A borate ionic liquid lubricant additive, its preparation method and application

Abstract

The present invention provides a borate ionic liquid lubricating additive, a preparation method thereof and an application thereof. The structural formula of the additive is: #imgabs0#R = —C n H 2n+1 , n = 4 to 18. The preparation method of the borate ionic liquid lubricating additive is as follows: the borate and lithium bis(trifluoromethanesulfonyl)imide are mixed in a molar ratio of 1:1, and stirred at 80°C to 120°C for 2 h to 4 h to obtain the additive. The borate ionic liquid lubricating additive of the present invention has excellent anti-wear and friction-reducing properties in lubricating greases.

Description

Technical Field

[0001] The present invention relates to a borate ionic liquid lubricating additive, its preparation and application, belonging to the field of lubrication technology. Background Art

[0002] Ionic liquids refer to salts that are liquid at room temperature or near room temperature and are composed entirely of cations and anions, also known as low-temperature molten salts. Ionic liquids have excellent properties such as low volatility, non-flammability, thermal stability, low melting point and good conductivity, and are ideal lubricating materials.

[0003] Organic borates have good anti-wear and friction-reducing properties, are non-toxic and easily degradable, and are a type of environmentally friendly lubricating oil additive with broad application prospects. The good lubricating properties of organic borates come from two aspects: on the one hand, boron atoms have empty 2p orbitals. When metal undergoes friction, free electrons in the metal will escape from the bondage of metal atoms and escape to the metal surface. These free electrons will enter the empty orbit of boron, making boron show a negative valence. The metal surface shows positive metal ions due to the loss of free electrons. The strong adsorption between boron anions and metal cations forms a dense adsorption film on the metal surface, thus separating the mutually contacting friction surfaces and reducing friction and wear. On the other hand, organic borates undergo tribochemical reactions on the metal surface during the friction process, forming an extreme pressure film containing boron oxide and iron oxide on the metal surface, thus playing a role in reducing friction and wear.

[0004] Coordination ionic liquids have the characteristics of simple preparation process, high atomic utilization rate, and green and pollution-free, and are an important type of ionic liquids. There are many studies on coordination ionic liquids as lubricating additives, which have excellent anti-wear and friction-reducing properties. For example, patents CN103160363B, CN103571566B, CN103571567B, and CN103865613B respectively prepared ionic liquids in situ with lithium salts (lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium trifluoromethanesulfonate) and ketones, urea, ethers (triglyme, tetraethylene glycol dimethyl ether, ether-substituted triazine, ether-substituted cyclotriphosphazene, ether-substituted benzotriazole), etc. The principle of the prepared coordination ionic liquids is that the anion groups in the lithium salts are relatively large, while the cation Li + is relatively small and free around the relatively large anion groups. The binding of the anion groups to Li + is relatively weak. Li + has an empty orbital with an acceptable electron pair and is easily attracted by the O atom when encountering an O atom with strong electronegativity, forming a coordination with oxygen to form a coordination ionic liquid. Summary of the Invention

[0005] The borate ionic liquid lubricating additive described in the present invention has a formation mechanism that also involves the O atom in the B-O-C bond and Li+ Coordination is formed through the interaction of

[0006] The object of the present invention is to provide a borate ionic liquid lubricating additive, a preparation method thereof and an application thereof, which solve the problems of poor stability and unsatisfactory anti-wear performance of borate additives in the prior art.

[0007] The present invention adopts the following technical solutions:

[0008] A borate ionic liquid lubricating additive described in the present invention has a structural formula of formula (1):

[0009]

[0010] R = —C n H 2n+1 , n = 4 to 18, and n is an integer. For example, n = 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18.

[0011] Furthermore, the additive is tributyl borate / bis(trifluoromethanesulfonyl)imide lithium ionic liquid or tris(octadecyl) borate / bis(trifluoromethanesulfonyl)imide lithium ionic liquid.

[0012] A preparation method of a borate ionic liquid lubricating additive as described above in the present invention, the preparation method of the borate ionic liquid lubricating additive includes the following steps:

[0013] Weigh equimolar amounts of borate and lithium bis(trifluoromethanesulfonyl)imide and add them to a single-necked flask, stir at 80°C to 100°C for 2h to 4h to obtain the product borate ionic liquid.

[0014] An application of a borate ionic liquid lubricating additive as described above in the present invention, this additive is used in a grease. Based on the mass of the grease, the dosage of the borate ionic liquid lubricating additive in the grease is 0.5wt% to 4wt%. For example, the dosage of the borate ionic liquid lubricating additive in the grease is 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt% or 4wt%.

[0015] The grease as described above is one of lithium-based grease and polyurea grease.

[0016] The technical features and beneficial effects of the present invention:

[0017] A borate ionic liquid lubricating additive according to the present invention. This borate ionic liquid has more excellent stability than borate, and has more excellent anti-wear and friction-reducing properties in grease. At the same time, the preparation method of the present invention is simple, the process route is green and environmentally friendly, the product yield is high, the atom economy is good, and no by-products are generated. Description of the Drawings

[0018] Figure 1 It is the thermogravimetric diagram of tributyl borate and tributyl borate / bis(trifluoromethanesulfonyl)imide lithium ionic liquid;

[0019] Figure 2 It is the thermogravimetric diagram of tris(octadecyl) borate and tris(octadecyl) borate / bis(trifluoromethanesulfonyl)imide lithium ionic liquid. Detailed Embodiments

[0020] The present invention will be further elaborated and explained below in conjunction with the drawings and specific embodiments.

