LUBRICATING COMPOSITION FOR 4-STROKE MARINE ENGINES

Abstract

LUBRICATING COMPOSITION FOR 4-STROKE MARINE ENGINE The present invention relates to a lubricating composition for 4-stroke marine engine, comprising: - one or more base oils, of which at least 5% to 95% by mass, relative to the total mass of said lubricating composition, of one or more base oils chosen from group II oils, group III oils and their mixtures; - from 0.3% to 3%, in particular from 0.5% to 2%, by mass of an olefin copolymer, relative to the total mass of said lubricating composition, and - from 2% to 30% by mass of detergent(s), relative to the total mass of said lubricating composition, said lubricating composition being free of copolymer of styrene and hydrogenated diene(s), and in which the kinematic viscosity at 100°C, measured according to standard ASTM D445, of the base oil or the mixture of base oils is strictly less than 7 mm2 / s. Figure for the abstract: none

Description

Title of the invention: COMPOSITION 4-STROKE MARINE ENGINE LUBRICANT

[0001] The present invention relates to the field of lubricating compositions, and more particularly to the field of lubricating compositions for four-stroke marine engines. More particularly, the present invention relates to a lubricating composition intended for use in a 4-stroke marine engine, this composition making it possible to reduce fuel consumption (Fuel Eco or FE). The present invention also relates to a method for reducing the fuel consumption, in particular fuel oil, of a ship using this lubricating composition.

[0002] In the automotive field, due to environmental concerns, there is an increasing desire to reduce pollutant emissions and achieve fuel savings. The nature of automotive engine lubricants has an influence on these two phenomena, and so-called "fuel-eco" (in English terminology) automotive engine lubricants have emerged. It is mainly the quality of the lubricating bases, alone or in combination with viscosity index improving polymers and / or friction modifying additives, which gives the lubricant its "fuel-eco" properties. The fuel savings generated by "fuel-eco" engine lubricants are essentially achieved during cold start-up, when the engine is not yet in stabilized mode, and not at high temperature in stabilized mode.In general, consumption gains in the NEDC cycle (New European Driving Cycle) according to European directive 70 / 220 / EEC are 5% cold (urban cycle), 1.5% hot (extra-urban cycle), for average gains of 2.5%.

[0003] However, in the field of marine lubricants, marine engines operate at a stabilized speed, there are few cold starts. The "fuel-eco" solutions adapted to automobile engines are therefore not suitable for marine engines. In particular, the consumption gains obtained in the automobile field cannot be obtained in the marine field.

[0004] Furthermore, the formulation of a “fuel-eco” lubricant must not be to the detriment of the other performances of the lubricant. In particular, wear resistance, demulsification, neutralization capacity and control of the formation of varnishes and deposits (piston engine and / or crankcase cleanliness) must not be impaired.

[0005] There is therefore an interest in having a lubricating composition for a marine engine which allows satisfactory reductions in fuel consumption, particularly fuel oil, while maintaining the other performances of the lubricating composition.

[0006] An objective of the present invention is therefore to provide a lubricating composition which overcomes all or part of the aforementioned drawbacks. In particular, an objective of the present invention is to provide a lubricating composition suitable for 4-stroke marine engines allowing fuel savings, in particular Fuel Eco (FE) savings, while maintaining the other performances of the lubricating composition.

[0007] Another objective of the present invention is to provide a lubrication method allowing fuel savings, in particular fuel oil, while maintaining the other performances of the lubricating composition.

[0008] Still other objectives will appear on reading the description of the invention which follows.

[0009] To this end, the invention relates to a lubricating composition for a 4-stroke marine engine, comprising:

[0010] - one or more base oils, of which at least 5% to 95% by mass, relative to to the total mass of said lubricating composition, of one or more base oils chosen from group II oils, group III oils and their mixtures;

[0011] - from 0.3% to 3% by mass of an olefin copolymer, relative to the total mass of said lubricating composition, and

[0012] - from 2% to 30% by mass of detergent(s), relative to the total mass of said lubricating composition,

[0013] said lubricating composition being free of copolymer of styrene and hydrogenated diene(s), and

[0014] wherein the kinematic viscosity at 100°C, measured according to ASTM D445, of the base oil or base oil mixture is strictly less than 7 mm2 / s.

[0015] Surprisingly, the applicant has found that it is possible to formulate lubricating compositions for 4-stroke marine engines which make it possible to significantly reduce fuel consumption, in particular fuel oil (Fuel Eco), while maintaining the other performances of the lubricating composition, compared to conventional lubricating compositions for marine engines. This is made possible by a lubricating composition having the aforementioned characteristics.

