EP2271731A2

EP2271731A2 - Marine lubricant

Info

Publication number: EP2271731A2
Application number: EP09731363A
Authority: EP
Inventors: Valérie Doyen; Chantal Herault
Original assignee: Total Raffinage Marketing SA
Current assignee: TotalEnergies Marketing Services SA
Priority date: 2008-03-20
Filing date: 2009-03-19
Publication date: 2011-01-12
Anticipated expiration: 2029-03-19
Also published as: BRPI0911796A2; FR2928934B1; RU2010138338A; WO2009125083A3; EP2271731B1; FR2928934A1; US20110077177A1; RU2496859C2; JP5522803B2; ES2744189T3; KR20100124782A; US9493722B2; WO2009125083A2; CN102015981A; JP2011515529A; BRPI0911796B1; KR101668782B1

Abstract

The present invention relates to a cylinder lubricant having a BN, determined according to the ASTM D-2896 standard, of greater than or equal to 40 milligrams of potassium hydroxide per gram of lubricant, comprising a lubricant base oil for a marine engine and at least one overbased detergent that is based on alkali or alkaline-earth metals, and which also contains an amount of 0.01% to 10% by weight relative to the total weight of the lubricant, of one or more compounds (A) chosen from esters of saturated fatty monoacids comprising at least 14 carbon atoms and of alcohols comprising at most 6 carbon atoms.

Description

MARINE LUBRICANT

Field.

The present invention relates to a two-cycle marine engine cylinder lubricant for use with both high sulfur and low sulfur fuel oils. It relates more particularly to a lubricant having sufficient neutralization capacity vis-à-vis the sulfuric acid formed during the combustion of high-sulfur fuel oil, while limiting the formation of deposits during the use of fuel oils. low sulfur content. Technological Background of the Invention

The marine oils used in slow-moving 2-stroke engines are of two types. The cylinder oils on the one hand, ensuring the lubrication of the cylinder piston assembly, and the system oils on the other hand, ensuring the lubrication of all moving parts out of the cylinder piston assembly. Within the cylinder piston assembly, the combustion residues containing acid gases are in contact with the lubricating oil.

Acid gases are formed from the combustion of fuel oils; they are in particular sulfur oxides (SO ₂ , SO ₃ ), which are then hydrolyzed during contact with the moisture present in the combustion gases and / or in the oil. This hydrolysis generates sulfurous acid (HSO ₃ ) or sulfuric acid (H ₂ SO ₄ ).

To preserve the surface of the liners and avoid excessive corrosive wear, these acids must be neutralized, which is usually done by reaction with the basic sites included in the lubricant.

The capacity of neutralization of an oil is measured by its BN or Base Number in English, characterizing its basicity. It is measured according to ASTM D-

2896 and is expressed in equivalent weight of potash per gram of oil or mg of

KOH / g. The BN is a standard criterion for adjusting the basicity of cylinder oils to the sulfur content of the fuel oil used, in order to neutralize all the sulfur contained in the fuel, and likely to be converted into sulfuric acid by combustion and hydrolysis.

Thus, the higher the sulfur content of a fuel oil, the higher the BN of a marine oil. Therefore, marine oils of BN ranging from 5 to 100 mg KOH / g are available on the market.

Environmental concerns have led in some areas, including coastal areas, to limit the sulfur content in fuel oils used on ships. For example, the MARPOL Annex 6 (Regulations for the Prevention of air pollution from ships) regulations of IMO (International Maritime Organization) entered into force in May 2005. It provides for a maximum sulfur content of 4.5% m / m of fuel oils. as well as the creation of controlled release zones in sulfur oxides, called SECAs (SOx Emission Control Areas). Vessels entering these areas shall use fuel with a maximum sulfur content of 1.5% m / m or other alternative treatment to limit SOx emissions to meet the specified values. The notation% m / m denotes the weight percentage of a compound relative to the total weight of fuel oil or lubricating composition in which it is included. Ships operating on trans-continental routes will then use several types of heavy fuel oil depending on local environmental constraints and this allows them to optimize their cost of operation.

Thus, most of the container-carrying vessels currently under construction provide for the implementation of several bunkers, for a high sulfur 'high seas' oil on the one hand and for a 'SECA' fuel with a lower sulfur content. or equal to 1.5% m / m on the other hand.

The switching between these two categories of fuel oil may require adaptation of the operating conditions of the engine, in particular the implementation of appropriate cylinder lubricants. Currently, in the presence of high sulfur fuel oil (3.5% m / m and above), marine lubricants with a BN of about 70 are used.

In the presence of a fuel with a low sulfur content (1.5% m / m and less), marine lubricants with a BN of about 40 are used.

In these two cases, then a sufficient neutralization capacity is reached because the concentration required in basic sites provided by the overbased detergents of the marine lubricant is reached, but it is necessary to change the lubricant at each change of type of fuel oil.

In addition, each of these lubricants has limitations of use resulting from the following observations: the use of a BN 70 cylinder lubricant in the presence of a low sulfur fuel oil (1.5% w / w and less) and at fixed lubrication rate, creates a large excess of basic sites (strong BN) and a risk of destabilization of unused overbased detergent micelles, which contain insoluble metal salts. This destabilization results in the formation of insoluble metal salt deposits (eg calcium carbonate), mainly on the piston crown, and eventually can lead to a risk of excessive wear of polishing shirt. As a result, the optimization of the cylinder lubrication of a slow 2-stroke engine then requires the selection of the lubricant with the BN adapted to the fuel oil and to the operating conditions of the engine. This optimization reduces the operating flexibility of the engine and requires a high degree of technical skill of the crew in defining the conditions under which the changeover from one type of lubricant to the other must be achieved.

