Use of specific base oil for reducing particulate emissions

Abstract

The present application relates to the use of a lubricant composition comprising a base oil or a mixture of base oils having a viscosity (BOV or base oil viscosity) of less than or equal to 4, for reducing the particulate emissions of an engine. The present application relates to the use of a lubricant composition comprising a base oil or a mixture of base oils, for reducing the particulate emissions of an engine, in which said base oil or said mixture of base oils has a kinematic viscosity, measured at 100°C, of less than or equal to 4.5 mm2 / s, and in which said lubricant composition has a viscosity at 150°C and under constant shear of greater than or equal to 2.4 mPa.s-1.

Description

[0001] USE OF SPECIFIC BASE OIL TO REDUCE PARTICULATE EMISSIONS The present invention relates to the use of a specific base oil to reduce particulate emissions from motor vehicles. In 1993, the first European standard on emissions from combustion engine vehicles was introduced. The Euro VI anti-pollution standard (EC 595 / 2009), which came into force on 1 September 2014 for newly approved vehicles and is applicable to all new vehicles from 1 January 2014, concerns heavy-duty engines. This standard targets four pollutants in particular: carbon monoxide (CO), unburned hydrocarbons (HC), nitrogen oxides (NOx), and the mass (PM) and number (PN) of particles, including soot, the last two remaining the most problematic for the pollution control system of modern engines. The hunt for CO2 has encouraged manufacturers to increase their efficiency in order to reduce consumption.To achieve this, lean mixture operation (excess air relative to the mass of fuel) has often been chosen. Unfortunately, this process results in a significant increase in nitrogen oxide and particulate emissions. Manufacturers have also opted in the past for the introduction of particulate filter systems in an effort to reduce the number and mass of particles emitted into the atmosphere. The operation of these systems is in most cases by burning the soot by raising the temperature of the exhaust gases at the inlet of the filter. This operation requires the presence of a catalysis. To comply with current and future standards, strict regulations on particle size and in particular on the concentration in number of particles emitted (PN) are introduced.Several studies have shown that, although particulate mass formation is low, the PN of particles emitted by compressed natural gas (CNG) engines are not negligible compared to those of diesel engines, especially under high engine load conditions. For this reason, the new Euro VI emission standards prescribe a limit of 6x10. 11particles per kWh, for heavy-duty Diesel and CNG vehicles. The use of lubricating compositions is considered to make a significant contribution to the emission of small particles (greater than 10 nm or 23 nm) emitted by this type of engine. There is an interest in providing lubricating compositions specifically adapted to reduce the number of particles emitted from the exhaust of a vehicle, in particular a vehicle comprising at least one spark-ignition engine, preferably a combustion engine, in particular heavy-duty or light vehicles, for example heavy-duty vehicles. An objective of the present invention is therefore to provide a suitable lubricating composition having a direct impact on particulate emissions. Another objective of the present invention is to provide a specific base oil allowing a lubricating composition to have a direct impact on particulate emissions.Still other objectives will become apparent upon reading the description of the invention which follows. These objectives are fulfilled by the present application which relates to the use of a lubricating composition comprising a base oil or a base oil mixture having a viscosity (BOV or base oil viscosity) of less than or equal to 4.5 mm. 2 / s, in particular less than or equal to 4 mm 2 / s, for reducing particulate emissions from an engine. The present invention also relates to the use of a lubricating composition comprising a base oil or a mixture of base oils, for reducing particulate emissions from an engine, wherein said base oil or said mixture of base oils has a kinematic viscosity (BOV or base oil viscosity) measured at 100°C, according to ASTM D445, of less than or equal to 4.5 mm 2 / s, and wherein said lubricating composition has a viscosity at 150°C and under constant shear greater than or equal to 2.4 mPa.s -1. In the context of the present invention, the term "particles" refers to the particles emitted from the exhaust of motor vehicles. This represents a set of microscopic particles (of the order of µm or less in size). These substances are varied and are included in the exhaust gases of vehicles resulting from the combustion of fuel. These substances can be solid or liquid. The term particles includes the term soot, which forms, oxidizes and contains unburned hydrocarbons, oxygenated derivatives (ketones, esters, aldehydes, lactones, ethers, organic acids) and polycyclic aromatic hydrocarbons (the famous PAHs) accompanied by their nitrated, oxygenated derivatives, etc. Mineral derivatives (SO2, sulfates, etc.) and metallic derivatives are also found.Particularly advantageously, the