Spiro compound as a detergent additive in marine engine lubricants

Abstract

Spiro compound as detergent additive in lubricants for marine engines The present application relates to the use, as detergent additive in a lubricating composition intended for a marine engine, of at least one spiro compound of formula (I) in which M is an atom chosen from boron and aluminum; n1 and n2 are, independently of one another, 0, 1 or 2; and R represent, independently of one another, a hydrocarbon group comprising from 1 to 50 carbon atoms, in particular from 5 to 20 carbon atoms. It also relates to the use of said spiro compound as an additive in a lubricating composition intended for a marine engine, to improve the oxidation stability of said lubricating composition.Finally, it relates to a lubricating composition intended for the lubrication of a marine engine, comprising one or more base oils and at least one spiro compound of formula (I), as well as a method for lubricating a marine engine using such a composition.

Description

Title of the invention: Spiro compound as a detergent additive in marine engine lubricants Technical field

[0001] The present invention relates to the field of lubricating compositions, and more particularly to the field of lubricating compositions intended for the lubrication of marine engines, in particular two-stroke or four-stroke marine engines. It relates more particularly to the use of spiro compounds as detergent additives in lubricants for marine engines.

[0002] Advantageously, the invention makes it possible to provide a lubricant having excellent detergency and oxidation stability properties, while maintaining a low ash content. Prior art

[0003] Marine engines, such as two-stroke or four-stroke marine engines, use lubricants, also called "marine oils", to lubricate the various parts of the engine. For example, slow two-stroke crosshead marine engines use, on the one hand, "cylinder" oils to lubricate the piston-cylinder assembly or the piston-ring-liner area and, on the other hand, "system" oils to lubricate all moving parts other than the piston-cylinder assembly or outside the piston-ring-liner assembly.

[0004] Until recently, basicity was a decisive criterion in the formulation of lubricating oils, particularly cylinder oils. Indeed, the lubricating oils within the piston-cylinder assembly are in contact with fuel combustion residues, these residues being able to contain, when they come from fuels with a high sulfur content, significant quantities of acid gases. In fact, during the combustion of fuels with a high sulfur content, acid gases are formed: these are in particular sulfur oxides (SO2, SO3), which are then hydrolyzed, upon contact with the moisture present in the combustion gases and / or in the oil, to generate sulfurous acid (HSO3) or sulfuric acid (H2SO4).

[0005] The neutralization capacity of lubricating oils, expressed by its base number (or BN or “Base number” in English terminology, sometimes called TBN for “Total Base Number” in English terminology), measured according to the ASTM D-2896 standard, was thus a selection criterion, making it possible to adjust the basicity of the lubricant used to the sulfur content of the fuel used, in order to be able to neutralize all of the sulfur contained in the fuel and likely to be transformed into sulfuric acid by combustion. Thus, the higher the sulfur content of a fuel, the higher the BN of the marine lubricant should be. Commercially available marine lubricants can thus have BNs of up to 140 mg KOH / g-

[0006] The desired basicity for the lubricant was conventionally provided by detergents overbased by insoluble metal salts, in particular metal carbonates such as calcium carbonate. These detergents are in particular metal soaps of the salicylate, phenate, sulfonate, carboxylate type, which form micelles where the particles of insoluble metal salts are kept in suspension. Part of the BN can also be provided by non-overbased or “neutral” metal detergents.

[0007] With new engines and new fuels, the basicity of the lubricant required to meet new needs is no longer so critical, and even a reduction in conventional overbased detergents becomes necessary.

[0008] In fact, new regulations established in light of environmental concerns have imposed limitations in terms of sulfur levels in fuels used on ships, which also implies reducing the content of metallic detergents in marine engine lubricating oils.

[0009] Indeed, an excess of metallic detergents, and therefore of basic sites, compared to a low sulfur fuel used, is likely to induce a risk of destabilization of the unused overbased detergent micelles, which contain insoluble metallic salts. This destabilization can result in the formation of deposits of insoluble metallic salts (typically, calcium carbonate) and having a high hardness, mainly on the piston crown of the engine and, in the long term, can lead to a risk of excessive wear of the liner polishing type.

[0010] It is known that sulfated ash, along with phosphorus and sulfur, can damage the exhaust gas aftertreatment systems that are now fitted to all new vehicles to eliminate harmful emissions such as NOx, CO or soot.

[0011] Also, a filter clogged with unburned material can lead to increased fuel consumption and thus results in fuel waste, which is contrary to the desired properties in terms of reducing marine fuel consumption.

[0012] Thus, it appears necessary to reduce the content of metallic detergents, in particular overbased metallic detergents, typically based on calcium carbonate, used in marine lubricants.

[0013] However, a decrease in the metallic detergent content also results in reducing the detergent capabilities of the lubricants below the required levels.

[0014] However, it is essential that lubricants for marine engines, being in direct contact with the engine, and in particular with the hot part of the engine, such as for example the piston-cylinder assembly, have good stability at high temperatures, in order to reduce or prevent the formation of deposits on the surface of metal parts, which are harmful to the engine.

[0015] Consequently, there is a need to have new compounds, alternatives to metallic detergents, in particular to overbased metallic detergents, capable of providing the marine lubricant with the desired detergency properties, while generating little ash, and thus making it possible to ensure, under the high temperature conditions encountered in marine engines, good properties in terms of engine cleanliness.

[0016] For example, document WO 2014 / 180843 proposes a cylinder lubricant for a marine engine, usable with both high-sulfur fuel oils and low-sulfur fuel oils, and having in particular good thermal resistance, combining a metallic detergent overbased by metallic carbonate salts, a neutral detergent and a specific BN fatty amine, in particular a tetra-amine.

