Ionic liquid composition

Abstract

To provide an ionic liquid composition which limits chemical degradation of hydrocarbonaceous liquids due to nitrogen dioxide contamination in high-temperature operation, and reduces friction or wear, or both, in the contact between mechanical parts.SOLUTION: An ionic liquid comprises: (i) one or more nitrogen-free organic cations each comprising a central atom or ring system bearing a cationic charge and multiple pendant hydrocarbyl substituents; and (ii) one or more halogen- and boron-free organic anions each comprising an aromatic ring bearing a carboxylate functional group and a further heteroatom-containing functional group, these functional groups being conjugated with the aromatic ring and this conjugated system bearing an anionic charge, and the aromatic ring additionally bearing one or more hydrocarbyl substituents. Also provided is an additive concentrate for hydrocarbonaceous liquids, comprising the ionic liquid and a carrier liquid compatible with the ionic liquid.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ionic liquid composition useful as an additive to hydrocarbon liquids. The ionic liquid has been found to be particularly advantageous in limiting the chemical decomposition of hydrocarbon liquids due to nitrogen dioxide contamination during high-temperature operation. Adding an amount of the ionic liquid to the hydrocarbon liquid inhibits the nitrification of the hydrocarbon liquid by nitrogen dioxide, which initiates decomposition. The ionic liquid also has the advantage of reducing friction, wear, or both in contact between mechanical parts lubricated by the hydrocarbon operating fluid, and when blended into engine lubricating oil, it improves the balance of properties and slows down the increase in acidification, which also promotes the chemical decomposition of the oil. [Background technology]

[0002] Hydrocarbon fluids are used as operating fluids in a wide range of mechanical applications, particularly as lubricants, protective agents, hydraulic fluids, greases, and heat transfer fluids for engineering components and equipment. The composition and properties of such fluids are selected according to their intended application, and because high molecular weight hydrocarbon species are readily available, these fluids can be formulated for operation at high temperatures, especially above 100°C, where aqueous fluids are unsuitable. Such hydrocarbon liquids can typically be obtained from petroleum or synthetic sources, or from biomaterial processing. In particular, hydrocarbon lubricants and hydraulic fluids are becoming standard in a variety of applications, such as automotive fluids like engine lubricants and power transmission fluids. The fundamental performance characteristics of a working fluid refer to its ability to maintain beneficial properties throughout its operational life. Operation under harsh conditions places physical and chemical stress on the fluid, and limiting the resulting fluid decomposition is a major consideration when selecting and formulating the fluid. Working fluids typically need to meet many performance requirements in development and certification related to maintaining their operational life, and candidate fluids are subjected to testing under relevant operating conditions that promote decomposition.

[0003] High operating temperatures and the presence of chemically reactive contaminants increase the demands on hydrocarbon liquids. High bulk liquid temperatures and the accumulation of reactive contaminants accelerate decomposition reactions, severely reducing operational life and potentially preventing the liquid from adequately operating or protecting surrounding machinery. In this technical field, there is a general need to improve the operational life of hydrocarbon fluids, particularly lubricants, operating at elevated bulk temperatures by enhancing their resistance to chemical decomposition in bulk under operating conditions. Furthermore, in mechanisms that include movable parts immersed in or coated with hydrocarbon fluids for forced contact, there is a general need to improve wear resistance and / or reduce friction. The decomposition of hydrocarbon liquids, particularly at high bulk temperatures, has traditionally been referred to as "oxidation" in the art. This oxidation is based on the conventional understanding that the chemical reactions causing the decomposition are fundamentally involved in the reaction of aged hydrocarbon species with oxygen via a free radical pathway that includes peroxides formed in situ during operation. As these aged hydrocarbon species accumulate over time, the liquid decomposes, degrading the properties and operating performance of the bulk liquid. Various additives, traditionally called "antioxidants," have been proposed in the art. Antioxidants inhibit this oxidation pathway and include hydrocarbon-soluble hindered phenols and amines, slowing the accumulation of oxidative decomposition resulting from liquid aging during operation.

[0004] However, the applicant's research has characterized an alternative chemical decomposition pathway that occurs in newly prepared hydrocarbon fluids free from aging components. This decomposition begins not by reaction with oxygen or peroxides, but by the direct chemical action at high temperatures of nitrogen dioxide incorporated into the liquid by contamination during operation. Nitrogen dioxide initiates chemical decomposition via nitrification with the hydrocarbon liquid, a reaction that has been shown to significantly destroy the liquid in a process that begins while the liquid is still fresh. Nitrogen dioxide can also oxidize to nitric acid in the bulk liquid environment, causing acidic attack on the liquid and the machinery designed to protect it. Consequently, there is a particular need to limit the decomposition effect of nitrogen dioxide contamination in hydrocarbon liquids at high temperatures. This decomposition effect can cause decomposition early in the operational life and may also exacerbate problems caused by conventional oxygen-derived oxidation. Such contamination by nitrogen dioxide occurs when hydrocarbon fluids are exposed to a source of nitrogen dioxide during operation. Nitrogen dioxide (NO2) is formed, for example, during combustion reactions, frequently via the intermediate formation of nitrogen oxide (NO), through the reaction of naturally occurring nitrogen and oxygen in the air when exposed to high temperatures. Nitrogen dioxide is also a combustion product of petroleum or many bio-based fuels. Both petroleum and bio-based fuels contain large amounts of bound nitrogen, which is released as nitrogen dioxide during complete combustion and can be incorporated into the operating fluid that comes into contact with it. Such exposure occurs particularly frequently in combustion devices, such as internal combustion engines lubricated by hydrocarbon fluids that generate nitrogen dioxide and are exposed to exhaust gases; and especially in crankcase lubricants, which are present on the engine surface in the cylinder region and in direct contact with exhaust gases, and also induce nitrogen dioxide in the crankcase oil reservoir beyond the piston rings via blow-through exhaust gases, where nitrogen dioxide is incorporated along with the lubricant.

[0005] Modern engine and aftertreatment developments aimed at improving engine fuel efficiency and minimizing carbonaceous particulate matter emissions have resulted in higher combustion temperatures, leading to the generation of high levels of nitrogen dioxide in engine exhaust gases through an effect known as "NOx-particulate exchange." Higher engine temperatures also lead to higher bulk lubricant operating temperatures, creating conditions for increased chemilysis initiated by nitrogen dioxide. Furthermore, modern designs focus on improving the fuel efficiency of internal combustion engines. Consequently, the design incorporates a larger gap between the piston rings and the back of the cylinder to reduce internal friction. This results in an increased amount of exhaust gas being injected into the crankcase by the piston rings, leading to self-propelled engines where the exhaust gas is incorporated into the bulk engine lubricant. Consequently, hydrocarbon fluids contaminated with nitrogen dioxide during high-temperature operation face specific challenges due to chemical nitrification pathways that act early in the fluid's life and are not initiated by conventional hydrocarbon oxidation. This challenge is particularly severe in the case of engine lubricants, where various engineering measures increase the degree of nitrogen dioxide uptake into the bulk lubricant at high operating temperatures. The resulting nitrification pathway is particularly pronounced at bulk fluid temperatures of 60–180°C and particularly severe at bulk fluid temperatures of 110–160°C, which is even more pronounced in crankcase lubricants used under harsh operating conditions or in modern high-temperature engine designs, and therefore the applicant believes that the impact of this chemical pathway on lubricant degradation is exacerbated.

[0006] The present invention provides a solution to this problem through the formulation of a predetermined ionic liquid additive having a specific ability to inactivate nitrogen dioxide and thereby inhibit nitrification of hydrocarbon liquids. Through this action, the predetermined ionic liquid additive limits the chemical decomposition that initiates nitrification and improves the operational life of the hydrocarbon liquid. One of the physical consequences of chemical decomposition in hydrocarbon-based operating fluids is an increase in fluid viscosity during operation. This increase in viscosity can cause the fluid to fail to meet specified viscosity standards, potentially leading to premature fluid replacement. The ionic fluid formulations defined in this invention further offer the advantage of limiting the viscosity increase during operation and mitigating the resulting limitation of the operating life. Many hydrocarbon fluids, particularly lubricants such as engine lubricants, are formulated to control the increase in acidity caused by oxidation processes resulting from the formation of acid species in the liquid, and the subsequent acidic corrosion or wear. Therefore, controlling the accumulation of acid species over the service life is a further advantage for such fluids. The formulation of ionic fluids as defined in this invention provides the further advantage of improved control of acid accumulation in the liquid, and this additional advantage also provides the compounder with the ability to prepare an improved operating fluid.

[0007] Reducing friction and wear between contact surfaces of mechanical devices remains a persistent challenge for engineers, especially under harsh physical conditions such as high temperature and pressure. Many such systems are lubricated or protected by hydrocarbon fluids, which work to provide resistance to such wear and facilitate the suppression of friction during operation. The ionic fluids of the present invention offer the further advantage of reducing friction and / or wear at mechanical contact surfaces and can be formulated as additives for this purpose, separately from or in addition to their use in deactivating nitrogen dioxide contamination. Thus, the ionic fluids defined in the present invention combine advantages over conventional antioxidants and other ionic fluids previously considered in the art for use as additives in hydrocarbon fluids, broadening the range of properties that enhance operating fluid performance and operational life.

[0008] U.S. Patent No. 8,278,253 describes enhancing the oxidation resistance of lubricating oil by adding an additive amount of ionic solution. From the description of this invention and Example 1, it is clear that the method focuses on reducing oxidation by hydroperoxides, rather than the nitrogen dioxide-derived decomposition that the present invention addresses. A wide variety of cations and anions are separately listed as possible components of the ionic solution, of which the preferred anions and all anions in the examples are fluorine-containing non-aromatic structures, most of which further contain boron. This document does not disclose the specific cation-anion combinations required for the ionic solution of the present invention, nor does it teach the advantages of inhibiting nitrogen dioxide-induced nitrification of new, unaged oils, or the advantages of improving other relevant properties. International Publication No. 2008 / 075016 relates to ionic liquid additives for non-aqueous lubricant compositions. These ionic liquid additives are intended to reduce wear and / or modify frictional properties and are defined as non-halide or non-aromatic ionic liquids. Here, anion A - It contains at least one oxygen atom and has an ionic head group bonded to at least one alkyl group or alicyclic hydrocarbyl group. This document also does not disclose the specific cation-aromatic anion combination required for the ionic solution of the present invention, nor does it teach the advantages of inhibiting nitrification of new, unaged oils by nitrogen dioxide, and the advantages of improving other related properties.

[0009] International Publication No. 2013 / 158473 relates to lubricant compositions containing ionic liquids and methods for using such compositions, with the aim of minimizing deposit and sludge formation in internal combustion engines. The study example focuses on high-temperature deposit formation that occurs after pre-test aging of lubricating oil, in which a new oil is blended with a large amount of used lubricant, a dry air / nitrogen dioxide mixture is sprayed thereon, and then the deposit formation process is carried out on a metal surface heated to at least 200°C, preferably 320°C, while being exposed to simulated exhaust gas. The ionic liquid contains a set of nitrogen-containing cations, an anion represented by the structure YCOO(-) where Y is alkyl or aromatic, preferably an alkyl or alkoxyl functional group with 1 to 50 carbon atoms, or a benzene group, or an alkylated benzene group where the alkyl group(s)(single or multiple) have 1 to 10 carbon atoms. This document does not disclose a specific cation-anion combination of the ionic solution formulated in the present invention, nor does it teach the advantages of inhibiting nitrification of new, unaged oils by nitrogen dioxide at bulk liquid temperatures below 200°C, or the advantages of improving other related properties.

[0010] U.S. Patent No. 2010 / 0187481 relates to the use of ionic liquids to improve the lubricating effect of synthetic oils, mineral oils, or natural oils. This invention discloses that the resulting lubricant composition is protected from thermal and oxidative attack. The ionic liquid is said to be superior to phenolic or amine antioxidants as a thermal and oxidative stabilizer because it is soluble in organic systems or has an extremely low vapor pressure. Preferred anions for the ionic liquid are highly fluorinated due to their high thermal stability, such as bis(trifluoromethylsulfonyl)imide, and there is no mention or statement regarding the control of decomposition by nitrogen dioxide. The present applicant has now found that by formulating an ionic liquid consisting of a predetermined cation and a polyfunctional aromatic anion containing no boron and halogen in an additive amount, the nitration of hydrocarbon liquids due to nitrogen dioxide pollution at high temperatures can be inhibited, and a new method is provided that can limit the chemical decomposition of hydrocarbon liquids even when they are new and not aged by operation. By this method, the lifespan of operating liquids that encounter such pollution is extended. The ionic liquid also serves to reduce friction and / or wear in mechanical systems operating with hydrocarbon liquids, providing further advantages over the prior art as detailed herein.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Patent Document 10

Patent Document 11

Patent Document 12

[0012] [Non-Patent Document 1] Coultas, DR "The Role of NOx in Engine Lubricant Oxidation," SAE Technical Paper, 2020, No. 2020-101427, Digital Object Identifier (doi): 10.4271 / 2020-01-1427 [Non-Patent Document 2] "Engine Oil Licensing and Certification System ("ELOCS")," Industry Services section, published by the American Petroleum Institute (API), December 1996, 14th edition, Appendix 1, December 1998. [Non-Patent Document 3] "CHEMICAL AND ENGINEERING NEWS", 1985, No. 63 (5), 27 [Overview of the project]

[0013] In a first aspect, the present invention provides an ionic solution comprising the following: (i) One or more nitrogen-free organic cations comprising a central atom or ring system having a cationic charge and a plurality of pendant hydrocarbyl substituents, and (ii) One or more organic anions that do not contain halogens or boron, each containing a carboxylate functional group and an aromatic ring having a functional group further containing a heteroatom, wherein these functional groups are conjugated with the aromatic ring, this conjugated system has an anionic charge, and the aromatic ring further has one or more hydrocarbyl substituents.