present invention allows the reduction of emissions of particles having a size greater than or equal to 10 nm, for example greater than or equal to 23 nm, or in particular equal to 10 nm. In the context of the present invention, the term "particle size" means particles, or agglomerates of particles whose size is between 10 and 100 nm, for example between 10 and 60 nm, and more preferably between 10 and 40 nm, for example between 23 and 100 nm, preferably between 23 and 60 nm, and more preferably between 23 and 40 nm. The particle size can in particular be measured by spectrometry, for example using a spectrometer manufactured by the company Cambustion under the commercial reference DMS500. The number of particles according to their size (PN10 or PN23) can be determined, for example, using particle counters such as the APC 489 marketed by AVL or the MEXA-2000 SPCS marketed by HORIBA.By reducing particulate emissions, we mean in particular the reduction in the number of particles, in particular particles having a size greater than or equal to 10 nm, for example greater than or equal to 23 nm. This particularly concerns the reduction in the number of particles emitted during a cycle on the WHTC regulatory cycle, for example during the WLTC or RDE cycles. This is measured as a function of the work provided on the cycle (in # / kWh). This is also measured as a function of a number of kilometers traveled. Preferably, the present application relates to the reduction of soot emissions. Preferably, the present invention relates to the reduction of particulate emissions, preferably particles having a size greater than or equal to 10 nm, for example greater than or equal to 23 nm, preferably soot, over the entire WHTC regulatory cycle for heavy goods vehicle applications (World Harmonized Transient Cycle).Preferably, the present invention relates to the reduction of the emission of particles, preferably particles with a size less than or equal to 23 nm, preferably soot, during the urban (low speed), peri-urban (moderate speed) and highway (high speed) cycles defined by the WLTC (or WLTP) (Worldwide Harmonized Light Vehicle Test Procedure) and over the entire WLTC, but also on the RDE (Real Drive Emissions) cycle. In the context of the present invention, the viscosity (also called BOV for base oil viscosity) is a kinematic viscosity and is measured at 100°C, according to the ASTM D445 standard. The viscosity of the base oil at 100°C thus corresponds to the kinematic viscosity of the base oil mixture at 100°C of the formulation before the addition of additives, a viscosity modifier and a pour point depressant.In the context of a base oil mixture it is to be understood that it is the viscosity of the base oil mixture which is less than or equal to 4. Preferably, the base oil or the base oil mixture has a viscosity of between 1.5 and 4. In the context of a base oil mixture it is to be understood that it is the viscosity of the base oil mixture which is preferably less than or equal to 4.5 mm. 2 / s. Preferably, the base oil or mixture of base oils has a kinematic viscosity, measured at 100°C, of ​​from 1.5 to 4.5 mm 2 / s, especially from 1.5 to 4 mm 2 / s. According to one embodiment, the kinematic viscosity, measured at 100°C, of ​​the base oil or the mixture of base oils is between 3 and 4.5 mm 2 / s, and preferably 4 to 4.5 mm 2 / s. Preferably, the viscosity index of the base oil or base oil blend is greater than or equal to 130, preferably greater than or equal to 150. The viscosity index is calculated by measuring the kinematic viscosity at 40°C and 100°C. These measurements are then compared to the results of two reference oils. Its method of calculation is described in ASTM D2270. The lubricating composition according to the invention has, for example, a grade according to the SAEJ300 classification of type XW-(Y) with X representing 0, 5 or 10 and Y representing an integer between 6 and 50, or between 8 and 40, preferably 12 or 30 or 40. The base oils used in the lubricating compositions of the invention may be oils of mineral or synthetic origin belonging to groups I to V according to the classes defined by the API classification (or their equivalents according to the ATIEL classification (Table 1) or their mixtures. Table 1 The mineral base oils of the invention include any type of base oil obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, deasphalting, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing. The base oils of the lubricating compositions used according to the invention may also be chosen from synthetic oils, such as certain esters of carboxylic acids and alcohols, and polyalphaolefins. The polyalphaolefins used as base oils are for example obtained from monomers comprising from 4 to 32 carbon atoms, for example from octene or decene, and for which the viscosity at 100°C is between 1.5 and 15 mm 2 .s -1according to ASTM D445. The lubricating composition used according to the invention may comprise at least 50% by weight of base oil relative to the total weight of the composition. More advantageously, the lubricating composition according to the invention comprises at least 60% by weight, or even at least 70% by weight, of base oils relative to the total weight of the lubricating composition. More preferably, the