Preparation method of low-temperature-resistant extreme-pressure wear-resistant bentonite grease

Abstract

The invention relates to the technical field of lubricating grease, in particular to a preparation method of low-temperature-resistant extreme-pressure wear-resistant bentonite lubricating grease, which comprises the following steps: S1, adding part of base oil into a reactor, and heating to 60-90 DEG C; s2, adding the organic modified bentonite into the reactor while stirring, and mixing and stirring; s3, adding a polar dispersing aid, and stirring; s4, slowly adding the residual base oil into the reactor, and stirring; adding an extreme pressure additive, and stirring; and S5, cooling the lubricating grease in the reactor to room temperature, and homogenizing to obtain the bentonite lubricating grease. The bentonite lubricating grease prepared by the invention not only has good low-temperature fluidity at-55 DEG C, but also has good adaptability with an extreme pressure additive, so that the bearing protection capability is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of lubricating grease technology, and specifically to a method for preparing a low-temperature, extreme-pressure, anti-wear bentonite lubricating grease. Background Technology

[0002] In industrial production and daily life, friction and wear are key factors leading to excessive energy consumption and reduced economic lifespan of machinery and equipment. Lubricants, as a core technology for overcoming friction and reducing wear, can be mainly classified into liquid lubricants, semi-solid lubricants, and solid lubricants according to their physical state. Liquid lubricants (such as mineral oil, synthetic oil, and animal and vegetable oils) rely on their fluidity to achieve lubrication, but have limitations in sealing and durability. Solid lubricants (such as layered substances, polymers, and soft metals) perform excellently under special working conditions, but often face challenges such as complex manufacturing processes, high costs, and poor film continuity. In contrast, semi-solid lubricants—namely, greases—often become a better choice for balancing performance and practicality due to their unique system. Greases are colloidal dispersion systems composed of thickeners dispersed in base oils and supplemented with functional additives. They combine the lubricating function of liquids with the sealing and adhesion properties of solids, making them indispensable in fields requiring high reliability and long maintenance cycles, such as mechanical transmission, automotive industry, and aerospace.

[0003] However, when applications extend to extreme low-temperature environments, the performance limits of conventional greases face severe challenges. Conventional low-temperature greases are typically soap-based. On the one hand, the viscosity of the base oil increases dramatically under low-temperature conditions, resulting in significantly reduced fluidity. On the other hand, the interaction of the three-dimensional network structure formed by the thickener intensifies, leading to hardening. During operation, it becomes difficult to release the base oil, resulting in increased starting torque, increased wear area, and seal failure.

[0004] This "low-temperature hardening" effect can directly trigger a series of equipment malfunctions. For example, the starting torque of machinery may increase dramatically, leading not only to a surge in energy consumption but also potentially causing motor overload and burnout. At startup, the friction pairs lack effective oil film lubrication and are in a state of boundary or even dry friction, causing the wear area to expand rapidly and equipment lifespan to decrease drastically. Simultaneously, hardened grease may lose its adhesion to seals, leading to seal failure, leakage, or contaminant intrusion. Therefore, selecting the appropriate grease to meet the requirements of extreme low-temperature operating conditions remains a significant challenge. Bentonite grease is a high-performance grease with high / low temperature performance and antioxidant and shear-resistant properties. Summary of the Invention

[0005] This invention discloses a method for preparing a low-temperature extreme pressure anti-wear bentonite grease. The bentonite grease prepared by this invention not only has good low-temperature fluidity at -55℃, but also has good compatibility with extreme pressure additives, which greatly improves the load-bearing and protective capabilities.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing a low-temperature, extreme-pressure, anti-wear bentonite grease includes the following steps: S1: Add a portion of the base oil to the reactor and heat it to 60~90℃; S2: While stirring, add the organically modified bentonite into the reactor and mix. S3: Add polar dispersant and stir; S4: Slowly add the remaining base oil to the reactor and stir; add the extreme pressure additive and stir. S5: Bentonite grease is prepared by cooling the grease in the reactor to room temperature and homogenizing it.