[0017] Applications WO 2018 / 220007 and WO 2018 / 220009 propose, for example, the use of compounds derived from salicylic acid, products of the reaction between salicylic acid, a boron compound and an amine compound, for example of the polyamine type, for formulating lubricating compositions for marine engines, in particular for two-stroke marine engines, combining good anti-corrosion properties, wear resistance and good detergency performance. Statement of the invention

[0018] The present invention aims to provide a means for providing a lubricant, intended for the lubrication of a marine engine, with excellent detergency properties while having a low impact on the ash content.

[0019] More particularly, the invention relates, according to a first of its aspects, to the use, as a detergent additive in a lubricating composition intended for a marine engine, for example a two-stroke or four-stroke engine, of at least one spiro compound of the following formula (I):

[0020] [Chem.l]

[0021] in which: M is an atom selected from boron (B) and aluminum (Al), in particular is a boron atom; ni and n2 are, independently of each other, 0, 1 or 2; and R represent, independently of one another, a hydrocarbon group comprising from 1 to 50 carbon atoms, in particular from 5 to 20 carbon atoms.

[0022] By "detergent additive" within the meaning of the present invention, is meant a compound which, introduced into a lubricating oil, makes it possible to provide and / or increase its detergent capacities and therefore to reduce, prevent or even eliminate deposits in the engine.

[0023] In the remainder of the text, a spiro compound of formula (I) as defined above will be referred to more simply as a "spiro compound" according to the invention. Examples of spiro compounds considered according to the invention are described more precisely in the remainder of the text.

[0024] The term "marine lubricant" more simply refers to a lubricant intended for the lubrication of a marine engine. The marine lubricants considered according to the invention are suitable for use in the lubrication of two-stroke or four-stroke marine engines, in particular for two-stroke marine engines.

[0025] This may be a lubricant called a "cylinder lubricant" used for the lubrication of the piston-cylinder assembly of the engine, a lubricant called a "system lubricant", used for the lubrication of all the moving parts of the engine other than the piston-cylinder assembly, or a lubricant called a "crankcase lubricant" used for the lubrication of the entire engine, including the piston-cylinder assembly, in particular in a 4-stroke engine.

[0026] In another of its aspects, the invention further relates to a lubricating composition for lubricating a marine engine, in particular a two-stroke or four-stroke engine, comprising at least: - one or more base oils; - at least one spiro compound of formula (I) as defined above and detailed in the following text.

[0027] According to a particular embodiment, a lubricating composition according to the invention comprises, in addition to the said spiro compounds according to the invention, one or more other detergent additives, in particular chosen from the metallic detergent additives conventionally used in the field of lubricants, in particular based on calcium or magnesium.

[0028] As illustrated in the examples which follow, the inventors have discovered that the use of a spiro compound according to the invention makes it possible to obtain a marine lubricant having equivalent, and even improved, thermal resistance properties compared to a lubricant incorporating conventional metallic detergents, and therefore to ensure good engine cleanliness, in particular of the piston ring-cylinder area.

[0029] The detergency properties of the marine lubricant can be assessed by evaluating the performance of the lubricant in terms of thermal resistance by ECBT type tests, as described 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 MARCH 2000.

[0030] These tests account for the tendency of the marine lubricant to form deposits / varnishes under the conditions encountered during its use in a marine engine, in particular in the segment-piston-cylinder area of ​​the engine.

[0031] On the other hand, said spiro compound(s), used as detergent additives according to the invention, generate little ash compared to conventional metallic detergents.

[0032] Therefore, the incorporation into a marine lubricant of one or more spiro compounds according to the invention advantageously makes it possible to increase the detergency capacities of the lubricant, without negatively impacting the ash content generated by the lubricant.

[0033] Advantageously, as illustrated in the examples, it is possible to use one or more spiro compounds according to the invention, to partially replace the metallic detergents conventionally used in a marine lubricant and undesirable given the ash they generate, while retaining, or even improving, the thermal resistance of the marine lubricant, and therefore its detergency capacity.

[0034] Advantageously, it is thus possible to reduce the harmful effects in terms of ash levels, in particular sulfated ash, linked to the use of metallic detergents, in particular overbased detergents, without impacting, or even improving, the thermal resistance and detergency properties of the lubricant.

[0035] A lubricating composition according to the invention thus makes it possible to combine excellent detergency properties and a low ash content, in particular sulfated ash.

[0036] Advantageously, the use of a spiro compound according to the invention thus makes it possible to obtain a marine lubricating composition having good properties in terms of engine cleanliness, in particular in the ring-piston-cylinder zone of a marine engine, in particular of the piston-cylinder assembly.

[0037] Advantageously, as illustrated in the examples, the use of a spiro compound according to the invention also makes it possible to significantly increase the oxidation stability of the marine lubricant.

[0038] Thus, the implementation of a spiro compound according to the invention makes it possible to obtain a marine lubricant which, under the temperature conditions encountered in marine engines, has excellent thermal resistance, engine cleanliness and oxidation stability properties, with a reduced ash content.

[0039] The invention also relates to a process or method for increasing the detergency capacity of a lubricating composition intended for a marine engine, in particular of a lubricating composition using a reduced content of metallic detergents, in particular calcium carbonate, or even free of metallic detergent, comprising the addition to said lubricating composition of at least one spiro compound according to the invention.

[0040] The process or method according to the invention advantageously makes it possible to increase the detergency capacity of said composition, while maintaining a low ash content.

[0041] The invention also relates, according to another of its aspects, to a process or method for detergency of a marine engine, in particular a four-stroke or two-stroke engine, comprising a step of bringing at least one mechanical part of said marine engine, in particular at least part of the rings, piston and / or cylinder of said marine engine, into contact with a lubricating composition according to the invention as defined above.

