Low-hardness bubble-free fluorosilicone compound material and preparation method thereof

Abstract

The application discloses a kind of low hardness bubble-free fluorosilicone mixing rubber material and preparation method thereof, belong to fluorosilicone mixing rubber field, a kind of low hardness bubble-free fluorosilicone mixing rubber material and preparation method thereof, the method uses low vinyl fluorosilicone raw rubber and methyl perfluoro raw rubber compound, and adopts base glue two-step method, methyl perfluoro raw rubber is added by temperature reduction, first with high stable system complete filler dispersion, reduce early kneading gas wrapping, then gradient viscosity reduction reaches ultra-low hardness, reduce gas content from source;With vacuum devolatilization, multiple thin pass and vulcanization subsection exhaust, whole process blocks bubble production path.Finally realize vulcanized product bubble-free, no pinhole, section dense, hardness is stable in shao A 10-30 degree, while keeping fluorosilicone rubber excellent medium resistance, low temperature flexibility and air tightness, processing process is stable, batch consistency is high, suitable for industrialized continuous production.

Description

Technical Field

[0001] This invention relates to the field of fluorosilicone compound, and more specifically, to a low-hardness, bubble-free fluorosilicone compound material and its preparation method. Background Technology

[0002] Fluorosilicone rubber combines high and low temperature resistance, oil and media resistance, weather resistance, and low compression set, making it widely used in soft sealing, cushioning, and micro-adhesion sealing applications in aerospace, automotive, semiconductor, and precision instruments. There is a strong demand for ultra-low hardness fluorosilicone compounds with Shore A hardness of 10A-30A. However, lower hardness means lower system viscosity and fewer fillers, making it easier for air to get trapped during mixing and for bubbles to form during vulcanization, posing a common technical challenge in the industry.

[0003] For example, Chinese patent application No. CN202010856645.0 filed on August 24, 2020 discloses a fluorosilicone compound and its preparation method. The method involves vacuum kneading fluorosilicone raw rubber, hydroxyl fluorosilicone oil, polyvinyl fluorosilicone oil, and modified silica in one step, then adding a vulcanizing agent to obtain a fluorosilicone compound; finally, a two-stage vulcanization is used to obtain the target fluorosilicone compound. However, this method has the following disadvantages: (1) Single matrix: Single fluorosilicone raw rubber cannot take into account both processing viscosity and final low hardness (for example, the compound prepared by this patent document has a minimum hardness of 42 Shore A and a maximum elongation of 481%). It is either too hard in the early stage and encapsulates air, or too soft and difficult to disperse fillers; (2) One-step mixing is seriously encapsulated: The hardness / viscosity of the system changes drastically throughout the process. The high shear kneading in the early stage forcibly encapsulates a large amount of air, which is difficult to expel in the later stage; (3) No gradient viscosity reduction design: It is impossible to reduce the hardness steadily while ensuring the dispersion of fillers. Gas is easily encapsulated inside the rubber compound; (4) Relying on post-treatment to suppress bubbles: It does not control the encapsulation and volatile matter from the mixing source. In addition, relying solely on vulcanization to degas is not a fundamental solution, and the bubble defect rate is high; (5) Poor consistency of low hardness: It relies on additives to reduce hardness. The batch fluctuations are large, and it is difficult to stably control the hardness.

[0004] Therefore, it is necessary to provide a fluorosilicone compound that can meet the requirements of low hardness and no bubbles. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a low-hardness, bubble-free fluorosilicone compound material and its preparation method. It uses vinyl polymethyltrifluoropropylsiloxane raw rubber as the main matrix, which is first kneaded at high temperature to ensure system stability, filler dispersion, and reduced gas entrainment. After the system cools down, polymethyltrifluoropropylsiloxane raw rubber is added to achieve gradient viscosity reduction, smoothly reaching a Shore A of 10-30 degrees Celsius. Combined with vacuum devolatilization, thin-pass degassing, and segmented degassing during vulcanization, the bubble problem is completely solved.

[0006] To solve the above problems, the present invention adopts the following technical solution.

[0007] A low-hardness, bubble-free fluorosilicone compound material, by weight, comprises 70-85 parts of vinyl polymethyl trifluoropropylsiloxane raw rubber (hereinafter referred to as low vinyl fluorosilicone raw rubber), 20-27 parts of fumed silica, 5-9 parts of hydroxyl fluorosilicone oil, 1-2 parts of cerium oxide, 2-5 parts of silazane, 0.1-0.3 parts of internal release agent, and 15-30 parts of polymethyl trifluoropropylsiloxane raw rubber (hereinafter referred to as methyl perfluoro raw rubber); and 1-2% of peroxide vulcanizing agent by weight of the above components.

