USE OF ESTERS TO IMPROVE THE CLEANLINESS OF MARINE ENGINES

Abstract

USE OF ESTERS FOR IMPROVING THE CLEANLINESS OF MARINE ENGINES The present invention relates to the use of at least one polyol ester(s) having a viscosity at 100°C, measured according to ASTM D445, strictly less than 200 cSt, in a lubricant composition for a marine engine, to improve the cleanliness of said marine engine. Figure for the abstract: none

Description

Title of the invention: USE OF ESTERS FOR IMPROVING THE CLEANLINESS OF MARINE ENGINES

[0001] The present invention relates to the field of lubricating compositions, more particularly to the field of lubricating compositions for marine engines, especially four-stroke marine engines. The present invention more specifically relates to the use of specific esters in a lubricating composition to improve engine cleanliness, particularly that of marine engines.

[0002] In the maritime field, significant efforts are concentrated on lubricating compositions in order to neutralize the sulfuric acid formed during the combustion of fuel oil, which makes it possible to significantly reduce the corrosive wear of engine parts.

[0003] To address the issue of reducing corrosive wear, numerous additives are used in lubricating compositions, but these can have detrimental effects on the cleanliness of engine parts, particularly the crankcase. Indeed, when these additives come into contact with sulfuric acid and / or are subjected to the temperature and pressure stresses applied within the engine, they can partially or completely decompose and form deposits that foul these parts. As a result, the deposits formed lead to increased wear and rapid fouling of engine parts, and consequently, a more rapid reduction in engine lifespan.

[0004] Furthermore, the temperatures reached in the combustion chamber and adjacent components of four-stroke marine engines promote the formation of deposits. These deposits consist of combustion products and / or degradation products of the fuel and lubricant used. This phenomenon is exacerbated when using engine lubricants containing a viscosity-modifying polymer (or a mixture of such polymers). These deposits impair the proper functioning of the engine.

[0005] To date, detergent additives, such as sulfonates, phenates, or salicylates, are used to reduce these deposits. However, this solution has the drawback of generating ash formed from metallic salts during combustion. Furthermore, it has been observed that this solution offers limited effectiveness when the lubricating composition includes viscosity-modifying polymers.

[0006] Application WO 2018 / 007497 describes lubricating compositions comprising polyol esters for lubricating gas engines and more particularly stationary gas engines exhibiting good detergency and oxidation resistance properties.

[0007] Application WO 2019 / 057718 describes the use of a marine engine lubricant composition comprising 2% to 12% by weight of an ester having a viscosity at 100°C between 200 and 1000 cSt, to improve engine cleanliness, the ester not being a glycerol ester.

[0008] There is therefore still an interest in providing ever more efficient lubricating compositions in terms of engine cleanliness, particularly for marine engines.

[0009] To this end, the invention relates to the use of at least one polyol ester(s) whose viscosity at 100°C, measured according to ASTM D445, is strictly less than 200 mm2 / s in a lubricating composition dedicated to a marine engine, to improve the cleanliness of said marine engine.

[0010] The invention also relates to the use of at least one polyol ester(s) whose viscosity at 100°C, measured according to ASTM D445, is strictly less than 200 mm2 / s to improve the detergency performance of a lubricant composition dedicated to a marine engine.

[0011] As can be seen from the following examples, the inventors have found that the implementation of an ester according to the invention in a lubricating composition advantageously improves the cleanliness of the marine engine lubricated by the lubricating composition containing said ester.

[0012] In the context of the present invention, improved engine cleanliness is defined by increasing the thermal stability of the lubricant, which in turn reduces varnish buildup on engine parts. The thermal stability of the lubricant is determined by the ECBT test as described later in this application.

[0013] It must be understood that the improvement in engine cleanliness is understood in relation to what is observed in the absence of ester according to the invention in the lubricating composition.

[0014] As can be seen from the following examples, the inventors have found that the implementation of an ester according to the invention, specific because of its viscosity at 100°C, makes it possible to improve the cleanliness of the marine engine lubricated by the lubricating composition containing said ester, unlike the implementation of an ester whose viscosity at 100°C is greater than 200 mm2 / s.

[0015] In the preceding paragraphs and in the remainder of the text, unless otherwise indicated, the term "ester according to the invention" shall refer to a polyol ester(s) meeting the aforementioned definition. The formulation of a lubricant (or lubricating composition) according to the invention may include the use of a single ester. according to the invention or a mixture of at least two distinct esters according to the invention. Examples of esters according to the invention are detailed later in the text.

[0016] Advantageously, an aforementioned lubricating composition (or lubricant) comprises from 1% to 15% by mass of polyol ester(s) according to the invention relative to the total mass of said lubricating composition.

[0017] The present invention also relates to the use of at least one polyol ester(s) as defined above in a lubricating composition dedicated to an engine, to improve the cleanliness of said engine, said lubricating composition comprising at least one olefin copolymer and / or at least one hydrogenated styrene and diene(s) polymer.

[0018] It was surprisingly observed by the inventors that the implementation of an ester according to the invention in such a lubricating composition makes it possible to improve the cleanliness of the engine lubricated by the lubricating composition containing said ester, despite the presence of these polymers which are known to be particularly fouling.

[0019] The present invention also relates to the aforementioned use, in which the lubricating composition as defined above also comprises one or more superbased detergent(s).

[0020] In particular, the present invention relates to the aforementioned use, in which the engine is a marine engine, preferably a 4-stroke marine engine.

[0021] Other features and variations of the use of ester according to the invention to improve engine cleanliness will become clearer from the description and examples that follow, given by way of illustration and not limitation of the invention.

[0022] In the following text, the expressions "between ... and ...", "ranging ... to ..." and "varying from ... to ..." are equivalent and are meant to mean that the limits are included, unless otherwise stated.

[0023] As indicated above, the present invention relates to the use of at least one polyol ester(s) whose viscosity at 100°C, measured according to ASTM D445, is strictly less than 200 mm2 / s, in a lubricating composition dedicated to a marine engine, to improve the cleanliness of said marine engine.