[0007] Preferably, in step S1, 3 / 5 or 4 / 5 of the total base oil is added to the reactor; in step S2, the mass of the organically modified bentonite accounts for 15% to 20% of the total mass of the grease, and the mixture is stirred for 20 to 40 minutes; in step S3, the mass of the polar dispersant is 20% to 40% of the mass of the bentonite, and the mixture is stirred for 25 to 30 minutes; in step S4, the remaining 2 / 5 or 1 / 5 of the base oil is added slowly to the reactor in batches, with the next batch added only after the previous batch has been completely mixed into the grease; the mixture is stirred for 30 to 40 minutes after each addition; and the extreme pressure additive is added and stirred for 10 minutes.

[0008] Preferably, in step S1, the base oil is selected from synthetic oils, including one or more combinations of polyalphaolefin (PAO), ester oils, perfluoropolyethers, silicone oils, phenyl silicone oils, and methyl silicone oils.

[0009] Preferably, the base oil is one or a combination of PAO4, PAO6, PAO3.5, and diester base oils.

[0010] Preferably, in step S1, the heating temperature is 60~70℃ or 65~70℃.

[0011] Preferably, in step S2, the organically modified bentonite is obtained by modification with a quaternary ammonium salt, wherein the quaternary ammonium salt is one or a combination of several of hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride.

[0012] Preferably, in step S3, the polar dispersant is one or a combination of methanol, ethanol, acetone, and water.

[0013] Preferably, the polar dispersant is a mixture of one of the above-mentioned methanol, ethanol, and acetone with water, in a mass ratio of 80 / 20 to 99 / 1.

[0014] Preferably, in step S4, the extreme pressure additive is one or a combination of several of the following: zinc dialkyl dithiophosphate, molybdenum disulfide, graphene, organic molybdenum, zinc oxide, and ultra-high alkalinity synthetic calcium sulfonate.

[0015] Preferably, in step S5, the material is homogenized by grinding with a three-roll mill, and the grinding is performed 3 to 5 times.

[0016] The method for preparing a low-temperature resistant, extreme-pressure, and anti-wear bentonite grease according to the present invention has the following beneficial effects: 1. The preparation method of the bentonite grease of the present invention is simple, and the thickener is bentonite, which has low cost and is easy to mass-produce.

[0017] 2. The bentonite grease prepared by this invention not only has good low-temperature stability, with a starting torque of 0.09 N·m and a running torque of 0.02 N·m at -55℃, but also has good anti-wear and friction-reducing properties, which can effectively prevent the wear and tear of instruments.

[0018] 3. The bentonite grease of the present invention has broad application prospects in various extremely low temperature operating environments. Attached Figure Description

[0019] Figure 1 The graph shows the change in the coefficient of friction of the bentonite grease prepared in Example 1 over time. Figure 2 The graph shows the change in the coefficient of friction of the bentonite grease prepared in Example 2 over time. Figure 3 The graph shows the coefficient of friction of the bentonite grease prepared in Example 3 as a function of time. Figure 4 The graph shows the change in the coefficient of friction of the bentonite grease prepared in Example 4 over time. Figure 5 The graph shows the change in the coefficient of friction of the bentonite grease prepared in Comparative Example 1 over time. Detailed Implementation

[0020] The following description provides a detailed explanation of the embodiments of the present invention in a step-by-step manner. This description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or a specific orientational structure and operation. Therefore, they should not be construed as limiting this invention.

[0022] Example 1: Weigh 64g of PAO4 base oil and place it in the reactor. Stir magnetically and heat to 65°C.

[0023] Add 20g of organically modified bentonite (modified as hexadecyltrimethylammonium bromide) to the reactor and stir and disperse at 65°C for 30 minutes.

[0024] 6g of polar dispersant (ethanol / water = 95 / 5) was slowly added dropwise into the reactor and stirred at 65°C for 30 minutes.

[0025] Slowly add the remaining 16g of PAO4 base oil to the reactor. After the previous batch has been completely incorporated into the grease, add the next batch of base oil and stir for 30 minutes. Add 3g of ultra-high base number synthetic calcium sulfonate and stir for 10 minutes.

[0026] The grease, cooled to room temperature, was homogenized three times on a three-roll mill to obtain bentonite grease.