[0014] In a second aspect, the present invention provides an additive concentrate for hydrocarbon liquids, comprising the ionic liquid of the first aspect and a carrier liquid compatible with the ionic liquid. In a third aspect, the present invention provides a hydrocarbon liquid containing the ionic liquid of the first aspect or the additive concentrate of the second aspect such that the amount of the ionic liquid is a maximum of 5.0% by mass per unit mass of the hydrocarbon liquid. In a fourth aspect, the present invention provides the use of the ionic solution of the first aspect or the additive concentrate of the second aspect as an additive for hydrocarbon liquids to chemically inactivate nitrogen dioxide incorporated into the hydrocarbon liquid. In the use of the fourth embodiment, the ionic solution consequently inhibits the formation of hydrocarbon nitrate esters and extends the operational life of the hydrocarbon solution.

[0015] In a fifth aspect, the present invention provides the use of the ionic solution of the first aspect or the additive concentrate of the second aspect as an additive for hydrocarbon liquid lubricants to reduce the coefficient of friction of the lubricant, improve its resistance to mechanical wear, or both. In the use of the fifth aspect, the ionic solution is preferably also used to chemically deactivate nitrogen dioxide incorporated into the hydrocarbon lubricant, and more preferably to inhibit the increase in the total acid number measured according to the ASTM standard (ASTM) D664 test method in the hydrocarbon lubricant during operation. In a sixth aspect, the present invention provides a method for extending the operational life of a hydrocarbon liquid lubricant that has been contaminated with nitrogen dioxide during operation. The method comprises adding the ionic solution of the first aspect or the additive concentrate of the second aspect to the hydrocarbon lubricant before operation, the amount of which is effective in subsequently reducing the coefficient of friction of the lubricant or improving its resistance to mechanical wear, or effective in chemically inactivating the nitrogen dioxide incorporated into the hydrocarbon liquid lubricant, thereby inhibiting the formation of hydrocarbon nitrate esters in the hydrocarbon liquid lubricant, or effective for both. In the method of the sixth embodiment, it is preferable that the ionic solution or additive concentrate is effective in both chemically inactivating nitrogen dioxide incorporated into the lubricant and reducing the coefficient of friction of the lubricant to improve resistance to mechanical wear.

[0016] The following describes preferred embodiments of these various aspects of the present invention. This specification also refers to the following drawings. [Brief explanation of the drawing]

[0017] [Figure 1] This figure shows the nitrification peak height in the ionic liquid-containing lubricating oil composition during the T13 engine test, which is detailed in Research Example 2 below; [Figure 2] This figure shows the acid value peak height of the ionic liquid-containing lubricating oil composition during the T13 engine test, which is detailed in Research Example 2 below; [Figure 3] This figure shows the increase in kinematic viscosity of the ionic liquid-containing lubricating oil composition during the T13 engine test, which is detailed in Research Example 2 below; [Figure 4] This figure shows the results of a friction coefficient test using a high-frequency reciprocating rig (HFRR) for the ionic liquid-containing lubricating oil composition of the present invention, which is detailed in Research Example 3 below. [Figure 5] This figure shows the results of a friction coefficient test using the TE-77 test method for a lubricating oil composition containing the ionic liquid of the present invention, which is described in detail in Research Example 3 below. [Figure 6]This figure shows the results of an abrasion mark volume test using the MTM-R test method for a lubricating oil composition containing the ionic solution of the present invention, which is described in detail in Research Example 3 below. [Figure 7] This figure shows the results of a wear mark volume test using a high-frequency reciprocating rig (HFRR) for a lubricating oil composition containing the ionic liquid of the present invention, which is detailed in Research Example 3 below. [Modes for carrying out the invention]

[0018] It is understood that the various essential components used, as well as optional and conventional components, may react under the conditions of formulation, storage, or use, and that the present invention also provides products that can or may be obtained as a result of any such reaction. Furthermore, it is understood that the upper and lower limits of the quantities, ranges, and ratios described herein may be combined independently. Furthermore, it is understood that preferred features of each aspect of the present invention are to be considered preferred features of any other aspect of the present invention. Accordingly, preferred and more preferred features of one aspect of the present invention may be independently combined with other preferred and / or more preferred features of the same or different aspects of the present invention.

[0019] The importance of nitrogen dioxide decomposition in new lubricants at high temperatures was recently reported by the applicant in a paper cited as Coultas, DR, "The Role of NOx in Engine Lubricant Oxidation," SAE Technical Paper, 2020, No. 2020-101427, digital object identifier (doi): 10.4271 / 2020-01-1427. In its preface, the paper states that "the main mechanism by which NOx decomposes lubricants is through its involvement in free radical nitro oxidation reactions." The following equation shows that nitrogen dioxide initiates the process by extracting protons from liquid hydrocarbon species, triggering a series of reactions involving other species, resulting in the chemical decomposition of the hydrocarbon liquid. Nitrogen dioxide also plays a significantly important role in this decomposition pathway by reacting with RO· radicals to form hydrocarbon nitrate esters represented by the formula RONO2. These hydrocarbon nitrate esters accumulate in the lubricant, forming a reservoir of nitrate esters. As the operating temperature increases, these nitrate esters gradually dissociate, releasing the captured RO radicals, forming a characteristic "volcanic curve" of nitrate esters as illustrated in Figure 14 of this paper. This rapid dissociation from nitrate esters to free radicals accelerates the chemical breakdown of hydrocarbon species in the liquid. This series of reactions of nitrogen dioxide, including both the initial proton extraction and the subsequent dissociation of the nitrate esters formed, is referred to herein as "nitrification" of hydrocarbon liquids.

[0020] The applicant determined that the initiation of this nitrification reaction pathway via proton extraction by nitrogen dioxide, and the formation and dissociation of the nitrate ester reservoir in the further action of nitrogen dioxide, are functions of the elevated bulk fluid temperature. The initiation of the nitrification reaction sequence proceeds at 60°C and is accelerated at temperatures above 80°C. Nitrate ester formation is significantly constructed in the range of 110–180°C, and the rate of nitrate ester dissociation increases from 130°C. In the temperature range of 110–160°C, the formation and dissociation of nitrate ester are most pronounced, and the chemical decomposition of the hydrocarbon liquid is further accelerated. Therefore, the tendency of the bulk fluid (oil reservoir) temperature to rise (to temperatures above 130°C) in modern engine lubricants increases the actual amount of nitrogen dioxide contamination, making these engine lubricants more susceptible to such decomposition forms. Without being bound by any particular theory, the applicant believes from technical investigations that the ionic solution formulated in this invention has a particularly favorable affinity for nitrogen dioxide, which, when present as a contaminant in a hydrocarbon liquid, causes inactivation. As a result, it inhibits nitrogen dioxide from reacting with the hydrocarbon liquid species and from initiating decomposition via proton extraction to initiate the nitrification reaction pathway. Furthermore, it inhibits nitrogen dioxide from reacting to form nitrate esters that produce a volcanic curve at higher temperatures and from ejecting radicals that lead to further decomposition. In particular, as detailed herein, the applicant has demonstrated the affinity of the ionic solution formulated in the present invention for nitrogen dioxide and shown that the ionic solution is superior to other ionic solutions in the prior art. The applicant has also demonstrated that the ability of the present invention can be considerably improved to inhibit nitrification of hydrocarbon liquids and inhibit the increase in bulk liquid acidity over time under operating conditions subject to high temperatures.

[0021] The applicant has also found that the ionic liquid of the present invention is particularly advantageous for reducing friction and / or wear in mechanical systems lubricated with hydrocarbon liquids, as demonstrated by its ability to reduce the coefficient of friction of lubricants, or for improving the resistance of the hydrocarbon liquid to mechanical wear at the contact surfaces of the mechanical equipment under its operation. While this advantage of the ionic liquid can be utilized on its own, it is advantageous when combined with the ionic liquid's ability to inactivate nitrogen dioxide contamination, thereby inhibiting the nitrification and resulting chemical decomposition of the hydrocarbon liquid. Therefore, the ionic solution of the present invention has advantages over conventional ionic solution additives in that it controls nitrification and resulting decomposition in hydrocarbon solutions through the inactivation of nitrogen dioxide contamination. On the other hand, the ionic solution also improves the mechanical properties of hydrocarbon solutions by reducing friction and / or wear at the contact surfaces of machinery and equipment operating with the ionic solution. It is believed that these characteristics can be combined in this way by selecting the cations and anions that constitute the ionic solution of the present invention, and this combination improves the balance of the properties of the ionic solution. The advantages of the operating conditions for the ionic solutions formulated in this invention will be demonstrated in the research examples described later in this specification.

[0022] Ionic solution according to the first aspect of the present invention Ionic solutions have conventionally been understood as ionic compounds consisting of one or more cation-anion pairs, existing in a liquid physical form at industrially beneficial temperatures. The present invention provides a predetermined ionic solution comprising the following: (i) One or more nitrogen-free organic cations comprising a central atom or ring system having a cationic charge and a plurality of pendant hydrocarbyl substituents, and (ii) One or more organic anions that do not contain halogens or boron, each comprising a carboxylate functional group and an aromatic ring having a functional group further comprising a heteroatom, wherein these functional groups are conjugated with the aromatic ring, the conjugated system has an anionic charge, and the aromatic ring further comprises one or more hydrocarbyl substituents.

[0023] One or more cations (i) contain one or more hydrocarbyl substituents that carry a cationic (positive) charge, provide organic affinity to the ionic solution, and allow the ionic solution to be easily mixed with hydrocarbon bulk liquids. In this specification, the term "hydrocarbyl substituent" refers to a group comprising a hydrogen atom and a carbon atom, each directly bonded to the remainder of the compound via the carbon atom. The group may also contain one or more atoms other than carbon and hydrogen (i.e., heteroatoms), provided that they do not affect the group's essential hydrocarbyl properties, i.e., the oxygen, nitrogen, and sulfur atoms; such groups include amino, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy groups. However, preferably, unless otherwise specified, the hydrocarbyl group is basically composed of a hydrogen atom and a carbon atom, more preferably composed of a hydrogen atom and a carbon atom. Preferably, the hydrocarbyl group is an aliphatic hydrocarbyl group or contains an aliphatic hydrocarbyl group. The term "hydrocarbyl" encompasses the term "alkyl" as conventionally used herein. Preferably, the term "alkyl" refers to a radical of carbon and hydrogen (e.g., C1-C12 30 For example, C4~C 20This means an alkyl group. Alkyl groups in a compound are usually directly bonded to the compound via carbon atoms. Unless otherwise specified, alkyl groups may be linear (i.e., unbranched) or branched, and may be cyclic, acyclic, or partially cyclic / acyclic. Alkyl groups may include linear or branched acyclic alkyl groups. Typical examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, dimethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, and triacontyl. A substituted alkyl group is an alkyl group in which hydrogen or carbon is substituted with a heteroatom (i.e., not H or C) or a heteroatom-containing group. The term "substituted" generally means that hydrogen atoms have been replaced with carbon atoms or heteroatom-containing groups.

[0024] Each cation (i) in the ionic solution does not contain nitrogen. This composition of the ionic solution has been found to be advantageous in the present invention. Preferably, each cation (i) in the ionic solution consists of a tetrahydrocarbyl-substituted central atom or ring system having a cationic charge. Most preferably, each cation (i) in the ionic solution is a phosphorus-containing cation. In this embodiment, each cation (i) is preferably an alkyl-substituted phosphonium cation, ideally a tetraalkyl-substituted phosphonium cation. Suitable alkyl groups as substituents for such phosphonium cations include linear or branched alkyl groups having 1 to 28 carbon atoms, for example, 4 to 28, preferably 6 to 28, and more preferably 6 to 14. Particularly suitable alkyl substituents for such phosphonium cations include hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl groups, with n-alkyl groups being particularly preferred here. At least one of the alkyl substituents preferably contains at least 10 carbon atoms and is selected from the above examples. Most preferably, each cation (i) is a trihexyltetradecylphosphonium cation, i.e., a cation supporting three hexyl groups and one tetradecyl group as substituents, these substituents preferably being linear alkyl groups. Such anions are sometimes known in the art by the abbreviation "P66614", where the numbers represent the number of carbon atoms in the three hexyl groups and one tetradecyl group (6, 6, 6, 14).

[0025] One or more anions (ii) contain an aromatic ring having at least two substituted functional groups, each containing a heteroatom, where these functional groups are conjugated to the aromatic ring, and at least one of the functional groups is a carboxylate group, and this conjugated system has an anionic (negative) charge. In this specification, the term “conjugated” is used in the conventional chemical sense, where one or more p-orbitals of one or more atoms contained within each of these functional groups are coupled to the p-orbitals of adjacent aromatic rings, and are involved in the delocalized electron cloud of the aromatic ring. Anions with such a configuration are thought to have a particularly high affinity for nitrogen dioxide and can bind to nitrogen dioxide in such a way that they significantly reduce the reactivity of hydrocarbon compounds. The aromatic ring consists of carbon and optionally one or more heteroatoms, such as nitrogen or oxygen. However, it is preferable that each anion (ii) in the ionic solution does not contain nitrogen, sulfur, or both. Such ionic solutions are more advantageous in the present invention and have been found not to contribute to the formation of nitrogen and / or sulfur oxides (one or more) in environments where a portion of the ionic solution is consumed by combustion, such as in engine lubrication environments. Each anion (ii) in the ionic solution has a carboxylate group in its aromatic ring, and further has a functional group containing a heteroatom directly bonded to the aromatic ring, and this system has an anionic charge. Preferably, the heteroatom (one or more) in both of these functional groups consists of oxygen atoms. More preferably, these functional groups are located on adjacent ring carbon atoms in an "ortho" configuration on the aromatic ring.