In order to simplify the maneuvers, it would therefore be desirable to have a single two-stroke marine engine cylinder lubricant that can be used with both high-sulfur fuel oils and low sulfur fuel oils.

Summary of the invention. The object of the present invention is to provide a lubricating oil that can ensure good lubrication of the marine engine cylinder and can withstand the stresses of high sulfur fuel oils and the stresses of low sulfur fuel oils.

To this end, the present invention provides a cylinder lubricant having a BN determined according to ASTM D-2896 greater than or equal to 40 milligrams of potash per gram of lubricant, comprising a marine engine lubricating base stock and at least one overbased detergent. based on alkali or alkaline earth metals, characterized in that it additionally contains an amount of from 0.01% to 10%, preferably from 0.1% to 2% by weight, relative to the total weight of the lubricant, one or more compounds (A) chosen from esters, preferably mono and di-esters, of saturated mono fatty acids containing at least 14 carbon atoms, and alcohols containing at most 6 carbon atoms.

Surprisingly, the Applicant has found that the introduction of certain types of surfactant compounds in a conventional cylinder lubricant formulation having a determined BN, leads to greatly increase the efficiency of said conventional lubricant vis-à-vis the neutralization of the lubricant. sulfuric acid formed during the combustion of any type of fuel whose sulfur content is less than 4.5% in a marine engine 2-stroke. The improvement in performance is particularly related to the rate or kinetics of neutralization of the sulfuric acid formed which is substantially increased.

This performance differential, between a conventional reference lubricant and the same surfactant additive lubricant, is characterized by a neutralization efficiency index measured using the enthalpy test described in the examples below.

In addition, the Applicant has found that the introduction of these surfactant compounds has no effect, or has a negligible effect on the initial BN value of said lubricant measured by ASTM D-2896. Indeed, the Applicant has found that the BN does not appear to be the sole criterion for the adaptability of the lubricant to the sulfur content of the fuel used. Although giving an indication of the potential for neutralization, the BN is not necessarily representative of the availability and accessibility of the basic sites constituting the BN vis-à-vis the acid molecules to be neutralized.

Thus, without wishing to be bound by any theory, it can be envisaged that these surface-active compounds do not in themselves bring additional basicity to the lubricant in which they are dissolved. On the other hand, their hydrophilic / lipophilic balance (HLB) leads, when they are introduced into a lubricant with a given BN, to make the basic sites contained in the overbased detergents of the lubricant more accessible, and thus to make the reaction of the lubricant more efficient. neutralization of the sulfuric acid formed during the combustion of the fuel oil.

This makes it possible to formulate a 2-stroke marine engine cylinder lubricant suitable for both high sulfur and low sulfur fuel oils.

Preferably, the present invention provides a cylinder lubricant having a determined BN in the range of 40 to 70 milligrams of potash per gram of lubricant, preferably 45 to 60, preferably 50 to 58.

According to one embodiment, the BN of the lubricants according to the present invention is between 47 and 53, preferably equal to 50.

According to another embodiment, the BN of the lubricants according to the present invention is between 54 and 56, preferably equal to 55.

Alternatively, the BN of the lubricants according to the present invention may be between 55 and 59, preferably between 56 and 58, preferably equal to 57. According to one embodiment, the compounds (A) are chosen from mono and di esters. mono saturated fatty acids having at least 14 carbon atoms, and alcohols having at most 6 carbon atoms.

Preferably, the compounds (A) are saturated fatty acid esters chosen from myristic, pentadecyl, palmitic, margaric, stearic, nonadecylic, arachidic, heneicosanoic and behenic acids.

Preferably, the compounds (A) are esters of alcohols chosen from ethanol, methanol, propanol, butanol, ethylene glycol, neopentyl glycol, glycerol, pentaerythritol, hexanediol and triethylene glycol.

Esters of myristic, pentadecyl, palmitic, margaric, stearic, arachidic, behenic heneicosanoic and ethanol, methanol, propanol, butanol, ethyleneglycol, neopentyl glycol, glycerol, pentaerythritol, hexanediol, triethylene glycol, especially mono and diesters.

According to one embodiment, the cylinder lubricant comprises one or more functional additives chosen from dispersing additives, anti-wear agents, anti-foam additives, anti-oxidant and / or anti-rust additives.

According to one embodiment, the cylinder lubricant comprises at least one overbased detergent selected from the group consisting of carboxylates, sulfonates, salicylates, naphthenates, phenates, and mixed overbased detergents associating at least two of these types of detergents, especially lubricant. cylinder comprises at least 10% of one or more overbased detergent compounds.

According to one embodiment, the overbased detergents are compounds based on metals chosen from the group consisting of calcium, magnesium, sodium or barium, preferentially calcium or magnesium.

In one embodiment the detergents are overbased with metal insoluble salts selected from the group of alkali metal and alkaline earth metal carbonates, hydroxides, oxalates, acetates, glutamates. Preferably, the overbased detergents are alkali or alkaline earth metal carbonates or at least one of the detergents is overbased with calcium carbonate.

In another embodiment, the cylinder lubricant comprises at least 0.1% of a dispersant additive selected from the family of succinimide PIBs.

According to another object, the invention relates to the use of a lubricant as described above as a single cylinder lubricant that can be used with any type of fuel oil whose sulfur content is less than 4.5%, preferably of which the Sulfur content is 0.5 to 4.5% w / w. Preferably, the single-cylinder lubricant can be used both with fuel oils with a sulfur content of less than 1.5% w / w and with fuel oils with a sulfur content of greater than 2.5% w / w, preferably greater than 3% w / w. % m / m.

