USE OF A SPECIFIC BASE OIL TO REDUCE PARTICULATE EMISSIONS

Abstract

USE OF A SPECIFIC BASE OIL FOR REDUCING PARTICULATE EMISSIONS The present application 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, 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 lubricating composition has a viscosity at 150°C and under constant shear of greater than or equal to 2.4 mPa.s-1. Figure for abstract: none

Description

Title of the invention: USE OF A SPECIFIC BASE OIL TO REDUCE PARTICLE EMISSIONS

[0001] The present invention relates to the use of a specific base oil for reducing particulate emissions from motor vehicles.

[0002] 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 will apply to all new vehicles from 1 January 2014, concerns heavy goods vehicle 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 latter two remain the most problematic for the pollution control system of modern engines.

[0003] The hunt for CO2 has encouraged manufacturers to increase their efficiency in order to reduce consumption. To achieve this, they have often opted for lean mixture operation (excess air in relation to the mass of fuel). Unfortunately, this process results in a significant increase in nitrogen oxide and particulate emissions.

[0004] 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 a combustion of soot by an increase in the temperature of the exhaust gases at the inlet of the filter. This operation requires the presence of a catalysis.

[0005] To comply with current and future standards, strict regulations on particle size and in particular on the particle number concentration (PN) of emitted particles are introduced. Several studies have shown that, although the formation of particulate mass is low, the PN of particles emitted by spark-ignition engines and compressed natural gas (CNG) engines are not negligible compared to those of diesel engines, particularly under high engine load conditions.

[0006] For this reason, the new Euro VI emission standards prescribe a limit of 6x10" particles per kWh, for heavy-duty Diesel and CNG vehicles.

[0007] The use of lubricating composition 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.

[0008] 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 combustion engine, in particular heavy or light vehicles.

[0009] An objective of the present invention is therefore to provide a suitable lubricating composition having a direct impact on particle emissions.

[0010] 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.

[0011] Still other objectives will appear on reading the description of the invention which follows.

[0012] These objectives are fulfilled by the present application which 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, 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, less than or equal to 4.5 mm2 / s, and in which said lubricating composition has a viscosity at 150°C and under constant shear greater than or equal to 2.4 mPa.s *.

[0013] 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 pm 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.

[0014] In a particularly advantageous manner, 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.

[0015] In the context of the present invention, the term "particle size" means particles, or agglomerates of particles, whose size is from 10 nm to 100 nm, for example from 10 nm to 100 nm, preferably from 10 nm to 60 nm, and more preferably from 10 nm to 40 nm.

[0016] The size of the particles 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.

[0017] By reducing particle 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, or even preferably particles having a size equal to 10 nm. This particularly concerns the reduction in the number of particles emitted during the WLTC or RDE cycles. This is measured as a function of the number of kilometers traveled.

[0018] Preferably, the present application relates to the reduction of soot emissions.

[0019] Preferably, the present invention relates to the reduction of the emission of particles, preferably particles of size less than or equal to 23 nm, preferably soot, during the urban (low speed), peri-urban (moderate speed) and road (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.

[0020] 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.

[0021] In the context of a base oil mixture, it should be understood that it is the viscosity of the base oil mixture which is less than or equal to 4.5 mm2 / s.

[0022] Preferably, the base oil or the mixture of base oils has a kinematic viscosity, measured at 100°C, of ​​from 1.5 to 4.5 mm2 / s, in particular from 1.5 to 4 mm2 / s.

[0023] 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 mm2 / s, and preferably between 4 and 4.5 mm2 / s.

[0024] Preferably, wherein 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.

[0025] 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 calculation method is described in the ASTM D2270 standard.

[0026] 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 classification ATIEL (Table 1) or their mixtures.

[0027] [Tables 1] Saturated substance content Sulphur 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 Hydro-isomerized oils >90% < 0.03% > 120 Group IV Polyalphaolefins (PAO) Group V Esters and other bases not included in groups I to IV

[0028] 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.

[0029] 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 mm2.s 1 according to standard ASTM D445.

