Nano-composite high-temperature-resistant insulating rubber and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, in particular to nano composite high-temperature-resistant insulating rubber, which is prepared from the following components in parts by mass: 50 to 70 parts of matrix, 6 to 10 parts of nano silicon dioxide, 3 to 5 parts of nano boron nitride, 1 to 1.5 parts of modifier, 1 to 2 parts of dicumyl peroxide, 1 to 2 parts of triallyl isocyanurate, 3 parts of anti-aging agent and 6 to 10 parts of polyimide micro powder. The matrix is a blend of methyl vinyl silicone rubber and fluororubber, and the modifier is gamma-aminopropyltriethoxysilane. A methyl vinyl silicone rubber and fluororubber blending system is adopted, the advantages of convenient processing and good flexibility of silicone rubber and the characteristics of high temperature resistance and aging resistance of fluororubber are fully played, performance complementation is formed, the high-temperature stability of the material is improved fundamentally, and the problem that processability and high temperature resistance are difficult to achieve at the same time through a single matrix is solved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a nanocomposite high-temperature resistant insulating rubber and its preparation method. Background Technology

[0002] In the field of polymer materials applications, insulating rubber is a key supporting material for high-end scenarios such as electrical equipment, aerospace, and new energy. The synergistic matching of its high-temperature resistance, insulation performance, and mechanical properties directly affects the operational stability and service life of equipment. Currently, most traditional insulating rubbers on the market use a single rubber matrix as the base material. These matrix materials are prone to thermal aging under high-temperature environments, leading to a decrease in tensile strength and loss of flexibility, making it difficult to meet the long-term use requirements of high-temperature conditions.

[0003] In terms of filler modification, existing technologies often use single nanofillers for reinforcement. However, nanofillers have high surface activity and are prone to agglomeration, forming local defects and insufficient interfacial bonding with the rubber matrix. This not only fails to effectively improve the mechanical properties of the material but may also lead to fluctuations in insulation performance due to uneven dispersion. Meanwhile, traditional insulating rubbers often rely on a single crosslinking agent for crosslinking and curing, resulting in poor stability of the crosslinked structure. Under long-term high temperatures, crosslinking bonds are prone to breakage, further exacerbating material performance degradation. Furthermore, some existing manufacturing processes omit key post-processing steps, leaving residual stress inside the material unresolved and resulting in weak interfacial bonding. In practical applications, this can easily lead to cracking and leakage due to temperature changes or external forces. These factors collectively result in technical bottlenecks in existing insulating rubbers, including insufficient high-temperature resistance, limited insulation strength, and a difficulty in balancing mechanical properties and environmental adaptability. These limitations prevent them from meeting the stringent requirements of high-end equipment for comprehensive material performance, restricting their widespread application under complex conditions such as high temperature and high pressure. Summary of the Invention

[0004] The primary objective of this invention is to provide a nanocomposite high-temperature resistant insulating rubber and its preparation method.

[0005] A further objective of this invention is to provide a nanocomposite high-temperature resistant insulating rubber, comprising, by weight, 50-70 parts of matrix, 6-10 parts of nano silica, 3-5 parts of nano boron nitride, 1-1.5 parts of modifier, 1-2 parts of dicumyl peroxide, 1-2 parts of triallyl isocyanurate, 3 parts of antioxidant, and 6-10 parts of polyimide micropowder. The matrix is ​​a blend of methyl vinyl silicone rubber and fluororubber, and the modifier is γ-aminopropyltriethoxysilane.

[0006] Preferably, the mass ratio of methyl vinyl silicone rubber to fluororubber in the matrix is ​​5:2.

[0007] Preferably, the mass ratio of the nano-silica to the nano-boron nitride is 2:1.

[0008] Preferably, the mass ratio of dicumyl peroxide to triallyl isocyanurate is 2:3.

