The results are provided in Fig. 1 for 40°C and in Fig. 2 for 80°C.

It can be seen from Fig. 1 and Fig. 2 that the lubricant composition of the invention shows a reduced coefficient of traction and thus a reduced energy consumption compared with composition CC1. If composition Cl 1 is compared with composition CC2, it can be seen that PAO having a viscosity at 100°C ranging from 2 to 5 cSt used in combination with an additional base oil allows to further reduce the coefficient of traction compared to a PAO having a viscosity at 100°C of 6 cSt.

Example 3: Coefficient of friction

In this example, compositions CC1 and CI1 detailed in Table 2 were tested and the Coefficient of friction at 40°C and at 80°C was measured.

The tribological properties can be evaluated by a test on a rotating ball-disk tribometer (also called ball-plane) of the Linear reciprocating tribometer type. This test makes it possible to evaluate the performance of lubricants in terms of friction in mixed/limited regime according to the conditions of load, pressure or speed applied.

The coefficient of friction of the lubricant compositions tested is determined using a hardened steel ball of approximately 2 cm diameter, for example 1.905 cm diameter, on a hardened steel plane.

The tribometer may be a device for relatively moving a steel ball and a steel plane to determine the friction/friction coefficients for a given lubricant composition, while varying various properties such as speed, load, and temperature. The hardened steel plane is AISI 52100 with a mirror finish and the ball is also AISI 52100 made of hardened steel.

The load applied is 75 N and the rolling speed varies from 5 mm/s to 2500 mm/s. In particular, the coefficient of friction is determined at a Rolling speed of 5 to 2500 mm/s, at two different temperature 40°C and at 80°C The coefficient is determined at a Slide-to-Roll Ratio (%SRR) of 5% and 20%.

Approximately 50 ml of the tested lubricant composition was introduced into the device. The ball is engaged face to face, with the ball and the plane independently actuated so as to create a mixed rolling/sliding contact.

The coefficient of friction (COF) is measured and recorded via a load cell.

The results are shown in Figs 3 to 6. Fig. 3 corresponds to the results at 40°C with a SRR of 5%.

Fig. 4 corresponds to the results at 80°C with a SRR of 5%.

Fig. 5 corresponds to the results at 40°C with a SRR of 20%.

Fig. 6 corresponds to the results at 80°C with a SRR of 20%.

It can be seen from Fig. 3, Fig. 4, Fig. 5 and Fig. 6 that the lubricant composition of the invention shows a reduced coefficient of friction and thus a reduced energy consumption.

Example 4: Effect of the amount of EPC

In this example, several compositions were prepared in order to evaluate the effect of the amount of ethylene-propylene copolymer in the lubricant composition.

Table 3 provides the details of the lubricant compositions tested in this example. The proportions are weight proportions based on the total weight of the lubricant composition.

Table 3

In Table 3: base oil 4 comprises 70-90%wt of a PAO base oil having a viscosity at 100°C ranging from 2 to 5 cSt and 10-30%wt of two additional base oils i) and ii), based on the total weight of the base oil 4, the additional base oil i) being selected from PAO base oils having kinematic viscosity at 100°C of at least 50 cSt and the additional base oil ii) being selected from fatty ester base oils comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt. base oil 5 comprises 70-90%wt of a PAO base oil having a viscosity at 100°C ranging from 2 to 5 cSt and 10-30%wt of two additional base oils i) and ii), based on the total weight of the base oil 5, the additional base oil i) being selected from PAO base oils having kinematic viscosity at 100°C of at least 50 cSt and the additional base oil ii) being selected from fatty ester base oils comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt. base oil 6 comprises 30-50%wt of a PAO base oil having a viscosity at 100°C ranging from 2 to 5 cSt and 50-70%wt of two additional base oils i) and ii), based on the total weight of the base oil 6, the additional base oil i) being selected from PAO base oils having kinematic viscosity at 100°C of at least 50 cSt and the additional base oil ii) being selected from fatty ester base oils comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt. base oil 7 comprises 30-50%wt of a PAO base oil having a viscosity at 100°C ranging from 2 to 5 cSt and 50-70%wt of two additional base oils i) and ii), based on the total weight of the base oil 7, the additional base oil i) being selected from PAO base oils having kinematic viscosity at 100°C of at least 50 cSt and the additional base oil ii) being selected from fatty ester base oils comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt.

EPC 2 is an ethylene-propylene copolymer having a viscosity at 100°C of about 2000 cSt and a weight average molecular weight from about 10500 g/mol to 15000 g/mol.

EPC and Additive package are the same as those used in Example 1.

The coefficient of traction was measured according to the method described in Example 2 and the coefficient of friction according to the method described in Example 3 were measured for these compositions of Table 3.