[0042] It also relates to the use of at least one spiro compound according to the invention in a lubricant intended for the lubrication of a marine engine, in particular the piston-cylinder assembly of a marine engine, to improve engine cleanliness.

[0043] The invention also relates, according to another of its aspects, to a process or method for lubricating a marine engine, in particular a four-stroke or two-stroke engine, comprising a step of bringing at least one mechanical part of said marine engine, in particular at least part of the rings, piston and / or liner of said marine engine, into contact with a lubricating composition as defined above.

[0044] Other characteristics, variants and advantages of the use of a spiro compound according to the invention for the formulation of a marine lubricant will emerge more clearly on reading the description and examples which follow, given by way of illustration and not limitation of the invention.

[0045] In the remainder of the text, the expressions “between ... and ...”, “ranging from ... to ...” and “varying from ... to ...” are equivalent and are intended to mean that the limits are included, unless otherwise stated. Detailed description SPIRO Compound

[0046] As indicated previously, the invention is based on the use, in a marine engine lubricant, of one or more specific spiro compounds, as detergent additive(s).

[0047] It is understood that the invention can implement a single spiro compound or a mixture of at least two distinct spiro compounds, in particular three or four distinct spiro compounds, in particular as defined below.

[0048] As mentioned previously, the spiro compound considered according to the invention is of the following formula (I):

[0049] [Chem.2]

[0050] in which: M is an atom selected from boron and aluminum, in particular is a boron atom; ni and n2 are, independently of each other, 0, 1 or 2; and R represent, independently of one another, a hydrocarbon group comprising from 1 to 50 carbon atoms, in particular from 5 to 20 carbon atoms.

[0051] The hydrocarbon groups considered according to the invention may optionally be interrupted by one or more heteroatoms, for example -O-, -NH-, -N= or -S-, in particular -O- or -NH-; and / or optionally substituted by one or more -OH, -NH2 and -SH groups, in particular -OH or -NH2.

[0052] According to a particular embodiment, the groups R1 and R2 are composed solely of carbon and hydrogen atoms.

[0053] The hydrocarbon groups may in particular be alkyl, alkenyl, aryl or aralkyl groups.

[0054] According to a particular embodiment, the substituents R represent, independently of one another, a hydrocarbon group, preferably an aliphatic chain, linear or branched, comprising from 3 to 50 carbon atoms, in particular from 3 to 30 carbon atoms, in particular from 5 to 25 carbon atoms and more particularly from 8 to 20 carbon atoms.

[0055] In particular, the substituents R may represent, independently of one another, a linear or branched aliphatic chain, in particular an alkyl chain, preferably linear, from C1 to C50; in particular from C3 to C30, in particular from C5 to C23 and more particularly from C8 to C20, for example from C10 or from C16.

[0056] According to a particular embodiment, n1 and n2 are equal to 0.

[0057] According to another particular embodiment, n1 and n2 are equal to 1 or 2.

[0058] When ni is 2 or n2 is 2, the R groups, carried by the same cycle, may be the same or different.

[0059] In particular, the spiro compound may be of formula (I) above, in which n1 and n2 are 1; the substituents R may be identical or different, preferably identical.

[0060] According to a particular embodiment, the spiro compound is of formula (I) above, in which: ni and n2 are 1; and the R groups, which are identical, represent alkyl groups, preferably linear, from C1 to C50, in particular from C3 to C30, in particular from C5 to C23 and more particularly from C8 to C20, even more preferably from C16.

[0061] According to a preferred embodiment, the spiro compound is of formula (I) in which M is a boron atom.

[0062] In other words, according to this particular embodiment, the spiro compound can be a so-called spiroboronate compound, of the following formula (!):

[0063] [Chem.3]

[0064] in which R, n1 and n2 are as defined above.

[0065] According to another particular embodiment, the spiro compound is of formula (I) in which M is an aluminum atom.

[0066] In other words, according to this particular embodiment, the spiro compound can be a so-called spiroaluminate compound, of the following formula (I”):

[0067] [Chem.4]

[0068] in which n1, n2 and R are as defined above.

[0069] The invention thus relates, according to another of its aspects, to a spiro compound of formula (I) above, in which: - M is an aluminum atom; - ni and n2 are, independently of each other, 0, 1 or 2, at least one of ni and n2 being 1 or 2; preferably ni and n2 are 1; - the R groups represent, independently of one another, an aliphatic chain, linear or branched, in particular an alkyl chain, preferably linear, comprising from 5 to 50 carbon atoms, in particular from 6 to 30 carbon atoms, in particular from 8 to 25 carbon atoms and more particularly from 10 to 20 carbon atoms.

[0070] In other words, the invention relates to a spiroaluminate type compound of formula (I”) above, in which: - ni and n2 are, independently of each other, 0, 1 or 2, at least one of ni and n2 being 1 or 2; preferably ni and n2 are 1; and - the R groups represent, independently of one another, an aliphatic chain, linear or branched, in particular an alkyl chain, preferably linear, comprising from 5 to 50 carbon atoms, in particular from 6 to 30 carbon atoms, in particular from 8 to 25 carbon atoms and more particularly from 10 to 20 carbon atoms.

[0071] According to a particular embodiment, the spiroaluminate type compound according to the invention is of formula (I”) in which: - ni and n2 are equal to 1; and - the R groups, identical or different, preferably identical, represent alkyl chains, preferably linear, comprising from 5 to 50 carbon atoms, in particular from 6 to 30 carbon atoms, in particular from 8 to 25 carbon atoms and more particularly from 10 to 20 carbon atoms.

[0072] The spiro compound used according to the invention can be prepared from salicylic acid or a salicylic acid derivative and a boron compound or an aluminum compound.

