Thiophosphate proton type ionic liquid additive as well as preparation method and application thereof

Abstract

The invention relates to a phosphorothioate proton type ionic liquid additive. The structural formula of the additive is shown in the specification, wherein R is a C1-C20 alkyl group. Meanwhile, the invention further discloses a preparation method and application of the additive. The additive disclosed by the invention has excellent antifriction and antiwear performance and bearing capacity in the composite lithium-based lubricating grease, and the technical problem that the key performance of the lubricating grease is not sufficiently improved by the existing additive is solved.

Description

Technical Field

[0001] This invention relates to the field of lubricant additives, and more particularly to proton-type ionic liquid additives of thiophosphate esters, their preparation methods, and applications. Background Technology

[0002] The demand for efficient, environmentally friendly, and long-life lubrication technologies in high-end machinery and equipment is becoming increasingly urgent. As a key lubricant, the performance of grease largely depends on the effectiveness of its additives. Anti-wear and extreme pressure additives, acting on the surfaces of friction pairs, form a protective film that directly determines the load-bearing capacity and reliability of the lubrication system under harsh operating conditions. However, traditional halogen-containing additives are prone to generating corrosive substances during friction, posing potential hazards to the environment and the equipment itself, making it difficult to meet the stringent requirements of high-end equipment such as wind turbine bearings for green and highly reliable lubrication. Therefore, developing novel high-performance additives that combine friction reduction, anti-wear properties, and extreme pressure capabilities has become an important research direction in the lubrication field.

[0003] Proton-type ionic liquids, as structurally designable additives, exhibit great potential due to their excellent physicochemical properties and tunable tribochemical activity. However, the key to overcoming their application bottleneck lies in how to enable them to efficiently perform extreme pressure anti-wear functions in complex grease systems through rational molecular design. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a high-performance proton-type ionic liquid additive of thiophosphate ester.

[0005] Another technical problem to be solved by the present invention is to provide a method for preparing the thiophosphate proton-type ionic liquid additive.

[0006] The third technical problem to be solved by the present invention is to provide the application of this thiophosphate proton-type ionic liquid additive.

[0007] To solve the above problems, the thiophosphate proton-type ionic liquid additive of the present invention is characterized by the following structural formula: Where: R represents C1~C 20 alkyl.

[0008] The preparation method of the proton-type ionic liquid additive of thiophosphate ester as described above includes the following steps: S1 synthesis of cationic precursors: At -20℃ to -5℃, n-butylamine, triethylamine, and excess dichloromethane solvent were sequentially added to container A. Then, diphenyl chlorophosphate was added dropwise. After the addition was complete, the reaction was carried out at room temperature for 12 to 24 hours. After removing the dichloromethane solvent, the mixture was placed in a vacuum drying oven at 70℃ for 12 to 24 hours to obtain the cationic precursor. The molar ratio of n-butylamine to triethylamine was 1:1.0 to 1.2, and the molar ratio of n-butylamine to diphenyl chlorophosphate was 1:1.0 to 1.1. S2 synthesis of anion precursors: Phosphorus pentasulfide and excess toluene were added together to container B equipped with a tail gas treatment device, and then alkylphenol was added. The reaction was carried out at 80℃~100℃ for 24 h~48 h. After the reaction was completed, the toluene solvent and unreacted raw materials were removed by vacuum distillation to obtain the anionic precursor. The molar ratio of phosphorus pentasulfide to alkylphenol was 1:3.3~4.0. S3 Synthesis of Target Ionic Liquid: The cationic precursor and excess anhydrous ethanol solvent were added sequentially to container C. Then, the anionic precursor was rapidly added dropwise and stirred at room temperature for 24 h to 48 h. After the reaction, the ethanol solvent was removed by rotary evaporation, and then the mixture was dried under vacuum at 70 °C for 12 h to 24 h to obtain the target ionic liquid. The molar ratio of the cationic precursor to the anionic precursor was 1:0.98 to 1.02.

[0009] In step S2, alkylphenol refers to C1~C60 phenols. 20 One of the alkylphenols.

