EP3212745B1 - Lubricant for marine engines - Google Patents

Description

The present invention is applicable to the field of lubricants, and more particularly to the field of lubricants for marine engines, in particular for two-stroke marine engines. More particularly, the present invention relates to a marine engine lubricant comprising at least one base oil and at least one fatty amine.

The lubricant according to the invention has a high reserve of basicity which results in a high BN (or Base Number in English) and can be used both with fuel oils with a high sulfur content and fuel oils with a low sulfur content. The lubricant according to the invention has sufficient neutralizing power with respect to the sulfuric acid formed during the combustion of fuel oils with a high sulfur content as well as a reduced or even non-existent risk of increasing its viscosity, while by limiting the formation of deposits at high temperature.

The lubricant according to the invention can also be characterized by a low BN value and therefore be usable with fuel oils with a very low sulfur content, while presenting a reduced or even non-existent risk of increasing its viscosity and limiting the formation of high temperature deposits.

The present invention also relates to a method for lubricating a marine engine, and more particularly a two-stroke marine engine using this lubricant.

The present invention also relates to a method for reducing the formation of deposits in the hot parts of a marine engine, in particular a two-stroke marine engine, comprising bringing said hot parts into contact with a lubricant comprising a fatty amine.

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

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

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

The neutralization capacity of an oil is measured by its BN, characterizing its basicity. It is measured according to the ASTM D-2896 standard and is expressed as the equivalent weight of potassium hydroxide per gram of oil or mg of KOH/g of oil. The BN is a classic criterion allowing the basicity of cylinder oils to be adjusted to the sulfur content of the fuel oil used, in order to be able to neutralize the sulfur contained in the fuel, and liable to be transformed 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 must be. This is why BN marine oils varying from 5 to 100 mg KOH/g of oil are available on the market. This basicity is provided by detergents which are overbased with insoluble metal salts, in particular metal carbonates. The usual overbased detergents intrinsically have a BN typically between 150 and 700 mg of potash per gram of detergent. Their mass content in the lubricant is determined according to the BN level to be achieved. A part of the BN can also be provided by non-overbased or “neutral” detergents with a BN typically less than 150 mg of potash per gram of detergent. However, it is not possible to produce formulas of cylinder lubricants for marine engines having a high BN, in particular for two-stroke marine engines, where all the BN is provided by "neutral" detergents: it would indeed be necessary to incorporate them in too large quantities, which could affect the effectiveness of the lubricant and would not be realistic from an economic point of view.

The insoluble metallic salts of overbased detergents, for example calcium carbonate, therefore contribute significantly to the BN of the usual lubricants.

The actual detergent portion, or soaps, found in both neutral and overbased detergents, typically provides the bulk of the BN complement. Environmental concerns have led, in certain areas and in particular in coastal areas, to requirements in terms of limiting the level of sulfur in the fuel oils used on ships.

Thus, the MARPOL Annex 6 regulation (Regulations for the Prevention of air pollution from ships) of the IMO (International Maritime Organisation) came into force in May 2005. It sets a maximum sulfur content of 4.5% by weight relative to the total weight of fuel oil for heavy fuel oils as well as the creation of zones with controlled emissions of sulfur oxides, called SECAs (SOx Emission Control Areas). By heavy fuel oils we mean high viscosity fuels mainly used by large diesel engines installed on board ships.

Thus, ships entering these areas must use fuel oils with a maximum sulfur content of 1.5% by weight relative to the total weight of the fuel oil or any other alternative treatment aimed at limiting SOx emissions in order to comply with the specified values. More recently amendments to the MARPOL Annex 6 regulations have been made. These amendments are summarized in the table below. Thus, the maximum sulfur content restrictions have become more severe with a limited worldwide maximum content of 4.5% by weight in relation to the total weight of fuel oil to 3.5% by weight in relation to the total weight of fuel oil. SECAs (Sulfur Emission Control Areas) have become ECAs (Emission Control Areas) with an additional reduction in the maximum allowable sulfur content from 1.5% by weight relative to the total weight of fuel oil to 1.0% by weight relative to the total weight fuel oil and the addition of new limits on NOx content and particulates. Amendments to MARPOL Annex 6 (Meeting MEPC n°57 - April 2008) Maximum sulfur content General limit Limit for ECA's 3.5% by weight relative to the total weight of fuel oil on 01/01/2012 1% by weight relative to the total weight of fuel oil on 07/01/2010 0.5% by weight relative to the total weight of fuel oil on 01/01/2020 0.1% by weight relative to the total weight of fuel oil on 01/01/2015

Ships on trans-continental routes use several types of heavy fuel oil according to local environmental constraints while allowing them to optimize their operating costs.

Thus many container ships use several bunker tanks, for fuel oil with a high sulfur content (at most 3.5% by weight of sulfur relative to the total weight of the fuel oil and more) or "deep sea" fuel oil on the one hand and for an 'ECA' fuel oil with a sulfur content less than or equal to 1% by weight relative to the total weight of the fuel oil on the other hand.

Switching between these two fuel oil categories may require the engine operating conditions to be adapted, in particular the use of suitable cylinder lubricants.

Currently, in the presence of fuel oil with a high sulfur content (3% by weight relative to the total weight of the fuel oil and more), marine lubricants having a BN of the order of 70 mg of KOH/mg of lubricant are mainly used.

In the presence of a fuel oil with a low sulfur content (1% by weight relative to the total weight of the fuel oil and less), marine lubricants with a BN of the order of 40 mg of KOH/mg of lubricant can be mainly recommended. .

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

In addition, each of these lubricants has limits of use for the following reasons: the use of a BN cylinder lubricant 70 mg of KOH/g of lubricant in the presence of a fuel oil with a low sulfur content (1% by weight relative to the total weight of fuel oil and less) and at a fixed lubrication rate, creates a significant excess of basic sites and a risk of destabilization of unused overbased detergent micelles, which contain insoluble metal salts. This destabilization can result in the formation of deposits of insoluble metallic salts (for example calcium carbonate) and having a high hardness, mainly on the piston crown, and in the long term can lead to a risk of excessive wear of the liner polishing type. As for the use of a BN cylinder lubricant with 40 mg of KOH/g of lubricant, such a BN does not provide sufficient neutralization capacity to the lubricant in the presence of a fuel with a high sulfur content and thus can lead to a high risk of corrosion.

Thus, the optimization of the cylinder lubrication of a two-stroke engine then requires the selection of a lubricant whose BN is adapted to the sulfur content of the fuel oil used and to the operating conditions of the engine. This optimization reduces the operating flexibility of the engine and requires significant technical skills from the crew in defining the conditions under which the change from one type of lubricant to another must be carried out.

Requirement WO2009/153453 describes the use of fatty amines in a marine lubricant for 2-stroke engines and suitable for use with high and low sulfur fuel oils.

However, the BN of the lubricant described in this document is limited and does not exceed 72.

US 3,814,212 relates to a lubricating composition comprising a polyamine having at least 12 carbon atoms. The lubricating composition can also include other additives such as mineral oil.

However, the lubricating composition described in this document is not a lubricating composition for a marine engine. Moreover, this composition does not include neutral and/or overbased detergents.

Furthermore, depending on the nature of the amine, a risk of formation of deposits at high temperature may appear, thus altering the effectiveness of the lubricant and the cleanliness of the engine.

