A lubricating grease, its preparation method and application

Abstract

This invention discloses a lubricating grease, its preparation method, and its application. The preparation method of the lubricating grease includes the following steps: S1, sequentially subjecting waste gear oil to sedimentation, coarse filtration, centrifugation, distillation, and fine filtration; S2, mixing the finely filtered waste gear oil with base oil and additives, and then adding a thickener for thickening treatment to obtain the lubricating grease. This invention utilizes waste gear oil to prepare lubricating grease products, which not only reduces the environmental harm caused by waste gear oil but also enables the recycling and reuse of waste gear oil, reducing the production cost of lubricating grease. It has high environmental value and economic benefits. Furthermore, the method is simple, easy to operate, and readily applicable to large-scale production; and the resulting lubricating grease exhibits good overall performance.

Description

Technical Field

[0001] This invention belongs to the field of lubricating grease preparation technology. Specifically, this invention relates to a lubricating grease, its preparation method, and its application. Background Technology

[0002] In wind turbines, the gearbox is a crucial mechanical component, operating under harsh conditions for extended periods, thus requiring high-quality gear oil for lubrication. However, during use, gear oil undergoes physical and chemical reactions that lead to aging, or it becomes contaminated with substances such as moisture, dust, metal shavings from mechanical wear, and oxidation-induced compounds like carboxylic acids, organic acid salts, asphaltenes, carbon deposits, and sludge. This renders its lubricating performance substandard, turning it into waste gear oil. With the increasing demand for gear oil, the amount of waste gear oil generated is also increasing, placing greater pressure on the environment. Therefore, the recycling and reuse of waste gear oil is of great significance. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a method for preparing lubricating grease using waste gear oil, so as to realize the recycling and reuse of waste gear oil.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, embodiments of the present invention provide a method for preparing a lubricating grease, comprising the following steps:

[0006] S1, the waste gear oil is sequentially subjected to sedimentation, coarse filtration, centrifugation, distillation and fine filtration;

[0007] S2, after finely filtering the waste gear oil, mix it with base oil and additives, add a thickener and thicken it to obtain the grease.

[0008] The embodiments of the present invention, by sequentially employing sedimentation, coarse filtration, centrifugation, distillation, and fine filtration, can effectively remove impurities from waste gear oil, and further compound base oil, additives, and thickeners to produce new lubricating grease. This not only reduces the environmental harm of waste gear oil, but also achieves resource regeneration and improves resource reuse rate; moreover, the method is simple to operate, has a simple process, and is easy to implement.

[0009] In some embodiments, during the settling process, the temperature of the waste gear oil is 60–100°C, and the settling time is 120–180 min.

[0010] And / or, the coarse filtration is performed by plate and frame filtration, and the pore size of the filter element used in the coarse filtration is 5 to 10 μm;

[0011] And / or, during centrifugation, the temperature of the waste gear oil is 60–100°C;

[0012] And / or, the distillation method includes at least one of vacuum distillation or molecular distillation; the distillation temperature is 160–200°C, the vacuum degree is <0.09 mPa, and the distillation time is 2–4 h;

[0013] And / or, the instrument used in the fine filtration is a bag filter; the pore size of the filter membrane of the bag filter is 1-5 μm, and the circulation filtration time is 2-4 h.

[0014] In some embodiments, the waste gear oil after fine filtration is 70-95 parts by weight, the base oil is 1-20 parts by weight, the additive is 0.5-4 parts by weight, and the thickener is 8-15 parts by weight.

[0015] In some embodiments, the base oil is a PAO-type base oil.

[0016] In some embodiments, the additive comprises a mixture of extreme pressure anti-wear agent, anti-foaming agent and demulsifier; the extreme pressure anti-wear agent is present in a weight ratio of 0.01 to 3 parts, the anti-foaming agent in a weight ratio of 0.001 to 0.1 parts, and the demulsifier in a weight ratio of 0.001 to 0.1 parts.

