Phosphate ammonium salt ionic liquid, preparation method and application of phosphate ammonium salt ionic liquid in lubricating composition

Abstract

The invention provides a phosphate ammonium salt ionic liquid, a preparation method and application of the phosphate ammonium salt ionic liquid in a lubricating composition, cations of the phosphate ammonium salt ionic liquid are ammonium salt cations with different alkyl chain lengths, anions of the phosphate ammonium salt ionic liquid are phosphate with different chain lengths, and the preparation method of the ionic liquid comprises the following steps: adding alkylamine and phosphate into a round-bottom flask; and heating for 2-24 hours, and cooling to obtain the phosphate ammonium salt ionic liquid. The phosphate ammonium salt ionic liquid is used as a lubricant additive to be applied to a lubricating composition, so that the antifriction performance, the antiwear performance and the anti-rust performance of base oil are remarkably improved.

Description

Technical Field

[0001] This application relates to the field of lubricating materials technology, and in particular to an ammonium phosphate salt ionic liquid, its preparation method, and its application in lubricating compositions. Background Technology

[0002] Lubricating additives are a core component of lubricating oils and the essence of modern high-end lubricating oils. Additives can significantly improve the physicochemical properties of lubricating oils, endowing them with new characteristics or enhancing their existing properties to meet higher technical demands. The overall performance of lubricating oils is largely determined by the development of additive technology. Therefore, the technological development, industrialization, and engineering applications of the additive industry, to a certain extent, determine the overall development level of lubricating oils and also influence the development speed and level of high-end and high-tech equipment.

[0003] The additives industry overseas is highly concentrated, currently dominated by four major additive companies: Lubrizol, Infineum, Chevron, and Afton. There are also smaller, specialized additive companies such as Chemie, BASF, Vanderbilt, and Evonik, which produce single additives. These companies possess globally leading R&D capabilities and hold over 90% of the global market share.

[0004] Among fatty acid phosphate ester rust and anti-wear agents, Jinshi Chemical's AW-6110 outperforms similar commercially available products and has achieved a leading position in the high-end lubricant market. Therefore, it is necessary to independently design the molecular structure of phosphate ester amine salts and improve the technology for producing high-quality additives. Through this application, a phosphate ester rust and anti-wear agent product with better overall performance can be developed. Summary of the Invention

[0005] This application provides an ammonium phosphate salt ionic liquid, its preparation method, and its application in lubricating compositions to solve the problems mentioned in the background art.

[0006] On one hand, this application provides an ammonium phosphate salt ionic liquid, wherein the cation of the ammonium phosphate salt ionic liquid is an ammonium salt cation with different alkyl chain lengths, and the anion is a phosphate ester with different chain lengths. The ammonium phosphate salt ionic liquid includes the general formula shown in Formula I:

[0007] Formula I In Formula I, R, R1, and R2 are each independently selected from C1-C18 alkyl groups.

[0008] Optionally, R, R1, and R2 are each independently selected from C1-C18 alkyl groups that are straight-chain, branched, or cyclic.

[0009] Optionally, R, R1 and R2 are each independently selected from any one of methyl, ethyl, propyl, butyl, isobutyl, pentyl, isopentyl, octyl, isooctyl, decyl, isodecyl, dodecyl, tetradecyl, hexadecyl and octadecyl.

[0010] On the other hand, this application provides a method for preparing an ammonium phosphate salt ionic liquid, which is used to prepare the above-mentioned ammonium phosphate salt ionic liquid. The preparation method includes the following steps: Alkylamine and phosphate ester were placed in a round-bottom flask and heated to 80-85℃ for 2-24 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain ammonium phosphate ion liquid.

[0011] Optionally, the molar ratio of alkylamine to phosphate ester is 1:1.

[0012] In another aspect, this application provides the application of an ammonium phosphate ionic liquid in a lubricating composition, wherein the ammonium phosphate ionic liquid is the aforementioned ammonium phosphate ionic liquid or an ammonium phosphate ionic liquid prepared by the aforementioned method, and the ammonium phosphate ionic liquid is used as a lubricant additive in the lubricating composition.

[0013] Optionally, the lubricating composition comprises the following components in weight percentages: 0.1-0.5% of a mixture of one or more ammonium phosphate ionic liquids and the balance base oil.

[0014] Optionally, the lubricating composition further includes: 0.03-0.1% molybdenum disulfide, 0.02-0.05% 4,4'-dihydroxydiphenyl sulfide, 0.01-0.03% ethoxybenzamide, and at least one additive selected from friction modifiers, dispersants, and pour point depressants.

[0015] Optionally, the base oil includes at least one of 150SN, PAO10, and base oil 5750.

[0016] Optionally, the preparation method of the lubricating composition includes: Weigh out 0.1-0.5% by mass of a mixture of one or more ammonium phosphate ionic liquids, 0.02-0.05% by mass of 4,4'-dihydroxydiphenyl sulfide, 0.03-0.1% by mass of molybdenum disulfide, 0.01-0.03% by mass of ethoxybenzamide, at least one additive selected from friction modifiers, dispersants, pour point depressants, and the balance base oil. Heat the mixture to 50-60°C and stir for 30-40 minutes while maintaining the temperature to obtain a lubricating composition.

