WO2021250307A1

WO2021250307A1 - Use of organometallic salt compositions in marine lubricants

Info

Publication number: WO2021250307A1
Application number: PCT/FI2020/050411
Authority: WO
Inventors: Aubrey BURROWS; Samuli LEMPIÄINEN; Sophia VON HAARTMAN; Johan Von Knorring
Original assignee: Ab Nanol Technologies Oy
Priority date: 2020-06-11
Filing date: 2020-06-11
Publication date: 2021-12-16

Abstract

The present invention relates to the use of organometallic salt compositions as lubricant additives and/or lubricant additive compositions, for use in marine engine lubricants, to reduce oil consumption, extend oil change intervals, extend engine service intervals, and enhance engine piston cleanliness, in addition to reducing fuel consumption and increasing wear protection.

Description

USE OF ORGANOMETALLIC SALT COMPOSITIONS IN MARINE LUBRICANTS

Background of the Invention

Field of the Invention

[0001] The present invention relates to the field of marine lubricants and lubricant additives.

[0002] Particularly, the invention relates to the use of organometallic salt compositions as lubricant additives and/or lubricant additive compositions, for use in four-stroke or two-stroke marine engine lubricants, to reduce oil consumption, extend engine service intervals, and enhance engine piston cleanliness, in addition to reducing fuel consumption and increasing wear protection.

Description of Related Art

[0003] Road transport environmental concerns have driven the need to reduce pollutant emissions and achieve fuel economies. As a consequence, engine lubricants have been formulated for vehicles to lower pollution levels and reduce fuel consumption. These fuel-efficient engine lubricants have used friction modifying additives, to reduce the coefficients of friction between metal surfaces that are in sliding motion. By consuming less fuel, not as much polluting gases and particulates are generated.

[0004] Examples of friction modifying additives include organometallic salt compositions, such as those described in WO 2017/005967 and US 10144896. These lubricant and lubricant additive compositions were primarily designed for road transport vehicles.

[0005] However, neither the early conventional engine lubricants nor the later developments in the form of said organometallic salt compositions have been designed with the specific requirements of marine engines in mind. There is thus still increased interest in fuel efficiency and reduced emissions in the field of marine lubricants. At the same time, there is also a strong demand from shipping operators to cut vessel running costs still more, by reducing oil consumption, extending oil change intervals and engine maintenance service intervals, and increasing the lifetime of engine components.

[0006] However, the formulation of fuel-efficient marine lubricants must not be detrimental to the lubricant's other performance parameters. In particular, wear- resistance and engine cleanliness, should not be impaired.

[0007] Marine engines have very different requirements from their lubricants, compared to other lubricants, due to the contrasting mechanical designs and operating conditions, compared to road transport vehicles. The lubrication environment in marine engines is totally different. Marine engines have to work much harder and operate at full speed for much longer intervals. They also only operate with one gear. In addition, an idle marine engine is prone corrosion and lack of lubrication. Marine engines are also subject to constant corrosive attack due to humidity and exposure to water. As a consequence, marine engines are built differently because of this risk of corrosion. Different lubricant formulations are also required to provide satisfactory performance.

[0008] The hardware in marine engines that must be protected by lubricants is different to road vehicles. The camshafts are modified because they must cope with more low-end torque at high RPMs (revolutions per minute). The bearings are also typically larger in marine engines to handle constant RPMs. In addition, the pistons in marine engines are usually geared towards higher compression and the rings must also cope with wet environments. Furthermore, the engines run constantly at 4,500 to 5,000 RPMs for long periods. Marine rated engine blocks must also be manufactured to cope with the additional heat and pressure generated in combustion.

[0009] Marine engines oils have to protect against many marine-specific issues, including corrosion, oxidation, and moisture. The additives have a more critical role than in an automotive oil. Marine oils typically contain 20 to 35 wt% additives. The oils must be able to address the combustion effects of heavy fuel oils and higher sulphur distillate fuels and mitigate corrosion. The engine temperatures are usually higher and this, together with the wet environment, increases the risk of lubricant degradation, and formation of more piston deposits. As a result, the lubrication environmental in marine engines totally different, compared to road vehicles. [0010] There is prior art that describes lubricants for four-stroke marine diesel engines containing at least one fatty amine. This type of compound is generally regarded as an effective friction modifier lubricant additive. However, this prior art gives no specific claims or supporting examples regarding fuel economy properties or other engine performance attributes.

[0011] Said attributes are of considerable importance particularly in the very large marine engines, for example due to the size of the vessels where they have been installed, and due to the other factors described above. Therefore, it would be desirable to have a lubricant specifically designed for marine engines, with demonstrable reductions in marine fuel consumption, while maintaining the lubricant's other performance parameters, in particular engine cleanliness. In addition, the lubricant should improve wear-resistance, reduce oil consumption, enhance engine piston cleanliness, and extend maintenance service intervals, in order to lower operating costs for shipping companies.