[0027] The tribological properties of the prepared bentonite grease were tested using a four-ball testing machine. The test involved three-point sliding contact of steel balls, with the upper ball fixed in a ball container and rotating on three stationary balls below. The bearing steel balls had a diameter of 12.7 mm, the load used in the friction test was 392 N, the temperature was 25 °C, and the test cycle was 60 minutes. After the test, the wear track diameters of the three lower steel balls were measured using an optical microscope. This tribological test under this condition was performed three times to minimize error.

[0028] Example 2: Bentonite grease was prepared using the same method as in Example 1, except that in step S1, 64g of PAO6 base oil was added to the reactor.

[0029] The tribological properties of the prepared bentonite grease were tested using a four-ball testing machine. The test involved three-point sliding contact of steel balls, with the upper ball fixed in a ball container and rotating on three stationary balls below. The bearing steel balls had a diameter of 12.7 mm, the load used in the friction test was 392 N, the temperature was 25 °C, and the test cycle was 60 minutes. After the test, the wear track diameters of the three lower steel balls were measured using an optical microscope. This tribological test under this condition was performed three times to minimize error.

[0030] Example 3: Bentonite grease was prepared using the same method as in Example 1, except that in step S1, 68g of diester base oil was added to the reactor. In step S4, the remaining 17g of diester base oil was added to the reactor.

[0031] The tribological properties of the prepared bentonite grease were tested using a four-ball testing machine. The test involved three-point sliding contact of steel balls, with the upper ball fixed in a ball container and rotating on three stationary balls below. The bearing steel balls had a diameter of 12.7 mm, the load used in the friction test was 392 N, the temperature was 25 °C, and the test cycle was 60 minutes. After the test, the wear track diameters of the three lower steel balls were measured using an optical microscope. This tribological test under this condition was performed three times to minimize error.

[0032] Example 4: Bentonite grease was prepared using the same method as in Example 1, except that: in step S1, 64g of PAO6 base oil was added to the reactor; and in step S2, 20g of organically modified bentonite (modified as octadecyltrimethylammonium bromide) was added to the reactor.

[0033] The tribological properties of the prepared bentonite grease were tested using a four-ball testing machine. The test involved three-point sliding contact of steel balls, with the upper ball fixed in a ball container and rotating on three stationary balls below. The bearing steel balls had a diameter of 12.7 mm, the load used in the friction test was 392 N, the temperature was 25 °C, and the test cycle was 60 minutes. After the test, the wear track diameter of the three lower steel balls was measured using an optical microscope (accuracy 0.01 mm). This tribological test under this condition was performed three times to minimize error.

[0034] Comparative Example 1: Bentonite grease was prepared using the same method as in Example 1, except that no extreme pressure anti-wear agent was added; the grease contained only base oil and thickener, and was designated as Sample 5. The tribological testing conditions were the same as in Example 1, and the measured friction coefficient curve is shown below. Figure 5 As shown.

[0035] Table 1. Physicochemical properties of the bentonite greases prepared in Examples 1-4: Testing items Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Test methods Appearance Light brown uniform ointment Light brown uniform ointment Light brown uniform ointment Light brown uniform ointment Light brown uniform ointment Visual inspection Dropping point / ℃ 289 274 271 265 280 GB / T 3498 Evaporation rate (120℃, 1h) / % (m / m) 1.110 1.075 0.490 0.850 1.083 SH / T 0337 Working cone penetration / 0.1mm 157.4 154.3 163.0 161.0 153.2 GB / T 269 Starting torque / N·m 0.1438 0.1930 0.0991 0.1766 0.1224 SH / T 0338 Operating torque / N·m 0.0164 0.0338 0.0233 0.025 0.0285 SH / T 0338 coefficient of friction 0.0753 0.0730 0.0856 0.0762 0.103 SH / T 0202 Wear scar diameter / mm 0.51 0.50 0.50 0.57 0.82 SH / T 0202

[0036] The experimental data for Examples 1-4 are detailed in Table 1 and... Figure 1-4 Regarding low-temperature performance, all embodiments exhibit excellent low-torque characteristics. In particular, the starting torque of Embodiment 3 is as low as 0.0991 N·m, significantly better than similar products; while the operating torque of Embodiment 1 is only 0.0164 N·m, indicating that its grease is soft and has minimal internal resistance during continuous low-temperature operation, which is beneficial for energy saving, consumption reduction, and long-term stable operation. In terms of the crucial friction-reducing and anti-wear performance, the improvements of this invention are even more significant: compared with the comparative example (friction coefficient 0.103, wear scar diameter 0.82 mm), the friction coefficient of the embodiments can be reduced by up to approximately 30%, and the wear scar diameter can be reduced by up to 39%. The formulation system of this invention can effectively reduce the resistance between friction pairs, successfully overcoming the inherent defect of poor extreme pressure anti-wear properties of traditional bentonite greases, and providing more effective anti-wear protection for equipment.