Preferably, the single-cylinder lubricant can be used both with fuel oil with a sulfur content of less than 1% w / w and with fuel oils with a sulfur content of greater than 2.5% w / w, preferably greater than 3% w / w. / m.

According to another object the invention relates to the use of a lubricant as described above to prevent corrosion and / or reduce the formation of deposit insoluble metal salts in two-stroke marine engines during the combustion of any type of fuel oil with a sulfur content of less than 4.5% m / m. According to another object, the invention relates to the use of one or more compounds chosen from saturated mono-fatty acid esters comprising at least 14 carbon atoms, and alcohols containing at most 6 carbon atoms, such as surfactants in a cylinder lubricant having a BN, as measured by ASTM D-2896, greater than or equal to 40 milligrams of potash per gram of lubricant, to improve the effectiveness of said cylinder lubricant with respect to the neutralization rate sulfuric acid formed during the combustion of any type of fuel whose sulfur content is less than 4.5% m / m in a two-stroke marine engine.

Preferably, the surfactant is present in an amount of from 0.01% to 10% by weight, preferably from 0.1% to 2% by weight relative to the total weight of the lubricant. According to another object the invention relates to a method of manufacturing a lubricant as described above wherein the compound (A) is added as a separate component of the cylinder lubricant having a BN determined according to ASTM D- 2896 greater than or equal to 40 milligrams of potash per gram of lubricant and optionally comprising one or more functional additives. According to one embodiment, the lubricant is prepared by diluting a marine lubricant additive concentrate in which the compound (A) is incorporated.

According to another object the invention relates to an additive concentrate, for a cylinder lubricant having a BN determined according to ASTM D-2896 greater than or equal to 40 milligrams of potassium per gram of lubricant, said concentrate comprising 0.05 % to 30%, preferably from 0.5% to 25%, by weight relative to the total weight of the additive concentrate, of one or more compounds (A) chosen from saturated fatty acid monoethyl esters containing at least 14 carbon atoms, and alcohols having at most 6 carbon atoms.

According to another embodiment, the additive concentrate comprises from 15% to 80% by weight relative to the total weight of the additive concentrate, of one or more compounds (A) chosen from mono and di mono esters. saturated fatty acids having at least 14 carbon atoms, and alcohols having not more than 6 carbon atoms.

Preferably, in the additive concentrates according to the invention, the esters are monoesters or diesters of saturated fatty acids having at least 14 carbon atoms and alcohols containing at most 6 carbon atoms.

Preferably, the compounds (A) of the additive concentrates according to the invention are saturated fatty acid esters chosen from myristic, pentadecyl, palmitic, margaric, stearic, nonadecyl, arachidic, henicosanoic and behenic acids.

Preferably, the compounds (A) of the additive concentrates according to the invention are esters of alcohols chosen from ethanol, methanol, propanol and butanol. Ethylene glycol, neopentyl glycol, glycerol, pentaerythritol, hexanediol, triethylene glycol.

In the additive concentrates according to the invention, preference will be given to the esters of myristic, pentadecyl, palmitic, margaric, stearic, arachidic nonadecylic, behenic heneicosanoic and ethanol, methanol, propanol, butanol and ethylene glycol acids. , neopentyl glycol, glycerol, pentaerythritol, hexanediol, triethylene glycol, in particular the mono and diesters of the acids and alcohols mentioned above.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION Esters as surfactants:

Surfactants are molecules having on the one hand a lipophilic (or hydrophobic) chain, and on the other hand a hydrophilic group (or polar head).

The esters used in the invention are nonionic surfactants whose hydrophilic polar head is represented by the unit formed by the ester groups and any non-esterified hydroxyl groups, which must therefore be sufficiently close to one another to constitute such a " polar head ".

Thus, in the esters according to the invention, the ester functions are in limited number, preferably one or two, and are preferably at most distant from each other of four carbon atoms counted on the oxygen side of the ester function.

The non-esterified hydroxyl groups are also limited in number, preferably not more than four, and located in beta or gamma with respect to the oxygen of the COO group of the ester function (s).

The lipophilic portion is represented by one or more, preferably not more than two carbon chains derived from fatty acids, which must therefore contain enough carbon atoms to confer a sufficient lipophilic character to the molecule and preferably be free of polar grouping. and unsaturation.

In the invention, the esters are used alone or as a mixture and are chosen from saturated mono-fatty acid esters containing at least 14 carbon atoms, and alcohols containing at most 6 carbon atoms, preferably chosen from mono and diesters.

Moreover, the aliphatic chain of saturated fatty acids preferably comprises from 14 to 22 carbon atoms, preferably from 18 to 20 carbon atoms. The aliphatic chain of these fatty acids is preferably linear, optionally substituted, preferably with methyl, ethyl or propyl groups. These acids are, for example, and preferably chosen from myristic, pentadecyl, palmitic, margaric, stearic, nonadecyl, arachidic, heneicosanoic and behenic acids.

The alcohols of the esters according to the invention contain at most 6 carbon atoms. They are mono or polyalcohols, linear or branched. Preferably, they are at most tetraalcools. These alcohols are preferably chosen from ethanol, methanol, propanol, butanol, ethylene glycol, neopentyl glycol, glycerol, pentaerythritol, hexanediol and triethylene glycol.

Esters of myristic, pentadecyl, palmitic, margaric, stearic, arachidic, behenic henicosanoic and ethanol, methanol, propanol, butanol, ethylene glycol, neopentylglycol, glycerol, pentaerythritol, and the like are preferred. hexanediol, triethylene glycol, in particular mono and diesters.