[0016] Thus, the present invention makes it possible to formulate lubricating compositions for 4-stroke marine engines which make it possible to combine both fuel savings, in particular fuel (Fuel Eco) and maintenance of the other performances of the lubricating compositions.

[0017] In particular, a lubricating composition according to the invention exhibits good stability to thermo-oxidative aging during its use over time.

[0018] The present invention also relates to a lubricating composition as defined above, in which the olefin copolymer is an ethylene-propylene copolymer.

[0019] The present invention also relates to a composition as defined above, having a kinematic viscosity at 100°C, measured according to the ASTM D445 standard, of less than 16.3 mm2 / s, preferably between 9.3 and 16.3 mm2 / s, and preferentially between 12.5 and 16.3 mm2 / s.

[0020] The present invention also relates to the use of a lubricating composition as defined above for the lubrication of 4-stroke marine engines and / or for reducing the fuel consumption of the engine.

[0021] The present invention also relates to a method of lubricating a 4-stroke marine engine, comprising bringing at least one mechanical part of the 4-stroke marine engine into contact with a lubricating composition as defined above.

[0022] The present invention also relates to a method for reducing the fuel consumption of a 4-stroke marine engine comprising contacting at least one mechanical part of the 4-stroke marine engine with a lubricating composition as defined above.

[0023] Other characteristics and variants of the lubricating composition according to the invention will become more apparent on reading the description and examples which follow, given by way of illustration and not limitation of the invention.

[0024] In the rest of the text, the expressions “between ... and ...”, “from ... to ...”, “ranging ... to ...” and “varying from ... to ...” are equivalent and are intended to mean that the limits are included, unless otherwise stated.

[0025] As indicated above, the present invention relates to a lubricating composition (or a lubricant) for a 4-stroke marine engine, comprising:

[0026] - one or more base oils, of which at least 5% to 95%, preferably 60% at 90%, preferably from 70% to 85%, by mass, relative to the total mass of said lubricating composition, of one or more base oils, chosen from group II oils, group III oils and their mixtures;

[0027] - from 0.3% to 3%, in particular from 0.5% to 2%, by mass of an olefin copolymer, by relative to the total mass of said lubricating composition, and

[0028] - from 2% to 30% by mass of detergent(s), relative to the total mass of said lubricating composition,

[0029] said lubricating composition being free of copolymer of styrene and hydrogenated diene(s), and

[0030] wherein the kinematic viscosity at 100°C, measured according to ASTM D445, of the base oil or base oil mixture is strictly less than 7 mm2 / s.

[0031] A lubricating composition according to the invention is therefore suitable for four-stroke marine engines.

[0032] A lubricating composition according to the invention is free of copolymer of styrene and hydrogenated diene(s), and therefore in particular free of copolymer of styrene and hydrogenated isoprene and copolymer of styrene and hydrogenated butadiene.

[0033] In particular, a lubricating composition according to the invention does not comprise a copolymer of styrene, hydrogenated butadiene and hydrogenated isoprene.

[0034] According to one embodiment, the lubricating composition according to the invention has a kinematic viscosity at 100°C, measured according to the ASTM D445 standard, of less than 16.3 mm2 / s, in particular between 6.9 mm2 / s and 16.3 mm2 / s, preferably between 9.3 mm2 / s and 16.3 mm2 / s, and preferentially between 12.5 mm2 / s and 16.3 mm2 / s.

[0035] In one embodiment of the invention, the lubricating compositions according to the invention have a viscometric grade ranging from SAE 20 to SAE 40 according to the SAEJ300 classification. In particular, a lubricating composition according to the invention may have a viscometric grade SAE 20, SAE 30 or SAE 40 according to the SAEJ300 classification, preferably SAE 30 or SAE 40, advantageously SAE 40.

[0036] Grade 20 (or SAE 20) oils have a kinematic viscosity at 100°C of between 6.9 and 9.3 mm2 / s. Grade 30 (or SAE 30) oils have a kinematic viscosity at 100°C of between 9.3 and 12.5 mm2 / s. Grade 40 (or SAE 40) oils have a kinematic viscosity at 100°C of between 12.5 and 16.3 mm2 / s.

[0037] Kinematic viscosity is measured according to ASTM D445 at 100°C. Base oil(s)

[0038] A lubricating composition according to the invention comprises a base oil or a mixture of base oils including at least one or more oils chosen from group II oils, group III oils and mixtures thereof.

[0039] A lubricating composition according to the invention therefore comprises at least one group II base oil and / or at least one group III oil.

[0040] In other words, a lubricating composition according to the invention comprises one or more group II oils, or one or more group III oils or even a mixture of group II and group III oils.

[0041] A lubricating composition according to the invention comprises from 5% to 95% by mass of one or more group II and / or III base oils, relative to the total mass of said lubricating composition.

