Oil-soluble ionic liquid with anti-corrosion and friction-reducing properties, preparation method and application thereof

Abstract

The present application provides an oil-soluble ionic liquid with anti-corrosion and friction-reducing properties, as well as its preparation method and application. The cation of the oil-soluble ionic liquid is a quaternary phosphonium cation of different alkyl chain lengths with a benzotriazole functional group, and the anion is sodium diisooctyl sulfosuccinate. The preparation method of the ionic liquid is as follows: chloromethylbenzotriazole and trioctylphosphine are mixed, and a quaternary phosphonium reaction is performed to obtain trioctylphosphonium functionalized with benzotriazole; then the trioctylphosphonium functionalized with benzotriazole is mixed with sodium docusate, and an ion exchange reaction is performed to obtain an oil-soluble ionic liquid. The oil-soluble ionic liquid is used as a lubricating additive for base oil PAO10 and is applied to the lubrication of steel / steel friction pairs. Experimental results show that the oil-soluble ionic liquid has good solubility in base oil PAO10, and at the same time, it not only has excellent friction-reducing and anti-wear properties on the steel / steel friction pair interface, but also has a good corrosion inhibition effect on the friction pair interface.

Description

Technical Field

[0001] The present application relates to the technical field of lubricating materials, and in particular to an oil-soluble ionic liquid with anti-corrosion and friction-reducing properties, and a preparation method and application thereof. Background Art

[0002] As an important member of the lubrication system, lubricating grease plays a vital role in various service conditions. However, with the continuous development of modern aerospace and space technology, new requirements have been put forward for the lubricating properties of lubricating grease. Traditional lubricating grease can no longer meet the lubrication and protection requirements of lubricated parts under harsh conditions. For this reason, the design and synthesis of new and efficient lubricants have attracted more and more attention. In 2001, the applicant's research group first reported that this type of material with low volatility, non-flammability, high thermal stability, low melting point and good electrical conductivity has excellent lubricating properties as a lubricant (CF Ye, WM Liu, YX Chen, et al, Chem. Commu, 21 (2001) 2244-2245.).

[0003] Since then, the scientific research on ionic liquids as lubricants and additives has become an independent and new research direction that has attracted widespread attention from international peers. The applicant's research group has long been committed to the synthesis and performance research of functionalized ionic liquids. The applicant grafted phosphate functional groups onto imidazole rings through molecular design, and the prepared ionic liquids showed relatively high lubrication performance for aluminum (ZGMu, F.Zhou, SXZhang, et al, Tribol.Inter.2005, 38(8), 725-731.). Although ionic liquids have better friction reduction and anti-wear properties than other synthetic lubricants, in the process of application research of ionic liquids, it was found that they still have some problems as lubricant additives, such as high preparation cost, corrosion of metal substrates, poor compatibility with commonly used lubricants, etc., which greatly restrict their industrial application. After investigation, it was found that there are currently few reports on functionalized ionic liquids with both good corrosion resistance and oil solubility. The applicants previously synthesized a class of quaternary phosphonium salt ionic liquids and used them as lubricants for steel / aluminum friction pairs, demonstrating their excellent friction reduction and anti-wear properties (XQ Liu, F. Zhou, YM Liang, et al., Wear 261 (2006) 1174–1179). We explored whether it would be possible to improve their oil solubility by varying the alkyl chain length and enhance their corrosion resistance as a base oil by grafting benzotriazole functional groups. To this end, combining previous work, we designed and prepared a series of benzotriazole-functionalized quaternary phosphonium salt ionic liquids, which effectively reduce base oil corrosion on metals, inhibit carbon deposit formation, and improve the lubricity of base oils. Summary of the Invention

[0004] The present application provides an oil-soluble ionic liquid with anti-corrosion and friction-reducing properties, and a preparation method and application thereof, to solve the above-mentioned problems mentioned in the background technology.

[0005] In one aspect, the present application provides an oil-soluble ionic liquid having anti-corrosion and friction-reducing properties, wherein the oil-soluble ionic liquid has the following general formula:

[0006]

[0007] Wherein R, R1 are independently selected from C1-C 18 of alkyl.

[0008] Optionally, R and R1 are independently selected from any one of methyl, ethyl, propyl, butyl, isobutyl, pentyl, isopentyl, octyl, isooctyl, decyl, isodecyl, dodecyl, tetradecyl, hexadecyl and octadecyl.

[0009] On the other hand, the present application provides a method for preparing an oil-soluble ionic liquid having anti-corrosion and friction-reducing properties, which is used to prepare the above-mentioned oil-soluble ionic liquid, and the preparation method comprises the following steps:

[0010] (1) mixing chloromethylbenzotriazole, trioctylphosphine and acetonitrile, heating under reflux to carry out quaternization reaction, and obtaining a crude trioctylphosphonium product functionalized with benzotriazole;

[0011] (2) washing the crude product of benzotriazole-functionalized trioctylphosphonium with an organic solvent for multiple times to obtain benzotriazole-functionalized trioctylphosphonium;

[0012] (3) Benzotriazole-functionalized trioctylphosphonium, docusate sodium and acetonitrile are mixed and subjected to an ion exchange reaction to obtain a benzotriazole-functionalized quaternary phosphonium salt ionic liquid, i.e., an oil-soluble ionic liquid.

