A dialkyldithiophosphoric acid ester compound, a preparation method thereof, and application thereof as a lubricating grease additive

Abstract

This invention discloses a dialkyl dithiophosphate ester compound, its preparation method, and its application as a lubricating grease additive. The invention involves mixing methacrylic acid, an amine catalyst, and dialkyl dithiophosphate, stirring at room temperature for 1-3 hours, then heating to 60℃-80℃ and stirring for 3-6 hours. After the reaction is complete, the solvent and unreacted methacrylic acid are removed by vacuum distillation to obtain the dialkyl dithiophosphate ester compound. This invention, starting from the polarity of the compound molecule, designs and prepares a novel compound with good anti-wear and extreme pressure properties, free of halogens and metals, making it environmentally friendly and economical. It is expected to find wide application as a lubricating grease additive in lubrication engineering and industrial fields.

Description

Technical Field

[0001] This invention belongs to the field of lubricant additive technology, and relates to a dialkyl dithiophosphate compound, its preparation method, and its application as a lubricant additive. Background Technology

[0002] Reducing friction and wear of the main friction pairs in mechanical equipment, lowering energy consumption, and reducing environmental pollution are three major challenges facing modern machinery design, manufacturing, and use, and lubricating grease plays a crucial role. Lubricating grease possesses advantages such as high pressure resistance, good buffering performance, minimal leakage, good sealing properties, and good viscosity-temperature characteristics, making it an indispensable lubricant. As an important component of lubricants, the role of additives cannot be ignored. Anti-wear and extreme pressure additives, due to their ability to improve the tribological properties of lubricating greases, increase load-bearing capacity, reduce frictional resistance, and reduce wear and scratches, have become a very important class of additives in the lubrication field.

[0003] Some commonly used compound-based anti-wear and extreme pressure additives, such as chlorine-containing extreme pressure anti-wear agents, sulfur-containing extreme pressure anti-wear agents, and metal salt extreme pressure anti-wear agents, readily act on metal surfaces due to the presence of polar groups in their molecular structure. Due to frictional heat, these groups readily undergo chemical reactions on the surfaces of the contacting friction pairs, thereby forming a friction film with extreme pressure anti-wear properties. However, these additives are prone to corrosion, have strong odors, and produce ash, limiting their application in high-performance greases. Therefore, developing novel high-performance extreme pressure anti-wear additives is of great significance.

[0004] Therefore, this patent starts from the molecular structure design of anti-wear and extreme pressure additives, prepares high temperature extreme pressure anti-wear additives, and explores their friction reduction and anti-wear performance and extreme pressure performance in composite lithium-based greases. Summary of the Invention

[0005] The present invention aims to provide a high-temperature extreme pressure anti-wear agent, a dialkyl dithiophosphate compound, and its preparation method, as an additive for lubricating greases. This invention, considering the harsh operating conditions of lubricating greases, develops a novel additive with excellent extreme pressure anti-wear properties at high temperatures. This type of additive can significantly improve key properties such as friction reduction, anti-wear, and extreme pressure in composite lithium-based lubricating greases, solving the technical problem of insufficient friction reduction, anti-wear, and extreme pressure performance of lubricating greases at high temperatures.

[0006] This invention relates to a high-temperature extreme pressure anti-wear agent, a dialkyl dithiophosphate compound, and its preparation method, comprising the following steps: (1) At room temperature, phosphorus pentasulfide was added to toluene solvent, and then alkylphenol was added. The mixture was stirred at 60℃-80℃ for 10-16 h. After the reaction was completed, the unreacted phosphorus pentasulfide was removed by hot filtration. The solvent and unreacted alkylphenol were removed by vacuum distillation at 90℃-110℃ to obtain dialkyl dithiophosphoric acid.

[0007] The alkylphenol is nonylphenol, dodecylphenol, or pentadecylphenol; the mass ratio of phosphorus pentasulfide to alkylphenol is 1:2 to 1:3.

[0008] (2) Mix methacrylic acid, amine catalyst and dialkyl dithiophosphate, stir at room temperature for 1-3 hours, then heat to 60℃-80℃ and stir for 3-6 hours. After the reaction is completed, remove the solvent and unreacted methacrylic acid by vacuum distillation at 90℃-130℃ to obtain the high temperature extreme pressure anti-wear additive dialkyl dithiophosphate ester compound.

[0009] Among them, the amine catalyst is triethylamine, tert-butylamine or diisooctylamine; the mass ratio of methacrylic acid and dialkyl dithiophosphoric acid is 1:1 to 1:2; the mass ratio of methacrylic acid and amine catalyst is 24:1 to 26:1.