[0017] In some embodiments, the extreme pressure anti-wear agent includes at least one of sulfurized isobutylene or sulfurized lard;

[0018] And / or, the antifoaming agent includes at least one of dimethyl silicone oil, amino silicone oil, or methacrylic acid;

[0019] And / or, the demulsifier includes at least one of hexanediol ester, propylene oxide / ethylene oxide copolymer, or polyether polymer.

[0020] In some embodiments, the thickener includes at least one of lithium stearate or 12-hydroxystearic acid;

[0021] And / or, the thickening treatment temperature is 180–210°C, and the thickening treatment time is 1–3 hours.

[0022] In some embodiments, the kinematic viscosity of the waste gear oil at 40°C is 256–384 mm. 2 / s, cleanliness > 10 grade, anti-foaming performance > 300 / 0, moisture content > 500ppm, deemulsification performance > 60min;

[0023] And / or, the kinematic viscosity of the finely filtered waste gear oil at 40°C is 288–352 mmHg. 2 / s, cleanliness ≤ 8, anti-foaming performance < 100 / 0, moisture content < 300 ppm, deemulsification performance < 30 min.

[0024] Secondly, embodiments of the present invention also provide a lubricating grease, which is prepared by the preparation method described in the first aspect.

[0025] Thirdly, embodiments of the present invention also propose the application of the lubricating grease as described in the second aspect in a wind turbine generator.

[0026] The advantages and beneficial effects of this invention are as follows:

[0027] This invention utilizes waste gear oil to prepare lubricating grease products, which not only reduces the environmental harm caused by waste gear oil but also enables the recycling and reuse of waste gear oil, reducing the production cost of lubricating grease and achieving a win-win situation for both environmental and economic benefits. Furthermore, the method is simple, easy to operate, and readily applicable to large-scale production; and the resulting lubricating grease exhibits good overall performance. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of the lubricating grease preparation method according to an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0030] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0031] In this document, when values ​​are described as ranges, it should be understood that such disclosure includes disclosure of all possible subranges within that range, as well as the specific numerical values ​​falling within that range, regardless of whether the specific numerical value or specific subrange is explicitly specified.

[0032] In this article, the words “contain” and “include” and their various variations mean that other elements or wholes may be included but not specifically described.

[0033] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three kinds of relationships. For example, A and / or B can represent three cases: A exists alone, A and B exist simultaneously, and B exists alone.

[0034] Firstly, such as Figure 1 As shown in the figure, an embodiment of the present invention proposes a method for preparing a lubricating grease, comprising the following steps:

[0035] S1, the waste gear oil is sequentially subjected to sedimentation, coarse filtration, centrifugation, distillation and fine filtration;

[0036] S2, after finely filtering the waste gear oil, mix it with base oil and additives, and then add a thickener to thicken it to obtain lubricating grease.

[0037] The grease preparation method in this embodiment of the invention can effectively recycle and reuse waste gear oil, reducing resource waste. Through steps such as sedimentation, coarse filtration, centrifugation, distillation and fine filtration, the cleanliness and moisture content of the oil can be improved. By adding additives, the extreme pressure anti-wear performance, anti-foaming performance and anti-emulsification performance of the grease can be improved. Finally, the thickening process produces a grease product with higher added value, realizing the recycling of lubricating oil products.

[0038] In some specific embodiments, during sedimentation, the temperature of the waste gear oil is 60–100°C (non-limiting examples include 60°C, 75°C, 80°C, 90°C, or 100°C, etc.), the sedimentation time is 120–180 min (non-limiting examples include 120 min, 135 min, 150 min, 160 min, or 180 min, etc.), and the device used in the sedimentation process is a sedimentation separator. Since the higher the viscosity of the oil, the more difficult the sedimentation, for wind power gear oil with high viscosity, it is necessary to reduce its viscosity by heating, thereby accelerating the sedimentation rate.

[0039] And / or, the coarse filtration method is plate and frame filtration, the instrument used is a plate and frame filter press, and the pore size of the filter element used in coarse filtration is 5-10μm (non-limiting examples, such as 5μm, 6.5μm, 7μm, 8μm, 10μm, etc.); by using sedimentation and coarse filtration, large particles, large water droplets or dust in waste gear oil can be removed first;

[0040] And / or, during centrifugation, the temperature of the waste gear oil is 60-100°C (non-limiting examples such as 60°C, 75°C, 80°C, 90°C, or 100°C, etc.). Heating reduces the viscosity of the waste gear oil, thereby improving centrifugal filtration efficiency. Centrifugation removes small suspended particles and water droplets from the waste gear oil.