[0030] The lubricating composition used according to the invention may comprise at least 50% by weight of base oil(s) relative to the total weight of said 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 oil(s) 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 oil(s), preferably from 50 to 85% by weight of base oil(s), or from 75 to 97% by weight of base oil(s) relative to the total weight of the composition.

[0031] According to one embodiment, the amount of base oil or mixture of base oils is from 50% to 97% by weight relative to the total weight of the lubricating composition as defined above.

[0032] As mentioned above, the lubricating composition used according to the invention has a viscosity at 150°C and under constant shear greater than or equal to 2.4 mPa.s'. This viscosity is also designated by the term HTHS 150.

[0033] 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 viscosity value 150 is measured at 150°C. These values ​​are measured according to CEC L-036-90 or ASTM D4683 standards.

[0034] According to one embodiment, the viscosity at 150°C, and under constant shear, of the lubricating composition (or HTHS 150) is from 2.4 mPa.s 1 to 5 mPa.s ', preferably from 2.6 mPa.s 1 to 5 mPa.s '.

[0035] 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.

[0036] 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.

[0037] The lubricating composition used according to the invention may also comprise at least one additive.

[0038] Many additives can be used in the lubricating compositions according to the invention.

[0039] The preferred additives for the lubricating composition used 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 depressants, anti-foaming agents, thickeners and mixtures thereof.

[0040] Preferably, the lubricating compositions used according to the invention comprise at least one extreme pressure additive, or a mixture.

[0041] Anti-wear additives and extreme pressure additives protect surface friction by forming a protective film adsorbed on its surfaces.

[0042] There is a wide variety of anti-wear additives. Preferably, for the lubricating compositions used according to 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. The 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.

[0043] Amine phosphates are also anti-wear additives that can be used in the lubricating compositions used according to 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 that do not provide phosphorus, such as, for example, polysulfides, in particular olefins containing sulfur.

[0044] Advantageously, the lubricating compositions used 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.

[0045] Advantageously, the lubricating compositions used 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).

[0046] Advantageously, the compositions used according to the invention may comprise at least one friction modifying additive different from 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. The ashless friction modifying 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 comprising at least one hydrocarbon group comprising from 10 to 24 carbon atoms.

[0047] Advantageously, the lubricating composition used according to the invention may comprise from 0.01% to 2% by weight or from 0.01% to 5% by weight, preferably 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.

[0048] Advantageously, the lubricating composition used according to the invention may comprise at least one antioxidant additive.

[0049] 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.

[0050] Antioxidant additives generally act as radical inhibitors or hydroperoxide destructive inhibitors. Commonly used antioxidants include phenolic antioxidants, amine antioxidants, 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 in particular be chosen from sterically hindered phenols, sterically hindered phenol esters, sterically hindered phenols comprising a thioether bridge, diphenylamines, diphenylamines substituted with at least one C1 to C12 alkyl group, N,N'-dialkylaryldiamines, and mixtures thereof.

[0051] 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.

[0052] Amine compounds are another class of antioxidant additives that can be used, optionally in combination with phenolic antioxidant additives. Examples of amine compounds are aromatic amines, for example aromatic amines of 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 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.

[0053] Sulfur-containing alkylphenols or their alkali or alkaline earth metal salts can also be used as antioxidant additives.

[0054] Other classes of antioxidant additives are compounds comprising copper, for example example 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 can also be used.

[0055] The lubricating compositions used according to the invention may also comprise any type of antioxidant known to those skilled in the art.

[0056] Advantageously, the lubricating composition used according to the invention comprises at least one ash-free antioxidant additive.

[0057] 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.

[0058] The lubricating composition used according to the invention may also comprise at least one detergent additive.

[0059] 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.

[0060] The detergent additives that can be used in the lubricating compositions according to the invention are generally known to those skilled in the art. The 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.

[0061] The detergent additives are preferably chosen from alkali or alkaline earth metal salts of carboxylic acid, sulfonates, salicylates, naphthenates, as well as phenate salts. The alkali and alkaline earth metals are preferably calcium, magnesium, sodium or barium.