lubricating composition according to the invention comprises from 50% to 97% by weight of base oils, preferably from 50% to 85% by weight of base oils, or from 75% to 97% by weight of base oils relative to the total weight of the composition. According to one embodiment, the amount of base oil or of the mixture of base oils is from 50% to 97% by weight relative to the total weight of the lubricating composition as defined above.As mentioned above, the lubricating composition used according to the invention preferably has a viscosity at 150°C and under constant shear greater than or equal to 2.4 mPa.s. -1 . This viscosity is also referred to as HTHS 150. HTHS (High Temperature, High Shear) viscosity is a measure of the viscosity of the residual oil film under high stress (shearing under mechanical pressure) at high temperature. Here, the HTHS 150 viscosity value is measured at 150°C. These values ​​are measured according to CEC L-036-90 or ASTM D4683 standards. According to one embodiment, the viscosity at 150°C, and under constant shear, of the lubricating composition (or HTHS 150) is between 2.4 mPa.s -1 at 5 mPa.s -1 , preferably 2.6 mPa.s -1 at 5 mPa.s -1. According to one embodiment, the lubricating composition used according to the invention has a grade according to the SAEJ300 classification of type XW-(Y) with X representing 0, 5 or 10 and Y representing an integer from 6 to 50, preferably from 8 to 40, preferably 12, 20, 30 or 40, preferentially 20 or 30. The lubricating composition used according to the invention may also comprise at least one viscosity index improving additive of the hydrogenated butylene and styrene polymer type, of the ethylene propylene copolymer type, or of the polymethacrylate polymer type, preferably a hydrogenated butylene and styrene polymer.The lubricating composition according to the invention may therefore also comprise at least one viscosity index improving additive chosen from the group consisting of hydrogenated butylene and styrene polymers, ethylene propylene copolymers and polymethacrylate polymers, said viscosity index improving additive preferably being a hydrogenated butylene and styrene polymer. The lubricating composition according to the invention may comprise from 0.1% to 15% by weight relative to the total weight of lubricating composition, of viscosity index improving additive. The composition of the invention may also comprise at least one additive. Many additives may be used in the lubricating compositions according to the invention.The preferred additives for the lubricating composition according to the invention are chosen from detergent additives, friction modifying additives different from the molybdenum compounds defined above, extreme pressure additives, dispersants, pour point activators, antifoaming agents, thickeners and mixtures thereof. Preferably, the lubricating compositions according to the invention comprise at least one extreme pressure additive, or a mixture. The anti-wear additives and the extreme pressure additives protect the friction of the surfaces by forming a protective film adsorbed on its surfaces. There is a wide variety of anti-wear additives. Preferably, for the lubricating compositions of the invention, the anti-wear additives are chosen from additives comprising phosphorus and sulfur such as alkylthiophosphate metals, in particular zinc alkylthiophosphate, and more precisely zinc dialkyldithiophosphate or ZnDTP.Preferred compounds are of formula Zn((SP(S)(OR)(OR'))2, in which R and R', identical or different, independently represent an alkyl group, preferably an alkyl group comprising from 1 to 18 carbon atoms. Amine phosphates are also anti-wear additives which can be used in the lubricating compositions of the invention. However, the phosphorus atoms provided by these additives can act as a poison for the catalytic systems of automobiles since they generate ash. It is possible to minimize these effects by substituting a portion of the amine phosphates with additives which do not provide phosphorus, such as for example polysulfides, in particular olefins containing sulfur.Advantageously, the lubricating compositions according to the invention may comprise from 0.01% to 6% by weight, preferably from 0.05% to 4% by weight, more preferably from 0.1% to 2% by weight relative to the total weight of lubricating composition, of anti-wear and extreme pressure additives. Advantageously, the lubricating compositions according to the invention comprise from 0.01% to 6% by weight, preferably from 0.05% to 4% by weight, more preferably from 0.1% to 2% by weight relative to the total weight of lubricating composition, of anti-wear additives (or anti-wear compound). Advantageously, the compositions according to the invention may comprise at least one friction modifying additive other than the molybdenum compounds of the invention. The friction modifying additives may in particular be chosen from compounds providing metallic elements and ashless compounds.Among the compounds providing metallic elements, mention may be made of transition metal complexes such as Mo, Sb, Sn, Fe, Cu, Zn for which the ligands may be hydrocarbon compounds comprising oxygen, nitrogen, sulfur or phosphorus atoms. Ashless friction modifier additives are generally of organic origin or may be chosen