High-performance low-temperature lubricant and preparation method thereof

Abstract

The invention relates to the technical field of lubricants, and discloses a high-performance low-temperature lubricant and a preparation method thereof.The high-performance low-temperature lubricant is prepared from, by weight, 75-85 parts of base oil, 8-12 parts of a composite surfactant, 4-7 parts of an extreme pressure lubricant, 1-3 parts of an antioxidant and 0.5-2.5 parts of a fluoborate wear-resistant pour point depressant; wherein the fluoborate wear-resistant pour point depressant contains long-chain alkyl in the shape of a pour point depressant, after the fluoborate wear-resistant pour point depressant is added into the base oil, the side-chain alkyl of the fluoborate wear-resistant pour point depressant is co-crystallized with wax, and a polar main chain is left outside a crystal to play a shielding role, so that the flow resistance of the lubricant is reduced, and a pour point depressing role is played; under the friction condition, the fluoborate in the structure can chemically react with metal elements in mechanical equipment to generate fluoride and boron-containing compounds with high hardness and wear resistance, so that the friction coefficient is reduced, and meanwhile, the quaternary ammonium salt has excellent corrosion resistance; the lubricant prepared by the invention can meet the normal operation requirement of equipment in a low-temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricants, and in particular to a high-performance low-temperature lubricant and a preparation method thereof. Background Art

[0002] Lubricants are widely used in industries such as machining, transportation, metallurgy, coal, and construction. They can act on various types of machinery to reduce friction and at the same time have functions such as cooling, sealing, anti-corrosion, and insulation for mechanical equipment. Currently, lubricants on the market can meet the usage requirements under normal temperature environments. However, in many fields such as aerospace, military, chemical industry, and manufacturing, equipment often needs to operate in harsh outdoor environments in alpine regions. Ordinary lubricants will have a deteriorated fluidity and a decreased lubricating performance at low temperatures, and then there will be phenomena such as tightness or seizure, resulting in difficulties in disassembling equipment parts and being unable to meet the normal operation requirements of these equipment in low-temperature environments. Therefore, there is an urgent need for a high-performance lubricant with low-temperature resistance and abrasion resistance.

[0003] Currently, there are some low-temperature lubricants on the market, such as HV and HS low-temperature lubricants. The HV low-temperature lubricant is mainly used in medium-pressure or high-pressure hydraulic systems of construction machinery, imported equipment, and vehicles in cold regions or with a large temperature change range and harsh working conditions. However, its abrasion resistance is poor and it cannot meet the lubrication requirements of these components during long-term operation at extremely low temperatures, resulting in increased component wear and affecting the normal operation and service life of the equipment. The HS low-temperature lubricant is mainly used for the above-mentioned various equipment in extremely cold regions. However, the adaptability of this lubricant to the environment is not wide enough, and its performance may be greatly affected under certain special environmental conditions, such as high humidity and strong corrosive environments. In addition, the durability of some lubricants is also a key issue. During long-term use, lubricants are easily affected by external factors and their performance deteriorates, requiring frequent replacement, which increases the maintenance cost and downtime of the equipment. At the same time, the anti-emulsification property, rust prevention property, oxidation stability, hydrolysis stability, and thermal stability of the lubricants also need to be improved.

[0004] Most of the currently widely used lubricants use mineral oil as the base oil. However, due to its poor biodegradability and biological toxicity, mineral oil lubricants pose a great hazard to water bodies, soil, and even groundwater, seriously affecting the environment. Vegetable oil is a renewable resource. It not only has advantages such as non-toxicity and high biodegradability but also has advantages such as high flash point and low evaporation loss, and has the potential to replace mineral oil-based lubricants. However, the poor low-temperature fluidity of vegetable oil limits its further development. Therefore, it is of great practical significance to develop a high-performance, simple preparation process, low-cost, and biodegradable low-temperature lubricant. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies existing in the prior art, and provides a high-performance low-temperature lubricant and its preparation method, which solves the problems that the existing lubricants will have poor fluidity and reduced lubrication performance at low temperatures, so as to meet the normal operation requirements of equipment in a low-temperature environment.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: A high-performance low-temperature lubricant comprises the following components in parts by weight: 75 - 85 parts of base oil, 8 - 12 parts of composite surfactant, 4 - 7 parts of extreme pressure lubricant, 1 - 3 parts of antioxidant, and 0.5 - 2.5 parts of fluoroborate wear-resistant pour point depressant; the preparation method is: under the condition that the stirring speed is 2500 - 3000 r / min, the base oil, composite surfactant, extreme pressure lubricant and antioxidant are sequentially added into a beaker, heated to 80 - 90 °C and mixed evenly, then an aqueous sodium chloride solution with a mass fraction of 20 - 30% is added, and stirring is continued for 20 - 40 min. Finally, the fluoroborate wear-resistant pour point depressant is added and stirred for 1 - 3 h to obtain the high-performance low-temperature lubricant.