[0042] Preferably, a lubricating composition according to the invention comprises from 30% to 90%, in particular from 50% to 90%, in particular from 60% to 90%, preferentially from 65% to 85%, and more preferably from 70% to 85%, by mass relative to the total mass of said lubricating composition of one or more base oils chosen from group II oils, group III oils and their mixtures.

[0043] According to one embodiment, a lubricating composition according to the invention comprises at least one group II oil, in particular in a mass content greater than or equal to 65%.

[0044] In a particular embodiment, a lubricating composition according to the invention comprises one or more group II oil(s) alone (in other words, does not comprise group III oil), in particular in a mass content greater than or equal to 60% by mass, in particular greater than or equal to 65%, relative to the total mass of said lubricating composition. In a particular embodiment, the mass content of group II oil(s), in particular in the case where the lubricating composition does not comprise group III oil, may be greater than or equal to 70% by mass, in particular greater than or equal to 75% by mass.

[0045] According to one embodiment, a lubricating composition according to the invention comprises at least one group III oil.

[0046] In another particular embodiment, a lubricating composition according to the invention comprises one or more group III oil(s) alone (in other words, does not comprise group II oil), in particular in a mass content greater than or equal to 60%, or even greater than or equal to 65%, or even greater than or equal to 70%, or even greater than or equal to 75%, relative to the total mass of said lubricating composition.

[0047] A lubricating composition may comprise, in addition to said group II base oil(s) and / or said group III oil(s), one or more additional base oil(s), in other words one or more base oils distinct from the group II and III oils.

[0048] According to one embodiment, a lubricating composition according to the invention may thus comprise one or more additional base oils chosen from group I base oils, group IV base oils and group V base oils, said additional base oil preferably being a group I base oil.

[0049] According to one embodiment, a lubricating composition according to the invention comprises at least one additional base oil chosen from group I base oils.

[0050] In this embodiment, a lubricating composition according to the invention thus comprises one or more group II and / or group III base oil(s), in combination with a group I base oil.

[0051] For example, a lubricating composition according to the invention may comprise at least one group II base oil, in combination with at least one group I base oil.

[0052] Preferably, the mass content of additional base oil(s), when present, in particular group I oil(s), is from 0.5% to 90%, in particular from 1% to 50%, in particular from 1.5% to 30%, and preferably from 2% to 15%, relative to the total mass of said lubricating composition.

[0053] The above-mentioned base oils may be chosen from base oils conventionally used in the field of lubricating oils, such as mineral, synthetic or natural, animal or vegetable oils or mixtures thereof.

[0054] It may be a mixture of several base oils, for example a mixture of two, three or four base oils.

[0055] The base oils used in the lubricating compositions according to the invention may in particular be oils of mineral or synthetic origin belonging to groups I to V according to the classes defined in the API classification, or their equivalents according to the ATIEL classification (table 1), or their mixtures.

[0056] [Tables 1] Saturates content Sulphur content Viscosity index (VI) Group I Mineral oils <90% > 0.03% 80 <VI < 120 Groupe II Huiles hydrocraquées >90% <0.03% 80 <VI < 120 Groupe III Huiles hydrocraquées ou hydro-isomérisées >90% <0.03% >120 Group IV Polyalphaolefins (PAO) Group V Esters and other bases not included in groups I to IV

[0057] Mineral base oils include all types of base oils obtained by atmospheric and vacuum distillation of crude oil, followed by operations of refining such as solvent extraction, desalting, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing.

[0058] Group I mineral bases are for example the bases called Neutral Solvent (such as for example, 150NS, 330NS, 500NS or 600NS) or Brightstock.

[0059] Synthetic base oils may be esters of carboxylic acids and alcohols, polyalphaolefins or polyalkylene glycols (PAG) obtained by polymerization or copolymerization of alkylene oxides comprising from 2 to 8 carbon atoms, in particular from 2 to 4 carbon atoms. The polyalphaolefins used as base oils are for example obtained from monomers comprising 4 to 32 carbon atoms, for example from decene, octene or dodecene, and whose viscosity at 100°C is between 1.5 and 15 mm2.s 1 according to the ASTM D445 standard. Their average molecular mass is generally between 250 and 3000 g / mol according to the ASTM D5296 standard.

[0060] Mixtures of synthetic and mineral oils, which can be bio-sourced, can also be used.

[0061] The base oil or all of the base oils present in the lubricating composition according to the invention, including said group II and / or group III base oil(s), and optionally one or more additional oils, for example one or more group I oils, may represent from 50% to 97%, in particular from 55% to 95% by mass, in particular from 60% to 90% by mass, relative to the total mass of the composition.