[0024] The present invention also relates to the use of a lubricating composition dedicated to a marine engine comprising at least one polyol ester(s) whose viscosity at 100°C, measured according to ASTM D445, is strictly less than 200 mm2 / s, to improve the cleanliness of said marine engine.

[0025] The present invention also relates to a method of lubricating a marine engine by using a lubricating composition comprising at least one polyol(s) ester whose viscosity at 100°C, measured according to ASTM D445, is strictly less than 200 mm2 / s, to improve the cleanliness of said marine engine.

[0026] The present invention also relates to a method for improving the cleanliness of a marine engine, comprising a step of lubricating said marine engine with a lubricating composition comprising at least one polyol ester(s) whose viscosity at 100°C, measured according to ASTM D445, is strictly less than 200 mm2 / s.

[0027] The esters used according to the invention are implemented in a lubricating composition. The lubricating composition used may comprise a single ester or a mixture of several esters as defined above.

[0028] Thus, the esters implemented within the framework of the invention are characterized by a kinematic viscosity measured at 100°C (or KV100), measured according to the ASTM D445 standard, strictly less than 200 mm2 / s (or 200 cSt).

[0029] According to one embodiment, the KV100 of the polyol(s) esters used according to the invention is preferably less than 100 mm2 / s, and preferably strictly less than 60 mm2 / s, and in particular less than or equal to 50 mm2 / s.

[0030] According to one embodiment, the KV100 of the polyol(s) esters used according to the invention is between 10 mm2 / s and 200 mm2 / s, preferably between 15 mm2 / s and 150 mm2 / s, and preferably between 20 mm2 / s and 100 mm2 / s, or even between 20 mm2 / s and 50 mm2 / s.

[0031] An ester used according to the present invention can be any type of ester obtained by reaction between one or more polyol(s) and one or more acid(s). The esters can in particular be chosen from mono-, di-, tri-, tetra-, pentaesters and hexaesters.

[0032] By "polyol" (or polyalcohol), we mean an alcohol bearing at least two hydroxyl functions, preferably comprising from 2 to 8 hydroxyl functions, more preferably from 2 to 6 hydroxyl functions, even more preferably from 3 to 6 hydroxyl functions.

[0033] Preferably, the polyols are thus diols, triols, tetraalcohols, pentaalcohols or even hexaalcohols.

[0034] According to one embodiment, the polyol carries 3 or 6 hydroxyl functions.

[0035] Preferably, the polyol has a linear or branched hydrocarbon chain, comprising from 1 to 30 carbon atoms, more preferably comprising from 3 to 25 carbon atoms, even more preferably from 3 to 18 carbon atoms.

[0036] According to one embodiment, the polyol has a hydrocarbon chain, linear or branched, preferably branched, comprising 3 to 10 carbon atoms.

[0037] Advantageously, the polyols are chosen from erythritol, trimethylolpropane, pentaerythritol, preferably trimethylolpropane or dipentaerythritol.

[0038] According to one embodiment, the polyol is not glycerol.

[0039] Within the framework of the present invention, the acid or acids from which a polyol ester according to the invention is formed can be chosen from monoacids (also called monocarboxylic acids) and polyacids (also called polycarboxylic acids).

[0040] For the purposes of the invention, the term "acid" can thus refer to a monoacid (or monocarboxylic acid) or a polyacid (or polycarboxylic acid).

[0041] By "polyacid", we mean an acid bearing at least 2 carboxylic acid functions, preferably comprising between 2 and 6 carboxylic acid functions, more preferably between 2 and 4 carboxylic acid functions.

[0042] Preferably, the acids are chosen from acid anhydrides, fatty acids and mixtures thereof. Advantageously, the fatty acids may be of bio-based origin.

[0043] Advantageously, the acid anhydrides are selected from ethanoic anhydrides, propanoic anhydrides, maleic anhydrides, phthalic anhydrides, cis-1,2,3,6-tetrahydrophthalic anhydrides, succinic anhydrides.

[0044] Advantageously, the fatty acids also comprise from 4 to 36 carbon atoms, preferably from 6 to 24 carbon atoms. These fatty acids may be saturated, monounsaturated and / or polyunsaturated.

[0045] According to a particular embodiment of the invention, the fatty acids from which polyol esters implemented according to the invention are formed are, for example, fatty acids derived from vegetable oil and can be saturated, mono- and / or polyunsaturated. They are chosen for example from caprylic, pelargonic, capric, undecylenic, lauric, tridecylenic, myristic, pentadecylic, palmitic, margaric, stearic, nonadecyl, arachic, heneicosanoic, behenic, tricosanoic, lignoceric, pentacosanoic, cerotic, heptacosanoic, montanic, nonacosanoic, melissic, hentriacontanoic, laceroic acids, and their derivatives and unsaturated fatty acids such as palmitoleic, oleic, erucic, nervonic, linoleic, α-linolenic, β-linolenic, β-linolenic, β-homo-β-linolenic, arachidonic, eicosapentaenoic, docosahexaenoic acids, and their derivatives.Preferably, the fatty acids are derived from the hydrolysis of triglycerides present in vegetable and animal oils, such as coconut, palm, olive, peanut, rapeseed, sunflower, soybean, castor, wood, corn, pumpkin, grapeseed, jojoba, sesame, walnut, hazelnut, almond, shea, macadamia, alfalfa, rye, safflower, coconut, cottonseed, flaxseed, beef tallow, or any mixture thereof. Natural oils may have been genetically modified to enrich their content of certain fatty acids, for example, high-oleic rapeseed or sunflower oil.

[0046] In a particular embodiment of the invention, the carbon chain of the acid anhydrides or fatty acids can be functionalized by one or more groups chosen from among carboxylic acids, amides, ureas, methanes, amines, polyisobutadienes and alcohols.

[0047] The polyol(s) esters implemented according to the invention can be mixed esters, that is to say esters obtained by mixing different alcohols and / or different acids.