[0026] In this regard, it is very preferable that each anion (ii) is a disubstituted benzene ring having a carboxylate group and a second heteroatom-containing functional group containing only oxygen as a heteroatom, and that these two groups are positioned in an "ortho" configuration relative to each other on the aromatic ring. The second functional group is a hydroxyl group, and it is preferable that this generates a hydroxybenzoate anion (ii). Most preferably, one or more anions (ii) in the ionic solution are one or more salicylate anions, i.e., anions formed from the deprotonation of salicylic acid. Each anion (ii) in the ionic solution has one or more hydrocarbyl substituents on its aromatic ring. These substituents add organic affinity to the ionic solution, making it more easily miscible with hydrocarbon bulk liquids. The hydrocarbyl substituents (one or more) of the anion are as defined above. These substituents (one or more) are preferably alkyl substituents. Suitable alkyl groups include linear or branched alkyl groups having 6 or more carbon atoms, preferably 6 to 28, and more preferably 6 to 14. Particularly suitable alkyl substituents include hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl groups, and in particular, n-alkyl groups.

[0027] The aromatic ring of anion(ii) may have one or more alkyl substituents. The resulting ionic solution may consist of a mixture of multiple anion(ii) with different numbers and / or positions of alkyl substituents. The alkyl substituents are preferably selected from the alkyl substituents specified above. Preferably, at least one of the alkyl substituents has at least 10 carbon atoms and is selected from the examples above. More preferably, the aromatic ring of each anion(ii) in the ionic solution has one or more linear or branched alkyl substituents with more than 10 carbon atoms. In the anion, it is particularly preferable that one or more, preferably all, anions (ii) are hydrocarbyl-substituted hydroxybenzoates having the following structure: [ka] In the formula, R is a linear or branched hydrocarbyl group, more preferably an alkyl group as defined above, such as a linear or branched alkyl group. There may be multiple R groups bonded to the benzene ring. The carboxylate group and the hydroxyl group are conjugated to the aromatic ring, and this system has a negative (anionic) charge. The carboxylate group can be located in the ortho, meta, or para position relative to the hydroxyl group; the ortho position is preferred. The R group can be located in the ortho, meta, or para position relative to the hydroxyl group.

[0028] In this embodiment of the anion, one or more (preferably all) anions (ii) of the ionic solution are most preferably one or more alkyl-substituted salicylate anions. Here, each alkyl substituent (one or more) of each anion is independently selected from alkyl groups having 12 to 24 carbon atoms; more preferably from dodecyl, tetradecyl, hexadecyl, and octadecyl groups.

[0029] Such hydroxybenzoate anions and salicylate anions are usually prepared by the Kolbe-Schmitt method via carboxylation of phenoxide, in which case they are generally obtained in a mixture with uncarboxylated phenol (usually in a diluent).

[0030] In particular, in ionic solutions, each cation (i) does not contain nitrogen and consists of a tetrahydrocarbyl substituted central atom or ring system having a cationic charge, and each anion (ii) has two substituted functional groups containing heteroatoms, wherein the two substituted functional groups are preferably a carboxylate group as described herein and a functional group further containing heteroatoms. It is more preferable that the heteroatoms (one or more) in both of these functional groups consist of oxygen atoms. It is most preferable that these functional groups are located on ring carbon atoms adjacent to each other in an "ortho" configuration on the aromatic ring. The preferred embodiments described herein for each of such cations (i) and anions (ii) are particularly useful when combined.

[0031] In all preferred ionic solutions, particularly in the ionic solutions of the preceding three sections, each cation (i) is most preferably an alkyl-substituted phosphonium cation, and ideally a tetraalkyl-substituted phosphonium cation as described herein. The trihexyltetradecylphosphonium cation (P66614 cation) is most preferred. Each anion is most preferably an alkyl-substituted salicylate anion, where the alkyl substituent(s) of each anion are independently selected from alkyl groups having 12 to 24 carbon atoms; more preferably from dodecyl, tetradecyl, hexadecyl, and octadecyl groups. The ionic solutions of all embodiments of the present invention may be prepared by known synthetic routes selected by those skilled in the art according to conventional synthetic criteria relating to suitability for desired cation-anion combinations.

[0032] Therefore, cation (i) can be formed from a cation-halide composite of a desired cation (ii), for example, a preferred phosphonium cation, which is then subjected to anion exchange with a desired anion precursor in a suitable solvent. An anion exchange resin may be used again to facilitate the exchange. The solvent is then removed and the ionic solution is recovered. Examples of methods for synthesizing ionic solutions are described in U.S. Patent No. 2008 / 0251759 and in the research examples described later in this specification. Individual cations and anions, or their precursors, are also available as commodities in the chemical industry. Without being bound by any particular theory, the applicant believes that the specific advantages of the present invention's ionic solution in inactivating the decomposition of nitrogen dioxide arise from the composition of the ionic solution and the elucidated mechanism of action, and that when both anions and cations are combined, they play a beneficial role. Firstly, the functionalized aromatic anion (ii) in the ionic liquid ion pair particularly interacts with nitrogen dioxide molecules, making it highly capable of effectively removing nitrogen dioxide molecules from the reaction cycle in the hydrocarbon liquid. As a result, the initial deprotonation of hydrocarbon components in the bulk liquid is inhibited, as is the nitrification reaction sequence and the formation of nitrate esters, thereby slowing the decomposition of the bulk liquid over time.

[0033] Next, it is hypothesized that nitric acid, formed in situ from the oxidation of some of the bound nitrogen dioxide, is captured by the corresponding cation in the ionic solution. This nitric acid then loses its acidic proton to a negatively charged anion-nitrogen dioxide complex, forming an ion pair containing the ionic solution cation and the nitrate anion, and further forming a complex between the protonated anion and the remaining bound nitrogen dioxide. This sequence also effectively removes nitric acid from the reaction cycle in the hydrocarbon solution. As a result, the accumulation of acid in the hydrocarbon solution over time is also slowed, and the ionic solution helps to contain acid-mediated oxidation and acid attack in the hydrocarbon solution and the machinery beneath it. In this way, the cations and anions in the ionic solution interact in combination to inhibit the decomposition of the hydrocarbon solution as a result of nitrogen dioxide contamination, thereby extending its operational life. Furthermore, the applicant believes that the reduction of friction and / or wear by the ionic solution of the present invention is due to its specific composition, which advantageously protects the contact surfaces of the mechanism of interest.

[0034] Additive composition according to a second aspect of the present invention A second aspect of the present invention is an additive composition for a hydrocarbon liquid comprising the ionic liquid, carrier liquid, and optionally additional additives according to the first aspect. The additive composition is preferably in the form of a concentrate that allows the ionic liquid to be added to the hydrocarbon liquid without the need to introduce a large amount of excess carrier liquid. To facilitate mixing or blending, it is desirable to prepare one or more additive concentrates according to the second embodiment, which include an ionic solution in a carrier solution (a diluent or solvent that is mutually compatible with both ionic and hydrocarbon solutions), thereby allowing other additives to be added to the concentrate simultaneously or sequentially (such concentrates may be referred to as additive packages). In the second embodiment, when an additive concentrate is used, its content may be 5 to 25% by mass of the ionic solution, preferably 5 to 22% by mass, and typically 10 to 20% by mass, with the remainder of the concentrate being a solvent or diluent. As a convenient method for simultaneously incorporating multiple additives into a hydrocarbon liquid, the additive composition (and preferably the additive concentrate composition) may contain additional additives. Such additional additives can have diverse properties and applications depending on the needs of the operating fluid in question. When using the additive concentrate of the second embodiment, its content may be 5 to 25% by mass of the ionic solution, preferably 5 to 22% by mass, and typically 10 to 20% by mass, with the remainder of the concentrate being a solvent or diluent. In particular, when the hydrocarbon liquid is a lubricating oil or power transmission oil, especially an engine lubricating oil, various additional additives may be incorporated to enhance other properties of the lubricant. These additional additives may include one or more phosphorus-containing compounds; dispersants; metal cleaning agents; anti-wear agents; friction modifiers, viscosity modifiers; antioxidants; and other co-additives, although these additives differ from the essential ionic liquids described herein. These additives are described in more detail below.

[0035] Suitable phosphorus-containing compounds include metal salts of dihydrocarbyl dithiophosphate, which are frequently used as wear-resistant agents. The metal is preferably zinc, but may be an alkali metal or alkaline earth metal, or aluminum, lead, tin, molybdenum, manganese, nickel, or copper. Zinc salts are most commonly used in lubricating oils in amounts of 0.1 to 10% by mass, preferably 0.2 to 2% by mass, relative to the total mass of the lubricating oil composition. Zinc salts may be prepared according to known techniques by first reacting P2S5 with one or more alcohols or phenols to form dihydrocarbyl dithiophosphate (DDPA), and then neutralizing the formed DDPA with a zinc compound. For example, dithiophosphate may be produced by reacting a mixture of primary and secondary alcohols. Alternatively, multiple dithiophosphates can be prepared if one hydrocarbyl group is entirely secondary in nature and the other hydrocarbyl group is entirely primary in nature. Any basic or neutral zinc compound can be used to produce zinc salts, but oxides, hydroxides, and carbonates are the most commonly used. Commercial additives often contain excess zinc because they use an excess amount of basic zinc compound in the neutralization reaction.

[0036] A preferred zinc dihydrocarbyl dithiophosphate is an oil-soluble salt of dihydrocarbyl dithiophosphate, which may also be represented by the following formula: [ka] In the formula, R and R' may be the same or different hydrocarbyl radicals having 1 to 18 carbon atoms, preferably 2 to 12, and examples include alkyl, alkenyl, aryl, arylalkyl, alkaryl, and alicyclic radicals. In this context, the R and R' groups are particularly preferably alkyl groups having 2 to 8 carbon atoms. Therefore, these radicals may be, for example, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, amyl, n-hexyl, i-hexyl, n-octyl, decyl, dodecyl, octadecyl, 2-ethylhexyl, phenyl, butylphenyl, cyclohexyl, methylcyclopentyl, propenyl, and butenyl. To obtain oil solubility, the total number of carbon atoms in dithiophosphate (i.e., R and R') is generally 5 or more. Therefore, zinc dihydrocarbyl dithiophosphate (ZDDP) can contain zinc dialkyldithiophosphate. The phosphorus content in the additive concentrate of the present invention for lubricants may be about 0.08% by mass (800 ppm) or less. Preferably, in the implementation of the present invention, ZDDP is used in an amount close to or equal to the maximum permissible amount, preferably in an amount such that the phosphorus content is within 100 ppm, which is the maximum permissible amount of phosphorus. Therefore, it is preferable that the resulting lubricating oil composition contains ZDDP or other zinc-phosphorus compounds in an amount such that the phosphorus content is 0.01 to 0.08% by mass, for example 0.04 to 0.08% by mass, preferably 0.05 to 0.08% by mass, relative to the total mass of the lubricating oil composition.

[0037] Dispersants are additives whose primary function is to retain oil-insoluble contaminants in a suspension, thereby passivating the contaminants and reducing their deposition on surfaces. For example, dispersants maintain oil-insoluble substances in a suspension that result from oxidation during use, preventing solids from agglomerating, settling, or depositing on machine parts. The dispersant in this invention is preferably "ashless" and is a non-metallic organic material that does not form ash during combustion, in contrast to materials that form ash due to the presence of metals. The dispersant contains a long hydrocarbon chain with a polar tip, and its polarity preferably derives from the presence of oxygen, phosphorus, or nitrogen atoms. The hydrocarbon is a lipophilic group that imparts oil solubility and has, for example, 40 to 500 carbon atoms, or for example, 60 to 250 carbon atoms. Therefore, the ashless dispersant may also contain an oil-soluble polymer backbone. The number-average molecular weight (Mn) of the hydrocarbon portion of the dispersant may be 800 to 5000 g / mol, for example, 900 to 3000 g / mol. Preferred types of olefin polymers include polybutene, specifically polyisobutene (PIB), or poly-n-butene, which may be prepared, for example, by polymerization in a C4 purified flow.

[0038] Examples of dispersants include derivatives of long-chain hydrocarbon-substituted carboxylic acids, such as high molecular weight derivatives of hydrocarbyl-substituted succinic acid. Typically, hydrocarbon polymer materials such as polyisobutylene are reacted with acylation groups (e.g., maleic acid or anhydride) to form hydrocarbon-substituted succinic acid (succinate). Notable groups in dispersants consist of hydrocarbon-substituted succinimides formed by reacting the above-mentioned acid (or derivative) with a nitrogen-containing compound, preferably a polyalkylene polyamine, such as polyethylene polyamine. Reaction products of polyalkylene polyamines and alkenyl succinic anhydrides, as described in U.S. Patents 3,202,678, 3,154,560, 3,172,892, 3,024,195, 3,024,237, 3,219,666, and 3,216,936, are particularly preferred and may be post-treated to improve their properties, for example, by borolysis (described in U.S. Patents 3,087,936 and 3,254,025), fluorination, or oxylation. For example, borolysis may be carried out by treating an acyl nitrogen-containing dispersant with a boron compound selected from boron oxide, boron halides, boric acid, and esters of boric acid. Preferably, the dispersant, if present, is a polyisobutene-derived succinimide dispersant with moderate functionality and a number-average molecular weight in the range of 800 to 5000 g / mol, for example, 1000 to 3000 g / mol, preferably 1500 to 2500 g / mol. The succinimide is preferably derived from highly reactive polyisobutene. Another example of a dispersant type that may be used is a linked aromatic compound, as described in European Patent Application Publication No. 090 642. Combining succinimide borooxide with non-succinimide borooxide is useful in this specification. It is useful herein to combine one or more (e.g., two or more) high-Mn succinimides (1500 g / mol or more, e.g., 2000 g / mol or more Mn) with one or more (e.g., two or more) low-Mn succinimides (less than 1500 g / mol, e.g., less than 1200 g / mol Mn), and such combinations may optionally contain one, two, three, or more types of borooxide succinimides. Detergents are additives that suppress the formation of precipitates, such as those in high-temperature varnishes and lacquers; they typically have acid-neutralizing properties and can maintain a finely ground solid state in suspension. Most detergents are based on metal "soaps," that is, metal salts of acidic organic compounds.