[0010] The structural formula of dialkyl dithiophosphate compounds is: ; Wherein, R is n-nonyl, n-dodecyl, or n-pentadecanyl.

[0011] The dialkyl dithiophosphate compounds in this invention, as additives for composite lithium-based greases, can significantly reduce the friction coefficient and wear scar diameter of the base grease, exhibiting excellent friction reduction and anti-wear properties. They can also significantly increase the maximum non-seize load and sintering load of the base grease, exhibiting excellent extreme pressure properties, and can be used as extreme pressure additives for high-performance greases.

[0012] The beneficial effects of this invention are: 1. The high-temperature extreme pressure anti-wear additive, dialkyl dithiophosphate ester, has a novel structure and exhibits excellent friction reduction, anti-wear, and extreme pressure properties as an additive in composite lithium-based greases, thus solving the technical problem of insufficient friction reduction, anti-wear, and extreme pressure properties of greases at high temperatures.

[0013] 2. This invention starts with the polarity of compound molecules to design and prepare compounds with novel structures, good anti-wear and extreme pressure properties, and which do not contain halogens, metals, or other elements. They are environmentally friendly and economical, and are expected to be widely used as grease additives in lubrication engineering and industrial fields. Attached Figure Description

[0014] Figure 1 TPTP NMR results for dialkyl dithiophosphate compounds; Figure 2 DPTP NMR results for dialkyl dithiophosphate compounds; Figure 3 The results are HPTP NMR values ​​for dialkyl dithiophosphate compounds. Detailed Implementation

[0015] The present invention will be further explained and described below with reference to specific embodiments.

[0016] Example 1 At room temperature, 5 g of phosphorus pentasulfide was added to a flask containing 50 ml of toluene solvent, and a tail gas treatment device was connected. 16.52 g of n-nonylphenol was then added to the flask, and the mixture was stirred at 60 °C for 14 h. After the reaction, the unreacted phosphorus pentasulfide was removed by hot filtration, and the solvent and unreacted nonylphenol were removed by vacuum distillation at 110 °C to obtain dinonylphenol dithiophosphate. In a flask equipped with a condenser, 6.52 g of methacrylic acid, 0.26 g of triethylamine, and 14.01 g of dibutylphenol dithiophosphate were added, and the mixture was stirred at room temperature for 2.5 h, then heated to 75 °C and stirred for another 5 h. After the reaction, the solvent and unreacted methacrylic acid were removed by vacuum distillation at 110 °C to obtain dinonylphenol dithiophosphate, denoted as TPTP. The prepared compound was subjected to NMR analysis, and the results are as follows: Figure 1 As shown. By Figure 1 It can be seen that [DPTP] 1 H NMR (chloroform-d, 600 MHz) δ0.47-1.78 (m, 41H, -CH3-CH2), 2.62-3.39 (m, 3H, -CH2-CH), 6.82-7.34 (m, 8H, CH).

[0017] 10.88g of 12-hydroxystearic acid and 0.85g of azelaic acid were dissolved in 70.40g of base oil PAO40 at 80℃. Then, 1.92g of saturated lithium hydroxide aqueous solution was added, and the mixture was saponified at 80℃ for 1.5 h. The mixture was then heated to 220℃ and refined at high temperature for 5 min. 17.60g of 5750 lubricating oil (NYCOBASE 5750 lubricating oil from NYCO, France) was added. The mixture was allowed to cool naturally to room temperature and then ground three times using a three-roll mill to obtain a composite lithium-based grease, denoted as LCG.

[0018] Add 1g of TPTP to 99g of LCG, stir thoroughly, and then grind three times using a three-roll mill to obtain a grease composition containing 1% TPTP by mass, denoted as LCG+1% TPTP.

[0019] Example 2 The preparation process of TPTP is the same as in Example 1.

[0020] The preparation process of LCG is the same as in Example 1.

[0021] Add 2g of TPTP to 98g of LCG, stir thoroughly, and then grind three times using a three-roll mill to obtain a grease composition containing 2% TPTP by mass, denoted as LCG+2% TPTP.

[0022] Example 3 The preparation process of TPTP is the same as in Example 1.

[0023] The preparation process of LCG is the same as in Example 1.

[0024] Add 3g of TPTP to 97g of LCG, stir thoroughly, and then grind three times using a three-roll mill to obtain a grease composition containing 3% TPTP by mass, denoted as LCG+3% TPTP.