[0048] Thus, preferably, the polyol(s) esters used according to the invention are obtained by reaction between one or more polyol(s) as defined above and one or more monoacid(s) or polyacid(s) as defined above.

[0049] According to one embodiment, the ester used according to the invention is not a glycerol ester.

[0050] According to one embodiment, a polyol(s) ester used according to the invention is formed between one or more polyol(s), saturated or unsaturated, linear or branched, in Cl to C16, and one or more mono- or polycarboxylic acid(s), saturated, linear or branched, in C2 to C36, in particular in C2 to C20, especially in C6 to C20.

[0051] According to one embodiment, a polyol(s) ester used according to the invention is formed between a polyol, saturated or unsaturated, linear or branched, in Cl to Cl6, and one or more monocarboxylic acid(s), saturated, linear or branched, in C6 to C20, said polyol comprising at least 3 hydroxyl groups, and in particular 3 to 6 hydroxyl groups.

[0052] Preferably, a polyol(s) ester used according to the invention is formed between a linear or branched aliphatic polyol, in Cl to Cl6, and one or more linear or branched aliphatic monocarboxylic acid(s), in C6 to C20, said polyol comprising at least 3 hydroxyl groups, and in particular 3 to 6 hydroxyl groups.

[0053] According to another embodiment, a polyol(s) ester used according to the invention is formed between one or more polyol(s), saturated or unsaturated, linear or branched, in Cl to C16, and one or more polycarboxylic acid(s), saturated, linear or branched, in C4 to C36, in particular in C6 to C20.

[0054] A polyol(s) ester used according to the invention can therefore be a complex ester, namely an ester resulting from the reaction between a polyacid, in particular a diacid, and a polyalcohol.

[0055] According to one embodiment, the polyol ester used according to the invention is a complex ester, for example obtained by an esterification reaction between:

[0056] (a) at least one C2-C36 linear or branched aliphatic dicarboxylic acid, in particularly in C2-C12;

[0057] (b) at least one aliphatic polyol, linear or branched, comprising 3 to 6 groups hydroxyl groups; and

[0058] (c) as a chain-stopping agent,

[0059] or, in the case of excess polyol (b), (cl) at least one C1-C30 linear or branched aliphatic monocarboxylic acid,

[0060] or, in case of excess acid (a), (c2) at least one C1-C30 linear or branched aliphatic monoalcohol.

[0061] These complex esters are described for example in document WO2015 / 059063.

[0062] Aliphatic dicarboxylic acids (a) are preferably linear. Aliphatic dicarboxylic acids (a) can be unsaturated or saturated, and are preferably saturated. Examples of aliphatic dicarboxylic acids (a) include ethanedioic (oxalic) acid, propanedioic (malonic) acid, butanedioic (succinic) acid, butenedioic (maleic or fumaric) acid, pentanedioic (glutaric) acid, pent-2-enedioic (glutaconic) acid, hexanedioic (adipic) acid, hexa-2,4-dienedioic (muconic) acid, heptanedioic (pimelic) acid, octanedioic acid, suberic acid, nonanedioic (azelaic) acid, decanedioic (sebatic) acid, undecanedioic acid, dodecanedioic acid or dodec-2-enedioic (traumatic) acid. A mixture of the above aliphatic dicarboxylic acids can also be used.

[0063] In a preferred embodiment, said aliphatic dicarboxylic acid(s) (a) is / are selected from linear C6 to C10 aliphatic dicarboxylic acids that are preferably saturated. More particularly, adipic acid or sebacic acid is used as acid (a).

[0064] Aliphatic polyols (b) can be branched or linear; they can be unsaturated or saturated, preferably saturated; they can contain carbon chains comprising from 3 to 12, preferably from 3 to 8, in particular from 4 to 6 carbon atoms and preferably 3, 4 or 5 hydroxyl groups. Examples of polyols (b) include trimethylolethane, trimethylolpropane, trimethylolbutane, trimethylolpentane, trimethylolhexane, trimethylolheptane, trimethyloloctane, trimethylolnonane, erythritol, threitol, arabitol, xylitol, ribitol, sorbitol, mannitol, galactitol, fucitol, iditol, inositol, volmitol, heptitols, glycerin, and pentaerythritol. The aforementioned aliphatic polyols may be of synthetic or natural origin. Mixtures of the aforementioned aliphatic polyols may also be used.

[0065] In a preferred embodiment, the aliphatic polyol (b) is selected from glycerin, trimethylolpropane and pentaerythritol.

[0066] Depending on whether component (b) is used for the esterification reaction in excess relative to component (a), resulting in remaining free hydroxyl groups, or whether component (a) is used for the esterification reaction in excess relative to component (b), resulting in remaining free carboxyl groups, the stopping agent The chain (cl) or (c2) is used for the synthesis of the aforementioned complex ester. The monocarboxylic acid component (cl) converts the remaining free hydroxyl groups into additional carboxylic ester groups. The monoalcohol component (c2) converts the remaining free carboxylic groups into additional carboxylic ester groups.

[0067] Aliphatic monocarboxylic acids (cl) can be branched or linear; they can be unsaturated or saturated, and are preferably saturated.Examples of monocarboxylic acids (cl) include formic acid, acetic acid, propionic acid, butanoic acid (butyric acid), pentanoic acid (valeric acid), 2,2-dimethylpropionic acid (neopentonoic acid), hexanoic acid, heptanoic acid (enanthic acid), octanoic acid (caprylic acid), 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, nonanoic acid, decanoic acid (capric acid), undecanoic acid, dodecanoic acid (lauric acid), tridecanoic acid, tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), isostearic acid, oleic acid, linoleic acid, linolenic acid, linohelaidic acid, erucic acid, arachidic acid, behenic acid, lignoceric acid, octacosanoic acid (montanic acid), tracontanoic acid (melissic acid) and cerotic acid.The aforementioned monocarboxylic acids, including fatty acids, may be of synthetic or natural origin. Mixtures of the aforementioned aliphatic monocarboxylic acids may also be used.