[0017] The ammonium phosphate salt ionic liquid, its preparation method, and its application in lubricating compositions provided in this application realize the preparation of the ammonium phosphate salt ionic liquid and its application as a lubricant additive. Compared with the prior art, it has the following beneficial effects: (1) This application obtains an ammonium phosphate ionic liquid with cations consisting of ammonium salt cations with different alkyl chain lengths and anions consisting of phosphate esters with different chain lengths through simple molecular design. This type of ammonium phosphate ionic liquid has excellent high-temperature stability. The phosphate ester anions can form an adsorption film and / or a chemical reaction film on the metal surface, exhibiting excellent friction reduction and wear resistance for steel / steel friction pairs. At the same time, the formation of the protective film can isolate oxygen and other corrosive ions from direct contact with the friction pair. Therefore, the ammonium phosphate ionic liquid provided in this application also has good rust prevention properties. Moreover, this ionic liquid is environmentally friendly.

[0018] (2) The ammonium phosphate ionic liquid provided in this application, when used as a lubricant additive in lubricating compositions, significantly improves the friction-reducing, anti-wear, and anti-rust properties of the base oil. Furthermore, the phosphate ester anions form hydrogen bonds with metal oxides (such as Fe2O3) through P=O bonds, enhancing the strength of the adsorption film and thus significantly improving the lubrication performance of the base oil. During friction, the ammonium phosphate ionic liquid provided in this application decomposes the phosphate ester anions to generate hard, wear-resistant layers such as iron phosphate (FePO4) and polyphosphates, improving the anti-wear performance of the base oil. Moreover, the lone pair electrons of N in the ammonium salt cation can coordinate with the metal surface, enhancing the strength of the composite protective film and further improving the lubrication effect.

[0019] (3) This application utilizes 4,4'-dihydroxydiphenyl sulfide to form hydrogen bonds or dipole-dipole interactions with sulfur atoms on the surface of molybdenum disulfide under high temperature / high pressure friction. Furthermore, during friction, the π electrons of the benzene ring in 4,4'-dihydroxydiphenyl sulfide interact with the sulfur layer of molybdenum disulfide via π-sulfur interactions. This further enhances the stability and continuity of the lubricating film during friction, significantly improving the friction-reducing and anti-wear properties of the base oil. Simultaneously, the synergistic effect of 4,4'-dihydroxydiphenyl sulfide with the ammonium phosphate ionic liquid and molybdenum disulfide provides excellent rust prevention for the friction pair.

[0020] (4) Simultaneously adding ethoxybenzamide allows the amide and ether bonds in ethoxybenzamide to interact with the metal surface during friction, forming a solid compound film of a certain thickness. This film shifts under shear force, always filling the space between the friction pairs, preventing the metal surface from contacting corrosive media such as air and water, thus improving the rust-preventive performance of the lubricating composition. Furthermore, the phenolic hydroxyl groups in 4,4'-dihydroxydiphenyl sulfide can be adsorbed onto the metal surface via hydrogen bonds, forming a physical protective film. Simultaneously, the benzene rings in 4,4'-dihydroxydiphenyl sulfide and ethoxybenzamide enhance the mechanical strength of the protective film. The layered structure of molybdenum disulfide easily slips under shear force, synergistically forming a dense and stable lubricating film with the lubricating film formed by ethoxybenzamide and 4,4'-dihydroxydiphenyl sulfide. This lubricating film can isolate moisture, oxygen, and other corrosive media (such as SO2, Cl) during friction. - This avoids direct contact between corrosive media and the friction pair, thus providing excellent rust prevention and excellent friction reduction and wear resistance between the friction pairs.

[0021] (5) The ammonium phosphate salt ionic liquid provided in this application can also be applied in aerospace (such as high temperature gearbox lubrication), new energy vehicles and precision machinery. It can reduce friction and wear, improve the rust prevention performance of equipment parts, and extend the service life of equipment. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The 1H NMR spectrum of the ammonium phosphate salt ionic liquid provided in Example 1 of this application; Figure 2 The carbon NMR spectrum of the ammonium phosphate salt ionic liquid provided in Example 1 of this application; Figure 3 The NMR phosphorus spectrum of the ammonium phosphate salt ionic liquid provided in Example 1 of this application; Figure 4 The 1H NMR spectrum of the ammonium phosphate salt ionic liquid provided in Example 2 of this application; Figure 5 The carbon NMR spectrum of the ammonium phosphate salt ionic liquid provided in Example 2 of this application; Figure 6The NMR phosphorus spectrum of the ammonium phosphate salt ionic liquid provided in Example 2 of this application; Figure 7 The 1H NMR spectrum of the ammonium phosphate salt ionic liquid provided in Example 3 of this application; Figure 8 The carbon NMR spectrum of the ammonium phosphate salt ionic liquid provided in Example 3 of this application; Figure 9 The NMR phosphorus spectrum of the ammonium phosphate salt ionic liquid provided in Example 3 of this application; Figure 10 The 1H NMR spectrum of the ammonium phosphate salt ionic liquid provided in Example 4 of this application; Figure 11 The carbon NMR spectrum of the ammonium phosphate salt ionic liquid provided in Example 4 of this application; Figure 12 The NMR phosphorus spectrum of the ammonium phosphate salt ionic liquid provided in Example 4 of this application. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this application.

[0025] On one hand, this application provides an ammonium phosphate salt ionic liquid, wherein the cation of the ammonium phosphate salt ionic liquid is an ammonium salt cation with different alkyl chain lengths, and the anion is a phosphate ester with different chain lengths. The ammonium phosphate salt ionic liquid includes the general formula shown in Formula I:

[0026] Formula I In Formula I, R, R1, and R2 are each independently selected from C1-C18 alkyl groups.

[0027] This application, through simple molecular design, obtains an ammonium phosphate ionic liquid where the cations are ammonium salt cations with different alkyl chain lengths, and the anions are phosphate esters with different chain lengths. This type of ammonium phosphate ionic liquid exhibits a high decomposition temperature and excellent high-temperature stability. The phosphate ester anions in this type of ammonium phosphate ionic liquid can form an adsorption film and / or a chemical reaction film on the metal surface, thereby forming a PO-Fe protective film. This film provides excellent friction reduction and wear resistance for steel / steel friction pairs. Simultaneously, the formation of the protective film can isolate oxygen and other corrosive ions from direct contact with the friction pair. Therefore, the ammonium phosphate ionic liquid provided in this application also has good rust prevention properties. Furthermore, this ionic liquid has low volatility and is environmentally friendly.

