EP3174960B1 - Lubricating compositions for motor vehicles - Google Patents

Description

The present invention relates to the field of lubricating compositions and base oils for motor vehicles. The invention provides a lubricating composition for an engine, gearbox or vehicle axle. This lubricating composition comprises an oil soluble polymer which is a particular polyalkylated glycol or polyalkylene glycol (PAG).

The invention also relates to the use of this lubricating composition for reducing the fuel consumption of a vehicle equipped with an engine, an axle or a gearbox lubricated by means of this lubricating composition or this PAG. particular.

Developments in engines and the performance of lubricating compositions for engines are inextricably linked. The more the engines have a complex design, the higher the efficiency and the optimization of consumption and the more the lubricating composition for the engine is required and must improve its performance.

Very high compression in the engine, higher piston temperatures, especially in the area of the upper piston ring, modern and maintenance-free valve drives with hydraulic valve lifters, as well as very high temperatures in the engine space strain increasingly lubricants for modern engines.

The conditions of use for gasoline and diesel engines include both extremely short and long journeys. In fact, 80% of car journeys in Western Europe are less than 12 kilometers while vehicles cover annual mileages of up to 300,000 km.

The oil change intervals are also very variable, from 5,000 km for some small diesel engines, they can go up to 100,000 km on diesel engines in modern commercial vehicles.

Lubricating compositions for motor vehicles must therefore have improved properties and performance.

Lubricating compositions for engines must therefore fulfill numerous objectives which are sometimes contradictory. These objectives flow from the five main functions of lubricating compositions for engines which are lubrication, cooling, sealing, anti-corrosion protection and pressure transmission.

The lubrication of the parts sliding over one another plays a decisive role, in particular in reducing friction and wear, in particular allowing fuel savings.

Another essential requirement of lubricating compositions for engines relates to environmental aspects. It has indeed become essential to reduce oil consumption as well as fuel consumption, in particular with the aim of reducing CO ₂ emissions. It is also important to reduce flue gas emissions, for example by formulating oils so that the catalyst remains fully functional throughout its lifetime. It is also important to limit or avoid the use of toxic additives in order to reduce or limit their elimination, for example by reprocessing or by combustion.

The nature of the lubricating compositions for motor vehicles has an influence on the emission of pollutants and on the fuel consumption. Lubricating compositions for motor vehicles allowing energy savings are often referred to as “fuel-eco” (FE), in English terminology. Such “fuel-eco” oils have been developed to meet these new needs.

The reduction of energy losses is therefore a constant research in the field of automotive lubricants.

For their part, gearbox or axle oils, and gear oils more generally, must meet many requirements, particularly related to driving comfort (perfect gear shifting, silent running, trouble-free operation, high reliability. ), the service life of the assembly (reduction of wear during cold passage, no deposits and high thermal stability, lubrication safety at high temperatures, stable viscosity situation and absence of shear loss, long service life) as well as the consideration of environmental aspects (lower fuel consumption, reduced oil consumption, low noise emission, easy evacuation).

These are the requirements for oils for manually operated transmissions and axle gears.

Regarding the requirements imposed on automatic gearbox oils (ATF oils for automatic transmission fluids), due to their use, very specific requirements appear for ATF oils which are a high constancy of the coefficient of friction. during the entire stay for an optimal gear change, excellent aging stability for long oil change intervals, good viscosity-temperature resistance to ensure perfect operation with a hot engine and a cold engine and compatibility of sufficient sealing with different elastomers used in transmission gaskets so that they do not swell, shrink and weaken.

Moreover, in the automotive field, the search for the reduction of CO ₂ emissions requires the development of products making it possible to reduce friction in gearboxes and in axle differentials. This reduction in friction in gearboxes and axle differentials must be achieved for different operating conditions. These friction reductions must relate to the internal friction of the lubricant but also to the friction of the components of the gearboxes or of the axle differentials, in particular the metal components.

As oils for vehicle transmission, it is possible to use refined petroleum products, hydrocracking oils or synthetic liquids, whether they are polyalphaolefins or esters. In certain cases, polyglycols are also used, which generally have the drawback of not being or not very miscible with the other base liquids.

In order to achieve sufficient performance, vehicle transmission oils must also be supplemented with additives depending on the quality requirements, in particular high pressure additives.

As regards the uses for the lubrication of vehicle engines, additives are also used.

As additives modifying the coefficient of friction, organometallic compounds, for example comprising molybdenum and in particular molybdenum sulphide, are commonly used. Mention may be made of molybdenum dithiocarbamates (MoDTC) as the major source of molybdenum. Furthermore, various (co) polymers which improve the viscosity index in a lubricating composition are also known.

WO 2013-164449 discloses an oil of PAG type resulting from the copolymerization of butylene oxide and of propylene oxide. This oil has a viscosity index of the order of 100 or 120.

US 2014-018273 discloses methylated PAG oils having a high molar mass or which comprise alkyl-ether groups.

It is necessary to provide alternative base oils, in particular oils having a high viscosity index (VI) as well as a low coefficient of traction.

The desired lubricating compositions must have a high viscosity index in order to avoid energy losses when cold due to friction but also to maintain a sufficient film of lubricant on the lubricated elements when hot.

A high viscosity index therefore guarantees less drop in viscosity when the temperature increases.

In a known manner, as lubricating compositions for vehicle engines, use is made of synthetic liquids such as polyalphaolefin (PAO) oils, esters and polyglycols; unconventional mineral oils such as hydrocracked products; conventional mineral oils; as well as their various mixtures.

Thus, in the field of bases with a high VI and low traction coefficient, as lubricating compositions for vehicle engines, mixtures of PAO oils and esters are conventionally used, for example with a proportion by mass of esters of 'around 10% ; mixtures of PAO oils and hydrocracked and hydro-isomerized oils (group III or Gp III) or mixtures of PAO oils and hydrocracked and hydro-isomerized oils with additives or even GTL base oils (gas-to -liquid or oils obtained from liquefied natural gas, for example by Fisher-Tropsch processes).

Furthermore, it is common to encounter problems of solubility when using PAGs of the state of the art. The use of PAGs of the state of the art is therefore generally limited to certain applications as industrial oils and not as oils for engines or for vehicle transmission.

There is therefore a need to provide oils and lubricating compositions for an engine or for a vehicle transmission which make it possible to provide a solution to all or part of the problems of oils or lubricating compositions of the state of the art.

dans laquelle

• ▪ R représente un groupement C₁-C₃₀-alkyl linéaire ou ramifié ;
• ▪ m et n représentent indépendamment un nombre moyen allant de 1 à 5.

Thus, the invention provides a lubricating composition comprising from 2 to 60% by weight of at least one oil of formula (I)

in which

• ▪ R represents a linear or branched _{C 1} -C _{30 -alkyl group;}
• ▪ m and n independently represent an average number ranging from 1 to 5.

Preferably, the lubricating composition according to the invention comprises at least one oil of formula (I) in which R represents a group chosen from a linear _{C 8 -alkyl group;} a branched _{C 8} -alkyl group; a linear _{C 9} -alkyl group; a branched _{C 9} -alkyl group; a linear _{C 10} -alkyl group; a branched _{C 10} -alkyl group; a linear _{C 11} -alkyl group; a branched _{C 11} -alkyl group; a linear _{C 12} -alkyl group; a branched _{C 12} -alkyl group; a linear _{C 13} -alkyl group; a branched _{C 13} -alkyl group; a linear _{C 14} -alkyl group; a branched _{C 14} -alkyl group; a linear _{C 15} -alkyl group; a branched _{C 15} -alkyl group.

More preferably, the lubricating composition according to the invention comprises at least one oil of formula (I) in which R represents a C ₈ -branched alkyl group or a linear _{C 12 -alkyl group.}

Even more preferably, the lubricating composition according to the invention comprises at least one oil of formula (I) in which R represents a linear _{C 12 -alkyl group.}

• ▪ m est supérieur ou égal à n ; ou
• ▪ m représente un nombre moyen allant de 2 à 4,5 ; ou
• ▪ n représente un nombre moyen allant de 1,5 à 4.