[0039] Detergents generally contain a polar tip with a long hydrophobic tail, the polar tip containing a metal salt of an acidic organic compound. When the salt is usually described as an ordinary salt or a neutral salt, it may contain an almost stoichiometric amount of metal, and typically its total base number or "TBN" is 0 to 150 mg KOH / g, for example 10 to 80 mg KOH / g, in 100% active mass (measured according to ASTM D2896). It is possible to include a large amount of metal base by reacting an excess amount of metal compound, such as an oxide or hydroxide, with an acidic gas such as carbon dioxide. The resulting overbasic detergent contains a neutralizing detergent as an outer layer of metal base (e.g., carbonate) micelles. The total base number (TBN) of such an overbasic detergent may be greater than 150 mgKOH / g in 100% active mass, for example 200 mgKOH / g or more, for example 250 mgKOH / g or more, typically 200-800 mgKOH / g, 225-700 mgKOH / g, for example 250-650 mgKOH / g, or 300-600 mgKOH / g, for example 150-650 mgKOH / g, preferably 200-500 mgKOH / g or more. Preferably, the cleaning agents that can be used include oil-soluble neutral and overbasic sulfonates, phenates, phenate sulfides, thiophosphates, salicylates, and naphthenates, as well as other oil-soluble carboxylates of metals, particularly alkali metals or alkaline earth metals, such as Na, K, Li, Ca, and Mg. The most commonly used metals are Ca and Mg, both of which may be included in cleaning agents used in lubricating compositions as mixtures of Ca and / or Mg with Na. The cleaning agents may be used in various combinations.

[0040] Preferably, the cleaning additive(s) useful in the present invention include calcium and / or magnesium metal salts. The cleaning agent may be a calcium and / or magnesium carboxylate (e.g., salicylate), sulfonate, or phenate cleaning agent. More preferably, the cleaning additive is selected from magnesium salicylate, calcium salicylate, magnesium sulfonate, calcium sulfonate, magnesium phenate, calcium phenate, and hybrid cleaning agents and / or combinations thereof, comprising two, three, four, or more of these cleaning agents. In magnesium cleaning agents, the lubricating composition contains 200 to 4000 ppm, preferably 200 to 2000 ppm, 300 to 1500 ppm, or 450 to 1200 ppm of magnesium atoms (ASTM D5185). Calcium detergents are typically present in an amount sufficient to provide the lubricating oil composition with at least 500 ppm, preferably at least 750 ppm, and more preferably at least 900 ppm of calcium atoms (ASTM D5185). If present, any calcium detergent is preferably present in an amount sufficient to provide the lubricating oil composition with 4000 ppm or less, preferably 3000 ppm or less, and more preferably 2000 ppm or less of calcium atoms (ASTM D5185). If present, any calcium detergent is preferably present in an amount sufficient to provide the lubricating oil composition with 500 to 4000 ppm, preferably 750 to 3000 ppm, and more preferably 900 to 2000 ppm of calcium atoms (ASTM D5185).

[0041] The detergent composition may include (or be composed of) a combination of one or more magnesium sulfonate detergents and one or more calcium salicylate detergents. In a combination of one or more magnesium sulfonate detergents and one or more calcium salicylate detergents, the lubricant composition contains: 1) 200 to 4000 ppm, preferably 200 to 2000 ppm, 300 to 1500 ppm, or 450 to 1200 ppm of magnesium atoms (ASTM D5185), and 2) at least 500 ppm, preferably at least 750 ppm, more preferably at least 900 ppm of calcium atoms, for example, 500 to 4000 ppm, preferably 750 to 3000 ppm, more preferably 900 to 2000 ppm of calcium atoms (ASTM D5185). Additional additives may be incorporated into the additive concentrate of the present invention to enable the meeting of specific performance requirements. Examples of such additives that may be included in the lubricating oil composition of the present invention include friction modifiers, viscosity modifiers, metal rust inhibitors, viscosity index improvers, corrosion inhibitors, antioxidants, defoamers, anti-wear agents, and pour point depressants.

[0042] The lubricating oil composition may also contain friction modifiers (and, in the case of engine lubricants, fuel-saving agents) that are compatible with the other components of the hydrocarbon fluid. Examples of such materials include glyceryl monoesters of higher fatty acids, e.g., glyceryl monooleates; esters of long-chain polycarboxylic acids containing diols, e.g., butanediol esters of dimerized unsaturated fatty acids; and alkoxylated alkyl-substituted monoamines, diamines, and alkyl etheramines, e.g., ethoxylated tallowamines and ethoxylated tallow etheramines. Other known friction modifiers include oil-soluble organic molybdenum compounds. Such organic molybdenum friction modifiers impart antioxidant properties and antiwear credits to lubricating oil compositions. Examples of such oil-soluble organic molybdenum compounds include dithiocarbamites, dithiophosphates, dithiophosphinates, xanthogenicates, thiooxantogenicates, sulfides, and mixtures thereof. Molybdenum dithiocarbamites, dialkyldithiophosphates, alkylxanthogenicates, and alkylthiooxantogenicates are particularly preferred. Furthermore, the molybdenum compounds may also be acidic molybdenum compounds. These compounds react with basic nitrogen compounds as measured by ASTM test D-664 or D-2896 titration procedures and are typically hexavalent. Examples of molybdenum compounds include molybdic acid, ammonium molybdate, sodium molybdate, potassium molybdate, and other alkali metal molybdates, as well as other molybdenum salts, such as sodium hydrogen molybdate, MoOCl4, MoO2Br2, Mo2O3Cl6, molybdenum trioxide, or similar acidic molybdenum compounds. Among the molybdenum compounds useful in the compositions of the present invention are organic molybdenum compounds represented by the following formula: Mo(R”OCS2)4, and Mo(R”SCS2)4 In the formula, R'' is an organic group selected from the group consisting of alkyl, aryl, aralkyl, and alkoxyalkyl groups, generally having 1 to 30 carbon atoms, preferably 2 to 12 carbon atoms, with alkyl groups having 2 to 12 carbon atoms being the most preferred. Dialkyldithiocarbamic acid of molybdenum is particularly preferred.

[0043] Another group of organic molybdenum compounds useful as additional additives in the present invention includes trinuclear molybdenum compounds, particularly those of the formula Mo3S k A n D z The compound and mixtures thereof are included. In the formula, A is an independently selected ligand having an organic group with a sufficient number of carbon atoms to make the compound soluble or dispersible in oil, n is 1 to 4, k is in the range of 4 to 7, D is selected from the group of neutral electron-donating compounds such as water, amines, alcohols, phosphines, and ethers, and z is in the range of 0 to 5, including non-stoichiometric values. It is desirable that all ligand organic groups have at least 21 carbon atoms, for example, at least 25, at least 30, or at least 35 carbon atoms. When the hydrocarbon liquid is a lubricating oil, it is preferable that the hydrocarbon liquid contains at least 10 ppm, at least 30 ppm, at least 40 ppm, and more preferably at least 50 ppm of molybdenum. Preferably, the molybdenum content of such a lubricating oil composition is 1000 ppm or less, 750 ppm or less, or 500 ppm or less. In the present invention, the molybdenum content of a useful lubricating oil composition is preferably 10 to 1000 ppm, for example, 30 to 750 ppm, or 40 to 500 ppm (measured as molybdenum atoms).

[0044] The viscosity index of hydrocarbon liquids, particularly lubricating oils, may be increased or improved by incorporating specific polymer materials that function as viscosity modifiers (VM) or viscosity index improvers (VII). Generally, the number-average molecular weight (Mn) of polymer materials useful as viscosity modifiers is 5,000 to 250,000, preferably 15,000 to 200,000, and more preferably 20,000 to 150,000. These viscosity modifiers can be grafted with graft materials, such as maleic anhydride. These graft materials can be reacted with, for example, amines, amides, nitrogen-containing heterocyclic compounds, or alcohols to form multifunctional viscosity modifiers (dispersant-viscosity modifiers). Polymers prepared using diolefins will contain ethylenically unsaturated polymers, and such polymers are preferably hydrogenated. When hydrogenating polymers, hydrogenation may be carried out by any technique known in the prior art. For example, hydrogenation may be carried out to convert (saturate) both ethylenically unsaturated and aromatically unsaturated polymers using methods such as those taught in U.S. Patent No. 3,113,986 and No. 3,700,633. Alternatively, hydrogenation may be carried out selectively to convert most of the ethylenically unsaturated polymers without converting most or all of the aromatically unsaturated polymers, as taught in, for example, U.S. Patent No. 3,634,595; No. 3,670,054; No. 3,700,633 and reissue No. 27,145. Any of these methods can also be used to hydrogenate polymers that contain only ethylenically unsaturated polymers and no aromatically unsaturated polymers.

[0045] PPDs lower the minimum temperature at which bulk liquids flow and may be included in lubricating oils in particular. PPDs can be grafted with graft materials, such as maleic anhydride. These graft materials can be reacted with, for example, amines, amides, nitrogen-containing heterocyclic compounds, or alcohols to form multifunctional additives. In the present invention, it may be advantageous to include co-additives that maintain the viscosity stability of the blend. Thus, while polar group-containing additives suitably achieve low viscosity in the pre-blending stage, it has been observed that some compositions experience an increase in viscosity during long-term storage. Effective additives for controlling this viscosity increase include long-chain hydrocarbons functionalized by reaction with mono- or dicarboxylic acids or anhydrides used in the preparation of ashless dispersants, as disclosed herein.

[0046] Hydrocarbon liquid composition according to a third aspect of the present invention In a third aspect, the present invention provides a hydrocarbon liquid containing an ionic liquid of the first aspect or an additive concentrate of the second aspect, wherein the amount of the ionic liquid is a maximum of 5.0% by mass of the hydrocarbon liquid. The hydrocarbon liquid formulated in this embodiment of the present invention is suitable for operation at bulk liquid temperatures of 60 to 180°C and is free from aging components and nitrogen dioxide contamination before operation. Such operating fluids are used in a variety of applications, including industrial and automotive oils, and power transmission fluids such as engine lubricants. The hydrocarbon liquid is preferably a lubricant for machinery. More preferably, the hydrocarbon liquid is a crankcase lubricant for an internal combustion engine, which is contaminated with nitrogen dioxide from exhaust gases during operation. These exhaust gases are incorporated into the lubricant by the gas blow-through effect into the crankcase and come into direct contact with the cylinder walls of the engine. Most preferably, this crankcase lubricant is periodically or continuously exposed to a bulk liquid temperature of 110-160°C inside the crankcase. For this method to be advantageous, it is important that, prior to operation, the hydrocarbon liquid is initially free from nitrogen dioxide contamination, does not initially contain aged liquid components resulting from oxidative or other chemical decomposition during operation, and does not contain large amounts of reactive chemical species that could lead to alternative or complementary decomposition pathways to nitrification initiated by nitrogen dioxide. Therefore, the hydrocarbon liquid should be freshly prepared and not used in previous operations; and it should not be pre-mixed with or diluted with any previously used or nitrogen dioxide-contaminated aged liquid before being placed in the operating environment. Also, prior to operation and the onset of the resulting high temperatures and nitrogen dioxide pollution, it is important to add an ionic liquid to maximize its nitrification inhibition effect and impede the increase in nitrogen dioxide concentration in the bulk liquid. The hydrocarbon liquid used as the bulk operating liquid may be obtained from petroleum or synthetic sources or from the processing of renewable materials such as biomaterials.

[0047] When the hydrocarbon liquid is petroleum, particularly lubricating oil, the viscosity of such an oil agent ranges from light fraction mineral oil to heavy lubricating oils such as gasoline engine oil, mineral lubricating oil, and high-load diesel oil. Generally, the kinematic viscosity of the oil agent, measured at 100 °C (ASTM D445-19a), is about 2 mm 2 / s (centistokes) to about 40 mm 2 / s, particularly about 3 mm 2 / s to about 20 mm 2 / s, most preferably about 9 mm 2 / s to about 17 mm 2 / s. Suitable oil agents, particularly lubricating oils, include natural oils such as animal and vegetable oils (e.g., castor oil, lard oil); liquid petroleum and hydrorefined, solvent-treated, or acid-treated mineral oils of paraffinic, naphthenic, and paraffin-naphthene mixed types. Lubricating viscous oils derived from coal or shale also function as useful bulk oil agents. Synthetic oils, particularly synthetic lubricants, include hydrocarbon oils and halo-substituted hydrocarbon oils that retain hydrocarbon properties, such as polymerized and copolymerized olefins (e.g., ethylene-propylene copolymers, polybutylene monopolymers and copolymers, polypropylene monopolymers and copolymers, propylene-isobutylene copolymers, chlorinated polybutylene, poly(1-hexene), poly(1-octene), poly-n-decene (e.g., decene monopolymers, or copolymers of decene with one or more C8-C20 alkenes other than decene, such as octene, nonene, undecene, dodecene, tetradecene, etc.)); alkylbenzenes (e.g., dodecylbenzene, tetradecylbenzene, dinonylbenzene, di(2-ethylhexyl)benzene); polyphenyls (e.g., biphenyl, terphenyl, alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenyl sulfides, as well as their derivatives, analogs, and congeners. Furthermore, synthetic oils obtained from Fischer-Tropsch-synthesized hydrocarbons through a gas-to-liquid process are also useful, and these are generally called gas-to-liquid or "GTL" base oils. Esters are useful as synthetic oils with hydrocarbon properties, and examples include those formed from C5-C12 monocarboxylic acids, as well as polyols and polyol esters such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tripentaerythritol.

[0048] When the hydrocarbon liquid is a lubricating oil, the hydrocarbon liquid may contain a base stock of Group I, Group II, Group III, Group IV, or Group V, or a blend of the aforementioned base stocks. Preferably, the lubricating oil is a base stock of Group II, Group III, Group IV, or Group V, or a mixture thereof, for example, a mixture of a Group I base stock and one or more base stocks of Group II, Group III, Group IV, or Group V. The definitions of these base stocks and base oils are given in the Engine Oil Licensing and Certification System ("ELOCS"), Industry Services section, December 1996, 14th edition, Appendix 1, December 1998, published by the American Petroleum Institute (API). Preferably, the saturation content of the base stock or base stock blend is at least 65%, more preferably at least 75%, for example at least 85%. Preferably, the base stock or base stock blend is a base stock or base stock mixture of Group III or higher, or a mixture of Group II base stock and a base stock or base stock mixture of Group III or higher. Most preferably, the saturation content of the base stock or base stock blend exceeds 90%. Preferably, the sulfur content of the oil or oil blend is less than 1% by mass, preferably less than 0.6% by mass, most preferably less than 0.4% by mass, for example less than 0.3% by mass (measured as shown in API EOLCS). Group III base stocks have been found to have higher wear credit compared to Group I base stocks, and therefore, in one preferred embodiment, at least 30% by mass, preferably at least 50% by mass, and more preferably at least 80% by mass of the lubricating oil is Group III base stock.