Indeed, the operating temperature of marine engines, and in particular of 2-stroke marine engines, continues to increase. Thus, the lubricant, which is in direct contact with the engine, and in particular with the hot parts of the engine such as the ring/piston/liner (or SPC) area, must have increased resistance to temperature and thus minimize or even prevent the formation deposits in these hot parts.

Moreover, today there is a demand for low BN marine lubricants, in particular having a BN less than or equal to 40, intended for use in the presence of fuel oils with a very low sulfur content (sulphur content less than 0, 5%) and with increased thermal resistance.

Thus, it would therefore be desirable to have a marine lubricant, in particular for two-stroke marine engines, which can have a high BN, in particular close to or equal to 100 or a low BN, in particular close to or equal to 25, while with increased temperature resistance and therefore a low risk of deposit formation in the hot parts of the engine.

It would also be desirable to have a lubricant for a marine engine, in particular for a two-stroke marine engine, presenting no or very little risk of viscosity increase over time, and in particular during its use.

Description of the invention

One objective of the present invention is to provide a lubricating composition all or part of the aforementioned drawbacks.

Another objective of the present invention is to provide a lubricating composition which is resistant to aging and which retains its properties over time.

Another object of the invention is to provide a lubricating composition whose formulation is easy to implement.

Another object of the invention is to provide a lubricating composition that makes it possible to minimize, or even prevent the formation of deposits in the hot parts of a marine engine.

Another object of the present invention is to provide a method for lubricating a marine engine, and more particularly a two-stroke marine engine that can be used both with high sulfur content fuel oils and low sulfur content fuel oils. .

Another object of the present invention is to provide a method for lubricating a marine engine, and more particularly a two-stroke marine engine that can be used with fuel oils with a very low sulfur content.

Another object of the present invention is to provide a method for reducing the formation of deposits in the hot parts of a marine engine, and more particularly of a two-stroke marine engine.

• au moins une huile de base lubrifiante,
• de 0.1 à 15% en poids, par rapport au poids total de la composition lubrifiante, d'au moins une amine grasse de formule (I) :
  
          R₁R₂N-(CH₂)₃-[NH(CH₂)₃]_n-NH₂     (I)
  
  dans laquelle :
  • R₁ représente un groupement alkyle saturé linéaire ou ramifié, comprenant au moins 14 atomes de carbone,
  • R₂ représente un groupement alkyle saturé linéaire ou ramifié, comprenant au moins 14 atomes de carbone,
  • n représente 0, 1 ou 2,
  l'amine grasse ayant un BN déterminé selon la norme ASTM D-2896 allant de 150 à 350 milligrammes de potasse par gramme d'amine,
• au moins 3% en poids, par rapport au poids total de la composition lubrifiante, d'au moins un additif choisi parmi les détergents surbasés et/ou les détergents neutres,
  ladite composition lubrifiante ne comprenant pas d'amines grasses autres que l'amine grasse de formule (I).

The present invention therefore relates to a lubricating composition comprising:

• at least one lubricating base oil,
• from 0.1 to 15% by weight, relative to the total weight of the lubricating composition, of at least one fatty amine of formula (I):
  
  R ₁ R ₂ N-(CH ₂ ) ₃ -[NH(CH ₂ ) ₃ ] _n -NH ₂ (I)
  
  in which :
  • R ₁ represents a linear or branched saturated alkyl group, comprising at least 14 carbon atoms,
  • R ₂ represents a linear or branched saturated alkyl group, comprising at least 14 carbon atoms,
  • n represents 0, 1 or 2,
  the fatty amine having a BN determined according to the ASTM D-2896 standard ranging from 150 to 350 milligrams of potash per gram of amine,
• at least 3% by weight, relative to the total weight of the lubricating composition, of at least one additive chosen from overbased detergents and/or neutral detergents,
  said lubricating composition not comprising fatty amines other than the fatty amine of formula (I).

The applicant has found that it is possible to formulate lubricating compositions, in particular for marine engines, where a significant part of the BN is provided by fatty amines soluble in the lubricating base oil, while maintaining the same level of performance by compared to conventional formulations of equivalent or even higher BN.

The performances in question here are in particular the reduction in the formation of deposits, measured using the ECBT test described below, as well as the thermal resistance at high temperature, measured using the ATG and DSC tests as well. described below.

The lubricating composition according to the invention thus has such performances, while retaining a viscosity which makes it suitable for its use.

Thus, the present invention makes it possible to formulate high BN lubricating compositions for marine engines, in particular for two-stroke marine engines, usable both with fuel oils with a high sulfur content and fuel oils with a low sulfur content and allowing to have reduced risk of deposit formation while maintaining other performance of the lubricating composition.

Advantageously, the present invention also makes it possible to formulate low BN lubricating compositions for marine engines, in particular for two-stroke marine engines, usable with fuel oils with a very low sulfur content and allowing a reduced risk of deposit formation while now the other performance of the lubricating composition.

Advantageously, the lubricating compositions according to the invention have a good capacity for neutralizing sulfuric acid.

Advantageously, the lubricating compositions according to the invention have increased heat resistance, in particular at high temperature.

Advantageously, the lubricating compositions according to the invention retain good viscosity stability over time.

Advantageously, the lubricating compositions according to the invention present no or very little risk of thickening depending on the conditions of use.

The invention also relates to the use of a lubricating composition as defined above for lubricating a marine engine, in particular a two-stroke marine engine.

The invention also relates to the use of a lubricating composition as defined above as a single cylinder lubricant that can be used both with fuel oils with a sulfur content of less than 1% by weight relative to the total weight of the fuel oil, with fuel oils with a sulfur content ranging from 1 to 3.5% by weight relative to the total weight of the fuel oil and with fuel oils with a sulfur content greater than 3.5% by weight relative to the total weight of the fuel oil.

In one embodiment, the lubricating composition as defined above is used as a single cylinder lubricant that can be used both with fuel oils with a sulfur content of less than 1% by weight relative to the total weight of the fuel oil and with fuel oils with sulfur content ranging from 1 to 3.5% by weight relative to the total weight of fuel oil.

The invention also relates to the use of a lubricating composition as defined above as a cylinder lubricant that can be used with fuel oils with a sulfur content of less than 0.5% by weight relative to the total weight of the fuel oil.

The invention also relates to the use of a lubricating composition as defined above for reducing the formation of deposits in the hot parts of a marine engine, preferably in the segment-pistons-liner (SPC) zone. The invention also relates to a method for lubricating a marine engine, in particular a two-stroke marine engine comprising at least one step of bringing the engine into contact with a lubricating composition as defined above.

The invention also relates to a method for reducing the formation of deposits in the hot parts of a marine engine, in particular of a two-stroke marine engine comprising at least one step of bringing said hot parts of the engine into contact with a lubricating composition such as defined above.