[0007] The base oil is a compound of modified waste cooking oil and white oil in a mass ratio of 2:1.

[0008] The composite surfactant is a compound of OP-10, SP-80 and TW-80 in a mass ratio of 1:1:1.

[0009] Furthermore, the preparation method of the modified vegetable oil is: add 10 g of waste cooking oil and 50 mL of isopropanol into a reaction flask, stir evenly, then add 0.3 - 0.5 g of sodium hydroxide and 4 - 6 g of triethanolamine, react at 70 - 85 °C for 5 - 8 h. After the reaction is completed, cool to room temperature and layer. The upper layer product is washed with saturated brine, separated and dried to obtain the modified waste cooking oil.

[0010] Furthermore, the extreme pressure lubricant is prepared by dehydrating pentaerythritol and lauric diacid at a molar ratio of 4:1 at 180 °C.

[0011] Furthermore, the preparation method of the fluoroborate wear-resistant pour point depressant is as follows: Step (1): Under a nitrogen atmosphere, add 2-(bromomethyl)naphthalene and acetonitrile into a reaction flask, stir evenly, then add N-methyldiallylamine, stir and react. After the reaction is completed, cool to room temperature, precipitate, filter, and dry to obtain an alkenyl naphthalene bromoquaternary ammonium salt intermediate.

[0012] Step (2): Add the alkenyl naphthalene bromoquaternary ammonium salt intermediate and ethanol into a reaction flask, stir evenly, then dropwise add tetrafluoroboric acid with a mass fraction of 35 - 45%, stir and react. After the reaction is completed, concentrate, dissolve in ethanol and recrystallize, wash with petroleum ether, and dry to obtain an alkenyl naphthalene tetrafluoroborate quaternary ammonium salt.

[0013] Step (3): Under a nitrogen atmosphere, add 100 parts of castor oil, 10 - 15 parts of maleic anhydride and toluene by weight to the reaction flask. After stirring evenly at 45 - 55°C, add 20 - 30 parts of quaternary ammonium salt of alkenylnaphthalene tetrafluoroborate and 2 - 5 parts of initiator, and react at 85 - 100°C for 5 - 12 h. After sedimentation, drying, and purification, a tetrafluoroborate wear-resistant pour point depressant is obtained.

[0014] Furthermore, in step (1), the mass ratio of 2-(bromomethyl)naphthalene to N-methyldiallylamine is 100:50 - 60.

[0015] Furthermore, in step (1), the reaction temperature is 65 - 80°C and the reaction time is 12 - 24 h.

[0016] Furthermore, in step (2), the ratio of the alkenylnaphthalene bromoquaternary ammonium salt intermediate to tetrafluoroboric acid is 100:65 - 90.

[0017] Furthermore, in step (2), the reaction temperature is 75 - 90°C and the reaction time is 3 - 8 h.

[0018] Furthermore, in step (3), the initiator is any one of azobisisobutyronitrile, dimethyl azobisisobutyrate, or benzoyl peroxide.

[0019] Adopting the above technical solutions, the beneficial effects of the present invention are as follows: (1) It has a relatively low pour point: The tetrafluoroborate wear-resistant pour point depressant contains a polymer composed of a pour point depressant long-chain alkyl group and a polar group. After adding it to the base oil, its side-chain alkyl group co-crystallizes with wax, and the polar main chain remains outside the crystal to play a shielding role. It co-crystallizes with the surface of the wax crystal to have a directional effect on the growth of the crystal. In addition, the polar groups or main chain segments remaining on the surface of the wax crystal can also prevent the adhesion between crystals, increase the flow space of the base oil, reduce the flow resistance of the lubricant, and further play a role in depressing the pour point.

[0020] (2) Good friction reduction and anti-wear properties: Under friction conditions, the tetrafluoroborate wear-resistant pour point depressant can chemically react with metal elements in mechanical equipment to generate fluorides and boron-containing compounds with high hardness and wear resistance, forming an effective boundary lubricating film, making the metal surface smooth and flat, effectively hindering the catalytic effect of metal on oxidation, reducing the corrosion of corrosive substances on the metal surface, thereby reducing the friction coefficient. At the same time, the quaternary ammonium salt in the tetrafluoroborate wear-resistant pour point depressant can improve the viscosity and film-forming ability of the lubricant, form a stable lubricating film, reduce the friction and wear on the metal surface, effectively prevent the intrusion of external abrasive particles, and reduce wear.