[0008] Furthermore, the vinyl polymethyltrifluoropropylsiloxane raw rubber has a vinyl molar fraction of 0.08%-0.1% and a molecular weight of 800,000-1,500,000.

[0009] Furthermore, the molecular weight of the polymethyltrifluoropropylsiloxane raw rubber is 800,000 to 1,500,000.

[0010] Furthermore, the internal release agent is zinc stearate, stearic acid, calcium stearate, or aluminum stearate. Zinc stearate is preferred.

[0011] Furthermore, the peroxide vulcanizing agent is benzoyl peroxide, bis(2,4-dichlorobenzoyl peroxide), 2,5-dimethyl-2,5-bis-(tert-butylperoxy)-hexane, or dicumyl peroxide. Preferably, it is bis(2,4-dichlorobenzoyl peroxide), 2,5-dimethyl-2,5-bis-(tert-butylperoxy)-hexane, or dicumyl peroxide.

[0012] Furthermore, the specific surface area of ​​fumed silica is 200-300 m² / g. 2 / g; the particle size of cerium oxide is 50-70nm.

[0013] The present invention also provides a method for preparing the above-mentioned low-hardness, bubble-free fluorosilicone compound material, wherein the preparation steps are as follows: S1: Powder kneading stage: Put the vinyl polymethyltrifluoropropylsiloxane raw rubber into a vacuum kneader, heat and stir, then add fumed silica, hydroxyl fluorosilicone oil, silazane, cerium oxide and internal release agent in sequence, and knead by heating. S2: Heating and Vacuum Stage: After kneading the material from step S1, heat and knead it again, then keep it warm and degas it under vacuum. Then cool down and reduce the frequency, degas it under vacuum again, and add polymethyltrifluoropropylsiloxane raw rubber for a second kneading. S3: Vulcanization molding stage: The material obtained after the second kneading in step S2 and the peroxide vulcanizing agent are kneaded on a two-roll mill, and then placed in a flat vulcanizing machine for vulcanization to obtain a low-hardness, bubble-free fluorosilicone compound material.

[0014] Furthermore, in step S1, the fumed silica is added in two parts. The first part is added together with hydroxyl fluorosilicone oil, silazane, cerium oxide and internal release agent, and the amount added in the first part is 60-72% of the total mass of fumed silica. The second part is added after kneading until it forms a ball.

[0015] Furthermore, in step S1, the stirring temperature is 50-90℃ and the stirring time is 10-20 min; the temperature is raised to 80-90℃ and kneaded at 35-50 Hz for 1-2 h.

[0016] Furthermore, in step S2, the specific operation of heating and kneading is as follows: the material kneaded in step S1 is heated to 100-130℃ and kneaded at 30-40Hz for 0.5-1h, and then heated again to 140-160℃ and kneaded at 30-40Hz for 0.5-1.5h, preferably 0.5-1h.

[0017] Furthermore, in step S2, the vacuum degree is maintained at -0.05 to -0.08 MPa during the vacuum degassing process, and the degassing time is 1-2 hours; the specific operation of cooling and frequency reduction is as follows: turn off the heating and slowly cool down, while reducing the frequency to 10-25 Hz; the vacuum degree is maintained at -0.05 to -0.08 MPa during the secondary vacuum degassing process, and the secondary vacuum degassing time is 0.5-2 hours.

[0018] Furthermore, the secondary kneading time is 30-60 minutes, and the vacuum degree is maintained at -0.05 to -0.08 MPa during the kneading process.

[0019] Furthermore, the roll gap of the two-roll open mill is 0.5-1.1mm, the thin pass is 8-12 times, and the air is vented by forming a triangular bag; the vulcanization temperature is 170-180℃, and the vulcanization time is 300-600s.

[0020] Furthermore, during the vulcanization molding process, the air is vented 2-3 times in stages.

[0021] Compared with the prior art, the advantages of this invention are: I. This scheme involves compounding low-vinyl fluorosilicone raw rubber with methyl perfluorinated raw rubber and using a two-step method for the base rubber and a cooling method for adding methyl perfluorinated raw rubber to stably prepare ultra-low hardness fluorosilicone compound with a Shore A hardness of 10A-30A.

