WO2021250306A1

WO2021250306A1 - Oil-soluble nanoparticles for use in metal-plating additives

Info

Publication number: WO2021250306A1
Application number: PCT/FI2020/050410
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 nanoparticles suitable for use in lubricants, prepared from an activated complex comprising a copper(II) salt and one or more further inorganic metal salt(s), and combined with an organometallic salt composition comprising a copper salt of one or more long chain monocarboxylic acid(s). The invention also relates to a metal-plating additive system and a lubricant additive composition, both comprising said combination of salt composition and activated complex.

Description

OIL-SOLUBLE NANOPARTICLES FOR USE IN METAL-PLATING ADDITIVES

Background of the Invention Field of the Invention

[0001] The present invention relates to the use of organometallic salt compositions, in combination with bimetallic or multimetallic activated complexes, to produce oil soluble and stable nanoparticles, which have optimal metal-plating characteristics. The invention also relates to said nanoparticles.

[0002] These oil soluble nanoparticles are particularly useful in lubricant additives and/or lubricant additive compositions to function as metal-plating and film-forming agents on metal surfaces to significantly reduce friction and wear.

Description of Related Art

[0003] Organometallic salts prepared from fatty acids are frequently incorporated into oils and greases to provide lubricating compositions having special properties. The organometallic salts can be based on different metal elements, with copper-based additives being preferred because of their effectiveness in such lubricants. [0004] Several types of copper compounds including copper dithiophosphates, dithiocarbamates, sulphonates, carboxylates, acetylacetones and phenates, as well as copper stearate and palmitate, have been shown to significantly reduce friction and wear. [0005] Copper-based organometallic compounds can be used as multifunctional additives to reduce friction and wear in liquid lubricants and greases. [0006] Copper nanopartic!es also have promising effects on friction and wear reduction in automotive, mining, and other industrial lubricant applications (see e.g. WO2017/005967 A1). [0007] The enhanced performance of copper based organometallic compounds when used in combination with nanoparticles to function as metal plating additives have been described in WO2015/173421 A2.

[0008] A major challenge is that the nanoparticles are inherently not miscible or dispersible in oil.

[0009] Copper nanoparticles are normally produced externally before being added to the lubricant compositions. These particles are unstable, difficult to disperse, and are not truly oil soluble.

[0010] The particles have a strong tendency to agglomerate together and sediment from lubricants. As a result, the nanoparticles and lubricant compositions lose the capacity to reduce friction and protect against wear. Consequently, the lubricants have inferior performance when used in engines and other mechanical equipment.

[0011] A stable suspension of nanopartic!es is essential for a lubricant to be usable. The aggregation of nanoparticles limits their ability to lubricate the contact areas in mechanical equipment, and cannot reduce of friction or wear when mixed with lubricating oils. A further challenge is the difficulty to control reactivity of the nanoparticles. These factors are critical for producing good metal-plating additives.

[0012] Furthermore, despite all the advances with copper nanoparticles in lubricant additives and lubricant oil formulation technologies, there remains an important need to develop effective dispersions of copper nanoparticles that are also capable of forming of effective tribosystems, which are essential to reducing friction and wear with lubricants. Summary of the Invention

[0013] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0014] According to a first aspect of the present invention, there is provided oil soluble nanoparticles that overcome the above-mentioned drawbacks, particularly relating to agglomeration and sedimentation, and also have robust metal-plating characteristics.

[0015] According to a second aspect of the present invention, there is provided an additive composition containing or consisting of copper based organometallic salts in combination with an activated complex that form nanoparticles, that not only reduces friction, but also provides increased wear protection, particularly when used in liquid lubricants or greases.

[0016] According to a third aspect of the invention, there is provided high- performance lubricants that can ensure long-life operation of mechanical systems, by protecting mechanical parts from contact fatigue damages; also protect friction surfaces from hydrogen wear; and enable the self-healing of wear and damages by selective transfer.

[0017] Likewise, there is provided lubricant additive compositions that have superior metal-plating characteristics, as well as superior friction and wear performance compared to the prior art.