Summary of the Invention

[0012] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0013] It is therefore an objective of the present invention to provide a lubricant additive or lubricant additive composition that meets all or part of the above-mentioned requirements, and also overcomes all or part of the aforementioned drawbacks.

[0014] A second objective of the invention is to provide a lubricant additive composition that is easy to implement in lubricants designed specifically for marine engines, especially four-stroke marine engines. [0015] A third objective of the invention to provide a lubricant additive or lubricant additive composition that is effective in reducing fuel and oil consumption, improving wear protection, enhancing engine piston cleanliness, extending oil change intervals, and extending maintenance service intervals, in such marine engines.

[0016] A further objective of the present invention is to provide a lubrication method that improves fuel economy and also improves wear-resistance, reduces oil consumption, enhances engine piston cleanliness, extend oil change intervals, and extends engine maintenance service intervals in marine vessels.

[0017] These objectives are achieved using the present invention, particularly using an additive composition containing or consisting of one or more copper based organometallic salt(s).

[0018] While the primary focus of the present invention is for lubricant and lubricant additives compositions to be used in four-stroke marine diesel engines, this technology is also applicable for use in lubricants for other marine engines, such as two-stroke marine cylinder lubricants.

[0019] Marine engines have very different requirements for their lubricants, compared to other engines and lubricants, and these requirements have now been found to be fulfilled using the claimed composition. [0020] The marine engine lubricants must maintain power output. In order to achieve this requirement, it is vital that the detergent/d ispersant additive system controls of high temperature deposits, on the undercrown of the piston, and the ring belt, enabling piston rings to function efficiently. [0021] The lubricant must also prolong oil life and, therefore, the detergent system is required to provide sufficient base number (BN), combined with good alkalinity retention characteristics to maintain adequate BN, and ensure that corrosive acids formed by the combustion of fuel sulphur are effectively neutralised, thereby minimizing liner wear. This is a particularly important requirement in marine engines, compared to road vehicles, because the sulphur content in marine fuel is up to 5%, whereas road diesel fuel typically contains only 0.001% sulphur. After combustion, sulphur from diesel fuel creates sulfuric acid that causes corrosive wear on the metal surfaces of an engine. Corrosion of a surface within in a dynamic system such as the cylinder wall/liner can lead to corrosive wear, where surface corrosion layers are removed through sliding or abrasion.

[0022] In addition, the lubricant must enable efficient operation of the onboard purifying system. This is a unique requirement for marine engine lubricants, because of the very wet operating conditions, compared to road vehicles. It is important that additives in the marine oil formulation do not impair water separation characteristics, and enable water to be centrifuged out, with essentially no loss of additive performance.

[0023] The ship field tests given in the Examples below demonstrate that the lubricant and lubricant additive compositions in the current invention have fulfilled these requirements. In particular, the claimed compositions contribute to effective control of high temperature engine deposits, do not impair the alkalinity retention characteristics, boost wear protection, and do not harm the water separation properties.

[0024] While developing the present invention, it was surprisingly and unexpectedly found that the organometallic salt compositions described herein, particularly when based on copper salts, reduce oil consumption, enhance engine piston cleanliness, extend oil change intervals, and extend maintenance service intervals particularly effectively in marine engines, in addition to reducing fuel consumption and improving wear protection.

[0025] The present invention thus relates to the use of organometallic salt compositions derived from copper and at least one long chain monocarboxyl ic acid (typically a fatty acid), to prepare lubricant additives or lubricant additive compositions specifically for marine engines.

[0026] Organometallic salts prepared from fatty acids are frequently incorporated into oils and greases to provide lubricating compositions having special properties, including reducing friction and wear. The organometallic salts can be based on different metal elements, with copper-based additives being preferred because of their effectiveness in such lubricants. These additive compositions are capable of improving the energy efficiency of engines and other mechanical equipment. [0027] Copper-based organometallic compounds can give maximum benefit when used as multifunctional additives, to reduce friction and wear in liquid lubricants, or greases, fuels, cutting fluids, and hydraulic fluids.

[0028] Such organometallic salt compositions that are useful in reducing friction and wear, have been previously described, but have not been developed specifically for marine engine purposes.

[0029] In the field of marine engines, development in the last years has focused particularly on efficiency, durability, and extension of oil change intervals, as well as reduced piston cleaning intervals (such as reduction of deposit formation). The requirements for achieving these objectives differ from the requirements of other automotive engines, due to the larger size of marine vessels, the higher power output needs, different fuels used, and the more severe operating conditions.