Also preferably, the lubricating composition according to the invention comprises at least one oil of formula (I) in which

• ▪ m is greater than or equal to n; Where
• ▪ m represents an average number ranging from 2 to 4.5; Where
• ▪ n represents an average number ranging from 1.5 to 4.

• ▪ m représente un nombre moyen allant de 2,5 à 3,5 ; ou
• ▪ n représente un nombre moyen allant de 2 à 3.

As examples of preferred lubricating compositions according to the invention, there may be mentioned a lubricating composition comprising at least one oil of formula (I) in which

• ▪ m represents an average number ranging from 2.5 to 3.5; Where
• ▪ n represents an average number ranging from 2 to 3.

• ▪ m représente un nombre moyen égal à 2,5 et n représente un nombre moyen égal à 2 ; ou
• ▪ m représente un nombre moyen égal à 3,5 et n représente un nombre moyen égal à 2,8.

As examples of particularly preferred lubricating compositions according to the invention, there may be mentioned a lubricating composition comprising at least one oil of formula (I) in which

• ▪ m represents an average number equal to 2.5 and n represents an average number equal to 2; Where
• ▪ m represents an average number equal to 3.5 and n represents an average number equal to 2.8.

• ▪ R représente un groupement C₈-alkyl ramifié, m représente un nombre moyen allant de 2 à 4,5, et n représente un nombre moyen allant de 1,5 à 4 ; ou
• ▪ R représente un groupement C₈-alkyl ramifié, m représente un nombre moyen allant de 2,5 à 3,5 et n représente un nombre moyen allant de 2 à 3.

As other examples of preferred lubricating compositions according to the invention, there may be mentioned a lubricating composition comprising at least one oil of formula (I) in which

• ▪ R represents a _{branched C 8} -alkyl group, m represents an average number ranging from 2 to 4.5, and n represents an average number ranging from 1.5 to 4; Where
• ▪ R represents a _{branched C 8} -alkyl group, m represents an average number ranging from 2.5 to 3.5 and n represents an average number ranging from 2 to 3.

• ▪ R représente un groupement C₁₂-alkyl linéaire, m représente un nombre moyen allant de 2 à 4,5, et n représente un nombre moyen allant de 1,5 à 4 ; ou
• ▪ R représente un groupement C₁₂-alkyl linéaire, m représente un nombre moyen allant de 2,5 à 3,5 et n représente un nombre moyen allant de 2 à 3.

As other examples of particularly preferred lubricating compositions according to the invention, there may be mentioned a lubricating composition comprising at least one oil of formula (I) in which

• ▪ R represents a _{linear C 12} -alkyl group, m represents an average number ranging from 2 to 4.5, and n represents an average number ranging from 1.5 to 4; Where
• ▪ R represents a _{linear C 12} -alkyl group, m represents an average number ranging from 2.5 to 3.5 and n represents an average number ranging from 2 to 3.

• ▪ R représente un groupement C₈-alkyl ramifié, m représente un nombre moyen égal à 2,5 et n représente un nombre moyen égal à 2 ; ou
• ▪ R représente un groupement C₈-alkyl ramifié, m représente un nombre moyen égal à 3,5 et n représente un nombre moyen égal à 2,8.

As examples of lubricating compositions also preferred according to the invention, there may be mentioned a lubricating composition comprising at least one oil of formula (I) in which

• ▪ R represents a _{branched C 8} -alkyl group, m represents an average number equal to 2.5 and n represents an average number equal to 2; Where
• ▪ R represents a _{branched C 8} -alkyl group, m represents an average number equal to 3.5 and n represents an average number equal to 2.8.

• ▪ R représente un groupement C₁₂-alkyl linéaire, m représente un nombre moyen égal à 2,5 et n représente un nombre moyen égal à 2 ; ou
• ▪ R représente un groupement C₁₂-alkyl linéaire, m représente un nombre moyen égal à 3,5 et n représente un nombre moyen égal à 2,8.

As examples of very particularly preferred lubricating compositions according to the invention, there may be mentioned a lubricating composition comprising at least one oil of formula (I) in which

• ▪ R represents a _{linear C 12} -alkyl group, m represents an average number equal to 2.5 and n represents an average number equal to 2; Where
• ▪ R represents a _{linear C 12} -alkyl group, m represents an average number equal to 3.5 and n represents an average number equal to 2.8.

1. (a) la viscosité cinématique à 100 °C, mesurée selon la norme ASTM D445, va de 2,5 à 4,5 mm².s^-1 ; ou dont
2. (b) l'indice de viscosité est supérieur à 160 ou est compris entre 160 et 210 ; ou dont
3. (c) le point d'écoulement est inférieur à -40 °C ; ou dont
4. (d) la viscosité dynamique (CCS) à -35 °C, mesurée selon la norme ASTM D5293 est inférieure à 1 200 mPa.s.

Preferably, the lubricating composition according to the invention comprises at least one oil of formula (I) of which

1. (a) the kinematic viscosity at 100 ° C, measured according to the ASTM D445 standard, ranges from 2.5 to 4.5 mm ² .s ^-1 ; or whose
2. (b) the viscosity index is greater than 160 or is between 160 and 210; or whose
3. (c) the pour point is less than -40 ° C; or whose
4. (d) the dynamic viscosity (CCS) at -35 ° C, measured according to ASTM D5293 is less than 1200 mPa.s.

In general according to the invention, the viscosity index is calculated according to standard ASTM D2270 and the pour point is measured according to standard EN ISO 3016.

1. (a) la viscosité cinématique à 100 °C, mesurée selon la norme ASTM D445, va de 2,5 à 4,5 mm².s^-1 ;
2. (b) l'indice de viscosité est supérieur à 160 ou est compris entre 160 et 210 ;
3. (c) le point d'écoulement est inférieur à -40 °C ;
4. (d) la viscosité dynamique (CCS) à -35 °C, mesurée selon la norme ASTM D5293 est inférieure à 1 200 mPa.s.

More preferably, the lubricating composition according to the invention comprises at least one oil of formula (I) of which

1. (a) the kinematic viscosity at 100 ° C, measured according to the ASTM D445 standard, ranges from 2.5 to 4.5 mm ² .s ^-1 ;
2. (b) the viscosity index is greater than 160 or is between 160 and 210;
3. (c) the pour point is less than -40 ° C;
4. (d) the dynamic viscosity (CCS) at -35 ° C, measured according to ASTM D5293 is less than 1200 mPa.s.

1. (a) la viscosité cinématique à 100 °C, mesurée selon la norme ASTM D445, va de 2,5 à 3,5 mm².s^-1 ; ou dont
2. (b) l'indice de viscosité est compris entre 160 et 180 ; ou dont
3. (c) le point d'écoulement est inférieur à -40 °C ; ou dont
4. (d) la viscosité dynamique (CCS) à -35 °C, mesurée selon la norme ASTM D5293 est inférieure à 500 mPa.s.

Particularly preferably, the lubricating composition according to the invention comprises at least one oil of formula (I) in which m represents an average number equal to 2.5 and n represents an average number equal to 2 and of which

1. (a) the kinematic viscosity at 100 ° C, measured according to ASTM D445, ranges from 2.5 to 3.5 mm ² .s ^-1 ; or whose
2. (b) the viscosity index is between 160 and 180; or whose
3. (c) the pour point is less than -40 ° C; or whose
4. (d) the dynamic viscosity (CCS) at -35 ° C, measured according to ASTM D5293 is less than 500 mPa.s.

1. (a) la viscosité cinématique à 100 °C, mesurée selon la norme ASTM D445, va de 2,5 à 3,5 mm².s^-1 ;
2. (b) l'indice de viscosité est compris entre 160 et 180 ;
3. (c) le point d'écoulement est inférieur à -40 °C ;
4. (d) la viscosité dynamique (CCS) à -35 °C, mesurée selon la norme ASTM D5293 est inférieure à 500 mPa.s.

Also particularly preferably, the lubricating composition according to the invention comprises at least one oil of formula (I) in which m represents an average number equal to 2.5 and n represents an average number equal to 2 and of which

1. (a) the kinematic viscosity at 100 ° C, measured according to ASTM D445, ranges from 2.5 to 3.5 mm ² .s ^-1 ;
2. (b) the viscosity index is between 160 and 180;
3. (c) the pour point is less than -40 ° C;
4. (d) the dynamic viscosity (CCS) at -35 ° C, measured according to ASTM D5293 is less than 500 mPa.s.