[0021] Example 1

[0022] Weigh 4.60 g (0.02 mol) of tributyl borate and 5.74 g (0.02 mol) of lithium bis(trifluoromethanesulfonyl)imide and add them to a 25 ml single-necked flask. Stir and react at 80 °C for 4 h to obtain a colorless transparent liquid, which is the product tributyl borate / bis(trifluoromethanesulfonyl)imide lithium ionic liquid.

[0023] Example 2

[0024] Weigh 8.19 g (0.01 mol) of tris(octadecyl) borate and 2.87 g (0.01 mol) of lithium bis(trifluoromethanesulfonyl)imide and add them to a 25 ml single-necked flask. Stir and react at 120 °C for 2 h to obtain a pale yellow solid, which is the product tris(octadecyl) borate / bis(trifluoromethanesulfonyl)imide lithium ionic liquid.

[0025] The thermogravimetric properties of the prepared ionic liquid and borate are as Figure 1 and Figure 2 shown. The test conditions are: nitrogen protection, air purge at 80 ml / min, heating rate of 10 °C / min, 40 °C to 700 °C. According to Figure 1 and Figure 2 , it can be seen that the initial decomposition temperature of tributyl borate is 147.5 °C; the initial decomposition temperature of the ionic liquid in Example 1 is 172.2 °C; the initial decomposition temperature of tris(octadecyl) borate is 258.1 °C; the initial decomposition temperature of the ionic liquid in Example 2 is 329.6 °C; the thermal stability performance of borate after forming a coordination-type ionic liquid with lithium bis(trifluoromethanesulfonyl)imide has been improved.

[0026] The following are test examples to further illustrate the present invention. The test sample compositions of the test examples are shown in Table 1. The preparation method of the lithium-based grease is as follows: 87 wt% of PAO10 and 13 wt% of lithium 12-hydroxystearate are mixed and heated to 205 °C and held for 5 min, and then cooled to room temperature to obtain the lithium-based grease.

[0027] The preparation method of the polyurea grease is as follows: 85 wt% of diisooctyl sebacate and 15 wt% of polyurea raw materials (diphenylmethane-4,4'-diisocyanate, octadecylamine, cyclohexylamine are fed in a molar ratio of 1:0.8:1.2) are mixed and heated to 160 °C and held for 5 min, and then cooled to room temperature to obtain the polyurea grease; the polyurea grease is a base grease with a soap content of 15 wt%.

[0028] Table 1 Compositions of Test Examples and Comparative Examples

[0029]

[0030] Tribological Property Test

[0031] The test examples and comparative examples were subjected to tribological property tests, and the wear volumes were characterized and compared.

[0032] Test method: The test equipment is an SRV-V micro-tribo-wear tester from Optimol Oelwerke GmbH in Germany. The test conditions are a load of 100 N, a temperature of 100 °C, a frequency of 50 Hz, a stroke of 1 mm, and a time of 30 min. The steel balls used in the test are AISI 52100 bearing steel with a diameter of 10 mm, and the steel blocks used as the lower specimens are AISI 52100 bearing steel with a diameter of 24 mm and a height of 7.9 ± 0.1 mm. A MicroXAM3D non-contact three-dimensional surface profiler was used to characterize the wear amount of the lower specimen steel blocks after SRV testing.

[0033] The test results are shown in Table 2.

[0034] Table 2 Tribological Property Test Results of Test Examples 1 to 6, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4.

[0035] Test sample <![CDATA[Wear volume (×10 4 μm 3 )]]> Coefficient of friction Test Example 1 11.34 0.114 Test Example 2 9.68 0.098 Test Example 3 5.95 0.081 Test Example 4 6.44 0.086 Test Example 5 5.29 0.094 Comparative Example 1 75.72 0.156 Comparative Example 2 6.82 0.107 Test Example 6 9.5 0.093 Comparative Example 3 144.7 0.138 Comparative Example 4 34.7 0.129

[0036] As can be seen from Table 2, after adding 0.5 wt% - 4 wt% of the ionic liquid of Example 1 to the lithium-based grease, the wear volume is significantly reduced compared to the lithium-based grease. Among them, the lithium-based grease added with 2 wt% of the ionic liquid of Example 1 has a smaller wear volume and a lower friction coefficient than the lithium-based grease with 2 wt% of tributyl borate, showing a better anti-friction and anti-wear effect. After adding 2% of the ionic liquid of Example 2 to the polyurea grease, the wear volume is reduced by 93.7% compared to the base grease, and the friction coefficient is decreased by 32.6%, which is better than adding 2% of tristearyl borate. The prepared ionic liquid shows excellent anti-wear and anti-friction properties in both greases.

[0037] A borate ionic liquid lubricating additive of the present invention. This borate ionic liquid has more excellent stability than borate and more excellent anti-wear and anti-friction properties in lubricating grease. At the same time, the preparation method of the present invention is simple, the process route is green and environmentally friendly, the product yield is high, the atom economy is good, and no by-products are generated.

[0038] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A borate ionic liquid lubricating additive, characterized in that, The additive has a structural formula of formula (1): （1） R = —C n H 2n+1 , n = 4 to 18, n is an integer.

2. The application of the lubricating additive according to claim 1, characterized in that, The additive is used in the grease. Based on the mass of the grease, the addition amount of the additive is 0.5 wt% to 4 wt%.

3. According to the application of the lubricating additive according to claim 2, characterized in that, The grease is a lithium-based grease or a polyurea grease.

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