[0037] In summary, this invention provides a high-performance bentonite grease that can not only start easily and operate smoothly in ultra-low temperature environments of -55℃, but also provide excellent anti-wear protection, significantly expanding the application prospects of bentonite grease under harsh working conditions.

[0038] Example 5: A method for preparing a low-temperature, extreme-pressure, anti-wear bentonite grease includes the following steps: S1: Add a portion of the base oil to the reactor and heat it to 60°C; S2: While stirring, add the organically modified bentonite into the reactor and mix for 20 minutes; S3: Add polar dispersant and stir for 25 minutes; S4: Slowly add the remaining base oil to the reactor and stir for 30 minutes; add the extreme pressure additive and stir for 10 minutes. S5: Bentonite grease is prepared by cooling the grease in the reactor to room temperature and homogenizing it.

[0039] Example 6: A method for preparing a low-temperature, extreme-pressure, anti-wear bentonite grease differs from Example 5 in that: In step S1: heat to 90℃; in step S2: mix and stir for 40 minutes; in step S3: stir for 30 minutes; in step S4: stir for 40 minutes.

[0040] Example 7: Based on embodiments 5 and 6, this embodiment discloses: In step S1, 3 / 5 of the total base oil is added to the reactor; in step S2, the mass of the organically modified bentonite accounts for 15% of the total mass of the grease; in step S3, the mass of the polar dispersant is 20% of the mass of the bentonite; in step S4, the remaining 2 / 5 of the base oil is added slowly into the reactor in batches, with the next batch added only after the previous batch has been completely mixed into the grease.

[0041] Example 8: Based on embodiments 5 and 6, this embodiment discloses: In step S1, 4 / 5 of the total base oil is added to the reactor; in step S2, the mass of the organically modified bentonite accounts for 20% of the total mass of the grease; in step S3, the mass of the polar dispersant is 40% of the mass of the bentonite; in step S4, the remaining 1 / 5 of the base oil is added.

[0042] Example 9: Based on the above embodiments, this embodiment discloses that: in step S1, the implementation method of the base oil is as follows: select synthetic oil, including A1, polyalphaolefin (PAO); A2, ester oil; A3, perfluoropolyether; A4, silicone oil; A5, phenyl silicone oil; A6, methyl silicone oil; wherein, A1-A6 are specific embodiment numbers, the same below; the operator can select one or more of them in combination.

[0043] Example 10: Based on the above embodiments 5-8, this embodiment discloses that: in step S1, the base oil is: B1, PAO4; B2, PAO6; B3, PAO3.5; B4, diester base oil; the operator can select one or more of these combinations.

[0044] Example 11: Based on Example 5, in step S1, the heating temperature is 60~70℃ or 65~70℃.

[0045] Example 12: Based on Example 5: In step S2, the organically modified bentonite is obtained by modification with quaternary ammonium salts, namely: C1, hexadecyltrimethylammonium bromide; C2, octadecyltrimethylammonium bromide; C3, hexadecyltrimethylammonium chloride; C4, octadecyltrimethylammonium chloride; operators may choose one or more of these combinations.

[0046] In step S3, the polar dispersant is: D1, methanol; D2, ethanol; D3, acetone; D4, water; the operator may choose one or a mixture of two of them.

[0047] Example 13: Based on Example 12, the polar dispersant is: E1, a mixture of methanol and water in a mass ratio of 80 / 20 to 99 / 1; E2, or a mixture of ethanol and water in a mass ratio of 80 / 20 to 99 / 1; E3, a mixture of acetone and water in a mass ratio of 80 / 20 to 99 / 1. The operator may choose one of these.