1. (a) la viscosité cinématique à 100 °C, mesurée selon la norme ASTM D445, va de 3,5 à 4,5 mm².s^-1 ; ou dont
2. (b) l'indice de viscosité est compris entre 180 et 210 ; ou dont
3. (c) le point d'écoulement est inférieur à -50 °C ;ou dont
4. (d) la viscosité dynamique (CCS) à -35 °C, mesurée selon la norme ASTM D5293 est inférieure à 1 200 mPa.s.

Also particularly preferably, the lubricating composition according to the invention comprises at least one oil of formula (I) in which m represents an average number equal to 3.5 and n represents an average number equal to 2.8 and of which

1. (a) the kinematic viscosity at 100 ° C, measured according to ASTM D445, ranges from 3.5 to 4.5 mm ² .s ^-1 ; or whose
2. (b) the viscosity index is between 180 and 210; or whose
3. (c) the pour point is less than -50 ° C; or whose
4. (d) the dynamic viscosity (CCS) at -35 ° C, measured according to ASTM D5293 is less than 1200 mPa.s.

1. (a) la viscosité cinématique à 100 °C, mesurée selon la norme ASTM D445, va de 3,5 à 4,5 mm².s^-1 ;
2. (b) l'indice de viscosité est compris entre 180 et 210 ;
3. (c) le point d'écoulement est inférieur à -50 °C ;
4. (d) la viscosité dynamique (CCS) à -35 °C, mesurée selon la norme ASTM D5293 est inférieure à 1 200 mPa.s.

Also particularly preferably, the lubricating composition according to the invention comprises at least one oil of formula (I) in which m represents an average number equal to 3.5 and n represents an average number equal to 2.8 and of which

1. (a) the kinematic viscosity at 100 ° C, measured according to ASTM D445, ranges from 3.5 to 4.5 mm ² .s ^-1 ;
2. (b) the viscosity index is between 180 and 210;
3. (c) the pour point is less than -50 ° C;
4. (d) the dynamic viscosity (CCS) at -35 ° C, measured according to ASTM D5293 is less than 1200 mPa.s.

• ▪ de 2 à 50 % en poids d'au moins une huile de formule (I) ; ou
• ▪ de 5 à 40 % en poids d'au moins une huile de formule (I) ; ou
• ▪ de 5 à 30 % en poids d'au moins une huile de formule (I).

Advantageously, the lubricating composition according to the invention comprises

• ▪ from 2 to 50% by weight of at least one oil of formula (I); Where
• ▪ from 5 to 40% by weight of at least one oil of formula (I); Where
• ▪ from 5 to 30% by weight of at least one oil of formula (I).

• ▪ la viscosité cinématique à 100 °C, mesurée selon la norme ASTM D445, va de 2,5 à 3,5 mm².s^-1 ;
• ▪ l'indice de viscosité est compris entre 160 et 180 ;
• ▪ le point d'écoulement est inférieur à -40 °C ;
• ▪ la viscosité dynamique (CCS) à -35 °C, mesurée selon la norme ASTM D5293 est inférieure à 500 mPa.s.

A preferred example of a lubricating composition according to the invention comprises from 5 to 40% by weight, preferably from 10 to 35% by weight or from 15 to 25% by weight, of at least one oil of formula (I) in which m represents an average number equal to 2.5 and n represents an average number equal to 2 and of which

• ▪ the kinematic viscosity at 100 ° C, measured according to the ASTM D445 standard, ranges from 2.5 to 3.5 mm ² .s ^-1 ;
• ▪ the viscosity index is between 160 and 180;
• ▪ the pour point is less than -40 ° C;
• ▪ the dynamic viscosity (CCS) at -35 ° C, measured according to standard ASTM D5293 is less than 500 mPa.s.

1. (a) la viscosité cinématique à 100 °C, mesurée selon la norme ASTM D445, va de 3,5 à 4,5 mm².s^-1 ;
2. (b) l'indice de viscosité est compris entre 180 et 210 ;
3. (c) le point d'écoulement est inférieur à -50 °C ;
4. (d) la viscosité dynamique (CCS) à -35 °C, mesurée selon la norme ASTM D5293 est inférieure à 1 200 mPa.s.

Another preferred example of a lubricating composition according to the invention comprises from 5 to 35% by weight, preferably from 8 to 30% by weight or 10% by weight, 20% by weight or 30% by weight, of at least one oil of formula (I) in which m represents an average number equal to 3.5 and n represents an average number equal to 2.8 and of which

1. (a) the kinematic viscosity at 100 ° C, measured according to ASTM D445, ranges from 3.5 to 4.5 mm ² .s ^-1 ;
2. (b) the viscosity index is between 180 and 210;
3. (c) the pour point is less than -50 ° C;
4. (d) the dynamic viscosity (CCS) at -35 ° C, measured according to ASTM D5293 is less than 1200 mPa.s.

• ▪ au moins une autre huile de base choisie parmi les huiles de groupe III, les huiles de groupe IV et les huiles de groupe V ; ou
• ▪ au moins un additif ; ou
• ▪ au moins une autre huile de base choisie parmi les huiles de groupe III, les huiles de groupe IV et les huiles de groupe V et au moins un additif.

Advantageously, the lubricating composition according to the invention also comprises

• ▪ at least one other base oil chosen from group III oils, group IV oils and group V oils; Where
• ▪ at least one additive; Where
• ▪ at least one other base oil chosen from group III oils, group IV oils and group V oils and at least one additive.

In general, the lubricating composition according to the invention can comprise any type of mineral, synthetic or natural, animal or plant lubricating base oil, suitable for their use.

The base oils used in the lubricating compositions according to the invention can be oils of mineral or synthetic origins belonging to groups I to V according to the classes defined in the API classification (or their equivalents according to the ATIEL classification) (table A). or their mixtures. <u> Table A </u> Saturated content Sulfur content Viscosity index (VI) Group I Mineral oils <90% > 0.03% 80 ≤ VI <120 Group II Hydrocracked oils ≥ 90% ≤ 0.03% 80 ≤ VI <120 Group III Hydrocracked or hydroisomerized oils ≥ 90% ≤ 0.03% ≥ 120 Grouping IV Polyalphaolefins (PAO) Grouping V Esters and other bases not included in groups I to IV

The mineral base oils according to the invention include all types of bases obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, dealphating, solvent dewaxing, hydrotreatment, hydrocracking, hydroisomerization and hydrofinishing.

Mixtures of synthetic and mineral oils can also be used.

There is generally no limitation as to the use of different lubricating bases to produce the lubricating compositions according to the invention, except that they must have properties, in particular of viscosity, viscosity index, sulfur content. , oxidation resistance, suitable for use in engines or for vehicle transmissions.

The base oils of the lubricating compositions according to the invention can also be chosen from synthetic oils, such as certain esters of carboxylic acids and alcohols, and from polyalphaolefins. The polyalphaolefins used as base oils are for example obtained from monomers comprising from 4 to 32 atoms of carbon, for example from octene or decene, and the viscosity of which at 100 ° C. is between 1.5 and 15 mm ² .s ^-1 according to standard ASTM D445. Their average molecular mass is generally between 250 and 3000 according to the ASTM D5296 standard.

Advantageously, the lubricating composition according to the invention comprises at least 50% by mass of base oils relative to the total mass of the composition.

More advantageously, the lubricating composition according to the invention comprises at least 60% by mass, or even at least 70% by mass, of base oils relative to the total mass of the composition.

More particularly advantageously, the lubricating composition according to the invention comprises from 75 to 99.9% by mass of base oils relative to the total mass of the composition.

The invention also provides a lubricating composition for vehicle engines comprising at least one lubricating composition according to the invention, at least one base oil and at least one additive.

Many additives can be used for this lubricating composition according to the invention.

The preferred additives for the lubricating composition according to the invention are chosen from detergent additives, antiwear additives, friction modifying additives, extreme pressure additives, dispersants, pour point improvers, anti-wear agents. mousse, thickeners and mixtures thereof.