[0041] And / or, the distillation method includes at least one of vacuum distillation or molecular distillation; the distillation temperature is 160–200°C (non-limiting examples: 160°C, 180°C, 185°C, or 200°C, etc.), the vacuum degree is <0.09 mPa (non-limiting examples: 0.08 mPa, 0.06 mPa, 0.05 mPa, or 0.02 mPa, etc.), and the distillation time is 2–4 h (non-limiting examples: 2 h, 2.5 h, 3 h, or 4 h, etc.); by distilling waste gear oil, residual water in the waste gear oil can be removed; and it should be noted that during the distillation process, adsorption can also be achieved by adding bleaching clay or activated carbon to achieve better distillation results;

[0042] And / or, the instrument used in fine filtration is a bag filter; the pore size of the filter membrane of the bag filter is 1 to 5 μm (non-limiting examples, such as 1 μm, 2 μm, 3.5 μm, 4 μm, 5 μm, etc.), and the circulation filtration time is 2 to 4 h (non-limiting examples, such as 2 h, 2.5 h, 3 h, or 4 h, etc.); by further fine filtration of waste gear oil, residual impurities in waste gear oil can be removed.

[0043] Specifically, before impurity removal treatment, the kinematic viscosity of the waste gear oil at 40°C is 256–384 mm. 2 / s, cleanliness >10 grade, anti-foaming performance >300 / 0, water content >500ppm, deemulsification performance >60min; and after a series of impurity removal treatments, the kinematic viscosity of the finely filtered waste gear oil at 40℃ is 288~352mm. 2 / s, cleanliness ≤ 8 grade, anti-foaming performance < 100 / 0, moisture content < 300 ppm, deemulsification performance < 30 min (wherein, the determination of kinematic viscosity refers to GB / T 265, the determination of cleanliness refers to DL / T, the determination of anti-foaming performance refers to GB / T12579, the determination of moisture content refers to GB / T 260, and the determination of deemulsification performance refers to GB / T 7305).

[0044] In some specific embodiments, the waste gear oil after fine filtration is 70 to 95 parts by weight (non-limiting examples: 70 parts, 75 parts, 80 parts, 90 parts or 95 parts, etc.), the base oil is 1 to 20 parts by weight (non-limiting examples: 1 part, 5 parts, 10 parts, 15 parts or 20 parts, etc.), the additive is 0.5 to 4 parts by weight (non-limiting examples: 0.5 parts, 1 part, 2.5 parts, 3 parts or 4 parts, etc.), and the thickener is 8 to 15 parts by weight (non-limiting examples: 8 parts, 10 parts, 12 parts or 15 parts, etc.).

[0045] In some specific embodiments, the base oil is a PAO-type base oil.

[0046] In some specific embodiments, the additives include a mixture of extreme pressure anti-wear agent, antifoaming agent, and demulsifier; and the extreme pressure anti-wear agent is present in a weight ratio of 0.01 to 3 parts (non-limiting examples include: 0.01 parts, 0.5 parts, 0.9 parts, 1 part, 2.5 parts, or 3 parts, etc.), the antifoaming agent is present in a weight ratio of 0.001 to 0.1 parts (non-limiting examples include: 0.001 parts, 0.01 parts, 0.05 parts, or 0.1 parts, etc.), and the demulsifier is present in a weight ratio of 0.001 to 0.1 parts (non-limiting examples include: 0.001 parts, 0.008 parts, 0.01 parts, 0.05 parts, or 0.1 parts, etc.);

[0047] Furthermore, the extreme pressure anti-wear agent includes at least one of sulfurized isobutylene or sulfurized lard;

[0048] And / or, the antifoaming agent includes at least one of dimethyl silicone oil, amino silicone oil, or methacrylic acid;

[0049] And / or, the demulsifier includes at least one of hexanediol ester, propylene oxide / ethylene oxide copolymer, or polyether polymer (e.g., glycerol polyether, polyoxyethylene (polyoxypropylene) ether, polypropylene glycol, etc.).