• R₁ représente un groupement alkyle saturé linéaire ou ramifié, comprenant au moins 14 atomes de carbone,
• R₂ représente un groupement alkyle saturé linéaire ou ramifié, comprenant au moins 14 atomes de carbone,
• n représente 0, 1 ou 2,

l'amine grasse de formule (I) ayant un BN déterminé selon la norme ASTM D-2896 allant de 150 à 350 milligrammes de potasse par gramme d'amine.The invention also relates to the use of a fatty amine in a lubricating composition for reducing the formation of deposits in the hot parts of a marine engine, the fatty amine being a fatty amine of formula (I):

R ₁ R ₂ N-(CH ₂ ) ₃ -[NH(CH ₂ ) ₃ ] _n -NH ₂ (I)

in which :

• R ₁ represents a linear or branched saturated alkyl group, comprising at least 14 carbon atoms,
• R ₂ represents a linear or branched saturated alkyl group, comprising at least 14 carbon atoms,
• n represents 0, 1 or 2,

the fatty amine of formula (I) having a BN determined according to the ASTM D-2896 standard ranging from 150 to 350 milligrams of potash per gram of amine.

Detailed description of the invention

The percentages indicated below correspond to mass percentages of active material.

Fatty amines

• R₁représente un groupement alkyle saturé linéaire ou ramifié, comprenant au moins 14 atomes de carbone,
• R₂ représente un groupement alkyle saturé linéaire ou ramifié, comprenant au moins 14 atomes de carbone,
• n représente 0, 1 ou 2 ou 3,

l'amine grasse ayant un BN déterminé selon la norme ASTM D-2896 allant de 150 à 350 milligrammes de potasse par gramme d'amine.The lubricating composition according to the invention comprises from 0.1 to 15% by weight, relative to the total weight of the lubricating composition, of at least one fatty amine of formula (I):

R ₁ R ₂ N-(CH ₂ ) ₃ -[NH(CH ₂ ) ₃ ] _n -NH ₂ (I)

in which :

• R ₁ represents a linear or branched saturated alkyl group, comprising at least 14 carbon atoms,
• R ₂ represents a linear or branched saturated alkyl group, comprising at least 14 carbon atoms,
• n represents 0, 1 or 2 or 3,

the fatty amine having a BN determined according to the ASTM D-2896 standard ranging from 150 to 350 milligrams of potash per gram of amine.

R ₁ and R ₂ , which are identical or different, independently represent a linear or branched saturated alkyl group comprising at least 14 carbon atoms; which means that the fatty amine according to the invention does not comprise unsaturations. Thus the level of unsaturations in the fatty amine according to the invention is zero.

Fatty amines are obtained from saturated carboxylic acids.

The preferred starting fatty acids for obtaining fatty amines according to the invention can be derived from the hydrolysis of triglycerides present in vegetable and animal oils, such as coconut oil, palm oil, olive oil, peanut oil , rapeseed, sunflower, soy, cotton, flax, beef tallow, ....

Natural oils may have been genetically modified to enrich their content of certain fatty acids. By way of example, mention may be made of rapeseed oil or oleic sunflower oil.

In one embodiment, the fatty amines used in the lubricants according to the invention can be obtained from natural, vegetable or animal resources.

• R₁ représente un groupement alkyle saturé linéaire ou ramifié comprenant de 14 à 22 atomes de carbone, de préférence de 14 à 18 atomes de carbone, avantageusement de 16 à 18 atomes de carbone,
• R₂ représente un groupement alkyle saturé linéaire ou ramifié comprenant de 14 à 22 atomes de carbone, de préférence de 14 à 18 atomes de carbone, avantageusement de 16 à 18 atomes de carbone.

In one embodiment of the invention, the fatty amine can be a fatty amine of formula (I) in which:

• R ₁ represents a linear or branched saturated alkyl group comprising from 14 to 22 carbon atoms, preferably from 14 to 18 carbon atoms, advantageously from 16 to 18 carbon atoms,
• R ₂ represents a linear or branched saturated alkyl group comprising from 14 to 22 carbon atoms, preferably from 14 to 18 carbon atoms, advantageously from 16 to 18 carbon atoms.

In another embodiment of the invention, the fatty amine can be a fatty amine of formula (I) in which R ₁ and R ₂ , which are identical, represent a linear or branched saturated alkyl group comprising from 14 to 22 atoms of carbon, preferably from 14 to 18 carbon atoms, advantageously from 16 to 18 carbon atoms.

In a preferred embodiment of the invention, the fatty amine is a fatty amine of formula (Ia):

(R ₁ ) ₂ N-(CH ₂ ) ₃ -NH ₂ (la)

in which R ₁ represents a linear or branched saturated alkyl group comprising from 14 to 18 carbon atoms, preferably from 16 to 18 carbon atoms

• R₁ représente un groupement alkyle saturé linéaire ou ramifié comprenant de 14 à 18 atomes de carbone, de préférence de 16 à 18 atomes de carbone, et
• n représente 1 ou 2.

In another preferred embodiment of the invention, the fatty amine is a fatty amine of formula (Ib):

(R ₁ ) ₂ N-(CH ₂ ) ₃ -[NH(CH ₂ ) ₃ ] _n -NH ₂ (Ib)

in which :

• R ₁ represents a linear or branched saturated alkyl group comprising from 14 to 18 carbon atoms, preferably from 16 to 18 carbon atoms, and
• n represents 1 or 2.

In a more preferred embodiment of the invention, the fatty amine of formula (I) is a fatty amine of formula (Ib-1):

(R ₁ ) ₂ N-(CH ₂ ) ₃ -NH(CH ₂ ) ₃ -NH ₂ (Ib-1)

in which R ₁ represents a linear or branched saturated alkyl group comprising from 14 to 18 carbon atoms, preferably from 16 to 18 carbon atoms.

In another more preferred embodiment of the invention, the fatty amine of formula (I) is a fatty amine of formula (lb-2):

(R ₁ ) ₂ N-(CH ₂ ) ₃ -[NH(CH ₂ ) ₃ ] ₂ -NH ₂ (lb-2)

in which R ₁ represents a linear or branched saturated alkyl group comprising from 14 to 18 carbon atoms, preferably from 16 to 18 carbon atoms.

In one embodiment of the invention, the BN of the fatty amine determined according to the ASTM D-2896 standard ranges from 170 to 340 milligrams of potash per gram of amine, preferably from 180 to 320 milligrams of potash per gram. of amine.

The lubricating composition according to the invention does not comprise fatty amines other than the fatty amine of formula (I).

Thus, the lubricating composition according to the invention comprises only one fatty amine corresponding to a fatty amine of formula (I).

In another embodiment of the invention, the lubricating composition has a BN determined according to the ASTM D-2896 standard of at least 70, preferentially of at least 80, more preferentially of at least 90, advantageously of at least least 95 milligrams of potash per gram of lubricating composition.

In another embodiment of the invention, the lubricating composition has a BN determined according to the ASTM D-2896 standard ranging from 70 to 120, preferentially from 70 to 100, more preferentially from 80 to 100, advantageously from 90 to 100 milligrams of potash per gram of lubricating composition.

In a preferred embodiment of the invention, the lubricating composition has a BN determined according to the ASTM D-2896 standard equal to 100 milligrams of potash per gram of lubricating composition.

In another embodiment of the invention, the mass percentage of fatty amine relative to the total weight of the lubricating composition is chosen so that the BN provided by this compound represents a contribution of 5 to 60 milligrams of potash. per gram of lubricant, more preferably from 10 to 30 milligrams of potash per gram of lubricant to the total BN of said lubricating composition.

In a preferred embodiment of the invention, the mass percentage of fatty amine relative to the total weight of lubricating composition ranges from 2 to 10%, preferably from 3 to 10%, advantageously from 4 to 9%.