[0068] In a preferred embodiment, the aliphatic monocarboxylic acid (cl) is chosen from linear or branched aliphatic monocarboxylic acids in C8 to C18.

[0069] Monobasic aliphatic alcohols (c2) can be branched or linear; they can be unsaturated or saturated and are preferably saturated. Examples of aliphatic monoalcohols (c2) include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, 2-ethylhexanol, n-nonanol, 2-heptanol, n-nonanol, 2-propylheptanol, n-decanol, n-undecanol, n-dodecanol, n-tridecanol, iso-tridecanol, n-tetradecanol, iso-tetradecanol, n-hexadecanol, n-octadecanol, iso-octadecanol and n-eicosanol. Mixtures of the aforementioned monoalcohols can also be used.

[0070] In a preferred embodiment, the aliphatic monoalcohol (c2) is chosen from linear or branched C8 to Cl8 alkanols.

[0071] A complex ester as defined above can be prepared according to methods known to those skilled in the art. More specifically, it can be prepared by by mixing and reacting component (a) with (b), and then reacting the intermediate ester formed by (a) and (b) with component (c). It can also be prepared by simultaneously mixing and reacting components (a), (b) and (c).

[0072] The complex ester mentioned may be composed of at least 2 molecular units of component (a), at least 3 molecular units of component (b) and the corresponding number of molecular units of the chain-stopping agent (c), or of at least 2 molecular units of component (b), at least 3 molecular units of component (a) and the corresponding number of molecular units of the chain-stopping agent (c).

[0073] In a preferred embodiment, the complex ester referred to is composed of 2 to 9 molecular units, in particular 2 to 5 molecular units, of component (a) and 3 to 10 molecular units, in particular 3 to 6 molecular units, of component (b), component (b) being in excess of component (a), the remaining free hydroxyl groups of (b) being wholly or partially covered by a corresponding number of molecular units of component (cl).

[0074] In another preferred embodiment, the complex ester mentioned is composed of 3 to 10 molecular units, in particular 3 to 6 molecular units, of component (a) and 2 to 9 molecular units, in particular 2 to 5 molecular units, of component (b), component (a) being in excess of component (b), the remaining free carboxyl groups of (a) being wholly or partially covered by a corresponding number of molecular units of component (c2).

[0075] A typical complex ester useful for the present invention is composed of 3 or 4 molecular units of component (a), in particular of at least one linear C6 to C10 aliphatic carboxylic acid such as adipic acid and / or sebacic acid, 4 or 5 molecular units of component (b), in particular of glycerin, trimethylolpropane and / or pentaerythritol, and 6 to 12 molecular units of component (cl), in particular of at least one linear or branched C8 to Cl8 aliphatic monocarboxylic acid such as octanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, nonanoic acid, decanoic acid and / or isostearic acid.

[0076] According to an advantageous embodiment, the quantity of polyol ester(s) in the aforementioned lubricating composition is 1% to 15% by mass, preferably 2% to 15% by mass, relative to the total mass of said lubricating composition.

[0077] Preferably, the content of polyol ester(s) as defined above in the lubricating composition ranges from 2% to 10% by mass, preferably from 2% to 5% by mass, relative to the total mass of the lubricating composition.

[0078] The present invention therefore also relates to the use of at least one polyol ester(s) as defined above in a lubricating composition for a marine engine, to improve the cleanliness of said marine engine, wherein said composition lubricating compound comprises 2% to 10% by mass, preferably 2% to 5% by mass, of said polyol ester(s), relative to the total mass of the lubricating composition.

[0079] According to one embodiment, the aforementioned lubricating composition comprises at least one olefin copolymer and / or at least one hydrogenated styrene and diene(s) polymer, in particular a linear hydrogenated styrene / butadiene copolymer.

[0080] The lubricating composition used according to the invention may include, in addition to the aforementioned polyol(s) ester, at least one olefin copolymer.

[0081] These olefin copolymers can be copolymers based on ethylene and propylene motifs, or copolymers based on ethylene, propylene, and diene motifs (EPDM). Preferably, the olefin copolymer implemented according to the invention is an ethylene / propylene copolymer.

[0082] The olefin copolymer implemented according to the invention is in linear or star-shaped form, preferably in linear form. The olefin copolymer implemented according to the invention is in block form or in statistical form.

[0083] The olefin copolymer implemented according to the invention advantageously has an ethylene motif content ranging from 30% to 80% by mass, relative to the mass of olefin copolymer, preferably from 30% to 70%, more preferably from 40% to 70%.

[0084] The olefin copolymer implemented according to the invention also advantageously has an ethylene motif content ranging from 40% to 90% by mole, relative to the number of moles of olefin copolymer, preferably from 40% to 80%, more preferably from 50% to 80%.

[0085] The olefin copolymer implemented according to the invention advantageously has a propylene motif content ranging from 20% to 70% by mass, relative to the mass of olefin copolymer, preferably from 20% to 60%, more preferably from 20% to 50%.

[0086] The olefin copolymer according to the invention also advantageously has a propylene motif content ranging from 10% to 60% by mole, relative to the number of moles of olefin copolymer, preferably from 20% to 60%, more preferably from 20% to 50%.

[0087] The quantity of olefin copolymer in a lubricating composition according to the invention is, for example, from 0.01% to 5%, preferably from 0.1% to 3%, preferably from 0.2% to 2%, by mass relative to the total mass of the lubricating composition. This quantity refers to the amount of dry polymer matter. 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).

[0088] A lubricating composition used according to the invention may include, in addition to the aforementioned polyol ester, at least one copolymer of styrene and hydrogenated diene(s), in particular a linear hydrogenated styrene / butadiene copolymer.

[0089] The styrene and hydrogenated diene(s) copolymer (or styrene / hydrogenated diene(s) copolymer) according to the invention is a copolymer of styrene and one or more hydrogenated diene(s), and in particular a copolymer of styrene and a hydrogenated diene.

[0090] The hydrogenated styrene / diene(s) copolymer used according to the invention can be chosen from linear or star-shaped copolymers.