[0013] Optionally, the molar ratio of chloromethylbenzotriazole to trioctylphosphine is 1:1-1.3.

[0014] Optionally, the quaternization reaction conditions are: heating under reflux at 80-85° C. for 24 h.

[0015] Optionally, the organic solvent used to wash the crude product of trioctylphosphonium functionalized with benzotriazole is petroleum ether or n-hexane.

[0016] Optionally, the ion exchange reaction is carried out under reflux at 80-90° C. for 24-48 hours.

[0017] Optionally, the molar ratio of benzotriazole-functionalized trioctylphosphonium to docusate sodium is 1:1-1.2.

[0018] Optionally, the ion exchange reaction further comprises:

[0019] After the ion exchange reaction, a crude oil-soluble ionic liquid is obtained. The crude oil-soluble ionic liquid is subjected to reduced pressure distillation, and the obtained heavy phase is dissolved in dichloromethane and washed with water multiple times. The layers are separated, and the obtained organic phase is dried to obtain a benzotriazole-functionalized quaternary phosphonium salt ionic liquid.

[0020] On the other hand, the present application provides an application of an oil-soluble ionic liquid with anti-corrosion and friction-reducing properties, wherein the oil-soluble ionic liquid is the above-mentioned oil-soluble ionic liquid, or the oil-soluble ionic liquid prepared using the above-mentioned preparation method, and the oil-soluble ionic liquid is used as a lubricating material.

[0021] The present application provides an oil-soluble ionic liquid with anti-corrosion and friction-reducing properties, and its preparation method and application, which realizes the preparation of the oil-soluble ionic liquid. The ionic liquid not only has excellent friction-reducing and anti-wear properties for steel / steel friction pairs, but also has good corrosion resistance. Compared with the existing technology, it has the following beneficial effects:

[0022] (1) The cation of the oil-soluble ionic liquid provided by the present application is a quaternary phosphonium cation with different alkyl chain lengths of a benzotriazole functional group, and the anion is sodium dioctyl sulfosuccinate. The introduction of the benzotriazole group can not only improve the stability of the ionic liquid, but also help the ionic liquid to form a stable lubricating film on the surface of the friction pair, which is conducive to improving the load-bearing performance of the ionic liquid. At the same time, the quaternary phosphonium salt ionic liquid is functionalized by benzotriazole, and the π electrons in the benzotriazole and the empty d orbitals on the iron surface can form a coordinated π-d conjugated effect adsorbed on the substrate surface to form a protective film, and the benzotriazole ring and long carbon chain structure unique to the ionic liquid can effectively isolate the corrosive environment, thereby preventing the corrosion of iron. By adopting quaternary phosphonium cations with different alkyl chain lengths, the ionic liquid has good oil solubility, which helps the ionic liquid to be fully dissolved in the base oil, further improving the friction and anti-wear performance of the ionic liquid. Therefore, the present application functionalizes the quaternary phosphonium salt ionic liquid by benzotriazole, so that the ionic liquid has excellent tribological properties and can further improve the anti-corrosion performance of the ionic liquid.

[0023] (2) The oil-soluble ionic liquid is used as a lubricating additive for the base oil PAO10 and is applied to the lubrication of steel / steel friction pairs. The experimental results show that the oil-soluble ionic liquid has good solubility in the base oil PAO10, and at the same time has not only excellent friction reduction and anti-wear properties on the steel / steel friction pair interface, but also has a good corrosion inhibition effect on the friction pair interface.

[0024] (3) The oil-soluble ionic liquid provided in this application does not contain halogen, does not corrode the surface of the metal friction pair, is environmentally friendly, and has good environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0026] Figure 1 Thermal decomposition temperature diagram of the ionic liquid lubricating composition provided in Examples 4 to 6 of the present application;

[0027] Figure 2 This is the Tafel plot of the ionic liquid lubricating composition provided in Example 6 of the present application. DETAILED DESCRIPTION

[0028] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application are clearly and completely described below. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts also fall within the scope of protection of this application.

[0029] The present application provides an oil-soluble ionic liquid with anti-corrosion and friction-reducing properties. The oil-soluble ionic liquid has the following general formula:

[0030]

[0031] Wherein R, R1 are independently selected from C1-C 18 of alkyl.

[0032] Specifically, quaternary phosphonium salt ionic liquid is a novel lubricant with extremely low volatility, good thermal stability and good viscosity-temperature properties. The cation of the oil-soluble ionic liquid provided in the present application is a quaternary phosphonium cation with different alkyl chain lengths of a benzotriazole functional group, and an anion is sodium dioctyl sulfosuccinate, and the introduction of a benzotriazole group can not only improve the stability of the ionic liquid, but also contribute to the ionic liquid forming a stable lubricating film on the friction pair surface, which is conducive to improving the load-bearing performance of the ionic liquid. Simultaneously, the quaternary phosphonium salt ionic liquid is functionalized by benzotriazole, and the π electrons in benzotriazole and the empty d orbitals of the iron surface can form a coordinated π-d conjugated effect adsorbed on the substrate surface to form a protective film, and the benzotriazole ring and long carbon chain structure unique to the ionic liquid can effectively isolate the corrosive environment, thereby preventing the corrosion of iron. By adopting different alkyl chain length quaternary phosphonium cations, the ionic liquid is made to have good oil solubility, which contributes to the ionic liquid being fully dissolved in the base oil, further improving the friction-reducing and anti-wear properties of the ionic liquid. Therefore, this application functionalizes a quaternary phosphonium salt ionic liquid with benzotriazole, resulting in an ionic liquid with excellent tribological properties while also further enhancing its anti-corrosion properties. Furthermore, the ionic liquid is halogen-free, non-corrosive to metal friction surfaces, and environmentally friendly, offering significant environmental benefits.