[0021] (3) Excellent anti-corrosion performance: The quaternary ammonium cations in the fluoroborate wear-resistant pour point depressant can be adsorbed on the metal surface through electrostatic interaction to form a monomolecular adsorption film. At the same time, structures such as naphthalene rings in the molecule have steric hindrance and hydrophobicity, which can improve the density of the adsorption film, effectively isolate the contact between water or other corrosive substances and the metal, and further enhance the anti-corrosion effect. Detailed implementation mode

[0022] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description progresses. However, these embodiments are exemplary only and do not constitute any limitation to the scope of the present invention. Those skilled in the art should understand that the details and forms of the technical solutions of the present invention can be modified or replaced without departing from the spirit and scope of the present invention, but such modifications and replacements all fall within the protection scope of the present invention. Unless otherwise specified, the raw materials and reagents used in this application are all commercially available products or can be prepared by known methods.

[0023] 2-(Bromomethyl)naphthalene, CAS No. 939-26-4.

[0024] N-Methyldiallylamine, CAS No. 2424-01-3.

[0025] Castor oil, refined grade, Guangzhou Runquan Chemical Co., Ltd.

[0026] White oil, chemically pure, Chengdu Kelong Co., Ltd.

[0027] Example 1 (1) Under a nitrogen atmosphere, add 40 g of 2-(bromomethyl)naphthalene and 160 mL of acetonitrile to a reaction flask. After stirring evenly, add 22 g of N-methyldiallylamine and react at 75 °C for 16 h. Cool to room temperature, precipitate, filter, and dry to obtain an alkenyl naphthalene bromoquaternary ammonium salt intermediate. The preparation reaction formula is as follows:

[0028] (2) Add 30 g of the alkenyl naphthalene bromoquaternary ammonium salt intermediate and 240 mL of ethanol to the reaction flask. After stirring evenly, dropwise add 22.5 g of 40% tetrafluoroboric acid and react at 85 °C for 6 h. Concentrate, dissolve in ethanol and recrystallize, wash with petroleum ether, and dry to obtain an alkenyl naphthalene tetrafluoroborate quaternary ammonium salt. The preparation reaction formula is as follows:

[0029] (3) Under a nitrogen atmosphere, 100 g of castor oil, 12 g of maleic anhydride, and 200 mL of toluene were added to a reaction flask. After stirring evenly at 50 °C, 20 g of quaternary ammonium salt of vinylnaphthalene tetrafluoroborate and 3 g of azobisisobutyronitrile were added, and the reaction was carried out at 95 °C for 10 h. After sedimentation, drying, and purification, a fluoroborate wear-resistant pour point depressant was obtained.

[0030] (4) 100 g of waste oil and 500 mL of isopropanol were added to a reaction flask. After stirring evenly, 4 g of sodium hydroxide and 50 g of triethanolamine were added, and the reaction was carried out at 80 °C for 7 h. After the reaction ended, it was cooled to room temperature and layered. The upper product was washed with saturated brine, separated, and dried to obtain modified waste oil.

[0031] (5) Under the condition of a stirring speed of 2800 r / min, 80 g of base oil (the mass ratio of modified waste oil to white oil is 2:1), 10 g of composite surfactant (the mass ratio of OP-10, SP-80, and TW-80 is 1:1:1), 6 g of extreme pressure lubricant (prepared by dehydrating pentaerythritol and lauric diacid at a molar ratio of 4:1 at 180 °C), and 2 g of antioxidant BHT were successively added to a beaker, heated to 85 °C and mixed evenly, 7 g of 25% sodium chloride aqueous solution was added, and stirring was continued for 30 min. Finally, 0.5 g of fluoroborate wear-resistant pour point depressant was added and stirred for 2 h to obtain a high-performance low-temperature lubricant.

[0032] Example 2 (1) Under a nitrogen atmosphere, 120 g of 2-(bromomethyl)naphthalene and 360 mL of acetonitrile were added to a reaction flask. After stirring evenly, 60 g of N-methyldiallylamine was added, and the reaction was carried out at 80 °C for 12 h. After cooling to room temperature, a precipitate was formed, filtered, and dried to obtain an intermediate of quaternary ammonium salt of vinylnaphthalene bromide.