[0028] Optionally, R, R1, and R2 are each independently selected from C1-C18 alkyl groups that are straight-chain, branched, or cyclic.

[0029] Optionally, R, R1 and R2 are each independently selected from any one of methyl, ethyl, propyl, butyl, isobutyl, pentyl, isopentyl, octyl, isooctyl, decyl, isodecyl, dodecyl, tetradecyl, hexadecyl and octadecyl.

[0030] On the other hand, this application provides a method for preparing an ammonium phosphate salt ionic liquid, which is used to prepare the above-mentioned ammonium phosphate salt ionic liquid. The preparation method includes the following steps: Alkylamine and phosphate ester were placed in a round-bottom flask and heated to 80-85℃ for 2-24 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain ammonium phosphate ion liquid.

[0031] Optionally, the molar ratio of alkylamine to phosphate ester is 1:1.

[0032] Specifically, alkylamines are mixed with phosphate esters and heated, and a direct neutralization reaction is carried out under heating to generate the ammonium salt ionic liquid of the phosphate ester. Furthermore, nitrogen gas is purged during the reaction to prevent moisture interference.

[0033] Those skilled in the art determine the specific structure of alkylamines and phosphate esters based on the general formula shown in Formula I above, according to actual working conditions, and no limitation is made here.

[0034] In another aspect, this application provides the application of an ammonium phosphate ionic liquid in a lubricating composition, wherein the ammonium phosphate ionic liquid is the aforementioned ammonium phosphate ionic liquid or an ammonium phosphate ionic liquid prepared by the aforementioned method, and the ammonium phosphate ionic liquid is used as a lubricant additive in the lubricating composition.

[0035] Optionally, the lubricating composition comprises the following components in weight percentages: 0.1-0.5% of one or more ammonium phosphate ionic liquids and the balance base oil.

[0036] Specifically, the ammonium phosphate salt ionic liquid provided in this application is used as a lubricant additive in lubricating compositions. Different alkylamines and phosphate esters are selected to synthesize one or more ammonium phosphate salt ionic liquids, and the ionic liquid is added to the base oil as a lubricating additive, which significantly improves the friction reduction, anti-wear, and rust prevention properties of the base oil.

[0037] Among them, P=O bond and PO - The strong polarity of ammonium phosphate causes it to preferentially adsorb onto metal surfaces (such as Fe and Al), forming an adsorption layer and / or generating a chemical reaction film during friction. Simultaneously, ammonium cations adsorb onto negatively charged metal surfaces through electrostatic interactions, forming an ordered molecular layer. The combined effect of these two factors generates a composite protective film during friction, further reducing direct contact between friction pairs and providing excellent friction reduction and anti-wear performance. Furthermore, phosphate ester anions form hydrogen bonds with metal oxides (such as Fe₂O₃) through P=O bonds, enhancing the strength of the adsorption film and significantly improving the lubrication performance of the base oil. In the phosphate ester ammonium salt ionic liquid provided in this application, during friction, the phosphate ester anions decompose to generate hard, wear-resistant layers such as iron phosphate (FePO₄) and polyphosphates, improving the anti-wear performance of the base oil. Moreover, the lone pair electrons of N in the ammonium cation can coordinate with the metal surface, enhancing the strength of the composite protective film and further improving the lubrication effect.

[0038] During the friction process, the ionic liquid can continuously replenish the consumed composite protective film, forming a dynamic equilibrium lubricating film. Furthermore, the high temperature in the contact area of ​​the friction pair promotes the decomposition of phosphate esters, and the newly generated FePO4 fills the wear area, achieving dynamic repair of the composite protective film.

[0039] Furthermore, the lubricating composition comprises the following components by weight percentage: 0.1-0.5% of a mixture of 1-5 kinds of ammonium phosphate ionic liquids and the balance base oil. In this application, the amount of ammonium phosphate ionic liquid added to the lubricating composition is very small (0.1-0.5 wt%), but it significantly improves the friction-reducing, anti-wear, and rust-preventing properties compared to the base oil.

[0040] Optionally, the lubricating composition may further include: 0.03-0.1% molybdenum disulfide, 0.02-0.05% 4,4'-dihydroxydiphenyl sulfide, 0.01-0.03% ethoxybenzamide, and at least one additive selected from friction modifiers, dispersants, and pour point depressants.

[0041] Specifically, 4,4'-dihydroxydiphenyl sulfide, as a lubricating additive, breaks the sulfide bond (-S-) under high temperature / high pressure friction to generate a chemical reaction film such as iron sulfide (FeS) or iron sulfate. The hydroxyl group (-OH) is adsorbed on the metal surface through hydrogen bonding to form a physical protective film, which enhances the boundary lubrication performance. It interacts with the composite protective film formed by the ammonium phosphate salt ionic liquid on the surface of the friction pair to form a lubricating film, which improves the hardness and continuity of the lubricating film and prevents metal adhesion, thereby significantly reducing the friction coefficient and wear volume between the friction pairs.