Among the preferred esters, mention may be made, for example, of methyl esters of stearic acid, glycerol monostearate, neopentyl glycol mono or diesters or ethylene glycol and margaric and stearic acids.

Due to their low surfactant properties or strong lipophilic character, these compounds are stabilized in solution in the oil matrix and tend to shift the chemical equilibria within the overbased detergents. As a result, the basic sites provided by the overbased detergents are more accessible, which makes the sulfuric acid neutralization reaction more effective by these basic sites provided by the overbased detergents.

Note also that these compounds do not in themselves add additional basicity to the lubricant in which they are dissolved. The amounts of surfactants used in the invention range from 0.01% to 10% by weight relative to the total weight of the lubricant.

As the viscosity or gelation level of the final lubricant may vary according to the nature of the ester (s) chosen, a quantity ranging from 0.1% to 2% by weight of one or more esters relative to one another will preferably be used. to the total weight of the lubricant. It will thus be possible to retain the final marine lubricant according to the invention, a viscosimetric grade conforming to the specifications of use.

BN lubricants according to the present invention.

The BN of the lubricants according to the present invention is provided by the overbased detergents based on alkaline or alkaline earth metals. The value of this BN measured according to ASTM D-2896 can vary from 5 to 100 mg KOH / g in marine lubricants. A lubricant of BN value fixed will be chosen according to the conditions of use of said lubricants and in particular according to the sulfur content of the fuel oil used and in combination with the cylinder lubricants.

The lubricants according to the present invention are suitable for use as a cylinder lubricant, irrespective of the sulfur content of the fuel oil used as fuel in the engine.

As a result, the two-cycle marine engine cylinder lubricants according to the invention have a BN greater than or equal to 40, preferably ranging from 40 to 70.

According to a preferred embodiment of the invention, the lubricant formulation has a BN level, measured according to ASTM D-2896, intermediate between the levels required for the sulfur content limits of currently used fuel oils, that is, that is to say a BN between 45 and 60, preferably 50 to 58, preferably equal to 57, or else 55.

Alternatively, the BN of the lubricants according to the present invention may be between 55 and 59, preferably between 56 and 58, preferably equal to 57. The lubricant formulations according to the invention include surfactants of the ester type as described above. high, allowing increased accessibility of basic sites provided by overbased detergents, so as to neutralize the acid at least as effective as conventional formulations of BN higher.

For example, a lubricating formulation according to the invention having a BN of 55, or 57 will have at least the same sulfuric acid neutralization efficiency as a traditional BN formulation of 70.

Conventional BN 55 or 57 oils thus reformulated according to the invention make it possible to correctly prevent corrosion problems when using fuel oils with a high sulfur content (of the order of 3% w / w or more). An oil according to the present invention also allows a reduction in the formation of insoluble metallic salt deposits providing overbasing (eg CaCO ₃ ) when using low sulfur fuel oils (1.5% w / w and less, for example less than 1%), this reduction is directly related to the lowering of the BN made possible in the present formulation configuration. Furthermore, the lubricants according to the present invention retain a sufficient detergency capacity when formulated both for use with low and high sulfur fuel oils, since their BN (and hence the amount of detergents present) can be set at an intermediate level between that required for both categories of fuel oil.

Preferably, the lubricants according to the present invention are not in the form of an emulsion or of an oil-in-water or water-in-oil microemulsion where the BN is essentially provided by compounds present in the aqueous phase.

Overbased detergents.

The overbased detergents used in the lubricating compositions according to the present invention are well known to those skilled in the art.

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

The detergents are preferably chosen from alkali metal or alkaline earth metal salts of carboxylic acids, sulphonates, salicylates and naphthenates, as well as the salts of phenates.

The alkaline and alkaline earth metals are preferably calcium, magnesium, sodium or barium.

These metal salts may contain the metal in an approximately stoichiometric amount or in excess (in an amount greater than the stoichiometric amount). In the latter case, we are dealing with so-called overbased detergents.

The excess metal providing the overbased detergent character is in the form of oil insoluble metal salts, for example carbonate, hydroxide, oxalate, acetate, glutamate, preferably carbonate.

In the same overbased detergent, the metals of these insoluble salts may be the same as those of the oil-soluble detergents or may be different. It is preferentially chosen from calcium, magnesium, sodium or barium.

The overbased detergents are thus in the form of micelles composed of insoluble metal salts maintained in suspension in the lubricating composition by the detergents in the form of oil-soluble metal salts. These micelles may contain one or more types of insoluble metal salts, stabilized by one or more detergent types.

Overbased detergents with a single type of detergent soluble metal salt will generally be named after the nature of the hydrophobic chain of the latter detergent. So, they. will be called phenate, salicylate, sulfonate, naphthenate depending on whether this detergent is respectively a phenate, salicylate, sulfonate, or naphthenate. The overbased 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.

For use in the lubricating compositions according to the present invention, the oil-soluble metal salts will preferably be phenates, sulphonates salicylates, and mixed detergents phenate-sulphonate and / or salicylates calcium, magnesium, sodium or barium.

According to a preferred embodiment of the present invention, the insoluble metal salt providing the overbased character is calcium carbonate. The overbased detergents used in the lubricating compositions according to the present invention will preferably be phenates, sulphonates, salicylates and mixed detergents phenates-sulphonates-salicylates, overbased with calcium carbonate.

According to one embodiment of the present invention, at least 10% of one or more overbased detergent compounds is used, providing basicity to the lubricant in an amount sufficient to neutralize the acids formed upon combustion.