from fatty acid monoesters and polyols, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, fatty epoxide borates, fatty amines or glycerol acid 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 may comprise from 0.01% to 2% by weight or from 0.01% to 5% by weight, preferably from 0.1% to 1.5% by weight or from 0.1% to 2% by weight relative to the total weight of the lubricating composition, of friction modifying additive other than the molybdenum compounds according to the invention. Advantageously, the lubricating composition according to the invention may comprise at least one antioxidant additive. Antioxidant additives generally delay the degradation of the lubricating composition. This degradation is most often expressed by the formation of deposits, by the presence of sludge or by an increase in the viscosity of the lubricating composition. Antioxidant additives generally act as radical inhibitors or destructive inhibitors of hydroperoxide.Commonly used antioxidants include phenolic antioxidants, amine antioxidants, and sulfur- and phosphorus-containing antioxidants. Some of these antioxidants, for example those comprising sulfur and phosphorus, may generate ash. Phenolic antioxidant additives may be ash-free or in the form of neutral or basic metal salts. Antioxidant additives may include, but are not limited to, sterically hindered phenols, sterically hindered phenol esters, sterically hindered phenols comprising a thioether bridge, diphenylamines, diphenylamines substituted with at least one C1-C12 alkyl group, N,N'-dialkylaryldiamines, and mixtures thereof.Preferably according to the invention, the sterically hindered phenols are chosen from compounds comprising a phenol group for which at least one of the carbon atoms in the vicinity of the carbon atom carrying the alcohol function is substituted by at least one C1 to C10 alkyl group, preferably a C1 to C6 alkyl group, preferably a C4 alkyl group, preferably a tert-butyl group. Amine compounds are another class of antioxidant additives which can be used, optionally in combination with phenolic antioxidant additives.Examples of amine compounds are aromatic amines, for example aromatic amines of the formula NRaRbRc in which Ra represents an aliphatic group or an aromatic group, optionally substituted, Rb represents an aromatic group, optionally substituted, Rc represents a hydrogen atom, an alkyl group, an aryl group or a group of the formula RdS(O)zRe in which Rd represents an alkylene or alkenylene group, Re represents an alkyl group, an alkenyl group or an aryl group and z represents 0, 1 or 2. Sulfur-containing alkyl phenols or their alkali or alkaline earth metal salts can also be used as antioxidant additives. Other classes of antioxidant additives are compounds containing copper, e.g. copper thio- or dithio-phosphate, copper salts of carboxylic acids, dithiocarbamates, sulfonates, phenates, copper acetylacetonates.Copper I and II salts, succinic acid or anhydride salts may also be used. The lubricating compositions used according to the invention may also comprise any type of antioxidant known to those skilled in the art. Advantageously, the lubricating composition used comprises at least one ash-free antioxidant additive. Also advantageously, the lubricating composition used according to the invention comprises from 0.1% to 2% by weight, relative to the total weight of the composition, of at least one antioxidant additive. The lubricating composition used according to the invention may 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 secondary oxidation and combustion products. The detergent additives that can be used in the lubricating compositions according to the invention are generally known to those skilled in the art.Detergent additives may be anionic compounds comprising a long lipophilic hydrocarbon chain and a hydrophobic head. The associated cation may be a metal cation of an alkali or alkaline earth metal. The detergent additives are preferably selected from alkali or alkaline earth metal salts of carboxylic acids, sulfonates, salicylates, naphthenates, and phenate salts. The alkali and alkaline earth metals are preferably calcium, magnesium, sodium, or barium. These metal salts generally comprise the metal in a stoichiometric or excess amount, i.e., in a content greater than the stoichiometric content. These are then overbased detergents; the excess metal implying the overbased nature of the detergent additive is generally in the form of an oil-insoluble metal salt, e.g., carbonate, hydroxide, oxalate, acetate, glutamate, preferably carbonate.Advantageously, the lubricating composition used according to the invention may comprise from 0.5% to 8% or from 2% to 4% by weight of overbased detergent additive relative to the total weight of the lubricating composition. Also advantageously, the lubricating composition used according to the invention may also comprise a pour point depressant additive. By slowing down the formation of paraffin crystals, the pour point depressant additive generally improves the cold behavior of the lubricating composition according to the invention. As examples of pour point depressant additives, mention may be made of alkyl polymethacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, alkyl polystyrenes. Advantageously, the