[0050] Adding extreme pressure anti-wear agents ensures that the oil has sufficient extreme pressure anti-wear performance and can withstand impact loads. If the amount added is too low, the performance requirements will not be met, and if the amount added is increased to a certain extent, the extreme pressure performance will no longer be improved. Adding antifoaming agents is to improve the anti-foaming performance of the oil and prevent problems caused by excessive foaming. Adding too much will cause the oil to become cloudy and the antifoaming performance will fail. Adding demulsifiers is to enhance the anti-emulsification performance of the oil and ensure that the oil can maintain its properties in the presence of water. If the amount added is too low, the antifoaming performance will be poor, and if the amount added is too high, there will be no significant improvement.

[0051] In some specific embodiments, the thickener includes at least one of lithium stearate or 12-hydroxystearic acid;

[0052] And / or, the thickening temperature is 180–210°C (non-limiting examples such as 180°C, 195°C, 200°C, or 210°C, etc.), and the thickening time is 1–3 h (non-limiting examples such as 1 h, 1.5 h, 2 h, or 3 h, etc.).

[0053] Secondly, embodiments of the present invention also provide a lubricating grease, which is prepared by the preparation method described in the first aspect.

[0054] Thirdly, embodiments of the present invention also propose the application of the lubricating grease as described in the second aspect in a wind turbine generator.

[0055] The following are non-limiting embodiments and comparative examples of the present invention. It should be noted that the comparative examples are not prior art, but are only provided for comparison with the embodiments and are not intended to limit the present invention. Unless otherwise stated, all raw materials used in the embodiments and comparative examples are conventional commercially available products or can be prepared by known methods.

[0056] Example 1

[0057] This embodiment provides a method for preparing a lubricating grease, including the following steps:

[0058] S1. First, waste gear oil at 80℃ is passed into a sedimentation separator and allowed to settle for 180 minutes. Then, a plate and frame filter press is used to coarsely filter the settled waste gear oil (filter element pore size is 10μm) to remove large particles, large water droplets, or dust. Next, centrifugation is used to remove small suspended particles and water droplets from the waste gear oil. Then, the centrifuged waste gear oil is subjected to vacuum distillation at 180℃ and a vacuum degree below 0.09mPa to remove residual water. After vacuum distillation for 2 hours, the waste gear oil is further finely filtered using a bag filter (filter membrane pore size is 5μm) for 2 hours to remove residual impurities, resulting in finely filtered waste gear oil.

[0059] S2. Mix 70 parts by weight of finely filtered waste gear oil with 15 parts by weight of PAO base oil, 2.98 parts by weight of sulfurized isobutylene, 0.01 parts by weight of dimethyl silicone oil, and 0.01 parts by weight of propylene oxide / ethylene oxide copolymer. Then add 12 parts by weight of lithium stearate and stir until well mixed. Heat the mixture to 200°C for thickening treatment. After 2 hours, a true solution will appear. Cool the mixture to obtain the grease.

[0060] Upon testing, in step S1 of this embodiment, before the waste gear oil undergoes impurity removal treatment, the kinematic viscosity of the waste gear oil at 40°C is 264 mm⁻¹. 2 / s, cleanliness grade 12, anti-foaming properties 640 / 20, 420 / 10, 680 / 20, water content 540ppm, deemulsification performance >60min; while after impurity removal, the kinematic viscosity of the obtained finely filtered waste gear oil at 40℃ is 322mm. 2 / s, cleanliness level 8, anti-foaming performance 50 / 0, 20 / 0, 40 / 0, ​​moisture content 280ppm, deemulsification performance 20min.