[0073] More particularly, it can be obtained by reaction: - at least one compound chosen from salicylic acid and its derivatives, of the following formula (Ia):

[0074] [Chem.5]

[0075] in which R is as defined above and n is as defined above for n1 and n2; and - at least one boron or aluminum compound, in particular boric acid or aluminum hydroxide.

[0076] The preparation of the spiro compound used in the lubricating composition according to the invention does not involve any step, subsequent to the reaction of salicylic acid or one of its derivatives with said boron or aluminum compound, of reaction with an amine compound, as is the case for example in the context of the preparation of the compounds proposed in applications WO2018 / 220007 and WO2018 / 220009.

[0077] Salicylic acid and its derivatives of formula (Ia) above can be synthesized according to synthesis methods known to those skilled in the art or be commercially available.

[0078] The boron compound (in other words, based on boron) can be chosen in particular from boric acid (B(OH)3), boronic acids, boric and boronic esters, boron oxide and boric acid complexes.

[0079] In particular, the boron compound may be chosen from boric acid; boron oxide; boric acid complexes; trialkyl borates, in particular in which the alkyl groups comprise, independently of one another, from 1 to 4 carbon atoms; boronic acids having a CrCi2 alkyl group; boric acids substituted by two alkyl groups, in particular C1 to C12; boric acids substituted by two aryl groups, in particular C6 to C12; boric acids substituted by one or two aralkyl groups, in particular C7 to C12, and derivatives of these compounds obtained by substitution of at least one alkyl group by one or more alkoxy groups.

[0080] Boric acid complexes are in particular complexes of boron with one or more molecules comprising one or more alcohol functions.

[0081] According to a particular embodiment, the boron compound is boric acid.

[0082] The aluminum compound (in other words, aluminum-based) may in particular be chosen from aluminum hydroxide (A1(OH)3), aluminum oxide, aluminum sulfate (A12SO4)3.

[0083] It is up to the person skilled in the art to adjust the reaction conditions between said compound(s) (Ia) and the boron or aluminum compound to obtain the desired spiro compound.

[0084] In particular, the reaction can be carried out in a solvent medium consisting of one or more apolar solvents and / or protic polar solvents.

[0085] The solvent medium can be constituted of one or more solvents chosen from naphtha, protic polar solvents such as water and alcohols, for example methanol, ethanol, propanol, butanol; and their mixtures.

[0086] In the context of the invention, the following terms are understood to mean: - "hydrocarbon group", a saturated or unsaturated, linear, branched or cyclic, aromatic or non-aromatic radical comprising carbon and hydrogen; - "aliphatic chain", a hydrocarbon group consisting exclusively of carbon and hydrogen atoms, linear or branched, saturated or unsaturated, non-aromatic. Preferably, an aliphatic chain is an alkyl chain - "alkyl", a saturated aliphatic group, linear or branched; for example, a Cx to Cz alkyl represents a saturated carbon chain of x to z carbon atoms, linear or branched; - - “alkenyl” means a mono- or polyunsaturated, linear or branched aliphatic group; - “cycloalkyl”, a cyclic alkyl group, for example a Cx to Cz cycloalkyl represents a cyclic carbon group of x to z carbon atoms, for example a cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl; - “aryl”, a mono- or polycyclic aromatic group, in particular comprising between 6 and 10 carbon atoms. Examples of aryl groups include phenyl or naphthyl groups; - “aralkyl”, an aryl group as defined above, substituted by at least one alkyl group as defined above.

[0087] Said spiro compound(s) are advantageously used in a sufficient content to achieve the required level of detergency capacity of the marine lubricant. Advantageously, even a small amount of spiro compound(s), in particular less than 3% by mass, relative to the total mass of said lubricating composition, makes it possible to achieve the required detergency capacity, even in the absence of metallic detergents such as calcium-based detergents.

[0088] Of course, the quantity used in spiro compound(s) can be adjusted according to the composition of the marine lubricant, and more particularly taking into account the presence or absence and the quantity used in other detergent additive(s), in particular metallic additives, for example overbased and / or neutral detergents based on calcium, present in the lubricant.

[0089] Generally speaking, the said spiro compound(s) considered according to the invention, in particular as defined above, can be used in an amount of 0.1 to 20% by mass, in particular 0.2 to 15% by mass, in particular 0.5 to 10%, and more particularly 0.5 to 5% by mass, relative to the total mass of the said marine lubricating composition. LUBRICATING COMPOSITION

[0090] A lubricating composition for marine engines as considered according to the invention more particularly comprises one or more base oils and, optionally, other additives conventionally considered in marine lubricants.

[0091] It is understood that the nature and quantity of the other additives are adapted with regard to the destination of the lubricant, and more particularly with regard to the type of marine engine for which it is intended. Base oil

[0092] Conventionally, a marine lubricant according to the invention comprises one or more base oils.

[0093] These base oils can be chosen from base oils conventionally used in the field of marine lubricants, such as mineral, synthetic or natural, animal or vegetable oils or their mixtures.

[0094] It may be a mixture of several base oils, for example a mixture of two, three or four base oils.

[0095] The base oils of the marine lubricants considered 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) and presented in table A below or their mixtures.

[0096] [Tables 1] Saturates content Sulphur 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 Table A

[0097] 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, dealphating, solvent dewaxing, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing. Examples of Group I mineral bases are those called Neutral Solvent bases (such as, for example, 150NS, 330NS, 500NS or 600NS) or Brightstock.

[0098] 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 according to the ASTM D5296 standard.

[0099] Mixtures of synthetic and mineral oils, which can be bio-sourced, can also be used.