lubricating composition according to the invention may also comprise a dispersing agent. The dispersing agents may be chosen from Mannich bases, succinimides and their derivatives.Also advantageously, the lubricating composition according to the invention may comprise from 0.2% to 10% by weight of dispersing agent relative to the total weight of lubricating composition. The lubricating composition according to the invention may also comprise at least one thickening agent. The lubricating composition according to the invention may also comprise an antifoaming agent and a demulsifying agent. The present invention also relates to the use of a base oil with a viscosity of less than or equal to 4 in a lubricating composition for an engine to reduce the particulate emissions of said engine. The present invention also relates to the use as defined above, in which the reduction in particulate emissions relates to the WLTC cycle or the RDE cycle, and more particularly the reduction in emissions of particles with a size greater than or equal to 10 nm, for example between 10 nm and 40 nm.The present invention also relates to a method for reducing the emission of particles in an engine, preferably a gas, gasoline, diesel or hybrid engine, comprising the use of a lubricating composition comprising a base oil with a viscosity of less than or equal to 4. The present invention also relates to a method for reducing the emission of particles in an engine, in particular a spark-ignition engine, for example a combustion engine, preferably a gas, gasoline, diesel or hybrid engine, comprising the use of a lubricating composition comprising a base oil or a mixture of base oils, in which said base oil or said mixture of base oils has a kinematic viscosity (BOV or base oil viscosity) measured at 100°C, according to the ASTM D445 standard, of less than or equal to 4.5 mm. 2 / s, and wherein said lubricating composition has a viscosity at 150°C and under constant shear greater than or equal to 2.4 mPa.s -1 The present invention also relates to a method for reducing the emission of particles in an engine, preferably a gas, gasoline, diesel or hybrid engine, lubricated by a lubricating composition comprising the addition to said lubricating composition of a base oil with a viscosity of less than or equal to 4. The present invention also relates to a method for reducing the emission of particles in an engine, preferably a gas, gasoline, diesel or hybrid engine, lubricated by a lubricating composition comprising a base oil or a mixture of base oils, in which said base oil or said mixture of base oils has a kinematic viscosity (BOV or base oil viscosity) measured at 100°C, according to standard ASTM D445, of less than or equal to 4.5 mm 2 / s, and wherein said lubricating composition has a viscosity at 150°C and under constant shear greater than or equal to 2.4 mPa.s -1 . In these methods, the particles, the base oil and the lubricating composition are as defined above. The present invention covers all motorized vehicles, in particular vehicles comprising a 2-stroke or 4-stroke engine, gasoline, diesel, hybrid or gas engines. The present invention covers all motorized vehicles, preferably comprising at least one spark-ignition engine, preferably a combustion engine, in particular heavy vehicles or light vehicles, preferably heavy goods vehicles. Package a dditif21.4 11.3 21.4 11.3 21.4 21.4Base oil 73.1 (mineral mixture of two (group III) base oils) 76.1 84.5 76 82.8 68.8 Viscosity of base oil 6 8 4 4 3 2.9 Hydrogenated butadiene styrene polymer 2.5 4.2 2.6 5.9 9.8 5.5 The characteristics of the lubricating compositions are shown in Table 3 below: Table 3 Example 2: Measurement of the number of particles emitted and Fuel Eco The compositions of Example 1 were tested on WHTC cycle and the quantity of particles with a size greater than or equal to 10 nm emitted at the end of each cycle was measured. The engine tests were carried out on turbocharged inline 6-cylinder engines. The tests are done at the same engine starting temperature. All other test bench conditions were also kept constant. Sampling for exhaust gas measurements was carried out in the raw exhaust gas before the exhaust system but after the treatment systems. Thus, the observed effects are due to the sole use of the lubricant composition and not to any other criterion such as temperature, humidity, etc. The particle size distribution was measured in parallel by a Cambustion Differential Mobility Spectrometer (DMS500).It uses a high-voltage discharge to charge each particle proportionally to its surface area. The charged particles are introduced into a classification section with a strong radial electric field. This field causes the particles to drift through a stream in a column toward the electrometer detectors. The particles are detected at different distances in the column, depending on their aerodynamic drag-to-charge ratio. The outputs of the 22 electrometers are processed in real time at 10 Hz to provide spectral data and other measurements. Fuel consumption was also measured and calculated by the following equation: Total fuel mass injected [g] ^^^^^^^^^^^^^ ^^ ^^^^^^^^^ = cycle [kWh] Particulate emissions are calculated as follows: Total number of particles [#] (^^^^^^^^^ ^^ )^^^^^^*^^ = cycle [kWh].