[0061] Example 2

[0062] This embodiment provides a method for preparing a lubricating grease, including the following steps:

[0063] S1. First, waste gear oil at 80℃ is passed into a sedimentation separator and allowed to settle for 180 minutes. Then, a plate and frame filter press is used to coarsely filter the settled waste gear oil (filter element pore size is 10μm) to remove large particles, large water droplets, or dust. Next, centrifugation is used to remove small suspended particles and water droplets from the waste gear oil. Then, the centrifuged waste gear oil is subjected to vacuum distillation at 180℃ and a vacuum degree below 0.09mPa to remove residual water. After vacuum distillation for 2 hours, the waste gear oil is further finely filtered using a bag filter (filter membrane pore size is 5μm) for 2 hours to remove residual impurities, resulting in finely filtered waste gear oil.

[0064] S2. Mix 70 parts by weight of finely filtered waste gear oil with 15 parts by weight of PAO base oil, 2.98 parts by weight of sulfurized lard, 0.01 parts by weight of dimethyl silicone oil, and 0.01 parts by weight of propylene oxide / ethylene oxide copolymer. Then add 12 parts by weight of lithium stearate and stir until well mixed. Heat the mixture to 200°C for thickening treatment. After 2 hours, a true solution will appear. Cool the mixture to obtain the grease.

[0065] S2. Mix 70 parts by weight of finely filtered waste gear oil with 15 parts by weight of base oil and 3 parts by weight of additives evenly, then add 12 parts by weight of thickener and stir evenly. Heat to 200°C for thickening treatment. After 2 hours, a true solution appears. Cool down to obtain the grease.

[0066] Upon testing, in step S1 of this embodiment, before the waste gear oil undergoes impurity removal treatment, the kinematic viscosity of the waste gear oil at 40°C is 264 mm⁻¹. 2 / s, cleanliness grade 12, anti-foaming properties 640 / 20, 420 / 10, 680 / 20, water content 540ppm, deemulsification performance >60min; while after impurity removal, the kinematic viscosity of the finely filtered waste gear oil at 40℃ is 316mm. 2 / s, cleanliness level 8, anti-foaming performance 50 / 0, 20 / 0, 40 / 0, ​​moisture content 280ppm, deemulsification performance 20min.

[0067] Example 3

[0068] This embodiment provides a method for preparing a lubricating grease, including the following steps:

[0069] S1. First, waste gear oil at 80℃ is passed into a sedimentation separator and allowed to settle for 180 minutes. Then, a plate and frame filter press is used to coarsely filter the settled waste gear oil (filter element pore size is 10μm) to remove large particles, large water droplets, or dust. Next, centrifugation is used to remove small suspended particles and water droplets from the waste gear oil. Then, the centrifuged waste gear oil is subjected to vacuum distillation at 180℃ and a vacuum degree below 0.09mPa to remove residual water. After vacuum distillation for 2 hours, the waste gear oil is further finely filtered using a bag filter (filter membrane pore size is 5μm) for 2 hours to remove residual impurities, resulting in finely filtered waste gear oil.

[0070] S2. Mix 70 parts by weight of finely filtered waste gear oil with 15 parts by weight of PAO base oil, 0.98 parts by weight of sulfurized isobutylene, 0.01 parts by weight of dimethyl silicone oil, and 0.01 parts by weight of propylene oxide / ethylene oxide copolymer. Then add 12 parts by weight of lithium stearate and stir to mix evenly. Heat to 200°C for thickening treatment. After 2 hours, a true solution appears. Cool down to obtain the grease.

[0071] Upon testing, in step S1 of this embodiment, before the waste gear oil undergoes impurity removal treatment, the kinematic viscosity of the waste gear oil at 40°C is 264 mm⁻¹. 2 / s, cleanliness grade 12, anti-foaming properties 640 / 20, 420 / 10, 680 / 20, water content 540ppm, deemulsification performance >60min; while after impurity removal, the kinematic viscosity of the obtained finely filtered waste gear oil at 40℃ is 320mm. 2 / s, cleanliness level 8, anti-foaming performance 50 / 0, 20 / 0, 40 / 0, ​​moisture content 280ppm, deemulsification performance 20min.