[0033] (2) 105 g of the intermediate of quaternary ammonium salt of vinylnaphthalene bromide and 630 mL of ethanol were added to a reaction flask. After stirring evenly, 68.25 g of 45% tetrafluoroboric acid was added dropwise, and the reaction was carried out at 90 °C for 3 h. It was concentrated, dissolved in ethanol and recrystallized, washed with petroleum ether, and dried to obtain quaternary ammonium salt of vinylnaphthalene tetrafluoroborate.

[0034] (3) Under a nitrogen atmosphere, 100 g of castor oil, 10 g of maleic anhydride, and 200 mL of toluene were added to a reaction flask. After stirring evenly at 55 °C, 23 g of quaternary ammonium salt of vinylnaphthalene tetrafluoroborate and 2 g of dimethyl azobisisobutyrate were added, and the reaction was carried out at 100 °C for 5 h. After sedimentation, drying, and purification, a fluoroborate wear-resistant pour point depressant was obtained.

[0035] (4) Add 100 g of waste cooking oil and 500 mL of isopropanol to a reaction flask. After stirring evenly, add 3 g of sodium hydroxide and 40 g of triethanolamine, and react at 85 °C for 5 h. After the reaction is completed, cool to room temperature and separate the layers. Wash the upper layer product with saturated brine, and obtain modified waste cooking oil after liquid separation and drying.

[0036] (5) Under the condition of a stirring speed of 3000 r / min, add 75 g of base oil (the mass ratio of modified waste cooking oil to white oil is 2:1), 12 g of compound surfactant (the mass ratio of OP-10, SP-80 and TW-80 is 1:1:1), 7 g of extreme pressure lubricant (prepared by dehydrating pentaerythritol and lauric diacid at a molar ratio of 4:1 at 180 °C) and 1 g of antioxidant BHT into a beaker in sequence. Heat to 90 °C and mix evenly, add 5 g of 30% sodium chloride aqueous solution by mass, continue to stir for 40 min, and finally add 1 g of fluoroborate wear-resistant pour point depressant and stir for 1 h to obtain a high-performance low-temperature lubricant.

[0037] Example 3 (1) Under a nitrogen atmosphere, add 20 g of 2-(bromomethyl)naphthalene and 100 mL of acetonitrile to a reaction flask. After stirring evenly, add 12 g of N-methyldiallylamine, and react at 65 °C for 24 h. Cool to room temperature, precipitate, filter, and obtain an alkenyl naphthalene bromide quaternary ammonium salt intermediate after drying.

[0038] (2) Add 15 g of alkenyl naphthalene bromide quaternary ammonium salt intermediate and 150 mL of ethanol to a reaction flask. After stirring evenly, dropwise add 13.5 g of 35% tetrafluoroboric acid by mass, and react at 75 °C for 8 h. Concentrate, dissolve in ethanol and recrystallize, wash with petroleum ether, and obtain an alkenyl naphthalene tetrafluoroborate quaternary ammonium salt after drying.

[0039] (3) Under a nitrogen atmosphere, add 100 g of castor oil, 15 g of maleic anhydride and 200 mL of toluene to a reaction flask. After stirring evenly at 45 °C, add 25 g of alkenyl naphthalene tetrafluoroborate quaternary ammonium salt and 5 g of benzoyl peroxide, and react at 85 °C for 12 h. After sedimentation, drying and purification, obtain a fluoroborate wear-resistant pour point depressant.

[0040] (4) Add 100 g of waste cooking oil and 500 mL of isopropanol to a reaction flask. After stirring evenly, add 5 g of sodium hydroxide and 60 g of triethanolamine, and react at 70 °C for 8 h. After the reaction is completed, cool to room temperature and separate the layers. Wash the upper layer product with saturated brine, and obtain modified waste cooking oil after liquid separation and drying.

[0041] (5) Under the condition that the stirring speed is 2500 r / min, 85 g of base oil (the mass ratio of modified gutter oil to white oil is 2:1), 8 g of composite surfactant (the mass ratio of OP-10, SP-80 and TW-80 is 1:1:1), 4 g of extreme pressure lubricant (prepared by dehydrating pentaerythritol and lauric diacid at a molar ratio of 4:1 at 180 °C), and 3 g of antioxidant BHT were successively added to a beaker, heated to 80 °C and mixed evenly, 8 g of 20% sodium chloride aqueous solution was added, stirred continuously for 40 min, and finally 1.5 g of fluoroborate wear-resistant pour point depressant was added and stirred for 3 h to obtain a high-performance low-temperature lubricant.