[0042] The phenolic hydroxyl group (-OH) in the 4,4'-dihydroxydiphenyl sulfide structure forms hydrogen bonds or dipole-dipole interactions with sulfur atoms on the surface of molybdenum disulfide under high temperature / high pressure during friction. Furthermore, during friction, the π electrons of the benzene ring in 4,4'-dihydroxydiphenyl sulfide interact with the sulfur layer of molybdenum disulfide through π-sulfur interactions (similar to π-π stacking). Simultaneously, the addition of 4,4'-dihydroxydiphenyl sulfide improves the dispersion stability of molybdenum disulfide in the base oil. This further enhances the stability and continuity of the lubricating film during friction, significantly improving the anti-friction and anti-wear properties of the base oil. Meanwhile, ethoxybenzamide contains benzene rings and amide bonds. The benzene rings, in conjunction with 4,4'-dihydroxydiphenyl sulfide, provide a certain degree of high-temperature stability, ensuring stable physicochemical properties in the lubricating composition when used in high-temperature environments. This prevents lubrication failure due to composition deterioration. Simultaneously, the amide and ether bonds interact with the metal surface during friction, forming a solid compound film of a certain thickness. This film shifts under shear force, consistently filling the space between the friction pairs, preventing contact between the metal surface and corrosive media such as air and water, thus improving the rust-preventive properties of the lubricating composition. Furthermore, the combined effect of ethoxybenzamide and 4,4'-dihydroxydiphenyl sulfide forms a stable lubricating film, maintaining its stability and contributing to improved lubrication performance.

[0043] Furthermore, 4,4'-dihydroxydiphenyl sulfide, in synergy with ammonium phosphate ionic liquid, ethoxybenzamide, and molybdenum disulfide, not only exhibits excellent rust prevention but also superior friction-reducing and anti-wear properties for friction pairs. The phenolic hydroxyl groups in 4,4'-dihydroxydiphenyl sulfide can adsorb onto the metal surface via hydrogen bonds, forming a physical protective film. Simultaneously, the benzene rings in 4,4'-dihydroxydiphenyl sulfide enhance the mechanical strength of the protective film. The layered structure of molybdenum disulfide easily slips under shear force, synergistically forming a dense and stable lubricating film with the lubricating films formed by ethoxybenzamide and 4,4'-dihydroxydiphenyl sulfide. This lubricating film effectively isolates moisture, oxygen, and other corrosive media (such as SO2, Cl-) during friction. -This avoids direct contact between corrosive media and the friction pair, thus providing excellent rust prevention and excellent friction reduction and wear resistance between the friction pairs.

[0044] The particle size of molybdenum disulfide is 50-80 nm.

[0045] The lubricating composition also includes at least one additive selected from friction modifier, dispersant, and pour point depressant. The amount of each of the friction modifier, dispersant, and pour point depressant added is 0.1-0.8 wt% of the lubricating composition.

[0046] Among them, friction modifiers can reduce the coefficient of friction, and examples include at least one of glyceryl oleate, octadecylamine, and molybdenum dithiophosphate. Its content is preferably 0.2-0.5 wt% of the lubricating composition.

[0047] Dispersants can improve the dispersibility of raw materials in a lubricating composition, which helps to improve the uniformity of the lubricating composition and thus improve its lubricating performance. Examples of dispersants include at least one of polyisobutylene succinimide and polyisobutylene succinate. Its content is preferably 0.1-0.4 wt% of the lubricating composition.

[0048] Pour point depressants can prevent oil from solidifying. Examples include at least one of polymethacrylate, alkyl naphthalene (such as long-chain alkyl with 10-20 carbon atoms), and ethylene-vinyl acetate copolymer, with a preferred content of 0.1-0.8 wt% of the lubricating composition.

[0049] Optionally, the base oil includes at least one of 150SN, PAO10, and base oil 5750.

[0050] Optionally, the preparation method of the lubricating composition includes: Weigh out 0.1-0.5% by mass of a mixture of one or more ammonium phosphate ionic liquids, 0.02-0.05% by mass of 4,4'-dihydroxydiphenyl sulfide, 0.03-0.1% by mass of molybdenum disulfide, 0.01-0.03% by mass of ethoxybenzamide, at least one additive selected from friction modifiers, dispersants, pour point depressants, and the balance base oil. Heat the mixture to 50-60°C and stir for 30-40 minutes while maintaining the temperature to obtain a lubricating composition.

[0051] The technical solution of this application will be illustrated in detail below with specific embodiments. Example 1

[0052] A method for preparing an ammonium phosphate salt ionic liquid specifically includes the following steps: Equimolar amounts of dibutyl phosphate and dodecylamine were placed in a 100 mL round-bottom flask and heated at 80 °C for 2 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain an ammonium phosphate ionic liquid, as shown in Formula II.

[0053]

[0054] Formula II Example 2 A method for preparing an ammonium phosphate salt ionic liquid specifically includes the following steps: Equimolar amounts of diisooctyl phosphate and dodecylamine were placed in a 100 mL round-bottom flask and heated at 80 °C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain an ammonium phosphate ionic liquid, as shown in Formula III.

[0055]

[0056] Formula III Example 3 A method for preparing an ammonium phosphate salt ionic liquid specifically includes the following steps: Equimolar amounts of dibutyl phosphate and N,N-dimethylhexadecanylamine were placed in a 100 mL round-bottom flask and heated at 82 °C for 10 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain an ammonium phosphate ionic liquid, as shown in Formula IV.

[0057]

[0058] Formula IV Example 4 A method for preparing an ammonium phosphate salt ionic liquid specifically includes the following steps: Equimolar amounts of diisooctyl phosphate and N,N-dimethylhexylamine were placed in a 100 mL round-bottom flask and heated at 85 °C for 18 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain an ammonium phosphate ionic liquid, as shown in Formula V.