[0030] Thus, several advantages are achieved using the present invention, by using the lubricant compositions described herein to protect friction surfaces in marine engines. [0031] Among others, a lubricant additive composition has been achieved that has improved capability to reduce oil consumption, enhance engine piston cleanliness, extend oil change intervals, extend maintenance service intervals and extend operational lifetimes of both marine lubricants and marine engines, in addition to reducing fuel consumption and improving wear protection. These benefits have been demonstrated in ship field tests that are described in the examples.

[0032] This lubricant additive composition can be formulated with other suitable components, leading not only to less wear but also reduced friction.

[0033] An additional advantage achieved with the organometallic salt compositions and the lubricant compositions described herein, is that they have a good solubility in a wide range of hydrocarbon base oils (Groups I, II, and III) at a variety of concentrations and in a range of conditions. This is an improvement compared to earlier conventional organometallic salts used in lubricants, since they are typically not particularly soluble in hydrocarbon oils of groups II and III.

[0034] The characterization of hydrocarbon base oils is based on a designation by the American Petroleum Institute. Group !, II, and Ml oils are natural mineral oils. Group I oils are composed of fractionally distilled petroleum which is further refined with solvent extraction processes to improve properties such as oxidation resistance, and to remove wax. Group II oils are composed of fractionally distilled petroleum that has been hydrocracked to further refine and purify it. Group III oils have similar characteristics to Group II oils, with Groups II and III both being highly hydro-processed oils which have undergone various steps to improve their physical properties. Group III oils have higher viscosity indexes than Group II oils, and are prepared by either further hydrocracking of Group II oils, or by hydrocracking of hydro-isomerized slack wax, which is a byproduct of the dewaxing process used for many of the oils in general.

[0035] Good solubility characteristics means that the compositions, based on a visual assessment, are fully miscible with the base oil, and do not separate or form sediments or gels upon storage. The assessment is typically performed at a ambient temperature within the range of 18°C to 24°C.

[0036] As a conclusion, there is achieved effective marine engine lubricants that can ensure long lifetimes of engines by protecting mechanical parts from wear, and enable the self-healing of wear and metal surface damages by selective transfer. Particularly, the present invention provides lubricant additives that result in reduced oil consumption, enhanced engine piston cleanliness, extended oil change intervals, and extended maintenance service intervals in marine engines, particularly four-stroke marine diesel engines. Embodiments of the Invention

[0037] Definitions

In the present context, the term “long chain carboxylic acid” is intended to encompass carboxylic acids having a carbon chain of the length C13 to C22· The chain can be linear or branched.

Similarly, a “short chain carboxylic acid” is intended to cover monocarboxyl ic acids having less than 6 carbon atoms. Thus, a branched short chain monocarboxyl ic acid has 4 or 5 carbon atoms.

Thus, it becomes apparent that a “medium chain carboxylic acid”, in the present context, has 6 to 12 carbon atoms.

[0038] The present invention thus relates to the use of an organometallic salt composition, comprising copper salt(s) of one or more long chain monocarboxyl ic acid(s), as a lubricant additive in marine diesel engine lubricants, to reduce oil consumption, extend oil change intervals, and extend engine service intervals, in addition to reducing fuel consumption and increase wear protection.

[0039] The invention is particularly useful in four-stroke marine diesel engines. [0040] The above-mentioned salt(s) is/are optionally used in combination with one or more short or medium branched-chain monocarboxyl ic acids.

[0041] If used, the content of short or medium branched-chain carboxylic acid in the organometallic salt composition is preferably in the range of 2 to 20 wt%.

[0042] The long chain monocarboxyl ic acids that are useful may be characterized by way of certain common aspects of their structures. The intermediate organometallic salts mentioned above may, more specifically, be derived from the reaction of monocarboxyl ic acids in the range C13 to C22 and the copper salt, such as copper carbonate. [0043] Preferably unsaturated acids are used such as linolenic, linoleic and oleic acids, preferably oleic acid, whereby a preferred salt is copper oleate.

[0044] Examples of other acids that can be employed include saturated monocarboxyl ic acids such as lauric, myristic, palmitic or stearic. Saturated and unsaturated branched monocarboxyl ic acids can also be used, for example iso stearic acid. Optionally naphthenic acids or synthetic carboxylic acids can be used.

[0045] Typically, one or two different salts are used, whereby it is preferred, in case of mixing two salts, to use at least one unsaturated acid, and then select the remaining salt(s) from either saturated or unsaturated ones.

[0046] The preparation of the organometallic salt compositions used in the present invention generally involves the reaction of copper carbonate, with said one or more long chain monocarboxyl ic acid, for example oleic acid, thus forming an intermediate salt. A wide range in the proportions of the carboxylic acid may be employed, preferably such that the molar ratio of the carboxylic acid to the copper carbonate reactant ranges from 1 :1 to 20:1.