[0062] A lubricating composition according to the invention can be characterized by its BOV (for “Base Oil Viscosity” in English) which is an indication of the viscosity of the base oil or of the mixture of all the base oils of the lubricating composition.

[0063] Thus, the base oil or the mixture of all the base oils of the lubricating composition according to the invention has a kinematic viscosity at 100°C, measured according to the ASTM D445 standard, strictly less than 7 mm2 / s.

[0064] According to one embodiment, the BOV of a lubricating composition according to the invention is less than or equal to 6.5 mm2 / s. Olefin copolymer

[0065] A lubricating composition according to the invention comprises at least one olefin copolymer.

[0066] These olefin copolymers may be copolymers based on ethylene units and propylene units, or copolymers based on ethylene units, propylene units and diene units (EPDM). Preferably, the olefin copolymer used according to the invention is an ethylene / propylene copolymer.

[0067] The olefin copolymer used according to the invention is in linear or star form, preferably in linear form. The olefin copolymer used according to the invention is in block form or in random form. Preferably, the olefin copolymer is in random form.

[0068] The olefin copolymer used according to the invention advantageously has a content of ethylene units, ranging from 30% to 80% by mass, relative to the mass of the olefin copolymer, preferably from 30% to 70%, more preferably from 40% to 70%.

[0069] The olefin copolymer used according to the invention advantageously has a content of propylene units, ranging from 20% to 70% by mass, relative to the mass of the olefin copolymer, preferably from 30% to 70%, more preferably from 30% to 60%.

[0070] The amount of olefin copolymer in a lubricating composition according to the invention is from 0.3% to 3% by mass, preferably from 0.5% to 2% by mass relative to the total mass of the lubricating composition. This amount is understood as the amount of dry matter of polymer. Indeed, the olefin copolymer used in the context of the present invention is sometimes found diluted in a mineral or synthetic oil (most often a group I, II or III oil according to the API classification). Additives

[0071] A lubricating composition according to the invention may comprise all types of additives usually used in marine lubricants.

[0072] It is understood that the nature of the other additives used is chosen so as not to negatively impact the properties sought for the marine lubricant.

[0073] These additives can be introduced in isolation and / or in the form of a mixture, or "additive package", similar to those already available for sale for commercial lubricant formulations for marine engines.

[0074] These additives may in particular be chosen from detergent additives, basic organic additives improving the total base number (TBN), anti-wear additives, extreme pressure additives, dispersant additives, anti-foaming agents, antioxidant additives, anti-rust additives, friction modifiers, and mixtures thereof. Detergent(s)

[0075] A lubricating composition according to the invention comprises one or more detergents.

[0076] The mass content of detergent(s) is between 2% and 30% relative to the total mass of the lubricating composition.

[0077] The detergents used in the lubricating compositions according to the present invention may be chosen from detergents known to those skilled in the art.

[0078] Detergents commonly used in the formulation of lubricating compositions are typically anionic compounds comprising a long lipophilic hydrocarbon chain and a hydrophilic head. The associated cation is typically a metal cation of an alkali or alkaline earth metal.

[0079] The detergents may be chosen from alkali or alkaline earth metal salts of carboxylates, sulfonates, salicylates, naphthenates, and phenates taken alone or in mixture. The detergents are named according to the nature of the hydrophobic chain, carboxylate, sulfonate, salicylate, naphthenate or phenate.

[0080] The alkali and alkaline earth metals are preferably calcium, magnesium, sodium or barium, more preferably calcium.

[0081] The detergents used will be non-overbased (or neutral) or overbased. We speak of non-overbased or "neutral" detergents when the metal salts contain the metal in an approximately stoichiometric quantity. We speak of overbased detergents when the metal is in excess (in an amount greater than the stoichiometric quantity). The excess metal providing the overbased character to the detergent is in the form of oil-insoluble metal salts. Overbased detergents are thus in the form of micelles composed of insoluble metal salts held in suspension in the lubricating composition by the detergents in the form of oil-soluble metal salts. These micelles may contain one or more types of insoluble metal salts, stabilized by one or more types of detergents.Overbased detergents will be said to be of mixed type if the micelles include several types of detergents, differing from each other by the nature of their hydrophobic chain.

[0082] Preferred detergents are carboxylates, sulfonates and / or phenates, taken alone or in mixture, in particular calcium carboxylates, sulfonates and / or phenates.

[0083] According to one embodiment, the quantity of detergents in the lubricating composition according to the invention is from 2% to 25% by mass, relative to the total mass of the lubricating composition, preferably from 2% to 20%.

[0084] The BN (Base Number measured according to ASTM D2896) of the lubricating compositions according to the present invention is totally or partly provided by neutral or overbased detergents based on alkali or alkaline earth metals.