[0100] There are generally no limitations on the use of different base oils in the lubricating composition, except that they must have different properties, such as viscosity, viscosity index, sulfur content or resistance. resistance to oxidation, suitable for use in the lubrication of marine engines.

[0101] In particular, the lubricating compositions according to the invention have a viscosimetric grade SAE-20, SAE-30, SAE-40, SAE-50 or SAE-60 according to the SAEJ300 classification, equivalent to a kinematic viscosity at 100°C of between 5.6 and 26.1 mm2 / s measured according to the ASTM D445 standard.

[0102] Grade 40 oils have a kinematic viscosity, measured according to ASTM D445, at 100°C of between 12.5 and 16.3 mm2 / s. Grade 50 oils have a kinematic viscosity, measured according to ASTM D445, at 100°C of between 16.3 and 21.9 mm2 / s. Grade 60 oils have a kinematic viscosity, measured according to ASTM D445, at 100°C of between 21.9 and 26.1 mm2 / s.

[0103] The base oil(s) may be present in a lubricating composition according to the invention in a content of at least 50% by mass, relative to its total mass, in particular at least 60% by mass, more particularly ranging from 65 to 99% by mass and preferably from 70 to 98% by mass, for example ranging from 65% to 95% by mass. ADDITIVES

[0104] A lubricating composition according to the invention may comprise all types of additives usually used in marine lubricants.

[0105] 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.

[0106] 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.

[0107] These additives, distinct from said spiro compound(s), may in particular be chosen from other detergent additives, distinct from said spiro compound(s), in particular overbased and neutral metallic detergent additives, basic organic additives improving the total base number (TBN), anti-wear additives, dispersant additives, a viscosity index (VI) improver, thickeners, anti-foaming agents, antioxidant additives, anti-rust additives and mixtures thereof. Other detergents

[0108] A marine lubricant considered according to the invention, incorporating one or more spiro compounds according to the invention, in particular as defined above, may comprise one or more other detergent additives, in particular one or more metallic detergent additives.

[0109] As previously mentioned, metallic detergents are known to those skilled in the art to provide high levels of detergency. These metallic compounds However, they have the disadvantage of generating sulfated ash.

[0110] These are generally anionic compounds comprising a long lipophilic hydrocarbon chain and a hydrophilic head, the associated cation possibly being a metal cation of an alkali or alkaline earth metal.

[0111] They are generally chosen from alkali metal or alkaline earth metal salts of carboxylic acids, in particular sulfonates, salicylates, naphthenates, phenates, carboxylates and mixtures thereof. The alkali and alkaline earth metals are preferably calcium, magnesium, sodium or barium.

[0112] These metal salts generally comprise the metal in a stoichiometric quantity (we then speak of non-overbased or "neutral" detergents), or in excess, therefore in a quantity greater than the stoichiometric quantity. In the latter case, these are overbased detergent additives; the excess metal providing the overbased character to the detergent additive is then generally in the form of a metal salt insoluble in the base oil, for example a carbonate, a hydroxide, an oxalate, an acetate, a glutamate, preferably a carbonate.

[0113] According to a particular embodiment, a marine lubricant according to the invention comprises at least one metallic detergent additive, distinct from said spiro compound(s), in particular at least one overbased detergent additive and / or at least one neutral detergent additive.

[0114] In particular, the overbased detergent and / or the neutral detergent are compounds based on metals chosen from calcium, magnesium, sodium and barium, preferably based on calcium or magnesium.

[0115] Preferably, the overbased detergent is overbased with insoluble metal salts chosen from the group of alkali and alkaline earth metal carbonates, preferably calcium carbonate.

[0116] The overbased detergent used in a marine lubricant according to the invention may in particular be chosen from phenates, sulfonates, salicylates, carboxylates and mixed detergents (phenates-sulfonates-salicylates) overbased with calcium carbonate, more particularly by sulfonates and phenates overbased with calcium carbonate.

[0117] The content of metallic detergents, in particular overbased detergents and / or neutral detergents as described above, included in a marine lubricant according to the invention can in particular be adjusted so as to achieve the desired value of the total base number of the lubricant.

[0118] In particular, a marine lubricant according to the invention may have a total base number, TBN, measured according to the ASTM D2896 standard, less than or equal to 140 mg KOH per gram of lubricant, in particular between 5 and 140 mg KOH / g of lubricant, in in particular between 5 and 100 mg KOH / g of lubricant, in particular between 10 and 60 mg KOH / g of lubricant.

[0119] According to a particular embodiment, a marine engine lubricant according to the invention comprises at least: - one or more base oils; - at least one spiro compound according to the invention; and - at least one metallic detergent additive distinct from said spiro compound, in particular at least one overbased detergent and / or one neutral detergent as defined above, in particular based on calcium or magnesium.

[0120] Advantageously, as indicated above, by the addition of one or more spiro compounds according to the invention, making it possible to provide the detergency capacity required for the marine lubricant, the content of metallic detergent additives as defined above, undesirable with regard to the ash that they generate, can be reduced, while retaining good detergency properties.

[0121] According to a particular embodiment, the marine lubricating composition according to the invention may comprise less than 25% by mass, in particular from 0.1 to 25% by mass, more particularly from 5% to 15% by mass, of metallic detergent additive(s) distinct from the spiro compounds according to the invention, relative to the total mass of said composition.

[0122] According to a particular embodiment, the lubricating composition according to the invention may comprise less than 15% by mass, in particular less than 10% by mass and more particularly from 0.1 to 10% by mass, in particular from 0.5% to 5% by mass, of metallic detergent additive(s) distinct from the spiro compounds according to the invention, relative to the total mass of said composition.