[0022] Second, this solution reduces the amount of gas trapped in the kneading process at the source, thus improving the efficiency of gas extraction during mixing. At the same time, the process is stable and controllable, making it suitable for industrial mass production.

[0023] Third, the material prepared by this method after vulcanization is free of bubbles and pinholes, has a dense cross-section, and excellent air tightness. Attached Figure Description

[0024] Figure 1 This is a flowchart of the preparation process for Example 1. Detailed Implementation

[0025] The low-vinyl fluorosilicone raw rubber involved in this application is commercially available, such as TPD-FS-EH2000 from Taipuda New Materials Co., Ltd.; the methyl perfluorinated raw rubber is commercially available, such as TPD-FS-ER1100 from Taipuda New Materials Co., Ltd.

[0026] Example 1:

[0027] like Figure 1 As shown, the preparation steps of the low-hardness, bubble-free fluorosilicone compound material of this scheme are as follows: (1) Kneading stage (only low vinyl fluorosilicone raw rubber is added) First, weigh 750g of low-vinyl fluorosilicone raw rubber (vinyl content 0.08%, molecular weight 950,000) into a 5L vacuum kneader and stir at 80℃ for 20 minutes. Then, add 250g of fumed silica (specific gravity 200m) sequentially. 2 (g), added in two batches. The first batch is 150g along with 60g hydroxyfluorosilicone oil, 26g silazane, 15g cerium oxide and 2g zinc stearate. After 20 minutes, when the mixture forms a ball, add another 100g and knead at 90℃ and 50Hz for 1 hour.

[0028] (2) Heating, vacuum stage The mixture was heated to 120℃ and kneaded at 35Hz for 1 hour, then heated to 155℃ and kneaded at 35Hz for another hour. The temperature and frequency were then maintained, and the mixture was vacuum degassed for 1 hour at a vacuum level of -0.06 MPa. Finally, the heating was turned off, the frequency was reduced to 15Hz, and vacuum degassed again until the temperature dropped to approximately 95℃. 250g of methyl perfluorinated raw rubber (molecular weight 950,000) was added, and kneading continued for 30 minutes (vacuum level maintained at -0.06 MPa) to obtain the fluorosilicone compound. Purpose: Gradual viscosity reduction, smoothly lowering the system hardness to the target range, and avoiding sudden viscosity changes that could lead to gas entrapment.

[0029] (3) Open mill vulcanization molding: Take 100g of fluorosilicone compound and 1g of bis(2,5) vulcanizing agent and repeatedly mill them evenly on a two-roll open mill (roll gap of open mill 0.5-1.1mm, thin pass 8-12 times, and make triangular bags to fully vent), and vulcanize at 175℃ for 300s in a flat vulcanizing machine (close the mold and vent in sections 2-3 times) to obtain fluorosilicone compound sample.

[0030] Example 2:

[0031] (1) Kneading and mixing stage First, weigh 750g of low-vinyl fluorosilicone raw rubber (vinyl content 0.08%, molecular weight 950,000) into a 5L vacuum kneader and stir at 80℃ for 20 minutes. Then, add 250g of fumed silica (specific gravity 200m) sequentially. 2 / g, added in two batches. The first batch consists of 150g added along with the additives. After 20 minutes of agglomeration, another 100g is added. 60g of hydroxyl fluorosilicone oil, 26g of silazane, 15g of cerium oxide, and 2g of zinc stearate as an internal release agent are added. Knead at 90℃ and 50Hz for 1 hour.

[0032] (2) Heating, vacuum stage The mixture was heated to 120℃ and kneaded at 35Hz for 1 hour, then heated to 155℃ and kneaded at 35Hz for another hour. The temperature and frequency were then maintained constant, and the mixture was vacuum degassed for 1 hour at a vacuum level of -0.06 MPa. Finally, heating was stopped, the frequency was reduced to 15Hz, and vacuum degassed again until the temperature dropped to approximately 95℃. 150g of methyl perfluorinated raw rubber (molecular weight 950,000) was added, and kneading continued for 30 minutes (vacuum level maintained at -0.06 MPa) to obtain the fluorosilicone compound. Purpose: Gradual viscosity reduction, smoothly lowering the system hardness to the target range, and avoiding sudden viscosity changes that could lead to gas entrapment.