[0010] The application of the proton-type ionic liquid additives of thiophosphate esters as described above is characterized in that: the additive is used to prepare composite lithium-based grease.

[0011] The composite lithium-based grease is prepared by the following method: 12-hydroxystearic acid and azelaic acid are dissolved in 2 / 3 of the base oil at 60-80℃. Then, a lithium hydroxide aqueous solution with a mass concentration of 9%-11% is added to the solution, and the mixture is subjected to a saponification reaction at 60-80℃ for 2 hours. The mixture is then heated to 200-220℃ for high-temperature refining. After 5-10 minutes, the remaining 1 / 3 of the base oil is added, and the mixture is allowed to cool naturally to room temperature. The mixture is then milled three times using a three-roll mill to obtain the base grease. Then, 1-5% of the additives are added to the base grease, and the mixture is milled three times again using a three-roll mill to obtain a composite lithium-based grease containing additives. The mass ratio of azelaic acid, 12-hydroxystearic acid, base oil, and lithium hydroxide aqueous solution is 1:12.5-13.0:160-165:13-14.

[0012] Compared with the prior art, the present invention has the following advantages: 1. This invention proposes a novel design strategy for proton-type ionic liquids that combines rigidity and flexibility from a molecular engineering perspective. By precisely controlling the length of the anionic alkyl chain and synergizing with the rigid aromatic ring structure, it aims to balance the interfacial adsorption strength, ordered arrangement ability, and compatibility of additive molecules in greases.

[0013] 2. The series of proton-type ionic liquids with different alkyl chain structures described in this invention have excellent friction-reducing and anti-wear properties and load-bearing capacity in composite lithium-based greases, solving the technical problem that existing additives are insufficient in improving the key performance of greases. Attached Figure Description

[0014] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0015] Figure 1 This is the real-time friction coefficient curve of the lubricating grease sample of the present invention.

[0016] Figure 2 The average coefficient of friction and wear amount of the lubricating grease sample of this invention are shown.

[0017] Figure 3 This is for the extreme pressure performance test of the lubricating grease sample of the present invention. Detailed Implementation

[0018] Thiophosphate ester proton-type ionic liquid additive, the structural formula of which is shown below: Where: R represents C1~C 20 Alkyl groups, preferably C5-C 12 alkyl.

[0019] Its preparation method includes the following steps: S1 synthesis of cationic precursors: At -20℃ to -5℃, n-butylamine, triethylamine, and excess dichloromethane solvent were sequentially added to container A. Then, diphenyl chlorophosphate was added dropwise. After the addition was complete, the reaction was carried out at room temperature for 12 to 24 hours. After removing the dichloromethane solvent, the mixture was placed in a vacuum drying oven at 70℃ for 12 to 24 hours to obtain the cationic precursor. The molar ratio of n-butylamine to triethylamine was 1:1.0 to 1.2, and the molar ratio of n-butylamine to diphenyl chlorophosphate was 1:1.0 to 1.1.

[0020] S2 synthesis of anion precursors: Phosphorus pentasulfide and excess toluene were added together to container B equipped with a tail gas treatment device, and then alkylphenol was added. The reaction was carried out at 80℃~100℃ for 24 h~48 h. After the reaction was completed, the toluene solvent and unreacted raw materials were removed by vacuum distillation to obtain the anionic precursor. The molar ratio of phosphorus pentasulfide to alkylphenol was 1:3.3~4.0.

[0021] Wherein: alkylphenols refer to C1~C 20 One of the alkylphenols, preferably C5-C 12 One of the alkylphenols.

[0022] S3 Synthesis of Target Ionic Liquid: The cationic precursor and excess anhydrous ethanol solvent (mass fraction ≥99.7%) were added sequentially to container C. Then, the anionic precursor was rapidly added dropwise and stirred at room temperature for 24 h to 48 h. After the reaction, the ethanol solvent was removed by rotary evaporation, and then the mixture was dried under vacuum at 70 °C for 12 h to 24 h to obtain the target ionic liquid. The molar ratio of the cationic precursor to the anionic precursor was 1:0.98 to 1.02.