[0123] In particular, said metallic detergent additive(s) may be present in the lubricating composition so as to provide a content of metallic element(s), in particular calcium, of less than or equal to 10,000 ppm, in particular ranging from 100 ppm to 10,000 ppm, preferably from 250 ppm to 6,000 ppm.

[0124] According to a particular embodiment, a marine lubricant according to the invention may comprise: - from 60 to 98.9% by mass, in particular from 65 to 98% by mass, of one or more base oils; - from 0.1 to 20% by mass, in particular from 0.2 to 15% by mass and more particularly from 0.5 to 10% by mass of at least one spiro compound according to the invention, as defined above, - optionally from 1 to 30% by mass, in particular from 5 to 25% by mass, of one or more metallic detergent additives, distinct from said spiro compound according to the invention, in particular chosen from overbased and neutral metallic detergents as defined above, in particular based on calcium or magnesium; the contents being expressed in relation to the total mass of said marine lubricant.

[0125] Furthermore, according to a particular embodiment, a lubricating composition according to the invention does not comprise a fatty amine, in particular of the tri-amine or tetra-amine type. Other additives

[0126] 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.

[0127] 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.

[0128] Basic organic additives improving TBN are known to those skilled in the art.

[0129] They may in particular be organic amino, alkyl or aromatic additives or even nitrogenous dispersants.

[0130] 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.

[0131] A lubricating composition considered 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; succinimides and their derivatives, in particular from polyisobutylene succinimide (PIBSI) or polyisobutylene succinic anhydride (PIBSA).

[0132] In particular, a lubricating composition considered 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.

[0133] A lubricating composition considered according to the invention may also comprise a viscosity index (VI) improver. Viscosity index (VI) improvers, in particular viscosity index improving polymers, make it possible to guarantee good cold resistance and minimal viscosity at high temperature. Examples of viscosity index improving polymers include polymer esters, homopolymers or copolymers, hydrogenated or non-hydrogenated, of styrene, butadiene and isoprene, homopolymers or copolymers of olefin, such as ethylene or propylene, polyacrylates and polymethacrylates. (PMA).

[0134] In particular, the viscosity index improving additive(s) may be present in a lubricating composition according to the invention in a content ranging from 1 to 15% by mass, in particular from 2 to 10% by mass, relative to the total mass of the lubricating composition.

[0135] A lubricating composition according to the invention may comprise at least one anti-wear and / or extreme pressure additive. The anti-wear additives protect the friction surfaces by forming a protective film adsorbed on these surfaces.

[0136] There is a wide variety of anti-wear additives. Preferably for the lubricating composition according to the invention, the anti-wear additives are chosen from phospho-sulfur additives such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates or ZnDTP. The preferred compounds are of formula Zn((SP(S)(OR3)(OR4))2, in which R3 and R4, identical or different, independently represent an alkyl group, preferably an alkyl group comprising from 1 to 18 carbon atoms.

[0137] Amine phosphates, polysulfides, in particular sulfur-containing olefins, are also anti-wear additives which can be used in the lubricating composition according to the invention.

[0138] 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.

[0139] A lubricating composition considered 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.

[0140] Among the commonly used antioxidant additives, mention may be made of phenolic type antioxidant additives, amine type antioxidant additives, phosphosulfur antioxidant additives. Some of these antioxidant additives, for example phosphosulfur antioxidant additives, may be ash-generating. The phenolic antioxidant additives may be ash-free or 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.

[0141] 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.

[0142] 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 NR5R6R7 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.

[0143] Sulfurized alkyl phenols or their alkali and alkaline earth metal salts can also be used as antioxidant additives.

[0144] A lubricating composition considered according to the invention may contain all types of antioxidant additives known to those skilled in the art.

[0145] 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.

[0146] As indicated previously, the spiro compound according to the invention makes it possible to provide the marine lubricant with excellent oxidation stability.

[0147] Thus, the present invention also relates to the use of at least one spiro compound of formula (I) as defined according to the present invention, as an additive in a lubricating composition intended for a marine engine, to improve the oxidation stability of said lubricating composition.

[0148] Therefore, a marine lubricant according to the invention may advantageously comprise a content of antioxidant additive(s) less than or equal to 10% by mass, in particular less than or equal to 5% by mass, in particular ranging from 0.1 to 2% by mass, relative to the total mass of said lubricant, or even be totally free of other antioxidant additive.

[0149] A lubricating composition considered according to the invention may also comprise at least one dispersing agent. The dispersing agents ensure the suspension and removal of insoluble solid contaminants consisting of secondary oxidation products which form when the lubricating composition is in service or of combustion residues, unburned materials, or any other contaminant. They may be chosen from Mannich bases, succinimides and their derivatives.

[0150] 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.

[0151] As mentioned above, all of the additives detailed above may be introduced in the form of a mixture or "package" of additives.

[0152] According to this embodiment, the additive package may represent from 1% to 35% by mass, in particular from 2 to 30% by mass, relative to the total mass of the composition, preferably ranging from 5% to 25% by mass.

[0153] According to a particular embodiment, a lubricating composition for a marine engine according to the invention may comprise, or even consist of: - a base oil or a mixture of base oils; - one or more spiro compounds according to the invention, in particular as defined above; - optionally one or more additives, distinct from said spiro compound(s), chosen from: other detergent additives, in particular overbased and neutral metallic detergent additives; anti-wear additives; basic organic additives improving the total base number; dispersant additives; viscosity index (VI) improvers, thickeners; anti-foaming agents; antioxidant additives; anti-rust additives; and mixtures thereof.