[0059]

[0060] Formula V Experimental Example 1 Ammonium phosphate ionic liquids were synthesized in Examples 1-4. The proton and carbon NMR spectra of these liquids were characterized using nuclear magnetic resonance spectroscopy (NMR), phosphorus NMR was performed using multinuclear NMR spectroscopy, and high-resolution mass spectrometry (HMS) was used for further characterization. The structural characterization of these ammonium phosphate ionic liquids was thus completed. The characterization results are as follows: Structure characterization of the ammonium phosphate salt ionic liquid provided in Example 1 ( Figure 1 , Figure 2 , Figure 3 ): 1H NMR (400 MHz, CDCl3) δ: 8.57 (s, 3H), 3.81-3.76 (m, 4H), 2.76 (s, 2H), 1.59-1.23 (m, 28H), 0.92-0.85 (m, 9H). 13 C NMR (100 MHz, CDCl3) δ: 65.41,65.35, 39.65, 33.07, 32.99, 32.04, 29.79, 29.49, 29.46, 27.82, 27.10, 22.82,19.17, 14.23, 13.95. 31 P NMR (162 MHz, CDCl3) δ: 0.34 (s). Theoretical calculated value of cation: 186.2222, actual measured value of cation: 186.2229 [C 12 H 28 N] + Theoretical calculated value of anion: 209.0943, Actual measured value of anion: 209.0946 [C8H] 18 PO4] - .

[0061] The structure characterization of the ammonium phosphate salt ionic liquid provided in Example 2 ( Figure 4 , Figure 5 , Figure 6 ): 1 H NMR (400 MHz, CDCl3) δ: 8.63 (s, 3H), 3.71-3.65 (m, 4H), 2.76 (s, 2H), 1.50-1.23 (m, 38H), 0.88-0.84 (m, 15H). 13 C NMR (100 MHz, CDCl3) δ:68.24, 68.19, 40.52, 40.44, 39.70, 32.06, 30.15, 29.90, 29.82, 29.57, 29.50,29.18, 28.08, 27.25, 23.35, 23.28, 22.83, 14.25, 14.24. 31 P NMR (162 MHz, CDCl3) δ: 0.68 (s). Theoretical calculated value of cation: 186.2216, Actual measured value of cation: 186.2220 [C 12 H 28 N] +Theoretical calculated value of anion: 321.2195, Actual measured value of anion: 321.2210 [C] 16 H 34 PO4] - .

[0062] The structure characterization of the ammonium phosphate salt ionic liquid provided in Example 3 ( Figure 7 , Figure 8 , Figure 9 ): 1 H NMR (400 MHz, CDCl3) δ: 3.87-3.82 (m, 4H), 2.84 (s, 1H), 2.70 (s, 6H), 1.91-1.22 (m, 38H), 0.90-0.83 (m, 9H). 13 C NMR (100 MHz, CDCl3) δ: 65.36,65.30, 57.87, 42.84, 33.05, 32.98, 32.02, 29.79, 29.77, 29.76, 29.74, 29.68,29.60, 29.51, 29.45, 29.25, 26.85, 22.78, 19.15, 14.21, 13.93. 31 P NMR (162MHz, CDCl3) δ: 1.50 (s). Theoretical cation value: 242.2848, Actual cation value: 242.2840 [C 16 H 36 N] + Theoretical calculated value of anion: 209.0943, Actual measured value of anion: 209.0949 [C88H] 18 PO4] - .

[0063] The structure characterization of the ammonium phosphate salt ionic liquid provided in Example 4 ( Figure 10 , Figure 11 , Figure 12 ): 1 H NMR (400 MHz, CDCl3) δ: 3.76-3.72 (m, 4H), 2.85 (s, 1H), 2.70 (s, 6H), 1.71-1.23 (m, 48H), 0.87-0.84 (m, 15H). 13C NMR (100 MHz, CDCl3) δ:67.96, 67.90, 57.85, 42.81, 40.53, 40.45, 32.03, 30.24, 29.81, 29.79, 29.78,29.76, 29.70, 29.62, 29.55, 29.47, 29.29, 29.17, 26.89, 24.32, 23.49, 23.24,22.80, 14.24, 11.11. 31 P NMR (162 MHz, CDCl3) δ. Theoretical calculated value for cation: 242.2848, actual measured value for cation: 242.2840 [C 16 H 36 N] + Theoretical calculated value of anion: 321.2195, Actual measured value of anion: 321.2210 [C] 16 H 34 PO4] - .

[0064] The structure of the ammonium phosphate ion liquid was characterized by its proton, carbon, and phosphorus NMR spectra, demonstrating the successful synthesis of the corresponding ammonium phosphate ion liquid.

[0065] Example 5 A method for preparing a lubricating composition, specifically comprising: (1) Preparation of ionic liquid mixture: The ammonium phosphate salt ionic liquids provided in Examples 1, 2, 3 and 4 were mixed together in a weight ratio of 1:1:1:1 and heated at 80°C for 2 hours to obtain the ionic liquid mixture; (2) Preparation of lubricating composition: Weigh 99.9g of base oil (150SN) and 0.1g of ionic liquid mixture, heat to 50℃, stir for 30min to obtain lubricating composition 1.

[0066] Example 6 A method for preparing a lubricating composition, specifically comprising: The difference from Example 5 is that: (2) Preparation of lubricating composition: Weigh 99.7g of base oil (150SN) and 0.3g of ionic liquid mixture, heat to 50℃, stir for 30min to obtain lubricating composition 2.

[0067] Example 7 A method for preparing a lubricating composition, specifically comprising: The difference from Example 5 is that: (2) Preparation of lubricating composition: Weigh 99.5g of base oil (150SN) and 0.5g of ionic liquid mixture, heat to 50℃, stir for 40min to obtain lubricating composition 3.