[0033] Optionally, R and R1 are independently selected from any one of methyl, ethyl, propyl, butyl, isobutyl, pentyl, isopentyl, octyl, isooctyl, decyl, isodecyl, dodecyl, tetradecyl, hexadecyl and octadecyl.

[0034] Specifically, ionic liquids synthesized with different alkyl chain lengths can be dissolved in different base oils, which helps to maintain the uniformity of the ionic liquid and base oil mixed system, and further helps to form a uniform and stable boundary lubrication film on the surface of the friction pair during the friction process, which is beneficial to better reduce friction, anti-wear and corrosion at the interface.

[0035] The present application provides a method for preparing an oil-soluble ionic liquid having anti-corrosion and friction-reducing properties, which is used to prepare the above-mentioned oil-soluble ionic liquid. The preparation method comprises the following steps:

[0036] (1) mixing chloromethylbenzotriazole, trioctylphosphine and acetonitrile, heating under reflux to carry out quaternization reaction, and obtaining a crude trioctylphosphonium product functionalized with benzotriazole;

[0037] (2) washing the crude product of benzotriazole-functionalized trioctylphosphonium with an organic solvent for multiple times to obtain benzotriazole-functionalized trioctylphosphonium;

[0038] (3) Benzotriazole-functionalized trioctylphosphonium, docusate sodium and acetonitrile are mixed and subjected to an ion exchange reaction to obtain a benzotriazole-functionalized quaternary phosphonium salt ionic liquid, i.e., an oil-soluble ionic liquid.

[0039] Specifically, the preparation reaction equation of the oil-soluble ionic liquid of the present application is as follows:

[0040]

[0041] In acetonitrile, chloromethylbenzotriazole and trioctylphosphine were mixed and subjected to a quaternization reaction. After the reaction was completed and cooled to room temperature, a crude benzotriazole-functionalized trioctylphosphonium product was obtained. The product was then washed multiple times with an organic solvent to remove any unreacted starting materials, resulting in the benzotriazole-functionalized trioctylphosphonium, designated BTAP888Cl. The benzotriazole-functionalized trioctylphosphonium, sodium docusate, and acetonitrile were mixed and subjected to an ion exchange reaction to obtain an oil-soluble benzotriazole-functionalized quaternary phosphonium salt ionic liquid (BTAP888-DOSS), whose cations consisted of quaternary phosphonium cations of varying alkyl chain lengths bearing the benzotriazole functional group and whose anion consisted of sodium dioctyl sulfosuccinate. The introduction of the benzotriazole group not only improved the stability of the ionic liquid but also helped the ionic liquid form a stable lubricating film on the friction pair surface, thereby enhancing the load-bearing performance of the ionic liquid. The π electrons in benzotriazole form a coordinated π-d conjugated interaction with the empty d orbitals on the iron surface, adsorbing onto the substrate to form a protective film. The benzotriazole ring and long carbon chain structure unique to ionic liquids effectively isolate the corrosive environment, thereby preventing corrosion of the iron. By using quaternary phosphonium cations with different alkyl chain lengths, the ionic liquid has improved oil solubility, which helps to maintain the uniformity of the ionic liquid and base oil mixture, and has a good anti-friction, anti-wear and corrosion inhibition effect at the interface.

[0042] Through the above scheme, the present application realizes the preparation of an oil-soluble ionic liquid with anti-corrosion and friction-reducing properties. The cation of the oil-soluble ionic liquid is a quaternary phosphonium cation of different alkyl chain lengths with a benzotriazole functional group, and the anion is sodium dioctyl sulfosuccinate. By mixing chloromethylbenzotriazole and trioctylphosphine, a quaternary phosphonium reaction is performed to obtain trioctylphosphonium functionalized with benzotriazole. The trioctylphosphonium functionalized with benzotriazole is then subjected to an ion exchange reaction with sodium docusate to obtain the oil-soluble ionic liquid. The introduction of the benzotriazole group not only improves the stability of the ionic liquid, but also helps the ionic liquid form a stable lubricating film on the surface of the friction pair, which is beneficial to improving the load-bearing performance of the ionic liquid. The benzotriazole ring and long carbon chain structure unique to the ionic liquid can effectively isolate the corrosive environment, thereby preventing the corrosion of iron. By using quaternary phosphonium cations with different alkyl chain lengths, the ionic liquid has better oil solubility, which helps the ionic liquid to fully dissolve in the base oil and further improves the friction reduction and anti-wear performance of the ionic liquid. This ionic liquid not only has excellent friction reduction and anti-wear performance for steel / steel friction pairs, but also has good anti-corrosion performance.

[0043] Optionally, the molar ratio of chloromethylbenzotriazole to trioctylphosphine is 1:1-1.3.

[0044] Optionally, the quaternization reaction conditions are: heating under reflux at 80-85° C. for 24 h.