[0033] (3) Open mill vulcanization molding: Take 100g of fluorosilicone compound and 1g of bis(2,5) vulcanizing agent and repeatedly mill them evenly on a two-roll open mill (roll gap of open mill 0.5-1.1mm, thin pass 8-12 times, and make triangular bags to fully vent), and vulcanize at 175℃ for 300s in a flat vulcanizing machine (close the mold and vent in sections 2-3 times) to obtain fluorosilicone compound sample.

[0034] Example 3:

[0035] (1) Kneading and mixing stage First, weigh 750g of low-vinyl fluorosilicone raw rubber (vinyl content 0.08%, molecular weight 950,000) into a 5L vacuum kneader and stir at 80℃ for 20 minutes. Then, add 250g of fumed silica (specific gravity 200m) sequentially. 2 / g, added in two batches. The first batch consists of 150g added along with the additives. After 20 minutes of agglomeration, another 100g is added. 60g of hydroxyl fluorosilicone oil, 26g of silazane, 15g of cerium oxide, and 2g of zinc stearate are added. Knead at 90℃ and 50Hz for 1 hour.

[0036] (2) Heating, vacuum stage The mixture was heated to 120℃ and kneaded at 35Hz for 1 hour, then heated to 155℃ and kneaded at 35Hz for another hour. The temperature and frequency were then maintained, and the mixture was vacuum degassed for 1 hour at a vacuum level of -0.06 MPa. Finally, the heating was turned off, the frequency was reduced to 15Hz, and vacuum degassed again until the temperature dropped to approximately 95℃. 300g of methyl perfluorinated raw rubber (molecular weight 950,000) was added, and kneading continued for 30 minutes (vacuum level maintained at -0.06 MPa) to obtain the fluorosilicone compound. Purpose: Gradual viscosity reduction, smoothly lowering the system hardness to the target range, and avoiding sudden viscosity changes that could lead to gas entrapment.

[0037] (3) Open mill vulcanization molding: Take 100g of fluorosilicone compound and 1g of bis(2,5) vulcanizing agent and repeatedly mill them evenly on a two-roll open mill (roll gap of open mill 0.5-1.1mm, thin pass 8-12 times, and make triangular bags to fully vent), and vulcanize at 175℃ for 300s in a flat vulcanizing machine (close the mold and vent in sections 2-3 times) to obtain fluorosilicone compound sample.

[0038] Example 4:

[0039] The difference between this embodiment and Embodiment 1 is that, by weight, it includes the following substances: 750g of low-vinyl fluorosilicone raw rubber (vinyl content 0.1%, molecular weight 950,000), 250g of fumed silica, 60g of hydroxyl fluorosilicone oil, 15g of cerium oxide, 26g of silazane, 2g of zinc stearate, and 250g of polymethyltrifluoropropylsiloxane raw rubber.

[0040] Example 5:

[0041] The difference between this embodiment and Embodiment 1 is that, by weight, it includes the following substances: 750g of low-vinyl fluorosilicone raw rubber (vinyl content 0.09%, molecular weight 950,000), 250g of fumed silica, 60g of hydroxyl fluorosilicone oil, 15g of cerium oxide, 26g of silazane, 2g of zinc stearate, and 250g of polymethyltrifluoropropylsiloxane raw rubber.

[0042] Example 6:

[0043] The difference between this embodiment and Embodiment 1 is that, by weight, it includes the following substances: 750g of low-vinyl fluorosilicone raw rubber (vinyl content 0.08%, molecular weight 950,000), 250g of fumed silica, 80g of hydroxyl fluorosilicone oil, 30g of silazane, 15g of cerium oxide and 2g of zinc stearate.

[0044] Example 7:

[0045] The difference between this embodiment and Embodiment 1 is that, by weight, it includes the following substances: 750g of low-vinyl fluorosilicone raw rubber (vinyl content 0.08%, molecular weight 950,000), 250g of fumed silica, 40g of hydroxyl fluorosilicone oil, 20g of silazane, 15g of cerium oxide and 2g of zinc stearate.

[0046] Comparative Example 1 without the addition of methyl perfluorinated raw rubber: (1) Kneading and mixing stage First, weigh 1000g of low-vinyl fluorosilicone raw rubber (vinyl content 0.08%, molecular weight 950,000) into a 5L vacuum kneader and stir at 80℃ for 20 minutes. Then, add 250g of fumed silica (specific gravity 200m) sequentially. 2 / g, added in two batches. The first batch consists of 150g added along with the additives. After 20 minutes of agglomeration, another 100g is added. 60g of hydroxyl fluorosilicone oil, 26g of silazane, 15g of cerium oxide, and 2g of zinc stearate as an internal release agent are added. Knead at 90℃ and 50Hz for 1 hour.