Preferably, the lubricating composition according to the invention comprises at least one anti-wear additive, at least one extreme pressure additive or their mixtures.

Antiwear additives and extreme pressure additives protect rubbing surfaces by forming a protective film adsorbed on these surfaces.

There is a wide variety of antiwear additives. Preferably for the lubricating composition according to the invention, the anti-wear additives are chosen from phosphosulfur additives such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates or ZnDTP. The preferred compounds are of formula Zn ((SP (S) (OR ¹ ) (OR ² )) ₂ , in which R ¹ and R ² , identical or different, independently represent an alkyl group, preferably an alkyl group comprising from 1 to 18 carbon atoms.

Amine phosphates are also antiwear additives which can be used in the lubricating composition according to the invention. However, phosphorus provided by these additives can act as a poison in the catalytic systems of automobiles because these additives generate ash. These effects can be minimized by partially substituting the amine phosphates with additives which do not provide phosphorus, such as, for example, polysulfides, in particular sulfur-containing olefins.

Advantageously, the lubricating composition according to the invention can comprise from 0.01 to 6% by mass, preferably from 0.05 to 4% by mass, more preferably from 0.1 to 2% by mass relative to the mass total lubricant composition, antiwear additives and extreme pressure additives.

Advantageously, the lubricating composition according to the invention can comprise at least one friction modifier additive. The friction modifier additive can be chosen from a compound providing metallic elements and an ash-free compound. Among the compounds providing metallic elements, mention may be made of transition metal complexes such as Mo, Sb, Sn, Fe, Cu, Zn, the ligands of which may be hydrocarbon compounds comprising oxygen, nitrogen or carbon atoms. sulfur or phosphorus. The ash-free friction modifying additives are generally of organic origin and can be chosen from fatty acid monoesters and polyols, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, borate fatty epoxides; fatty amines or fatty acid glycerol esters. According to the invention, the fatty compounds comprise at least one hydrocarbon group comprising from 10 to 24 carbon atoms.

Advantageously, the lubricating composition according to the invention can comprise from 0.01 to 2% by mass or from 0.01 to 5% by mass, preferably from 0.1 to 1.5% by mass or from 0.1 at 2% by mass relative to the total mass of the lubricating composition, of friction modifier additive.

Advantageously, the lubricating composition according to the invention can comprise at least one antioxidant additive.

The antioxidant additive generally makes it possible to delay the degradation of the lubricating composition in service. This degradation can be reflected in particular by the formation of deposits, by the presence of sludge or by an increase in the viscosity of the lubricating composition.

Antioxidant additives act in particular as radical inhibitors or destroyers of hydroperoxides. Among the antioxidant additives commonly used, there may be mentioned antioxidant additives of phenolic type, antioxidant additives of amine type, phosphosulfurized antioxidant additives. Some of these antioxidant additives, for example phosphosulfurized antioxidant additives, can generate ash. The phenolic antioxidant additives can be ash-free or in the form of neutral or basic metal salts. The antioxidant additives can in particular be chosen from sterically hindered phenols, sterically hindered phenol esters and sterically hindered phenols comprising a thioether bridge, diphenylamines, diphenylamines substituted with at least one C _{1 -C 12} alkyl group, N , N'-dialkyl-aryl-diamines and mixtures thereof.

Preferably according to the invention, the sterically hindered phenols are chosen from compounds comprising a phenol group of which at least one carbon vicinal of the carbon carrying the alcohol function is substituted by at least one C _{1 -C 10} alkyl group, preferably one. C _{1 -C 6} alkyl group, preferably a C ₄ alkyl group, preferably through the tert-butyl group.

Amino compounds are another class of antioxidant additives that can be used, optionally in combination with phenolic antioxidant additives. Examples of amino compounds are aromatic amines, for example aromatic amines of formula NR ¹ R ² R ³ in which R ¹ represents an aliphatic group or an aromatic group, optionally substituted, R ² represents an aromatic group, optionally substituted, R ³ represents a hydrogen atom, an alkyl group, an aryl group or a group of formula R ⁴ S (O) _z R ⁵ in which R ⁴ represents an alkylene group or an alkenylene group, R ⁵ represents an alkyl group, a alkenyl group or an aryl group and z represents 0, 1 or 2.

Sulfurized alkyl phenols or their alkali and alkaline earth metal salts can also be used as antioxidant additives.

Another class of antioxidant additives is that of copper compounds, for example copper thio- or dithio-phosphates, copper and carboxylic acid salts, dithiocarbamates, sulphonates, phenates, copper acetylacetonates. Copper I and II salts, salts of succinic acid or anhydride can also be used.

The lubricating composition according to the invention can contain all types of antioxidant additives known to those skilled in the art.

Advantageously, the lubricating composition comprises at least one antioxidant additive free of ash.

Also advantageously, the lubricating composition according to the invention comprises from 0.5 to 2% by weight, relative to the total mass of the composition, of at least one antioxidant additive.

The lubricating composition according to the invention can also comprise at least one detergent additive.

Detergent additives generally make it possible to reduce the formation of deposits on the surface of metal parts by dissolving the by-products of oxidation and combustion.

The detergent additives which can be used in the lubricating composition according to the invention are generally known to those skilled in the art. Detergent additives can be anionic compounds comprising a long lipophilic hydrocarbon chain and a hydrophilic head. The associated cation can be a metal cation of an alkali or alkaline earth metal.

The detergent additives are preferably chosen from alkali metal or alkaline earth metal salts of carboxylic acids, sulphonates, salicylates, naphthenates, as well as salts of phenates. The alkali metals and alkaline earth metals are preferably calcium, magnesium, sodium or barium.

These metal salts generally include the metal in a stoichiometric amount or else in excess, therefore in an amount greater than the stoichiometric amount. These are then overbased detergent additives; the excess metal providing the overbased character to the detergent additive is then generally in the form of a metal salt insoluble in oil, for example a carbonate, a hydroxide, an oxalate, an acetate, a glutamate, preferably a carbonate .

Advantageously, the lubricating composition according to the invention can comprise from 2 to 4% by weight of detergent additive relative to the total mass of the lubricating composition.

Also advantageously, the lubricating composition according to the invention can also comprise at least one pour point reducing additive.

By slowing down the formation of paraffin crystals, the pour point lowering additives generally improve the cold behavior of the lubricating composition according to the invention.

As an example of pour point lowering additives, mention may be made of polymethacrylates of alkyl, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, alkylated polystyrenes.

Advantageously, the lubricating composition according to the invention can also comprise at least one dispersing agent.

The dispersing agent can be chosen from Mannich bases, succinimides and their derivatives.

Also advantageously, the lubricating composition according to the invention can comprise from 0.2 to 10% by mass of dispersing agent relative to the total mass of the lubricating composition.

Advantageously, the lubricating composition can also comprise at least one additional polymer improving the viscosity index. This additional polymer is generally different from the oil soluble polymer chosen from polyalkylene glycols (PAG).

As examples of additional polymer improving the viscosity index, mention may be made of polymer esters, homopolymers or copolymers, hydrogenated or non-hydrogenated, of styrene, butadiene and isoprene, and polymethacrylates (PMA).

Also advantageously, the lubricating composition according to the invention can comprise from 1 to 15% by mass relative to the total mass of the lubricating composition of oil-soluble polymer chosen from polyalkylene glycols (PAG) and of this additional polymer improving the viscosity index.

The lubricating composition according to the invention can be in different forms. The lubricating composition according to the invention can in particular be an anhydrous composition. Preferably, this lubricating composition is not an emulsion.

The invention also relates to the use of the lubricating composition according to the invention for reducing the fuel consumption of an engine, in particular of a vehicle engine.

The invention also relates to the use of the lubricating composition according to the invention for reducing the traction coefficient of a vehicle engine oil.

The invention also relates to the use of the lubricating composition according to the invention for reducing the fuel consumption of a vehicle equipped with an axle or a gearbox lubricated by means of this composition.

The invention also relates to the use of the lubricating composition according to the invention for reducing the fuel consumption of a vehicle equipped with a transmission lubricated by means of this composition.