[0062] These metal salts generally comprise the metal in stoichiometric or excess quantity, 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, for example carbonate, hydroxide, oxalate, acetate, glutamate, preferably carbonate.

[0063] 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 additives relative to the total weight of the lubricating composition.

[0064] Also advantageously, the lubricating composition used according to the invention may also comprise a pour point lowering additive.

[0065] By slowing the formation of paraffin crystals, the pour point depressant additive generally improves the cold behavior of the lu- grinding machine according to the invention.

[0066] As examples of pour point lowering additives, mention may be made of alkyl polymethacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkyl-naphthalenes, alkyl polystyrenes.

[0067] Advantageously, the lubricating composition according to the invention may also comprise a dispersing agent.

[0068] The dispersing agents can be chosen from Mannich bases, succinimides and their derivatives.

[0069] Also advantageously, the lubricating composition used according to the invention may comprise from 0.2% to 10% by weight of dispersing agent relative to the total weight of lubricating composition.

[0070] The present invention also relates to the use as defined above, in which the reduction of particle emissions relates to the WLTC cycle or the RDE cycle, and more particularly the reduction of emissions of particles of a size greater than or equal to 10 nm, for example between 10 nm and 40 nm.

[0071] 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 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, less than or equal to 4.5 mm2 / s, and in which said lubricating composition has a viscosity at 150°C and under constant shear greater than or equal to 2.4 mPa.s *.

[0072] In this method, the particles, the base oil and the lubricating composition are as defined above.

[0073] The present invention covers all motorized vehicles, in particular vehicles comprising a 2-stroke or 4-stroke engine, gasoline, diesel, hybrid or gas engines.

[0074] The present invention covers all motorized vehicles, preferably comprising at least one combustion engine, in particular heavy vehicles or light vehicles.

[0075] The present invention will now be described with the aid of non-limiting examples. EXAMPLES Example 1: 1st test campaign Preparation of lubricating compositions

[0076] The lubricating compositions were prepared according to Tables 2 and 3 below.

[0077] [Tables2] Composition 1 (comparative) Composition 2 (comparative) Composition 3 (reference oil) Composition 4 (invention) Composition 5 (invention) Grade 0W12 0W20 0W20 0W20 0W20 Additive package 14 14 14 14 14 Base oil BOV4 Group III base oil Mixture of Group III base oils: 43% BOV 4 oil and 57% BOV 6 BOV 4 Group III base oil Mixture of 90% BOV 4 Group III base oil and 10% BOV 6 Group IV base oil Mixture of Group III base oils: 70% BOV 4 oil and 30% BOV 3 PISH polymer 0.4 0 4 4.4 5.6 PMA polymer 0 0 0 0 0

[0078] [Tables3] Composition 6 (invention) Composition 7 (invention) Composition 8 (invention) Composition 9 (invention) Grade 0W20 XW30 XW30 XW30 Additive package 14 14 14 14 Base oil BOV 3 Group III base oil BOV 3 Group III base oil BOV 4 Group III base oil BOV 4 Group III base oil PISH polymer 7 12.5 10.2 0 PAMA polymer 0 0 0 10.0

[0079] The figures in Tables 2 and 3 correspond to percentages by weight relative to the total weight of the composition.

[0080] The characteristics of the lubricating compositions are indicated in Tables 4 and 5 below:

[0081] [Tables4] Comp. 1 (comp.) Comp. 2 (comp.) Comp. 3 (reference oil) Comp. 4 (invention) Comp. 5 (invention) HTHS 150 (mPa.s ') CEC L-036-90 or ASTM D4683 2.17 2.55 2.64 2.6 2.6 Base oil viscosity (100°C) ASTM D445-97 (mm2 / s) 4.324 5.578 4.324 4.304 3n918 Noack volatility ASTM D5800 or CEC L-040-93 10.7 7.7 11.1 10.8 15.2

[0082] [Tables5] Comp. 6 (invention) Comp. 7 (invention) Comp. 8 (invention) HTHS 150 (mPa.s ') CEC L-036-90 or ASTM D4683 3.49 3.52 3.42 Base oil viscosity (100°C) ASTM D445-97 (mm 2 / s) 3.320 4.324 4.324 Noack volatility ASTM D5800 or CEC L-040-93 21 10.7 11.4 Measurement of the number of particles emitted

[0083] The compositions of Example 1 underwent the 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. An EB2ADTS (PSA Peugeot Citroën) engine with a displacement of 1.2 L (maximum power of 60 kW) was used.