[0025] Example 4 At room temperature, 5 g of phosphorus pentasulfide was added to a flask containing 50 ml of toluene solvent, and a tail gas treatment device was connected. 19.68 g of n-dodecylphenol was then added to the flask, and the mixture was stirred at 80 °C for 16 h. After the reaction, the unreacted phosphorus pentasulfide was removed by hot filtration, and the solvent and unreacted n-dodecylphenol were removed by vacuum distillation at 110 °C to obtain di-n-dodecylphenol dithiophosphate. In a flask equipped with a condenser, 2.13 g of methacrylic acid, 0.18 g of tert-butylamine, and 16.98 g of di-n-dodecylphenol dithiophosphate were added, and the mixture was stirred at room temperature for 3 h, then heated to 80 °C and stirred for another 6 h. After the reaction, the solvent and unreacted methacrylic acid were removed by vacuum distillation at 120 °C to obtain di-n-dodecylphenol dithiophosphate, denoted as DPTP. The prepared compounds were subjected to NMR analysis, and the results are as follows: Figure 2 As shown. By Figure 2 It can be seen that [DPTP] 1 H NMR(chloroform-d, 600 MHz) δ 0.30-0.92(m,12H,-CH3),2.79-3.45(m,3H,-CH2,-CH),6.94-7.35(m,8H,-CH).

[0026] The preparation process of LCG is the same as in Example 1.

[0027] Add 1g of DPTP to 99g of LCG, stir thoroughly, and then grind three times using a three-roll mill to obtain a grease composition containing 1% DPTP by mass, denoted as LCG+1% DPTP.

[0028] Example 5 The preparation process of DPTP is the same as in Example 4.

[0029] The preparation process of LCG is the same as in Example 1.

[0030] Add 2g of DPTP to 98g of LCG, stir thoroughly, and then grind three times using a three-roll mill to obtain a grease composition containing 2% DPTP by mass, denoted as LCG+2% DPTP.

[0031] Example 6 The preparation process of DPTP is the same as in Example 4.

[0032] The preparation process of LCG is the same as in Example 1.

[0033] Add 3g of DPTP to 97g of LCG, stir thoroughly, and then grind three times using a three-roll mill to obtain a grease composition containing 3% DPTP by mass, denoted as LCG+3% DPTP.

[0034] Example 7 At room temperature, 5 g of phosphorus pentasulfide was added to a flask containing 50 ml of toluene solvent, and a tail gas treatment device was connected. 23.88 g of n-pentadecanylphenol was then added to the flask, and the mixture was stirred at 80 °C for 16 h. After the reaction, the unreacted phosphorus pentasulfide was removed by hot filtration, and the solvent and unreacted n-pentadecanylphenol were removed by vacuum distillation at 110 °C to obtain di-n-pentadecanylphenol dithiophosphate. In a flask equipped with a condenser, 2.13 g of methacrylic acid, 0.60 g of diisooctylamine, and 19.18 g of di-n-pentadecanylphenol dithiophosphate were added, and the mixture was stirred at room temperature for 3 h, then heated to 80 °C and stirred for another 6 h. After the reaction, the solvent and unreacted methacrylic acid were removed by vacuum distillation at 130 °C to obtain di-n-pentadecanylphenol dithiophosphate, denoted as HPTP. NMR analysis of the prepared compounds was performed, and the results are as follows: Figure 3 As shown. By Figure 3 It can be seen that [HPTP] 1H NMR (chloroform-d, 600 MHz) δ 0.80(t, 6H, -CH3), 1.24 (s, 56H, -CH2), 1.57 (s, 3H, -CH3), 2.44-2.54 (m, 2H, -CH2), 3.02 (s, 1H, -CH), 6.88-7.21 (m, 8H, -CH).

[0035] The preparation process of LCG is the same as in Example 1.

[0036] Add 1g of HPTP to 99g of LCG, stir thoroughly, and then grind three times using a three-roll mill to obtain a grease composition containing 1% HPTP by mass, denoted as LCG+1% HPTP.

[0037] Example 8 The preparation process of HPTP is the same as in Example 7.

[0038] The preparation process of LCG is the same as in Example 1.

[0039] Add 2g of HPTP to 98g of LCG, stir thoroughly, and then grind three times using a three-roll mill to obtain a grease composition containing 2% HPTP by mass, denoted as LCG+2% HPTP.

[0040] Example 9 The preparation process of HPTP is as described in Example 7.

[0041] The preparation process of LCG is as described in Example 1.

[0042] Add 3g of HPTP to 97g of LCG, stir thoroughly, and then grind three times using a three-roll mill to obtain a grease composition containing 3% HPTP by mass, denoted as LCG+3% HPTP.