[0091] The hydrogenated styrene / diene(s) copolymer can be chosen from block copolymers or statistical copolymers.

[0092] Preferably, the content of hydrogenated diene motif(s) is 50% to 98%, preferably 60% to 98%, more preferably 70% to 97%, even more preferably 75% to 96% by mass, relative to the mass of the copolymer.

[0093] Preferably, the styrene motif content is from 2% to 50%, preferably from 2% to 40%, more preferably from 3% to 30%, even more preferably from 4% to 25% by mass, relative to the mass of the copolymer.

[0094] In one embodiment, the hydrogenated styrene / diene(s) copolymer used according to the invention has a weight average molecular mass Mw ranging from 100,000 g / mol to 800,000 g / mol, preferably from 200,000 g / mol to 700,000 g / mol, more preferably from 300,000 g / mol to 600,000 g / mol, even more preferably from 400,000 g / mol to 500,000 g / mol.

[0095] In one embodiment of the invention, the hydrogenated styrene / diene(s) copolymer used according to the invention has an average molecular mass in number Mn ranging from 50,000 g / mol to 800,000 g / mol, preferably from 75,000 g / mol to 600,000 g / mol, more preferably from 100,000 g / mol to 500,000 g / mol, even more preferably from 100,000 g / mol to 200,000 g / mol.

[0096] The measurement of the average number and weight molecular masses (Mn and Mw) is carried out by gel permeation chromatography (GPC).

[0097] The hydrogenated styrene / diene(s) copolymer used according to the invention has, for example, a dispersity index ranging from 1 to 4, preferably from 1.2 to 3.5, more particularly from 1.5 to 3.5, and preferably from 2 to 3.

[0098] Preferably, the hydrogenated styrene / diene(s) copolymer is used in an amount of 0.01% to 5%, preferably 0.1% to 3%, preferably 0.4% to 2%, and even more preferably 0.5% to 1%, by mass relative to the total mass of the lubricating composition.

[0099] This quantity refers to the quantity of active polymer material (dry extract). Indeed, the styrene and hydrogenated diene copolymer used in the The present invention can be in the form of a dispersion in a mineral or synthetic oil, and more particularly in a group I or III oil according to the API classification.

[0100] Preferably, the hydrogenated diene motif is a hydrogenated butadiene or hydrogenated isoprene motif, we then speak of a hydrogenated styrene / butadiene polymer or a hydrogenated styrene / isoprene polymer.

[0101] Preferably, the hydrogenated diene motif is a hydrogenated butadiene motif.

[0102] According to one embodiment, the hydrogenated styrene / diene copolymer is a linear hydrogenated styrene / butadiene copolymer.

[0103] In one embodiment of the invention, the linear hydrogenated styrene / butadiene copolymer can be selected from hydrogenated styrene / butadiene block copolymers or statistical hydrogenated styrene / butadiene copolymers, or mixtures thereof.

[0104] Advantageously, the linear hydrogenated styrene / butadiene copolymer has a hydrogenated butadiene motif content of 50% to 98% by mass, preferably 60% to 98%, more preferably 60% to 90%, relative to the mass of the linear hydrogenated styrene / butadiene copolymer.

[0105] Advantageously, the linear hydrogenated styrene / butadiene copolymer has a hydrogenated butadiene motif content of 50% to 98% by moles, preferably 60% to 98%, more preferably 70% to 97%, more preferably 70% to 95%, compared to the number of moles of the linear hydrogenated styrene / butadiene copolymer.

[0106] Advantageously, the linear hydrogenated styrene / butadiene copolymer has a styrene motif content ranging from 2% to 50%, preferably from 2% to 40%, more preferably from 10% to 40% by mass relative to the mass of the linear hydrogenated styrene / butadiene copolymer.

[0107] Advantageously, the linear hydrogenated styrene / butadiene copolymer has a styrene motif content ranging from 2% to 50%, preferably from 2% to 40%, more preferably from 5% to 30% by mole relative to the number of moles of the linear hydrogenated styrene / butadiene copolymer.

[0108] In one embodiment of the invention, the hydrogenated butadiene motifs are formed from 5% to 40% by mass of addition butadiene 1-4, preferably from 20% to 40% relative to the mass of butadiene motifs in the linear hydrogenated styrene / butadiene copolymer, and from 20% to 60% by mass of addition butadiene 1-2, preferably from 30% to 60% relative to the mass of butadiene motifs in the linear hydrogenated styrene / butadiene copolymer.

[0109] In another embodiment of the invention, the hydrogenated butadiene motifs are formed from 10% to 60% by mole of 1,4-addition butadiene, preferably 20% at 50% relative to the number of moles of butadiene motifs in the linear hydrogenated styrene / butadiene copolymer, and from 30% to 80% in moles of 1-2 addition butadiene, preferably from 40% to 60% relative to the number of moles of butadiene motifs in the linear hydrogenated styrene / butadiene copolymer.

[0110] Examples of linear hydrogenated styrene / butadiene copolymers according to the invention include the linear hydrogenated styrene / butadiene polymers marketed by the Lubrizol company.

[0111] In one embodiment of the invention, the amount of linear hydrogenated styrene / butadiene copolymer is 0.01% to 10%, preferably 1% to 8%, and more preferably 2% to 7%, by mass relative to the total mass of the lubricating composition. This amount refers to the amount of active polymer material. Indeed, the linear hydrogenated styrene / butadiene copolymer used in the context of the present invention can be in the form of a dispersion in a mineral or synthetic oil, and more particularly in an oil of group I, II, or III according to the API classification.

[0112] Preferably, a lubricating composition used according to the invention may comprise, in addition to the aforementioned polyol(s) ester, at least one olefin copolymer and one linear hydrogenated styrene / butadiene copolymer, said copolymers being as defined above.

[0113] According to one embodiment of the use according to the invention, a lubricating composition according to the invention also comprises one or more superbased detergent(s).