[0045] Specifically, a suitable molar ratio of chloromethylbenzotriazole to trioctylphosphine can ensure that the quaternization reaction proceeds sufficiently. The temperature of the quaternization reaction is preferably 85°C.

[0046] In the quaternization reaction, there is no particular limitation on the amount of the reaction solvent acetonitrile. Furthermore, the ratio of chloromethylbenzotriazole to acetonitrile is preferably 1 mol: (150-200) mL.

[0047] Optionally, the organic solvent used to wash the crude product of trioctylphosphonium functionalized with benzotriazole is petroleum ether or n-hexane.

[0048] The amount of the organic solvent used in the washing process is not particularly limited. Specifically, the weight ratio of the crude benzotriazole-functionalized trioctylphosphonium product to the organic solvent is 1:3-5, and the organic solvent is washed three times on average.

[0049] Optionally, the ion exchange reaction is carried out under reflux at 80-90° C. for 24-48 hours.

[0050] Optionally, the molar ratio of benzotriazole-functionalized trioctylphosphonium to docusate sodium is 1:1-1.2.

[0051] Specifically, the molar ratio of benzotriazole-functionalized trioctylphosphonium to docusate sodium is preferably 1:1.2, and the temperature of the ion exchange reaction is preferably 85°C.

[0052] In the ion exchange reaction, there is no particular limitation on the amount of the reaction solvent acetonitrile. Furthermore, the ratio of benzotriazole-functionalized trioctylphosphonium to acetonitrile is preferably 1 mol: (150-180) mL.

[0053] Optionally, the ion exchange reaction further comprises:

[0054] After the ion exchange reaction, a crude oil-soluble ionic liquid is obtained. The crude oil-soluble ionic liquid is subjected to reduced pressure distillation, and the obtained heavy phase is dissolved in dichloromethane and washed with water multiple times. The layers are separated, and the obtained organic phase is dried to obtain a benzotriazole-functionalized quaternary phosphonium salt ionic liquid.

[0055] Specifically, the crude oil-soluble ionic liquid also contains impurities such as reaction solvent and unreacted raw materials, which need to be purified. First, the acetonitrile in the crude oil-soluble ionic liquid is removed by vacuum distillation, and the heavy phase obtained after vacuum distillation is dissolved in dichloromethane and washed with water several times, extracted and delaminated, the oil-soluble ionic liquid is dissolved in dichloromethane, and the impurities are dissolved in the aqueous phase. Wherein, the weight ratio of the heavy phase obtained after vacuum distillation to dichloromethane is 1:1.5-3, the weight ratio of the heavy phase to water is 1:2.5-3.5, and the washing water is evenly divided into three washings.

[0056] The organic phase is dried over anhydrous sodium sulfate for 10-24 hours to remove moisture. The dried organic phase is then filtered to remove the anhydrous sodium sulfate. Finally, the dichloromethane is again removed by vacuum distillation to obtain an oil-soluble ionic liquid, namely, a benzotriazole-functionalized quaternary phosphonium salt ionic liquid. The amount of anhydrous sodium sulfate used is 10-15 g per 100 mL of organic phase.

[0057] The above-mentioned process of removing the organic solvent by vacuum distillation is a commonly used and mature impurity removal method in the field. Those skilled in the art are capable of adjusting the operating parameters in the vacuum distillation according to the actual solvent to be distilled, and will not be described in detail here.

[0058] The present application provides an application of an oil-soluble ionic liquid with anti-corrosion and friction-reducing properties. The oil-soluble ionic liquid is the above-mentioned oil-soluble ionic liquid, or an oil-soluble ionic liquid prepared using the above-mentioned preparation method, and the oil-soluble ionic liquid is used as a lubricating material.

[0059] The oil-soluble ionic liquid provided in the present application is used as a lubricant additive for steel / steel friction pairs, and has a good friction-reducing, anti-wear and corrosion-inhibiting effect on the interface of the steel / steel friction pair.

[0060] The following are embodiments of the present invention and effect test examples, which further describe the technical solutions and technical effects of the present invention, but the scope of protection of the present invention is not limited to these embodiments. Any changes or equivalent substitutions that do not deviate from the concept of the present invention are within the scope of protection of the present invention. In addition, those who do not specify specific technical operation steps or conditions in the embodiments are all carried out according to the technology or conditions described in the general literature in this area or according to the product specifications. Those whose reagents or instruments are not specified by the manufacturer are all conventional products that can be obtained commercially.

[0061] Example 1

[0062] An oil-soluble ionic liquid with anti-corrosion and friction-reducing properties and a preparation method thereof, comprising the following steps:

[0063] (1) mixing chloromethylbenzotriazole, trioctylphosphine and acetonitrile, heating under reflux to carry out quaternization reaction, and obtaining a crude trioctylphosphonium product functionalized with benzotriazole;

[0064] The molar ratio of chloromethylbenzotriazole to trioctylphosphine is 1:1, the amount ratio of chloromethylbenzotriazole to acetonitrile is 1 mol:150 mL, and the conditions of the quaternization reaction are: heating under reflux at 80° C. for 24 h.

[0065] (2) The crude product of benzotriazole-functionalized trioctylphosphonium was washed with petroleum ether several times to obtain benzotriazole-functionalized trioctylphosphonium, named BTAP888Cl-1;

[0066] The weight ratio of the crude benzotriazole-functionalized trioctylphosphonium product to the organic solvent is 1:3.