[0002] The results are given in Table 4 below: Table 4 These results clearly show that the choice of base oil according to the invention (viscosity less than or equal to 4) allows a clear reduction in particle emissions. These results also show that the choice of base oil according to the invention has no impact on fuel consumption (Fuel Eco), thus showing that a reduction in particle emissions is not synonymous with an improvement in Fuel Eco.

[0003] Example 3: 1 ère test campaign Preparation of lubricating compositions The lubricating compositions were prepared according to Table 5 below. Table 5 The figures in Table 5 correspond to percentages by weight relative to the total weight of the composition. The characteristics of the lubricating compositions are indicated in Table 6 below: Table 6 Measurement of the number of particles emitted The compositions of Example 3 underwent WLTC and RDE tests and the quantity of particles per kilometer traveled with a size greater than or equal to 10 nm emitted at the end of each cycle was measured. A 1.2 L EB2ADTS (PSA Peugeot Citroën) engine (maximum power of 60 kW) was used. The engine tests were carried out on turbocharged inline 3-cylinder engines. The tests are carried out at the same engine starting temperature (20°C). All other test bench conditions were also kept constant. Sampling for exhaust gas measurements was carried out in the raw exhaust gas at the outlet of the turbocharger and upstream of the aftertreatment system. The number of particles was measured using a Horiba MEXA2000-SPCS particle counter equipped with a head diluter.Each lubricant composition was tested 10 times on the WLTC cycle (with forced cooling to 20°C at the start of each cycle). The first 3 cycles were intentionally excluded to allow the injection system to stabilize. The other 7 cycles were taken into account for the results. The particle counts were expressed as the average number of particles (PN10 and PN23) per kilometer over the cycle considered. This test campaign was therefore carried out on an iso-additivation matrix. The results are shown in Tables 7 and 8 below, which concern the WLTC and RDE cycles respectively. The test of a reference oil (composition 8) covers each test. The test results are expressed relative to the result of the last reference oil used. Table 7.