[0049] Preferably, the volatility of the lubricating oil or lubricating oil blend is 30% by mass or less, for example, about 25% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less, and most preferably 13% by mass or less, as measured by the Noack test (ASTM D5800). Preferably, the viscosity index (VI) of the oil or oil blend is at least 85, preferably at least 100, and most preferably about 105 to 140 (ASTM D2270). In this aspect of the present invention, the ionic solution can be added to the hydrocarbon solution by physical mixing or blending techniques known in the art. Although not essential, it may be desirable to prepare one or more additive concentrates of a second aspect containing the ionic solution in a carrier solution (a diluent or solvent that is mutually compatible with both the ionic solution and the hydrocarbon solution) to facilitate mixing or blending, thereby allowing other additives to be added simultaneously to the concentrate and, consequently, to the oil to form a lubricating oil composition (such concentrates may be referred to as additive packages). The ionic solution may be added to the additive concentrate before combining the concentrate with the hydrocarbon solution, or to the combination of the additive concentrate and the hydrocarbon solution. The ionic solution may be added to the additive package before combining the package with the hydrocarbon solution, or to the combination of the additive package and the hydrocarbon solution.

[0050] When using the additive concentrate of the second embodiment, its content may be 5 to 25% by mass, preferably 5 to 22% by mass, and typically 10 to 20% by mass, relative to the mass of the ionic solution concentrate, with the remainder of the concentrate being a solvent or diluent. When using an additive package, its content may be 5 to 25% by mass, preferably 5 to 22% by mass, and typically 10 to 20% by mass, relative to the mass of the ionic solution concentrate, with the remainder of the package being other additives (e.g., dispersants, cleaning agents, etc.), solvents, or diluents. If the hydrocarbon liquid contains one or more of the additional additives described above in addition to the ionic liquid, each additional additive is typically blended into the bulk liquid in an amount that allows the additive to perform the desired function. Typical effective amounts of such additional additives when used in hydrocarbon liquids as crankcase lubricants are listed in the table below. All values ​​listed (excluding detergents, as detergents are used in the form of colloidal dispersants in oil) are expressed as active ingredients (AI) as mass percentages. These amounts of additional additives are used in combination with the amount of ionic liquid described herein. [Table 1]

[0051] Use of the fourth aspect of the present invention In a fourth aspect, the present invention provides the use of the ionic solution of the first aspect or the additive concentrate of the second aspect as an additive to a hydrocarbon solution for chemically inactivating nitrogen dioxide incorporated into the hydrocarbon solution. In the use of the fourth aspect, the ionic solution consequently inhibits the formation of hydrocarbon nitrate esters and extends the operational life of the hydrocarbon solution. In this application, the effectiveness of the ionic solution in inhibiting the nitrification reaction initiated by nitrogen dioxide on hydrocarbon compounds at high temperatures delays the initiation of bulk liquid decomposition via this chemical pathway, thereby extending its operational life. The ionic solution initially acts by inhibiting proton extraction by nitrogen dioxide, which initiates nitrification of the bulk liquid, delaying the initial formation of free radicals that lead to other chemical reactions further down the pathway, thus delaying the initiation of significant decomposition. The ionic solution further acts in the latter half of the pathway by inhibiting the formation of hydrocarbon nitrate esters from the reaction between nitrogen dioxide and subsequent RO radicals, reducing the accumulation of these reactive compounds in the bulk liquid. As a result, the bulk liquid is exposed to low concentrations of released RO radicals at high temperatures, especially under continuous or periodic increases in operating temperature above 110°C, where the dissociation rate of these nitrate esters increases significantly, enhancing the severe decomposition of the bulk liquid.

[0052] The amount of ionic solution effective in inhibiting nitrification in this application can be determined by routine testing under conditions that reproduce or simulate nitrogen dioxide contamination at high operating temperatures experienced in the target system. In this preferred embodiment of use, the chemical decomposition inhibited by the ionic solution is due to the decomposition of hydrocarbon nitrate esters formed during operation by nitrification of the hydrocarbon solution with nitrogen dioxide at bulk liquid temperatures of 60 to 180°C, and the ionic solution is used to inhibit the formation of hydrocarbon nitrate esters during operation. In this way, the accumulation of reactive hydrocarbon nitrate esters in the storage area at high operating temperatures is directly inhibited, and decomposition is more effectively limited. In a more preferred embodiment of this use, the chemical decomposition inhibited by the ionic solution is caused by the decomposition of hydrocarbon nitrate esters due to periodic or continuous exposure of the hydrocarbon solution to a bulk solution temperature of 110-160°C during operation, and the ionic solution is used to inhibit the formation of hydrocarbon nitrate esters during operation. In this way, the more rapid and serious decomposition that occurs during operation at high temperatures is directly inhibited.

[0053] In these embodiments of the present invention, the level of nitrate ester formation in the bulk liquid can be determined spectroscopically by observing the time-dependent increase in the infrared peak height associated with nitrate esters in the bulk liquid under preferred test conditions. This spectroscopic approach allows for the determination of the amount of ionic solution required to inhibit nitrate ester formation in the bulk liquid. Inhibition of hydrocarbon nitrate ester formation during operation is determined by observing a decrease in the nitrate ester peak height in the bulk liquid in the presence of the ionic solution. This peak height is measured by infrared spectroscopy under similar operating and nitrogen dioxide contamination conditions, in accordance with German Industrial Standard (DIN) 51 453 or ASTM Standard (ASTM) D8048-20 (if there is a discrepancy between DIN 51 453 and ASTM D8048-20, DIN 51 453 shall prevail). According to the DIN method, 1630 cm⁻¹ -1 The height of the single infrared absorption frequency is 1615 cm². -1 and 1645cm -1The peak height is measured higher than the linear baseline defined by the absorbance. A higher peak height indicates a higher concentration of nitrate esters in the bulk liquid. By measuring a series of samples taken over time, it is possible to track the change in peak height associated with changes in nitrate ester levels in the working fluid over time. According to the ASTM D8048-20 standard test method, the peak heights for oxidation and nitrification are measured by first subtracting the infrared spectrum of a new oil. The baseline is 1950 cm⁻¹. -1 ~1850cm -1 Defined by absorbance, the highest peak is 1740 cm⁻¹ in oxidation. -1 ~1700cm -1 In the range of nitrification, it is 1640 cm -1 ~1620cm -1 That is the case.

[0054] The amount of reduction or limitation of nitrate ester formation in the lubricating oil composition is determined by observing that the nitrate ester peak height in the presence of the lubricating oil composition containing the ionic solution is lower (at least 10%, e.g., at least 20%, e.g., at least 30%, e.g., at least 40%, e.g., at least 50%, e.g., 100% lower) compared to the nitrate ester peak of the same lubricating oil composition where the ionic solution is replaced with an ionic solution having the same cation but the same proportion of hexanoate as anion. This peak height is measured by infrared spectroscopy according to DIN51 453 or ASTM D8048-20 under similar operating and nitrogen dioxide contamination conditions, provided that if there is a discrepancy between DIN51 453 and ASTM D8048-20, DIN51 453 shall be followed. However, under normal circumstances, the amount of ionic solution added to inhibit nitrification of the hydrocarbon liquid during operation at bulk liquid temperatures of 60°C or higher, for example 110°C or higher, for example 60-180°C (e.g., 60-180°C, for example 60-160°C, for example 110-160°C, for example 130-160°C) in the presence of nitrogen dioxide contamination is 0.1 to 5.0% by mass per unit mass of the hydrocarbon liquid; preferably, in the range of 0.5 to 4.0% by mass per unit mass of the hydrocarbon liquid. More preferably, the ionic solution is added in an amount of 1.0 to 3.5% by mass per unit mass of the hydrocarbon liquid; most preferably, in the range of 1.0 to 3.0% by mass per unit mass of the hydrocarbon liquid.

[0055] The hydrocarbon liquid formulated by the method of the present invention is suitable for operation at bulk liquid temperatures of 60°C or higher, for example 110°C or higher, for example 60-180°C (e.g., 60-180°C, for example 60-160°C, for example 110-160°C, for example 130-160°C), and is a liquid that is free from (or nearly free from, e.g., less than 5 ppm of aged components and less than 10 ppm of nitrogen dioxide contamination) of aged components and nitrogen dioxide contamination before operation. Such operating fluids are used in a variety of applications, such as industrial and automotive oils, and power transmission fluids such as engine lubricants. In this application, the hydrocarbon liquid is preferably a lubricating oil for machinery. More preferably, the hydrocarbon liquid is a crankcase lubricating oil for an internal combustion engine, which is contaminated with nitrogen dioxide from exhaust gases during operation. These exhaust gases are incorporated into the lubricant by the gas blow-through effect into the crankcase and come into direct contact with the cylinder walls of the engine. Most preferably, this crankcase lubricating oil is periodically or continuously exposed to the bulk liquid temperature of 110-160°C inside the crankcase. For this use to be beneficial, it is important that, prior to operation, the hydrocarbon liquid is initially free from nitrogen dioxide contamination, does not initially contain aged liquid components resulting from oxidative or other chemical decomposition during operation, and does not contain large amounts of reactive chemical species that could lead to alternative or complementary decomposition pathways to nitrification initiated by nitrogen dioxide. Therefore, preferably, the hydrocarbon liquid should be freshly prepared and not used in previous operations; and it should not be pre-mixed with or diluted with any previously used or nitrogen dioxide-contaminated aged liquid before being placed in the operating environment.

[0056] Alternatively, prior to operation, the hydrocarbon liquid may initially contain virtually no nitrogen dioxide contamination (less than 10 ppm, e.g., less than 5 ppm, e.g., 0 ppm), and also contain virtually no aged liquid components resulting from oxidative or other chemical breakdown during operation (less than 10 ppm, e.g., less than 5 ppm, e.g., 0 ppm) (or, for example, virtually no aged components (less than 0.0001% by mass) and virtually no nitrogen dioxide contamination (less than 10 ppm). Furthermore, prior to the start of operation and the resulting high temperatures and nitrogen dioxide contamination, it is important to add an ionic solution to maximize its nitrification inhibitory effect and prevent an increase in the nitrogen dioxide concentration in the bulk liquid. In this embodiment of use, the ionic solution can be added to the hydrocarbon solution by physical mixing or blending techniques known in the art. Although not essential, it may be desirable to prepare one or more additive concentrates of a second embodiment containing the ionic solution in a carrier solution (a diluent or solvent that is mutually compatible with both the ionic solution and the hydrocarbon solution) to facilitate mixing or blending, thereby allowing other additives to be added simultaneously to the concentrate and, consequently, to the oil to form a lubricating oil composition (such concentrates may be referred to as additive packages). When additive concentrates are used, their content may be 5 to 25% by mass of the ionic solution, preferably 5 to 22% by mass, and typically 10 to 20% by mass, with the remainder of the concentrate being a solvent or diluent. The advantageous properties of this method for chemically inactivating nitrogen dioxide incorporated into hydrocarbon liquids and limiting chemical decomposition by nitrification will be demonstrated below in the research examples of the present invention.

[0057] Use of the Fifth Aspect of the Invention In a fifth aspect, the present invention provides the use of the ionic liquid of the first aspect or the additive concentrate of the second aspect as an additive for hydrocarbon liquid lubricants to reduce the coefficient of friction of the lubricant, improve resistance to mechanical wear, or both. In the fifth embodiment of the invention, the ionic solution is preferably used to chemically inactivate nitrogen dioxide incorporated into the hydrocarbon lubricant, and more preferably to inhibit the increase in the total acid number of the hydrocarbon lubricant during operation as measured according to ASTM D664, as described in the fourth embodiment of the invention. Suitable and preferred ionic and hydrocarbon solutions in the fifth embodiment of the present invention are those already described herein. The amount of ionic solution effective in reducing the coefficient of friction, improving resistance to mechanical wear, or both can be determined by comparing the effect of ionic solution addition on the baseline performance of the hydrocarbon liquid lubricant in question using industry-recognized friction and wear tests.

[0058] However, under normal circumstances, the amount of ionic solution used for friction, wear, or both of a hydrocarbon-based liquid lubricant during operation is in the range of 0.1 to 5.0% by mass of the hydrocarbon solution; preferably 0.5 to 4.0% by mass of the hydrocarbon solution. More preferably, the ionic solution is used in an amount in the range of 1.0 to 3.5% by mass of the hydrocarbon solution; most preferably, in an amount in the range of 1.0 to 3.0% by mass of the hydrocarbon solution. The amount of ionic solution effective in inhibiting nitrification in a preferred embodiment of the present invention can be determined by routine testing under conditions that reproduce or simulate nitrogen dioxide contamination at high operating temperatures experienced in the system in question. In this preferred embodiment of use, the chemical decomposition inhibited by the ionic solution is due to the decomposition of hydrocarbon nitrate esters formed during operation by nitrification of the hydrocarbon solution with nitrogen dioxide at bulk liquid temperatures of 60 to 180°C, and the ionic solution inhibits the formation of hydrocarbon nitrate esters during this operation. In this way, the accumulation of reactive hydrocarbon nitrate esters in the storage area at high operating temperatures is directly inhibited, and decomposition is more effectively limited. In a more preferred embodiment of this use, the chemical decomposition inhibited by the ionic solution is caused by the decomposition of hydrocarbon nitrate esters by periodically or continuously exposing the hydrocarbon solution to a bulk solution temperature of 110-160°C during operation, and the ionic solution inhibits the formation of hydrocarbon nitrate esters during operation. Thus, it directly inhibits the more rapid and serious decomposition that occurs during operation at high temperatures.