In another embodiment of the invention, the lubricating composition has a BN determined according to the ASTM D-2896 standard of at most 50, preferably of at most 40, advantageously of at most 30 milligrams of potash per gram of lubricating composition.

In another embodiment of the invention, the lubricating composition has a BN determined according to the ASTM D-2896 standard ranging from 10 to 30, preferably from 15 to 30, advantageously from 15 to 25 milligrams of potash per gram of composition lubricating.

In a preferred embodiment of the invention, the lubricating composition has a BN determined according to the ASTM D-2896 standard equal to 25 milligrams of potash per gram of lubricating composition.

In a preferred embodiment of the invention, the mass percentage of fatty amine relative to the total weight of lubricating composition ranges from 0.5 to 10%, advantageously from 3 to 10%.

In a preferred embodiment of the invention, the mass percentage of fatty amine relative to the total weight of lubricating composition advantageously ranges from 0.5 to 9%, more advantageously from 0.5 to 8%.

Lubricating base oils

The lubricating composition according to the invention comprises at least one lubricating base oil.

In general, the lubricating base oils used for the formulation of lubricating compositions 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 groups I to V according to the classes defined in the API classification ((or their equivalents according to the ATIEL classification) as summarized below. In addition, the or the lubricating base oils used in the cylinder lubricants according to the invention can be chosen from oils of synthetic origin of group VI according to the ATIEL classification.The API classification is defined in American Petroleum Institute 1509 "Engine oil Licensing and Certification System" 17th edition, September 2012 .

The ATIEL classification is defined in " The ATIEL Code of Practice", issue 18, November 2012 . Saturates content Sulfur content Viscosity index Group I Mineral oils < 90% > 0.03% 80 ≤ IV < 120 Group II Hydrocracked oils ≥ 90% ≤0.03% 80 ≤ IV < 120 Group III Hydrocracked or hydroisomerized oils ≥ 90% ≤0.03% ≥ 120 Group IV PAO (Poly alpha olefins) Group V Esters and other bases not included in bases groups I to IV Group VI* Internal polyolefins (in Anglo-Saxon term Poly Internai Olefins or PIO) *for ATIEL classification only

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

Group II and III oils are obtained by more severe purification processes, for example a combination of hydrotreating, hydrocracking, hydrogenation and catalytic dewaxing.

Examples of synthetic Group IV and V bases include polyisobutenes, alkylbenzenes, and poly-alpha olefins such as polybutenes.

These lubricating base oils can be used alone or in a mixture. A mineral oil can be combined with a synthetic oil.

Cylinder oils for two-stroke marine engines have a viscosimetric grade SAE-40 to SAE-60, generally SAE-50 equivalent to a kinematic viscosity at 100°C of between 16.3 and 21.9 mm ² /s measured according to the standard ASTM D445.

SAE-40 grade oils have a kinematic viscosity at 100°C of between 12.5 and 16.3 cSt measured according to the ASTM D445 standard.

SAE-50 grade oils have a kinematic viscosity at 100°C of between 16.3 and 21.9 cSt measured according to the ASTM D445 standard.

SAE-60 grade oils have a kinematic viscosity at 100°C of between 21.9 and 26.1 cSt measured according to the ASTM D445 standard.

In a preferred embodiment of the invention, the lubricating compositions according to the invention have a kinematic viscosity measured according to the ASTM D445 standard at 100° C. ranging from 12.5 to 26.1 cSt, preferentially from 16.3 to 21 .9 cSt.

This viscosity can be obtained by mixing additives and base oils, for example containing Group I mineral bases such as Neutral Solvent bases (for example 500NS or 600 NS) and Brightstock. Any other combination of mineral, synthetic or plant-based bases having, when mixed with the additives, a viscosity compatible with the SAE-50 grade can be used.

Typically, a conventional formulation of lubricating composition for two-stroke marine engines is of grade SAE-40 to SAE-60, preferably SAE-50 (according to the SAE J300 classification) and comprises at least 40% by weight of lubricating base oil of of mineral, synthetic origin or mixtures thereof, suitable for use in a marine engine. For example, a group I lubricating base oil according to the API classification, i.e. obtained by the following operations: distillation of selected crudes then purification of these distillates by processes such as solvent extraction, dewaxing with solvent or catalytic, hydrotreating or hydrogenation, can be used for the formulation of a cylinder lubricant. Group I lubricating base oils have a Viscosity Index (VI) ranging from 80 to 120; their sulfur content is greater than 0.03% and their content of saturated hydrocarbon compounds is less than 90%.

Other additives

The lubricating composition further comprises at least one additive chosen from overbased detergents and/or neutral detergents.

The overbased detergents or the neutral 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 lubricants 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 or alkaline-earth metal salts of carboxylic acids, sulfonates, salicylates, naphthenates, as well as phenate salts.

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

These metal salts may contain the metal in an approximately stoichiometric amount with respect to the anionic group(s) of the detergent. In this case, we speak of non-overbased or "neutral" detergents, although they also provide a certain basicity. These "neutral" detergents typically have a BN, measured according to ASTM D2896, of less than 150 mg KOH/g, or less than 100 mg KOH/g, or even less than 80 mg KOH/g of detergent.

This type of so-called neutral detergents can contribute in part to the BN of the lubricating compositions according to the present invention. Use will be made, for example, of neutral detergents of the carboxylate, sulphonate, salicylate, phenate, naphthenate type of alkali and alkaline-earth metals, for example of calcium, sodium, magnesium, barium.

When the metal is in excess (in an amount greater than the stoichiometric amount relative to the anionic group(s) of the detergent), we are dealing with so-called overbased detergents. Their BN is high, greater than 150 mg KOH/g of detergent, typically ranging from 200 to 700 mg KOH/g of detergent, preferably from 250 to 450 mg KOH/g of detergent.

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

In the same overbased detergent, the metals of these insoluble salts can be the same as those of the oil-soluble detergents or they can be different. They are preferably chosen from calcium, magnesium, sodium or barium.

Overbased detergents are thus in the form of micelles composed of insoluble metal salts held in suspension in the lubricating composition by the detergents in the form of oil-soluble metal salts.

These micelles can contain one or more types of insoluble metallic salts, stabilized by one or more types of detergents.

Overbased detergents with only one type of detergent soluble metal salt will generally be named after the nature of the hydrophobic chain of the latter detergent.

Thus, they will be said to be of the phenate, salicylate, sulphonate or naphthenate type depending on whether this detergent is respectively a phenate, salicylate, sulphonate 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.

In one embodiment of the invention, the overbased detergent and the neutral detergent can be chosen from carboxylates, sulphonates, salicylates, naphthenates, phenates, and mixed detergents combining at least two of these types of detergents.

In a preferred embodiment of the invention, the overbased detergent and the neutral detergent are compounds based on metals chosen from calcium, magnesium, sodium or barium, preferably calcium or magnesium.

In another preferred embodiment of the invention, the overbased detergent is overbased with insoluble metal salts chosen from the group of alkali and alkaline-earth metal carbonates, preferably calcium carbonate.

In another preferred embodiment of the invention, the lubricating composition comprises at least one overbased detergent and at least one neutral detergent as defined above.

The lubricating composition comprises at least 3% by weight of overbased detergent and/or neutral detergent relative to the total weight of the composition.