[0047] The copper carbonate according to a preferred embodiment of the invention, may be mixed with another metal carbonate, typically comprising one of silver, gold, palladium, cobalt, lead, tin, bismuth, molybdenum, titanium, tungsten and nickel as metal element. More preferably, the other metal carbonate comprises cobalt.

[0048] After preparing the intermediate salt as described above, the optional short or medium chain carboxylic acid may be added, particularly in order to facilitate the formation of a salt that is liquid at room temperature. Before said addition, the intermediate salt is preferably heated to a temperature of at least about 60 °C, and the heating continued until the salt is in liquid form. Then the short or medium chain carboxylic acid may be added with vigorous mixing.

[0049] If adding the short or medium branched-chain monocarboxyl ic acid, it can be advantageous under certain circumstances to use a medium chain acid. For example, one preferred combination of long chain carboxylic acid and short or medium chain carboxylic acid is the combination of oleic acid with 2-ethylhexanoic acid, which has a beneficial effect on the solubility of the composition, and enhanced ambient fluidity liquid properties. [0050] A wide range in the proportions of the short or medium branched chain monocarboxyl ic acid may be employed, such that the weight ratio of the intermediate organometallic salt and the short or medium branched-chain monocarboxyl ic acid may range from 2:1 to 50:1. A ratio of 5:1 to 20:1 is preferred, and the range 10:1 to 20:1 is most preferred.

[0051] Saturated short or medium branched-chain monocarboxyl ic acids are preferred in the present invention. They should contain at least one branched alkyl group. Preferably they contain 4 to 11 carbon atoms, more preferably 6 to 10 carbon atoms, and most preferably 8 carbon atoms. Examples of such saturated short or medium branched-chain monocarboxyl ic acids include 2-ethylhexanoic acid, 2-methylbutyric acid, 2-ethylbutanoic acid, 2-methylpentanoic acid, 3- methylpentanoic acid, 4-methylpentanoic acid, 2-methylhexanoic acid, 5- methylhexanoic acid, 4-methyloctanoic acid, and 4-methylnonanoic acid, preferred alternatives being 2-ethylbutyric acid and 2-ethylhexanoic acid, and a particularly preferred alternative being 2-ethylhexanoic acid.

[0052] In an embodiment of the invention, the organometallic salt composition described above is combined with further additive components, to form a lubricant additive composition.

[0053] Particularly, the organometallic salt composition can be combined with an activated complex containing a first metal component, a second metal component, and particles comprising the first metal component. Thus, not all of the first and second metal components are necessarily linked to the particles. This combination has been found to give a reduction of oil consumption, enhanced engine piston cleanliness, extended oil change intervals, and extended maintenance service intervals in marine engines, in addition to reduced fuel consumption and improved wear protection in marine engines. It is particularly the case when particles, such as nanoparticles, are produced in-situ to provide a lubricant additive composition, and the particles include the first metal component in metallic form. The second metal component is able to participate in reducing the metal element in the first metal component.

[0054] Preferably, the first metal component of the activated complex comprises gold, silver, copper, palladium, tin, cobalt, zinc, bismuth, manganese and/or molybdenum, especially preferably copper and/or cobalt, more preferably copper.

[0055] The second metal component of the activated complex preferably comprises tin, bismuth, zinc, and/or molybdenum, especially preferably, tin, bismuth and/or zinc, more preferably tin. Also, the second metal component can be added in the form an inorganic or organometallic salt. Thus, it can be advantageous to include the first metal component, in metallic form, as particles, including the second metal component.

[0056] However, according to a preferred embodiment, particles, preferably nanoparticles, are formed from the first metal component in metallic form, with the second metal component is also present as an inorganic salt.

[0057] The particles of the activated complex, comprising the first metal component, exhibit a diameter in the range of 1 to 10,000 nm, preferably in the range of 5 to 1,000 nm, more preferably in the range of 10 to 500 nm, especially preferably in the range of 15 to 400 nm.

[0058] The bimetallic activated complex preferably further contains any solvents, dispersants, and surfactants needed to disperse the nanoparticles in reverse micelles, within a stable colloid, to ensure the particles are completely oil soluble, with no agglomeration or sedimentation of the particles. Further, the activated complex preferably contains at least one reducing agent, e.g. diphenyl amine or hexadecyl amine.

[0059] The surfactants or dispersants can be components that function as ligands. Thus, the ligands can be either surfactants or dispersants; examples are succinimide, polyethoxylated tallow amide and diethanol amine. The solvents or co-solvents can be alcohols, such as glycols with alkyl groups having 1 to 20 carbon atoms, e.g. diethylene glycol. Further, an alcohol having 1 to 20 carbon atoms, preferably 4 to 12 carbon atoms, such as octanol, is advantageously present.