[0047] (2) Heating, vacuum stage Heat to 120℃ and knead at 35Hz for 1 hour, then heat to 155℃ and knead at 35Hz for 1 hour. Then, keep the temperature and frequency constant and degas under vacuum for 1 hour, maintaining a vacuum level of -0.06MPa. Finally, turn off the heating, reduce the frequency to 15Hz, and continue degassing under vacuum for 1 hour to obtain the fluorosilicone compound.

[0048] (3) Open mill vulcanization molding: Take 100g of fluorosilicone compound and 1g of bis(2,5) vulcanizing agent and repeatedly mill them evenly on a two-roll open mill (roll gap of open mill 0.5-1.1mm, thin pass 8-12 times, and make triangular bags to fully vent), and vulcanize at 175℃ for 300s in a flat vulcanizing machine (close the mold and vent in sections 2-3 times) to obtain fluorosilicone compound sample.

[0049] Comparative Example 2: One-step addition of base adhesive (1) Kneading and mixing stage First, weigh 750g of low-vinyl fluorosilicone raw rubber (vinyl content 0.08%, molecular weight 950,000) and 250g of methyl perfluorinated raw rubber (molecular weight 950,000) into a 5L vacuum kneader and stir at 80℃ for 20 minutes. Then, add 250g of fumed silica (specific surface area 200m) sequentially. 2 / g, added in two batches. The first batch is 150g along with 60g hydroxy fluorosilicone oil, 26g silazane, 15g cerium oxide and 2g zinc stearate. After 20min when the mixture forms a ball, add another 100g. Knead at 90℃ and 50Hz for 1h.

[0050] (2) Heating, vacuum stage Heat to 120℃ and knead at 35Hz for 1 hour, then heat to 155℃ and knead at 35Hz for 1 hour. Then, keep the temperature and frequency constant and degas under vacuum for 1 hour, maintaining a vacuum of -0.06MPa. Finally, turn off the heating, reduce the frequency to 15Hz, and continue degassing under vacuum until the temperature drops to about 95℃. Release the vacuum to obtain the fluorosilicone compound.

[0051] (3) Open mill vulcanization molding: Take 100g of fluorosilicone compound and 1g of bis(2,5) vulcanizing agent and repeatedly mill them evenly on a two-roll open mill (roll gap of open mill 0.5-1.1mm, thin pass 8-12 times, and make triangular bags to fully vent), and vulcanize at 175℃ for 300s in a flat vulcanizing machine (close the mold and vent in sections 2-3 times) to obtain fluorosilicone compound sample.

[0052] Test Example 1: The performance of the prepared fluorosilicone compound samples was tested. The test content and methods are as follows: (1) Hardness test: The hardness was tested according to the method described in GB / T 39693.4-2025 Determination of hardness of vulcanized rubber or thermoplastic rubber Part 4: Determination of indentation hardness by Shore hardness tester (Shore hardness).

[0053] (2) Tensile strength and elongation: The tensile length and elongation were tested according to the test methods described in GB / T528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber.

[0054] (3) Tear strength: The tear strength shall be tested in accordance with the test method described in GB / T529-2008 Determination of tear strength of vulcanized rubber or thermoplastic rubber (trouser-shaped, right-angled and crescent-shaped specimens).

[0055] The test results are shown in Table 1.

[0056] ; The data in Table 1 show that the process of compounding low-vinyl fluorosilicone raw rubber with methyl perfluorinated raw rubber, using the two-step method of base rubber and adding methyl perfluorinated raw rubber at a lower temperature, as described in the claims of this invention, can stably prepare ultra-low hardness materials with Shore A hardness of 17–24, tensile strength of 8.8–10.6 MPa, elongation of 598–710%, and tear strength of 19.8–23.8 kN / m, and no air bubbles on the film surface. The overall performance of these materials is superior to that of Comparative Example 1, which does not add methyl perfluorinated raw rubber. Furthermore, compared to Comparative Example 2, which uses a one-step method to add base rubber, this method can stably obtain air bubble-free films, demonstrating significant advantages.