Depending on the BN of the desired lubricating composition, a person skilled in the art with his general knowledge will be able to determine the content of overbased detergent and/or neutral detergent to be added to the lubricating composition according to the invention. As mentioned above, in one embodiment of the invention, the lubricating composition has a BN determined according to the ASTM D-2896 standard of at most 50, preferably at most 40, advantageously at most 30 milligrams of potash per gram of lubricating composition, in particular ranging from 10 to 30, preferably from 15 to 30, advantageously from 15 to 25 milligrams of potassium hydroxide per gram of lubricating composition.

In this embodiment of the invention, the lubricating composition need not comprise detergents based on alkali metals or alkaline earth metals overbased with metal carbonate salts.

• les monoalcools gras primaires, secondaires ou tertiaires, dont la chaîne alkyle est saturée ou insaturée, linéaire ou ramifiée et comprenant au moins 12 atomes de carbone, préférentiellement de 12 à 24 atomes de carbone, plus préférentiellement de 16 à 18 atomes de carbone, avantageusement les monoalcools primaires à chaîne alkyle linéaire saturée,
• les esters de monoacides gras saturés comportant au moins 14 atomes de carbone et d'alcools comportant au plus 6 atomes de carbone, préférentiellement les mono- et diesters, avantageusement les monoesters de monoalcools et les diesters de polyols dont les fonctions ester sont distantes au plus de quatre atomes de carbone comptés du côté oxygène de la fonction ester.

The lubricating composition according to the invention may also comprise an additional compound chosen from:

• primary, secondary or tertiary fatty alcohols, whose alkyl chain is saturated or unsaturated, linear or branched and comprising at least 12 carbon atoms, preferably from 12 to 24 carbon atoms, more preferably from 16 to 18 carbon atoms, advantageously primary monoalcohols with a saturated linear alkyl chain,
• esters of saturated monofatty acids comprising at least 14 carbon atoms and of alcohols comprising at most 6 carbon atoms, preferably mono- and diesters, advantageously mono-alcohol esters and polyol diesters whose ester functions are at most distant of four carbon atoms counted on the oxygen side of the ester function.

In one embodiment of the invention, the content of additional compound as defined above ranges from 0.01 to 10%, preferably from 0.1 to 2% by weight relative to the total weight of the lubricating composition .

The lubricating composition can also comprise at least one other additional additive chosen from dispersants, anti-wear additives or any other functional additive.

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

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

Compounds derived from succinic acid are dispersants particularly used as lubricating additives. Succinimides are used in particular, 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, in particular 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, of formaldehyde and of primary or secondary amines, are also compounds used as dispersants in lubricants.

In one embodiment of the invention, the dispersant content may be greater than or equal to 0.1%, preferably from 0.5 to 2%, advantageously from 1 to 1.5% by weight relative to the total weight of the lubricating composition.

Anti-wear additives protect friction surfaces by forming a protective film adsorbed on these surfaces. The most commonly used is zinc dithiophosphate or DTPZn. This category also includes various phosphorus, sulphur, nitrogen, chlorine and boron compounds.

There are a wide variety of anti-wear additives, but the category most used is that of phospho sulfur additives such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates or DTPZn. The preferred compounds are of formula Zn((SP(S)(OR ₃ )(OR ₄ ))2, where R ₃ and R ₄ are alkyl groups, preferably comprising from 1 to 18 carbon atoms. at contents of the order of 0.1 to 2% by weight relative to the total weight of the lubricating composition.

Amine phosphates, polysulfides, especially sulfurized olefins, are also commonly used anti-wear additives.

In lubricating compositions for marine engines, anti-wear and extreme pressure additives of the nitrogen and sulfur type are also usually found, such as, for example, metal dithiocarbamates, in particular molybdenum dithiocarbamate. Glycerol esters are also anti-wear additives. Mention may be made, for example, of mono, di and trioleates, monopalmitates and monomyristates.

In one embodiment, the content of anti-wear additives ranges from 0.01 to 6%, preferably from 0.1 to 4% by weight relative to the total weight of the lubricating composition.

The other functional additives can be chosen from thickening agents, anti-foam additives to counter the effect of detergents, which can be, for example, polar polymers such as polymethylsiloxanes, polyacrylates, antioxidant and/or anti-rust additives, for example detergents organo-metallic or thiadiazoles. These are known to those skilled in the art. These additives are generally present at a content by weight of 0.1 to 5% relative to the total weight of the lubricating composition.

A subject of the invention is also a cylinder lubricant comprising a lubricating composition as described above.

All of the characteristics and preferences presented for the lubricating composition also apply to the above cylinder lubricant.

A subject of the invention is also the use of a lubricating composition as defined above for lubricating a marine engine, in particular a two-stroke marine engine.

All of the characteristics and preferences presented for the lubricating composition also apply to the above use.

A subject of the invention is also the use of a lubricating composition as defined above as a single cylinder lubricant that can be used both with fuel oils with a sulfur content of less than 1% by weight relative to the total weight of the fuel oil, with fuel oils with a sulfur content ranging from 1 to 3.5% by weight relative to the total weight of the fuel oil and with fuel oils with a sulfur content greater than 3.5% by weight relative to the total weight of the fuel oil.

In one embodiment, the subject of the invention is the use of a lubricating composition as defined above as a single cylinder lubricant that can be used both with fuel oils with a sulfur content of less than 1% by weight relative to the total weight of the fuel oil and with fuel oils with a sulfur content ranging from 1 to 3.5% by weight relative to the total weight of the fuel oil.

All of the characteristics and preferences presented for the cylinder lubricating composition also apply to the above use.

In a preferred embodiment of the invention, this use corresponds to the use of a lubricating composition having a BN determined according to the ASTM D-2896 standard of at least 70, preferentially of at least 80, more preferentially of at least 90, advantageously at least 95 milligrams of potash per gram of lubricating composition, in particular ranging from 70 to 120, preferably from 70 to 100, more preferably from 80 to 100, advantageously from 90 to 100 milligrams of potash per gram of lubricating composition, and more particularly having a BN equal to 100 milligrams of potash per gram of lubricating composition.

A subject of the invention is also the use of a lubricating composition as defined above as a cylinder lubricant that can be used with fuel oils with a sulfur content of less than 0.5% by weight relative to the total weight of the fuel oil.

All of the characteristics and preferences presented for the cylinder lubricating composition also apply to the above use.

In a preferred embodiment of the invention, this use corresponds to the use of a lubricating composition having a BN determined according to the ASTM D-2896 standard of at most 50, preferably of at most 40, advantageously of at most 30 milligrams of potash per gram of lubricating composition, in particular ranging from 10 to 30, preferably from 15 to 30, advantageously from 15 to 25 milligrams of potash per gram of lubricating composition.

A subject of the invention is also the use of a lubricating composition as defined above for reducing the formation of deposits in the hot parts of a marine engine, in particular of a two-stroke marine engine.

In a marine engine, in particular in a two-stroke marine engine, certain parts are subjected to high temperatures which can go up to 300°C.

This is preferably the segment-pistons-liner (SPC) zone.

Thus, the lubricating composition, by contact with these hot parts, can be subjected to very high temperatures, hence the need to have increased thermal resistance.

All of the characteristics and preferences presented for the cylinder lubricating composition also apply to the above use.