The amount of overbased detergents is typically determined to reach the targeted BN.

Base oils. In general, the base oils used for the formulation of lubricants according to the present invention can be oils of mineral, synthetic or vegetable origin as well as their mixtures.

The mineral or synthetic oils generally used in the application belong to one of the classes defined in the API classification as summarized below:

The Group 1 mineral oils can be obtained by distillation of selected naphthenic or paraffinic crudes and purification of these distillates by processes such as solvent extraction, solvent or catalytic dewaxing, hydrotreating or hydrogenation.

The oils of Groups 2 and 3 are obtained by more severe purification methods, for example a combination among hydrotreatment, hydrocracking, hydrogenation and catalytic dewaxing.

Examples of Group 4 and 5 synthetic bases include polyalphaolefins, polybutenes, polyisobutenes, alkylbenzenes.

These base oils can be used alone or as a mixture. A mineral oil can be combined with a synthetic oil. The cylinder oils for 2-stroke marine diesel engines have a viscometric grade SAE-40 to SAE-60, generally preferably SAE-50 equivalent to a kinematic viscosity at 100 ° C of between 16.3 and 21.9 mm ² / s. According to the uses of the profession, it is preferred to formulate cylinder oils for 2-stroke marine diesel engines having a kinematic viscosity at 100 ° C of between 18 and 21.5, preferably between 19 and 21.5. This viscosity can be obtained by mixing additives and base oils, for example containing Group 1 mineral bases such as Neutral Solvent (for example 500NS or 600 NS) and Brightstock bases. Any other combination of mineral, synthetic or vegetable bases having, in admixture with the additives, a viscosity compatible with the grade SAE-50 may be used.

Typically, a conventional cylinder lubricant formulation for slow 2-cycle marine diesel engines is SAE 40 to SAE60, preferably SAE50 (SA37 J300) and includes at least 50% by weight of original lubricating base oil. mineral and / or synthetic, suitable for use in a marine engine, for example of API Group 1, that is to say obtained by distillation of selected crudes and purification of these distillates by processes such as solvent extraction , solvent or catalytic dewaxing, hydrotreatment or hydrogenation. Their Viscosity Index (VI) is between 80 and 120; their sulfur content is greater than 0.03% and their saturated content is less than 90%. Functional additives.

The lubricant formulation according to the present invention may also contain functional additives adapted to their use, for example dispersant additives, anti-wear, anti-foam additives, anti-oxidant and / or anti-rust additives. These are known to those skilled in the art. These additives are generally present at a content by weight of 0.1 to 5%. Dispersant additives.

Dispersants are well known additives used in the formulation of lubricating composition, especially for application in the marine field. Their primary role is to maintain in suspension the particles present initially or appearing in the lubricant composition during its use in the engine. They prevent their agglomeration by playing on steric hindrance. They can also have a synergistic effect on the neutralization.

The dispersants used as lubricant additives typically contain a polar group, associated with a relatively long hydrocarbon chain, generally containing from 50 to 400 carbon atoms. The polar group typically contains at least one nitrogen, oxygen or phosphorus element.

The compounds derived from succinic acid are dispersants particularly used as lubrication additives. In particular succinimides, obtained by condensation of succinic anhydrides and amines, succinic esters obtained by condensation of succinic anhydrides and alcohols or polyols.

These compounds can then be treated with various compounds including sulfur, oxygen, formaldehyde, carboxylic acids and compounds containing boron or zinc to produce, for example, borated succinimides or zinc-blocked succinimides.

Mannich bases, obtained by polycondensation of phenols substituted with alkyl groups, formaldehyde and primary or secondary amines, are also compounds used as dispersants in lubricants.

According to one embodiment of the present invention, at least 0.1% of a dispersing additive is used. It is possible to use a dispersant in the family of succinimide PIBs, for example borates or zinc-blocked.

Other functional additives.

The lubricant compositions according to the present invention may also optionally contain other additives. For example, antiwear additives may be chosen, for example from the family of zinc dithiophosphates, antioxidant / anti-rust additives, for example detergents. organo metal or thiadiazoles, and anti foam additives to counter the effect of detergents, which may be for example polar polymers such as polymethylsiloxanes, polyacrylates. According to the present invention, the compositions of the lubricants described refer to the compounds taken separately before mixing, it being understood that said compounds may or may not retain the same chemical form before and after mixing. Of Preferably, the lubricants according to the present invention obtained by mixing the compounds taken separately are not in the form of emulsion or microemulsion.

The surfactant compounds contained in the lubricants according to the present invention may in particular be incorporated in a lubricant as a separate additive, for example to increase the neutralization efficiency of a conventional lubricant formulation already known.

The surfactants according to the invention are in this case preferably included in a conventional cylinder lubricant formulation for slow 2-stroke marine diesel engines of grade SAE 40 to SAE60, preferably SAE50 (according to SAE classification J300).

This classic formulation includes:

At least 50% by weight of lubricating base oil of mineral and / or synthetic origin, suitable for use in a marine engine, for example of API Group 1, that is to say obtained by distillation of selected crude then purification of these distillates by methods such as solvent extraction, solvent or catalytic dewaxing, hydrotreatment or hydrogenation. Their Viscosity Index (VI) is between 80 and 120; their sulfur content is greater than 0.03% and their saturated content is less than 90% • at least 10% of one or more overbased detergent compounds, providing basicity to the lubricant in an amount sufficient to neutralize the acids formed during combustion, which may for example be chosen from detergents of sulphonate, phenate and salicylate type;

At least 0.1% of a dispersing additive which may, for example, be chosen from the family of succinimide PIBs, and whose primary role is to maintain in suspension the particles present initially or appearing in the lubricant composition during its use in the engine ; it also has a synergistic effect on the neutralization, and possibly antifoam, antioxidant, and / or anti-rust, and / or anti-wear agents such as those of the family of zinc dithiophosphates.