[0085] The BN value of the lubricating compositions according to the present invention, measured according to ASTM D2896, can vary from 1 to 140 mg of KOH / g, preferably from 3 to 80 mg of KOH / g, more preferably from 4 to 60 mg of KOH / g. The BN value will be chosen according to the conditions of use of the lubricating compositions and in particular according to the sulfur content of the fuel oil used.

[0086] Thus for fuel oils with a high sulfur content (of the order of 0.2% to 4.5% by weight), the BN value of the composition will be between 20 and 80 mg of KOH / g, more preferably between 30 and 65 mg of KOH / g.

[0087] For fuel oils with a low sulfur content (of the order of 0.05% to 0.2% by weight), the BN value of the composition will be between 5 and 20 mg of KOH / g, more preferably between 10 and 15 mg of KOH / g.

[0088] A lubricating composition according to the invention may further comprise one or more additives other than detergents.

[0089] According to one embodiment, a lubricating composition according to the invention comprises an anti-wear additive and / or an extreme pressure additive.

[0090] Anti-wear additives and extreme pressure additives protect friction surfaces by forming a protective film adsorbed on these surfaces.

[0091] There is a wide variety of anti-wear additives. Examples include phospho-sulfur additives, such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates (or ZnDTP). The alkyl groups of these zinc dialkyldithiophosphates preferably contain from 1 to 18 carbon atoms. The preferred compounds are of formula Zn((SP(S)(OR)(OR'))2, in which R and R', which may be identical or different, independently represent an alkyl group, preferably an alkyl group comprising from 1 to 18 carbon atoms.

[0092] Preferably, a lubricating composition according to the invention may comprise ZnDTP.

[0093] Amine phosphates, polysulfides, in particular sulfur-containing olefins, are also anti-wear additives which can be used in a lubricating composition according to the invention. Mention may also be made of nitrogen-containing and sulfur-containing anti-wear additives, such as, for example, metal dithiocarbamates, in particular molybdenum dithiocarbamates.

[0094] Advantageously, the extreme pressure and / or anti-wear additive(s) may be present in a lubricating composition according to the invention in a content ranging 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 total mass of lubricating composition.

[0095] A lubricating composition considered according to the invention may also comprise at least one basic organic additive making it possible to increase the total base number, known as TBN, of the lubricating composition.

[0096] These basic organic additives, called “TBN boosters”, make it possible to increase the total base number of the composition; in other words, they are capable of neutralizing acids and provide improved detergent performance.

[0097] Basic organic additives improving TBN are known to those skilled in the art.

[0098] They may in particular be organic amino, alkyl or aromatic additives or even nitrogenous dispersants.

[0099] As basic organic additives improving TBN, fatty amines may be mentioned, for example.

[0100] In particular, said basic organic additive(s) improving the TBN may be used in a content greater than or equal to 0.1% by mass, relative to the total mass of said lubricating composition, in particular in a content of between 0.1% and 10% by mass, more particularly between 0.5% and 7% by mass, preferably between 1% and 5% by mass.

[0101] A lubricating composition according to the invention may also comprise at least one anti-foam additive, in particular used to counter the effect of metallic detergents. The anti-foam additives may be chosen from polar polymers such as polymethylsiloxanes or polyacrylates.

[0102] In particular, a lubricating composition according to the invention may comprise from 0.01% to 3% by mass of anti-foam additive(s), relative to the total mass of the lubricating composition.

[0103] A lubricating composition according to the invention may comprise at least one antioxidant additive. The antioxidant additives are essentially dedicated to delaying the degradation of the lubricating composition in service. This degradation may in particular result in the formation of deposits or in an increase in the viscosity of the lubricating composition. They act in particular as radical inhibitors or hydroperoxide destroyers.

[0104] Among the commonly used antioxidant additives, mention may be made of phenolic type antioxidant additives, amine type antioxidant additives, phosphosulfur antioxidant additives. The phenolic antioxidant additives may be in the form of neutral or basic metal salts. The antioxidant additives may in particular be chosen from sterically hindered phenols, sterically hindered phenol esters and sterically hindered phenols comprising a thioether bridge, diphenylamines, diphenylamines substituted by at least one C1-C12 alkyl group, N,N'-dialkyl-aryl-diamines and mixtures thereof.

[0105] Preferably, the sterically hindered phenols are chosen from compounds comprising a phenol group in which at least one vicinal carbon of the carbon carrying the alcohol function is substituted by at least one C1-C10 alkyl group, preferably a C1-C6 alkyl group, preferably a C4 alkyl group, preferably by the tert-butyl group.