[0009] A method for preparing the aforementioned nanocomposite high-temperature resistant insulating rubber includes the following steps: (1) Pretreatment of nanocomposite fillers: Nano-silica and nano-boron nitride are mixed, then mixed with a modifier and dried for later use; (2) Plasticizing: Mix methyl vinyl silicone rubber and fluororubber in a certain proportion and heat and plasticize until the mixture is uniform; (3) Mixing: Add the pretreated nanocomposite filler, antioxidant and polyimide powder to the plasticized matrix, mix evenly and then add dicumyl peroxide and triallyl isocyanurate, and continue mixing until the rubber compound is uniform. (4) Vulcanization: The mixed rubber compound is placed in a mold, and vulcanized under pressure and heat to initially form a cross-linked structure; (5) Secondary vulcanization: The vulcanized rubber compound is heated and then cooled to room temperature to obtain the finished product.

[0010] Preferably, the pretreatment temperature in step (1) is 80°C and the treatment time is 2 hours.

[0011] Preferably, the plasticizing temperature in step (2) is 65°C and the plasticizing time is 8 minutes.

[0012] Preferably, in step (3), the mixing temperature after adding nanocomposite filler, antioxidant and polyimide powder is 75°C and the mixing time is 18 minutes; after adding dicumyl peroxide and triallyl isocyanurate, the mixing temperature is 65°C and the mixing time is 6 minutes.

[0013] Preferably, in step (4), the vulcanization pressure is 12 MPa, the vulcanization temperature is 160°C, and the vulcanization time is 15 minutes.

[0014] Preferably, the secondary vulcanization temperature in step (5) is 200°C and the secondary vulcanization time is 6 hours.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention employs a blend system of methyl vinyl silicone rubber and fluororubber, fully leveraging the advantages of silicone rubber's convenient processing and good flexibility, and the high temperature resistance and aging resistance of fluororubber, to form a complementary performance, fundamentally improving the high temperature stability of the material and solving the problem that a single matrix cannot simultaneously achieve both processability and high temperature resistance.

[0016] This invention effectively inhibits the agglomeration of nano-fillers by using a combination of nano-silica and nano-boron nitride, combined with the interfacial regulation effect of the modifier, thereby improving the interfacial bonding force between the filler and the matrix. At the same time, by utilizing the synergistic effect of the two nano-fillers, the mechanical strength and basic insulation properties of the material are significantly enhanced.

[0017] 3. This invention introduces polyimide micropowder and nanocomposite fillers to construct a three-dimensional insulating network, significantly improving the material's volume resistivity and breakdown field strength, and enhancing the stability and reliability of its insulation performance. By employing a composite crosslinking system composed of dicumyl peroxide and triallyl isocyanurate, combined with an optimized secondary vulcanization process, the crosslinking structure of the material is further improved, effectively eliminating internal residual stress and significantly enhancing the material's thermal stability, ensuring that it maintains excellent performance even after long-term use in high-temperature environments.

[0018] 4. The nanocomposite high-temperature resistant insulating rubber prepared by this invention combines high mechanical strength, excellent flexibility, superior insulation performance and outstanding high-temperature stability, which can adapt to complex and harsh application conditions, broaden the application range of insulating rubber, and provide reliable material support for high-end electrical equipment, aerospace and other fields. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0020] (1) Raw material composition by mass: 70 parts of methyl vinyl silicone rubber, 10 parts of nano silica, 1 part of modifier γ-aminopropyltriethoxysilane, 2 parts of dicumyl peroxide, and 3 parts of antioxidant D.

[0021] (2) Preparation steps: Nano silica pretreatment: Nano silica is mixed with the modifier γ-aminopropyltriethoxysilane, stirred at 80°C for 2 hours and then dried for later use. The modification improves the interfacial bonding force between the filler and the matrix.

[0022] Plasticizing: The methyl vinyl silicone rubber is put into a mixer and plasticized at 60°C for 5 minutes until it is uniformly melted, laying the foundation for subsequent component mixing.

[0023] Mixing: First, add the pretreated nano silica and antioxidant D, and mix at 70°C for 15 minutes to ensure uniform dispersion. Then, add dicumyl peroxide and mix at 65°C for 5 minutes to obtain a uniform rubber compound.

[0024] Vulcanization: The rubber compound is placed in a mold and vulcanized for 15 minutes at a pressure of 12MPa and a temperature of 160℃ to initially form a cross-linked structure.