[0072] Example 4

[0073] This embodiment provides a method for preparing a lubricating grease, including the following steps:

[0074] S1. First, waste gear oil at 80℃ is passed into a sedimentation separator and allowed to settle for 180 minutes. Then, a plate and frame filter press is used to coarsely filter the settled waste gear oil (filter element pore size is 10μm) to remove large particles, large water droplets, or dust. Next, centrifugation is used to remove small suspended particles and water droplets from the waste gear oil. Then, the centrifuged waste gear oil is subjected to vacuum distillation at 180℃ and a vacuum degree below 0.09mPa to remove residual water. After vacuum distillation for 2 hours, the waste gear oil is further finely filtered using a bag filter (filter membrane pore size is 5μm) for 2 hours to remove residual impurities, resulting in finely filtered waste gear oil.

[0075] S2. Mix 70 parts by weight of finely filtered waste gear oil with 5 parts by weight of PAO base oil, 2.98 parts by weight of sulfurized isobutylene, 0.01 parts by weight of dimethyl silicone oil, and 0.01 parts by weight of propylene oxide / ethylene oxide copolymer. Then add 12 parts by weight of 12-hydroxystearic acid and stir to mix evenly. Heat to 200°C for thickening treatment. After 2 hours, a true solution appears. Cool down to obtain the grease.

[0076] Upon testing, in step S1 of this embodiment, before the waste gear oil undergoes impurity removal treatment, the kinematic viscosity of the waste gear oil at 40°C is 264 mm⁻¹. 2 / s, cleanliness grade 12, anti-foaming properties 640 / 20, 420 / 10, 680 / 20, water content 540ppm, deemulsification performance >60min; while after impurity removal, the kinematic viscosity of the obtained finely filtered waste gear oil at 40℃ is 293mm. 2 / s, cleanliness level 8, anti-foaming performance 50 / 0, 20 / 0, 40 / 0, ​​moisture content 280ppm, deemulsification performance 20min.

[0077] Example 5

[0078] This embodiment provides a method for preparing a lubricating grease, including the following steps:

[0079] S1. First, waste gear oil at 80℃ is passed into a sedimentation separator and allowed to settle for 180 minutes. Then, a plate and frame filter press is used to coarsely filter the settled waste gear oil (filter element pore size is 10μm) to remove large particles, large water droplets, or dust. Next, centrifugation is used to remove small suspended particles and water droplets from the waste gear oil. Then, the centrifuged waste gear oil is subjected to vacuum distillation at 180℃ and a vacuum degree below 0.09mPa to remove residual water. After vacuum distillation for 2 hours, the waste gear oil is further finely filtered using a bag filter (filter membrane pore size is 5μm) for 2 hours to remove residual impurities, resulting in finely filtered waste gear oil.

[0080] S2. Mix 70 parts by weight of finely filtered waste gear oil with 20 parts by weight of PAO base oil, 2.98 parts by weight of sulfurized isobutylene, 0.01 parts by weight of dimethyl silicone oil, and 0.01 parts by weight of propylene oxide / ethylene oxide copolymer. Then add 12 parts by weight of 12-hydroxystearic acid and stir to mix evenly. Heat to 200°C for thickening treatment. After 2 hours, a true solution appears. Cool down to obtain the grease.

[0081] Upon testing, in step S1 of this embodiment, before the waste gear oil undergoes impurity removal treatment, the kinematic viscosity of the waste gear oil at 40°C is 264 mm⁻¹. 2 / s, cleanliness grade 12, anti-foaming properties 640 / 20, 420 / 10, 680 / 20, water content 540ppm, deemulsification performance >60min; while after impurity removal, the kinematic viscosity of the obtained finely filtered waste gear oil at 40℃ is 332mm. 2 / s, cleanliness level 8, anti-foaming performance 50 / 0, 20 / 0, 40 / 0, ​​moisture content 280ppm, deemulsification performance 20min.

[0082] Comparative Example 1

[0083] This comparative example provides a method for preparing a lubricating grease, comprising the following steps:

[0084] S1. First, waste gear oil at 80℃ is passed into a sedimentation separator and allowed to settle for 180 minutes. Then, a plate and frame filter press is used to coarsely filter the settled waste gear oil (filter element pore size is 10μm) to remove large particles, large water droplets, or dust. Next, centrifugation is used to remove small suspended particles and water droplets from the waste gear oil. Then, the centrifuged waste gear oil is subjected to vacuum distillation at 180℃ and a vacuum degree below 0.09mPa to remove residual water. After vacuum distillation for 2 hours, the waste gear oil is further finely filtered using a bag filter (filter membrane pore size is 5μm) for 2 hours to remove residual impurities, resulting in finely filtered waste gear oil.

