Preparation process of lubricating grease containing carbon nanotubes

Abstract

The invention relates to the technical field of lubricating grease, and discloses a preparation process of lubricating grease containing carbon nanotubes, which comprises the following steps: adding 70-80 parts by weight of fluorosilicone oil, 20-30 parts by weight of polytetrafluoroethylene and 0.02-0.4 part by weight of fluorosilicone modified carbon nanotubes into a grease preparation kettle, stirring and blending, cooling and grinding to obtain the lubricating grease containing the carbon nanotubes. Polymer molecular chains containing trifluoromethyl and siloxane structures are grafted on the surfaces of the carbon nanotubes, so that the compatibility between the carbon nanotubes and fluorosilicone oil is better, the carbon nanotubes are uniformly dispersed in a fluorosilicone oil lubricating grease matrix, and as an anti-wear additive, the carbon nanotubes can better play a self-lubricating role and play a nano-scale tiny bearing role in the lubricating process, so that the wear resistance of the carbon nanotubes is improved. The grinding crack diameter and the friction coefficient of the lubricating grease are reduced, and the wear resistance of the lubricating grease is improved.

Description

Technical Field

[0001] The invention relates to the technical field of lubricating grease, in particular to a preparation process of lubricating grease containing carbon nanotubes. Background Art

[0002] Silicone oil-based grease has excellent low-temperature fluidity, thermal stability and other properties, and is widely used in aerospace, electronics, automotive machinery and other fields. Fluorine is introduced into the side chain of silicone oil, and the obtained fluorosilicone oil has better lubricity, anti-oxidation and other properties. In order to further improve the anti-wear performance of fluorosilicone oil grease, it is necessary to add anti-wear additives, such as inorganic fillers such as bentonite and molybdenum disulfide. The invention patent with the existing announcement number CN105733754B discloses an insulating grease containing fluorine silicone oil and a preparation method thereof. It uses fluorosilicone oil, polytetrafluoroethylene, coupling agent, fumed silica, molybdenum disulfide, powder surface treatment agent, mildew inhibitor and the like as raw materials, and the prepared insulating grease has good oil resistance, solvent resistance, heat resistance and other properties, but the insulating grease has a complex composition, which is not conducive to actual industrial production.

[0003] Carbon nanotubes have a unique two-dimensional tubular nanostructure and excellent self-lubricating properties, and are widely used in greases. Surface modification of carbon nanotubes can improve their dispersibility in greases. The document "Preparation and Tribological Properties of Carbon Nanotube-Based Bentonite Grease" describes the use of oleic acid to modify multi-walled carbon nanotubes, which can be evenly and stably dispersed in PAO6 base oil. The resulting grease has good tribological properties, but the oleic acid-modified multi-walled carbon nanotubes do not show good dispersibility in fluorosilicone oil grease. Summary of the invention

[0004] The invention solves the problem that the existing fluorosilicone oil grease has complex raw materials and poor anti-wear performance.

[0005] The technical solution of the present invention is as follows: A preparation process of grease containing carbon nanotubes: (1) Add triethylamine, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane (CAS No. 18001-97-3), and 2,2-bis(4-acylchloridophenyl)hexafluoropropane to N,N-dimethylformamide, and perform polymerization reaction in a nitrogen atmosphere to generate a hydroxy-terminated fluorosilicon polymer; then add acyl chloride carbon nanotubes to perform grafting reaction, filter, wash with water, N,N-dimethylformamide, and dichloromethane in turn, and dry to obtain fluorosilicon-modified carbon nanotubes. The preparation reaction route is: .

[0006] (2) Add 70-80 parts by weight of fluorosilicone oil to a grease-making kettle, heat to the blending temperature, evacuate, add 20-30 parts by weight of polytetrafluoroethylene and 0.02-0.4 parts by weight of fluorosilicone-modified carbon nanotubes, stir and blend, cool after discharging, and grind three times in a three-roll mill to obtain a grease containing carbon nanotubes.

[0007] Furthermore, the ratio of triethylamine, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, 2,2-bis(4-acylchlorophenyl)hexafluoropropane, and acyl chloride carbon nanotubes in (1) is (100-240 mmol): (55-132 mmol): (50-120 mmol): 100 g.