[0060] As stated above, the activated complex preferably comprises particles including the first metal component and optionally the second metal component. At least one compound improving the solubility of the metal element particles may thus be added, e.g. epoxy resin of diethylene glycol or epoxidized dipropylene glycol. These preferred components are typically added to the particles of the first metal component.

[0061] Preferably, the lubricant additive composition described above comprises a soluble metal compound derived from the first metal component. If at all possible, this lubricant additive composition is able to form metal plating.

[0062] Preferably, the weight ratio of the organometallic salt composition to the activated complex is in the range of 10,000:1 to 1 :1. The preparation of the relevant activated complexes, and their combination with organometallic salt compositions, to give the products that can be used according to the present invention, is illustrated further in example 1, 2, and 3 below. Processes for obtaining the activated complex referred to above are disclosed in further detail in WO201 5/173421, hereby incorporated by reference.

[0063] Based on the above, it is particularly preferred to use the organometallic salt composition, as described above, combined with an activated complex containing particles, comprising a first metal component, as part of a lubricant additive composition for marine diesel engines.

[0064] Likewise, it is particularly preferred to use the organometallic salt composition, as described above, combined with an activated complex containing particles, comprising a first metal component, as part of a lubricant composition for marine diesel engines.

[0065] The final lubricant composition is typically used in a ratio of oil to lubricant of 95:5 to 99.8:0.2, preferably in a ratio of 97:3 to 99.7:0.3.

[0066] It has been found that the friction and wear performance of lubricant additive and lubricant compositions can be significantly improved in four-stroke marine diesel engines, when using the organometallic salt composition described above, particularly when used in the mentioned ratios.

[0067] It has also been found that such lubricant additive and lubricant compositions can significantly reduce fuel consumption, and increase wear protection, in four-stroke marine diesel engines.

[0068] In addition, it has also been surprisingly and unexpectedly found that the oil consumption can be significantly reduced, and the intervals between oil changes and engine maintenance services can be extended, in four-stroke marine engines, with use of the lubricant additive and lubricant compositions.

[0069] The reduced fuel consumption performance is achieved by the lubricant additive composition having the capability to function as a friction modifier. This involves the formation of a tribofilm on the metal surfaces to reduce the coefficient of friction. This reduces energy losses in the engine and increases fuel efficiency.

[0070] The improved wear protection performance is achieved by the lubricant additive composition as described herein forming a tribofilm on the metal surfaces to reduce metal-metal contact and prevent damages.

[0071] The reduced oil consumption is achieved by the lubricant additive composition forming a tribofilm on the metal surfaces of the piston rings and cylinder liners. This reduces wear in the piston zone and also ensures a tighter gap is maintained between the piston and cylinder wall, as well as the piston oil ring groove. This reduces the amount of lubricant lost from the sump to the combustion chamber and burnt. This lost lubricant must be replaced to maintain the required level of lubricant in the engine sump.

[0072] The enhanced engine piston cleanliness, extended oil change intervals, and longer intervals between major engine services, are, in turn, achieved by the reduction of temperatures in the oil sump. This due to less heat being generated as a consequence of lower friction. This puts less thermal stress on the lubricant, reduces the rate of oil degradation, and deposits build-up in the piston zone. It extends the useful life of the lubricant, before it must be changed. [0073] The lower rate of wear also places less demands on the other anti wear additives in the lubricant formulation, which further extends the useful life of the lubricant, before it must be changed. In addition, the lubricant additive composition enables longer intervals before major mechanical servicing is required, to clean the pistons and change cylinder liners.

[0074] These performance enhancements all help together to significantly lower ship operating costs.

[0075] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0076] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[0077] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. In addition, various embodiments and examples of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention. [0078] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In this description, numerous specific details are provided to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details.

[0079] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0080] The following non-limiting examples are intended merely to illustrate the advantages obtained with the embodiments of the present invention.

EXAMPLES

Example 1: Preparation of an organometallic salt according to the present invention

[0081] The organometallic salt of the present invention can be prepared by reacting a metal salt with a fatty acid, so that the metal content of the added metal salt provides a metal concentration in the final product salt in the range of 8 to 9 wt%. The reaction typically proceeds at a temperature of at least 60°C until the salt is in liquid form.

[0082] In a more precise procedure, a copper carbonate was reacted with oleic acid, to obtain a copper oleate, so that the copper concentration in the final salt was in the range of 8 to 9 wt%. The reaction was conducted in an oxygen-free environment for 16h at 150°C. The metal content was verified by analysis with MP- AES. Example 2: Preparation of a modified organometallic salt according to the present invention

[0083] A modified organometallic salt of the present invention can be prepared by reacting a metal salt with a fatty acid, so that the metal content of the added metal salt provides a metal concentration in the final product salt in the range of 8 to 9 wt%, as described in Example 1. Thereafter, a branched short- or medium-chained monocarboxyl ic acid is added, using a wide range of proportions, such as 2 to 50 wt% of the total mass of the mixture.