[0042] Example 4 (1) Under a nitrogen atmosphere, 65 g of 2-(bromomethyl)naphthalene and 250 mL of acetonitrile were added to a reaction flask. After stirring evenly, 36.5 g of N-methyldiallylamine was added, and the reaction was carried out at 70 °C for 18 h. After cooling to room temperature, a precipitate was formed, filtered, and dried to obtain an alkenyl naphthalene bromoquaternary ammonium salt intermediate.

[0043] (2) 50 g of alkenyl naphthalene bromoquaternary ammonium salt intermediate and 430 mL of ethanol were added to a reaction flask. After stirring evenly, 41 g of 40% tetrafluoroboric acid was added dropwise, and the reaction was carried out at 80 °C for 5 h. It was concentrated, dissolved in ethanol and recrystallized, washed with petroleum ether, and dried to obtain an alkenyl naphthalene tetrafluoroborate quaternary ammonium salt.

[0044] (3) Under a nitrogen atmosphere, 100 g of castor oil, 13 g of maleic anhydride and 200 mL of toluene were added to a reaction flask. After stirring evenly at 50 °C, 27 g of alkenyl naphthalene tetrafluoroborate quaternary ammonium salt and 4 g of azobisisobutyronitrile were added, and the reaction was carried out at 95 °C for 10 h. After sedimentation, drying and purification, a fluoroborate wear-resistant pour point depressant was obtained.

[0045] (4) 100 g of gutter oil and 500 mL of isopropanol were added to a reaction flask. After stirring evenly, 4.5 g of sodium hydroxide and 55 g of triethanolamine were added, and the reaction was carried out at 80 °C for 6 h. After the reaction, it was cooled to room temperature and layered. The upper product was washed with saturated brine, separated and dried to obtain modified gutter oil.

[0046] (5) Under the condition that the stirring speed is 2800 r / min, 78 g of base oil (the mass ratio of modified gutter oil to white oil is 2:1), 12 g of composite surfactant (the mass ratio of OP-10, SP-80 and TW-80 is 1:1:1), 6 g of extreme pressure lubricant (prepared by dehydrating pentaerythritol and lauric diacid at a molar ratio of 4:1 at 180 °C), and 2 g of antioxidant BHT were successively added to a beaker, heated to 90 °C and mixed evenly, 6 g of 30% sodium chloride aqueous solution was added, stirred continuously for 35 min, and finally 2 g of fluoroborate wear-resistant pour point depressant was added and stirred for 3 h to obtain a high-performance low-temperature lubricant.

[0047] Example 5 (1)Under a nitrogen atmosphere, 10 g of 2-(bromomethyl)naphthalene and 45 mL of acetonitrile were added to a reaction flask. After stirring evenly, 5.2 g of N-methyldiallylamine was added, and the reaction was carried out at 75 °C for 24 h. After cooling to room temperature, a precipitate was formed, filtered, and dried to obtain an alkenylnaphthalene bromoquaternary ammonium salt intermediate.

[0048] (2)8 g of the alkenylnaphthalene bromoquaternary ammonium salt intermediate and 68 mL of ethanol were added to a reaction flask. After stirring evenly, 6 g of 42% tetrafluoroboric acid by mass fraction was added dropwise, and the reaction was carried out at 85 °C for 7 h. It was concentrated, dissolved in ethanol and recrystallized, washed with petroleum ether, and dried to obtain an alkenylnaphthalene tetrafluoroborate quaternary ammonium salt.

[0049] (3)Under a nitrogen atmosphere, 100 g of castor oil, 14 g of maleic anhydride and 200 mL of toluene were added to a reaction flask. After stirring evenly at 55 °C, 30 g of the alkenylnaphthalene tetrafluoroborate quaternary ammonium salt and 5 g of dimethyl 2,2'-azobis(2-methylpropionate) were added, and the reaction was carried out at 90 °C for 9 h. After sedimentation, drying, and purification, a fluoroborate wear-resistant pour point depressant was obtained.

[0050] (4)100 g of waste oil and 500 mL of isopropanol were added to a reaction flask. After stirring evenly, 4.5 g of sodium hydroxide and 52 g of triethanolamine were added, and the reaction was carried out at 780 °C for 8 h. After the reaction was completed, it was cooled to room temperature and layered. The upper product was washed with saturated brine, separated and dried to obtain modified waste oil.