All mass percentages expressed are based on the total weight of the lubricant composition. Additive concentrates for marine lubricants.

The ester-type surfactants contained in the lubricants of the present invention may also be included in a marine lubricant additive concentrate. The marine cylinder lubricant additive concentrates generally consist of a mixture of the constituents described above, detergents, dispersants, other functional additives, pre-dilution base oil, in proportions which make it possible to obtain, after dilution in an oil base of the cylinder lubricants having a BN determined according to ASTM D-2896 greater than or equal to 40 milligrams of potash per gram of lubricant. This mixture generally contains, relative to the total weight of concentrate, a detergent content greater than 80%, preferably greater than 90%, a dispersant additive content of 2 to 15%, preferably 5 to 10%, a content of other functional additives from 0 to 5%, preferably from 0.1 to 1%. According to one object of the invention, the additive concentrate for marine lubricant comprises one or more surfactants of ester type in a proportion making it possible to obtain a quantity of surfactant in the lubricant cylinder according to the invention of 0.01% to 10%, preferably 0.1 to 2%.

Thus, the marine lubricant additive concentrate contains, relative to the total weight of the concentrate, preferably from 0.05% to 30%, preferably from 0.5% to 25% by weight, of one or more compounds (A). chosen from saturated mono-fatty acid esters comprising at least 14 carbon atoms and alcohols containing at most 6 carbon atoms.

According to one embodiment, the additive concentrate for cylinder lubricant contains from 0.05 to 80%, preferably from 0.5 to 50% or alternatively from 2% to 40% or even 6% to 30% or 10 to 20% by weight relative to the total weight of the additive concentrate, of one or more compounds (A) chosen from saturated mono-fatty acid esters comprising at least 14 carbon atoms and alcohols containing at most 6 carbon atoms. According to a particular embodiment, the additive concentrate contains from 15% to 80% by weight relative to the total weight of the additive concentrate, of one or more compounds (A) as defined above.

All these percentages are expressed by weight relative to the total weight of the concentrate which also contains base oil in a small amount, but sufficient to facilitate the use of said additive concentrate. Measuring the performance differential, between a conventional reference lubricant and a lubricant according to the invention.

This measurement is characterized by a neutralization efficiency index measured according to the enthalpic test method described precisely in the examples and in which the progress of the exothermic neutralization reaction is followed by the rise in the temperature observed when the lubricant containing the basic sites is put in the presence of sulfuric acid.

Of course, the present invention is not limited to the examples and to the embodiment described and shown, but it is capable of numerous variants accessible to those skilled in the art.

Examples:

Example 1: This example aims at describing the enthalpic test for measuring the neutralization efficiency of lubricants with respect to sulfuric acid

The availability or accessibility of the basic sites included in a lubricant, in particular lubricant cylinder for marine engine two times, vis-à-vis the acid molecules, can be quantified by a dynamic test of speed monitoring or kinetics of neutralization.

Principle:

The acid-base neutralization reactions are generally exothermic and it is therefore possible to measure the heat release obtained by reaction of sulfuric acid with the lubricants to be tested. This evolution is followed by the evolution of the temperature over time in an adiabatic reactor of the DEWAR type.

From these measurements, it is possible to calculate an index quantifying the effectiveness of an additive lubricant according to the present invention with respect to a lubricant taken as a reference.

This index is calculated relative to the reference oil to which is assigned the value of 100. This is the ratio between the reference neutralization reaction times (S _ref) and the measured sample (S _mes ):

Neutralization efficiency index = S _ref / S _mes x 100 The values of these neutralization reaction times, which are of the order of a few seconds, are determined from the acquisition curves of the increase in temperature. as a function of time during the neutralization reaction. (See curve figure 1).

The duration S is equal to the difference t _f -1 between the time at the end of reaction temperature and the time at the reaction start temperature.

Time t; the start temperature reaction corresponds to the first rise in temperature after initiation of ^agitation. The time t _f at the final reaction temperature is that from which the temperature signal remains stable for a duration greater than or equal to half the reaction time.

The lubricant is all the more effective as it leads to short periods of neutralization and therefore to a high index.

Equipment used :

The reactor and agitator geometries as well as the operating conditions were chosen so as to be in a chemical regime, where the effect of the diffusional stresses in the oil phase is negligible. Therefore in the configuration of the material used, the fluid height must be equal to the inside diameter of the reactor, and the stirring propeller must be positioned at about 1/3 of the height of the fluid.

The apparatus consists of a cylindrical adiabatic reactor of 300 ml, the inner diameter of which is 52 mm and the internal height 185 mm, of a stirring rod provided with a propeller with inclined blades, 22 mm in diameter; the diameter of the blades is between 0.3 and 0.5 times the diameter of the DEWAR, that is to say from 15.6 to 26 mm.

The position of the propeller is set at a distance of about 15 mm from the bottom of the reactor. The stirring system is driven by a variable speed motor of 10 to 5000 rpm and a temperature acquisition system as a function of time.

This system is suitable for measuring reaction times of the order of 5 to 20 seconds and the temperature rise measurement of a few tens of degrees from a temperature of about 20 ° C to 35 ° C preferably about 30 ° C. The position of the temperature acquisition system in the DEWAR is fixed.