[0084] In a more precise procedure, a copper carbonate was reacted with oleic acid, to obtain a copper oleate, so that the copper concentration in the final salt was in the range of 8 to 9 wt%. The reaction was conducted in an oxygen-free environment for 16h at 150°C. After said reaction, 2-ethylhexanoic acid was added at a ratio of 8 wt% of the total mass of the mixture. This addition will result in a copper-based organometallic salt composition that is liquid at room temperature and has a melting point of 10°C, whereas a copper oleate with a metal content in the range of 8-9 wt%, not containing the branched short-or medium-chain monocarboxyl ic acid, has a melting point of 55°C.

Example 3: Preparation of an activated complex according to the present invention

[0085] The preparation of the activated complex involves a three-step process.

[0086] The first step is preparation of copper (II) chloride solution. Diethylene glycol (about 3.5 kg) was placed in a glass-lined vessel fitted with a stirrer and heating capability. This was heated to about 40°C and copper chloride (0.357kg) was slowly added with stirring to ensure the material is totally dissolved. C-5A succinimide (2.1 kg) was then slowly added with stirring but no heating. Diphenylamine (1.72kg) was next added in small portions and the mixture was stirred to ensure it was homogenous. Finally, DEG-1 epoxy resin (diethylene glycol 1 , 1.86kg) was added and thoroughly stirred. [0087] The second step is preparation of tin (IV) chloride solution. In a separate glass-lined vessel fitted with a stirrer and heating capability, tin (IV) chloride pentahydrate (4.2kg) was dissolved in octanol (about 9.8kg) by stirring the mixture at about 40°C.

[0088] The third step is making of the activated complex. In a separate glass- lined vessel fitted with a stirrer and cooling capability, the tin (IV) chloride solution prepared above was added to the copper (II) chloride solution, also prepared above, under stirring. The tin (IV) chloride solution was added in small portions and the temperature was maintained below 50°C. After the addition was complete the mixture was stirred for a further period to ensure it was homogenous.

Example 4: Preparation of a lubricant additive composition according to the present invention

[0089] A lubricant additive composition of the present invention was prepared by mixing the activated complex from Example 3, with the copper-based organometallic salt composition from example 1. This was carried out by slowly adding the activated complex (23.5 kg) to the copper oleate (about 970 kg) in a glass-lined vessel fitted with a stirrer and heating capability. The temperature of the mixture was maintained in the range 60°C to 70°C, and vigorously stirred for a further period of 30 minutes to ensure it was homogenous.

Example 5: Tribological effects of the lubricant additive composition

[0090] The tribological effects of the organometallic salt composition in Example 4 was demonstrated in tribology tests on a ball-on-three-plates system. The composition was added to Chevron Taro 30 DP 40 in concentrations of 0.3 wt%, 1 wt% and 3 wt% and heated to 60°C to 70°C under stirring for 15 min. The homogeneous oil mixtures were allowed to cool at ambient conditions. The samples were tested by tribological measurements using an Anton Paar rotational rheometer.

[0091] The measurement started with a running-in phase to ensure stable measuring conditions. It was done at 1200 rpm for 30 minutes. After running-in the friction behaviour was measured in the “Striebeck phase” during the next 10 minutes. The measuring regime started at Orpm and the speed was increased during the 10 minutes to 3000 rpm. The normal force was 6 N and the temperature 100°C throughout the measurement. Wear was measured by analysing the wear scars on the plates with optical microscope, and imaging software after friction analysis.

[0092] The following parameters were used for the for friction and wear tests:

[0093] The results of this testing are given in Tables 1 and 2.

Table 1 - Friction behaviour of the samples

Table 2 - Wear behaviour of the samples

[0094] From the tribology measurements, it became apparent that the composition of the present invention has an advantageous impact on the friction and wear behaviour.

Example 6: Water separation properties of the lubricant additive composition [0095] Some lubricant additives that are oil-soluble surfactants can harm the water-separation properties of marine lubricants and lead to an increased the risk of bearing lacquering and cavitation. It is also known that some lubricant additives have poor hydrolytic stability in the presence of water. The ASTM D1401 test method is used to determine the water separability properties of lubricants. The method requires 40 ml of the test oil and 40 ml of water are vigorously stirred together in a graduated cylinder. The separation time of the oil and water emulsion is recorded at 5 minutes intervals. The test limit is 3 ml maximum emulsions remaining after 30 minutes. Tests were run with a commercial marine oil (Chevron Taro 30 DP 40) without and then with 0.3 wt% of the lubricant additive in the current invention. The results in each case was that there was 0 ml emulsion remaining after 15 minutes. This demonstrates that the lubricant additive does not harm or degrade the water separation properties of the marine oil.