The traction results are provided in Fig. 7 for 40°C and in Fig. 8 for 80°C.

The friction results are shown in Figs 9 to 12.

Fig. 9 corresponds to the results at 40°C with a SRR of 5%.

Fig. 10 corresponds to the results at 80°C with a SRR of 5%.

Fig. 11 corresponds to the results at 40°C with a SRR of 20%.

Fig. 12 corresponds to the results at 80°C with a SRR of 20%.

It can be seen from Fig. 7 to Fig. 12 that an amount of about 25%wt and 34%wt of ethylenepropylene copolymer provides a reduced coefficient of traction and a reduced coefficient of friction and thus a reduced energy consumption, compared to an amount of about 12%wt of ethylene-propylene copolymer.

Example 5: Energy efficiency measurements

Table 4 shows the details of the compositions tested in this example. The proportions are expressed in weight percentage based on the total weight of the lubricant composition.

Table 4

In Table 4: base oil 8 comprises a PAO base oil having a KV100 of 40 cSt, a PAO base oil having a KV100 of 100 cSt and a fatty ester base oil comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt.

Base oil 9 comprises 46-49%wt of a PAO base oil having a viscosity at 100°C ranging from 2 to 5 cSt and 7-12% of a mPAO base oil having viscosity at 100°C ranging from 130 to 170 cSt. base oil 10 comprises PAG.

EPC is an ethylene-propylene copolymer having a viscosity at 100°C of about 500-700 cSt and a weight average molecular weight from about 7900 g/mol to 11000 g/mol.

The additive package comprises additives suitable for industrial oil application, including notably sulfur-containing anti-wear additive(s), anticorrosion additive(s) and anti-foam additive(s).

The energy efficiency of compositions of Table 4 were measured and compared with a calorimetric method. Composition CC1 corresponds to the composition CC1 of example 1. The calorimetric method involved energy efficiency determination by measuring the inlet and outlet temperature of the cooling water as well as measurement of volumetric flow rate of the cooling water. The gain is expressed in percentage compared to Ref3 used as a reference, as shown in Table 5, for different load from 40% to 100%.

Table 5

As shown in Table 5, composition CI6 provides a positive gain compared to the reference Ref3. Comparative composition CC4 provides a lower efficiency than the reference for all loads.

Thus, the compositions according to the invention have improved energy efficiency.

Example 6: Measurement of the shear stability

The tested compositions in this example are detailed in table 6.

Table 6

In table 6: base oil 9, ester base oil and EPC 3 are as detailed in relation to Table 4. EPC 2 is an ethylene-propylene copolymer having a viscosity at 100°C of about 2000 cSt and a weight average molecular weight from about 10500 g/mol to 15000 g/mol.

In this example, the shear stability of lubricant compositions of table 6 was measured using a KRL-1 test according to CEC L-45-A-99 with a load of 510 kgf, a duration of 20h, a speed of 1475 rpm, a temperature of 60°C (volume of 40 ml).

The kinematic viscosity was measured at 100°C and the percentage of loss after 20h is indicated in the table 7 below.

Table 7

As shown in Table 7, composition CI8 has a lower shear stability than composition CI7. It is noted that with an EPC having a kinematic viscosity at 100°C of more than 1400 cSt, the shear stability is greatly improved when the amount of said EPC is reduced, for example to an amount lower than 30%wt.

It can also be observed that the composition CI6 has a very good shear stability.

Claims

1. A lubricant composition comprising: at least 30% by weight of at least one polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt, at least 5% by weight of at least one ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt, based on the total weight of the lubricant composition

2. Lubricant composition according to claim 1 , wherein the polyalphaolefine base oil having a kinematic viscosity at 100°C of less than or equal to 5 cSt represents from 30% by weight to 78% by weight of the total weight of the lubricant composition.

3. Lubricant composition according to claim 1 or 2, wherein the ethylene-propylene copolymer having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt represents from 15% to 45% by weight of the total weight of the lubricant composition, being understood that if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition comprises from 15 to 30%wt of the ethylene-propylene copolymer having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition.

4. Lubricant composition according to any one of claims 1 to 3, comprising:

- from 30% by weight to 78% by weight of polyalphaolefine base oil(s) having a kinematic viscosity at 100°C of less than or equal to 5 cSt,

- from 15% to 45% by weight of ethylene-propylene copolymer(s) having a kinematic viscosity at 100°C ranging from 200 to 5000 cSt, based on the total weight of the lubricant composition, wherein if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition comprises from 15 to 30%wt of ethylene-propylene copolymer(s) having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition.