[0043] Comparative Example The preparation process of LCG is the same as in Example 1. No additives were added to the LCG.

[0044] Tribological performance testing: Taking TPTP1 prepared in Example 1 of this invention as an example, its high-temperature friction reduction and anti-wear performance as a composite lithium-based grease additive was investigated using a four-ball friction and wear tester, and compared with LCG base grease in the comparative example.

[0045] The test conditions were as follows: load 392 N, temperature: room temperature, 75℃, 150℃, rotation speed 1200 r / min, test time 60 min. The steel balls used in the test were all GCr15 bearing steel, with a diameter of 12.7 mm and a hardness of HRC 60-63. The coefficient of friction (f) was recorded during the test. After the friction test, the wear scar diameter (WSD) of the steel balls was measured using an optical microscope. The tribological property test results are shown in Table 1.

[0046] As shown in Table 1 based on the tribological performance test results, the high-temperature extreme pressure anti-wear agent in this invention, as an additive for composite lithium-based grease, can significantly reduce the friction coefficient and wear scar diameter of the base grease under room temperature, 75°C and high temperature (150°C) conditions, exhibiting excellent friction reduction and anti-wear performance, and can be used as a high-performance high-temperature friction reduction and anti-wear additive for grease.

[0047] Extreme pressure performance test: Taking the TPTP prepared in Example 1 of this invention as an example, its extreme pressure performance as a composite lithium-based grease additive was investigated on an extreme pressure four-ball testing machine and compared with the LCG base grease in the comparative example.

[0048] The test conditions were: rotational speed 1770 r / min, test time 10 s, room temperature, gradually increasing load. The steel balls used in the test were all GCr15 bearing steel, with physical parameters of: diameter 12.7 mm, hardness HRC 60-63. The maximum non-seizure load (P) was recorded during the test. B ) and sintering load (P D The extreme pressure performance test results are shown in Table 2.

[0049] As shown in Table 2 based on the extreme pressure performance test results, the high-temperature extreme pressure anti-wear agent in this invention, as an additive for composite lithium-based grease, can significantly improve the maximum non-seize load and sintering load of the base grease, exhibiting excellent extreme pressure performance, and can be used as a high-performance grease extreme pressure additive.

[0050] The above description is only one of two embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dialkyl dithiophosphate compound with the following structural formula: in, R is n-nonyl, n-dodecyl, or n-pentadecanyl.

2. The method for preparing the dialkyl dithiophosphate compound as described in claim 1, comprising the following steps: (1) Phosphorus pentasulfide was added to toluene solvent at room temperature, followed by alkylphenol. The mixture was stirred at 60℃-80℃ for 10-16 h. After the reaction was completed, the unreacted phosphorus pentasulfide was removed by hot filtration. The solvent and unreacted alkylphenol were removed by vacuum distillation to obtain dialkyl dithiophosphate. The alkylphenol was nonylphenol, dodecylphenol, or pentadecylphenol. The mass ratio of phosphorus pentasulfide to alkylphenol was 1:2 to 1:

3. (2) Mix methacrylic acid, amine catalyst and dialkyl dithiophosphate, stir at room temperature for 1-3 hours, then heat to 60℃-80℃ and stir for 3-6 hours. After the reaction is complete, remove the solvent and unreacted methacrylic acid by vacuum distillation to obtain dialkyl dithiophosphate ester compounds. The amine catalyst is triethylamine, tert-butylamine or diisooctylamine. The mass ratio of methacrylic acid to dialkyl dithiophosphate is 1:1 to 1:

2. The mass ratio of methacrylic acid to amine catalyst is 24:1 to 26:

1.

3. The application of the dialkyl dithiophosphate compound as described in claim 1 as an additive in lubricating grease, characterized in that: The grease is a complex lithium-based grease. The preparation method of the complex lithium-based grease is as follows: 12-hydroxystearic acid and azelaic acid are dissolved in 4 / 5 of the total mass of base oil at 60-80℃. Then, a saturated lithium hydroxide aqueous solution is added, and a saponification reaction is carried out at 60-80℃ for 1-3 hours. The mixture is then heated to 200-220℃ for high-temperature refining for 5-10 minutes. Finally, 1 / 5 of the total mass of base oil is added, and the mixture is allowed to cool naturally to room temperature. It is then ground using a three-roll mill to obtain the complex lithium-based grease. The mass ratio of 12-hydroxystearic acid to azelaic acid is 10:1~15:1; the mass ratio of azelaic acid to the saturated lithium hydroxide aqueous solution is 1:2~1:3.

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