[0067] (3) Mixing benzotriazole-functionalized trioctylphosphonium, sodium docusate, and acetonitrile and subjecting the mixture to an ion exchange reaction to obtain a crude benzotriazole-functionalized quaternary phosphonium salt ionic liquid. The molar ratio of benzotriazole-functionalized trioctylphosphonium to sodium docusate is preferably 1:1, and the amount ratio of benzotriazole-functionalized trioctylphosphonium to acetonitrile is preferably 1 mol:150 mL. The ion exchange reaction is carried out under heating reflux at 80° C. for 24 hours.

[0068] First, acetonitrile was removed from the crude oil-soluble ionic liquid by vacuum distillation. The resulting heavy phase was dissolved in dichloromethane and washed multiple times with water. The layers were separated by extraction, leaving the oil-soluble ionic liquid dissolved in the dichloromethane and the impurities dissolved in the aqueous phase. The organic phase was dried over anhydrous sodium sulfate for 24 hours to remove moisture. The dried organic phase was then filtered to remove the anhydrous sodium sulfate. Finally, vacuum distillation was performed again to remove the dichloromethane, yielding the oil-soluble ionic liquid, a benzotriazole-functionalized quaternary phosphonium salt ionic liquid named BTAP888-DOSS-1.

[0069] The weight ratio of the heavy phase obtained after vacuum distillation to dichloromethane was 1:1.5, and the weight ratio of the heavy phase to water was 1:2.5. The washing water was evenly divided into three times. The amount of anhydrous sodium sulfate used was: 10g of anhydrous sodium sulfate per 100mL of organic phase.

[0070] The molecular structure of the BTAP888-DOSS sample is as follows:

[0071]

[0072] Example 2

[0073] An oil-soluble ionic liquid with anti-corrosion and friction-reducing properties and a preparation method thereof, comprising the following steps:

[0074] (1) mixing chloromethylbenzotriazole, trioctylphosphine and acetonitrile, heating under reflux to carry out quaternization reaction, and obtaining a crude trioctylphosphonium product functionalized with benzotriazole;

[0075] The molar ratio of chloromethylbenzotriazole to trioctylphosphine is 1:1.2, the amount ratio of chloromethylbenzotriazole to acetonitrile is 1 mol:170 mL, and the conditions of the quaternization reaction are: heating under reflux at 85° C. for 24 hours.

[0076] (2) The crude product of benzotriazole-functionalized trioctylphosphonium was washed with petroleum ether several times to obtain benzotriazole-functionalized trioctylphosphonium, named BTAP888Cl-2;

[0077] The weight ratio of the crude benzotriazole-functionalized trioctylphosphonium product to the organic solvent is 1:4.

[0078] (3) Mixing benzotriazole-functionalized trioctylphosphonium, sodium docusate, and acetonitrile and subjecting the mixture to an ion exchange reaction to obtain a crude benzotriazole-functionalized quaternary phosphonium salt ionic liquid. The molar ratio of benzotriazole-functionalized trioctylphosphonium to sodium docusate is preferably 1:1.2, and the amount ratio of benzotriazole-functionalized trioctylphosphonium to acetonitrile is preferably 1 mol:165 mL. The ion exchange reaction is carried out under heating reflux at 85°C for 48 hours.

[0079] First, acetonitrile was removed from the crude oil-soluble ionic liquid by vacuum distillation. The resulting heavy phase was dissolved in dichloromethane and washed multiple times with water. The layers were separated by extraction, leaving the oil-soluble ionic liquid dissolved in the dichloromethane and the impurities dissolved in the aqueous phase. The organic phase was dried over anhydrous sodium sulfate for 24 hours to remove moisture. The dried organic phase was then filtered to remove the anhydrous sodium sulfate. Finally, vacuum distillation was performed again to remove the dichloromethane, yielding the oil-soluble ionic liquid, a benzotriazole-functionalized quaternary phosphonium salt ionic liquid named BTAP888-DOSS-2.

[0080] The weight ratio of the heavy phase obtained after vacuum distillation to dichloromethane was 1:2.5, and the weight ratio of the heavy phase to water was 1:3. The washing water was evenly divided into three times. The amount of anhydrous sodium sulfate used was: 12g of anhydrous sodium sulfate per 100mL of organic phase.

[0081] Example 3

[0082] An oil-soluble ionic liquid with anti-corrosion and friction-reducing properties and a preparation method thereof, comprising the following steps:

[0083] (1) mixing chloromethylbenzotriazole, trioctylphosphine and acetonitrile, heating under reflux to carry out quaternization reaction, and obtaining a crude trioctylphosphonium product functionalized with benzotriazole;

[0084] The molar ratio of chloromethylbenzotriazole to trioctylphosphine is 1:1.3, the amount ratio of chloromethylbenzotriazole to acetonitrile is 1 mol:200 mL, and the conditions of the quaternization reaction are: heating under reflux at 85° C. for 24 hours.

[0085] (2) The crude product of benzotriazole-functionalized trioctylphosphonium was washed with petroleum ether several times to obtain benzotriazole-functionalized trioctylphosphonium, named BTAP888Cl-3;

[0086] The weight ratio of the crude benzotriazole-functionalized trioctylphosphonium product to the organic solvent is 1:5.