[0084] The engine tests were carried out on turbocharged 3-cylinder in-line engines. The tests were 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 gases at the outlet of the turbocharger and upstream of the aftertreatment system.

[0085] The particle count 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 omitted 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.

[0086] This test campaign was therefore carried out on an iso-additivation matrix.

[0087] The results are shown in Tables 6 and 7 below, which relate to the WLTC and RDE cycles respectively.

[0088] The test of a reference oil (composition 3) frames each test. The test results are expressed relative to the result of the last reference oil passed. WLTC cycle Evolution of the number of particles (PN10) in comparison with composition 3 Composition 1 (comparative) +23% Composition 2 (comparative) +34% Composition 4 (invention) -8% Composition 5 (invention) -18% Composition 6 (invention) -46% Composition 7 (invention) -28% Composition 8 (invention) -26% RDE Cycle Evolution of the number of particles (PN10) in comparison with composition 3 Composition 1 (comparative) +5% Composition 2 (comparative) + 12% Composition 4 (invention) -11% Composition 5 (invention) -17% Composition 6 (invention) -24% Composition 7 (invention) -4% Composition 8 (invention) -22%

[0091] The results in Tables 6 and 7 demonstrate that the compositions used according to the invention effectively make it possible to reduce the number of particles of size greater than or equal to 10 nm, on the WLTC or RDE cycle.

[0092] Tables 8 and 9 below summarize the results obtained on the RDE or WLTC cycle for composition 3 with regard to particles of size 10 nm. These results show the repeatability of the effect of reducing the emission of PN10 particles. Tests 1 2 3 4 5 6 7 8 #PN10 per km travelled u on WLTC cycle 2.26.101 2 2.04.101 2 2.23.101 2 1.89.101 2 1.61.101 2 1.64.101 2 1.84.101 2 1.64.101 2 #PN10 per km travelled u on RDE cycle 4.88.101 2 4.34.101 2 4.32.101 2 4.17.101 2 3.57.101 2 3.52.101 2 3.75.101 2 3.63.101 2

[0094] [Tables9] Reference oil Composition 3 PN10 WLTC PN10 RDE Mean 1.88E12 3.97E12 Standard deviation 0.25E12 0.48E12 Standard deviation / mean 13% 12% Repeatability (95% CI) 0.69E12 1.34E12 Repeatability / mean 37% 34% Example 2: 2nd test campaign