[0023] Application of thiophosphate ester proton-type ionic liquid additives: These additives are used in the preparation of complex lithium-based greases. The complex lithium-based greases are prepared according to the following method: 12-hydroxystearic acid and azelaic acid are dissolved in 2 / 3 of the base oil at 60-80℃. Then, a 9%-11% lithium hydroxide aqueous solution is added to the mixture, and a saponification reaction is carried out at 60-80℃ for 2 hours. The mixture is then heated to 200-220℃ for high-temperature refining. After 5-10 minutes, the remaining 1 / 3 of the base oil is added, and the mixture is allowed to cool naturally to room temperature. The mixture is then milled three times using a three-roll mill to obtain the base grease. Then, 1-5% of the additive is added to the base grease, and the mixture is milled three times again using a three-roll mill to obtain a composite lithium-based grease containing additives. The mass ratio (g / g) of azelaic acid, 12-hydroxystearic acid, base oil, and lithium hydroxide aqueous solution is 1:12.5-13.0:160-165:13-14.

[0024] Example 1 At -10°C, n-butylamine (0.1 mol, 7.31 g) and triethylamine (0.1 mol, 10.12 g) were sequentially added to a flask with dichloromethane solvent. Then, diphenyl chlorophosphate (0.1 mol, 26.86 g) was added dropwise to the flask. After the addition was complete, the reaction was carried out at room temperature for 12 h. After removing the dichloromethane solvent, the flask was placed in a vacuum drying oven at 70°C for 12 h to obtain the cationic precursor.

[0025] Phosphorus pentasulfide (0.055 mol, 12.23 g) and toluene were added together to a three-necked flask equipped with a tail gas treatment device. Then, pentylphenol (0.2 mol, 32.85 g) was added to the above system, and the reaction was carried out at 95 °C for 24 h. After the reaction was complete, the toluene solvent and unreacted reactants were removed by vacuum distillation to obtain the anionic precursor.

[0026] The cationic precursor (0.1 mol, 30.53 g) and anhydrous ethanol solvent were added sequentially to a flask. Then, the anionic precursor (0.1 mol, 42.26 g) was rapidly added dropwise to the flask and stirred at room temperature for 24 h. After the reaction, the ethanol solvent was removed by rotary evaporation, and the product was dried under vacuum at 70 °C for 12 h to obtain the target ionic liquid product, abbreviated as [DPA][PP].

[0027] The molecular structure of [DPA][PP] was characterized by 1H NMR spectroscopy, proving the successful synthesis of the target ionic liquid. The results are as follows.

[0028] 1 H NMR (CDCl3, 600 MHz): δ 0.82-1.59 (m, 25H, -CH3, -CH2-), 2.43-2.52(m, 2H, -CH2-), 3.01-3.06 (m, 2H, -CH2-), 4.20-4.25 (m, 2H, -CH2-N + ), 5.61 (s,2H, -N + H2), 6.74 (d, 4H, -CH), 6.98 (d, 4H, -CH), 7.07-7.36 (m, 10H, -CH). 12-hydroxystearic acid (72.0 g) and azelaic acid (5.7 g) were dissolved in 614.0 g of base oil at 80 °C. Then, 77.0 g of 10% lithium hydroxide aqueous solution was added and the mixture was saponified at 80 °C for 2 h. The mixture was then heated to 200 °C for high-temperature refining. After 5 min, the remaining 306 g of base oil was added and the mixture was allowed to cool naturally to room temperature. The mixture was then ground three times using a three-roll mill to obtain the base grease LCG.

[0029] Take 1 g of [DPA][PP] and add it to 99 g of LCG. After stirring thoroughly, grind it three times using a three-roll mill to obtain a grease containing 1% by mass of ionic liquid additive, denoted as LCG+1% [DPA][PP].

[0030] Take 3 g of [DPA][PP] and add it to 97 g of LCG. After stirring thoroughly, grind it three times using a three-roll mill to obtain a grease containing 3% ionic liquid additive by mass, denoted as LCG+3% [DPA][PP].