[0087] (3) Mixing benzotriazole-functionalized trioctylphosphonium, sodium docusate, and acetonitrile and subjecting the mixture to an ion exchange reaction to obtain a crude benzotriazole-functionalized quaternary phosphonium salt ionic liquid. The molar ratio of benzotriazole-functionalized trioctylphosphonium to sodium docusate is preferably 1:1.2, and the amount ratio of benzotriazole-functionalized trioctylphosphonium to acetonitrile is preferably 1 mol:180 mL. The ion exchange reaction is carried out under heating reflux at 85° C. for 48 hours.

[0088] First, acetonitrile was removed from the crude oil-soluble ionic liquid by vacuum distillation. The resulting heavy phase was dissolved in dichloromethane and washed multiple times with water. The layers were separated by extraction, leaving the oil-soluble ionic liquid dissolved in the dichloromethane and the impurities dissolved in the aqueous phase. The organic phase was dried over anhydrous sodium sulfate for 24 hours to remove moisture. The dried organic phase was then filtered to remove the anhydrous sodium sulfate. Finally, vacuum distillation was repeated to remove the dichloromethane, yielding the oil-soluble ionic liquid, a benzotriazole-functionalized quaternary phosphonium salt ionic liquid named BTAP888-DOSS-3.

[0089] The weight ratio of the heavy phase obtained after vacuum distillation to dichloromethane was 1:3, and the weight ratio of the heavy phase to water was 1:3.5. The washing water was evenly divided into three times. The amount of anhydrous sodium sulfate used was: 15g of anhydrous sodium sulfate per 100mL of organic phase.

[0090] Experimental Example 1

[0091] Structural Characterization of Oil-Soluble Ionic Liquids

[0092] The oil-soluble ionic liquid obtained by the technical solutions provided in Examples 1 to 3 was subjected to nuclear magnetic resonance 1 H NMR, 13 C NMR, 31 The results of P NMR and high-resolution mass spectrometry HRMS characterization showed that Examples 1-3 all achieved the preparation of oil-soluble ionic liquids, and the characterization data of Example 2 are as follows:

[0093] 1H NMR (400MHz, CDCl3) δ: 8.31 (d, J = 4.0Hz, 1H), 8.01 (d, J = 4.0Hz, 1H), 7.63 (t, J = 8.0Hz, 1H), 7.41 (t, J = 8.0Hz, 1H), 6.06 (s, 2H), 4.2 0(dd,J1=12.0Hz,J2=4.0Hz,1H),4.03-3.88(m,4H),3.32-3.13(m,2H),2.47-2.40(m,6H),1.72-1.17(m,54H),0.87-0.77(m,21H). 13 C NMR(100MHz, CDCl3)δ:171.65,169.28,145.40,134.18,134.16,129.68,125.27,119.70,11 1.27,67.88,67.19,62.07,39.58,39.06,38.78,38.76,38.64,38.57,34.30,31.72,30.84,3 0.69,30.41,30.37,30.11,29.16,29.13,29.01,28.98,28.94,28.91,28.85,23.75,23.48,23.05,22.71,22.64,21.73,21.69,18.79,18.36,14.14,14.12,11.04,11.00,10.87,10.83. 31 P NMR (162MHz,CDCl3)δ:35.10(s).Theoretical calculation value of cation:502.4285,actual measured value of cation:502.4263[C 31 H 57 N3P] + , anion theoretical calculated value: 421.2265, anion actual measured value: 421.2275 [C 20 H 37 O7S] - .

[0094] Experimental Example 2

[0095] Solubility test of oil-soluble ionic liquids

[0096] The solubility of the oil-soluble ionic liquid BTAP888-DOSS-2 obtained by the technical solution provided in Example 2 in the base oil PAO10 was studied.

[0097] The test method is as follows: a certain mass of PAO10 and the oil-soluble ionic liquid BTAP888-DOSS-2 synthesized in Example 2 are weighed, heated to 70°C, stirred and mixed for 30 minutes, and the dissolution of the oil-soluble ionic liquid with different mass fractions in PAO10 is observed. The results are shown in Table 1.

[0098] Table 1

[0099] BTAP888-DOSS-2 quality score dissolved state 0.1wt.% Dissolved, transparent 0.3wt.% Dissolved, transparent 0.5wt.% Dissolved, transparent 1.0wt.% Dissolved, transparent 5.0wt.% Dissolved, transparent

[0100] As shown in Table 1, the oil-soluble ionic liquid BTAP888-DOSS-2 provided herein has excellent solubility in the base oil PAO10. The use of long-chain alkyl quaternary phosphonium cations imparts good oil solubility to the ionic liquid, contributing to the uniformity of the ionic liquid / base oil mixture and providing excellent friction reduction, anti-wear, and corrosion inhibition at the interface.

[0101] Example 4

[0102] Preparation of ionic liquid lubricating composition 1: 99.9 g of PAO10 and 0.1 g of the oil-soluble ionic liquid BTAP888-DOSS-2 synthesized in Example 2 were weighed, heated to 70° C., and stirred for 30 min to obtain an ionic liquid lubricating composition 1 with a mass fraction of 0.1%.

[0103] Example 5

[0104] Preparation of ionic liquid lubricating composition 2: 99.7 g of PAO10 and 0.3 g of the oil-soluble ionic liquid BTAP888-DOSS-2 synthesized in Example 2 were weighed, heated to 70° C., and stirred for 30 min to obtain an ionic liquid lubricating composition 2 with a mass fraction of 0.3%.