[0114] The detergents used in the lubricating compositions according to the present invention can be chosen from detergents known to those skilled in the art.

[0115] According to a particular embodiment of the invention, 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 metallic cation of an alkali or alkaline earth metal.

[0116] A detergent is considered over-based when the metal is present in excess (in a quantity greater than the stoichiometric amount). The excess metal, which gives the detergent its over-based character, is in the form of oil-insoluble metal salts. Over-based detergents thus take the form of micelles composed of insoluble metal salts kept in suspension in the lubricating composition by 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. Over-based detergents are then referred to as mixed-type detergents. if the micelles comprise several types of detergents, different from each other by the nature of their hydrophobic chain.

[0117] Preferably, the BN (Base Number measured according to ASTM D-2896) of the over-based detergents according to the invention is high, greater than 150 mg KOH / g, typically between 200 and 700 mg KOH / g, generally between 250 and 450 mg KOH / g.

[0118] The excess metal giving the detergent its over-basic character is in the form of oil-insoluble metallic salts, for example carbonate, hydroxide, oxalate, acetate, glutamate, preferably carbonate.

[0119] Over-based detergents comprising a single type of soluble metallic detergent salt will generally be named after the nature of the hydrophobic chain of the latter detergent.

[0120] Thus, they will be said to be of the carboxylate, phenate, salicylate, sulfonate, naphthenate type depending on whether this detergent is respectively a carboxylate, phenate, salicylate, sulfonate, or naphthenate.

[0121] Over-based detergents will be said to be of mixed type if the micelles comprise several types of detergents, different from each other by the nature of their hydrophobic chain.

[0122] For use in lubricating compositions according to the present invention, the oil-soluble metal salts will preferably be carboxylates, phenates, sulfonates, salicylates, and mixed phenate-sulfonate and / or salicylates of calcium, magnesium, sodium or barium.

[0123] The insoluble metal salts providing the overbasic character are alkali and alkaline-earth metal carbonates, preferably calcium carbonate.

[0124] The over-based detergents used in the lubricating compositions according to the present invention will preferably be carboxylates, phenates, sulfonates, salicylates and mixed phenate-sulfonate-salicylate detergents, over-based with calcium carbonate.

[0125] According to one embodiment, a lubricating composition according to the invention has a base number (BN or Base Number in English, characterizing the basicity), measured according to the ASTM D2896 standard, of 3 to 150 mg of KOH / g, preferably of 5 to 100 mg of KOH / g, and preferably of 10 to 50 mg of KOH / g.

[0126] As stated above, the aforementioned use relates to marine engines, preferably 4-stroke marine engines.

[0127] Thus, and particularly advantageously, the present invention relates to improving the cleanliness of marine engines, especially 2-stroke or 4-stroke marine engines. More specifically, the invention relates to improving the cleanliness of 4-stroke marine engines.

[0128] A lubricating composition used according to the invention may include, in addition to the ester according to the invention as defined above, one or more base oils, distinct from said esters according to the invention, in particular one or more group II and / or III base oils, as well as other additives, in particular as defined in the rest of the text.

[0129] These base oils can be chosen from among the base oils conventionally used in the field of lubricating oils, such as mineral, synthetic or natural, animal or vegetable oils or mixtures thereof.

[0130] 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 mixtures thereof.

[0131] [Tables 1] Saturates content Sulfur content Viscosity index (VI) Group I Mineral oils <90% > 0.03% 80 <VI < 120 Groupement II Huiles hydrocraquées >90% <0.03% 80 <VI < 120 Groupement 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

[0132] Mineral base oils include all types of base oils obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, desalpha removal, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing.

[0133] Mixtures of synthetic and mineral oils, which may be bio-based, may also be used.

[0134] In particular, a lubricating composition formulated according to the invention based on one or more esters as described above may further comprise one or more base oils selected from Group I, II, III and IV oils of the APL classification. In particular, a lubricating composition formulated according to the invention may comprise one or more Group I, II and / or III base oils, in particular several group II base oils, possibly in combination with one or more group I oils.

[0135] According to a particular embodiment, a lubricating composition formulated according to the invention based on one or more polyol ester(s) as described above comprises at least 10% by mass, in particular from 15% to 90% by mass and more particularly from 20% to 80% by mass, in particular from 40% to 75% by mass, in particular from 60% to 70% by mass, of one or more base oils distinct from said ester(s), in particular chosen from group I, II and / or III oils, in particular from group II and / or III, in particular from group II, relative to the total mass of said lubricating composition.

[0136] Preferably, the lubricating composition formulated according to the invention based on a polyol(s) ester as described above comprises a mixture of Group II base oils.

[0137] According to a particular embodiment, a lubricating composition formulated according to the invention based on a polyol(s) ester as described above comprises 50% to 80% by mass, preferably 60% to 75% by mass, and more particularly 65% ​​to 70% by mass, of Group II oils, relative to the total mass of said lubricating composition.

[0138] Preferably, the base oil or mixture of base oils of a lubricating composition formulated according to the invention has a kinematic viscosity measured at 100°C according to ASTM D445 ranging from 3 to 8 mm2 / s, in particular from 3.5 to 7 mm2 / s, relative to the total mass of said lubricating composition.

[0139] A lubricating composition implemented according to the invention may further comprise all types of additives suitable for use in an engine lubricant, in particular for marine engines.

[0140] In particular, a lubricating composition implemented according to the invention may include an anti-wear additive.

[0141] Anti-wear additives protect surfaces in contact by forming a protective film adsorbed onto these surfaces. There is a wide variety of anti-wear additives. Examples include phospho-sulfur additives, such as metallic alkylthiophosphates, in particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates (or ZnDTP). The alkyl groups of these zinc dialkyldithiophosphates preferentially contain from 1 to 18 carbon atoms. Amine phosphates and polysulfides, particularly sulfur olefins, are also commonly used anti-wear additives. Nitrogen and sulfur-containing anti-wear additives are also found, such as, for example, Metallic dithiocarbamates, particularly molybdenum dithiocarbamates. The preferred anti-wear additive is ZnDTP.