[0085] S2, mix 70 parts by weight of finely filtered waste gear oil with 15 parts by weight of PAO base oil, 0.01 parts by weight of dimethyl silicone oil and 0.01 parts by weight of propylene oxide / ethylene oxide copolymer, add 12 parts by weight of lithium stearate and stir until well mixed, then heat to 200°C for thickening treatment. After 2 hours, a true solution appears. Cool down to obtain the grease.

[0086] According to the test results, in step S1 of this comparative example, before the waste gear oil underwent impurity removal treatment, the kinematic viscosity of the waste gear oil at 40°C was 264 mm⁻¹. 2 / s, cleanliness grade 12, anti-foaming properties 640 / 20, 420 / 10, 680 / 20, water content 540ppm, deemulsification performance >60min; while after impurity removal, the kinematic viscosity of the obtained finely filtered waste gear oil at 40℃ is 324mm. 2 / s, cleanliness level 8, anti-foaming performance 50 / 0, 20 / 0, 40 / 0, ​​moisture content 280ppm, deemulsification performance 20min.

[0087] Comparative Example 2

[0088] This comparative example provides a method for preparing a lubricating grease, comprising the following steps:

[0089] S1. First, waste gear oil at 80℃ is passed into a sedimentation separator and allowed to settle for 180 minutes. Then, a plate and frame filter press is used to coarsely filter the settled waste gear oil (filter element pore size is 10μm) to remove large particles, large water droplets, or dust. Next, centrifugation is used to remove small suspended particles and water droplets from the waste gear oil. Then, the centrifuged waste gear oil is subjected to vacuum distillation at 180℃ and a vacuum degree below 0.09mPa to remove residual water. After vacuum distillation for 2 hours, the waste gear oil is further finely filtered using a bag filter (filter membrane pore size is 5μm) for 2 hours to remove residual impurities, resulting in finely filtered waste gear oil.

[0090] S2, mix 70 parts by weight of finely filtered waste gear oil with 15 parts by weight of PAO base oil, add 12 parts by weight of lithium stearate and stir until well mixed, then heat to 200°C for thickening treatment. After 2 hours, a true solution appears. Cool down to obtain the grease.

[0091] According to the test results, in step S1 of this comparative example, before the waste gear oil underwent impurity removal treatment, the kinematic viscosity of the waste gear oil at 40°C was 264 mm⁻¹. 2 / s, cleanliness grade 12, anti-foaming properties 640 / 20, 420 / 10, 680 / 20, water content 540ppm, deemulsification performance >60min; while after impurity removal, the kinematic viscosity of the obtained finely filtered waste gear oil at 40℃ is 324mm. 2 / s, cleanliness level 8, anti-foaming performance 50 / 0, 20 / 0, 40 / 0, ​​moisture content 280ppm, deemulsification performance 20min.

[0092] Comparative Example 3

[0093] This comparative example provides a method for preparing a lubricating grease, comprising the following steps:

[0094] S1. First, waste gear oil at 80℃ is passed into a sedimentation separator and allowed to settle for 180 minutes. Then, a plate and frame filter press is used to coarsely filter the settled waste gear oil (filter element pore size is 10μm) to remove large particles, large water droplets, or dust. Next, centrifugation is used to remove small suspended particles and water droplets from the waste gear oil. Then, the centrifuged waste gear oil is subjected to vacuum distillation at 180℃ and a vacuum degree below 0.09mPa to remove residual water. After vacuum distillation for 2 hours, the waste gear oil is further finely filtered using a bag filter (filter membrane pore size is 5μm) for 2 hours to remove residual impurities, resulting in finely filtered waste gear oil.