[0106] Amino 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 N(R5)(R6)(R7) in which R5 represents an aliphatic group or an aromatic group, optionally substituted, R6 represents an aromatic group, optionally substituted, R7 represents a hydrogen atom, an alkyl group, an aryl group or a group of formula R8S(O)ZR9 in which R8 represents an alkylene group or an alkenylene group, R9 represents an alkyl group, an alkenyl group or an aryl group and z represents 0, 1 or 2.

[0107] Sulphurized alkyl phenols or their alkali and alkaline earth metal salts can also be used as antioxidant additives.

[0108] A lubricating composition according to the invention may contain all types of antioxidant additives known to those skilled in the art.

[0109] Advantageously, the antioxidant additive(s) may be present in a lubricating composition according to the invention in a content ranging from 0.01% to 10% by mass, preferably from 0.05% to 8% by mass, more preferably from 0.1% to 5% by mass, even more preferably from 0.1% to 2% by mass relative to the total mass of lubricating composition.

[0110] In one embodiment, the lubricating composition according to the invention may further comprise at least one dispersing agent.

[0111] The dispersing agents ensure the maintenance in suspension and the evacuation of insoluble solid contaminants constituted by the secondary oxidation products which are formed when the lubricating composition is in service or by combustion residues, unburned matter, or any other contaminant. They can be chosen from Mannich bases, succinimides and their derivatives, in particular from polyisobutylene succinimide (PIBSI) or polyisobutylene succinic anhydride (PIBSA).

[0112] In particular, a lubricating composition considered according to the invention may comprise from 0.2% to 10% by mass of dispersing agent(s), relative to the total mass of the composition.

[0113] A lubricating composition according to the invention may also comprise friction modifiers. Friction modifiers make it possible to reduce friction between engine parts as much as possible. These additives help to prevent engine damage, while increasing fuel economy. They can be chosen from organic molecules having a polar function at one end: carboxylic acid and derivatives, glycerol ester, imides, fatty amides, fatty amines and derivatives, phosphoric or phosphonic acid derivatives. (phosphite or amine phosphate). They act by chemical reaction on the metal surface or by absorption on the metal surface (hydrogen bonding).

[0114] Another type of friction modifier can be selected from organometallic compounds: molybdenum dithiophosphate, molybdenum dithiocarbamate, copper oleate, copper salicylate.

[0115] Finally, the friction modifier can be a solid compound, the most common being molybdenum disulfide MoS2, boron nitride, polytetrafluoroethylene (PTFE).

[0116] The mass content of friction modifier in a lubricating composition according to the invention may range from 0.01% to 5% by mass, preferably from 0.02% to 4%, more preferably from 0.02% to 2% by mass, relative to the total mass of the lubricating composition.

[0117] According to one embodiment, a composition of the invention does not comprise a glycerol ester.

[0118] According to one embodiment, a composition of the invention does not comprise a polyol ester(s).

[0119] A lubricating composition according to the invention is advantageously used in 4-stroke marine engines.

[0120] In a preferred embodiment, a lubricating composition is used in high-speed or semi-high-speed 4-stroke engines, which operate respectively with distillates and bunker or heavy fuel oil and also with gas.

[0121] In particular, a lubricating composition according to the invention is suitable for 4-stroke engines as a barrel piston engine oil also called TPEO oil.

[0122] Thus, the invention also relates to a trunk piston engine oil also called TPEO oil (Trunk Piston Engine Oil in English) comprising a lubricating composition as defined above.

[0123] By piston oil for barrel piston engine also called TPEO oil according to the invention, is meant any lubricating composition intended for the lubrication of 4-stroke marine engines, in particular the crankcase and the cylinders.

[0124] In particular, a lubricating composition according to the invention is distinct from an oil for 2-stroke marine engines, in particular from a system oil for 2-stroke marine engines.

[0125] The invention also relates to the use of a lubricating composition as defined above for the lubrication of 4-stroke marine engines.

[0126] The invention also relates to the use of a lubricating composition as defined above, to reduce the consumption of fuel, in particular fuel oil, of the engine.

[0127] The expression "reduce fuel consumption" refers to a reduction in fuel consumption compared to the fuel consumption associated with a conventional lubricating composition, particularly without olefin copolymer.

[0128] The reduction in fuel consumption, particularly fuel oil, is notably evaluated by engine bench tests.

[0129] All of the characteristics and preferences presented for the lubricating composition apply to the above use.

[0130] The present invention also relates to a method of lubricating a 4-stroke marine engine, comprising bringing at least one mechanical part of the 4-stroke marine engine into contact with a lubricating composition as defined above.

[0131] The present invention also relates to a method for reducing the consumption of fuel, in particular fuel oil, of a 4-stroke marine engine comprising bringing at least one mechanical part of the 4-stroke marine engine into contact with a lubricating composition as defined above.