[0018] The invention is based on the surprising and unexpected finding that that the organometallic salt compositions described herein, when combined with activated complexes to produce nanoparticles, made by the in-situ process also described herein, have superior performance, compared to nanoparticles in the prior art. These nanoparticles of the invention have been found to have the ability to form metal plating on friction surfaces, if the components forming the nanoparticles have been selected as described herein. [0019] It is known that the type of organometallic salts that have been used herein have been successfully used in lubricants with other conventional additive components, that are based on macroparticles. It is also known that this type of organometallic salt can be used in lubricants with other additive components containing nanoparticles.

[0020] However, it has not been possible to regulate the reactivity and interaction of nanoparticles with metal surfaces, which is important for optimising metal-plating performance. In addition, it has not been possible to control the way that the nanoparticles create and maintain effective tribofilms on metai surfaces. These processes are essential to maximising the reduction of friction and wear in lubricants.

[0021] Thus, the present invention relates to nanoparticles suitable for use in lubricants, prepared from a combination of an organometallic salt composition and an activated complex.

[0022] The organometallic salt compositions are derived from copper and at least one long chain monocarboxyl ic acid (typically a fatty acid) that is combined with bimetallic or multimetallic activated complexes to produce oil soluble and stable nanoparticles.

[0023] Oil soluble metallic components are well known in the art, but the nanoparticles produced from such conventional components have typically lost their solubility.

[0024] The activated complexes of the present invention comprise a carefully balanced bimetallic or multimetallic, system that may also contain further components, which facilitates the formation of oil soluble nanoparticles in-situ, with the copper-based organometallic salt compositions. The nanoparticles are typically produced by an electrochemical redox reaction between two metallic inorganic salts. The activated complexes may also contain reducing agents, which facilitate the redox reaction. In addition, the activated complexes may contain a mixture of surfactants and dispersants. These facilitate the formation of particles dispersed in reverse micelle, within a stable colloid in oil. Additionally, other cosolvents may be used in the activated complexes to improve the solubility, stability, and effectiveness of the overall colloidal additive system. The thus produced particles have been found to have a typical size in the range 25 to 50 nm.

[0025] The activated complexes are essential to not only produce nanoparticles, but also control the reactivity with metal surfaces, in order to optimise the metal-plating characteristics. These factors contribute to the effective formation of tribofilms in lubricants, that maximise reduction friction, provide increased wear protection, enable longer oil drain intervals, require reduced maintenance, and have extended operational lifetimes.

[0026] The specific chemistries and relative amounts of each constituent in the activated complex are preferably carefully selected. This facilitates production of dispersed nanoparticles in stable colloids. The particles must not only be oil soluble but also be capable of participating in the metal-plating process. This involves particles being released from the micelles, deposited on the metal surface, and then reorganised and self-assembled to form an adsorbed film. It also requires that a dynamic equilibrium is established between particles in solution and in the tribofilm film on the metal surface. [0027] The order of addition of the components and blending conditions for the activated complex also affect the desired and optimised lubricant additive composition. In addition, all steps of this process are preferably carried out in a rigorous manner, in order to produce nanoparticles that give the required performance characteristics in lubricant compositions.

[0028] It has been found possible to control the type, amount, and characteristics of the particles by changing the composition of the activated complexes. These are the levers in the “molecular machine” that enables the type of particles to be fine-tuned, and thereby improves the metal-plating characteristics, and also creates the boosted additive composition.

[0029] It has also been found possible to significantly improve the friction and wear performance of the lubricant additive compositions by changing the relative amounts of the copper-based organometallic salt compositions combined with the activated complexes. [0030] As a conclusion, the advantages achieved using the present invention include, among others, lubricants having a maximized reduction of friction and wear, as well as optimized metal-plating characteristics. Particularly, these lubricants provide engines with reduced friction, increased wear protection, longer oil drain intervals, reduced maintenance requirement, and extended operational lifetimes.

Embodiments of the Invention

[0031] 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.