[0051] (5)Under the condition of a stirring speed of 3000 r / min, 82 g of base oil (the mass ratio of modified waste oil to white oil is 2:1), 8 g of composite surfactant (the mass ratio of OP-10, SP-80 and TW-80 is 1:1:1), 5 g of extreme pressure lubricant (prepared by dehydrating pentaerythritol and dodecanedioic acid at a molar ratio of 4:1 at 180 °C), and 2 g of antioxidant BHT were successively added to a beaker, heated to 90 °C and mixed evenly. 8 g of 25% sodium chloride aqueous solution was added, and stirring was continued for 25 min. Finally, 2.5 g of the fluoroborate wear-resistant pour point depressant was added and stirred for 3 h to obtain a high-performance low-temperature lubricant.

[0052] Comparative Example 1 (1)Under a nitrogen atmosphere, 100 g of castor oil, 12 g of maleic anhydride and 200 mL of toluene were added to a reaction flask. After stirring evenly at 50 °C, 20 g of the alkenylnaphthalene bromoquaternary ammonium salt intermediate (prepared in Example 1) and 3 g of azodiisobutyronitrile were added, and the reaction was carried out at 95 °C for 10 h. After sedimentation, drying, and purification, a modified additive was obtained.

[0053] (2) Under the condition that the stirring speed is 2800 r / min, 80 g of base oil (the mass ratio of modified waste cooking oil to white oil is 2:1), 10 g of composite surfactant (the mass ratio of OP-10, SP-80 and TW-80 is 1:1:1), 6 g of extreme pressure lubricant (prepared by dehydrating pentaerythritol and lauric diacid at a molar ratio of 4:1 at 180 °C), and 2 g of antioxidant BHT are successively added to a beaker, heated to 85 °C and mixed evenly, 7 g of 25% sodium chloride aqueous solution is added, and stirring is continued for 30 min. Finally, 0.5 g of modified additive is added and stirred for 2 h to obtain a lubricant.

[0054] Comparative Example 2 (1) Under a nitrogen atmosphere, 100 g of castor oil, 12 g of maleic anhydride and 200 mL of toluene are added to a reaction flask. After stirring evenly at 50 °C, 20 g of styrene and 3 g of azobisisobutyronitrile are added, and the reaction is carried out at 95 °C for 10 h. After sedimentation, drying and purification, a modified additive is obtained.

[0055] (2) Under the condition that the stirring speed is 2800 r / min, 80 g of base oil (the mass ratio of modified waste cooking oil to white oil is 2:1), 10 g of composite surfactant (the mass ratio of OP-10, SP-80 and TW-80 is 1:1:1), 6 g of extreme pressure lubricant (prepared by dehydrating pentaerythritol and lauric diacid at a molar ratio of 4:1 at 180 °C), and 2 g of antioxidant BHT are successively added to a beaker, heated to 85 °C and mixed evenly, 7 g of 25% sodium chloride aqueous solution is added, and stirring is continued for 30 min. Finally, 0.5 g of modified additive is added and stirred for 2 h to obtain a lubricant.

[0056] Comparative Example 3 Under the condition that the stirring speed is 2800 r / min, 80 g of base oil (the mass ratio of waste cooking oil to white oil is 2:1), 10 g of composite surfactant (the mass ratio of OP-10, SP-80 and TW-80 is 1:1:1), 6 g of extreme pressure lubricant (prepared by dehydrating pentaerythritol and lauric diacid at a molar ratio of 4:1 at 180 °C), and 2 g of antioxidant BHT are successively added to a beaker, heated to 85 °C and mixed evenly, 7 g of 25% sodium chloride aqueous solution is added, and stirring is continued for 30 min to obtain a lubricant.

[0057] Pour point test: Refer to GB / T 510-2018 "Determination Method for Pour Point of Petroleum Products" to determine the pour point of the lubricant. The prepared lubricant sample is filled into a test tube, sleeved with a casing and immersed in a cooling medium. After cooling to a certain temperature, the test tube is tilted 45°. After 1 min, observe whether the liquid level moves. If the liquid level does not move at this temperature and starts to move again when the temperature rises by 2 °C, record the temperature when the liquid level stops moving as the pour point of the lubricant.