[0008] Furthermore, the polymerization reaction in (1) is stirred at 20-35° C. for 8-12 hours.

[0009] Furthermore, the grafting reaction in (1) is stirred at 70-100° C. for 36-48 hours.

[0010] Furthermore, in said (2), the blending temperature is 160-180° C., and the blending time is 3-6 hours.

[0011] Furthermore, the preparation process of 2,2-bis(4-chlorophenyl)hexafluoropropane is as follows: add 2,2-bis(4-carboxyphenyl)hexafluoropropane (CAS No. 1171-47-7) and catalyst N,N-dimethylformamide to thionyl chloride in a ratio of (16-20mL): 1g: (6-8μL); heat to 70-75°C, stir and reflux for acyl chlorination reaction for 3-5h, distill under reduced pressure, and recrystallize the product in dichloromethane to obtain 2,2-bis(4-chlorophenyl)hexafluoropropane. The preparation reaction formula is: .

[0012] Furthermore, the preparation process of the chlorinated carbon nanotubes is as follows: adding carbon nanotubes to concentrated nitric acid, ultrasonically dispersing, heating to 80-90°C, condensing and refluxing for 8-12h, filtering, washing with water, drying, obtaining carboxylated carbon nanotubes and adding them to thionyl chloride, adding N,N-dimethylformamide, heating to 70-75°C, condensing and refluxing for 24-36h, filtering, washing with dichloromethane, drying, obtaining chlorinated carbon nanotubes. The preparation reaction route is: .

[0013] The beneficial effects of the present invention are as follows: 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane and 2,2-bis(4-acyl chloride phenyl)hexafluoropropane are used for polymerization reaction to obtain a fluorosilicone copolymer with terminal hydroxyl groups, and then the terminal hydroxyl groups react with the acyl chloride groups on the surface of carbon nanotubes to obtain fluorosilicone-modified carbon nanotubes. The present invention uses fluorosilicone-modified carbon nanotubes as anti-wear additives, fluorosilicone oil as base oil, and polytetrafluoroethylene as thickener to blend and obtain fluorosilicone oil grease. The fluorosilicone oil grease of the present invention has simple ingredients and is convenient for industrial production. At the same time, polymer molecular chains containing trifluoromethyl and siloxane structures are grafted on the surface of carbon nanotubes, so that the compatibility between carbon nanotubes and fluorosilicone oil is better and they are evenly dispersed in the fluorosilicone oil grease matrix, which can better play a self-lubricating role and play a nano-scale micro-bearing role in the lubrication process, thereby reducing the wear scar diameter and friction coefficient of the grease and improving the anti-wear performance of the grease. DETAILED DESCRIPTION

[0014] The technical solution of the present invention will be clearly and completely described below through the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0015] The following fluorosilicone oil, model HOTOLUBE fluorosilicone grease, was purchased from Shanghai Hutou Chemical Co., Ltd. Polytetrafluoroethylene, model nano-grade J24, was purchased from Shanghai Hongshunjiang New Materials Co., Ltd. The diameter of carbon nanotubes was between 8-15nm and the length was 0.5-2μm, purchased from Beijing Dekedaojin Technology Co., Ltd.

[0016] Example 1 (1) Add 0.5 g of 2,2-bis(4-carboxyphenyl)hexafluoropropane and 4 μL of N,N-dimethylformamide to 8 mL of thionyl chloride, heat to 75 °C, stir and reflux for 3 h, distill under reduced pressure, and recrystallize the product from dichloromethane to obtain 2,2-bis(4-acylchloridophenyl)hexafluoropropane.

[0017] (2) Add 0.2 g of carbon nanotubes to 100 mL of 70% by mass nitric acid, disperse by ultrasonication, heat to 80 °C, stir and condense under reflux for 8 h, filter, wash with water, and dry. Then add the carbon nanotubes to 50 mL of thionyl chloride, add 2.5 mL of N,N-dimethylformamide, heat to 70 °C, stir and condense under reflux for 36 h, filter, wash with dichloromethane, and dry to obtain acyl chloride carbon nanotubes.