Solubility in oil is in the present context intended to include products having a high solubility in all four types of hydrocarbon base oils (Groups l-IV) at a variety of concentrations and a variety of conditions. The characterization of hydrocarbon base oils is based on a designation by the American Petroleum Institute. Group I, II, and III 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 111 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.The solubility is assessed visually, whereby a high solubility means that the product is fully miscible with the base oil, and does not separate or form sediments or gels upon storage. The assessment is typically performed at a temperature within the range of 18-24 °C.

“Metal plating”, as described herein, is intended to mean the deposition of metal components on friction surfaces, the latter typically being metal surfaces of engines or machine parts, e.g. made of steel, the deposition being facilitated by the metal components having higher ionization energies and/or higher redox standard potentials than that of the friction surfaces.

[0032] The present invention relates to nanoparticles suitable for use in lubricants, prepared from an activated complex comprising a copper(ll) salt and one or more further inorganic metal salt(s), and combined with an organometallic salt composition comprising a copper salt of one or more long chain monocarboxyl ic acid(s).

[0033] The invention also relates to a metal-plating additive system and a lubricant additive composition, both comprising said combination of salt composition and activated complex.

[0034] Based on the above definition, said long chain monocarboxyl ic acid(s) for the organometallic salt composition is/are typically selected from linear or branched C13 to C22 monocarboxyl ic acids. Preferably, the long chain carboxylic acid(s) is/are unsaturated acid(s). Examples of suitable acids include linolenic, linoleic or oleic acid, a particularly preferred one being oleic acid. The copper salt of the one or more long chain carboxylic acid is thus preferably copper oleate. [0035] In a preferred embodiment, the organometallic salt composition comprises the salts of two different long chain monocarboxyl ic acids.

[0036] The copper salt of the long chain monocarboxyl ic acid(s) is optionally combined with one or more short or medium branched-chain monocarboxyl ic acids.

[0037] Saturated short or medium branched-chain monocarboxyl ic acids are preferred, particularly ones that 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.

[0038] One particularly preferred combination of acids is thus the combination of oleic acid and 2-ethylhexanoic acid, which has a particularly beneficial effect on the solubility of the composition and enhanced ambient fluidity and liquid properties.

[0039] 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. [0040] The organometallic salt composition is typically prepared using the step of reacting the long chain carboxylic acid, for example oleic acid, with the copper, e.g. in the form of copper carbonate, 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. [0041] The optional short or medium chain carboxylic acid may be added after the formation of the intermediate salt, particularly in order to facilitate the formation of a final 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.

[0042] 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. [0043] 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 used in the invention are thus preferably derived from the reaction of monocarboxyl ic acids in the range C13 to C22 and copper carbonate.

[0044] As mentioned above, preferable organometallic salts are derived from unsaturated acids, such as linolenic, linoleic and oleic acids.

[0045] 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. [0046] In a preferred embodiment, the organometallic salt composition includes at least one unsaturated long-chain monocarboxyl ic acid, while any further monocarboxyl ic acids can be selected from either saturated or unsaturated ones. [0047] The activated complex, in turn, comprises a first metal component, a second metal component, and particles comprising a 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 improved friction and wear performance, particularly when particles, such as nanoparticles, are produced in- situ, to provide a lubricant additive composition, where the particles include the first metal component in metallic form. The second metal component participates in a redox reaction of the metal element in the first metal component.

[0048] It is particularly preferred when attempting to achieve the desired metal-plating characteristics, that one of the first and second metal components is a copper(ll) salt, this copper(ll) salt, preferably being the first metal component.

[0049] Preferably, the first metal component comprises gold, silver, copper, palladium, tin, cobalt, zinc, bismuth, manganese and/or molybdenum, more preferably copper and/or cobalt, even more preferably copper, most suitably copper(ll).

[0050] The second metal component preferably comprises tin, bismuth, zinc, and/or molybdenum, preferably tin, bismuth and/or zinc, more preferably tin, most suitably tin(IV).

[0051] Also, the second metal component can be added in the form of particles. Thus, it can be advantageous to include the first metal component, in metallic form, into particles including the second metal component. [0052] However, according to a preferred embodiment, particles, preferably nanoparticles, are formed from the first metal component in metallic form, in the presence of the second metal component, in the form of an inorganic salt.