[0031] Friction reduction and wear resistance performance test: The lubricating performance of LCG+1% [DPA][PP] and LCG+3% [DPA][PP] as grease additives was investigated on a four-ball friction and wear testing machine and compared with the base grease (LCG). The load was 392 N, the temperature was 75 ℃, the rotation speed was 1200 r / min, and the test time was 60 min. Both upper and lower test balls were made of GCr15 bearing steel with the following physical parameters: diameter 12.7 mm, hardness HRC 60-63. After the friction test, the wear scar diameter of the steel balls was measured using an optical microscope. The results are shown in [Figure 1]. Figures 1-2 .

[0032] Depend on Figures 1-2 It can be seen that the friction coefficient and wear amount of [DPA][PP] at the two different concentrations are better than those of the base grease, showing excellent friction reduction and anti-wear performance.

[0033] Extreme pressure performance test: The extreme pressure performance of LCG+1% [DPA][PP] and LCG+3% [DPA][PP] as grease additives was investigated on a four-ball friction and wear testing machine and compared with the base grease (LCG). The rotational speed was 1770 r / min, the test time was 10 s, and both the upper and lower test balls were made of GCr15 bearing steel with the following physical parameters: diameter 12.7 mm, hardness HRC 60-63. The maximum non-seizure load and sintering load were recorded, and the results are shown below. Figure 2 .

[0034] Depend on Figure 3 It can be seen that the P values ​​of [DPA] and [PP] at two different concentrations are different. B Value and P D The values ​​are all superior to the base grease, demonstrating excellent load-bearing capacity.

[0035] In summary, this invention designs and prepares a novel ionic liquid additive. This novel ionic liquid, as an additive for composite lithium-based greases, exhibits excellent friction reduction, anti-wear, and extreme pressure properties, and has broad application prospects as a high-performance extreme pressure anti-wear additive for greases.

[0036] Example 2 The synthesis of the cationic precursor was the same as in Example 1.

[0037] Phosphorus pentasulfide (0.055 mol, 12.23 g) and toluene were added together to a three-necked flask equipped with a tail gas treatment device. Then, nonylphenol (0.2 mol, 44.07 g) was added to the above system, and the reaction was carried out at 95 °C for 24 h. After the reaction was completed, the toluene solvent and unreacted raw materials were removed by vacuum distillation to obtain the anionic precursor.

[0038] Synthesis of the target ionic liquid: The cationic precursor (0.1 mol, 30.53 g) and ethanol solvent were added sequentially to a flask. Subsequently, the anionic precursor (0.1 mol, 53.48 g) was rapidly added dropwise to the flask and stirred at room temperature for 24 h. After the reaction, the ethanol solvent was removed by rotary evaporation, and the product was dried under vacuum at 70 °C for 12 h to obtain the target ionic liquid product, abbreviated as [DPA][NP].

[0039] Add 1 g of [DPA][NP] to 99 g of LCG, mix thoroughly, and then grind three times using a three-roll mill to obtain a grease containing 1% ionic liquid additive by mass, denoted as LCG+1% [DPA][NP]. The preparation of the base grease LCG is the same as in Example 1.

[0040] Take 3 g of [DPA][NP] and add it to 97 g of LCG. After stirring thoroughly, grind it three times using a three-roll mill to obtain a grease containing 3% ionic liquid additive by mass, denoted as LCG+3% [DPA][NP].

[0041] Example 3 The synthesis of the cationic precursor was the same as in Example 1.

[0042] Phosphorus pentasulfide (0.055 mol, 12.23 g) and toluene were added together to a three-necked flask equipped with a tail gas treatment device. Then, dodecylphenol (0.2 mol, 52.49 g) was added to the above system, and the reaction was carried out at 95 °C for 24 h. After the reaction was complete, the toluene solvent and unreacted reactants were removed by vacuum distillation to obtain the anionic precursor.