[0004] Table 8 The results in Tables 7 and 8 demonstrate that the compositions used according to the invention effectively make it possible to reduce the number of particles of a size greater than or equal to 10 nm, on the WLTC or RDE cycle. Tables 9 and 10 below summarize the results obtained on the RDE or WLTC cycle for composition 8 with regard to particles of size 10 nm. These results show the repeatability of the effect of reducing the emission of PN10 particles. Table 9 Table 10 5

[0005] Example 4: 2 nde Test campaign A second test campaign was carried out. The lubricants differ in viscosity grade but also in the composition of additives and base oils. Below, in Table 11, are indicated the characteristics of the lubricant compositions which demonstrate an influence of the viscosity grade on the reduction of the PN10 number, independently of the composition: Table 10 Table 11 below shows the results obtained on the WLTC cycle for particles of size 10 nm. Table 11 These results show that the use of a lubricating composition according to the invention makes it possible to reduce the quantity of particles with a size greater than or equal to 10 nm, released into the exhaust.

Claims

CLAIMS 1. Use of a lubricating composition comprising a base oil or a mixture of base oils, for reducing particulate emissions from an engine, wherein said base oil or mixture of base oils has a kinematic viscosity (BOV or base oil viscosity) measured at 100°C, according to ASTM D445, of less than or equal to 4.5 mm 2 / s, preferably less than or equal to 4 mm 2 / s.

2. Use according to claim 1, wherein the base oil or base oil mixture has a kinematic viscosity (BOV or base oil viscosity) measured at 100°C, according to ASTM D445, less than or equal to 4.5 mm 2 / s, and wherein said lubricating composition has a viscosity at 150°C and under constant shear greater than or equal to 2.4 mPa.s -13. Use according to claim 1 or 2, wherein the viscosity index of the base oil or base oil mixture is greater than or equal to 130, preferably greater than or equal to 150.

4. Use according to any one of claims 1 to 3, wherein the particle size is greater than or equal to 10 nm, preferably equal to 10 nm.

5. Use according to any one of claims 1 to 4, wherein the kinematic viscosity, measured at 100°C, of ​​the base oil or base oil mixture is from 1.5 to 4.5 mm 2 / s, preferably 3 to 4.5 mm 2 / s, and preferably from 4 to 4.5 mm 2 / s.

6. Use according to any one of claims 1 to 5, wherein the viscosity at 150°C, and under constant shear, of the lubricating composition is 2.4 mPa·s -1 at 5 mPa.s -1 , preferably of 2.6 mPa.s -1 at 5 mPa.s -1 .

7. Use according to any one of claims 1 to 6, wherein the lubricating composition has a grade according to the SAEJ300 classification of type XW-(Y), where X represents 0, 5, or 10 and Y represents an integer from 6 to 50, preferably 20 or 30.

8. Use according to any one of claims 1 to 7, wherein the amount of base oil or base oil mixture is from 50% to 97% by weight relative to the total weight of the lubricating composition.

9. Use according to any one of claims 1 to 8, wherein the lubricating composition further comprises at least one viscosity-enhancing additive selected from the group consisting of hydrogenated butylene-styrene polymers, ethylene-propylene copolymers, and polymethacrylate polymers, said viscosity-enhancing additive preferably being a hydrogenated butylene-styrene polymer. 10.Use according to any one of claims 1 to 9, wherein the reduction of particulate emissions relates to the WLTC cycle or the RDE cycle.

11. Use of a base oil with a viscosity of 4 mm or less. 2 / s in an engine lubricant composition to reduce particulate emissions from said engine.

12. Use according to claim 11, wherein the base oil is as defined in any one of claims 2, 3, or 5.

13. Method for reducing particulate emissions in an engine, preferably a gas, gasoline, diesel, or hybrid engine, comprising the use of a lubricant composition comprising a base oil with a viscosity of 4.5 mm or less 2 / s, preferably less than or equal to 4 mm 2 / s.

14. Method for reducing particulate emissions in an engine, preferably a gas, petrol, diesel or hybrid engine, lubricated by a lubricating composition comprising the addition to said lubricating composition of a base oil with a viscosity of 4.5 mm or less 2 / s, preferably less than or equal to 4 mm 2 / s.

15. A method for reducing particulate emissions in a spark-ignition internal combustion engine, preferably a gas, gasoline, diesel, or hybrid engine, comprising the use of a lubricating composition including a base oil or a mixture of base oils, wherein said base oil or mixture of base oils has a kinematic viscosity (BOV or base oil viscosity) measured at 100°C, according to ASTM D445, of 4.5 mm or less. 2 / s, and wherein said lubricating composition has a viscosity at 150°C and under constant shear greater than or equal to 2.4 mPa.s -1 16. Method according to claim 15, wherein the lubricating composition is as defined in any one of claims 6, 7 or 9.

17. Method according to claim 15 or 16, wherein the base oil is as defined in any one of claims 2, 3, 5 or 8.

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