Example 7: Ship field tests with the lubricant additive composition

[0096] Ship field tests were carried out to demonstrate the performance benefits of the lubricant additive, and lubricant compositions, of the present invention. The field tests were conducted on vessels powered by four-stroke marine diesel engines, that were engaged in commercial activities transporting people, vehicles, and goods, on regular routes. The ships had a good history of satisfactory performance prior to starting the tests. The vessels also had detailed records of operational parameters, as well as appropriate equipment to accurately measure the amount of fuel consumed. [0097] The lubricant compositions for these ship field tests were prepared by top-treating commercial marine engine lubricants, with the lubricant additive composition prepared in Example 4. It is noted that these commercial marine diesel engine lubricants had been approved by marine diesel engine manufacturers. The rate of fuel usage and oil consumption were measured in the field tests. Data is presented from used oils analyses to measure the level of wear metals. In addition, parts from the engines were visually inspected to assess the rate of wear and general condition.

[0098] A summary of the results from the ship field tests is as follows:

[0099] M/S Fjardvagen - This trial was conducted with Rederi Ab Lillgaard. The ship has been in Rederi Ab Lillgaard’s ownership since 1995 and operated a continuous daily route between Langnas (Aland) and Naantali (Finland). It was built in 1972 and had 2 x 4000 Pielstick 8L main engines. The fuel was marine diesel fuel (MDO). The measurement of fuel consumption showed a reduction 4%, with the lubricant top treated with additive composition, compared to the basic lubricant with no additional additives. The main engines completed more than 17,000 trouble-free operating hours with the lubricant additive. Notably, the service and oil change intervals were also successfully increased from 15,000 to 20,000 hours, with no further problems reported. Parts from the engines were visually inspected by a marine engineer to confirm everything was in satisfactory condition, when routine engine maintenance was carried out. In particular, it was found that the piston cleanliness was good.

[00100] M/V Fingard - The trial was conducted with the shipping company Bore Ltd. The vessel was owned Bore Ltd. The ship was built in 2000. The main engines were Deutz TBD 645 L6 and the fuel was heavy fuel oil (HFO). It operated mainly in the Baltic Sea. Fuel consumption was lowered by 5%, during the first 12 months of operation with a commercial oil top treated with the lubricant additive composition. This equated to over 12,000 operational hours.

[00101] M/S Viking - The trial was conducted with Viking Line. The ship was built in 2008.lt was a cruise ferry and carried passenger traffic on daily basis between Helsinki (Finland) and Tallinn (Estonia). The test was first carried out in the auxiliary engines, which were 3 x Wartsila 8L20. The test was then expanded to the main engines, which were 4 x Wartsila 8L46F. The fuel was a mix of MDO and HFO. The collected data showed a reduction of the fuel consumption of between 3% and 5% with the lubricant additive composition.

[00102] M/V TransReel - The trial was conducted with Transatlantic Shipping, based in Sweden. The ship was built in 1987. It was a roll-on roll-off ferry for passengers and vehicle traffic. The focus of the test was on oil consumption. The test was carried out in the two main engines, which were Wartsila 9R32 and Wartsila 12V32. The collected data showed a reduction of 9.6 wt% oil consumption in the first engine (from 1.2 l/h to 1.09 l/h), and 25.6 wt% reduction in the second engine (from 1.03 l/h to 0.77 l/h) with the lubricant additive composition.

[00103] M/V Seagard - The trial was conducted with Bore Ltd. The ship was built in 1999. It was a roll-on roll-off ferry for passengers and vehicle traffic. The focus of the test was on used oil analysis, in particular to assess the rate of wear. This test was carried out in the one of the main engines, which was Wartsila 16V46B. The fuel was a mix of MDO and HFO. The collected data showed effective wear protection with the lubricant and the lubricant additive composition. The wear metal levels in the used oil before top-treating with the lubricant additive composition were iron 20 ppm; chromium 0 ppm; and lead 0 ppm. The oil was then top-treated with the lubricant additive composition. The test was for 2,500 hours of operation. The collected data showed that wear metal levels in the used oil after top-treatment with the lubricant additive composition, were iron 19 ppm; chromium 0 ppm; and lead 0 ppm. This data shows that there was no increase in any of the wear metal levels, after top-treating with the lubricant additive composition. In particular, the used oil contained 20 ppm iron before the lubricant additive composition top-treat, which indicates a normal rate of wear. Significantly, there was no increase iron levels after the lubricant additive composition top-treat, which is an indicates a zero rate of wear. This is evidence of the wear protection provided by the lubricant additive composition in the present invention.

