A lubricating grease for a main shaft bearing of a wind turbine and a method for producing the same

Abstract

This invention discloses a grease for the main shaft bearing of a wind turbine generator and its preparation method. The raw material ratio of the grease is as follows: base oil 76.33-81.04%; 12-hydroxystearic acid 6.5-7%; azelaic acid 2.01-2.2%; oil-based lithium hydroxide 2-2.7%; calcium hydroxide 0.32-0.82%; antioxidant 0.4-0.6%; rust inhibitor 3.03-5.05%; extreme pressure anti-wear agent is molybdenum dialkyl dithiocarbamate 2-3%; structure control agent is vinyl silicone oil 2-3%; and the thickener is a composite lithium-calcium thickener. The base oil is selected from synthetic PAO and metallocene PAO. The preparation method combining vinyl silicone oil with a gradient cooling process can effectively improve the grease structure, enhance its adhesion, water resistance, and shear stability. This invention can meet the lubrication requirements of the main shaft bearing of wind turbine generators and has good application prospects.

Description

Technical Field

[0001] This invention relates to a method for preparing bearing grease, and more particularly to a wind turbine main shaft bearing grease and its preparation method. Background Technology

[0002] As the core component supporting the rotation of a wind turbine generator, the main shaft is difficult to maintain and service. This places high demands on the lifespan and stability of the lubricant used in its bearings. Besides possessing low-temperature performance, corrosion and rust resistance, and extreme pressure anti-wear properties, the lubricant must also exhibit excellent adhesion and water resistance. Ensuring effective lubrication of the wind turbine main shaft bearings can, to a certain extent, determine the lifespan and performance of the wind turbine generator.

[0003] Based on the current analysis of wind turbine main bearing failures, especially for wind power grease prepared from synthetic base oil, the following problems exist: (1) The adhesion performance of the main shaft grease is poor. At room temperature, it can adhere to the bearing surface without being lost. However, under the high temperature conditions in summer, the viscosity retention becomes poor, and the grease is easy to be lost from the bearing gap, causing bearing lubrication failure; (2) Wind power equipment is generally located in remote areas, such as offshore and desert areas. Affected by the alternation of winter and summer, the ambient temperature is between -40℃ and 40℃. At the same time, it is also affected by wind, sand, rain, snow and salt spray. The water resistance is poor, which easily causes grease loss and bearing corrosion.

[0004] Chinese patent CN115058271A discloses a heavy-duty bearing grease and its preparation method, comprising the following components in the indicated weight ratios: 70.5% complex lithium-calcium grease, 13% thickener, 3% oiliness agent, 3% extreme pressure anti-wear agent, 0.5% antioxidant, and 10% graphite additive. The complex lithium-calcium grease is prepared by mixing 86.5% base oil, 8% dodecyl stearic acid, 3% azelaic acid, 2% lithium hydroxide, and 0.5% calcium hydroxide. By using the complex lithium-calcium grease as a thickener, the grease can be endowed with excellent anti-wear, extreme pressure, and water resistance properties. However, the preparation process of the composite lithium-calcium grease in this patent only uses base oil for rapid cooling, and the cooling process is simple, resulting in low viscosity of the grease. Therefore, a thickener needs to be added, and the amount of thickener reaches 13%. Although adding too much thickener can improve the viscosity and water resistance of the grease, the shear stability of the grease will decrease significantly, which will lead to the problem of the grease thinning and flowing away at high temperature. Summary of the Invention

[0005] Objective of this invention: The objective of this invention is to provide a grease for wind turbine main shaft bearings, addressing the problem that existing bearing greases cannot simultaneously achieve both adhesion and shear stability. Another objective of this invention is to propose a method for preparing this bearing grease, solving the problem of existing preparation processes relying on thickeners to improve the grease's viscosity and water resistance.

[0006] Technical solution: The wind turbine main shaft bearing grease of the present invention is made from the following raw materials in the indicated mass fractions: base oil 76.33-81.04%, 12-hydroxystearic acid 6.5-7.0%, azelaic acid 2.01-2.2%, oil-based lithium hydroxide 2-2.7%, calcium hydroxide 0.32-0.82%, vinyl silicone oil 2-3%, and additives 5.43-9.65%.