[0105] Example 6

[0106] Preparation of ionic liquid lubricating composition 3: 99.5 g of PAO10 and 0.5 g of the oil-soluble ionic liquid BTAP888-DOSS-2 synthesized in Example 2 were weighed, heated to 70° C., and stirred for 30 min to obtain an ionic liquid lubricating composition 3 with a mass fraction of 0.5%.

[0107] Experimental Example 3

[0108] Thermal stability test of ionic liquid lubricating composition:

[0109] Test method: With base oil PAO10 as a control sample, the thermal stability of the ionic liquid lubricating compositions obtained in Examples 4 to 6 and the base oil PAO10 were analyzed using a STA449-F3 (NETZSCH, TGA-DSC) synchronous thermal analyzer.

[0110] The test conditions are: nitrogen atmosphere, heating rate 10℃ / min, heating range: room temperature to 600℃. The thermal stability of the ionic liquid lubricating composition is as follows: Figure 1 shown.

[0111] Depend on Figure 1 It is obvious that the decomposition temperature of the ionic liquid lubricating composition is increased compared with the base oil PAO10, and the amount of ionic liquid provided by the present application added in Examples 4 to 6 is very small, and the mass fraction of the ionic liquid is only between 0.1% and 0.5%. This shows that the addition of a small amount of ionic liquid of the present application can greatly improve the thermal stability of the base oil PAO10, which helps the ionic liquid lubricating composition to form a stable and continuous boundary lubricating film on the friction pair during the lubrication process, so that the ionic liquid lubricating composition can be suitable for lubrication in different temperature environments.

[0112] Experimental Example 4

[0113] Dynamic viscosity and viscosity index test of ionic liquid lubricating composition:

[0114] Test method: The kinematic viscosity and viscosity index of the ionic liquid lubricating composition and the base oil PAO10 were measured using an SVM3000 petroleum product kinematic viscometer produced by Anton Paar, Austria. The results are shown in Table 2.

[0115] Table 2

[0116]

[0117] As can be seen from Table 2, the viscosity index of the ionic liquid lubricating compositions in Examples 4 to 6 is improved compared to that of the base oil PAO10, indicating that the ionic liquid of the present application, as a lubricating additive for the base oil PAO10, can maintain good fluidity at low temperatures and still have sufficient viscosity at high temperatures to form an effective oil film on the surface of the friction pair during the friction process, ensuring sufficient lubrication between the interfaces.

[0118] Experimental Example 4

[0119] Tribological performance test of ionic liquid lubricating composition:

[0120] Test method: The friction and wear performance of the ionic liquid lubricating composition was evaluated using an SRV-IV fretting friction tester produced by Optimol, Germany, and compared with the base oil PAO10.

[0121] The test conditions were: ball-on-disk contact, temperature 25°C, frequency 50 Hz, amplitude 1 mm, and test duration 30 minutes. The upper test ball was a 10 mm Ø AISI 52100 steel ball with a hardness of 59-61 HRC. The lower test specimen in the steel / steel friction pair was a 24 mm Ø, 7.9 mm thick AISI 52100 steel block with a hardness of 59-61 HRC. The test load was 200 N. The wear volume of the lower test specimen was measured using a laser confocal microscope. Each experiment was repeated at least three times, and the average values ​​were taken. The average friction coefficient and average wear volume of the ionic liquid lubricant composition at 25°C are shown in Table 3.

[0122] Table 3

[0123] Average friction coefficient <![CDATA[Average wear volume / 10 -3 mm 3 <!-- 9 -->]]> PAO10 0.22589 2.70211 Example 4 0.17509 1.95948 Example 5 0.11340 0.55105 Example 6 0.11285 0.47344

[0124] Observation table 3 shows that, compared to base oil PAO10, the average friction coefficient and the average wear volume of ionic liquid lubricating composition are significantly decreased, illustrating that the quaternary phosphonium salt ionic liquid of the benzotriazole functionalization provided by the application has good friction reduction and anti-wear performance, the cation of the oil-soluble ionic liquid provided by the application is the different alkyl chain length quaternary phosphonium cation with benzotriazole functional group, anion is sodium diisooctyl sulfosuccinate, the introduction of benzotriazole group, not only can improve the stability of ionic liquid, while the π electrons in benzotriazole and the empty d orbital of iron surface can form coordination π-d conjugated effect adsorbed on matrix surface to form protective film, contribute to ionic liquid to form stable lubricating film on friction pair surface, conducive to improving the load-bearing performance of ionic liquid. And ionic liquid base oil PAO10 and have good oil solubility, contribute to ionic liquid fully dissolved in base oil, further improve the friction reduction and anti-wear performance of ionic liquid.

[0125] Experimental Example 5

[0126] Corrosion inhibition performance test of ionic liquid lubricating composition:

[0127] Test method: The corrosion inhibition performance of the ionic liquid lubricant composition obtained in Example 6 was tested using an electrochemical test method. A 1cm×1cm platinum electrode was used as the counter electrode; an iron disk electrode with a diameter of 0.8cm (purity>99.99%) wrapped in epoxy resin was used, leaving an exposed area with a diameter of 0.5cm as the working electrode; saturated calomel was used as the reference electrode to form a three-electrode system. The three-electrode system was immersed in a solution of ethanol:H2O=2:1 (mass ratio). In order to obtain a stable open circuit potential (OCP), it was recorded for 60 minutes. The parameters of the potential dynamic polarization (Tafel) are E=Eocp±200mV, and the scanning rate is 0.333mV / s. The results are as follows Figure 2At the same time, the open circuit potential and corrosion current density of the ionic liquid lubricating composition were obtained, as shown in Table 4.