[0025] Secondary vulcanization: Heat treatment at 190℃ for 4 hours, then cooling to room temperature to obtain the finished product. Secondary vulcanization is used to initially eliminate internal residual stress. Example

[0026] (1) Raw material composition by mass: 70 parts of methyl vinyl silicone rubber, 8 parts of nano silica, 4 parts of nano boron nitride, 1.2 parts of modifier γ-aminopropyltriethoxysilane, 2 parts of dicumyl peroxide, and 3 parts of antioxidant D.

[0027] (2) Preparation steps: Using the same process parameters as in Example 1, the nanofiller was adjusted to be a composite system of nano-silica and nano-boron nitride. In the pretreatment stage, the two nanofillers were mixed and reacted fully with the modifier γ-aminopropyltriethoxysilane. The mechanical reinforcing properties of nano-silica and the layered insulating and thermally conductive properties of nano-boron nitride formed a synergistic effect, thereby improving the overall performance of the material. Example

[0028] (1) Raw material composition by mass: 50 parts of methyl vinyl silicone rubber, 20 parts of fluororubber, 8 parts of nano silica, 4 parts of nano boron nitride, 1.2 parts of modifier γ-aminopropyltriethoxysilane, 2 parts of dicumyl peroxide, and 3 parts of antioxidant D.

[0029] (2) Preparation steps: The plasticizing step was adjusted to mix methyl vinyl silicone rubber and fluororubber in a certain proportion and plasticize at 65°C for 8 minutes until the mixture was uniform. This utilizes the processing advantages of silicone rubber and the high-temperature resistance of fluororubber to form complementary properties. The remaining steps, including mixing temperature, vulcanization parameters, and secondary vulcanization conditions, were kept consistent with those in Example 2. Example

[0030] (1) The raw material composition by mass is as follows: 50 parts of methyl vinyl silicone rubber, 20 parts of fluororubber, 8 parts of nano silica, 4 parts of nano boron nitride, 1.2 parts of modifier γ-aminopropyltriethoxysilane, 2 parts of dicumyl peroxide, 3 parts of antioxidant D, and 8 parts of polyimide micro powder.

[0031] (2) Preparation steps: After adding the antioxidant during the mixing stage, polyimide micro powder is added simultaneously. The mixing temperature is adjusted to 75°C, and the mixing time is extended to 18 minutes to ensure that the polyimide micro powder and nanocomposite filler are fully dispersed to form a three-dimensional insulating network. The remaining process parameters are consistent with those in Example 3. Example

[0032] (1) Raw material composition by mass: 50 parts methyl vinyl silicone rubber, 20 parts fluororubber, 8 parts nano silica, 4 parts nano boron nitride, 1.2 parts modifier γ-aminopropyltriethoxysilane, 1 part dicumyl peroxide, 1.5 parts triallyl isocyanurate, 3 parts antioxidant D, and 8 parts polyimide micro powder.

[0033] (2) Preparation steps: The crosslinking agent was adjusted to a compound system of dicumyl peroxide and triallyl isocyanurate. The compound crosslinking agent was added at the end of the mixing stage, and the mixture was mixed at 65°C for 6 minutes to ensure uniform dispersion. At the same time, the secondary vulcanization process was optimized by increasing the secondary vulcanization temperature to 200°C and extending the time to 6 hours. The remaining steps were the same as in Example 4.

[0034] Comparative Example 1: (1) The raw material composition is completely identical to that of Example 1 except for nano-silica and nano-boron nitride.

[0035] Comparative Example 2: (1) 70 parts of natural rubber were used to replace the methyl vinyl silicone rubber in Example 1, and the proportions of the remaining raw materials and the preparation steps were completely consistent with those in Example 1.

[0036] Comparative Example 3: (1) Two parts of sulfur were used to replace dicumyl peroxide in Example 1. The proportions of other raw materials and preparation steps were completely consistent with those in Example 1.

[0037] Comparative Example 4: (1) The polyimide micro powder was removed from the raw material composition, and the proportions and preparation steps of the remaining raw materials were completely consistent with those in Example 4.

[0038] Comparative Example 5: (1) The raw material composition is completely consistent with that of Example 5, and the secondary vulcanization process is omitted in the preparation steps.