[0068] Comparative Example 1 A method for preparing a lubricating composition, specifically comprising: The difference from Example 5 is that: The lubricant additive is selected from the commonly used AW6110 on the market.

[0069] (2) Preparation of lubricating composition: Weigh 99.9g of base oil (150SN) and 0.1g of AW6110 additive, heat to 50℃, stir for 30min to obtain lubricating composition 4.

[0070] Comparative Example 2 A method for preparing a lubricating composition, specifically comprising: The lubricant additive is selected from the commonly used AW6110 on the market.

[0071] The difference from Example 5 is that: (2) Preparation of lubricating composition: Weigh 99.5g of base oil (150SN) and 0.5g of AW6110 additive, heat to 50℃, stir for 30min to obtain lubricating composition 4.

[0072] Comparative Example 3 A method for preparing a lubricating composition, specifically comprising: The difference from Example 5 is that: 100g base oil (150SN), no lubricating additives added.

[0073] Experimental Example 2 Thermal stability test The thermal stability of the ammonium phosphate ionic liquids provided in Examples 1-4 and the mixtures of ionic liquids provided in Examples 5-7 were tested using a STA449-F3 (NETZSCH, TGA-DSC) simultaneous thermal analyzer. The test conditions were: nitrogen atmosphere, heating rate of 10℃ / min, and heating range of room temperature to 600℃. The measured thermal stability properties of the lubricating compositions are shown in Table 1.

[0074] Table 1

[0075] As shown in Table 1, the ammonium phosphate ionic liquid and the ionic liquid mixture provided in this application both exhibit high thermal stability. This indicates that the ionic liquid can be used in high-temperature lubrication environments, demonstrating greater versatility in application environments.

[0076] Experimental Example 2 Friction performance test The friction-reducing and anti-wear properties of the lubricating compositions provided in Examples 5-7 and Comparative Examples 1-3 were tested.

[0077] The tribological properties were tested using an SRV-IV friction and wear testing machine manufactured by Optimol Grease GmbH, Germany, via ball-disc contact. Friction tests were conducted at 25℃ and 100℃, with a test frequency of 50Hz, a load of 200N, an amplitude of 1mm, and a test time of 30min. The tests used 10mm diameter GCr15 steel balls and 24mm diameter, 7.9mm thick GCr15 steel discs. Each test was performed in at least three parallel runs, and the average value was taken. The test results are shown in Table 2.

[0078] Table 2

[0079] As shown in Table 2, compared to Comparative Example 3, the lubricating compositions of Comparative Examples 1, 2, and Examples 5-7 all exhibited better friction-reducing and anti-wear properties at both room temperature (25°C) and high temperature (100°C). At room temperature (25°C), both the ionic liquid additive and the AW6110 additive effectively reduced the coefficient of friction of the base oil 150SN. In Example 7, the average coefficient of friction of the lubricating composition with 0.5% ionic liquid mixture was 0.1213, which was reduced by about 35% compared to the base oil 150SN, and by about 38% compared to the AW6110 additive at the same concentration (Comparative Example 2). Simultaneously, the wear volume was reduced by 89% compared to the base oil 150SN, and by 42% compared to the AW6110 additive at the same concentration (Comparative Example 2). This indicates that at room temperature, the addition of the ammonium phosphate ionic liquid additive provided in this application can effectively improve the friction-reducing and anti-wear properties of 150SN, and its performance is superior to AW6110 at the same concentration.

[0080] At a high temperature of 100°C, the lubricating compositions of Examples 5-7 still exhibited superior lubrication performance compared to 150SN base oil and AW6110. The coefficient of friction in Example 7 was reduced compared to low-temperature conditions. The average coefficient of friction in Example 7 was reduced by 43% and 38% compared to 150SN base oil (Comparative Example 3) and AW6110 (Comparative Example 2), respectively. Furthermore, it was calculated that the average wear volume of the lubricating composition (Example 7) with the addition of 0.5% ionic liquid mixture was reduced by approximately 91% and 52% compared to 150SN base oil (Comparative Example 3) and AW6110 (Comparative Example 2), respectively.

[0081] This indicates that under more demanding high-temperature environments, ammonium phosphate ionic liquids exhibit better friction-reducing and anti-wear effects as lubricant additives. This is because the tribochemical reaction proceeds faster under high-temperature catalysis, leading to more ammonium phosphate ionic liquids participating in the friction reaction process, producing more compounds with friction-reducing and anti-wear properties, and forming a tribochemical reaction protective film on the wear surface. This demonstrates that the addition of ammonium phosphate ionic liquids at high temperatures can also effectively improve the friction-reducing and anti-wear performance of 150SN, and the performance of ammonium phosphate ionic liquid additives at the same concentration is superior to AW6110.

[0082] Experimental Example 3 Wear resistance test The anti-wear properties of the lubricating compositions provided in Examples 5-7 and Comparative Examples 1-3 were tested. The test method followed the standard "Determination of Anti-wear Properties of Lubricating Oils (Four-ball machine method)" (SH / T0189-1992), measuring anti-wear properties under the following conditions: temperature 75℃, rotation speed 1200 r / min, and load 40 kg. Each test was performed in at least three parallel trials, and the average value was taken. The test results are shown in Table 3.

[0083] Table 3

[0084] As clearly shown in Table 3, base oil 150SN (Comparative Example 3) exhibits the worst anti-wear performance, with an average friction coefficient of approximately 0.0696. The anti-wear performance of the base oil was significantly improved after adding 0.5 wt% of an ammonium phosphate ionic liquid mixture (Example 7). Similarly, the anti-wear performance of the base oil was also significantly improved after adding 0.5 wt% of AW6110 (Comparative Example 2). However, the performance of the ammonium phosphate ionic liquid additive at the same concentration was significantly better than that of the AW6110 additive.