Claims

1. A low-hardness, bubble-free fluorosilicone compound material, characterized in that: By weight, it includes 70-85 parts of vinyl polymethyltrifluoropropylsiloxane raw rubber, 20-27 parts of fumed silica, 5-9 parts of hydroxyl fluorosilicone oil, 1-2 parts of cerium oxide, 2-5 parts of silazane, 0.1-0.3 parts of internal release agent, and 15-30 parts of polymethyltrifluoropropylsiloxane raw rubber; and 1-2% of peroxide vulcanizing agent by weight of the total mass of the above components.

2. The low-hardness, bubble-free fluorosilicone compound material according to claim 1, characterized in that: The vinyl content of the raw vinyl polymethyltrifluoropropylsiloxane is 0.08%-0.1%, and the molecular weight is 800,000-1,500,000; the molecular weight of the raw polymethyltrifluoropropylsiloxane is 800,000-1,500,000.

3. The low-hardness, bubble-free fluorosilicone compound material according to claim 1, characterized in that: The internal release agent is zinc stearate, stearic acid, calcium stearate, or aluminum stearate.

4. The low-hardness, bubble-free fluorosilicone compound material according to claim 1, characterized in that: The peroxide vulcanizing agent is benzoyl peroxide, bis(2,4-dichlorobenzoyl peroxide), 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane, or dicumyl peroxide.

5. A method for preparing a low-hardness, bubble-free fluorosilicone compound material according to any one of claims 1-4, characterized in that: The preparation steps are as follows: S1: Powder kneading stage: Put the vinyl polymethyltrifluoropropylsiloxane raw rubber into a vacuum kneader, heat and stir, then add fumed silica, hydroxyl fluorosilicone oil, silazane, cerium oxide and internal release agent in sequence, and knead by heating. S2: Heating and Vacuum Stage: After kneading the material from step S1, heat and knead it again, then keep it warm and degas it under vacuum. Then cool down and reduce the frequency, degas it under vacuum again, and add polymethyltrifluoropropylsiloxane raw rubber for a second kneading. S3: Vulcanization molding stage: The material obtained after the second kneading in step S2 and the peroxide vulcanizing agent are kneaded on a two-roll mill, and then placed in a flat vulcanizing machine for vulcanization to obtain a low-hardness, bubble-free fluorosilicone compound material.

6. The method for preparing a low-hardness, bubble-free fluorosilicone compound material according to claim 5, characterized in that: In step S1, fumed silica is added in two parts. The first part is added together with hydroxyl fluorosilicone oil, silazane, cerium oxide and internal release agent. The amount added in the first part is 60-72% of the total mass of fumed silica. The second part is added after kneading until the mixture forms a ball.

7. The method for preparing a low-hardness, bubble-free fluorosilicone compound material according to claim 5, characterized in that: In step S1, the stirring temperature is 50-90℃ and the stirring time is 10-20 min; the temperature is raised to 80-90℃ and kneaded at 35-50 Hz for 1-2 h.

8. The method for preparing a low-hardness, bubble-free fluorosilicone compound material according to claim 5, characterized in that: In step S2, the specific operation of heating and kneading is as follows: the material kneaded in step S1 is heated to 100-130℃ and kneaded at 30-40Hz for 0.5-1.5h, and then heated again to 140-160℃ and kneaded at 30-40Hz for 0.5-1.5h.

9. The method for preparing a low-hardness, bubble-free fluorosilicone compound material according to claim 5, characterized in that: In step S2, the vacuum degree is maintained at -0.05 to -0.08 MPa during the vacuum degassing process, and the degassing time is 1-2 hours. The specific operation of cooling and frequency reduction is as follows: turn off the heating and slowly cool down, while reducing the frequency to 10-25 Hz. During the secondary vacuum degassing process, the vacuum degree is maintained at -0.05 to -0.08 MPa, and the secondary kneading time is 30-60 minutes. During the kneading process, the vacuum degree is maintained at -0.05 to -0.08 MPa.

10. The method for preparing a low-hardness, bubble-free fluorosilicone compound material according to claim 5, characterized in that: In step S3, the roll gap of the two-roll open mill is 0.5-1.1 mm, the thin pass is 8-12 times, and the air is vented by forming a triangular bag; the vulcanization temperature is 170-180℃, and the vulcanization time is 300-600s; the air is vented in sections 2-3 times during the mold closing process of vulcanization.

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