5. Lubricant composition according to any one of claims 1 to 4, comprising:

- from 40 to 90% by weight, preferably from 50 to 80% by weight, more preferably from 50 to 78% by weight, of one or more base oils, being understood that the lubricant composition comprises at least 30%wt of polyalphaolefine base oils having a kinematic viscosity at 100°C of less than or equal to 5 cSt, - from 10 to 50% by weight, preferably from 20 to 45% by weight preferably from 22 to 45% by weight, of the ethylene-propylene copolymer,

6. Lubricant composition according to any one of claims 1 to 5, wherein the ethylenepropylene copolymer has a kinematic viscosity at 100°C ranging from 300 to 5000 cSt, preferably from 400 to 4000 cSt, more preferably from 500 to 3000 cSt.

7. Lubricant composition according to any one of claims 1 to 6, wherein the ethylenepropylene copolymer has a weight average molecular weight ranging from 1000 to 20000 g/mol, preferably from 2000 to 18000 g/mol, more preferably from 3000 to 15000 g/mol.

8. Lubricant composition according to any one of claims 1 to 7, wherein the polyalphaolefine base oil is selected from polyalphaolefine base oils having a kinematic viscosity at 100°C ranging from 2 to 5 cSt.

9. Lubricant composition according to any one of claims 1 to 8, wherein the lubricant composition comprises at least one further functional additive, preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof.

10. Lubricant composition according to claim 9, wherein the at least one further functional additive comprises at least one anti-wear additive and at least one antifoam additive, both additives being different from each other.

11. Lubricant composition according to claim 9 or 10, wherein the at least one further additive comprises at least one sulfur-containing additive, the at least one sulfur- containing additive can be an anti-wear additive an/or a corrosion inhibitor additive and/or an anti-oxidation additive.

12. Lubricant composition according to any one of claims 1 to 11, comprising:

- from 50 to 75% by weight of base oils,

- from 22 to 40% by dry weight of at least one ethylene-propylene copolymer, - from 1 to 20% by weight of one or more further additive(s), preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, based on the total weight of the lubricant composition, wherein preferably if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition comprises from 22 to 30%wt, of the ethylene-propylene copolymer having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition.

13. Lubricant composition according to any one of claims 1 to 12, further comprising at least one additional base oil, the additional base oil being preferably selected from PAO base oils having a kinematic viscosity at 100°C of at least 50 cSt, ester base oils, alcohol base oils, alkylated naphthalene, and mixtures thereof, more preferably from PAO base oils having a kinematic viscosity at 100°C of at least 100 cSt, ester base oils comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt, alcohol base oils comprising from 12 to 32 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 10 cSt, alkylated naphthalene having a kinematic viscosity at 100°C of less than or equal to 10 cSt, and mixture thereof.

14. Lubricant composition according to any one of claims 1 to 13, comprising from 1 to 10%wt, preferably from 1 to 8%wt, of an additional base oil selected from ester base oils comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt, alcohol base oils comprising from 12 to 32 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 10 cSt, and mixtures thereof, based on the total weight of the lubricant composition.

15. Lubricant composition according to any one of claims 1 to 14, comprising: at least 30% by weight of at least one PAO base oil having a kinematic viscosity of less than or equal to 5 cSt,

- from 3 to 30% by weight of at least one additional base oil,

- from 22 to 40% by dry weight of at least one ethylene-propylene copolymer,

- from 1 to 20% by weight of one or more further additive(s), preferably selected from anti-wear additives, extreme-pressure additives, metal deactivators, corrosion inhibitors, anti-foam agents, anti-oxidation agents, and mixtures thereof, based on the total weight of the lubricant composition, wherein if the ethylene-propylene copolymer has a kinematic viscosity at 100°C higher than 1400 cSt, then the lubricant composition preferably comprises from 22 to 30%wt, of the ethylene-propylene copolymer having a kinematic viscosity at 100°C higher than 1400 cSt, based on the total weight of the lubricant composition, preferably at least one additional base oil is selected from ester base oils comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt, alcohol base oils comprising from 12 to 32 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 10 cSt, and mixtures thereof, and preferably said additional base oil selected from ester base oils comprising from 4 to 24 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 6 cSt, alcohol base oils comprising from 12 to 32 carbon atoms having a kinematic viscosity at 100°C of less than or equal to 10 cSt, and mixtures thereof, represents from 1 to 10%wt or from 1 to 8%wt of the total weight of the lubricant composition.

16. Lubricant composition according to any one of claims 1 to 15, having a kinematic viscosity at 40°C ranging from 100 to 680 cSt, preferably from 150 to 460 cSt.

17. Use of the lubricant according to any one of claims 1 to 16, to lubricate gearboxes, in particular industrial gearboxes, such as windmill gearboxes.

18. Gearbox coated with the lubricant according to any one of claims 1 to 16.

19. Gearbox according to claim 18, wherein the gearbox is selected from industrial gearboxes, preferably from windmill gearboxes.