[0142] The mass content of anti-wear additive in a lubricating composition according to the invention can range from 0.1% to 5%, preferably from 0.2% to 4%, more preferably from 0.2% to 2% relative to the total mass of the lubricating composition.

[0143] In particular, a lubricating composition implemented according to the invention may include an anti-foaming additive.

[0144] Antifoaming additives can be chosen from polar polymers such as polymethylsiloxanes or polyacrylates.

[0145] These additives are generally present at a mass content of 0.01% to 3% relative to the total mass of the lubricating composition.

[0146] As additional additives for a lubricating composition as defined above, dispersants, friction modifiers, antioxidants, viscosity index improvers, pour point depressants, thickeners, and mixtures thereof may also be mentioned. These additives are common and well known to those skilled in the art. EXAMPLES

[0147] Example 1: Preparation of lubricating compositions with a polyol ester according to the invention

[0148] A first CCI lubricating composition intended for a 4-stroke marine engine was prepared by simply mixing, at room temperature, the following components, in the mass proportions indicated in Table 2 below.

[0149] [Tables 2] Components CCI Additive Package* 17.16 OCP Polymer (olefin copolymer) (5% wt. in Group I base oil) 5 SB H Polymer (linear hydrogenated styrene / butadiene copolymer) (8% wt. in Group I base oil) 6.9 Group II Base Oil 35.47 (KV100 = 4.4 cSt) Group II base oil (KV100 = 6.4 cSt) 35.47

[0150] *includes detergents, an anti-wear agent and an anti-foaming agent.

[0151] This lubricating composition is then used to prepare other lubricating compositions comprising a polyol ester according to the invention, namely a dipentaerythritol ester (ester 1) with a KV100 equal to 25 cSt.

[0152] These lubricating compositions are prepared by adding ester 1 to the CCI composition in the mass proportions indicated in Table 3 below.

[0153] [Tables3] Components CL1 CL2 CL3 CL4 CL5 CL6 CCI 99 98 96.5 95 90 85 Ester 1 1 2 3.5 5 10 15 BN (mg KOH / g) 29.7 29.4 28.95 28.5 27 25.5

[0154] Example 2: Evaluation of the properties of the lubricating compositions of Example 1

[0155] The thermal resistance of the lubricant compositions in Example 1 (CCI and CL1-CL6) was evaluated using the continuous ECBT test, which measures the mass of deposits (in mg) generated under specified conditions. The lower this mass, the better the thermal resistance and therefore the better the engine cleanliness.

[0156] This test simulates an engine piston brought to a high temperature and onto which lubricant from the crankcase is sprayed.

[0157] The test uses aluminum beakers that simulate the shape of pistons. These beakers were placed in a glass container, maintained at a controlled temperature of 20°C by circulating water. Lubricant was placed in these containers, which were themselves equipped with a wire brush partially immersed in the lubricant. This brush rotated at a speed of 1,000 revolutions per minute, creating a lubricant spray on the lower surface of the beaker. The beaker was maintained at a temperature of 310°C by an electric heating element regulated by a thermocouple.

[0158] In the ECBT Continuous test, the test lasted 12 hours and the lubricant application was continuous. This procedure simulates the formation of deposits in the piston-ring assembly. The result is the weight of deposits measured on the beaker (in mg).

[0159] A video rating also allows the percentage of varnish coverage (in %) to be determined.

[0160] A detailed description of this test is given in the publication entitled “Research and Development of Marine Lubricants in ELF ANTAR France - The relevance of laboratory tests in simulating field performance” by Jean-Philippe ROMAN, Marine Propulsion Conference 2000 - Amsterdam - 29-30 Tuesday 2000.

[0161] The results obtained are shown in Table 4 below.

[0162] [Tables4] Compositions CCI CL1 CL2 CL3 CL4 CL5 CL6 Depot in mg ECBT continuous 690 560 350 440 460 480 450 % coverage 99.6 91.8 82.5 80.0 87.0 84.3 64.5

[0163] The results show that the CL1-CL6 compositions according to the invention exhibit good thermal resistance (reduction / stabilization of deposits and of the surface covered) and thus make it possible to improve engine cleanliness.

[0164] Lubricating compositions therefore exhibit improved engine cleanliness properties due to the presence of the polyol ester according to the invention.

[0165] The lubricant compositions in Table 3 are then subjected to the ECBT Stop & Go test. This test is carried out according to the same principles as the continuous test as described above, but under cycling conditions.

[0166] This test reflects the behavior of the lubricant in the area of ​​the piston ring belt.

[0167] The tested products are sprayed into the beaker according to cyclic sequences in which the duration of the stop step is three times greater than the duration of the start step (15 repetitions of sub-cycles comprising one minute of lubricant spraying followed by three minutes of rest). The test temperatures are chosen between 270°C and 310°C, and the test duration is one hour. At the end of a cycle, the beaker cools naturally, without splashing, which greatly contributes to the formation of varnish. The final result of the Stop & Go test is based on a visual evaluation, according to a method described in the aforementioned publication by Jean-Philippe Roman.

[0168] The method is as follows: A video rating based on both the color of the varnish and the surface coverage rate is performed. The rating is given on a scale of 0 to 100 points. Curves showing the performance of each composition for at least three temperatures are plotted on a graph.

[0169] The critical temperature is also noted for each composition, corresponding to the temperature at which the rating obtained is equal to 80 out of 100.

[0170] The results of the Stop&Go test are shown in Table 5 below.

[0171] [Tables5] Compositions CCI CL1 CL2 CL3 CL4 CL5 CL6 Critical T (°C) 277 287 294 300 300 303 307

[0172] It is therefore also observed by this test that the presence of the polyol ester according to the invention (in compositions CL1-CL6) makes it possible to increase the critical temperature and therefore to improve the thermal stability of the lubricant under conditions which reflect those implemented at the level of the piston ring belt of a marine engine, and therefore to improve engine cleanliness.