[0058] Table 1 Pour Point Test of Lubricant The reason why lubricants are prone to solidify at low temperatures is that there are paraffin substances in the base oil. At low temperatures, high-melting-point paraffin molecules are arranged in an orderly manner, precipitating in the form of needle-like or flaky crystals and cross-linking with each other to form a three-dimensional network structure, and the low-melting-point oil is adsorbed or solvated and wrapped in the tight crystal voids, resulting in the loss of fluidity of the entire oil product. The lower the pour point, the less likely the lubricant is to solidify at low temperatures, and lubricants with a low pour point have a wider application range and are more suitable for some harsh working conditions. From the test results in the above table, it can be seen that as the content of the fluoroborate wear-resistant pour point depressant increases, the pour point of the lubricant gradually decreases, and the lowest can reach -25°C. This is because the fluoroborate wear-resistant pour point depressant contains a polymer composed of a pour point depressant long-chain alkyl group and a polar group. After adding it to the base oil, its side-chain alkyl group eutectifies with the wax, and the polar main chain remains outside the crystal to play a shielding role, eutectifying with the wax on the surface of the wax crystal and having a directional effect on the growth of the crystal. In addition, the polar groups or main chain segments remaining on the surface of the wax crystal can also prevent the adhesion between crystals, increasing the flow space of the base oil, reducing the flow resistance of the lubricant, and further playing a role in depressing the pour point. In Comparative Example 3, there is no fluoroborate wear-resistant pour point depressant, and it does not have a pour point depressing effect. Its pour point is relatively high and it is not suitable for use at low temperatures.

[0059] Wear Resistance Test: The wear resistance of the prepared lubricant was tested using a high-speed reciprocating ball-on-disk contact friction and wear testing machine. In the test, a steel ball with a diameter of 10 mm and a hardness of 700 HV was used, and the bottom plate was a steel block with a hardness of 600 HV. The steel block was polished before the experiment and ultrasonically cleaned with acetone for 10 min. The lubricants of the examples and comparative examples were applied between the friction pairs, with 0.1 g applied each time. The wear scar diameter was measured using an optical microscope. The test load was 125 N, the test frequency was 5 Hz, and the test time was 30 min.

[0060] Table 2 Wear Resistance Test As can be seen from the test results in the above table, the friction coefficient and wear scar diameter of the lubricant gradually decrease with the increase in the content of the fluoroborate wear-resistant pour point depressant. The friction coefficient is minimized to 0.10, and the wear scar diameter is reduced to 1.8 mm, indicating that the prepared lubricant has good anti-friction and anti-wear properties. This is because under friction conditions, the fluoroborate wear-resistant pour point depressant can chemically react with metal elements in mechanical equipment to generate fluorides and boron-containing compounds with high hardness and wear resistance, forming an effective boundary lubricating film, making the metal surface smooth and flat, effectively hindering the catalytic effect of metal on oxidation, reducing the corrosion of corrosive substances on the metal surface, thereby reducing the friction coefficient. At the same time, the quaternary ammonium salt in the fluoroborate wear-resistant pour point depressant can increase the viscosity and film-forming ability of the lubricant, form a stable lubricating film, reduce the friction and wear on the metal surface, effectively prevent the intrusion of external abrasive particles, and reduce wear. Therefore, the lubricant prepared by the present invention has both anti-friction and anti-wear properties. In Comparative Example 1, it does not contain fluoroborate but contains quaternary ammonium salt and has certain wear resistance; Comparative Examples 2 and 3 do not contain fluoroborate and quaternary ammonium salt substances and have poor wear resistance.

[0061] Corrosion resistance test: Referring to the standard SH / T 0331, the surface of a thin copper sheet with dimensions of 50 mm × 50 mm was polished with sandpaper until there were no corrosion spots or stains, completely immersed in the lubricant, placed in an evaporating dish, and baked in an oven at 120 °C for 5 h and then taken out to observe whether there was corrosion on the copper sheet.

[0062] Table 3 Corrosion resistance test As can be seen from the test results in the above table, the copper sheet coated with the lubricant prepared by the present invention shows no change after high-temperature oxidation at 120 °C for 5 h, indicating that the lubricant has excellent anti-corrosion properties. This is because the quaternary ammonium salt cations in the fluoroborate wear-resistant pour point depressant can be adsorbed on the metal surface through electrostatic interaction to form a monomolecular adsorption film. At the same time, structures such as naphthalene rings in the molecule have steric hindrance and hydrophobicity, which can improve the density of the adsorption film and effectively isolate the contact between water or other corrosive substances and the metal, further enhancing the anti-corrosion effect.

[0063] The above detailed description is a specific description of one feasible embodiment of the present invention. This embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification without departing from the present invention shall be included within the scope of the technical solution of the present invention.