The invention also relates to a method for lubricating a marine engine, in particular a two-stroke marine engine comprising at least one step of bringing the engine into contact with a lubricating composition as defined above. All of the characteristics and preferences presented for the cylinder lubricant composition also apply to the above process.

The invention also relates to a method for reducing the formation of deposits in the hot parts of a marine engine, in particular of a two-stroke marine engine comprising at least one step of bringing said hot parts of the engine into contact with a composition lubricant as defined above.

All of the characteristics and preferences presented for the cylinder lubricant composition also apply to the above process.

• R₁ représente un groupement alkyle saturé linéaire ou ramifié, comprenant au moins 14 atomes de carbone,
• R₂ représente un groupement alkyle saturé linéaire ou ramifié, comprenant au moins 14 atomes de carbone,
• n représente 0, 1 ou 2,

l'amine grasse ayant un BN déterminé selon la norme ASTM D-2896 allant de 150 à 350 milligrammes de potasse par gramme d'amine.The invention also relates to the use of a fatty amine in a lubricating composition for reducing the formation of deposits in the hot parts of a marine engine, the fatty amine being a fatty amine of formula (I):

R ₁ R ₂ N-(CH ₂ ) ₃ -[NH(CH ₂ ) ₃ ] _n -NH ₂ (I)

in which :

• R ₁ represents a linear or branched saturated alkyl group, comprising at least 14 carbon atoms,
• R ₂ represents a linear or branched saturated alkyl group, comprising at least 14 carbon atoms,
• n represents 0, 1 or 2,

the fatty amine having a BN determined according to the ASTM D-2896 standard ranging from 150 to 350 milligrams of potash per gram of amine.

In one embodiment of the invention, this use makes it possible to reduce the formation of deposits in the hot parts of a 2-stroke marine engine.

All of the characteristics and preferences presented for the fatty amine of formula (I) and for the lubricating composition apply to the above use.

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

Example 1 : evaluation of the heat resistance properties of fatty amines according to the invention

1. 1) Maintien de l'échantillon pendant 2 minutes à une température de 30°C,
2. 2) Montée en température de l'échantillon de 30°C à 800°C selon un gradiant de 10°C/min,
3. 3) Refroidissement de l'échantillon de 800°C à 30°C selon un gradiant de 40°C/min,
4. 4) Maintien de l'échantillon pendant 15 minutes à une température de 30°C.

It is a question of evaluating the thermal resistance of fatty amines according to the invention by the implementation of temperature measurements by thermo-gravimetric analysis (TGA). For this, each sample of fatty amine is heated over a temperature range ranging from 30°C to 800°C and respecting the following steps:

1. 1) Hold the sample for 2 minutes at a temperature of 30°C,
2. 2) Temperature rise of the sample from 30°C to 800°C according to a gradient of 10°C/min,
3. 3) Cooling of the sample from 800°C to 30°C according to a gradient of 40°C/min,
4. 4) Holding the sample for 15 minutes at a temperature of 30°C.

Then, for each sample, the curve representing the evolution of the mass loss of the sample as a function of the temperature was determined.

The temperature corresponding to the inflection point of the curve was then determined; the higher the temperature value, the better the heat resistance of the fatty amine.

• amine grasse 1 : amine grasse de formule (I) dans laquelle R₁ et R₂ sont identiques et représentent un groupement alkyle saturé comprenant de 16 à 18 atomes de carbone et n représente 2 (taux d'insaturations = 0 ; BN = 316 mgKOH/g d'amine),
• amine grasse 2 : amine grasse de formule R-[NH(CH₂)₃]₃-NH₂ dans laquelle R représente un groupement alkyle insaturé comprenant de 16 à 18 atomes de carbone (taux d'insaturations = 50% ; BN = 477 mgKOH/g d'amine),
• amine grasse 3 : amine grasse de formule (I) dans laquelle R₁ et R₂ sont identiques et représentent un groupement alkyle saturé comprenant de 16 à 18 atomes de carbone et n représente 1 (taux d'insaturations = 0 ; BN = 251 mgKOH/g d'amine),
• amine grasse 4 : amine grasse de formule R-[NH(CH₂)₃]₂-NH₂ dans laquelle R représente un groupement alkyle insaturé comprenant de 16 à 18 atomes de carbone (taux d'insaturations = 50% ; BN = 413 mgKOH/g d'amine),
• amine grasse 5 : amine grasse de formule (I) dans laquelle R₁ et R₂ sont identiques et représentent un groupement alkyle saturé comprenant de 16 à 18 atomes de carbone et n représente 0 (taux d'insaturations = 0 ; BN = 197 mgKOH/g d'amine),
• amine grasse 6: amine grasse de formule (R)₂-N(CH₂)₃-NH₂ dans laquelle R représente un groupement alkyle insaturé comprenant de 16 à 18 atomes de carbone (taux d'insaturations = 40% ; BN = 334 mgKOH/g d'amine).

6 different fatty amines were evaluated with the following characteristics:

• fatty amine 1: fatty amine of formula (I) in which R ₁ and R ₂ are identical and represent a saturated alkyl group comprising from 16 to 18 carbon atoms and n represents 2 (unsaturation rate = 0; BN = 316 mgKOH /g of amine),
• fatty amine 2: fatty amine of formula R-[NH(CH ₂ ) ₃ ] ₃ -NH ₂ in which R represents an unsaturated alkyl group comprising from 16 to 18 carbon atoms (unsaturation rate = 50%; BN = 477 mgKOH/g of amine),
• fatty amine 3: fatty amine of formula (I) in which R ₁ and R ₂ are identical and represent a saturated alkyl group comprising from 16 to 18 carbon atoms and n represents 1 (unsaturation rate = 0; BN = 251 mgKOH /g of amine),
• fatty amine 4: fatty amine of formula R-[NH(CH ₂ ) ₃ ] ₂ -NH ₂ in which R represents an unsaturated alkyl group comprising from 16 to 18 carbon atoms (unsaturation rate = 50%; BN = 413 mgKOH/g of amine),
• fatty amine 5: fatty amine of formula (I) in which R ₁ and R ₂ are identical and represent a saturated alkyl group comprising from 16 to 18 carbon atoms and n represents 0 (unsaturation rate = 0; BN = 197 mgKOH /g of amine),
• fatty amine 6: fatty amine of formula (R) ₂ -N(CH ₂ ) ₃ -NH ₂ in which R represents an unsaturated alkyl group comprising from 16 to 18 carbon atoms (unsaturation rate = 40%; BN = 334 mgKOH/g amine).

The results of the 6 fatty amines tested are collated in Table I below. Table I Temperature corresponding to the inflection point (°C) Fatty amine 1 (invention) 343 Fatty amine 2 (comparative) 300 Fatty amine 3 (invention) 338 Fatty amine 4 (comparative) 299 Fatty amine 5 (invention) 326 Fatty amine 6 (comparative) 267

The results show that the fatty amines of formula (I) comprising a fully saturated alkyl group (fatty amines 1, 3 and 5) exhibit better heat resistance compared to fatty amines comprising an unsaturated alkyl group (fatty amines 2, 4 and 6).

Example 2 : evaluation of the thermal resistance properties of lubricating compositions according to the invention

It is a question of evaluating the resistance of lubricating compositions according to the invention by the implementation of temperature measurements by differential scanning calorimetry (in English Differential Scanning Calorimetry or DSC).