[0043] Synthesis of the target ionic liquid: The cationic precursor (0.1 mol, 30.53 g) and ethanol solvent were added sequentially to a flask. Subsequently, the anionic precursor (0.1 mol, 61.90 g) was rapidly added dropwise to the flask and stirred at room temperature for 24 h. After the reaction, the ethanol solvent was removed by rotary evaporation, and the product was dried under vacuum at 70 °C for 12 h to obtain the target ionic liquid product, abbreviated as [DPA][DP].

[0044] Take 1 g of [DPA][DP] and add it to 99 g of LCG. After thorough mixing, grind the mixture three times using a three-roll mill to obtain a grease containing 1% ionic liquid additive by mass, denoted as LCG+1% [DPA][DP]. The preparation of the base grease LCG is the same as in Example 1.

[0045] Take 3 g of [DPA][DP] and add it to 97 g of LCG. After stirring thoroughly, grind it three times using a three-roll mill to obtain a grease containing 3% ionic liquid additive by mass, denoted as LCG+3% [DPA][DP].

Claims

1. A proton-type ionic liquid additive of thiophosphate ester, characterized in that: The structural formula of the additive is shown below: Where: R represents C1~C 20 alkyl.

2. The preparation method of the proton-type ionic liquid additive of thiophosphate as described in claim 1, comprising the following steps: S1 synthesis of cationic precursors: At -20℃ to -5℃, n-butylamine, triethylamine, and excess dichloromethane solvent were sequentially added to container A. Then, diphenyl chlorophosphate was added dropwise. After the addition was complete, the reaction was carried out at room temperature for 12 to 24 hours. After removing the dichloromethane solvent, the mixture was placed in a vacuum drying oven at 70℃ for 12 to 24 hours to obtain the cationic precursor. The molar ratio of n-butylamine to triethylamine was 1:1.0 to 1.2, and the molar ratio of n-butylamine to diphenyl chlorophosphate was 1:1.0 to 1.

1. S2 synthesis of anion precursors: Phosphorus pentasulfide and excess toluene were added together to container B equipped with a tail gas treatment device, and then alkylphenol was added. The reaction was carried out at 80℃~100℃ for 24 h~48 h. After the reaction was completed, the toluene solvent and unreacted raw materials were removed by vacuum distillation to obtain the anionic precursor. The molar ratio of phosphorus pentasulfide to alkylphenol was 1:3.3~4.

0. S3 Synthesis of Target Ionic Liquid: The cationic precursor and excess anhydrous ethanol solvent were added sequentially to container C. Then, the anionic precursor was rapidly added dropwise and stirred at room temperature for 24 h to 48 h. After the reaction, the ethanol solvent was removed by rotary evaporation, and then the mixture was dried under vacuum at 70 °C for 12 h to 24 h to obtain the target ionic liquid. The molar ratio of the cationic precursor to the anionic precursor was 1:0.98 to 1.

02.

3. The preparation method of the proton-type ionic liquid additive of thiophosphate ester as described in claim 2, characterized in that: In step S2, alkylphenol refers to C1~C60 phenols. 20 One of the alkylphenols.

4. The application of the thiophosphate proton-type ionic liquid additive as described in claim 1, characterized in that: This additive is used to prepare complex lithium-based grease.

5. The application of the thiophosphate proton-type ionic liquid additive as described in claim 4, characterized in that: The composite lithium-based grease is prepared by the following method: 12-hydroxystearic acid and azelaic acid are dissolved in 2 / 3 of the base oil at 60-80℃. Then, a lithium hydroxide aqueous solution with a mass concentration of 9%-11% is added to the solution, and the mixture is subjected to a saponification reaction at 60-80℃ for 2 hours. The mixture is then heated to 200-220℃ for high-temperature refining. After 5-10 minutes, the remaining 1 / 3 of the base oil is added, and the mixture is allowed to cool naturally to room temperature. The mixture is then milled three times using a three-roll mill to obtain the base grease. Then, 1-5% of the additives are added to the base grease, and the mixture is milled three times again using a three-roll mill to obtain a composite lithium-based grease containing additives. The mass ratio of azelaic acid, 12-hydroxystearic acid, base oil, and lithium hydroxide aqueous solution is 1:12.5-13.0:160-165:13-14.

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