[0048] In step S4, the extreme pressure additives are: F1, zinc dialkyl dithiophosphate; F2, molybdenum disulfide; F3, graphene; F4, organic molybdenum; F5, zinc oxide; F6, ultra-high alkalinity synthetic calcium sulfonate; the operator may select one or more of these additives in combination.

[0049] In step S5, the material is ground and homogenized using a three-roll mill, with the grinding process repeated 3 to 5 times.

[0050] The single thickener bentonite used in this invention is made from natural bentonite, which causes less environmental pollution and is safer for users. The preparation method is simple, the cost is low, and it is easy to mass-produce. More importantly, the prepared bentonite grease not only has good low-temperature stability but also excellent friction-reducing and anti-wear properties, providing long-lasting lubrication at ultra-low temperatures and effectively preventing wear on mechanical equipment.

Claims

1. A method for preparing a low-temperature, extreme-pressure, anti-wear bentonite grease, characterized in that, Includes the following steps: S1: Add a portion of the base oil to the reactor and heat it to 60~90℃; S2: While stirring, add the organically modified bentonite into the reactor and mix. S3: Add polar dispersant and stir; S4: Slowly add the remaining base oil to the reactor and stir; add the extreme pressure additive and stir. S5: Bentonite grease is prepared by cooling the grease in the reactor to room temperature and homogenizing it.

2. The preparation method of the low-temperature extreme pressure anti-wear bentonite grease as described in claim 1, characterized in that, In step S1, 3 / 5 or 4 / 5 of the total base oil is added to the reactor; in step S2, the mass of the organically modified bentonite accounts for 15% to 20% of the total mass of the grease, and the mixture is stirred for 20 to 40 minutes; in step S3, the mass of the polar dispersant is 20% to 40% of the mass of the bentonite, and the mixture is stirred for 25 to 30 minutes; in step S4, the remaining 2 / 5 or 1 / 5 of the base oil is added slowly to the reactor in batches, with the next batch added only after the previous batch has been completely mixed into the grease; the mixture is stirred for 30 to 40 minutes after each addition; and the extreme pressure additive is added and stirred for 10 minutes.

3. The preparation method of the low-temperature extreme pressure anti-wear bentonite grease as described in claim 1, characterized in that, In step S1, the base oil is selected from synthetic oils, including one or more combinations of polyalphaolefin (PAO), ester oils, perfluoropolyethers, silicone oils, phenyl silicone oils, and methyl silicone oils.

4. The method for preparing a low-temperature resistant, extreme-pressure, anti-wear bentonite grease as described in claim 1, characterized in that, The base oil is one or a combination of PAO4, PAO6, PAO3.5, and diester base oils.

5. The preparation method of the low-temperature extreme pressure anti-wear bentonite grease as described in claim 1, characterized in that, In step S1, the heating temperature is 60~70℃ or 65~70℃.

6. The method for preparing a low-temperature resistant, extreme-pressure, anti-wear bentonite grease as described in claim 1, characterized in that, In step S2, the organically modified bentonite is obtained by modification with a quaternary ammonium salt, wherein the quaternary ammonium salt is one or a combination of several of hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride.

7. The preparation method of the low-temperature extreme pressure anti-wear bentonite grease as described in claim 1, characterized in that, In step S3, the polar dispersant is one or a combination of methanol, ethanol, acetone, and water.

8. The method for preparing a low-temperature resistant, extreme-pressure, anti-wear bentonite grease as described in claim 1, characterized in that, The polar dispersant is a mixture of one of the above-mentioned methanol, ethanol, and acetone with water, in a mass ratio of 80 / 20 to 99 / 1.

9. The method for preparing a low-temperature resistant, extreme-pressure, anti-wear bentonite grease as described in claim 1, characterized in that, In step S4, the extreme pressure additive is one or a combination of several of the following: zinc dialkyl dithiophosphate, molybdenum disulfide, graphene, organic molybdenum, zinc oxide, and ultra-high alkalinity synthetic calcium sulfonate.

10. The method for preparing a low-temperature resistant, extreme-pressure, anti-wear bentonite grease as described in claim 1, characterized in that, In step S5, the material is ground and homogenized using a three-roll mill, with the grinding process repeated 3 to 5 times.

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