[0132] All of the characteristics and preferences presented for the lubricating composition also apply to the processes / methods according to the invention.

[0133] The various objects of the present invention and their implementations will be better understood by reading the examples which follow. These examples are given for information purposes only, without limitation. EXAMPLES

[0134] Example 1: Formulation of a lubricating composition according to the invention Preparation of the compositions

[0135] Two lubricating compositions, CCI and CL1, were prepared by simple mixing, at temperatures between 60 and 70°C, of ​​the following components, in the mass proportions indicated in Table 2.

[0136] [Tables2] Compounds CL1 (invention) CCI (comparative) Additive package 1 (1) 10.1 Additive package 2 (1) 22.9 Olefin copolymer (2) (5% active matter in a group I base oil) 16.3 5.0 Styrene / diene(s) copolymer (3) 6.9 (8% active matter in a group I base oil) Group II oil(4) 73.6 Group II oil(5) 64.7 Additive Friction modifier (6) 0.5

[0137] (1) Additive packages including in particular detergents in a content greater than 90% by mass, anti-wear additives, in particular phospho-sulfur, and anti-foam;

[0138] (2) Olefin copolymer: 58% by mass ethylene and 42% by mass propylene,

[0139] (3) Hydrogenated and linear styrene / butadiene copolymer having the proportions following mass: 71% hydrogenated butadiene mass and 29% styrene mass,

[0140] (4) Group II base oil, having a viscosity measured at 100°C according to ASTM D445 (KV100) standard of 4.4 mm2 / s and a Noack volatility, determined according to CEC L-040-093 standard, of 15.2% by mass,

[0141] (5) Mixture of group II base oils, respectively having a viscosity measured at 100°C according to ASTM D445 (KV100) of 4.1 mm2 / s and 6.4 mm2 / s and a Noack volatility, determined according to CEC L-040-093, of 15.2% and 9.0% by mass,

[0142] (6) Dithiocarbamate type inorganic friction modifier additive molybdenum.

[0143] Measurement of the rheological properties of lubricating compositions

[0144] The kinematic viscosity at 100°C (KV100) of the composition prepared above and CCI was measured according to ASTM D445.

[0145] The BOV or "Base Oil Viscosity" in English, corresponds to the viscosity KV100 of the base oil or mixture of base oils. In the case of a mixture of base oils, the KV100 of the mixture of base oils is calculated according to the following equation (Arrhenius rule), for a mixture of 2 base oils:

[0146] log (visco mixture) = Xi*log(viscol) +x2*log(visco2), with

[0147] visco mixture the viscosity of the mixture of oils 1 and 2,

[0148] viscol the viscosity of base oil 1, visco2 the viscosity of base oil 2,

[0149] Xi and x2 the respective molar fractions of base oil 1 and base oil 2 (x1+x2=l),

[0150] the same equation can be implemented and extrapolated for a mixture of n base oils.

[0151] The results are collected in the following table 3.

[0152] [Tables3] Characteristics CL1 CCI Lubricant grade according to SAEJ300 SAE 40 SAE 30 KV100 in mm2 / s (measured at 100°C according to A STM D445) 13.29 10.88 KV40 in mm2 / s (measured at 40°C according to AS TM D445) 77.97 65.08 Viscosity index (VI) (calculated according to standard I SO2908) 174 159 BOV in mm2 / s (measured at 100°C according to A STM D445) 5.3 4.6

[0153] Example 2: Evaluation of fuel consumption saving properties

[0154] The fuel-saving properties of the lubricating composition according to the invention were validated by a test carried out on a bench equipped with a MAN 5L16 / 24 engine. The particular characteristics of this engine were described in the publication entitled "INNOVATOR-4C, The cutting-edge MAN B&W 5L16 / 24 test engine", by D. Lançon, V. Doyen and J. Christensen, CIMAC Congress 2004, KYOTO (Paper 124).

[0155] A dedicated steady-state procedure has been developed to measure the “fuel eco” properties of lubricating compositions as described below. This procedure uses equipment normally found in engine bench test centers: • Flushing the engine and lubrication circuits with the candidate lubricant, • Running in the engine with the candidate lubricant, • Measurement of distillate fuel oil consumption (Marine Diesel Oil - according to ISO8217 specification). Measurements are repeated to ensure accuracy, • The fuel oil consumption obtained with the candidate lubricant is compared with that obtained when a reference lubricant is tested under the same conditions, • The engine operating conditions are: • Speed: 1000 rpm, • Power developed 450kW: 100% load, i.e. 450kW and 75% load, i.e. 337kW, loads representative of marine engine operation, • Lubricant temperature at the engine inlet: 68-70°C, • Lubricant volume: 2 x 200 liters, • The tests are organized according to a precise protocol which consists of supervising any test carried out with a candidate lubricant between two tests carried out with the reference lubricant. This makes it possible to guarantee the stability of engine operation as well as the statistically significant nature of the consumption differences measured between lubricants, • In this case, the reference lubricant is a commercial oil for semi-fast 4T engines with a viscosity grade of SAE 40 and BN 30.