The invention also relates to the use of the lubricating composition according to the invention for reducing the traction coefficient of a transmission oil, in particular of a gearbox oil or of a axle oil.

The invention also relates to the use of at least one oil of formula (I) according to the invention for improving the Fuel Eco (FE) of a lubricant.

The invention also relates to the use of at least one oil of formula (I) according to the invention for reducing the fuel consumption of an engine, in particular of a vehicle engine.

The invention also relates to the use of at least one oil of formula (I) according to the invention for reducing the traction coefficient of a vehicle engine oil.

The invention also relates to the use of at least one oil of formula (I) according to the invention for reducing the fuel consumption of a vehicle equipped with a axle or a gearbox lubricated by means of this. oil.

The invention also relates to the use of at least one oil of formula (I) according to the invention for reducing the fuel consumption of a vehicle equipped with a transmission lubricated by means of this oil.

The invention also relates to the use of at least one oil of formula (I) according to the invention for reducing the traction coefficient of a transmission oil, in particular of a gearbox oil or of a gearbox oil. deck oil.

According to the invention, the oil of formula (I) and the lubricating composition can be used for lubricating a vehicle engine.

These uses of the lubricating composition according to the invention or of the oil of formula (I) comprise the contacting of at least one element of the engine, of the transmission, in particular of the gearbox or of the axle, with a lubricating composition according to the invention or else with an oil of formula (I).

By analogy, the particular, advantageous or preferred characteristics of the oil of formula (I) according to the invention or of the lubricating composition according to the invention define particular, advantageous or preferred uses according to the invention.

dans laquelle

• ▪ R représente un groupement C₁-C₃₀-alkyl linéaire ou ramifié ;
• ▪ m et n représentent indépendamment un nombre moyen allant de 1 à 5.

Described is also a method of preparing the lubricating composition according to the invention from at least one oil of formula (I)

in which

• ▪ R represents a linear or branched _{C 1} -C _{30 -alkyl group;}
• ▪ m and n independently represent an average number ranging from 1 to 5.

The oil of formula (I) is generally prepared from an initiator alcohol of formula R-OH mixed with a solution of an alkali or alkaline earth metal hydroxide. As the initiating alcohol, 2-ethyl-hexanol and dodecanol are preferred. As the alkali or alkaline earth metal hydroxide, potassium hydroxide is preferred.

Under an inert atmosphere, a mixture of at least one initiator alcohol and at least one alkaline earth metal hydroxide is heated to a temperature which may range from 80 to 130 ° C, for example approximately 115 ° C.

Then, the water present in the medium is removed, for example by flash evaporation, in order to limit the presence of water, for example at a concentration of less than 0.1% by weight. Then, 1,2-propylene oxide and 1,2-butylene oxide are introduced at a temperature which can range from 90 to 150 ° C, for example about 130 ° C, and at a pressure which can range from 90 to 150 ° C, for example approximately 130 ° C. range from 350 to 550 kPa. Stir and leave to act for 5 to 25 hours.

Then, the residual catalyst is separated, for example by filtration through magnesium silicate.

dans laquelle

• ▪ R représente un groupement C₁-C₃₀-alkyl linéaire ou ramifié ;
• ▪ m et n représentent indépendamment un nombre moyen allant de 1 à 5.

An intermediate product of formula (II) is obtained

in which

• ▪ R represents a linear or branched _{C 1} -C _{30 -alkyl group;}
• ▪ m and n independently represent an average number ranging from 1 to 5.

Then, the intermediate product of formula (II) is reacted in the presence of a solution of an alkali metal or alkaline earth metal alkoxide in an alcohol, for example methanol, at a temperature which may range from 80 to 140 ° C, for example at 120 ° C., and at reduced pressure, for example less than 1 kPa, and under an inert atmosphere. As the alkali metal or alkaline earth alkoxide, sodium methoxide is preferred.

An alkyl halide is added and left to act, under an inert atmosphere, at a temperature which may range from 50 to 130 ° C, for example 80 ° C, at a pressure which may range from 120 to 350 kPa, for example 260 kPa, and for 5 to 25 hours. As the alkyl halide, methyl chloride is preferred.

The mixture is stirred and left to act for 15 min to 15 hours, for example for 1.5 hours, and at a temperature which may range from 50 to 130 ° C., for example 80 ° C.

Then, the alkyl ether formed and the unreacted alkyl halide are separated, for example by flash evaporation. The alkali or alkaline earth metal halide is washed, for example with water.

The aqueous saline phase is separated, for example by decantation. Then, the residual water is separated, for example with magnesium silicate and flash evaporation.

The mixture can be left to cool and then filtered, for example with magnesium silicate, to obtain the oil of formula (I)

The oil of formula (I) can be incorporated with one or more other base oils and one or more additives to form the lubricating composition according to the invention.

The various aspects of the invention are illustrated by the examples which follow.

Example 1: preparation of a PAG oil of formula (I) according to the invention - oil (1)

valeurs moyennes: m = 3,53 et n = 2,84

mean values: m = 3.53 and n = 2.84

In a stainless steel autoclave reactor, dodecanol (2647 g) is introduced as initiator, followed by a 45% solution by mass of potassium hydroxide (28.2 g). The mixture is heated to 115 ° C. under a nitrogen atmosphere.

Then, the water is removed by flash evaporation (115 ° C, 3 MPa) to a water concentration of less than 0.1% by weight.

A mixture of 1,2-propylene oxide (2910 g) and 1,2-butylene oxide (2910 g) is introduced into the reactor at a temperature of 130 ° C and at a pressure of 490 kPa. . The mixture is stirred and left to act for 14 hours at 130 ° C.

The residual catalyst is separated by filtration through magnesium silicate at 50 ° C to obtain the intermediate product (A) whose kinematic viscosity measured at 40 ° C according to the ASTM D445 standard is 22.4 mm ² .s ^-1 , the kinematic viscosity measured at 100 ° C according to the ASTM 445 standard is 4.76 mm ² .s ^-1 , the viscosity index is 137 and the pour point is -48 ° C.

Product (A) (8266 g) is introduced into a stainless steel autoclave reactor. A solution of sodium methoxide at 25% by mass in methanol (3060 g) is added and the mixture is stirred (180 revolutions per minute) at 120 ° C for 12 hours at reduced pressure (less than 1 kPa) with a nitrogen flow (200 mL per minute).

Methyl chloride (751 g) is added at 80 ° C. and under pressure (260 kPa).

The mixture is stirred and left to act for 1.5 hours at 80 ° C.

Then, a flash evaporation is carried out (10 min, 80 ° C., at reduced pressure) to separate the dimethyl ether and the unreacted methyl chloride.

Water (2,555 g) was added followed by stirring for 40 minutes at 80 ° C to wash the sodium chloride from the mixture. Stirring is stopped and left to stand for 1 hour at 80 ° C.

The aqueous saline phase (3283 g) is separated by decantation, magnesium silicate (50 g) is added to the remaining mixture and a flash evaporation is carried out (1 hour, 100 ° C., at a pressure of less than 1 kPa) under a flow of nitrogen (200 mL per minute) and with stirring (180 revolutions per minute) in order to separate the residual water.

The mixture was allowed to cool to 60 ° C and then filtered through magnesium silicate at 50 ° C to separate the oil (1) (8,359 g). The yield of the methylation step is 98.6% by mass.

For this oil (1), the kinematic viscosity measured at 40 ° C according to the ASTM D445 standard is 14.4 mm ² .s ^-1 , the kinematic viscosity measured at 100 ° C according to the ASTM D445 standard is 3.98 mm ² .s ^-1 and the pour point measured according to ISO 3016 is -54 ° C.

The viscosity index of this oil is 194 and its dynamic viscosity (CCS) at -35 ° C, measured according to the ASTM D5293 standard, is 1120 mPa.s.

Example 2: preparation of a PAG oil of formula (I) according to the invention - oil (2)

valeurs moyennes: m = 2,45 et n = 1,97

mean values: m = 2.45 and n = 1.97

Dodecanol (2369 g) is introduced into a stainless steel autoclave reactor, followed by a 45% solution by mass of potassium hydroxide (20.02 g). The mixture is heated to 115 ° C. under a nitrogen atmosphere. Flash evaporation (115 ° C and 3 MPa) of the mixture is carried out to separate the water. The water concentration of the mixture is reduced to less than 0.1% by mass.