[0007] Preferably, the kinematic viscosity of the base oil at 40°C is 10-5000 mmHg. 2 / s; the kinematic viscosity of the vinyl silicone oil at 25°C is 50,000-200,000 mm³ / s. 2 / s. The vinyl silicone oil used in this invention is a high-viscosity vinyl silicone oil, which further helps to improve the adhesion of the grease.

[0008] Preferably, the base oil comprises polyalphaolefin and metallocene polyalphaolefin, and the kinematic viscosity of the base oil at 40°C is 140-460 mmHg. 2 / s; the kinematic viscosity of the vinyl silicone oil at 25°C is 80,000-120,000 mm³ / s. 2 / s. A base oil of appropriate viscosity is beneficial for gradient cooling operations in the preparation process, preventing excessively rapid cooling from reducing the structural improvement effect of the vinyl silicone oil.

[0009] Preferably, the kinematic viscosity of the polyalphaolefin at 40°C is 31-66 mmHg. 2 / s; the kinematic viscosity of the metallocene polyalphaolefin at 40°C is 3000-4000 mm³ / s. 2 / s.

[0010] Preferably, the polyalphaolefin is selected from PAO6, PAO8, or PAO10; the metallocene polyalphaolefin is mPAO300, with a kinematic viscosity of 3350 mmHg at 40°C. 2 / s.

[0011] Preferably, the additive consists of 0.4-0.6% antioxidant, 3.03-6.05% rust inhibitor and 2-3% extreme pressure anti-wear agent by weight of raw materials; the antioxidant is a mixture of amine antioxidant and phenolic antioxidant; and the lithium hydroxide content in the oil-based lithium hydroxide is not less than 36.3 wt%.

[0012] Preferably, the extreme pressure anti-wear agent is molybdenum dialkyldithiocarbamate; the rust inhibitor is benzotriazole or zinc naphthenate; the amine antioxidant is alkyl diphenylamine T-534, and the phenolic antioxidant is L5135.

[0013] To prepare the aforementioned grease for the main shaft bearing of a wind turbine generator, the present invention provides the following preparation method, comprising the following steps:

[0014] (1) The base oil is prepared by mixing polyalphaolefin and metallocene polyalphaolefin. The base oil, not exceeding 50 wt% of the total amount of base oil, is added to the reactor, and then 12-hydroxystearic acid is added and heated until all the materials are dissolved.

[0015] (2) Add calcium hydroxide aqueous solution dropwise into the reaction vessel and heat and stir to react;

[0016] (3) Add a portion of oil-based lithium hydroxide dropwise to the reaction vessel and heat and stir to react;

[0017] (4) Add azelaic acid and the remaining oil-based lithium hydroxide to the reactor, heat and stir to react; after heating and dehydration, take a sample to measure the free alkali, control the free alkali content at 0.05-0.15%, continue to heat to 220-230℃ and hold for 3-5 minutes, add 15-25wt% of the total base oil, cool rapidly to 170-190℃, add vinyl silicone oil and stir for 0.3-1 hour.

[0018] (5) Add the remaining base oil and gradually cool it to 140-150℃. After homogenization, add the additives and mix well to obtain the grease.

[0019] The preparation method provided by this invention uses a portion of high-viscosity SpectraSyn Elite. TM Metallocene polyalphaolefin mPAO300 base oil formulated grease, high viscosity SpectraSyn Elite TM The grease formulated with metallocene polyalphaolefin mPAO300 base oil has high adhesion and excellent water resistance. By adding vinyl silicone oil, a structure control agent, at a specific temperature, the vinyl silicone oil is combined with a composite lithium-calcium thickener at high temperature. Under special processes, the structure of the grease is improved, effectively enhancing its water resistance.

[0020] Preferably, the method of adding the remaining base oil and gradually cooling to 140-150℃ in step (5) is as follows: add the remaining base oil and continue cooling to 140-150℃. The gradient cooling process can help vinyl silicone oil improve the structure of the grease, increase the adhesion of the grease, and thus improve the water resistance, while eliminating the need for adding a thickener.

[0021] Preferably, the heating temperature in step (1) is controlled at 85-90℃; the heating temperature in step (2) is controlled at 105-115℃, and the stirring time is 0.2-1h; the heating temperature in step (3) is controlled at 105-115℃, and the stirring time is 1.5-2h; the heating temperature in step (4) is controlled at 120-130℃, and the stirring time is 1.5-2h; the temperature for heating and dehydration is controlled at 140-150℃, and the temperature is raised to 220-230℃ and kept constant for 3-5 minutes; the temperature for adding vinyl silicone oil is between 170-190℃, and the time is 3 minutes; after the gradient cooling in step (5), all materials are transferred to an intermediate reactor, circulated and sheared for 1-3 hours, and then homogenized.