[0085] Experiment Example 4 Rust prevention performance test The rust-preventive properties of the lubricating compositions provided in Examples 5-7 and Comparative Examples 1-3 were tested. The tests were conducted according to standard MIL-PRF-17331J. Test conditions: Before testing, the lubricating compositions were washed with water as follows: 300 grams of the test lubricating composition were soaked in 50 grams of water at 90°C for 30 minutes using a beaker and stirrer as specified in ASTM D665. After stirring for 30 minutes, the mixture was transferred to a separation funnel and allowed to separate. The water layer was then drained, and the oil phase was tested according to GB / T 11143-2008 (Method B) for 24 hours. The steel bar surface was observed for rust. Each test was performed in at least three parallel trials. The test results are shown in Table 4.

[0086] Table 4

[0087] As shown in Table 4, ammonium phosphate salt ionic liquid has excellent rust prevention properties as a lubricating additive, and it still has qualified rust prevention properties even when the addition amount is only 0.1wt%.

[0088] Example 8 A method for preparing a lubricating composition, specifically comprising: The difference from Example 5 is that: (2) Preparation of lubricating composition: Weigh 99.04g of base oil (150SN), 0.5g of ionic liquid mixture, 0.02g of 4,4'-dihydroxydiphenyl sulfide, 0.01g of ethoxybenzamide, 0.03g of molybdenum disulfide, 0.2g of friction modifier (glyceryl oleate), 0.1g of dispersant (polyisobutylene succinate), and 0.1g of pour point depressant (polymethyl methacrylate). Heat to 50℃ and stir for 30min to obtain lubricating composition 4.

[0089] Example 9 A method for preparing a lubricating composition, specifically comprising: The difference from Example 5 is that: (2) Preparation of lubricating composition: Weigh 98.3g of base oil (150SN), 0.5g of ionic liquid mixture, 0.03g of 4,4'-dihydroxydiphenyl sulfide, 0.02g of ethoxybenzamide, 0.05g of molybdenum disulfide, 0.3g of friction modifier (glyceryl oleate), 0.3g of dispersant (polyisobutylene succinate), and 0.5g of pour point depressant (polymethyl methacrylate). Heat to 55°C and stir for 30min to obtain lubricating composition 5.

[0090] Example 10 A method for preparing a lubricating composition, specifically comprising: The difference from Example 5 is that: (2) Preparation of lubricating composition: Weigh 97.62g of base oil (150SN), 0.5g of ionic liquid mixture, 0.05g of 4,4'-dihydroxydiphenyl sulfide, 0.03g of ethoxybenzamide, 0.1g of molybdenum disulfide, 0.5g of friction modifier (glyceryl oleate), 0.4g of dispersant (polyisobutylene succinate), and 0.8g of pour point depressant (polymethyl methacrylate). Heat to 60℃ and stir for 30min to obtain lubricating composition 6.

[0091] Comparative Example 4 A method for preparing a lubricating composition, specifically comprising: The difference from Example 9 is that: (2) Preparation of lubricating composition: Weigh 99.4g of base oil (150SN), 0.5g of ionic liquid mixture, 0.03g of 4,4'-dihydroxydiphenyl sulfide, 0.02g of ethoxybenzamide, and 0.05g of molybdenum disulfide. Heat to 50°C and stir for 30min to obtain lubricating composition 7.

[0092] Comparative Example 5 A method for preparing a lubricating composition, specifically comprising: The difference from Example 9 is that: (2) Preparation of lubricating composition: Weigh 99.47g of base oil (150SN), 0.5g of ionic liquid mixture, and 0.03g of 4,4'-dihydroxydiphenyl sulfide, heat to 50℃, and stir for 30min to obtain lubricating composition 8.

[0093] Comparative Example 6 A method for preparing a lubricating composition, specifically comprising: The difference from Example 9 is that: (2) Preparation of lubricating composition: Weigh 99.45g of base oil (150SN), 0.5g of ionic liquid mixture, and 0.05g of molybdenum disulfide, heat to 50℃, and stir for 30min to obtain lubricating composition 9.

[0094] Comparative Example 7 A method for preparing a lubricating composition, specifically comprising: The difference from Example 9 is that: (2) Preparation of lubricating composition: Weigh 99.48g of base oil (150SN), 0.5g of ionic liquid mixture, and 0.02g of ethoxybenzamide, heat to 50℃, stir for 30min to obtain lubricating composition 10.

[0095] Experimental Example 5 The friction-reducing and wear-resistant properties of Examples 8-10 and Comparative Examples 4-7 were tested using the test method of Experimental Example 2. At least three parallel tests were performed for each experiment, and the average value was taken. The test results are shown in Table 5.

[0096] Table 5

[0097] As shown in Table 5, the addition of 4,4'-dihydroxydiphenyl sulfide, ethoxybenzamide, molybdenum disulfide, friction modifier, dispersant, and pour point depressant to the lubricating composition significantly improved the tribological properties at both room temperature and high temperature compared to Example 7. Comparing Examples 8-10 with Comparative Examples 5, 6, and 7, it was found that the addition of 4,4'-dihydroxydiphenyl sulfide, ethoxybenzamide, and molybdenum disulfide significantly improved the tribological properties compared to the addition of friction modifier, dispersant, and pour point depressant (comparative examples).