[0095] S2, mix 70 parts by weight of finely filtered waste gear oil with 2.98 parts by weight of sulfurized isobutylene, 0.01 parts by weight of dimethyl silicone oil and 0.01 parts by weight of propylene oxide / ethylene oxide copolymer, add 12 parts by weight of lithium stearate and stir to mix evenly, then heat to 200°C for thickening treatment. After 2 hours, a true solution appears. Cool down to obtain the grease.

[0096] According to the test results, in step S1 of this comparative example, before the waste gear oil underwent impurity removal treatment, the kinematic viscosity of the waste gear oil at 40°C was 264 mm⁻¹. 2 / s, cleanliness grade 12, anti-foaming properties 640 / 20, 420 / 10, 680 / 20, water content 540ppm, deemulsification performance >60min; while after impurity removal, the kinematic viscosity of the obtained finely filtered waste gear oil at 40℃ is 322mm. 2 / s, cleanliness level 8, anti-foaming performance 50 / 0, 20 / 0, 40 / 0, ​​moisture content 280ppm, deemulsification performance 20min.

[0097] The performance of the wind turbine gear oil repair agents prepared in Examples 1-5 and Comparative Examples 1-3 of this invention was tested. The dropping point (the lowest temperature at which the lubricating grease begins to drip after melting when heated) was determined according to GB / T 4929, the oil separation volume was determined according to NB / SH / T 0324, and the extreme pressure performance was determined according to SH / T 0202. The test results are shown in Table 1.

[0098] Table 1

[0099]

[0100]

[0101] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0102] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a grease, characterized by, It comprises the following steps: S1, the waste gear oil is sequentially settled, coarsely filtered, centrifuged, distilled and finely filtered; wherein, the temperature of the waste gear oil is 60-100 DEG C during the settlement, and the settlement time is 120-180 min; the coarsely filtering adopts a plate and frame filter, and the pore size of the filter core used during the coarsely filtering is 5-10 μm; the temperature of the waste gear oil is 60-100 DEG C during the centrifuging; the instrument used in the fine filtering is a bag filter; the pore size of the filter membrane of the bag filter is 1-5 μm, and the circulating filtering time is 2-4 h; S2, after the waste gear oil after the fine filtering is mixed with base oil and additives, a thickening agent is added to carry out thickening treatment, and the grease is obtained; wherein, the weight fraction of the waste gear oil after the fine filtering is 70-95 parts, the weight fraction of the base oil is 1-20 parts, the weight fraction of the additives is 0.5-4 parts, and the weight fraction of the thickening agent is 8-15 parts; the base oil is a PAO base oil; the additives comprise at least one of 0.01-3 parts of extreme pressure anti-wear agent, 0.001-0.1 parts of anti-foaming agent and 0.001-0.1 parts of demulsifier; the extreme pressure anti-wear agent comprises at least one of sulfurized isobutylene or sulfurized lard oil.

2. The grease production method according to claim 1, characterized by, The distillation mode comprises at least one of reduced pressure distillation or molecular distillation; the distillation temperature is 160-200 DEG C, the vacuum degree is <0.09 mPa, and the distillation time is 2-4 h.

3. The grease production method according to claim 1, characterized by, The anti-foaming agent comprises at least one of dimethyl silicone oil, amino silicone oil or methacrylic acid; And / or, the demulsifier comprises at least one of hexanediol ester or polyether high molecular compound.

4. The grease production method according to claim 1, characterized by, The thickening agent comprises at least one of lithium stearate or 12-hydroxystearic acid; And / or, the thickening treatment temperature is 180-210 DEG C, and the thickening treatment time is 1-3 h.

5. The grease production method according to claim 1, characterized by, The 40°C kinematic viscosity of the waste gear oil is 256-384 mm 2 / s, cleanliness > 10 grade, anti-foam performance > 300 / 0, moisture content > 500 ppm, anti-emulsification performance > 60 min; and / or, the kinematic viscosity at 40°C of the refined waste gear oil is 288-352 mm 2 / s, cleanliness ≤ 8 class, anti-foam performance < 100 / 0, moisture content < 300 ppm, anti-emulsification performance < 30 min.

6. A grease, characterized by The grease is prepared by the preparation method in any one of claims 1-5.

7. The grease according to claim 6 for use in a wind turbine.

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