[0059] In these embodiments of the present invention, the level of nitrate ester formation in the bulk liquid can be determined spectroscopically by observing the time-dependent increase in the infrared peak height associated with nitrate esters in the bulk liquid under preferred test conditions. This spectroscopic approach allows observation of the effect of ionic solutions on inhibiting nitrate ester formation in the bulk liquid. Inhibition of hydrocarbon nitrate ester formation during operation is determined by observing a decrease in the nitrate ester peak height in the bulk liquid in the presence of an ionic solution. This peak height is measured by infrared spectroscopy according to DIN 51 453 under similar operating and nitrogen dioxide contamination conditions. According to this DIN method, 1630 cm⁻¹ -1 The height of the single infrared absorption frequency is 1615 cm². -1 and 1645cm -1 The measurement is higher than the linear baseline defined by the absorbance. A higher peak height indicates a higher concentration of nitrate esters in the bulk liquid. By measuring a series of samples taken over time, it becomes possible to track the change in peak height in response to changes in nitrate ester levels in the operating solution over time. However, under normal conditions, the amount of ionic solution used to inhibit nitrification of the hydrocarbon liquid during operation at bulk liquid temperatures of 60 to 180°C in the presence of nitrogen dioxide contamination is 0.1 to 5.0% by mass per unit mass of the hydrocarbon liquid; preferably, in the range of 0.5 to 4.0% by mass per unit mass of the hydrocarbon liquid. More preferably, the ionic solution is used in an amount in the range of 1.0 to 3.5% by mass per unit mass of the hydrocarbon liquid; most preferably, in the range of 1.0 to 3.0% by mass per unit mass of the hydrocarbon liquid.

[0060] Method according to the sixth aspect of the present invention In a sixth aspect, the present invention provides a method for extending the operational life of a hydrocarbon liquid lubricant that is contaminated with nitrogen dioxide during operation. The method includes adding an ionic solution of the first aspect or an additive concentrate of the second aspect to the hydrocarbon lubricant prior to operation in an amount effective thereafter for reducing the coefficient of friction of the lubricant or improving its resistance to mechanical wear, or in an amount effective for chemically inactivating nitrogen dioxide incorporated into the hydrocarbon liquid lubricant and thereby inhibiting the formation of hydrocarbon nitrate esters in the lubricant, or both. In the method of the sixth embodiment, it is preferable that the ionic solution or additive concentrate is effective in both chemically inactivating nitrogen dioxide incorporated into the lubricant and reducing the coefficient of friction of the lubricant to improve resistance to mechanical wear. Most preferably, the uses of the fourth and fifth embodiments of the present invention, and the methods of the sixth embodiment, aim to limit the chemical decomposition and friction and / or wear of hydrocarbon fluids that constitute engine lubricants. These lubricants become contaminated with nitrogen dioxide during operation as exhaust gases blow from the combustion chamber through the piston rings into the crankcase. Such lubricants, also called crankcase oils, operate at bulk fluid temperatures where the nitrification pathway to oil decomposition becomes prominent, especially when the lubricant is fresh and aged oil components have not formed in large quantities by other mechanisms. Engines operating at relatively high temperatures are particularly susceptible to such decomposition, and engines operating under bulk crankcase oil temperature conditions or cycles of 110-160°C, especially 130-160°C, are particularly susceptible.

[0061] definition For the purposes of this specification and all claims relating to the present invention, the following words and expressions, when used, have the meanings attributed below. For the purposes of this specification, we refer to the new numbering scheme for the periodic table of elements as described in "CHEMICAL AND ENGINEERING NEWS," 1985, No. 63(5), 27. Alkali metals are Group 1 metals (e.g., Li, Na, K, etc.). Alkaline earth metals are Group 2 metals (e.g., Mg, Ca, Ba, etc.). The term “contains” or any synonym identifies the presence of the described feature, process, integer, or component, but does not exclude the presence or addition of one or more other features, processes, integers, components, or groups thereof. The expression “consistes of” or “basically consists of” or its synonyms may be included within the scope of “contains” or its synonyms, where “basically consists of” allows for the inclusion of substances that do not substantially affect the properties of the composition to which it applies.

[0062] The term "mass%" means the mass percentage of a component based on the mass of the composition measured in grams, unless otherwise specified, and is alternatively expressed as mass percentage ("mass%", "wt%", or "%w / w"). With respect to the components contained in the lubricating oil compositions described herein and in the claims therefor, the terms “not present” or “not present” mean that a particular component is present in 0% by mass relative to the mass of the lubricating oil composition, or, if present in the lubricating oil composition, that the component is present at a level that does not affect the properties of the lubricating oil composition, for example, less than 10 ppm, less than 1 ppm, or less than 0.001 ppm. With respect to the amounts of aging components and nitrogen dioxide contamination, the terms “not present” or “not present” mean a level that does not affect the properties of the lubricating oil composition, for example, less than 10 ppm, less than 1 ppm, or less than 0.001 ppm. Unless otherwise specified, all reported percentages are mass percentages relative to the active ingredient, i.e., mass percentages that do not take into account carriers or diluents unless otherwise stated.

[0063] The present invention further relates to the following: 1. It is an ionic solution: (i) One or more nitrogen-free organic cations comprising a central atom or ring system having a cationic charge and a plurality of pendant hydrocarbyl substituents, and (ii) One or more organic anions that do not contain halogens or boron, each containing a carboxylate functional group and an aromatic ring having a functional group further containing a heteroatom, wherein these functional groups are conjugated with the aromatic ring, this conjugated system has an anionic charge, and the aromatic ring further has one or more hydrocarbyl substituents; An ionic solution consisting of [the following]. 2. The ionic solution as described in paragraph 1, wherein each cation (i) of the ionic solution consists of a tetrahydrocarbyl-substituted central atom or ring system having a cationic charge. 3. The ionic solution according to paragraph 1 or 2, wherein each cation (i) in the ionic solution is a tetraalkyl-substituted phosphonium cation. 4. The ionic solution described in paragraph 3, in which each cation (i) is a trihexyltetradecylphosphonium cation. 5. Each anion (ii) in the ionic solution is nitrogen-free, and the ionic solution is one of the solutions described in paragraphs 1 to 4. 6. The ionic solution according to any one of paragraphs 1 to 5, wherein one or more hydrocarbyl substituents on the aromatic ring of each anion (ii) of the ionic solution are one or more linear or branched alkyl substituents. 7. The ionic solution described in paragraph 5, or paragraph 6 if paragraph 5 is interpreted as such, wherein one or more anions (ii) of the ionic solution are one or more alkyl-substituted salicylate anions, and each alkyl substituent (one or more) of each anion is independently selected from alkyl groups having 12 to 24 carbon atoms. 8. A hydrocarbon additive concentrate comprising an ionic solution described in any of paragraphs 1 to 7, and a carrier solution compatible with the ionic solution. 9. A hydrocarbon liquid containing an ionic solution or additive concentrate described in any of paragraphs 1 to 8, wherein the amount of the ionic solution is a maximum of 5.0% by mass of the hydrocarbon liquid. 10. The additive concentrate described in paragraph 8 or the hydrocarbon liquid described in paragraph 9 further comprises one or more performance-enhancing additives, preferably containing one or more of the following: phosphorus-containing compounds; dispersants; metal cleaning agents; anti-wear agents; friction modifiers, viscosity modifiers, antioxidants; metal rust inhibitors, viscosity index improvers, corrosion inhibitors, defoamers, and pour point depressants. 11. Use of an ionic solution described in any of paragraphs 1 to 7, or an additive concentrate described in paragraph 8 or 10, as an additive for hydrocarbon liquids to chemically inactivate nitrogen dioxide incorporated into the hydrocarbon liquid. 12. The ionic solution inhibits the formation of hydrocarbon nitrate esters, thereby extending the operational life of the hydrocarbon solution, as described in paragraph 11. 13. Use of ionic solutions described in any of paragraphs 1 to 7 or additive concentrates of paragraphs 8 or 10 as additives for hydrocarbon liquid lubricants to reduce the coefficient of friction of the lubricant, improve resistance to mechanical wear, or both. 14. The ionic solution also chemically inactivates nitrogen dioxide incorporated into the hydrocarbon lubricant, as described in paragraph 13. 15. The ionic solution inhibits the increase in the total acid number, as measured according to ASTM D664, in hydrocarbon lubricants during operation, as described in paragraph 14. 16. A method for extending the operational life of a hydrocarbon liquid lubricant that is contaminated with nitrogen dioxide during operation, the method comprising the step of adding an ionic solution described in any of paragraphs 1 to 8 or an additive concentrate described in paragraph 8 or 10 to the hydrocarbon liquid lubricant before operation, wherein the amount added is an amount effective in subsequently reducing the coefficient of friction of the lubricant or improving its resistance to mechanical wear, or an amount effective in chemically inactivating nitrogen dioxide incorporated into the hydrocarbon liquid lubricant, thereby inhibiting the formation of hydrocarbon nitrate esters, or an amount effective in doing both. 17. The method according to paragraph 16, wherein the ionic solution or additive concentrate is effective both in chemically inactivating nitrogen dioxide incorporated into the lubricant and in reducing the coefficient of friction of the lubricant to improve resistance to mechanical wear. 18. A method for extending the operational life of a hydrocarbon liquid lubricant that is contaminated with nitrogen dioxide during operation, the method comprising the step of adding an ionic solution described in any of paragraphs 1 to 7 or a concentrate described in paragraph 8 or 10 to the hydrocarbon liquid lubricant prior to operation, wherein the amount added is an amount effective in obtaining one, two, or three of the following effects thereafter: 1) The effect of lubricants on reducing the coefficient of friction; 2) The effect of improving resistance to mechanical wear; and 3) Chemically inactivates nitrogen dioxide incorporated into hydrocarbon liquid lubricants, thereby inhibiting the formation of hydrocarbon nitrate esters in the hydrocarbon liquid lubricants. The method. 19. The ionic solution is: Chemically inactivating nitrogen dioxide incorporated into the lubricant; Reducing the coefficient of friction of the lubricant; and To improve resistance to mechanical wear. The method described in paragraph 18 is effective for [the purpose of the invention]. [Examples]

[0064] The implementation and advantages of the present invention will be described below with reference to examples. For the purposes of the present invention and the claims thereto, the amount of reduction or limitation of nitrate ester formation in a lubricating oil composition is determined by observing that the nitrate ester peak height in the presence of the lubricating oil composition containing the ionic solution is lower (e.g., at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 100%) compared to the nitrate ester peak of the same lubricating oil composition in which the ionic solution is replaced with an ionic solution having the same cation but the same proportion of hexanoate as anion. This peak height is measured by infrared spectroscopy in accordance with DIN51 453 or ASTM D8048-20 under similar operating and nitrogen dioxide contamination conditions, provided that if there is a discrepancy between DIN51 453 and ASTM D8048-20, DIN51 453 shall be followed.

[0065] Preparation Example - Preparation of Ionic Solution The ionic solution was synthesized using the following method, which incorporates an ion exchange resin.

[0066] Example 1: [P66614] [Alkyl salicylate] (Example of the present invention) [P66614][alkyl-salicylate] was produced using a two-step synthesis method starting with commercially available trihexyltetradecylphosphonium chloride, [P66614]Cl (CYPHOS IL-101, >95%, CAS number: 258864-54-9). In the first stage, [P66614][OH] was synthesized from [P66614]Cl using a commercially available basic anion exchange resin (Amberlite IRN-78, OH-form resin, CAS number: 11128-95-3). [P66614]Cl (100 g, 0.193 mol) was added to a 2 L round-bottom flask and diluted with anhydrous ethanol (900 mL, 19.5 mol, CAS number: 64-17-5). 100 g of ion exchange resin was added to this mixture, and the mixture was stirred at 22°C for 5 hours. The resin was then filtered off, and 100 g of fresh resin was added. This process was repeated three times, or until a negative result was observed in the silver halide test, indicating the completion of ion exchange. The silver halide test was performed as follows: A small aliquot (0.2 mL) of the reaction mixture was transferred to a 2 mL vial and diluted with 1 mL of anhydrous ethanol. Two to three drops of HNO3 were added to acidify the solution, and then two to three drops of saturated aqueous solution of AgNO3 (≧99% by mass, Sigma-Aldrich, CAS number: 7761-88-8) were added. When a clear solution without precipitates was observed, it was determined that ion exchange was complete. In the second stage, 1 The concentration of [P66614][OH] in ethanol was measured by 1H NMR. Next, commercially available alkyl-salicylic acid from Infineum UK, a monoalkylsalicylic acid mixture having alkyl substituents with 14 and 16 carbon atoms, was added dropwise to 100 mL of ethanol in equimolar amounts and dissolved. The acid value of the alkyl-salicylic acid (0.00261 gH) was then measured. + Using the molar formula, the amount of acid required for the neutralization reaction with [P66614][OH] (equimolar - equivalent to 73.96 g of alkyl salicylic acid) was calculated, and then this mixture was stirred overnight at 22°C. Next, this solution was dried under rotary evaporation and then heated under reduced pressure (10°C). -3 Drying at Pa, 50°C for 96 hours or more was performed to obtain a dry pure ionic solution. After drying, the ionic liquid material was characterized by NMR: [P66614] [Alkyl salicylate]: 1 H NMR (500MHz, DMSO‐d6): δ(ppm)= 0.69~0.88(s),1.04~1.29(m),1.37(m),1.46(m),2.15(m),2.29(s),3.34(s),3.43(m),4.36(s),6.49(m),6.7 2(m),6.93(m),7.18(m),7.25(m),7.41(s),7.47(m),7.65(s),7.70(s),8.16(s),9.07(s),9.11(s),9.15(s).