The stirring system will be adjusted so that the reaction proceeds in a chemical regime: in the configuration of the present experiment, the speed of rotation is set at 2000 rpm, and the position of the system is fixed.

Furthermore, the chemical regime of the reaction is also dependent on the oil height introduced into the DEWAR, which must be equal to the diameter of the latter, and which corresponds in this experiment to a mass of about 86. g of the lubricant tested.

To test the BN 70 lubricants, the amount of acid corresponding to the neutralization of 55 BN points is introduced into the reactor. 4.13 g of 95% concentrated sulfuric acid and 85.6 g of lubricant to be tested are introduced into the reactor, for a BN 70 lubricant, for example, neutralized at 55 BN points. After placing the stirring system inside the reactor so that the acid and the lubricant mix well and repeatedly between two tests, stirring is started to follow the reaction in chemical regime . The acquisition system is permanent. Operation of the enthalpic test - calibration:

To calculate the efficiency indices of the lubricants according to the present invention by the method described above, we have chosen to take as a reference the neutralization reaction time measured for a two-stroke marine engine cylinder oil of BN 70 (measured by ASTM D-2896), having no surfactant additive according to the present invention.

This oil is obtained from a mineral base obtained by mixing a distillate of density at 15 ° C of between 880 and 900 Kg / m ³ with a distillation residue having a density of between 895 and 915 Kg / m. ³ (Brightstock) in a distillate / residue ratio of 3. To this base is added a concentrate in which there is a calcium sulfonate of BN equal to 400 mg KOH / g, a dispersant, a calcium phenate of BN equal to 250 mg KOH / g in the amount necessary to obtain a lubricant of BN 70 mg KOH / g.

The lubricant thus obtained has a viscosity at 100 ° C of between 18 and 20.5 mms.

The neutralization reaction time of this oil (hereinafter referred to as Href) is 10.3 seconds and its neutralization efficiency index is set to 100.

Two other lubricant samples of BN 55 and 40 are prepared from the same additive concentrate diluted respectively by 1.25 and 1.7 according to the desired BN and a lubricating base whose mixture of distillate and residue is adapted to obtain in the end a viscosity at 100 ° C of between 19 and 20.5 mm ² / s.

These two samples, hereinafter referenced H55 and H40 are also free of surfactant additive additives according to the present invention.

Table 1 below shows the values of the neutralization indices obtained for the BN 40 and 55 samples prepared by dilution of the additives included in the BN 70 reference oil.

Table 1

Example 2 This example describes the influence of the additives (compounds (A)) according to the invention for a constant BN formulation 55.

The reference is the cylinder oil for two-stroke marine engine BN 70, not additive according to the present invention, and referenced Href in the previous example.

The samples additive BN 55 to be tested are prepared from the non-additive lubricant referenced H 55 in the previous example.

These samples are obtained by mixing in a beaker, at a temperature of 60 ^° C., with stirring sufficient to homogenize the mixture of the lubricant H55 to be added and the selected ester-type surfactant. For a mixture of x% m / m content in surfactant:

x g of ester (compound (A)) is introduced

- It is completed to 100 g with the lubricant H55 additiver.

Table 2 below groups the values of the efficiency indices of the different samples thus prepared.

The BNs of the lubricants before and after introduction of the surfactants according to the present invention were also measured according to ASTM D-2896.

Table 2

It can be seen that the lubricants with additives according to the present invention (Nos. 3 to 7 and 11-12) have, at BN 55, a neutralization efficiency index higher than that of the same oil of BN 55 not thus additivated.

Almost all BN 55 oils additivated according to the present invention have a higher neutralization efficiency index than that of a non-additivated BN 70 oil taken as a reference.

It may also be noted that for the oils additive with esters outside the definition of the invention (ex 8-10), the neutralization efficiency indices are very little or not at all improved. The index values calculated for BN 55 oils according to the present invention are overall 12 to 25% higher than the reference, even though the introduction of the additives according to the present invention has little or no influence on the value of their BN.

Claims

1. A cylinder lubricant having a BN determined in accordance with ASTM D-2896 greater than or equal to 40 milligrams of potash per gram of lubricant, comprising a marine engine lubricating base stock and at least one alkali or alkaline base overbased detergent characterized in that it additionally contains an amount of from 0.01% to 10% by weight, relative to the total weight of the lubricant, of one or more compounds (A) chosen from saturated fatty acid monoethyl esters comprising at least 14 carbon atoms and alcohols having not more than 6 carbon atoms.

2. The cylinder lubricant according to claim 1 characterized in that the compounds (A) are chosen from monoesters and diesters.

3. cylinder lubricant according to one of the preceding claims, characterized in that the compound or compounds (A) are chosen from monoesters of monoalcohol.

4. cylinder lubricant according to claim 1 or 2, characterized in that the compound or compounds (A) are chosen from diesters, the ester functions being at most distant from each other by four carbon atoms counted on the oxygen side of the ester function.

5. The cylinder lubricant according to one of the preceding claims, characterized in that the compounds (A) have nonesterified hydroxyl groups, preferably not more than four, which are located in beta or gamma with respect to the COO group oxygen. of the ester function (s).

6. Cylinder lubricant according to any one of the preceding claims, characterized in that the fatty acids are chosen from myristic, pentadecyl, palmitic, margaric, stearic, nonadecylic, arachidic, heneicosanoic and behenic acids.

7. The cylinder lubricant as claimed in any one of the preceding claims, characterized in that the alcohols are chosen from ethanol, methanol, propanol, butanol, ethylene glycol, neopentyl glycol, glycerol, pentaerythritol and the like. hexanediol, triethylene glycol.