[0053] The particles of the activated complexes, comprise the first metal component, and 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.

[0054] The particles of the activated complex preferably contain also 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. [0055] The surfactants or dispersants can be components that function as ligands. A ligand can be either a surfactant and/or a dispersant; examples are succinimide, poylethoxylated 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.

[0056] Further, at least one compound may be added to improve the solubility of the particles, e.g. epoxy resin of diethylene glycol or epoxidized dipropylene glycol. These preferred components are all typically added to the particles of the first metal component.

[0057] The nanoparticles of the combination of the organometallic salt composition and activated complex are preferably produced from the above- mentioned components by an electrochemical redox reaction. The thus produced nanoparticles typically have a size within the range of 25 to 50 nm.

[0058] In said combination of organometallic salt composition and activated complex, the weight ratio of the organometallic salt composition to the activated complex is preferably in the range of 10,000:1 to 1 :1, more preferably in the range of 100:1 to 10:1.

[0059] In addition to the above described nanoparticles, the present invention also relates to the use of an organometallic salt composition comprising a copper salt of one or more long chain monocarboxyl ic acid(s), in combination with an activated complex comprising a copper(ll) salt and a second inorganic metal salt, to produce oil soluble nanoparticles to act as metal-plating agent in lubricant applications, while also reducing friction and wear. [0060] Further, the invention relates to a metal-plating additive system comprising an organometallic salt composition comprising a copper salt of one or more long chain monocarboxyl ic acid(s), an activated complex comprising a copper(ll) salt and a second inorganic metal salt, as well as oil soluble nanoparticles formed from the metal salts of the activated complex.

[0061] Additionally, the invention relates to a lubricant additive composition, comprising an organometallic salt composition comprising a copper salt of one or more long chain monocarboxyl ic acid(s), an activated complex comprising a copper(ll) salt and a second inorganic metal salt, as well as oil soluble nanoparticles formed from the metal salts of the activated complex, optionally combined with further additive components.

[0062] 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.

[0063] 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 the examples below. Typical processes for obtaining activated complexes, as the ones referred to above are disclosed in further detail in WO2015/173421, hereby incorporated by reference.

[0064] When conducting the experiments of the below examples, it was discovered that the lubricant additive composition of the invention had a copper plating effect on steel metal. This discovery was relevant also for the nanoparticles of the invention, and raised the question about the impact of the metal-plating characteristics on performance of the lubricant additive composition. It was vital to know what influence each individual component, and combinations of components, in the activated complexes had on the behaviour of the additive composition.

[0065] Extensive experiments were conducted to better understand how the different components in the activated complexes function together, and in what way the reactivity and performance of the nanoparticles can be optimised. This was particularly important because it had been determined that the nanoparticles must display sufficiently strong metal-plating characteristics, as a prerequisite to significantly reduce friction and wear, when deployed in lubricants. [0066] The activated complexes were deconstructed in order to determine the function and influence of each component on the metal-plating characteristics. This involved taking different combinations of the various components and observing the impact on metal-plating performance. This provided a clearer understanding about how the different individual components act together in order to influence the metal-plating characteristics. It also provided insights about how the components interact together to establish an effective equilibrium between oil solution and metal surface film.

[0067] It was found that copper(ll) chloride in combination with any other component(s) is able to produce metal-plating. Certain additional components improved the metal-plating effect and some had a negative impact. The most tenacious metal film was obtained when all the tested activated complex components were included together.