[0095] A second test campaign was carried out. The lubricants differ in their viscosity grade but also in their composition of additives and base oils. Below, in Tables 10, 11 and 12, the characteristics of the lubricating compositions are shown, which demonstrate an influence of the viscosity grade on the reduction of the PN10 number, independently of the composition: Compo. 9 (Inv.) Compo. 10 (inv.) Compo. 11 (inv.) Composition. 4 (inv.) Compo. 12 (inv.) Grade 0W20 0W20 0W20 0W20 0W30 Additive package A (14%) A (14%) A (14%) A (14%) B (12%) Base oil BOV4 Group III base oil BOV 4 Group III base oil BOV 4 Group III base oil Mixture of 90% BOV 4 Group III base oil and 10% BOV 6 Group IV base oil Mixture of 40% BOV 4 Group III base oil, 40% BOV 4 Group IV base oil and 20% BOV 5 Group III base oil PISH polymer 4 4.4 4 4.4 3.2 PMA polymer 2.9 HTHS 150 (mPa.s ') CEC L-036-90 or ASTM D4683 2.63 2.61 2.64 2.6 3.03 Viscosity at 100°C ASTM D445-97 (mm2 / s) 8.379 8.247 8.228 8.291 9.840 Compo. 13 (inv.) Composition. 14 (inv.) Composition. 15 (inv.) Compo. 16 (comp.) Comp. 17 (comp.) Grade 0W30 5W30 5W40 0W12 0W12 Additive package C (13%%) D (15%) E(13.3%) F (13%) F (13%) Base oil Mixture of 70% BOV 4 Group III base oil, 10% BOV 4 Group IV base oil and 20% BOV 5 Group III base oil Mixture of 45% BOV 6 Group III base oil and 55% BOV 6 Group IV base oil Mixture of 55% BOV 4 Group III base oil and 45% BOV 8 Group IV base oil Mixture of 55% BOV 4 Group III base oil, 17% BOV 3 Group III base oil and 28% BOV 3 Group V Base Oil Mixture of 38% BOV 4 Group III Base Oil, 34% BOV 3 Group III Base Oil and 28% BOV 3 Group V Base Oil PISH Polymer 3.2 8.7 8.3 5 6 PMA Polymer 2.7 0 0 0 0 HTHS 150 (mPa.s ') CEC L-036-90 or ASTM D4683 3.01 3.50 3.78 2.11 2.11 Viscosity at 100°C ASTM D445-97 (mm2 / s) 9.890 11.28 14.54 5.978 5.967 . Compo. 18 (comp.) Compo. 19 (comp.) Grade 0W12 0W12 Additive package G (13.5%) G (13.5%) Base oil BOV 4 Group III base oil BOV 4 Group III base oil PISH polymer 0 0 PMA polymer 0 0 HTHS 150 (mPa.s ') CEC L-036-90 or ASTM D4683 1.92 2.00 Viscosity at 100°C ASTM D445-97 (mm2 / s) 5.457 5.868

[0099] Table 13 below shows the results obtained on the WLTC cycle for particles of size 10 nm. Quantity of particles per kilometer traveled with a size greater than or equal to 10 nm Composition 9 (invention) 2.84E+12 Composition 10 (invention) 2.49E+12 Composition 11 (invention) 2.39E+12 Composition 12 (invention) 2.25E+12 Composition 5 (invention) 1.25E+12 Composition 13 (invention) 1.14E+12 Composition 14 (invention) 1.75E+12 Composition 15 (invention) 5.00E+11 Composition 16 (comparative) 3.79E+12 Composition 17 (comparative) 4.35E+12 Composition 18 (comparative) 4.18E+12 Composition 19 (comparative) 4.01E+12

[0101] These results show that the use of a lubricating composition according to the invention makes it possible to reduce the quantity of particles having 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 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 mm2 / s, and wherein said lubricating composition has a viscosity at 150°C and under constant shear of greater than or equal to 2.4 mPa.s *.

2. Use according to claim 1, wherein the viscosity index of the base oil or mixture of base oils is greater than or equal to 130, preferably greater than or equal to 150.

3. Use according to claim 1 or 2, in which the particles have a size greater than or equal to 10 nm, preferably equal to 10 nm.

4. Use according to any one of claims 1 to 3, wherein the kinematic viscosity, measured at 100°C, of ​​the base oil or the mixture of base oils is from 1.5 to 4.5 mm2 / s, preferably from 3 to 4.5 mm2 / s, and preferentially from 4 to 4.5 mm2 / s.

5. Use according to any one of claims 1 to 4, wherein the viscosity at 150°C, and under constant shear, of the lubricating composition is from 2.4 mPa.s 1 to 5 mPa.s ', preferably from 2.6 mPa.s 1 to 5 mPa.s '.

6. Use according to any one of claims 1 to 5, wherein the lubricating composition 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 20 or 30.

7. Use according to any one of claims 1 to 6, wherein the amount of base oil or mixture of base oils is from 50% to 97% by weight relative to the total weight of the lubricating composition.

8. Use according to any one of claims 1 to 7, wherein the lubricating composition further comprises at least one viscosity index improving additive selected from the group consisting of hydrogenated butylene and styrene polymers, ethylene propylene copolymers and polymethacrylate polymers, said viscosity index improving additive preferably being a polymer of butylene and hydrogenated styrene.

9. Use according to any one of claims 1 to 8, wherein the reduction of particulate emissions relates to the WLTC cycle or the RDE cycle.