[0018] (3) To 60 mL of N,N-dimethylformamide, 0.18 mmol of triethylamine, 0.1 mmol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane and 0.09 mmol of 2,2-bis(4-chlorophenyl)hexafluoropropane were added, and the mixture was stirred at 20°C for 12 h in a nitrogen atmosphere. Then, 0.1 g of acyl chloride carbon nanotubes was added, and the mixture was stirred at 80°C for 48 h. After filtering, the mixture was washed with water, N,N-dimethylformamide and dichloromethane in sequence, and dried to obtain fluorine-silicon modified carbon nanotubes.

[0019] (4) Add 75 g of fluorosilicone oil to a grease-making kettle, heat to the blending temperature, evacuate, add 25 g of polytetrafluoroethylene and 0.02 g of fluorosilicone-modified carbon nanotubes, stir and blend, cool after discharging, and grind three times in a three-roll mill to obtain a grease containing carbon nanotubes.

[0020] Example 2 (1) Add 0.5 g of 2,2-bis(4-carboxyphenyl)hexafluoropropane and 3 μL of N,N-dimethylformamide to 10 mL of thionyl chloride, heat to 70°C, stir and reflux for 5 h, distill under reduced pressure, and recrystallize the product from dichloromethane to obtain 2,2-bis(4-chlorophenyl)hexafluoropropane.

[0021] (2) Add 0.2 g of carbon nanotubes to 70 mL of 70% by mass concentrated nitric acid, disperse by ultrasonication, heat to 90 °C, stir and condense under reflux for 12 h, filter, wash with water, and dry. Then add the carbon nanotubes to 40 mL of thionyl chloride, add 2 mL of N,N-dimethylformamide, heat to 75 °C, stir and condense under reflux for 24 h, filter, wash with dichloromethane, and dry to obtain acyl chloride carbon nanotubes.

[0022] (3) To 80 mL of N,N-dimethylformamide, 0.24 mmol of triethylamine, 0.132 mmol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane and 0.12 mmol of 2,2-bis(4-chlorophenyl)hexafluoropropane were added, and the mixture was stirred at 35°C for 8 h in a nitrogen atmosphere. Then, 0.1 g of acyl chloride carbon nanotubes was added, and the mixture was stirred at 70°C for 48 h. After filtering, the mixture was washed with water, N,N-dimethylformamide and dichloromethane in sequence, and dried to obtain fluorine-silicon modified carbon nanotubes.

[0023] (4) Add 70 g of fluorosilicone oil to a grease-making kettle, heat to the blending temperature, evacuate, add 30 g of polytetrafluoroethylene and 0.1 g of fluorosilicone-modified carbon nanotubes, stir and blend, cool after discharging, and grind three times in a three-roll mill to obtain a grease containing carbon nanotubes.

[0024] Example 3 (1) To 50 mL of N,N-dimethylformamide, 0.1 mmol of triethylamine, 0.055 mmol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, and 0.05 mmol of 2,2-bis(4-chlorophenyl)hexafluoropropane (prepared according to the method of Example 1) were added, and the mixture was stirred at 25° C. for 12 h in a nitrogen atmosphere. Then, 0.1 g of chlorinated carbon nanotubes (prepared according to the method of Example 1) was added, and the mixture was stirred at 100° C. for 36 h. After filtering, the mixture was washed with water, N,N-dimethylformamide, and dichloromethane in sequence, and dried to obtain fluorine-silicon-modified carbon nanotubes.

[0025] (2) Add 80 g of fluorosilicone oil to a grease-making kettle, heat to the blending temperature, evacuate, add 20 g of polytetrafluoroethylene and 0.2 g of fluorosilicone-modified carbon nanotubes, stir and blend, cool after discharging, and grind three times in a three-roll mill to obtain a grease containing carbon nanotubes.

[0026] Example 4 (1) Add 75 g of fluorosilicone oil to a grease-making kettle, heat to the blending temperature, evacuate, add 25 g of polytetrafluoroethylene and 0.3 g of fluorosilicone-modified carbon nanotubes (prepared according to the method of Example 1), stir and blend, cool after discharging, and grind three times in a three-roll grinder to obtain a grease containing carbon nanotubes.