• huile de base lubrifiante 1 : huiles minérales de groupe I ou Brightstock de masse volumique comprise entre 895 et 915 Kg/m³,
• huile de base lubrifiante 2 : huiles minérales de groupe I, en particulier dénommée Neutral 600NS de viscosité à 40°C de 120 cSt mesurée selon la norme ASTM D7279,
• paquet détergent comprenant un phénate neutre de BN égal à 145 mg KOH/g de phénate, un phénate surbasé de BN égal à 255 mg KOH/g de phénate surbasé, un sulfonate surbasé de BN égal à 430 mg KOH/g de sulfonate surbasé, un dispersant de type PIB succinimide, un alcool gras qui est un mélange de monoalcools ayant une chaîne hydrocarbonée comprenant de 16 à 18 atomes de carbone et des agents anti-mousse,
• les amines grasses 5 et 6 sont telles que décrites dans l'exemple 1.

For this, various lubricating compositions have been prepared from the following compounds:

• lubricating base oil 1: group I or Brightstock mineral oils with a density of between 895 and 915 kg/m ³ ,
• lubricating base oil 2: group I mineral oils, in particular called Neutral 600NS with a viscosity at 40° C. of 120 cSt measured according to standard ASTM D7279,
• detergent package comprising a neutral phenate of BN equal to 145 mg KOH/g of phenate, an overbased phenate of BN equal to 255 mg KOH/g of overbased phenate, an overbased sulfonate of BN equal to 430 mg KOH/g of overbased sulfonate, a PIB succinimide type dispersant, a fatty alcohol which is a mixture of monoalcohols having a hydrocarbon chain comprising from 16 to 18 carbon atoms and anti-foaming agents,
• fatty amines 5 and 6 are as described in example 1.

The lubricating compositions C ₁ and C ₂ are described in Table II; the percentages indicated correspond to mass percentages. Table II Compositions C1 ₍ invention) C ₂ (comparative) Base oil 1 52.5 55.5 Base oil 2 30.0 30.0 Detergent package 10.0 10.0 Fatty amine 5 7.5 Fatty amine 6 4.5 Total BN (mgKOH/g composition) 25 25

The DSC measurement consists in determining the variation of the thermal flux emitted or received by a sample when it is subjected to a temperature programming, under a controlled atmosphere.

• rampe de température : 10°C/min,
• nacelle en aluminium,
• Débit oxygène : 50 mL/min.

The operating conditions applied were as follows:

• temperature ramp: 10°C/min,
• aluminum nacelle,
• Oxygen flow: 50 mL/min.

The value of the oxidation temperature measured by DSC is given as being the temperature at the onset, indicating the start of exothermic oxidation; the higher this value, the better the thermal resistance of the sample.

The results are collated in Table III below. Table III Compositions C1 ₍ invention) C ₂ (comparative) Onset temperature (°C) 300 289

The results confirm those presented in Example 1; indeed the specific choice of a fatty amine of formula (I) comprising a totally saturated alkyl group (composition C ₁ ) makes it possible to significantly increase the temperature at which oxidation begins, and therefore makes it possible to improve the thermal resistance of the compositions lubricating compared to fatty amines comprising an unsaturated alkyl group (composition C ₂ )

Example 3 : evaluation of the thermal resistance properties of lubricating compositions according to the invention

This involves evaluating the heat resistance of lubricating compositions according to the invention by implementing the ECBT test on aged oil.

For this, different lubricating compositions were prepared from the lubricating base oil 1, the lubricating base oil 2, the detergent package and the fatty amines 1, 2, 3 and 4 as described in examples 1 and 2.

The C ₃ , C ₄ , C ₅ and C ₆ lubricating compositions are described in Table IV; the percentages indicated correspond to mass percentages. Table IV Compositions _C3 (invention) C ₄ (comparative) K ₅ (invention) C ₆ (comparative) Base oil 1 48.5 49.5 48.1 49.1 Base oil 2 24.6 25.0 23.5 25.0 Detergent package 22.1 22.1 22.1 22.1 Fatty amine 1 4.8 fatty amine 2 3.4 Fatty amine 3 6.3 Fatty amine 4 3.8 Total BN (mgKOH/g composition) 74 74 74 74

The thermal resistance of the C ₃ , C ₄ , C ₅ and C ₆ lubricating compositions was therefore evaluated using the ECBT test on aged oil, by which the mass of deposits (in mg) generated under determined conditions is measured. The lower this mass, the better the thermal resistance and therefore the better the engine cleanliness.

This test simulates the behavior of the lubricating composition when it is injected on the hot parts of the engine and in particular on the top of the piston and comprises 3 distinct phases.

The first phase was carried out at a temperature of 310°C.

It uses aluminum beakers which simulate the shape of pistons. These beakers were placed in a glass container, the lubricating composition being maintained at a controlled temperature of the order of 60°C. The lubricant was placed in these containers, themselves equipped with a metal brush, partially immersed in the lubricant. This brush is driven in a rotary motion at a speed of 1000 revolutions per minute, which creates a projection of lubricant on the lower surface of the beaker. The beaker was maintained at the temperature of 310° C. by an electrical resistance heater, regulated by a thermocouple. This first phase lasted 12 hours and the projection of lubricant was continuous for the duration of the test.

The second phase consisted of a neutralization of 50 points of BN of each lubricating composition with 95% sulfuric acid, in order to simulate the phenomenon of neutralization of the composition to approximate the actual conditions of use of the lubricating composition. in a marine engine.

The last phase is identical to the first except that this phase was carried out at a temperature of 270°C.

This procedure makes it possible to simulate the formation of deposits in the piston-ring assembly. The result is the weight of deposits measured in mg on the beaker.

The results are collated in Table V below. Table V Compositions _C3 (invention) C ₄ (comparative) K ₅ (invention) C ₆ (comparative) ECBT on aged oil (mg) 73 127 113 147

The results show that the specific choice of a fatty amine of formula (I) comprising a totally saturated alkyl group (compositions C ₃ and C ₅ ) makes it possible to significantly reduce the formation of deposits at high temperature, and therefore makes it possible to improve the thermal resistance of the lubricating compositions with respect to amines comprising an unsaturated alkyl group (compositions C ₄ and C ₆ ).

Example 4 : evaluation of the rheological properties of lubricating compositions according to the invention

This involves evaluating the rheological behavior of lubricating compositions according to the invention, by measuring the rheology at low shear rates.

The rheology measurements are carried out after neutralization of the various lubricating compositions up to 10 points of residual BN using a cylinder (Anton-Paar MCR 301 rheometer; cylinder: r _i = 13.3mm r _e =14.4mm and angle = 120) at a temperature of 40° C. and at a shear rate of 10 ^-2 s ^-1 .

The values obtained (expressed in Pa.s) correspond to the viscosity of the lubricating composition under shear; the lower this value, the lower the increase in viscosity and therefore the better the rheological behavior.

• un lubrifiant cylindre de référence connu comme ayant un très bon comportement rhéologique ;

These measurements were carried out on the lubricating compositions C ₃ and C ₅ as described in Example 3, to which the following compositions were added:

• a reference cylinder lubricant known to have very good rheological behavior;

This cylinder lubricant is obtained from a mineral lubricating base oil obtained by mixing a distillate with a density at 15° C. of between 880 and 900 kg/m ³ with a distillation residue with a density of between 895 and 915 Kg/m ³ (Brightstock) in a distillate / residue ratio of 3.