[0154] Preferably, a lubricating composition for a marine engine according to the invention comprises, or even consists of: - from 60 to 98.9% by mass, in particular from 70 to 90% by mass, of one or more base oils; - from 0.1 to 20% by mass, preferably from 0.5 to 10% by mass, of one or more spiro compounds according to the invention, in particular as defined above; - from 1% to 35% by mass, preferably from 5% to 25% by mass, of one or more additive(s) chosen from: other detergent additives, in particular chosen from overbased and neutral metallic detergent additives; basic organic additives improving the total base number; anti-wear additives; dispersant additives; viscosity index (VI) improvers; thickeners; anti-foaming agents; antioxidant additives; anti-rust additives; and mixtures thereof; the contents being expressed relative to the total mass of said lubricating composition.

[0155] In particular, a lubricating composition for a marine engine according to the invention may comprise, or even consist of: - from 60 to 97.9% by mass, in particular from 70 to 90% by mass, of one or more base oils; - from 0.1 to 20% by mass, preferably from 0.5 to 10% by mass, of spiro compound(s) according to the invention, in particular as defined above; - from 1 to 30% by mass, in particular from 5% to 25% by mass, of one or more metallic detergent additives distinct from said spiro compound(s), in particular chosen from overbased and neutral metallic detergents as defined above, in particular based on calcium or magnesium; and - optionally from 1% to 30% by mass, in particular from 3% to 20% by mass, of one or more other additives chosen from: basic organic additives improving the total base number; anti-wear additives; dispersant additives; viscosity index (VI) improvers; thickeners; anti-foaming agents; antioxidant additives; anti-rust additives; and mixtures thereof; the contents being expressed relative to the total mass of said lubricating composition. APPLICATION

[0156] As indicated above, a lubricating composition according to the invention is suitable for the lubrication of four-stroke or two-stroke engines.

[0157] The invention thus relates, according to another of its aspects, to the use of a composition as defined previously, incorporating one or more spiro compounds as detergent additive, for lubricating a marine engine.

[0158] Its good thermal resistance and oxidation stability properties make it particularly suitable as a cylinder oil, in other words for the lubrication of at least the piston-ring-liner area of ​​a marine engine and / or as a system oil, for the lubrication of the moving parts of the engine outside the piston-ring-liner assembly.

[0159] It can be implemented for slow, semi-fast or fast marine engines.

[0160] It can be implemented in particular for marine diesel engines.

[0161] It can also be implemented for marine engines whose fuel is obtained at least partially from organic matter, or biofuel, such as biodiesel, bioethanol or even ammonia.

[0162] All of the characteristics and particular modes relating to the spiro compound of formula (I) and to the lubricating composition comprising it also apply to the uses, processes and methods targeted according to the invention.

[0163] The invention will now be described by means of the following examples, given for illustrative and non-limiting purposes of the invention. Examples

[0164] Example 1: Preparation of lubricating compositions

[0165] Different lubricating compositions have been prepared from the following compounds: - lubricating base oil 1: group I mineral oil, with a viscosity at 40°C of 120 mm2 / s measured according to standard ASTM D7279; - lubricating base oil 2: group I mineral oil, with a viscosity at 40°C of 500 mm2 / s measured according to standard ASTM D7279; - additive package comprising a neutral phenate type metallic detergent additive (sulfurized calcium phenate of BN equal to 116 mg KOH / g of phenate); a calcium carbonate overbased sulfonate type metallic detergent additive (BN equal to 400 mg KOH / g of overbased sulfonate) and a silicon-based antifoaming agent; - a spiroboronate compound according to the invention (spiro compound of formula (I) according to the invention in which M is a Boron atom, R each represents a C16 alkyl group and n1 and n2 are 1).

[0166] The components and their quantities (expressed as a percentage by mass relative to the total mass of the composition) for the different lubricants are indicated in the following table. The lubricants are formulated by simple mixing at 60°C of the different components.

[0167] [Tables2] CCI H 12 Base oil 1 57.97 55.13 64.13 Base oil 2 33.00 33.00 33.00 Neutral phenate 7.00 7.00 - Overbased sulfonate CaCOs 2.00 2.00 - Antifoaming agent 0.03 0.03 0.03 Spiroboronate of the invention - 2.84 2.84

[0168] Lubricants are characterized by their total base number, noted TBN, expressed in mg KOH / g and evaluated according to standard ASTM D-2896.

[0169] [Tables3] CCI II 12 TBN lubricant in mg KOH / g 17 17 0 Example 2

[0170] Evaluation of the thermal resistance properties of lubricants Continuous ECBT test

[0171] The thermal resistance of the lubricants prepared in Example 1 was evaluated by implementing the continuous ECBT test. This test makes it possible to simulate both the thermal stability and the detergency of marine lubricants when the lubricating composition from the crankcase is sprayed onto the hot part of a marine engine and, in particular, at the top of the piston.

[0172] 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 MARCH 2000. ECBT Stop & Go Trial

[0173] The same type of test, as described above for the continuous ECBT test, is carried out under cycling conditions.

[0174] This test reflects the behavior of the lubricant in the piston ring belt area.

[0175] The tested products are projected into the beaker according to cyclic sequences during which the duration of the stop step is three times greater than the duration of the start step. The test temperatures are chosen between 270°C and 310°C, and the duration of the test is one hour. At the end of a cycle, the cooling of the beaker occurs naturally, without splashing, which contributes greatly 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.

[0176] The method is as follows: A video rating based on both the color of the varnish and the surface coverage rate is carried out. The rating is done on a scale of 0 to 100 points. Curves reporting the performance of each composition for at least three temperatures are plotted on a graph. When the curve crosses the 50 level of the performance index on a merit scale of 100, the corresponding temperature is noted. Results

[0177] The results obtained for each of the lubricants are gathered in the following table. Results of the continuous ECBT trial

[0178] [Tables4] CCI II 12 ECBT continuous lubricant (mg) 343 370 70

[0179] These results show that the replacement of metallic detergents by a spiro-boronate according to the invention leads to an improvement in the thermal resistance of the lubricant in the high temperature conditions encountered in the hot part of the engine.