[0022] Beneficial Effects: Compared with existing technologies, the present invention has the following significant advantages: The grease prepared by the present invention has good shear stability, adhesion properties, and water resistance, preventing the grease viscosity from deteriorating under high-temperature conditions in summer; and it also addresses insufficient water resistance under humid conditions, thus meeting the lubrication requirements of wind turbine main shaft bearings. The grease preparation method in the present invention effectively improves the grease structure, enabling the product to possess both good adhesion and high-temperature shear stability without the need for thickeners. The preparation method is simple and reliable, and has good application prospects. Detailed Implementation

[0023] The technical solution of the present invention will be further described below.

[0024] Example 1: The raw material dosage and preparation method of the lubricating grease for the main shaft bearing of a wind turbine are as follows:

[0025] (1) Mix 1600 kg of polyalphaolefin (PAO6) with 2452 kg of SpectraSyn Elite TM Metallocene polyalphaolefin (mPAO300) was mixed evenly and used as a base oil. The kinematic viscosity of polyalphaolefin at 40°C was 31 mm. 2 The kinematic viscosity of metallocene polyalphaolefin at 40°C is 3350 mm² / s. 2 / s, the kinematic viscosity of the base oil at 40°C is 140 mm⁻¹ 2 / s; 1500 kg of base oil was fed into the reactor through a 1 μm bag filter, followed by 325 kg of 12-hydroxystearic acid, which was heated to 85 °C until completely dissolved.

[0026] (2) Dissolve 16 kg of calcium hydroxide completely in 48 kg of deionized water and slowly add it dropwise into the reactor, while controlling the temperature at 100℃ and stirring for 0.5 h.

[0027] (3) Next, 70 kg of oil-based lithium hydroxide was slowly added dropwise to the reactor, and the temperature was controlled at 105℃. The mixture was stirred for 1.5 h. After that, 100.5 kg of azelaic acid was added and the temperature was raised to 120℃. The remaining 55 kg of oil-based lithium hydroxide was slowly added to the reaction and stirred for 1 h. The temperature was then raised to 140℃ for dehydration. After dehydration, a sample was taken to measure the free alkali content. The free alkali content was controlled at 0.05-0.15%. Then the temperature was raised to 220℃ for high-temperature refining for 3 min.

[0028] (4) Slowly add 1000 kg of base oil, rapidly cool to 170°C, add 100 kg of structure control agent vinyl silicone oil and stir at a constant temperature for 30 minutes, then add the remaining base oil and continue to cool naturally to 140°C. The kinematic viscosity of vinyl silicone oil at 25°C is 50000 mm³ / s. 2 / s.

[0029] (5) Transfer to intermediate reactor, circulate and shear filter for 2 hours, and after homogenization, add in sequence a mixture of antioxidant 10kg alkyl diphenylamine T-534 and 10kg phenolic antioxidant L5135; a mixture of rust inhibitor 1.5kg T706 and 150kg T704; and 100kg extreme pressure anti-wear agent P1002A. Stir evenly, degas, and filter through a 200-mesh stainless steel filter to obtain the finished product.

[0030] Example 2: The raw material dosage and preparation method of the lubricating grease for the main shaft bearing of a wind turbine are as follows:

[0031] (1) Mix 1150 kg of polyalphaolefin (PAO6) with 2788 kg of SpectraSyn Elite TM Metallocene polyalphaolefin (mPAO300) was mixed evenly and used as a base oil. The kinematic viscosity of polyalphaolefin at 40°C was 31 mm. 2 The kinematic viscosity of metallocene polyalphaolefin at 40°C is 3350 mm² / s. 2 / s, the kinematic viscosity of the base oil at 40°C is 460 mm⁻¹. 2 / s; 1500 kg of base oil was fed into the reactor through a 1 μm bag filter, followed by 337.5 kg of 12-hydroxystearic acid, which was heated to 87.5 °C until completely dissolved.

[0032] (2) Dissolve 27.5 kg of calcium hydroxide completely in 82.5 kg of deionized water and slowly add it dropwise into the reactor, while controlling the temperature at 102.5℃ and stirring for 0.2 h.