A mixture of 1,2-propylene oxide (1808.5 g) and 1,2-butylene oxide (1808.5 g) is introduced into the reactor at a temperature of 130 ° C and at a pressure of 490 kPa. The mixture is stirred and left to act for 14 hours at 130 ° C.

The residual catalyst is separated by filtration through magnesium silicate at 50 ° C to obtain the intermediate product (B) whose kinematic viscosity measured at 40 ° C according to the ASTM D445 standard is 16.1 mm ² .s ^-1 , the kinematic viscosity measured at 100 ° C according to the ASTM D445 standard is 3.7 mm ² .s ^-1 and the pour point is -39 ° C.

Product (B) (5,797 g) is introduced into a stainless steel autoclave reactor. A solution of sodium methoxide at 25% by mass in methanol (2765 g) is added and the mixture is stirred (180 revolutions per minute) at 120 ° C for 12 hours at reduced pressure (less than 1 kPa) with a nitrogen flow (200 mL per minute).

Part of the mixture (3825 g) is emptied from the reactor.

Then, in the other part of the mixture (2264 g) which remained in the reactor, methyl chloride (252 g) is added at 80 ° C. and under pressure (260 kPa).

The mixture is stirred and left to act for 1.5 hours at 80 ° C.

Then, a flash evaporation is carried out (10 min, 80 ° C., at reduced pressure) to separate the dimethyl ether and the unreacted methyl chloride.

Water (796 g) was added followed by stirring for 40 minutes at 80 ° C to wash the sodium chloride from the mixture. Stirring is stopped and left to stand for 1 hour at 80 ° C.

The aqueous saline phase (961 g) is separated by decantation, magnesium silicate (50 g) is added to the remaining mixture and a flash evaporation is carried out (1 hour, 100 ° C, at pressure less than 1 kPa) under a flow nitrogen (200 mL per minute) and with stirring (180 revolutions per minute).

The mixture is allowed to cool to 60 ° C and then filtered through magnesium silicate at 50 ° C to separate the oil (2) (2218 g). The yield of the methylation step is 93.7% by mass.

For this oil (2), the kinematic viscosity measured at 40 ° C according to the ASTM D445 standard is 9.827 mm ² .s ^-1 , the kinematic viscosity measured at 100 ° C according to the ASTM D445 standard is 2.97 mm ² .s ^-1 and the pour point measured according to ISO 3016 is -48 ° C.

The viscosity index of this oil is 172 and its dynamic viscosity (CCS) at -35 ° C, measured according to the ASTM D5293 standard, is 450 mPa.s.

Comparative Example 3: Preparation of a Known PAG Oil - Comparative Oil (1)

valeurs moyennes: m = 1,76 et n = 1,42

mean values: m = 1.76 and n = 1.42

Dodecanol (4,364 g) is introduced into a stainless steel autoclave reactor, followed by a 45% solution by mass of potassium hydroxide (39.68 g). The mixture is heated to 115 ° C. under a nitrogen atmosphere.

Flash evaporation (115 ° C and 3 MPa) of the mixture is carried out to separate the water. The water concentration of the mixture is reduced to 0.1% by mass.

1,2-propylene oxide (2276 g) and 1,2-butylene oxide (2276 g) are introduced into the reactor at a temperature of 130 ° C and a pressure of 370 kPa. . The mixture is stirred and left to act for 12 hours at 130 ° C.

The residual catalyst is separated by filtration through magnesium silicate at 50 ° C to obtain the comparative oil (1) whose kinematic viscosity measured at 40 ° C according to the ASTM D445 standard is 12.2 mm ² .s ^{- 1} , the kinematic viscosity measured at 100 ° C according to ASTM D445 is 3.0 mm ² .s ^-1 and the pour point is -29 ° C. The viscosity index of this oil is 60 and its dynamic viscosity (CCS) at -35 ° C, measured according to the standard ASTM D5293, is 4090 mPa.s.

Comparative Example 4: Preparation of a Known PAG Oil - Comparative Oil (2)

valeurs moyennes: m = 2,79 et n = 2,25

mean values: m = 2.79 and n = 2.25

In a stainless steel autoclave reactor, dodecanol (3141 g) is introduced as initiator, followed by a 45% solution by mass of potassium hydroxide (38.4 g). The mixture is heated to 115 ° C. under a nitrogen atmosphere. Flash evaporation (115 ° C and 3 MPa) of the mixture is carried out to separate the water. The water concentration of the mixture is reduced to 0.1% by mass.

A mixture of 1,2-propylene oxide (2,735.5 g) and 1,2-butylene oxide (2,735.5 g) is introduced into the reactor at a temperature of 130 ° C. and at a pressure of 370 kPa. The mixture is stirred and left to act for 12 hours at 130 ° C.

The residual catalyst is separated by filtration through magnesium silicate at 50 ° C to obtain the comparative oil (2) whose kinematic viscosity measured at 40 ° C according to the ASTM D445 standard is 18.0 mm ² .s ^{- 1} , the kinematic viscosity measured at 100 ° C according to ASTM D445 is 4.0 mm ² .s ^-1 and the pour point is -41 ° C.

The viscosity index of this comparative oil (2) is 116 and its dynamic viscosity (CCS) at -35 ° C, measured according to the standard ASTM D5293, is 3250 mPa.s.

Example 5: Preparation of lubricating compositions according to the invention, of comparative lubricating compositions and evaluation of the properties of these compositions for the lubrication of the transmission of a motor vehicle

The lubricating compositions are prepared by mixing the oil (2) according to Example 2 and known oils with other base oils and with additives for the preparation of lubricating compositions according to the amounts (% by mass) of Table 1 . <u> Table 1 </u> Composition (1) according to the invention Composition (2) according to the invention Comparative composition (1) base oil group III (KV100 / ASTM D445 = 3) 20.0 / 40.75 base oil group III (KV100 / ASTM D445 = 4) 41.75 43.3 41.0 oil (2) according to the invention 20.0 38.45 / viscosity index improving additive (polymethacrylate - PMA) 6.0 6.0 6.0 viscosity improving additive (polyethylene-polypropylene - PEPP) 5.0 5.0 5.0 mixture of additives (dispersant, detergent, antioxidant, extreme pressure agent, anti-wear, anti-foam) 7.0 7.0 7.0 friction reducing additive (organo-molybdenum) 0.2 0.2 0.2 silicone anti-foam additive 0.05 0.05 0.05

The characteristics of the lubricating compositions prepared are evaluated and the results obtained are presented in Table 2. <u> Table 2 </u> Composition (1) according to the invention Composition (2) according to the invention Comparative composition (1) viscosity index (ISO 2909) 197 205 185 traction coefficient (MTM:
T = 40 ° C, V _e = 1 m / s, SRR = 20% load = 75 N) 0.045 0.043 0.053 Difference in energy efficiency compared to a commercial oil 0.20 0.21 0.06 oxidation resistance (CEC 1517) (160 ° C - 192 h) variation KV 40 (%) -5.0 8.6 21.01 variation KV100 (%) 5.4 4.3 18.95 change in TAN (mg KOH / g) 0.23 0.22 1.3 amount of insoluble matter (% by mass) 0.0012 0.0032 0.004 elastomer compatibility variation in hardness for RE1 fluorocarbon 2 1 3 RE2 polyacrylate ACM 1 -3 -2 HNBR1 -1 -3 1 75FKM595 8 9 ND 4-ball wear test (4B4 PSA D55-1078 / RENAULT D55 1994) wear diameter (mm) 0.80 0.74 0.73 4 ball extreme pressure test (4B6 ASTM D551136) 0.47 0.46 ND wear diameter before seizing (mm) - last load before seizing (kg) 90 90 ND wear diameter at first seizure (mm) 1.36 0.87 ND - first systematic seizing load (kg) 120 120 ND ND: not available

The energy efficiency is evaluated by comparison with a commercial gearbox oil based on group III oils (KV100 = 7.46 mm ² .s ^-1 , KV40 = 33.97 mm ² .s ^-1 , VI = 196). The difference in energy efficiency between the compositions evaluated and this commercial oil is measured.