[00104] M/V Seagard - The good alkalinity retention properties of the lubricant additive composition in the present invention were also demonstrated in the M/V Seagard ship test. The used oil analytical data was also used to assess BN retention. The BN level in the used oil before top-treating with the lubricant additive composition was 27. The oil was then top-treated with the lubricant additive composition, and BN level was remeasured. It was the same at 27. The test was continued for 2,500 hours of operation. The collected data showed that BN level in the used oil after top-treatment with the lubricant additive composition, remained constant at 27. The BN data after 2,500 hours of operation was shows that there was no decrease and it stayed at 27. Significantly, there was no decrease in BN, which indicates no loss of alkalinity retention. This is evidence that the lubricant additive composition in the present invention does not erode alkalinity retention.

[00105] M/V Seagard - The good antioxidant properties of the lubricant additive composition in the present invention were also demonstrated in the M/V Seagard ship test. The used oil analytical data was also used to assess the rate of oxidative degradation. The kinetic viscosity at 100°C (KV100°C) of the used oil before top-treating with the lubricant additive composition was 14.1 cSt. The oil was then top-treated with the lubricant additive composition and the KV100°C was the same at 14.1 cSt. The test was continued for 2,500 hours of operation. The collected data showed that the KV100°C of the used oil was 14.2 cSt. The viscosity index, oxidation, nitration, sulphation, and dispersancy used oil data also remained constant. This shows that after 2,500 hours of operation with the lubricant additive, there was no degradation of the lubricant. Significantly, there no increase in oxidation. This is evidence that the lubricant additive composition in the present invention does not erode oxidative stability and it actually acts as an antioxidant.

Industrial Applicability

[00106] The present invention can be used to reduce oil consumption, extend oil change intervals, and extend engine service intervals, in addition to reducing fuel consumption and increasing wear protection in lubricants for four-stroke marine diesel engines. Citation List

US 10144896 WO 2015/173421 WO 2017/005967

Claims

1. Use of an organometallic salt composition, comprising copper salt(s) of one or more long chain monocarboxyl ic acid(s), as a lubricant additive in marine diesel engine lubricant compositions, to reduce oil consumption, extend oil change intervals, and extend engine service intervals, in addition to reducing fuel consumption and increase wear protection.

2. The use of an organometallic salt composition according to claim 1 in lubricants designed for marine diesel engines to enhance piston cleanliness, and not to degrade alkalinity retention, oxidation stability, or water separation properties of the oil.

3. The use of an organometallic salt composition according to claims 1 and 2 in lubricants designed for four-stroke marine diesel engines.

4. The use of an organometallic salt composition according to claims 1 , 2, and 3, wherein the long chain carboxylic acid is an unsaturated acid.

5. The use of an organometallic salt composition according to claim 1 , 2, and 3, wherein the long chain carboxylic acid is linolenic, linoleic or oleic acid, preferably oleic acid.

6. The use of an organometallic salt composition according to claim 1 , 2, and 3, wherein the copper salt of the one or more long chain carboxylic acid is copper oleate.

7. The use of an organometallic salt composition according to claim 1 , 2, and 3, wherein the composition comprises the salt of one or two different long chain monocarboxyl ic acids.

8. The use of an organometallic salt composition according to claim 1 , 2, and 3, wherein the composition is prepared using the step of reacting a long chain carboxylic acid with copper carbonate.

9. The use of an organometallic salt composition according to claim 8 wherein the molar ratio of the carboxylic acid to the copper of the carbonate reactant is in the range 1 :1 to 20:1.

10. The use of an organometallic salt composition according to any preceding claims, wherein the organometallic salt composition is combined with further additive components, to form a lubricant additive composition.

11. The use of an organometallic salt composition according to any preceding claims, wherein the organometallic salt composition is combined with an activated complex, comprising a first metal component, a second metal component, and particles comprising a first metal component, to form a lubricant additive composition.

12. The use of an organometallic salt composition according to claim 11 , wherein the first metal component comprises gold, silver, copper, palladium, tin, cobalt, zinc, bismuth, manganese and/or molybdenum, preferably copper and/or cobalt, more preferably copper.

13. The use of an organometallic salt composition according to claim 11 , wherein the second metal component comprises tin, bismuth, zinc, and/or molybdenum, preferably tin, bismuth and/or zinc, more preferably tin.

14. The use of an organometallic salt composition according to any preceding claims, combined with an activated complex comprising a first metal component, a second metal component, and particles comprising a first metal component, as part of a lubricant composition for marine diesel engines.

15. Use of an organometallic salt composition, comprising a copper salt of one or more long chain monocarboxyl ic acid(s), in a method for lubricating marine engines.