[0128] Table 4

[0129] Open circuit potential / V Corrosion current density / log(i / A) PAO10 -0.3048 -8.23 Example 6 -0.2144 -8.65

[0130] Since the ionic liquid lubricating composition cannot be dissolved in pure water, an ethanol aqueous solution (ethanol: H2O=2:1 (mass ratio)) is used as a solvent and a corrosive medium. Figure 2 The anti-corrosion performance of the ionic liquid lubricating composition on iron in ethanol aqueous solution is shown. Figure 2 The "0.5%" in the table is the mass concentration of the ionic liquid lubricating composition in the ethanol aqueous solution. Figure 2 It can be seen that the corrosion current density of the ionic liquid lubricating composition is generally smaller than that of the ethanol-water solution. Generally speaking, the greater the corrosion potential, the lower the corrosion tendency, and the greater the corrosion current density, the greater the degree of corrosion. In the experiment, the corrosion potential of the ionic liquid lubricating composition in the ethanol-water solution shifted positively, and the corrosion current density was significantly reduced, showing good corrosion resistance. This shows that the ionic liquid lubricating composition effectively improves the corrosion resistance of iron. The enhancement of corrosion resistance is attributed to the ionic liquid lubricating composition forming a protective film on the substrate surface through the π electrons in the benzotriazole and the empty d orbitals on the iron surface. The benzotriazole ring and long carbon chain structure unique to the ionic liquid lubricating composition can effectively isolate the corrosive environment, thereby preventing the corrosion of iron.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An oil-soluble ionic liquid with anti-corrosion and friction-reducing properties, characterized in that: The oil-soluble ionic liquid has the following general formula: Wherein R, R1 are independently selected from C1-C 18 of alkyl.

2. The oil-soluble ionic liquid with anti-corrosion and friction-reducing properties according to claim 1, characterized in that: The R and R1 are independently selected from any one of methyl, ethyl, propyl, butyl, isobutyl, pentyl, isopentyl, octyl, isooctyl, decyl, isodecyl, dodecyl, tetradecyl, hexadecyl and octadecyl.

3. A method for preparing an oil-soluble ionic liquid with anti-corrosion and friction-reducing properties, for preparing the oil-soluble ionic liquid according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: (1) mixing chloromethylbenzotriazole, trioctylphosphine and acetonitrile, heating under reflux to carry out quaternization reaction, and obtaining a crude trioctylphosphonium product functionalized with benzotriazole; (2) washing the crude benzotriazole-functionalized trioctylphosphonium product with an organic solvent multiple times to obtain benzotriazole-functionalized trioctylphosphonium; (3) The benzotriazole-functionalized trioctylphosphonium, docusate sodium and acetonitrile are mixed and subjected to an ion exchange reaction to obtain a benzotriazole-functionalized quaternary phosphonium salt ionic liquid, namely the oil-soluble ionic liquid.

4. The method for preparing an oil-soluble ionic liquid having anti-corrosion and friction-reducing properties according to claim 3, wherein: The molar ratio of the chloromethylbenzotriazole to the trioctylphosphine is 1:1-1.

3.

5. The method for preparing an oil-soluble ionic liquid having anti-corrosion and friction-reducing properties according to claim 3, wherein: The conditions of the quaternization reaction are: heating under reflux at 80-85° C. for 24 hours.

6. The method for preparing an oil-soluble ionic liquid having anti-corrosion and friction-reducing properties according to claim 3, wherein: The organic solvent used for washing the crude benzotriazole-functionalized trioctylphosphonium product is petroleum ether or n-hexane.

7. The method for preparing an oil-soluble ionic liquid having anti-corrosion and friction-reducing properties according to claim 3, wherein: The ion exchange reaction is carried out under reflux at 80-90° C. for 24-48 hours.

8. The method for preparing an oil-soluble ionic liquid having anti-corrosion and friction-reducing properties according to claim 3, wherein: The molar ratio of the benzotriazole-functionalized trioctylphosphonium to the docusate sodium is 1:1-1.

2.

9. The method for preparing an oil-soluble ionic liquid having anti-corrosion and friction-reducing properties according to claim 3, wherein: The ion exchange reaction further comprises: After the ion exchange reaction is completed, the crude oil-soluble ionic liquid is obtained, the crude oil-soluble ionic liquid is subjected to reduced pressure distillation, the obtained heavy phase is dissolved in dichloromethane, and washed with water multiple times, separated into layers, and the obtained organic phase is dried to obtain the benzotriazole-functionalized quaternary phosphonium salt ionic liquid.

10. An application of an oil-soluble ionic liquid with anti-corrosion and friction-reducing properties, characterized in that: The oil-soluble ionic liquid is the oil-soluble ionic liquid described in claim 1 or 2, or an oil-soluble ionic liquid prepared by the preparation method described in any one of claims 3 to 9, and the oil-soluble ionic liquid is used as a lubricating material.

Images