[0027] Example 5 (1) Add 75 g of fluorosilicone oil to a grease-making kettle, heat to the blending temperature, evacuate, add 25 g of polytetrafluoroethylene and 0.4 g of fluorosilicone-modified carbon nanotubes (prepared according to the method of Example 1), stir and blend, cool after discharging, and grind three times in a three-roll mill to obtain grease.

[0028] Comparative Example 1 (1) Add 75 g of fluorosilicone oil to a grease-making kettle, heat to the blending temperature, evacuate, add 25 g of polytetrafluoroethylene, stir and blend, cool after discharge, and grind three times in a three-roll mill to obtain grease.

[0029] Comparative Example 2 (1) Add 75 g of fluorosilicone oil to a grease-making kettle, heat to the blending temperature, evacuate, add 25 g of polytetrafluoroethylene and 0.02 g of carbon nanotubes, stir and blend, cool after discharging, and grind three times in a three-roll mill to obtain a grease containing carbon nanotubes.

[0030] Comparative Example 3 (1) To 60 mL of N,N-dimethylformamide, 0.18 mmol of triethylamine, 0.1 mmol of 1,6-hexanediamine, and 0.09 mmol of 2,2-bis(4-chlorophenyl)hexafluoropropane were added, and the mixture was stirred at 20°C for 12 h in a nitrogen atmosphere. Then, 0.1 g of acyl chloride carbon nanotubes was added, and the mixture was stirred at 80°C for 48 h. After filtering, the mixture was washed with water, N,N-dimethylformamide, and dichloromethane in sequence, and dried to obtain fluorine-modified carbon nanotubes.

[0031] (2) Add 75 g of fluorosilicone oil to a grease-making kettle, heat to the blending temperature, evacuate, add 25 g of polytetrafluoroethylene and 0.02 g of fluorine-modified carbon nanotubes, stir and blend, cool after discharging, and grind three times in a three-roll mill to obtain a grease containing carbon nanotubes.

[0032] Comparative Example 4 (1) To 60 mL of N,N-dimethylformamide, 0.18 mmol of triethylamine, 0.1 mmol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane and 0.09 mmol of terephthaloyl chloride were added, and the mixture was stirred at 20°C for 12 h in a nitrogen atmosphere. Then, 0.1 g of acyl chloride carbon nanotubes was added, and the mixture was stirred at 80°C for 48 h. After filtering, the mixture was washed with water, N,N-dimethylformamide and dichloromethane in sequence, and dried to obtain silicon-modified carbon nanotubes.

[0033] (2) Add 75 g of fluorosilicone oil to a grease-making kettle, heat to the blending temperature, evacuate, add 25 g of polytetrafluoroethylene and 0.02 g of silicon-modified carbon nanotubes, stir and blend, cool after discharging, and grind three times in a three-roll mill to obtain a grease containing carbon nanotubes.

[0034] The wear scar diameter and anti-wear performance of the grease were tested using a four-ball testing machine according to the SH / T 0204-1992 method. During the test, the four-ball testing machine recorded the corresponding friction coefficient, as shown in Table 1.

[0035] Table 1 Grease anti-wear performance test

[0036] As can be seen from Table 1, the wear scar diameter and friction coefficient of the fluorosilicone oil grease in Comparative Example 1 are large, and the anti-wear performance is poor. Fluorosilicone oil greases in Examples 1 to 5 are added with fluorosilicone modified carbon nanotubes, and polymer molecular chains containing trifluoromethyl and siloxane structures are grafted on the surface of the carbon nanotubes, so that the compatibility between the fluorosilicone modified carbon nanotubes and the fluorosilicone oil is better and evenly dispersed in the fluorosilicone oil grease matrix, which can better play a self-lubricating role. Fluorosilicone modified carbon nanotubes, as anti-wear additives, play the role of nano-scale micro bearings in the lubrication process, reduce the wear scar diameter and friction coefficient of the grease, and improve the anti-wear performance of the grease.