This test therefore makes it possible to evaluate the fuel efficiency and to quantify the efficiency of the gearbox used by comparing the output torque with the input torque. It is thus possible to evaluate the Fuel Eco property of the gearbox oils used.

In this test, a five-speed manual transmission was used. The oil temperatures are 20 ° C and 50 ° C. They allow oils to be clearly distinguished by their Fuel Eco properties, in particular when cold (20 ° C). The input torque is fixed at 30 Nm then at 90 Nm. The input speed is fixed at 1000 rpm then at 3000 rpm. For each oil temperature and for each gear ratio, the operating conditions are shown in Table B. <u> Table B </u> Oil temperature (° C) Box report Input torque (Nm) Input speed (rpm) 20 R2 30 1000 90 3000 30 1000 90 3000 R3 30 1000 90 3000 30 1000 90 3000 50 R4 30 1000 90 3000 30 1000 90 3000 R5 30 1000 90 3000 30 1000 90 3000

This test makes it possible to simulate a European NEDC test and to determine the CO ₂ emission and fuel consumption of a gearbox lubricated with a particular oil. The higher the efficiency value, the better the reduction in fuel consumption.

Thus, it is observed that compared with a lubricating composition comprising two oils from group III of the state of the art, the lubricating compositions comprising the oil (2) according to the invention exhibit improved properties.

The viscosity index is much higher. The traction coefficient is lowered by at least 7%. The energy yield is also greatly improved and allows a gain more than 3 times greater than a composition based on a commercial oil based on group III oils. These parameters therefore make it possible to demonstrate the Fuel Eco gain of the composition according to the invention.

The lubricating compositions according to the invention also have an oxidation resistance which is of the same level or even greater than that of the lubricating composition of the state of the art. Their compatibility with the various elastomers which can be used in the transmission seals with which they are in contact is also at the same level or even better than that of the lubricating composition of the state of the art.

In addition, the compositions according to the invention allow good resistance to wear of the mechanical parts of a transmission for an automobile.

Finally, it is observed that the improvements in the properties of the lubricating composition comprising 20% of oil (2) according to the invention are of the same order or even greater than those of the lubricating composition comprising 38.45% of oil (2) according to l 'invention.

Example 6: Preparation of lubricating compositions according to the invention, of comparative lubricating compositions and evaluation of the properties of these compositions for the lubrication of a vehicle engine

The lubricating compositions are prepared by mixing the oil (1) according to Example 1 and known oils with other base oils and with additives for the preparation of lubricating compositions according to the amounts (% by mass) of Table 3 . <u> Table 3 </u> Composition (3) according to the invention Composition (4) according to the invention Comparative composition (2) base oil group III (KV100 / ASTM D445 = 4.16 mm ² .s ^-1 ) 45.45 37.45 37.45 base oil group III: Neste Nexbase 3050 29.0 17.3 15.0 base oil group IV PAO (KV100 / ASTM D445 = 4.08 mm ² .s ^-1 ) / / 30.0 oil (1) according to the invention 8.0 27.7 / mixture of additives (dispersants, detergent, DTPZn, amino antioxidant, phenolic antioxidant) 10.9 10.9 10.9 viscosity index improving additive (hydrogenated polyisoprene-styrene - PISH) 3.2 3.2 3.2 viscosity index improving additive (PMA) 2.9 2.9 2.9 friction reducing additive (MoDTC) 0.5 0.5 0.5 amine type anti-corrosion additive 0.05 0.05 0.05

The characteristics of the lubricating compositions prepared are evaluated and the results obtained are presented in Table 4. <u> Table 4 </u> Composition (3) according to the invention Composition (4) according to the invention Comparative composition (2) viscosity index (ISO 2909) 192 202 190 Noack volatility (CEC L-40-93) (%) 10.3 9.5 10.4 dynamic viscosity (CCS) at -35 ° C (ASTM D5293) (mPa.s) 6,790 4 970 4 970 resistance to oxidation (method GFC Lu-36-T-03) (170 ° C - 144 h) KV100 variation after 144 h (ISO 3405) (%) -13.7 -10.6 -6.74 change in TAN after 144 h (ASTM D664) (mg KOH / g) 3.1 4.8 7.1 change in PAI after 144 h (ASTM D7214) (A.cm ^-1 .mm ^-1 ) 55 173 102 detergency - overall rating 1 (average) (CEC M-02-A-78) (merit / 10) 6.0 5.4 5.5 elastomer compatibility variation in hardness for RE1 fluorocarbon ND 0 0 RE2 polyacrylate ACM ND 1 4 RE3 silastic MCQ ND -22 -21 RE4 nitril HNBR ND 0 1 ND: not available

Compared with a lubricating composition comprising two oils from group III and one oil from group IV of the state of the art, the lubricating compositions comprising the oil (1) according to the invention exhibit improved properties.

The viscosity index is higher, or even much higher, and the Noack volatility is improved. These parameters therefore make it possible to demonstrate the “Fuel-Eco” gain of the composition according to the invention.

The lubricating compositions according to the invention also have an oxidation resistance which is greater than that of the lubricating composition of the state of the art. The detergency of the lubricating compositions according to the invention is at the same level or even better than that of the lubricating composition of the state of the art.

The compatibility of the lubricating compositions according to the invention with the various elastomers which can be used in the transmission seals with which they are in contact is also at the same level or even better than that of the lubricating composition of the state of the art.

Finally, it is observed that the improvements in the properties of the lubricating composition comprising 8% of oil (1) according to the invention are of the same order or even greater than those of the lubricating composition comprising 27.7% of oil (1) according to l 'invention.

Example 7: preparation of a lubricating compositions according to the invention, of a comparative lubricating composition and evaluation of the properties of these compositions for the lubrication of a vehicle engine

The lubricating compositions are prepared by mixing the oil (1) according to Example 1 and known oils with other base oils according to the amounts (% by mass) of Table 5. A comparative lubricating composition (3) is also prepared from a comparative oil (2) according to comparative example (3). <u> Table 5 </u> Composition (5) according to the invention Comparative composition (3) base oil group III (KV100 / ASTM D445 = 4.16 mm ² .s ^-1 ) 37.45 37.45 base oil group III: Neste Nexbase 3050 17.3 17.3 oil (1) according to the invention 27.7 / comparative oil (2) / 27.7 mixture of additives (dispersants, detergent, DTPZn, amino antioxidant, phenolic antioxidant) 10.9 10.9 viscosity index improving additive (PISH) 3.2 3.2 viscosity index improving additive (PMA) 2.9 2.9 friction reducing additive (MoDTC) 0.5 0.5 amine type anti-corrosion additive 0.05 0.05

The characteristics of the lubricating compositions prepared are evaluated and the results obtained are presented in Table 6. <u> Table 6 </u> Composition (5) according to the invention Comparative composition (3) kinematic viscosity measured at 100 ° C (ASTM D445) (mm ² .s ^-1 ) 9.672 9.858 viscosity index (ISO 2909) 202 193 Noack volatility (CEC L-40-93) (%) 9.5 12.3 dynamic viscosity (CCS) at -35 ° C (ASTM D5293) (mPa.s) 4 970 6,250

Compared with a lubricating composition comprising two oils from group III and the comparative oil (2) of the state of the art, the lubricating composition comprising the oil (1) according to the invention exhibits improved properties.

The kinematic viscosity measured at 100 ° C is lower. The dynamic viscosity (CCS at -35 ° C.) is lower, which highlights an improvement in the cold behavior of the composition according to the invention.

In addition, the viscosity index is much higher and the Noack volatility is greatly improved. These parameters therefore make it possible to demonstrate the “Fuel-Eco” gain of the composition according to the invention.