8. A cylinder lubricant according to any one of the preceding claims, comprising from 0.1% to 2% by weight of compounds (A) relative to the total weight of the lubricant.

9. A cylinder lubricant according to any one of the preceding claims having a BN determined according to ASTM D-2896 in the range of 40 to 70 milligrams of potash per gram of lubricant, preferably 45 to 60, preferably 50 at 58.

10. A cylinder lubricant according to any one of the preceding claims having a BN determined according to ASTM D-2896 in the range of 47 to 53 milligrams of potash per gram of lubricant, preferably 50.

A cylinder lubricant according to any one of claims 1 to 9, having a BN determined according to ASTM D-2896 in the range of 54 to

56 milligrams of potash per gram of lubricant, preferably 55.

A cylinder lubricant according to any one of claims 1 to 9 having a BN determined according to ASTM D-2896 in the range of 55 to 59 milligrams of potash per gram of lubricant, preferably 56 to 58, preferably equal to 57.

13. The lubricant cylinder according to one of the preceding claims, which comprises one or more functional additives selected from dispersant additives, anti-wear, anti-foam additives, anti-oxidant and / or anti-rust additives.

The cylinder lubricant according to one of the preceding claims, which comprises at least one overbased detergent selected from the group consisting of carboxylates, sulfonates, salicylates, naphthenates, phenates, and mixed overbased detergents associating at least two of these types of detergents. .

The cylinder lubricant according to one of the preceding claims, which comprises at least 10% of one or more overbased detergent compounds.

16. Lubricant according to any one of claims 14 or 15, wherein the overbased detergents are compounds based on metals selected from the group consisting of calcium, magnesium, sodium or barium, preferably calcium or magnesium.

17. Lubricant according to any one of claims 14 to 16, wherein the detergents are overbased by insoluble metal salts selected from the group of carbonates, hydroxides, oxalates, acetates, glutamates of alkali metals and alkaline earth.

18. Lubricant according to one of claims 14 to 17, wherein the overbased detergents are alkali or alkaline earth metal carbonates

19. Lubricant according to one of claims 14 to 18, wherein at least one of the detergents is overbased with calcium carbonate.

20. The cylinder lubricant according to one of the preceding claims, which comprises at least 0.1% of a dispersant additive selected from the succinimide PIB family.

21. Use of a lubricant according to any one of claims 1 to 20 as single cylinder lubricant for use with any type of fuel oil whose sulfur content is less than 4.5% m / m, preferably with sulfur content is from 0.5% to 4% m / m.

22. Use of a lubricant according to any one of claims 1 to 20 as a single cylinder lubricant for use with both fuel oils with a sulfur content of less than 1.5% m / m and with higher sulfur content fuel oils. at 3% m / m.

23. Use of a lubricant according to one of claims 1 to 20 to prevent corrosion and / or reduce the formation of deposition of insoluble metal salts in two-stroke marine engines during the combustion of any type of fuel oil whose content in sulfur is less than 4.5% w / w.

24. Use of one or more compounds selected from saturated mono-fatty acid esters having at least 14 carbon atoms and alcohols having not more than 6 carbon atoms as a surfactant in cylinder lubricants having a BN, as measured by the ASTM D-2896, greater than or equal to 40 milligrams of potash per gram of lubricant, to improve the effectiveness of said cylinder lubricant with respect to the rate of neutralization of the sulfuric acid formed during the combustion of any type of fuel with a sulfur content of less than 4.5% m / m, especially in a two-stroke marine engine.

25. Use according to the preceding claim, wherein the surfactant is present in an amount of 0.01% to 10% by weight, preferably 0.1% to 2% by weight relative to the total weight of the lubricant.

26. Use according to one of claims 21 to 25, wherein the cylinder lubricant has the characteristics as defined in any one of claims 1 to 20.

A method of manufacturing a lubricant according to any one of claims 1 to 20, wherein compound A is added as a separate component of the cylinder lubricant having a BN determined according to ASTM D-2896 greater than or equal to 40 milligrams of potash per gram of lubricant and optionally comprising one or more functional additives.

28. A method of manufacturing a lubricant according to any of claims 1 to 20 by diluting a marine lubricant additive concentrate in which compound A is incorporated.

29. Additive concentrate, for cylinder lubricant having a BN determined according to ASTM D-2896 greater than or equal to 40 milligrams of potash per gram of lubricant, said concentrate comprising from 0.05% to 30%, preferably from 0 to From 5% to 25%, by weight relative to the total weight of the additive concentrate, of one or more compounds (A) chosen from saturated fatty acid monoethyl esters containing at least 14 carbon atoms and alcohols comprising not more than 6 carbon atoms.

30. A cylinder lubricant additive concentrate having a BN determined according to ASTM D-2896 greater than or equal to 40 milligrams of potash per gram of lubricant, said concentrate comprising from 15% to 80% by weight relative to the total weight of the lubricant. additive concentrate, of one or more compounds (A) chosen from saturated mono-fatty acid esters comprising at least 14 carbon atoms and alcohols containing at most 6 carbon atoms.

31. An additive concentrate according to claim 29 or 30, wherein the compounds (A) are selected from monoesters and diesters.

32. An additive concentrate according to any one of claims 29 to 31, wherein the fatty acids are chosen from myristic, pentadecyl, palmitic, margaric, stearic, nonadecylic, arachidic, henicosanoic and behenic acids.

An additive concentrate according to any of claims 29 to 32 wherein the alcohols are selected from ethanol, methanol, propanol, butanol, ethylene glycol, neopentyl glycol, glycerol, pentaerythritol, hexanediol, triethylene glycol.