[0037] Compared with Example 1, the carbon nanotubes added in Comparative Example 2 have poor compatibility with fluorosilicone oil, poor dispersibility in the grease, and fail to exert a good self-lubricating effect, resulting in the wear scar diameter and friction coefficient of the grease being greater than those in Example 1, and the anti-wear performance of the grease being poor.

[0038] Compared with Example 1, Comparative Example 3 uses 1,6-hexanediamine as a raw material, and the prepared fluorine-modified carbon nanotubes do not contain a siloxane structure, and the compatibility and dispersibility with fluorosilicone oil grease are lower than those in Example 1; Comparative Example 4 uses terephthaloyl chloride as a raw material, and the prepared silicon-modified carbon nanotubes do not contain fluorine element, and the compatibility and dispersibility with fluorosilicone oil grease are lower than those in Example 1. The wear scar diameter and friction coefficient of the grease in Comparative Examples 3 and 4 are both greater than those in Example 1, and the anti-wear performance of the grease is poor.

[0039] The above-described embodiments provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected.

Claims

1. A process for preparing a grease containing carbon nanotubes, characterized in that: The preparation process comprises: (1) adding triethylamine, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane and 2,2-bis(4-acylchlorophenyl)hexafluoropropane to N,N-dimethylformamide, and performing polymerization reaction in a nitrogen atmosphere, and then adding acyl chloride carbon nanotubes to perform grafting reaction, filtering, washing with water, N,N-dimethylformamide and dichloromethane in turn, and drying to obtain fluorine-silicon modified carbon nanotubes; (2) Add 70-80 parts by weight of fluorosilicone oil to a grease-making kettle, heat to the blending temperature, evacuate, add 20-30 parts by weight of polytetrafluoroethylene and 0.02-0.4 parts by weight of fluorosilicone-modified carbon nanotubes, stir and blend, cool and grind to obtain a grease containing carbon nanotubes.

2. The process for preparing a grease containing carbon nanotubes according to claim 1, characterized in that: The ratio of triethylamine, 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, 2,2-bis(4-chlorophenyl)hexafluoropropane and chlorinated carbon nanotubes in (1) is (100-240 mmol): (55-132 mmol): (50-120 mmol): 100 g.

3. The process for preparing a grease containing carbon nanotubes according to claim 1, characterized in that: The polymerization reaction in (1) is stirred at 20-35°C for 8-12 hours.

4. The process for preparing a grease containing carbon nanotubes according to claim 1, characterized in that: The grafting reaction in (1) is stirred at 70-100° C. for 36-48 hours.

5. The process for preparing a grease containing carbon nanotubes according to claim 1, characterized in that: In the step (2), the blending temperature is 160-180° C. and the blending time is 3-6 h.

6. The process for preparing a grease containing carbon nanotubes according to claim 2, characterized in that: The preparation process of 2,2-bis(4-chlorophenyl)hexafluoropropane is as follows: 2,2-bis(4-carboxyphenyl)hexafluoropropane and N,N-dimethylformamide are added to thionyl chloride to carry out chlorination reaction, and the product is distilled under reduced pressure and recrystallized in dichloromethane to obtain 2,2-bis(4-chlorophenyl)hexafluoropropane.

7. The process for preparing a grease containing carbon nanotubes according to claim 6, characterized in that: The ratio of thionyl chloride, 2,2-bis(4-carboxyphenyl)hexafluoropropane and N,N-dimethylformamide is (16-20 mL): 1 g: (6-8 μL).

8. The process for preparing a grease containing carbon nanotubes according to claim 6, characterized in that: The acyl chloride reaction was stirred at 70-75°C and refluxed under condensation for 3-5h.

9. The process for preparing a grease containing carbon nanotubes according to claim 2, characterized in that: The preparation process of the acyl chloride carbon nanotubes is as follows: adding the carbon nanotubes to concentrated nitric acid, ultrasonically dispersing, heating to 80-90° C., condensing and refluxing for 8-12 hours, filtering, washing with water, and drying, then adding the carbon nanotubes to thionyl chloride, adding N,N-dimethylformamide, heating to 70-75° C., condensing and refluxing for 24-36 hours, filtering, washing with dichloromethane, and drying to obtain the acyl chloride carbon nanotubes.

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