[0068] The key findings from the activated complex deconstruction experiments were as follows:

(i) All components should be combined to produce a particularly tenacious metal-plating

(ii) Bimetallic (e.g. Cu(ii)/Sn(iv)) system is highly beneficial for effective metal plating

(iii) Sn(ii) does not facilitate metal plating

(iv) Reducing agent is preferred for robust metal-plating

(v) Expoxy resin is preferred for comprehensive metal-plating

(vi) Succinimide dispersant facilitates the control of the degree of metal-plating

[0069] Therefore, although the minimum requirement for the activated complex is that it comprises two metal salts, one being a copper(ll) salt, several other components can be beneficial to use, such as reducing agent, solubility- enhancing agent (e.g. epoxy resin) and/or dispersant (e.g. succinimide). [0070] The detailed results from these experiments are given in the Example 6. [0071] These experiments demonstrate that the particles must not only be oil soluble, but also be capable of participating in an effective metal-plating process, to form a consistent, uniform and durable film on the metal surface. This involves particles being released from the micelles in the colloid and then migrating and depositing on the metal surface. They then actively reorganize and self-assemble themselves, in a dynamic and collective effort, to form an adsorbed film. This process is facilitated by van der Waals forces between the nanoparticles.

[0072] The activated complex deconstruction experiments also demonstrate that a tailored and deliberate, mix and balance, of the different individual components is highly beneficial, to facilitate the formation of a tenacious and comprehensive film, as part of the metal-plating process.

[0073] It is apparent that an effective metal-plating process requires an equilibrium to be established between the particles in oil solution, and in the metal surface film. This dynamic equilibrium is brought about by particles, in micelles within the oil colloid system, being progressively released in a controlled manner, and then migrating to the metal surface, and form an adsorbed film.

[0074] Another factor that influences the effectiveness of the adsorbed layer is film thickness. This is controlled by the equilibrium between the rates of adsorption and desorption of the particles onto the metal surface. The microstructure of the adsorbed film is a result of the balance of the intermolecular energy between particles in the adsorbed film and also the intramolecular energy between the particles and the metal surface (and sub-surface).

[0075] Another factor to take into account is the durability of the adsorbed film, which is influenced by the mechanical interactions of the film with sliding metal surfaces. The efficacy is also related to the frictional characteristics of the film’s outer surface. [0076] It is evident that a tribofilm on the metal surface should be tenacious and comprehensive in order to be effective in reducing friction and wear. The film should not be blistered or flaky; uneven or irregular; patchy or sparse. It should in turn be capable of repairing itself when wear of the adsorbed film occurs, due to mechanical interactions. This will maintain and sustain a robust protective layer on the metal surface.

[0077] By utilising the experiments findings, it has been unexpectedly found that when the organometallic salt compositions described herein, are combined with activated complexes also described herein, to produce nanoparticles made by the in-situ process further described herein, that superior metal-plating characteristics are achieved, compared to the prior art. Robust metal-plating and film forming attributes can also deliver strong friction and wear performance in the lubricant additive compositions.

[0078] It has also been surprisingly and unexpectedly found that the friction and wear performance of lubricants can be significantly further improved, by using an increased amount of the activated complex, reacted with the copper organometallic salt compositions. This boost in performance is not linear or proportional to the quantity of nanoparticles. It indicates that an important synergy exists, between the activated complex and the copper organometallic salt compositions, to achieve an exceptional further improvement in the reduction of friction and wear. [0079] A typical ratio of organometallic salt composition to activated complex is within the range of 1/100 - 5/100, while the combination exhibits improved friction and wear performance using a ratio of 7/100 - 10/100.

[0080] It was further found that the friction and wear performance was significantly improved even more, and to an unexpected extent, with extra boosted compositions of the present invention, which contained an addition of oleic acid.

[0081] This boosted composition typically contained 1-2 wt-% of added oleic acid. [0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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

[0088] In a general procedure, 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 8-9 wt%. The reaction typically proceeds at a temperature of at least 60°C until the salt is in liquid form.

[0089] In a more precise procedure of this example, 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 8-9 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 an activated complex and nanoparticles according to the present invention

[0090] The preparation of the activated complex involves a three-step process.

[0091] 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.

[0092] 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.