• une composition lubrifiante C₇ et une composition lubrifiante C₈ dont les caractéristiques sont décrites dans le tableau VI ci-dessous (les pourcentages indiqués correspondent à des pourcentages massiques)

Tableau VI Compositions C₇ (invention) C₈ (comparatif) Huile de base 1 47,6 48,5 Huile de base 2 22,0 26,0 Paquet détergent 22,1 22,1 Amine grasse 5 8,3 Amine grasse 7 3,4 BN total (mgKOH/g de composition) 74 74 To this lubricating base oil is added a concentrate in which there is an overbased calcium sulfonate with a BN equal to 430 mg KOH/g, a dispersant, an overbased calcium phenate with a BN equal to 255 mg KOH/g and anti-aging agents. -mousse.

• a C ₇ lubricating composition and a C ₈ lubricating composition, the characteristics of which are described in Table VI below (the percentages indicated correspond to percentages by mass)

Table VI Compositions C ₇ (invention) C ₈ (comparative) Base oil 1 47.6 48.5 Base oil 2 22.0 26.0 Detergent package 22.1 22.1 Fatty amine 5 8.3 Fatty amine 7 3.4 Total BN (mgKOH/g composition) 74 74

The fatty amine 5 is as described in Example 1.

The fatty amine 7 is a fatty amine of formula R—[NH(CH ₂ ) ₃ ] ₃ —NH ₂ in which R represents an unsaturated alkyl group comprising from 16 to 20 carbon atoms (unsaturation level of 70%; BN = 471 mgKOH/g amine).

The rheological measurements are described in Table VII below. Table VII Compositions _C3 (invention) K ₅ (invention) C ₇ (invention) C ₈ (comparative) Reference cylinder lubricant Residual viscosity at a shear of 10 ^-2 s ^-1 (in Pa.s) 0.4 0.5 0.4 2.0 0.2

The results show that the specific choice of a fatty amine of formula (I) comprising a totally saturated alkyl group (compositions C ₃ , C ₅ and C ₇ ) makes it possible to minimize the increase in viscosity, in particular at low shear rates, and therefore improves the rheological behavior of lubricating compositions with respect to fatty amines comprising an unsaturated alkyl group (C ₈ composition).

It should be noted that the rheological behavior of the lubricating compositions according to the invention is equivalent to that of the reference cylinder lubricant.

Claims (15)

1. A lubricant composition for marine engines, comprising:

   • at least one lubricant base oil,

   • from 0.1 to 15% by weight, relative to the total weight of lubricant composition, of at least one fatty amine of formula (I):
   
           R₁R₂N-(CH₂)₃-[NH(CH₂)₃]_n-NH₂     (I)
   
   in which:

   • R₁ represents a saturated, linear or branched alkyl group comprising at least 14 carbon atoms,

   • R₂ represents a saturated, linear or branched alkyl group comprising at least 14 carbon atoms,

   • n represents 0, 1 or 2,

   the fatty amine having a BN determined according to standard ASTM D-2896 ranging from 150 to 350 milligrams of potassium hydroxide per gram of amine,

   • at least 3% by weight, relative to the total weight of lubricant composition, of at least one additive chosen from overbased detergents and/or neutral detergents, wherein said lubricant composition does not comprise other fatty amines than the fatty amine of formula (I).
2. The lubricant composition as claimed in claim 1, in which:

   - R₁ represents a saturated, linear or branched alkyl group comprising from 14 to 22 carbon atoms,

   - R₂ represents a saturated, linear or branched alkyl group comprising from 14 to 22 carbon atoms.
3. The composition as claimed in claim 1 or 2, in which R₁ and R₂, which are identical, represent a saturated, linear or branched alkyl group comprising from 14 to 22 carbon atoms.
4. The lubricant composition as claimed in any one of the preceding claims, in which the fatty amine is chosen from:

   - a fatty amine of formula (Ia):
   
           (R₁)₂N-(CH₂)₃-NH₂     (Ia)
   
   in which R₁ represents a saturated, linear or branched alkyl group comprising from 14 to 18 carbon atoms; or

   - a fatty amine of formula (lb-1):
   
           (R₁)₂N-(CH₂)₃-NH(CH₂)₃-NH₂     (Ib-1)
   
   in which R₁ represents a saturated, linear or branched alkyl group comprising from 14 to 18 carbon atoms; or

   - a fatty amine of formula (lb-2):
   
           (R₁)₂N-(CH₂)₃-[NH(CH₂)₃]₂-NH₂     (lb-2)
   
   in which R₁ represents a saturated, linear or branched alkyl group comprising from 14 to 18 carbon atoms.
5. The lubricant composition as claimed in any one of the preceding claims, in which the BN of the fatty amine determined according to standard ASTM D-2896 ranges from 170 to 340 milligrams of potassium hydroxide per gram of amine.
6. The lubricant composition as claimed in any one of the preceding claims, having a BN determined according to standard ASTM D-2896 of at least 70 milligrams of potassium hydroxide per gram of lubricant composition.
7. The lubricant composition as claimed in any one of the preceding claims, having a BN determined according to standard ASTM D-2896 ranging from 70 to 120 milligrams of potassium hydroxide per gram of lubricant composition.
8. The lubricant composition as claimed in any one of the preceding claims, in which the mass percentage of fatty amine relative to the total weight of lubricant composition ranges from 2 to 10%.
9. The lubricant composition as claimed in any one of claims 1 to 5, having a BN determined according to standard ASTM D-2896 of not more than 50 milligrams of potassium hydroxide per gram of lubricant composition.
10. The lubricant composition as claimed in claim 9, having a BN determined according to standard ASTM D-2896 ranging from 10 to 30 milligrams of potassium hydroxide per gram of lubricant composition.
11. The use of a lubricant composition as claimed in any one of claims 1 to 8 as a one-cylinder lubricant which may be used both with fuel oils with a sulfur content of less than 1% by weight relative to the total weight of the fuel oil and with fuel oils with a sulfur content ranging from 1 to 3.5% by weight relative to the total weight of the fuel oil.
12. The use of a lubricant composition as claimed in any one of claims 1 to 5 and 9 to 10 as a cylinder lubricant which may be used with fuel oils with a sulfur content of less than 0.5% by weight relative to the total weight of the fuel oil.
13. The use of a lubricant composition as claimed in one of claims 1 to 10, for reducing the formation of deposits in the hot parts of a marine engine.
14. The use of a fatty amine in a lubricant composition for reducing the formation of deposits in the hot parts of a marine engine,
    the fatty amine being a fatty amine of formula (I):
    
            R₁R₂N-(CH₂)₃-[NH(CH₂)₃]_n-NH₂     (I)
    
    in which:

    • R₁ represents a saturated, linear or branched alkyl group comprising at least 14 carbon atoms,

    • R₂ represents a saturated, linear or branched alkyl group comprising at least 14 carbon atoms,

    • n represents 0, 1 or 2,

    the fatty amine having a BN determined according to standard ASTM D-2896 ranging from 150 to 350 milligrams of potassium hydroxide per gram of amine.
15. A process for lubricating a marine engine comprising at least one step of placing said engine in contact with a lubricant composition as claimed in any one of claims 1 to 10.