Claims

1. A preparation method of a high-performance low-temperature lubricant, characterized in that, The lubricant includes the following components in parts by weight: 75 - 85 parts of base oil, 8 - 12 parts of composite surfactant, 4 - 7 parts of extreme pressure lubricant, 1 - 3 parts of antioxidant, and 0.5 - 2.5 parts of fluoroborate wear-resistant pour point depressant; The preparation method of the high-performance low-temperature lubricant is as follows: Under the condition that the stirring speed is 2500 - 3000 r / min, the base oil, composite surfactant, extreme pressure lubricant, and antioxidant are successively added to a beaker, heated to 80 - 90 °C and mixed evenly, an aqueous sodium chloride solution with a mass fraction of 20 - 30% is added, and stirring continues for 20 - 40 min. Finally, the fluoroborate wear-resistant pour point depressant is added and stirred for 1 - 3 h to obtain the high-performance low-temperature lubricant; The base oil is prepared by blending modified waste cooking oil and white oil in a mass ratio of 2:1; The composite surfactant is prepared by blending OP-10, SP-80, and TW-80 in a mass ratio of 1:1:1; 2. The preparation method of the high-performance low-temperature lubricant according to claim 1, wherein The preparation method of the modified vegetable oil is as follows: Add 10 g of waste cooking oil and 50 mL of isopropanol to a reaction flask. After stirring evenly, add 0.3 - 0.5 g of sodium hydroxide and 4 - 6 g of triethanolamine, and react at 70 - 85 °C for 5 - 8 h. After the reaction ends, cool to room temperature and separate into layers. The upper-layer product is washed with saturated brine, separated by liquid separation, and dried to obtain modified waste cooking oil.

3. The preparation method of the high-performance low-temperature lubricant according to claim 1, wherein The extreme pressure lubricant is prepared by dehydrating pentaerythritol and dodecanedioic acid in a molar ratio of 4:1 at 180 °C; 4. The preparation method of the high-performance low-temperature lubricant according to claim 1, wherein The preparation method of the fluoroborate wear-resistant pour point depressant is as follows: Step (1): Under a nitrogen atmosphere, add 2-(bromomethyl)naphthalene and acetonitrile to a reaction flask. After stirring evenly, add N-methyldiallylamine and stir to react. After the reaction ends, cool to room temperature, precipitate a solid, filter, and dry to obtain an alkenylnaphthalene bromoquaternary ammonium salt intermediate; Step (2): Add the alkenylnaphthalene bromoquaternary ammonium salt intermediate and ethanol to a reaction flask. After stirring evenly, dropwise add tetrafluoroboric acid with a mass fraction of 35 - 45%, and stir to react. After the reaction ends, concentrate, dissolve in ethanol and recrystallize, wash with petroleum ether, and dry to obtain an alkenylnaphthalene tetrafluoroborate quaternary ammonium salt; Step (3): Under a nitrogen atmosphere, add 100 parts of castor oil, 10 - 15 parts of maleic anhydride, and toluene to a reaction flask. After stirring evenly at 45 - 55 °C, add 20 - 30 parts of the alkenylnaphthalene tetrafluoroborate quaternary ammonium salt and 2 - 5 parts of initiator, and react at 85 - 100 °C for 5 - 12 h. After sedimentation, drying, and purification, the fluoroborate wear-resistant pour point depressant is obtained.

5. The preparation method of the high-performance low-temperature lubricant according to claim 4, characterized in that, In the step (1), the mass ratio of 2-(bromomethyl)naphthalene to N-methyldiallylamine is 100:50 - 60; 6. The preparation method of the high-performance low-temperature lubricant according to claim 4, characterized in that, In the step (1), the reaction temperature is 65 - 80 °C, and the reaction time is 12 - 24 h; 7. The preparation method of the high-performance low-temperature lubricant according to claim 4, characterized in that, In the step (2), the ratio of the alkenylnaphthalene bromoquaternary ammonium salt intermediate to tetrafluoroboric acid is 100:65 - 90; 8. The preparation method of the high-performance low-temperature lubricant according to claim 4, characterized in that In the step (2), the reaction temperature is 75 - 90 °C, and the reaction time is 3 - 8 h; 9. The preparation method of the high-performance low-temperature lubricant according to claim 4, characterized in that, In the step (3), the initiator is any one of azobisisobutyronitrile, dimethyl 2,2'-azobis(2-methylpropionate), or benzoyl peroxide.

10. A high-performance low-temperature lubricant, characterized in that, Obtained by the preparation method according to any one of claims 1-9.

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