[0093] 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 3: Preparation of a lubricant additive composition according to the present invention

[0094] A lubricant additive composition of the present invention was prepared by mixing the activated complex from Example 2 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 4: Preparation of a boosted lubricant additive composition according to the present invention

[0095] A boosted lubricant additive composition of the present invention, with superior friction and wear performance, was prepared by mixing the activated complex from Example 2 with the copper-based organometallic salt composition from example 1. The relative amount of the activated complex in the additive composition was increased. It was carried out by slowly adding the activated complex (about 7 g) to the copper oleate (about 93 g) 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: Preparation of a further boosted lubricant additive compositions according to the present invention

[0096] Further boosted lubricant additive compositions of the present invention, with superior friction and wear performance, were prepared by mixing the activated complex from Example 2 with the copper-based organometallic salt composition from example 1. The relative amount of the activated complex in the additive composition was increased. It was carried out by slowly adding the activated complex (about 7 g) to the copper oleate (about 93 g) in a glass-lined vessel fitted with a stirrer and heating capability.

Example 5a

[0097] Then in one case, oleic acid was also added (about 1 g) to the above mixture. The temperature of the mixtures 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 5b

[0098] Then in another case, oleic acid was also added (about 2 g) to the above mixture. The temperature of the mixtures 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 6: Tribological effects of the nanoparticles produced with the organometallic salt compositions

[0099] The tribological effects of the additive compositions containing nanoparticles, prepared in Examples 3 and 4, were demonstrated in tribology tests on a ball-on-three-plates system.

[00100] The compositions were added to Chevron Taro 30 DP 40 in concentrations of 0.3%, 1% and 3% and heated in the range 60°C to 70°C under stirring for 15 min. The homogeneous oil mixtures were allowed to cool at ambient conditions. The samples were then tested in a tribometer using an Anton Paar rotational rheometer.

[00101] The measurement starts with a running-in phase to ensure stable measuring conditions can be established. This running-in phase is done at 1200 rpm for 30 minutes. After the running-in phase is complete, the friction behaviour is measured in the “Striebeck phase” during the next 10 minutes. The measuring regime starts at 0 rpm and the speed increases during the 10 minutes to 3000 rpm. The normal force is 6 N and the temperature 100°C throughout the measurement. Wear is measured by analysing the wear scars on the plates with optical microscope and imaging software after friction analysis.

[00102] The following conditions were used for the friction and wear tests:

[00103] The results of this testing are given in Tables 1 to 4. Table 1 - Friction behaviour of Example 3

Table 2 - Wear behaviour of Example 3

Table 3 - Friction behaviour of Example 4

Table 4 - Wear behaviour of Example 4

composition

Table 5 - Friction behaviour of Example 5a

Table 6 - Wear behaviour of Example 5a

Table 7 - Friction behaviour of Example 5b

Table 8 - Wear behaviour of Example 5b

[00104] From the tribology measurements in Tables 1 through 8, it became apparent that the composition of the present invention Example 3 has an advantageous impact on the friction and wear behaviour. It was also shown that the friction and wear performance was significantly improved further, to an unexpected extent, with the boosted composition of the present invention,

Example 4. It was further shown that the friction and wear performance was significantly improved even more, to an unexpected extent, with extra boosted compositions of the present invention, which contained an addition of oleic acid, Example 5.

Example 7: Metal-plating experiments with various components used in the activated complex

[00105] Experiments were conducted to better understand how the different components in the activated complexes function together to influence metal-plating characteristics. This involved taking different combinations of the various components in the activated complex and observe the impact on metal-plating performance. Test samples were prepared by simple mixing the different components together. A small steel metal plate was then submerged half-way into the sample, and it was allowed to stand for 6 days. The plate was the removed from the sample and examined for any kind of plating (copper plating). The results are presented in Table 9.

Table 9 - Results from activated deconstruction experiments on metaplating effects

[00106] The results in Table 5 with samples 1 to 7 indicate that copper(ll) chloride is able to form metal plating in combination with any other component(s). However, there are significant variations in the type and extent of metal-plating obtained. Sample 16, where all the components in the activated complex were present, gave the most comprehensive and tenacious metal film.