[0156] The comparative composition CCI and the composition according to the invention CL1 were evaluated.

[0157] The results, representing the gain in fuel consumption compared to the comparative composition, at the engine loads tested, are grouped in Table 4.

[0158] [Tables4] Fuel consumption gain (%) CL1 (invention) At 100% engine load +0.9 At 75% engine load +0.9

[0159] It is noted that the use of an olefin copolymer according to the invention makes it possible, in the lubricating composition CL1, to reduce by more than 0.8%, or even at least 0.9%, the fuel oil consumption (at 75% as at 100% engine load) compared to the composition CCI (comparative). This result is all the more surprising since the lubricating composition CL1 according to the invention is of SAE 40 grade, while the comparative composition CCI is of SAE 30 grade.

[0160] In fact, it is known to those skilled in the art that the FE performances are partly linked to the grade of the lubricant: typically, it is known that a lubricant of SAE 30 grade is more efficient in fuel oil savings than a lubricant of SAE 40 grade. However, it is noted here, surprisingly, that the CL1 composition is more efficient than the CCI composition, while it has an SAE 40 grade and the CCI composition (comparative) is of SAE 30 grade.

[0161] Thus, the examples above show that the lubricating compositions according to the invention significantly reduce fuel consumption, particularly fuel oil.

Claims

Claims

1. Lubricating composition for a 4-stroke marine engine, comprising: - one or more base oils, of which at least 5% to 95% by mass, relative to the total mass of said lubricating composition, of one or more base oils chosen from group II oils, group III oils and their mixtures; - from 0.3% to 3%, in particular from 0.5% to 2%, by mass of an olefin copolymer, relative to the total mass of said lubricating composition, and - from 2% to 30% by mass of detergent(s), relative to the total mass of said lubricating composition, said lubricating composition being free of copolymer of styrene and hydrogenated diene(s), and in which the kinematic viscosity at 100°C, measured according to standard ASTM D445, of the base oil or the mixture of base oils is strictly less than 7 mm2 / s.

2. A lubricating composition according to claim 1, not comprising a glycerol ester.

3. A lubricating composition according to claim 1 or 2, not comprising a copolymer of styrene, hydrogenated butadiene and hydrogenated isoprene.

4. A lubricating composition according to any one of claims 1 to 3, wherein the olefin copolymer is an ethylene-propylene copolymer.

5. Lubricating composition according to claim 4, in which the ethylene-propylene copolymer comprises a content of ethylene units ranging from 30% to 80% by mass relative to the mass of the olefin copolymer, preferably from 30% to 70%, more preferably from 40% to 70%.

6. Lubricating composition according to any one of claims 1 to 5, having a kinematic viscosity at 100°C, measured according to standard ASTM D445, of less than 16.3 mm2 / s, preferably between 9.3 and 16.3 mm2 / s, and preferentially between 12.5 and 16.3 mm2 / s.

7. A lubricating composition according to any one of claims 1 to 6, comprising one or more additional base oils selected from Group I base oils, Group I base oils, Group I base oils, and Group I base oils. group IV and group V base oils, said additional base oil preferably being a group I base oil.

8. A lubricating composition according to any one of claims 1 to 7, wherein the amount of detergents is from 2% to 25%, preferably from 2% to 20%, by mass relative to the total mass of said lubricating composition.

9. A lubricating composition according to any one of claims 1 to 8, further comprising one or more additives selected from basic organic additives improving the total base number, anti-wear additives, extreme pressure additives, dispersant additives, anti-foaming agents, antioxidant additives, anti-rust additives, friction modifiers, and mixtures thereof.

10. Use of a lubricating composition according to any one of claims 1 to 9, for the lubrication of a 4-stroke marine engine.

11. Use of a lubricating composition according to any one of claims 1 to 9, for reducing the fuel consumption of a 4-stroke marine engine.

12. A method of lubricating a 4-stroke marine engine, comprising contacting at least one mechanical part of the 4-stroke marine engine with a lubricating composition according to any one of claims 1 to 9.

13. A method of reducing the fuel consumption of a 4-stroke marine engine comprising contacting at least one mechanical part of the 4-stroke marine engine with a lubricating composition according to any one of claims 1 to 9.