[0033] (3) Then, 70 kg of oil-based lithium hydroxide was slowly added dropwise to the reactor, and the temperature was controlled at 110°C. After 2 hours, 100.5 kg of azelaic acid was added and the temperature was raised to 125°C. The remaining 45 kg of oil-based lithium hydroxide was slowly added and stirred for 1.5 hours. The temperature was then raised to 145°C for dehydration. After dehydration, a sample was taken to measure the free alkali content, which was controlled at 0.05-0.15%. Then, the temperature was raised to 225°C for high-temperature refining for 5 minutes.

[0034] (4) Slowly add 1000 kg of base oil, rapidly cool to 180°C, add 125 kg of structure control agent vinyl silicone oil and stir at a constant temperature for 60 minutes, then add the remaining base oil and continue to cool naturally to 145°C. The kinematic viscosity of vinyl silicone oil at 25°C is 200,000 mm³ / h. 2 / s.

[0035] (5) Transfer to intermediate reactor, circulate and shear filter for 3 hours, and after homogenization, add in sequence a mixture of antioxidant 12.5 kg alkyl diphenylamine T-534 and 12.5 kg phenolic antioxidant L5135; a mixture of rust inhibitor 2 kg T706 and 200 kg T704; and 125 kg extreme pressure anti-wear agent P1002A. Stir evenly, degas, and filter through a 200-mesh stainless steel filter to obtain the finished product.

[0036] Example 3: The raw material dosage and preparation method of the lubricating grease for the main shaft bearing of a wind turbine are as follows:

[0037] (1) Mix 1200 kg of polyalphaolefin (PAO8) with 2616.5 kg of SpectraSyn Elite TM Metallocene polyalphaolefin (mPAO300) was mixed evenly and used as a base oil. The kinematic viscosity of polyalphaolefin at 40°C was 48 mmHg. 2 The kinematic viscosity of metallocene polyalphaolefin at 40°C is 3350 mm² / s. 2 / s, the kinematic viscosity of the base oil at 40℃ is 306 mm⁻¹. 2 / s; 1500 kg of base oil is fed into the reactor through a 1 μm bag filter, followed by 350 kg of 12-hydroxystearic acid, and the temperature is raised to 85-90 °C until it is completely dissolved.

[0038] (2) Dissolve 41 kg of calcium hydroxide completely in 123 kg of deionized water and slowly add it dropwise into the reactor, while controlling the temperature at 105℃ and stirring for 1 hour.

[0039] (3) Then, 70 kg of oil-based lithium hydroxide was slowly added dropwise to the reactor, and the temperature was controlled at 115°C. After 1.5 h, 110 kg of azelaic acid was added and the temperature was raised to 130°C. The remaining 30 kg of oil-based lithium hydroxide was slowly added and stirred for 1 h. The temperature was then raised to 150°C for dehydration. After dehydration, a sample was taken to measure the free alkali. The free alkali content was controlled at 0.05-0.15%. Then the temperature was raised to 230°C for high-temperature refining for 4 min.

[0040] (4) Slowly add 1000 kg of base oil, rapidly cool to 190°C, add 150 kg of structure control agent vinyl silicone oil and stir at a constant temperature for 30 minutes, then add the remaining base oil and continue to cool naturally to 150°C. The kinematic viscosity of vinyl silicone oil at 25°C is 80000 mm³ / s. 2 / s.

[0041] (5) Transfer to intermediate reactor, circulate and shear filter for 2 hours, and after homogenization, add in sequence a mixture of antioxidant 15kg alkyl diphenylamine T-534 and 15kg phenolic antioxidant L5135; a mixture of rust inhibitor 2.5kg T706 and 250kg T704; and 150kg extreme pressure anti-wear agent P1002A. Stir evenly, degas, and filter through a 200-mesh stainless steel filter to obtain the finished product.

[0042] Example 4: The raw material dosage and preparation method of the lubricating grease for the main shaft bearing of a wind turbine are as follows:

[0043] (1) Mix 1200 kg of polyalphaolefin (PAO10) with 2552 kg of SpectraSyn Elite TM Metallocene polyalphaolefin (mPAO300) was mixed evenly and used as a base oil. The kinematic viscosity of polyalphaolefin at 40°C was 66 mmHg. 2 The kinematic viscosity of metallocene polyalphaolefin at 40°C is 4000 mm³ / s. 2 / s, the kinematic viscosity of the base oil at 40°C is 380 mm⁻¹ 2 / s; 1500 kg of base oil is fed into the reactor through a 1 μm bag filter, followed by 325 kg of 12-hydroxystearic acid, which is then heated to 85-90 °C until completely dissolved.