Example 8: preparation of a lubricating composition according to the invention, of a comparative lubricating composition and evaluation of the properties of these compositions for the lubrication of a vehicle engine

The lubricating compositions are prepared by mixing the oil (1) according to Example 1 and known oils with other base oils and with additives for the preparation of lubricating compositions according to the amounts (% by mass) in Table 7. . <u> Table 7 </u> Composition (6) according to the invention Comparative composition (4) base oil group III (KV100 / ASTM D445 = 4.38 mm ² .s ^-1 ) 48.7 48.7 base oil group IV PAO (KV100 / ASTM D445 = 4.08 mm ² .s ^-1 ) 20.0 20.0 oil (1) according to the invention 10.0 / comparative oil (2) / 10.0 mixture of additives (dispersants, detergent, DTPZn, amino antioxidant, phenolic antioxidant) 12.6 12.6 friction modifier additive (glycerol monooleate) 0.5 0.5 pour point improver additive (PMA) 0.2 0.2 viscosity index improving additive (PISH) 8.0 8.0

The characteristics of the lubricating compositions prepared are evaluated and the results obtained are presented in Table 8. <u> Table 8 </u> Composition (6) according to the invention Comparative composition (4) viscosity index (ISO 2909) 195 192 kinematic viscosity measured at 100 ° C (ISO 31404) (mm ² .s ^-1 ) 8,115 8.043 dynamic viscosity (CCS) at -35 ° C (ASTM D5293) (mPa.s) 4,480 4,950 basicity index (total base number: TBN) (ASTM D2896) 7.3 7.8 oxidation resistance (Daimler oxidation test FO - DIN 51453) (100 ° C - 168 h) (%) -9.1 -13.3 oxidation resistance (Daimler oxidation test 5% B100 - DIN 51453) (100 ° C - 168 h) (%) 18.8 14.2 Fuel Eco (W24 C250 CDI / engine - OM651 vs MB RL002) (%) 3.84 2.62

Compared with a lubricating composition comprising a group III oil, a group IV oil and the comparative oil (2) of the state of the art, the lubricating composition comprising the oil (1) according to the invention exhibits properties. improved, and more particularly in “Fuel-Eco” gain.

The viscosity index is higher. The dynamic viscosity (CCS at -35 ° C) is lower. The resistance to oxidation is improved.

Example 9: preparation of a lubricating composition according to the invention, of a comparative lubricating composition and evaluation of the properties of these compositions for lubricating the transmission of a motor vehicle

The lubricating compositions are prepared by mixing the oil (2) according to Example 2 and known oils with other base oils and with additives for the preparation of lubricating compositions according to the amounts (% by mass) of Table 9 . <u> Table 9 </u> Composition (7) according to the invention Comparative composition (5) base oil group IV mPAO (KV100 / ASTM D445 = 3.5 mm ² .s ^-1 ) 55 55 oil (2) according to the invention 16.3 / comparative oil (1) / 16.3 viscosity index improving additive (PMA) 6.0 6.0 viscosity index improving additive (PMA) 14.0 14.0 mixture of additives (dispersants, detergent, antioxidant, extreme pressure agent, anti-wear, anti-foam, DTPZn) 8.7 8.7

The characteristics of the lubricating compositions prepared are evaluated and the results obtained are presented in Table 10. <u> Table 10 </u> Composition (7) according to the invention Comparative composition (5) viscosity index (ISO 2909) 212 200 traction coefficient (MTM: T = 40 ° C, V _e = 1 m / s, SRR = 20% load = 75 N) 0.036 0.041

Compared with a lubricating composition comprising a group IV oil and the comparative oil (1) of the state of the art, the lubricating composition comprising the oil (2) according to the invention exhibits improved properties.

The viscosity index is much higher and the tensile coefficient is lowered by more than 12%. These parameters therefore make it possible to demonstrate the “Fuel-Eco” gain of the composition according to the invention.

Claims (15)

1. A lubricating composition comprising from 2 to 60% by weight of at least one oil of formula (I)

   

   wherein

   ▪ R represents a linear or branched C₁-C₃₀ alkyl group;

   ▪ m and n represent independently an average number ranging from 1 to 5.
2. The lubricating composition according to claim 1 for which R represents a group selected from among a linear C₈ alkyl group; a branched C₈ alkyl group; a linear C₉ alkyl group; a branched C₉ alkyl group; a linear C₁₀ alkyl group; a branched C₁₀ alkyl group; a linear C₁₁ alkyl group; a branched C₁₁ alkyl group; a linear C₁₂ alkyl group; a branched C₁₂ alkyl group; a linear C₁₃ alkyl group; a branched C₁₃ alkyl group; a linear C₁₄ alkyl group; a branched C₁₄ alkyl group; a linear C₁₅ alkyl group; a branched C₁₅ alkyl group.
3. The lubricating composition according to one of claims 1 or 2 for which

   ▪ m is greater than or equal to n; or

   ▪ m represents an average number ranging from 2 to 4.5; or

   ▪ n represents an average number ranging from 1.5 to 4.
4. The lubricating composition according to one of claims 1 to 3 for which

   ▪ m represents an average number ranging from 2.5 to 3.5; or

   ▪ n represents an average number ranging from 2 to 3.
5. The lubricating composition according to one of claims 1 to 4 for which

   ▪ m represents an average number equal to 2.5 and n represents an average number equal to 2; or

   ▪ m represents an average number equal to 3.5 and n represents an average number equal to 2.8.
6. The lubricating composition according to one of claims 1 to 5 comprising at least one oil of formula (I) for which

   (a) the kinematic viscosity at 100°C, measured according to the ASTM D445 standard, ranges from 2.5 to 4.5 mm².s^-1; or for which

   (b) the viscosity index is greater than 160 or is comprised between 160 and 210; or for which

   (c) the pour point is less than -40°C; or for which

   (d) the dynamic viscosity (CCS) at -35°C, measured according to the ASTM D5293 standard is less than 1,200 mPa.s.
7. The lubricating composition according to one of claims 1 to 6, comprising at least one oil of formula (I) for which

   (a) the kinematic viscosity at 100°C, measured according to the ASTM D445 standard, ranges from 2.5 to 4.5 mm².s^-1;

   (b) the viscosity index is greater than 160 or is comprised between 160 and 210;

   (c) the pour point is less than -40°C;

   (d) the dynamic viscosity (CCS) at -35°C, measured according to the ASTM D5293 standard is less than 1,200 mPa.s.
8. The lubricating composition according to one of claims 1 to 7, comprising at least one oil of formula (I) wherein m represents an average number equal to 2.5 and n represents an average number equal to 2 and for which

   (a) the kinematic viscosity at 100°C, measured according to the ASTM D445 standard, ranges from 2.5 to 3.5 mm².s^-1;

   (b) the viscosity index is comprised between 160 and 180;

   (c) the pour point is less than -40°C;

   (d) the dynamic viscosity (CCS) at -35°C, measured according to the ASTM D5293 standard is less than 500 mPa.s.
9. The lubricating composition according to one of claims 1 to 7, comprising at least one oil of formula (I) wherein m represents an average number equal to 3.5 and n represents an average number equal to 2.8 and for which

   (a) the kinematic viscosity at 100°C, measured according to the ASTM D445 standard, ranges from 3.5 to 4.5 mm².s^-1;

   (b) the viscosity index is comprised between 180 and 210;

   (c) the pour point is less than -50°C;

   (d) the dynamic viscosity (CCS) at -35°C, measured according to the ASTM D5293 standard is less than 1,200 mPa.s.
10. The lubricating composition according to one of claims 1 to 9, comprising from 2 to 50% by weight of at least one oil of formula (I).
11. The lubricating composition according to one of claims 8 or 10, comprising from 5 to 40% by weight of at least one oil of formula (I).
12. The lubricating composition according to one of claims 9 or 10, comprising from 5 to 35% by weight of at least one oil of formula (I).
13. The lubricating composition according to one of claims 1 to 12, also comprising

    ▪ at least one other base oil selected from oils of group III, oils of group IV and oils of group V; or

    ▪ at least one additive; or

    ▪ at least one other base oil selected from oils of the group III, oils of group IV and oils of group V and at least one additive.
14. The use of at least one lubricating composition according to one of claims 1 to 13

    ▪ for reducing the fuel consumption of an engine; or

    ▪ for reducing the fuel consumption of a vehicle equipped with a transmission lubricated by means of this composition.
15. The use of at least one lubricating composition according to one of claims 1 to 13 for reducing the traction coefficient of a transmission oil.