[0067] Another sample of [P66614][alkyl-salicylate] was prepared using the following scaled-up procedure. [P66614]Cl (808 g, 1.56 mol) was packed into a 5 L glass reactor and diluted with anhydrous ethanol (770 mL, 13.2 mol). Using a water bath to limit the exothermic reaction to 23°C, a pre-prepared solution of KOH (87.3 g, 1.56 mol) in anhydrous ethanol (770 mL, 13.2 mol) was added to this solution over 28 minutes. This mixture was aged for 90 to 250 minutes, blended with Celite filter aid (164 g, 20% by mass), filtered to remove KCl, and the filtered cake was rinsed with anhydrous ethanol (160 mL, 2.74 mol). The filtrate was transferred to a clean 5 L glass reactor and treated with Amberlite ion exchange resin IRN-78 (400 g, 50% by mass) for 30 to 70 minutes. After filtration separation, the resin was rinsed with anhydrous ethanol (2 × 160 mL, 2 × 2.74 mol). The filtrate was transferred to a clean 5L glass reactor, and using a water bath to limit the heat generation to 28°C, equimolar amounts of the same alkyl-salicylic acid were added to the filtrate as a xylene solution over 33 minutes. After aging this mixture for 16 hours, volatile components were removed by rotary evaporation at 60-80°C and 10 mbar over 3 hours or more.

[0068] Example 2: [P66614] [Hexane salt] (Comparative example) [P66614][hexanoate] was synthesized using the procedure used for [P66614][alkyl-salicylate] in Example 1.1. First, [P66614][OH] was prepared from [P66614]Cl (100 g, 0.193 mol). In the second step, hexanoic acid (≧99% by mass, CAS number: 142-62-1) was added equimolarly instead of salicylic acid (22.4 g, 0.193 mol) to produce the desired ionic solution, which was then dried.

[0069] Example 3: [P66614][NTf2] (Comparative Example) Trihexyltetradecylphosphonium chloride, [P66614]Cl (100 g, 0.193 mol) was dissolved in a minimum amount of dichloromethane (>99%, CAS number: 75-09-2) in a 1 L round-bottom flask. A commercially available aqueous solution of LiNTf2 (55.3 g, 0.193 mol; 99% by mass, CAS number: 90076-65-6) was added dropwise. The reaction mixture was stirred at 22°C for 12 hours to form a biphasic solution. The organic layer was extracted and washed five times with ultrapure water to remove LiCl by-products, and washing was continued until a negative result was confirmed by the halide test. The solution was then dried under rotary evaporation and evaporated under reduced pressure (10°C). -3 The mixture was dried at Pa, 50°C for 96 hours or more to obtain dried pure trihexyltetradecylphosphonium bis(trifluoromethanesulfonyl)imide, [P66614][NTf2], and determined by NMR as follows: [P66614][NTf2]: 1 H NMR (500MHz, CDCl3): δ(ppm)=0.88(m,12H,CH3--(P)),1.23~1.29(m,32H,-CH2-(P)),1.46(m,16H,-CH2-(P)),2.08(m,8H,-CH2-(P)); 13 C NMR(126MHz,CDCl3):δ(ppm)=13.85,14.12,18.56,18.94,21.55,22.28,22.69, 28.80,29.25,29.36,29.49,29.65,30.17,30.52,30.89,31.92,118.62,121.17. The ionic solutions prepared by these synthesis methods were used in the following further examples.

[0070] Research Example 1 - Mechanistic Evaluation of the Ionic Solution of the Present Invention To evaluate the effects and mechanisms of the ionic solution of the present invention, the initiation and progression of nitrification in a hydrocarbon solution contaminated with nitrogen dioxide can be observed and measured by infrared spectroscopy. Monitoring the ongoing nitrification of hydrocarbon liquids involves periodically taking samples of the liquid in use under actual or simulated operating conditions, and tracking the progression of the nitrification peak height in the fingerprint region of the infrared spectrum. The rate of increase in nitrification peak height provides information about the rate of nitrification in the bulk liquid and the chemical decomposition due to the accumulation of nitrate ester storage. According to the DIN 51453 peak height method [Standard DIN 51453 (2004-10): Testing of lubricants - Determination of oxidation and nitrification of used motor oil - Infrared spectroscopy], a peak height of 1630 cm is due to the formation of hydrocarbon nitrate esters. -1 The height of the single infrared absorption frequency is 1615 cm². -1 and 1645cm -1 It is measured higher than the linear baseline defined by absorption. The higher the peak height, the more hydrocarbon nitrate esters are present in the bulk liquid. According to the DIN method described above, the 1710 cm is due to the carbonyl moiety (ketones, aldehydes, esters, and carboxylic acids) formed as a result of oxidation. -1 By measuring the peak height, the conventional oxidation process of the bulk liquid can also be monitored. This peak height is 1970 cm. -1 and 1650cm -1 The absorption is measured relative to a linear baseline defined by the absorption at [location]. Here again, the rate of increase in peak height provides information about the rate of chemical oxidation in the bulk liquid. In accordance with the ASTM D8048-20 standard test method for evaluating diesel engine oil in Volvo (Mack) T-13 diesel engines, oxidation and nitrification peak heights are measured by first subtracting the infrared spectrum of a new oil. The baseline is 1950 cm². -1 ~1850cm -1 Defined by absorption, the highest peak is at 1740 cm⁻¹ in oxidation. -1 ~1700cm -1 Within the range of nitrification, 1640 cm -1 ~1620cm -1 It is within the range. Samples of hydrocarbon liquids tested under operating conditions can be measured by the method described above, and the effects of different ionic solutions present in the hydrocarbon liquid on the progress of nitrification and oxidation, as well as the level of inhibition of such decomposition, can be reported.

[0071] Contribution of anions to the inhibition of nitrification-induced decomposition To illustrate the contribution of the anion in the ionic solution to the performance of the present invention, the DIN 51453 method was used. A newly prepared lubricating oil was tested as a bulk hydrocarbon liquid, and this composition contained a conventional package of commercially available additives. To this starting oil composition, the ionic solution of Example 1 of the present invention, consisting of a tetraalkylphosphonium cation "P66614" and an alkyl salicylate anion, was added at 2% by mass relative to the mass of the oil. Comparative test samples were prepared from the same starting oil composition by adding the ionic solution of Example 3, which has the same P66614 cation but contains an NTf2 anion [trihexyltetradecylphosphonium bis(trifluoromethanesulfonyl)imide], at 2% by mass per unit of oil mass. Therefore, this comparative ionic solution contains anion of a type suitable for conventional antioxidant properties as specified in U.S. Patent No. 2010 / 0187481. The starting oil composition was also used as a control run to establish a baseline provided by commercially available blended oils.

[0072] The test samples were used as engine lubricants for laboratory simulations of operating conditions. Here, the lubricant was exposed to the operating temperature of an oil reservoir and to a nitrogen dioxide source to simulate contamination during operation. The simulation used a 250 mL three-neck conical flask equipped with a glycol concentrator and heated on an electric hot plate. A gas containing 766 ppm NO2 from air was foamed with 250 g of the test lubricant at a rate of 10 liters per minute. Sintered glass frit was used to disperse the gas in the lubricant. The gas flow rate was controlled using a mass flow controller. A thermocouple was introduced from the third neck back to the hot plate to maintain a constant temperature. Each test sample was operated at 130°C for 96 hours, and the nitrification and oxidation peak heights were measured at the end of the test using the DIN 51453 method described above. The results for two samples containing ionic solutions were then compared to a control oil formulation, and the effect of each ionic solution was reported as a percentage reduction in nitrification and oxidation peak height compared to the control. result [Table 2]

[0073] The presence of the P66614 alkyl-salicylate ion solution of the present invention resulted in a significantly lower nitrification peak height compared to a comparative ion solution with the same cation but an anion not conforming to the present invention. These results support the existence of a difference in the effect of the anion composition in the ion solution and demonstrate that the anion defined in the present invention provides a significant advantage in inactivating nitrogen dioxide incorporated into the bulk liquid. Although the present invention also showed a significant reduction in oxidation peak height, the oxidation results were not significantly different between the two ionic solution samples, which supports the existence of various chemical pathways for nitrification and classical oxidation of the lubricant. The differences in the advantages of the present invention for nitrification demonstrated high selectivity for inhibiting the nitrification pathway during operation and high suitability for controlling the effects of nitrogen dioxide contamination.

[0074] The contribution of cations to inhibiting nitrification-induced decomposition. To explain the contribution of the cation of the ionic solution to the performance of the present invention, the DIN 51453 method and laboratory test methods for anion comparison described above were used. The tests were again conducted on a newly prepared blended lubricating oil as a bulk hydrocarbon liquid containing a conventional package of commercially available additives. To this starting composition, the ionic solution of Example 1 of the present invention, consisting of a tetraalkylphosphonium cation "P66614" and an alkyl salicylate anion, was added at a rate of 2% by mass per unit of oil mass. However, the comparative test sample was prepared from the same starting oil composition by adding alkyl salicylic acid for preparing the ionic solution in an amount equivalent to the amount of anion in the ionic solution sample. Therefore, in this case, the same aromatic ring structure was added to the oil in the same amount, but no cation was added. The starting oil composition was used again as a control. Test samples were subjected to laboratory simulations under the same operating conditions as engine lubricants. To simulate contamination during operation, the lubricants were exposed to the operating temperature of an oil reservoir and to a nitrogen dioxide source. Each test sample was operated at 130°C for 96 hours, and the nitrification and oxidation peak heights were measured at the end of the test using the DIN method described above. The results of the two samples were then compared with a control lubricant, and the effect was reported as a percentage reduction in nitrification and oxidation peak heights compared to the control lubricant. [Table 3]

[0075] These results revealed that while alkyl salicylic acid itself reduces nitrification to some extent, the ionic solution is a more potent nitrification inhibitor. This performance advantage was far more pronounced in nitrification than in oxidation. Therefore, the complete nitrification inhibitory effect of the ionic solution of the present invention is due to the combination of ion pairs in the ionic solution that cooperate to inactivate nitrogen dioxide present in the bulk liquid. The mechanism of this combined effect was further investigated in the same laboratory simulation test using the same newly prepared lubricating oil composition, this time treated with the ionic solution P66614Cl. This comparative ionic solution did not reduce the nitrification peak height as much as the example of alkyl salicylate of the present invention, but it still reduced the nitrification level by more than 60% compared to the control without this ionic solution. Compositional analysis of the bulk oil composition at the end of the test showed a decrease in chloride concentration in the oil during the test period; and gas purging through the bulk oil to the silver nitrate solution at the end of the test confirmed the formation of hydrochloric acid during the test. Therefore, it is thought that the P66614 cation forms a complex with nitric acid formed in situ from some of the nitrogen dioxide, and this complex is rearranged into a P66614-nitrate ion pair, releasing HCl. In this way, the cations in the ionic solution also act to confine some of the nitrogen dioxide in an inactive form, reducing the effective level of contaminants and consequently slowing down decomposition. Accordingly, in the implementation of the present invention, the advantages of the defined ionic solution are due to the synergistic effect of the particularly high affinity of a given anion for isolating nitrogen dioxide and the ability of the associated cation to form a stable complex with nitrate ions formed in situ from a portion of the nitrogen dioxide. This effect further reduces the concentration of actionable nitrogen dioxide in the bulk liquid. This combined effect particularly effectively inhibits nitrification and subsequent decomposition by nitrogen dioxide in the bulk liquid. This effect also slows the increase in the total acid value in the bulk liquid, reducing the likelihood of nitrification and acidification resulting in increased bulk liquid viscosity.

[0076] Research Example 2 – Performance of the present invention in controlling decomposition under operating conditions The advantageous properties of the present invention will be explained by tests conducted under actual operating conditions. For these purposes, engine lubricating oil was used as the hydrocarbon fluid. The selected operating environment was the ASTM D8048-20 standard test procedure for evaluating diesel engine oil in a Volvo (Mack) T-13 diesel engine. This test used a 2010 Volvo / Mack D13 / MP8, 505 BHP, 13L inline 6-cylinder diesel engine, which is equipped with electronically controlled fuel injection, six electronic unit injectors, a VGT (variable displacement turbocharger), and a cooled EGR (exhaust gas recirculation) system. The test consisted of a 360-hour test run under steady-state conditions of 1500 rpm, torque of approximately 2200 Nm, oil temperature of 130°C, and 19-20% EGR. The main objective was to evaluate the oxidation stability performance of engine oil at high oil temperatures using ULSD (ultra-low sulfur diesel) fuel. The tests for lubricant quality were conducted according to the following industrial specifications: Mack EOS-4.5, Volvo EOS-4.5, Renault RLD-4, API CK-4, and FA-4. The T13 engine test was selected because its characteristics, known in the art, are typically high operating temperatures and NOx emissions from the engine. Accordingly, the engine (crankcase) lubricating oil in the T13 test was exposed to high bulk temperatures in the oil reservoir during operation, as well as nitrogen dioxide contamination due to direct intake of lubricant flowing from the cylinder walls, and exhaust gases blown through the piston rings into the crankcase. The T13 test tests the durability of lubricants under conditions that promote chemical decomposition by nitrification, which initiates nitrogen dioxide contamination. To enhance the durability element of this test, the normal duration of 360 hours was extended to 400 hours in some of the following examples. During the test, the lubricant was periodically sampled, and the nitrification and oxidation peak heights were measured by infrared spectroscopy using the ASTM D8048-20 Mack (Volvo) T13 oxidation method described in Application 3 above. The increase in the total acid number (TAN ASTM D445) during the test, as well as the increase in the viscosity of the lubricant (ASTM D445) at 40°C and 100°C during the test, were also measured.