[0044] (2) Dissolve 25 kg of calcium hydroxide completely in 75 kg of deionized water and slowly add it dropwise into the reactor, while controlling the temperature at 100-105℃ and stirring for 1 hour.

[0045] (3) Then, 70 kg of oil-based lithium hydroxide was slowly added dropwise to the reactor, and the temperature was controlled at 115°C. After 2 hours, 100.5 kg of azelaic acid was added and the temperature was raised to 130°C. The remaining 55 kg of oil-based lithium hydroxide was slowly added and stirred for 1 hour. The temperature was then raised to 150°C for dehydration. After dehydration, a sample was taken to measure the free alkali content, which was controlled at 0.05-0.15%. Then, the temperature was raised to 230°C for high-temperature refining for 5 minutes.

[0046] (4) Slowly add 1000 kg of base oil, rapidly cool to 190°C, add 110 kg of structure control agent vinyl silicone oil and stir at a constant temperature for 18 minutes, then add the remaining base oil and continue to cool naturally to 145°C. The kinematic viscosity of vinyl silicone oil at 25°C is 120,000 mm³ / s. 2 / s.

[0047] (5) Transfer to intermediate reactor, circulate and shear filter for 1 hour, and after homogenization, add in sequence a mixture of 11 kg alkyl diphenylamine T-534 and 11 kg phenolic antioxidant L5135; a mixture of 2 kg T706 and 200 kg T704 as rust inhibitor; and 120 kg extreme pressure anti-wear agent P1002A. Stir evenly, degas, and filter through a 200-mesh stainless steel filter to obtain the finished product.

[0048] Comparative Example 1: Everything else was the same as in Example 3, except that the kinematic viscosity of the mixed base oil at 40°C was 100 mm. 2 / s.

[0049] Comparative Example 2: Everything else was the same as in Example 3, except that the kinematic viscosity of the mixed base oil at 40°C was 500 mmHg. 2 / s.

[0050] Comparative Example 3: Everything else is the same as in Example 3, except that the kinematic viscosity of the vinyl silicone oil at 25°C is 2000 mm. 2 / s.

[0051] Comparative Example 4: The rest is the same as Example 3, except that 1000 kg of base oil is slowly added in step (5) and the temperature is controlled to be rapidly cooled to 160°C.

[0052] Comparative Example 5: The rest is the same as Example 3, except that 1000 kg of base oil is slowly added in step (5) and the temperature is controlled to be rapidly cooled to 200°C.

[0053] Comparative Example 6: The rest is the same as Example 3, except that: in step (5), no gradient cooling is performed, and all the remaining base oil is added directly and cooled directly to 150°C.

[0054] Comparative Example 7: The rest is the same as in Example 3, except that vinyl silicone oil is replaced with methyl silicone oil.

[0055] Comparative Example 8: The rest is the same as Example 3, except that vinyl silicone oil is not added and base oil is used instead of vinyl silicone oil.

[0056] The bearing grease samples prepared in Examples 1-4 and Comparative Examples 1-8 were subjected to various physicochemical property tests, and the results are as follows:

[0057]

[0058]

[0059]

[0060] As can be seen from the data in Table 1:

[0061] The data on water resistance, water leaching loss, and adhesion of the greases in Comparative Examples 1-8 are all inferior to those in Examples 1-4. A comparison of Example 3 with Comparative Examples 1 and 2 shows that both excessively low and excessively high base oil viscosity negatively impact the water resistance, water leaching loss, and adhesion of the grease product. A comparison of Example 3 with Comparative Example 3 shows that lower viscosity vinyl silicone oil also leads to a decrease in the product's water resistance, water leaching loss, and adhesion. A comparison of Example 3 with Comparative Examples 4 and 5 shows that excessively low or high quenching temperatures in the preparation process hinder the improvement of the grease structure by the vinyl silicone oil. A comparison of Example 3 with Comparative Examples 6 and 8 shows that the gradient cooling step is a key step in the preparation process. The gradient cooling step effectively works in conjunction with the vinyl silicone oil to improve the grease structure. The vinyl silicone oil relies on the gradient cooling step to exert its structural improvement effect; without the vinyl silicone oil, the gradient cooling step cannot achieve the same structural improvement effect. The absence of either step ultimately fails to improve the grease's water resistance and shear stability. The comparison between Example 3 and Comparative Example 7 shows that, under the same viscosity conditions, the choice of modified silicone oil is also crucial. Different types of modified silicone oils have vastly different effects on improving the structure of the grease. Through preliminary exploratory experiments, the applicant found that vinyl silicone oil has a better effect on improving the structure in the preparation system of this invention.