[0098] Meanwhile, by comparing Examples 8-10 with Comparative Examples 5, 6, and 7, it was found that the simultaneous addition of ammonium phosphate ionic liquid, 4,4'-dihydroxydiphenyl sulfide, ethoxybenzamide, and molybdenum disulfide significantly improved the tribological properties of the base oil. Moreover, the improvement in anti-wear performance at high temperature was better than at room temperature. This indicates that 4,4'-dihydroxydiphenyl sulfide, ethoxybenzamide, and molybdenum disulfide can synergistically work with ammonium phosphate ionic liquid to form a lubricating film on the surface of the friction pair under high temperature / high pressure friction. This improves the hardness, stability, and continuity of the lubricating film, prevents direct contact between the friction pairs, and thus significantly reduces the coefficient of friction and wear volume between the friction pairs.

[0099] Experimental Example 6 Rust prevention performance test The rust-preventive properties of Examples 7-10 and Comparative Examples 2-7 were tested.

[0100] The testing standards are as follows: Rust-preventive grease film removal test (SH / T 0212), petroleum product copper strip corrosion test (GB / T5096), rust-preventive grease damp heat test (GB / T 2361), and rust-preventive grease salt spray test (SH / T 0081). Each test was performed in at least three parallel runs, and the average value was taken. The test results are shown in Table 6.

[0101] Table 6

[0102] As shown in Table 6, the ammonium phosphate ionic liquid provided in this application exhibits excellent resistance to corrosion under salt spray and humid heat conditions. Comparing Examples 8-10 with Comparative Examples 4-5, it was found that adding the ammonium phosphate ionic liquid to base oil 150SN significantly improves the rust prevention and lubrication properties of the base oil. Simultaneously, 4,4'-dihydroxydiphenyl sulfide, ethoxybenzamide, ammonium phosphate ionic liquid, and molybdenum disulfide work synergistically to provide excellent rust prevention for friction pairs. The phenolic hydroxyl groups in 4,4'-dihydroxydiphenyl sulfide can be adsorbed onto the metal surface through hydrogen bonds, forming a physical protective film. Ethoxybenzamide forms a solid compound film of a certain thickness with the metal surface, which shifts under shear force and always fills the space between the friction pairs, thereby improving the rust prevention performance of the lubricating composition. At the same time, the benzene rings in 4,4'-dihydroxydiphenyl sulfide and ethoxybenzamide together improve the mechanical strength of the protective film. In synergy with ammonium phosphate ionic liquid and molybdenum disulfide, a tribochemical reaction occurs under high temperature / high pressure friction, generating a chemical reaction film. This film, in conjunction with the physical adsorption film, forms a dense lubricating film. This lubricating film can isolate moisture, oxygen, and other corrosive media during friction, preventing direct contact between corrosive media and the friction pairs, thus providing excellent rust prevention.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A phosphate ester ammonium salt ionic liquid, characterized in that, The cations of the ammonium phosphate ionic liquid are ammonium salt cations with different alkyl chain lengths, and the anions are phosphate esters with different chain lengths. The ammonium phosphate ionic liquid includes the general formula shown in Formula I: Formula I In Formula I, R, R1, and R2 are each independently selected from C1-C18 alkyl groups.

2. The ammonium phosphate salt ionic liquid according to claim 1, characterized in that, R, R1, and R2 are each independently selected from C1-C18, and the alkyl group is any one of straight-chain, branched, or cyclic.

3. The ammonium phosphate salt ionic liquid according to claim 1, characterized in that, R, R1, and R2 are each independently selected from any one of methyl, ethyl, propyl, butyl, isobutyl, pentyl, isopentyl, octyl, isooctyl, decyl, isodecyl, dodecyl, tetradecyl, hexadecyl, and octadecyl.

4. A method for preparing an ammonium phosphate salt ionic liquid, characterized in that, The preparation method is used to prepare the ammonium phosphate salt ionic liquid according to any one of claims 1-3, and the preparation method includes the following steps: Alkylamine and phosphate ester were placed in a round-bottom flask and reacted at 80-85℃ for 2-24 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain the ammonium phosphate ester ionic liquid.

5. The method for preparing the ammonium phosphate salt ionic liquid according to claim 4, characterized in that, The molar ratio of the alkylamine to the phosphate ester is 1:

1.

6. The application of an ammonium phosphate ionic liquid in a lubricating composition, wherein the ammonium phosphate ionic liquid is the ammonium phosphate ionic liquid according to any one of claims 1-3, or the ammonium phosphate ionic liquid prepared by the method of claim 4 or 5, characterized in that, The application of the ammonium phosphate salt ionic liquid as a lubricant additive in lubrication compositions.

7. The application of the ammonium phosphate salt ionic liquid according to claim 6 in a lubricating composition, characterized in that, The lubricating composition comprises the following components in weight percentages: 0.1-0.5% of one or more of the ammonium phosphate salt ionic liquid mixtures and the balance base oil.

8. The application of the ammonium phosphate salt ionic liquid according to claim 6 in a lubricating composition, characterized in that, The lubricating composition further includes: 0.03-0.1% molybdenum disulfide, 0.02-0.05% 4,4'-dihydroxydiphenyl sulfide, 0.01-0.03% ethoxybenzamide, and at least one additive selected from friction modifiers, dispersants, and pour point depressants.

9. The application of the ammonium phosphate salt ionic liquid according to claim 7 in a lubricating composition, characterized in that, The base oil includes at least one of 150SN, PAO10, and base oil 5750.

10. The application of the ammonium phosphate salt ionic liquid according to claim 9 in a lubricating composition, characterized in that, The method for preparing the lubricating composition includes: Weigh out one or more ammonium phosphate ionic liquids, 4,4'-dihydroxydiphenyl sulfide, molybdenum disulfide, ethoxybenzamide, at least one additive selected from friction modifiers, dispersants, pour point depressants, and the balance base oil by mass percentage, heat to 50-60°C, and stir for 30-40 minutes while maintaining the temperature to obtain the lubricating composition.

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