[00107] The results with samples 8 to 12 demonstrate that tin(IV) chloride cannot cause metal-plating, without copper(ll) chloride being present. However, when tin(IV) chloride is also present, in samples 13 to 16, there is an even stronger metal-plating effect than with only copper(ll) chloride alone. There is clearly a synergistic metal-plating effect with the bimetallic salt system. In contrast, replacing tin(IV) chloride by tin(ll) chloride in sample 17 gave reduced metal plating. The results for samples 18 and 19 with copper oleate again demonstrate the importance of the bimetallic salt system. Sample 20, that contains only copper oleate, but without the activated complex, gave no metal-plating at all. This demonstrates the crucial role of the activated complex in the metal-plating effect. [00108] The overall conclusion is that all the components in the activated complex play a critical role in the metal-plating process, with or without copper oleate. Some components in the activated complex are able to facilitate metal plating, but a superior metal-plating effect, with a homogeneous and tenacious film, is only achieved by the combination of all the components. It is clear that all of the components play an important role in metal-plating and film formation. Industrial Applicability

[00109] The present compositions can be used to reduce friction and wear. [00110] In particular, the use of the lubricant additive compositions as prepared according to the invention is beneficial in passenger car and heavy-duty engines, as well as a wide variety of driveline, industrial, and off-highway applications.

Citation List

WO 2017/005967 WO 2015/173421

Claims

1. Nanoparticles suitable for use in lubricants, characterized in that they have been prepared from an activated complex comprising a copper(ll) salt and one or more further inorganic metal salt(s), and combined with an organometallic salt composition comprising a copper salt of one or more long chain monocarboxyl ic acid(s).

2. The nanoparticles of claim 1 wherein the weight ratio of the organometallic salt composition to the activated complex is within the range of 10,000:1 to 1 :1, preferably in the range of 100:1 to 10:1.

3. The nanoparticles of claim 1 wherein the long chain carboxylic acid is an unsaturated acid.

4. The nanoparticles of claim 1 wherein the long chain carboxylic acid is linolenic, linoleic or oleic acid, preferably oleic acid.

5. The nanoparticles of claim 1 wherein the copper salt of the one or more long chain carboxylic acid is copper oleate.

6. The nanoparticles of claim 1 wherein the organometallic salt composition comprises the salts of two different long chain monocarboxyl ic acids.

7. The nanoparticles of claim 1 wherein the organometallic salt composition is prepared using the step of reacting a long chain carboxylic acid with copper carbonate.

8. The nanoparticles of claim 7 wherein the molar ratio of the carboxylic acid to the copper of the carbonate reactant is in the range 1 :1 to 20:1.

9. The nanoparticles of claim 1 wherein the activated complex comprises a first metal component, a second metal component, and particles comprising a first metal component, one of the first and second metal components being a copper(ll) salt, preferably the first metal component.

10. The nanoparticles of claim 9 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, most suitably copper(ll).

11. The nanoparticles of claim 9 wherein the second metal component comprises tin, bismuth, zinc, and/or molybdenum, preferably tin, bismuth and/or zinc, more preferably tin.

12. The nanoparticles of claim 1 having a size within the range of 25 to 50 nm.

13. The nanoparticles of claim 1 having been produced by an electrochemical redox reaction between the two metallic salts of the activated complex, and subsequent addition of the organometallic salt composition, optionally followed by a further addition of 1-2 wt-% of oleic acid.

14. Use of an organometallic salt composition comprising a copper salt of one or more long chain monocarboxyl ic acid(s), in combination with an activated complex comprising a copper(ll) salt and a second inorganic metal salt, to produce oil soluble nanoparticles to act as metal-plating agent in lubricant applications, while also reducing friction and wear.

15. A metal-plating additive system comprising an organometallic salt composition comprising a copper salt of one or more long chain monocarboxyl ic acid(s), in combination with an activated complex comprising a copper(ll) salt and a second inorganic metal salt, forming oil soluble nanoparticles.

16. A lubricant additive composition, comprising an organometallic salt composition comprising a copper salt of one or more long chain monocarboxyl ic acid(s), in combination with an activated complex comprising a copper(ll) salt and a second inorganic metal salt, forming oil soluble nanoparticles, and optionally comprising further additive components.