Claims

1. A grease for the main shaft bearing of a wind turbine generator, characterized in that, It is prepared from the following raw materials in the indicated mass fractions: base oil 76.33-81.04%, 12-hydroxystearic acid 6.5-7.0%, azelaic acid 2.01-2.2%, oil-based lithium hydroxide 2-2.7%, calcium hydroxide 0.32-0.82%, vinyl silicone oil 2-3%, and additives 5.43-9.65%. The kinematic viscosity of the vinyl silicone oil at 25°C is 50,000-200,000 mm. 2 / s; The base oil is a mixture of polyalphaolefin and metallocene polyalphaolefin, and the kinematic viscosity of the base oil at 40°C is 140-460 mmHg. 2 / s; The method for preparing the grease for the main shaft bearing of the wind turbine includes the following steps: (1) The base oil is prepared by mixing polyalphaolefin and metallocene polyalphaolefin. The base oil, not exceeding 50 wt% of the total amount of base oil, is added to the reactor, and then 12-hydroxystearic acid is added and heated until all the materials are dissolved. (2) Add calcium hydroxide aqueous solution dropwise into the reaction vessel and heat and stir to react; (3) Add a portion of oil-based lithium hydroxide dropwise to the reaction vessel and heat and stir to react; (4) Add azelaic acid and the remaining oil-based lithium hydroxide to the reactor, heat and stir to react; after heating and dehydration, take a sample to measure the free alkali, control the free alkali content at 0.05-0.15%, continue to heat to 220-230℃ for high-temperature refining for 3-5 minutes, add 15-25wt% of the total base oil, cool rapidly to 170-190℃, add vinyl silicone oil and stir for 0.3-1 hour; (5) Add the remaining base oil and gradually cool it to 140-150℃. After homogenization, add the additives and mix well to obtain the grease.

2. The grease for the main shaft bearing of a wind turbine generator according to claim 1, characterized in that, The kinematic viscosity of the polyalphaolefin at 40°C is 31-66 mm. 2 / s; the kinematic viscosity of the metallocene polyalphaolefin at 40°C is 3350 mm⁻¹. 2 / s.

3. The wind turbine main shaft bearing grease according to claim 2, characterized in that, The polyalphaolefin is selected from one of PAO6, PAO8 or PAO10, and the metallocene polyalphaolefin is mPAO300.

4. The grease for the main shaft bearing of a wind turbine generator according to claim 1, characterized in that, The additive consists of 0.4-0.6% antioxidant, 3.03-6.05% rust inhibitor and 2-3% extreme pressure anti-wear agent by weight of raw materials; the antioxidant is a mixture of amine antioxidant and phenolic antioxidant; the lithium hydroxide content in the oil-based lithium hydroxide is not less than 36.3 wt%.

5. The wind turbine main shaft bearing grease according to claim 4, characterized in that, The extreme pressure anti-wear agent is molybdenum dialkyldithiocarbamate; the rust inhibitor is benzotriazole or zinc naphthenate; the amine antioxidant is alkyl diphenylamine T534, and the phenolic antioxidant is L5135.

6. The grease for the main shaft bearing of a wind turbine generator according to claim 1, characterized in that, The heating temperature in step (1) is controlled at 85-90℃; the heating temperature in step (2) is controlled at 105-115℃, and the stirring time is 0.2-1h; the heating temperature in step (3) is controlled at 105-115℃, and the stirring time is 1.5-2h; the heating temperature in step (4) is controlled at 120-130℃, and the stirring time is 1.5-2h; the temperature for heating and dehydration is controlled at 140-150℃, and high-temperature refining is carried out at 220-230℃ for 3-5 minutes; the temperature for adding vinyl silicone oil is between 170-190℃, and stirring is carried out for 0.3-1h; after the gradient cooling in step (5), all materials are transferred to the intermediate kettle, and the circulating shearing and filtration is carried out for 1-3h before homogenization.

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