[0077] Three T13 tests were conducted to compare the effects of different additives on controlling chemical decomposition by nitrification and final oxidation. In each case, the same newly prepared starting lubricant composition was used, which was a standard lubricant base oil base stock containing a standard commercially available additive package. In each test, one additional material was added to this starting composition, and the effects of these materials were compared. In oil formulation 1 (comparative example), the additional material is a tetraalkylphosphonium cation "P66614" and a hexanoate anion, i.e., a structure YCOO( where Y is C6 alkyl). ‐ This was a prior art comparative ionic solution consisting of the anions of ). This ionic solution was used at a processing rate of 2% by mass per unit mass of the lubricating oil composition and was produced in Preparation Example 2 described herein. In oil formulation 2 (comparative example), the additional material was a commercially available antioxidant additive consisting of a hindered phenol compound. This material is known to be an effective counter to conventional free radical oxidation processes. In oil formulation 3 (the present invention), the additional material was the ionic solution of the present invention, consisting of a tetraalkylphosphonium cation "P66614" and an alkyl salicylate anion. This ionic solution was used in the lubricating oil composition at an equimolar concentration with the P66614-hexanoate ionic solution used in the first example, and the treatment rate per unit mass of the lubricating oil composition was approximately 2.8% by mass. This ionic solution was produced by a scaled-up method of Preparation Example 1 described herein.

[0078] The results of the T13 test process are shown graphically in Figures 1, 2, and 3 for nitrification, oxidation, and increase in kinematic viscosity at 100°C, respectively. In Figure 1, all three test compositions showed an increase in nitrification peak height as the test progressed, indicating some nitrification due to nitrogen dioxide contamination. However, oil composition 2, which contains a conventional antioxidant, showed the fastest overall increase in nitrification peak height, and this rate accelerated from 300 hours into the test. Therefore, this test run was stopped at the normal 360-hour point, when the nitrification peak height exceeds 40. In the ionic solution-treated oils 1 and 3, nitrification progressed generally slowly. However, even in the hexanoate-based ionic solution (oil 1), the nitrification rate increased from 200 hours, and by 360 hours, the nitrification peak height exceeded 30. In contrast, the alkyl salicylate-based ionic solution (oil 3) maintained a gentle and stable gradient throughout the entire normal duration of 360 hours, with the nitrification peak height only exceeding 20 at this point. This was less than half the nitrification of the conventional antioxidant oil 2 and substantially lower than that of oil 1. By 400 hours, the nitrification level of oil 3 was still significantly lower than that of oil 1. Thus, under actual engine operating conditions, including high oil reservoir temperatures and the presence of nitrogen dioxide contamination, the present invention demonstrated a substantially improved ability to inhibit nitrification compared to conventional antioxidant additive solutions. Furthermore, the performance was significantly improved compared to similar alkyl-carboxylate ion solutions, demonstrating the advantages derived from the different composition.

[0079] Similarly, Figure 2 shows that oxidation increased rapidly as the test neared its end in both the conventional antioxidant solution (oil 2) and the hexanoate-based ionic solution (oil 1), with the oils losing oxidation control and showing a sharp rise in oxidation peak height. In contrast, oil 3 maintained superior oxidation control throughout, up to 360 hours, and still showed significantly lower oxidation than both comparison oils up to 400 hours. The slow increase in nitrification peak height, and consequently oxidation peak height, exhibited by oil agent 3 similarly demonstrates the superior effectiveness of the present invention in inhibiting the chemical decomposition of bulk liquid (lubricating oil) caused by nitrogen dioxide contamination during operation. The slow increase in nitrification peak height over time dramatically delays the accumulation of nitrate esters in the bulk liquid, thereby delaying the onset of chemical decomposition by nitrification and extending the operating period of the liquid. The increase in kinematic viscosity (measured by ASTM D445) during the test process shown in Figure 3 differed between the two ionic solutions. The kinematic viscosity of oil 1 increased sharply towards the end of the test because this oil lost control of its decomposition process. In contrast, oil 3 of the present invention maintained a virtually constant viscosity throughout the entire test. To avoid introducing other uncertainties, the initial viscosity increase of the ionic solution-treated oil in these tests occurred due to the direct viscosity effect of adding the ionic solution to the base oil composition without adjustment, and this initial viscosity increase is formulated in the implementation of the present invention by adjusting the viscosity of the base oil composition.

[0080] The present invention also demonstrated improved TAN control compared to similar hexanoate-based ionic solutions. At the end of the test, the TAN of oil 3 was only 2.8 at the end of the normal 360-hour test and 4.2 at the end of the extended 400-hour test; on the other hand, the TAN of oil 1 had already risen to 8.32 by 360 hours, so this test was not extended further. Thus, the present invention (oil agent 3) is advantageous in terms of both viscosity control and total acid value control, and also provides users with advantages in terms of formulation.

[0081] Research Example 3: Friction and wear reduction performance of ionic solutions The following industrial tests demonstrated the ability of the ionic solution of the present invention to reduce the coefficient of friction and decrease wear on contact surfaces lubricated with hydrocarbon liquid. Both the coefficient of friction and the volume of wear marks were measured using a high-frequency reciprocating rig (HFRR) test. In this test, a steel plate is immersed in a liquid lubricant and reciprocated towards a steel ball under standard conditions. This test used a commercially available HFRR machine equipped with a 10 mm test disc of SAE-AMS6440 steel (AISO52100 / 535A99) with a surface roughness (Ra) <0.2 μm and a hardness of 190-210 (Vickers hardness (Hv) 30), and a 6.00 mm test ball of SAE-AMS6440 steel (grade 28 according to ISO3290) with a surface roughness <0.5 μm and a hardness of 58-66 on the Rockwell "C" scale. The test was performed according to the following profile: the test specimen was subjected to a series of temperature-increasing steps at 40, 60, 80, 100, 120, and 140°C. In each step, the test specimen was kept constant at that temperature for 1 minute, and then, at that stable temperature, a reciprocating cycle was performed for 5 minutes with a load of 400g, a frequency of 40Hz, a stroke length of 1000μm, and an output interval of 5 seconds. After that, the sample temperature was increased before the next step, and the reciprocating cycle was repeated until all temperature steps were completed. The coefficient of friction was measured during the test, and the wear mark volume was determined at the end of the test. The coefficient of friction was also measured using the TE-77 test method, which involves cutting test specimens from uncoated steel top rings and steel liners used in the DD13 engine test. The temperature was kept constant at 150°C throughout the test, and the reciprocating frequency was kept constant at 10Hz throughout the test.

[0082] In the test profile, the system was operated with a load of 20N for 5 minutes, then the load was gradually increased from 20N to 200N at a rate of 1.5N / min (process time approximately 2 hours), and the load was then kept constant at 200N for another hour. Furthermore, the wear mark volume is also measured using the MTM-R test. This test used a commercially available MTM apparatus equipped with a 46 mm AISI52100 steel test disc with a surface finish Ra of <0.02 μm and a hardness of 720-780 Hv, and a 19.05 mm AISI52100 steel test ball with a surface finish Ra of <0.02 μm and a hardness of 800-920 Hv. In the test profile, the stroke length was 4 mm, and the maximum force (Fmax) at position 5 was 20 N. During the reciprocating sphere on the disc process, the sphere velocity was 350 m / s at a frequency of 10 Hz, and the test temperature was stabilized at 100 °C. The process duration was 45 minutes, and the logging interval was 10 seconds. A hydrocarbon-based lubricating engine oil containing a typical package of commercially available oil additives ("baseline" oil formulation) was tested according to the method described above. This test was performed with and without the presence of Example 1 of the present invention, at an amount of 2% by mass per unit mass of the baseline oil formulation. The effect of the ionic solution was directly observed through these comparisons. The results are shown in Figures 5 to 8. Figures 4 and 5 show how the introduction of the ionic solution in Example 1 lowers the coefficient of friction in the HFRR and TE-77 tests. In the TE-77 test, the coefficient of friction achieved in the presence of Example 1 remained lower than that of the baseline oil formulation throughout the entire test sequence. In the HFRR test, the coefficient of friction diverged throughout the test process with and without Example 1, while the ionic solution maintained a constant friction level over time.

[0083] Figures 6 and 7 show that the presence of Example 1 reduced the wear mark volume in both the MTM-R and HFRR tests, respectively, indicating that the ionic solution of the present invention is also effective in reducing wear on contact surfaces lubricated by the oil. Tracking fuel consumption tests conducted on an engine rig with an M276 motor using the ionic solution of Example 1 at a concentration of 1% by mass per unit of lubricating oil demonstrated torque reductions of 0.5% and 0.7% at medium, high, and ultra-high temperatures, confirming the ionic solution's ability to provide frictional benefits that translate into measurable advantages in engine performance. Accordingly, the above embodiments demonstrate that when the ionic solution of the present invention is used as an additive for hydrocarbon solutions, it possesses the advantages of performance, such as reducing the chemical decomposition of hydrocarbon solutions by inhibiting the formation of hydrocarbon-based nitrate esters resulting from nitrogen dioxide contamination, and reducing friction and / or wear between contact surfaces lubricated by the hydrocarbon solution. Furthermore, consequential advantages such as inhibiting the increase in viscosity or acid value during operation and improving fuel efficiency are also observed.

[0084] All documents described herein, to the extent that they do not contradict the text, are incorporated herein by reference, including any priority documents and / or test procedures. While embodiments of the present invention have been illustrated and described, as will be apparent from the general description and specific embodiments, various modifications are possible without departing from the spirit and scope of the invention. Therefore, the invention is not intended to be limited by modifications. The term “comprising” identifies the presence of a described feature, process, integer, or component, but does not exclude the presence or addition of one or more other features, processes, integers, components, or groups thereof. Similarly, the term “comprising” is considered synonymous with the term “including.” Similarly, whenever a transitional phrase “comprising” precedes a composition, element, or group of elements, it should be understood that the same composition or group of elements may also be preceded by the transitional phrases “basically consisting of,” “consisting of,” “selected from a group consisting of,” or “is,” and vice versa. Furthermore, if a range is described as "between A and B," that range includes both endpoints A and B, so "between A and B" is synonymous with "from A to B."

Claims

1. An ionic liquid comprising: (i) one or more nitrogen-free organic cations, each containing a central atom or ring system bearing a cationic charge and a plurality of pendant hydrocarbyl substituents; and (ii) one or more halogen- and boron-free organic anions each containing an aromatic ring bearing a carboxylate functional group and a further heteroatom-containing functional group, which functional groups are conjugated with said aromatic ring, this conjugated system carrying an anionic charge, and said aromatic ring further bearing one or more hydrocarbyl substituents; An ionic liquid comprising:

2. 2. The ionic liquid of claim 1, wherein each said cation (i) of said ionic liquid comprises a tetrahydrocarbyl-substituted central atom or ring system bearing a cationic charge.

3. 10. The ionic liquid of claim 1, wherein each said cation (i) of said ionic liquid is a tetraalkyl-substituted phosphonium cation.

4. 2. The ionic liquid of claim 1, wherein each said cation (i) is a trihexyltetradecylphosphonium cation.

5. 10. The ionic liquid of claim 1, wherein each anion (ii) of the ionic liquid is nitrogen-free.

6. 10. The ionic liquid of claim 1, wherein the one or more hydrocarbyl substituents on the aromatic ring of each anion (ii) of the ionic liquid are one or more straight or branched chain alkyl substituents.

7. 6. The ionic liquid of claim 5, wherein the one or more anions (ii) of the ionic liquid are one or more alkyl-substituted salicylate anions, and the alkyl substituents of each anion are each independently selected from alkyl groups containing from 12 to 24 carbon atoms.

8. 7. The ionic liquid of claim 6, wherein each anion (ii) of the ionic liquid does not contain nitrogen, and wherein the one or more anions (ii) of the ionic liquid are one or more alkyl-substituted salicylate anions, and wherein the alkyl substituents of each anion are each independently selected from alkyl groups having from 12 to 24 carbon atoms.

9. A hydrocarbon liquid comprising the ionic liquid according to any one of claims 1 to 8, wherein the amount of the ionic liquid is up to 5.0% by mass based on the mass of the hydrocarbon liquid.

10. An additive concentrate for hydrocarbon liquids comprising the ionic liquid of any one of claims 1 to 8 and a carrier liquid compatible with the ionic liquid.

11. 11. The additive concentrate of claim 10, further comprising one or more performance-enhancing additives including one or more of: phosphorus-containing compounds; dispersants; metal detergents; anti-wear agents; friction modifiers, viscosity modifiers, antioxidants; metal rust inhibitors, viscosity index improvers, corrosion inhibitors, anti-foam agents, and pour point depressants.

12. Use of an ionic liquid according to any one of claims 1 to 8 as an additive for a hydrocarbon liquid to chemically inactivate nitrogen dioxide entrapped within said hydrocarbon liquid.

13. 13. The use of the ionic liquid of claim 12, wherein the ionic liquid results in inhibition of the formation of hydrocarbon-based nitrates, thereby extending the operational life of the hydrocarbon liquid.

14. 9. Use of an ionic liquid according to any one of claims 1 to 8 as an additive for a hydrocarbon-based liquid lubricant to reduce the coefficient of friction of said hydrocarbon-based liquid lubricant, improve its resistance to mechanical wear, or both.

15. 15. The use of claim 14, wherein the ionic liquid also chemically deactivates nitrogen dioxide entrapped within the hydrocarbon-based lubricant.

16. 15. The use of claim 14, wherein the ionic liquid inhibits the increase in total acid number, as measured in accordance with ASTM D664, in the hydrocarbon-based lubricant during operation.

17. 10. A method for extending the service life of a hydrocarbon-based liquid lubricant that is subject to nitrogen dioxide contamination during operation, the method comprising the step of adding the ionic liquid of any one of claims 1 to 8 to the hydrocarbon-based liquid lubricant prior to operation, in an amount thereafter effective to achieve one, two or three of the following effects: a) reducing the coefficient of friction of the lubricant; b) improving the resistance of the lubricant to mechanical wear; and c) Chemically inactivating nitrogen dioxide trapped in the hydrocarbon-based liquid lubricant, thereby inhibiting the formation of hydrocarbon-based nitrate esters in the hydrocarbon-based liquid lubricant. That's the method.

18. 18. The method of claim 17, wherein the ionic liquid is effective to chemically deactivate nitrogen dioxide entrapped within the lubricant and to reduce the coefficient of friction of the lubricant to improve its resistance to mechanical wear.

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