[0180] Lubricants incorporating a spiroboronate compound according to the invention, as a total or partial replacement for metallic detergent additives, thus form fewer carbon deposits under the conditions of use in a marine engine, in other words have improved detergency properties, and thus make it possible to improve the cleanliness of the engine. ECBT Stop & Go Trial Results

[0181] [Tables5] CCI II 12 Lubricant Temperature (in °C)C> 284 294 304 corresponding to level 50 of the performance index on a merit scale of 100

[0182] These results show that the use, in a marine lubricant, of a spiroboronate compound according to the invention, in addition to metallic detergent additives, or even as a replacement for metallic detergent additives, makes it possible to improve the thermal stability of the lubricant under conditions which reflect those used at the level of the piston ring belt of a marine engine, and therefore the detergency properties. Example 3

[0183] Evaluation of the oxidation stability properties of lubricants

[0184] Oxidation stability is assessed by differential pressure scanning calorimetry, which determines the oxidation induction time, or OIT, for lubricating compositions. This is a standard procedure in the lubricating oil industry based on CEC L-85 T-99.

[0185] According to this protocol, the lubricant composition to be tested is heated to an elevated temperature, generally about 25°C below the average decomposition temperature for the sample being tested (in this case, 50 to 210°C), and the time at which the lubricant begins to decompose is measured. The longer the test duration, expressed in minutes, the better the oxidation stability of the lubricant. Results

[0186] The results obtained for each of the lubricants are gathered in the following table.

[0187] [Tableauxô] CCI II Lubricant Oxidation induction time (in min) 97 >250

[0188] These results show that the addition of a spiroboronate compound according to the invention makes it possible to significantly improve the oxidation stability of the lubricant.

Claims

1.

2.

3.

4.

5.

6. Claims Use, as a detergent additive in a lubricating composition intended for a marine engine, of at least one spiro compound of the following formula (I): in which M is an atom chosen from boron and aluminum; ni and n2 are, independently of each other, 0, 1 or 2; and R represent, independently of one another, a hydrocarbon group comprising from 1 to 50 carbon atoms, in particular from 5 to 20 carbon atoms. Use according to the preceding claim, said spiro compound being of formula (I) in which the substituents R represent, independently of one another, an aliphatic chain, linear or branched, in particular an alkyl chain, preferably linear, from C1 to C50; in particular from C3 to C30, in particular from C5 to C23 and more particularly from C8 to C20, more preferably from C16. Use according to claim 1 or 2, said spiro compound being of formula (I) in which n1 and n2 are 1, the R groups being identical. Use according to any one of the preceding claims, said spiro compound being of formula (I) in which M is a boron atom. Use according to any one of the preceding claims, said spiro compound(s) being used in a content of between 0.1 and 20% by mass relative to the total mass of said lubricating composition, preferably between 0.2 and 15% by mass, more preferably between 0.5 and 10% by mass, and more particularly from 0.5 to 5% by mass. Use according to any one of the preceding claims, said lubricating composition comprising at least one metallic detergent additive, distinct from the spiro compound of formula (I), in particular less than one overbased metallic detergent additive and / or one neutral metallic detergent additive, in particular calcium-based.

7. Use according to any one of the preceding claims, said composition comprising one or more base oils in a content of at least 50% by mass, relative to its total mass, in particular at least 60% by mass, more particularly ranging from 65 to 99% by mass and preferably from 70 to 98% by mass.

8. Use according to any one of the preceding claims, said composition comprising one or more other additives, distinct from said spiro compound(s), chosen from: overbased and neutral metallic detergent additives, basic organic additives improving the total base number; anti-wear additives; dispersant additives; a viscosity index (VI) improver; thickeners; anti-foaming agents; antioxidant additives; anti-rust additives; and mixtures thereof.

9. Use according to any one of the preceding claims, said composition being of viscometric grade SAE-20, SAE-30, SAE-40, SAE-50 or SAE-60 according to the SAEJ300 classification.

10. Use according to any one of the preceding claims, said lubricating composition being a lubricant for a two-stroke or four-stroke engine, in particular a lubricant intended for the lubrication of the piston-ring-liner assembly of said marine engine.

11. Use of at least one spiro compound of formula (I) defined in any one of claims 1 to 5 as an additive in a lubricating composition intended for a marine engine, to improve the oxidation stability of said lubricating composition.

12. Lubricating composition for the lubrication of a marine engine, comprising at least: - one or more base oils; - at least one spiro compound of formula (I) defined in any one of claims 1 to 5; - optionally one or more additives, distinct from said spiro compound(s), chosen from: other detergent additives, in particular overbased and neutral metallic detergent additives; anti-wear additives; basic organic additives improving the total base number; dispersant additives; viscosity index (VI) improvers; thickeners; anti-foaming agents; antioxidant additives; anti-rust additives and mixtures thereof.

13. Lubricating composition according to the preceding claim, said composition being of viscometric grade SAE-20, SAE-30, SAE-40, SAE-50 or SAE-60 according to the SAEJ300 classification; and / or said lubricating composition being a lubricant for a two-stroke or four-stroke engine, in particular a lubricant intended for the lubrication of the piston-ring-liner assembly of said marine engine.

14. A method of lubricating a marine engine, in particular a two- or four-stroke marine engine, comprising a step of bringing at least one mechanical part of said marine engine, in particular at least part of the rings, piston and / or liner of said marine engine, into contact with a lubricating composition as defined according to claim 12 or 13.