[0173] Lubricating compositions therefore exhibit improved engine cleanliness properties due to the presence of the polyol ester according to the invention.

[0174] Example 3: Preparation of lubricating compositions with other polyol esters

[0175] The following polyol esters are also tested:

[0176] [Tableauxô] KV100 (cSt) Ester 2 (trimethylolpropane ester) 50 Ester 3 (complex ester) 37 Ester 4 (complex ester not part of the invention) 620

[0177] Esters 2 and 3 are polyol esters according to the invention, whereas ester 4 is not a polyol ester according to the invention because of its KV100 greater than 200 mm2 / s.

[0178] Lubricating compositions are prepared by adding these polyol esters to the CCI composition in the mass proportions indicated in Table 7 below.

[0179] [Tables7] Components CL4 CL7 CL8 CC2 CCI 95 95 95 95 Ester 1 5 - - - Ester 2 - 5 - - Ester 3 - - 5 - Ester 4 - - - 5 (excluding invention) BN (mg KOH / g) 28.5 28.5 28.5 28.5

[0180] Example 4: Evaluation of the properties of the lubricating compositions of example 3

[0181] The compositions of Example 3 are tested as indicated in Example 2, namely according to the continuous ECBT test and according to the ECBT Stop&Go test.

[0182] The results obtained are shown in Tables 8 and 9 below.

[0183] [Table 8] Continuous ECBT Test Compositions CCI CL4 CL7 CL8 CC2 Deposition in mg ECBT continuous 690 460 500 210 1,757

[0184] The results show that the CL7 and CL8 compositions comprising polyol esters according to the invention exhibit good thermal resistance (reduction / stabilization of deposits) and thus improve engine cleanliness.

[0185] These lubricating compositions therefore exhibit improved engine cleanliness properties due to the presence of polyol esters 2 and 3 according to the invention.

[0186] These results also show that the implementation of a polyol ester with a viscosity at 100°C greater than 200 cSt is not satisfactory. This polyol ester (not part of the invention) is in fact very fouling and therefore does not improve engine cleanliness.

[0187] [Table 9] ECBT Stop&Go Test Compositions CCI CL4 CL7 CL8 Critical T (°C) 277 300 284 295

[0188] This test confirms that the presence of polyol esters according to the invention (esters 2 and 3 in compositions CL7 and CL8) makes it possible to increase the critical temperature and therefore to improve the thermal stability of the lubricant under conditions which reflect those implemented at the level of the piston ring belt of a marine engine, and therefore to improve engine cleanliness.

[0189] These lubricating compositions therefore exhibit improved engine cleanliness properties due to the presence of polyol esters according to the invention.

[0190] Conversely, as with the continuous test, it is observed that the use of a polyol ester with a viscosity at 100°C exceeding 200 cSt is not satisfactory. This polyol ester (not part of the invention) is indeed very fouling and gives poor results.

Claims

Demands

1. Use of at least one polyol ester(s) having a viscosity at 100°C, measured according to ASTM D445, strictly less than 200 mm2 / s, preferably less than 100 mm2 / s, and preferably strictly less than 60 mm2 / s, and in particular less than or equal to 50 mm2 / s, in a lubricating composition intended for a marine engine, to improve the cleanliness of said marine engine.

2. Use according to claim 1, wherein the amount of polyol ester(s) is from 1% to 15% by mass, in particular from 2% to 10% by mass, in particular from 2% to 5% by mass, relative to the total mass of the lubricating composition.

3. Use according to claim 1 or 2, wherein the lubricating composition comprises at least one olefin copolymer and / or at least one hydrogenated styrene and diene(s) polymer.

4. Use according to claim 3, wherein the amount of olefin copolymer is from 0.01% to 5%, preferably from 0.1% to 3%, preferably from 0.2% to 2%, by mass relative to the total mass of the lubricating composition.

5. Use according to claim 3 or 4, wherein the amount of styrene polymer and hydrogenated diene(s) is from 0.01% to 5%, preferably from 0.1% to 3%, preferably from 0.4% to 2%, and further preferably from 0.5% to 1%, by mass relative to the total mass of the lubricating composition.

6. Use according to any one of the preceding claims, wherein the lubricating composition comprises one or more over-based detergent(s), in particular selected from alkali metal salts, alkaline earths of carboxylic acids, sulfonates, salicylates, naphthenates, phenates, carboxylates.

7. Use according to any one of the preceding claims, wherein the lubricating composition has a number of BN bases, measured according to ASTM D2896, of 3 to 150 mg KOH / g, preferably 5 to 100 mg KOH / g, and preferably 10 to 50 mg KOH / g.

8. Use according to any one of the preceding claims, wherein the engine is a 4-stroke marine engine.

9. Use according to any one of the preceding claims, wherein the polyol(s) ester is formed between one or more polyol(s), saturated or unsaturated, linear or branched, in C16 to C16, and one or more mono- or polycarboxylic acid(s), saturated, linear or branched, in C2 to C36, in particular in C2 to C20, especially in C6 to C20.

10. Use according to claim 9, wherein the polyol(s) ester is formed between a polyol, saturated or unsaturated, linear or branched, in Cl to C16, and one or more monocarboxylic acid(s), saturated, linear or branched, in C6 to C20, said polyol comprising at least 3 hydroxyl groups, and in particular 3 to 6 hydroxyl groups.

11. Use according to claim 9, wherein the polyol(s) ester is formed between one or more polyol(s), saturated or unsaturated, linear or branched, in C1 to C16, and one or more polycarboxylic acid(s), saturated, linear or branched, in C4 to C36, in particular in C6 to C20.

12. Use according to any one of the preceding claims, wherein the lubricating composition comprises one or more base oil(s), in particular of group I, II and / or III, preferably of group II.

13. Use according to any one of the preceding claims, wherein the lubricating composition further comprises one or more additives selected from anti-wear additives, anti-foaming additives, dispersants, friction modifier additives, antioxidants, viscosity index improvers, pour point depressants, thickeners, and mixtures thereof.