[0039] Performance testing and results analysis: Test items and standards: (1) The high temperature resistance test refers to GB / T3512-2014. The material is subjected to 72 hours of heat aging treatment at 200℃, 250℃ and 300℃ respectively. The high temperature stability of the material is evaluated by the retention rate of tensile strength and elongation at break. (2) The insulation performance test shall be conducted in accordance with GB / T1408.1-2016 to determine the volume resistivity and GB / T1408.2-2016 to determine the breakdown field strength, which directly reflects the insulation capacity and withstand voltage limit of the material; the mechanical performance test shall be conducted in accordance with GB / T528-2019 to test the tensile strength and elongation at break and GB / T531.1-2008 to test the Shore A hardness, to ensure the structural load-bearing capacity of the material in actual application.

[0040] The test results are shown in Table 1 below:

[0041] The following results can be obtained from Table 1 above: (1) The performance of each example from Example 1 to Example 5 showed a gradual optimization trend, with Example 5 exhibiting the best overall performance: the tensile strength reached 13.2 MPa, an increase of 60.9% compared to Example 1 and 175% compared to Comparative Example 2, demonstrating the synergistic reinforcing effect of the silicon-fluorine blend matrix, nanocomposite filler, and composite crosslinking system; the elongation at break reached 450%, maintaining good flexibility of the material and meeting the deformation requirements of practical applications such as sealing and support; the volume resistivity reached 1.2 × 10⁻⁶. 14 The Ω·m and breakdown field strength reached 28kV / mm, which were 51.3 times and 93.3% higher than those of Comparative Example 1, and 84.6% and 33.3% higher than those of Comparative Example 4, respectively. This confirms that the insulating network constructed by the combination of nano-oxide and nitride and the introduction of polyimide micropowder can significantly enhance the insulation performance. The tensile strength retention rate after 72 hours of heat aging at 300℃ reached 85%, which was 77.1% higher than that of Comparative Example 3 and 30.8% higher than that of Comparative Example 5. This fully demonstrates the key role of the composite crosslinking system and the secondary vulcanization process in improving the thermal stability of the material.

[0042] (2) The properties of Comparative Example 1 without nanocomposite fillers were significantly lower, proving that the combination of nanofillers is the basis for improving mechanical and insulation properties; Comparative Example 2, which uses a single general-purpose rubber matrix, had the worst high-temperature resistance and insulation properties, highlighting the rationality of the selection of silicone rubber, fluororubber and blend system in this invention; Comparative Example 3, which uses a common single crosslinking agent, had insufficient heat aging retention rate and mechanical properties, reflecting the optimization effect of the composite crosslinking system; Comparative Example 4, which lacked insulation modifier, had significantly reduced insulation performance, verifying the synergistic strengthening effect of insulation modifier and nanofiller; Comparative Example 5, which omitted the secondary vulcanization process, had a lower overall performance than Example 5, indicating the importance of process control throughout the process for eliminating internal stress and strengthening interfacial bonding.

[0043] (3) The above test results and analysis fully confirm that the integrated design of matrix blending modification, nanofiller compounding, insulation modifier introduction, composite crosslinking system optimization and process synergistic control of the present invention can achieve simultaneous breakthroughs in high temperature resistance, insulation and mechanical properties.

[0044] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A nanocomposite high-temperature resistant insulating rubber, characterized in that, By weight, it comprises 50-70 parts of matrix, 6-10 parts of nano-silica, 3-5 parts of nano-boron nitride, 1-1.5 parts of modifier, 1-2 parts of dicumyl peroxide, 1-2 parts of triallyl isocyanurate, 3 parts of antioxidant and 6-10 parts of polyimide micro powder. The matrix is ​​a blend of methyl vinyl silicone rubber and fluororubber, and the modifier is γ-aminopropyltriethoxysilane.

2. The nanocomposite high-temperature resistant insulating rubber according to claim 1, characterized in that, The mass ratio of methyl vinyl silicone rubber to fluororubber in the matrix is ​​5:

2.

3. The nanocomposite high-temperature resistant insulating rubber according to claim 1, characterized in that, The mass ratio of nano-silica to nano-boron nitride is 2:

1.

4. The nanocomposite high-temperature resistant insulating rubber according to claim 1, characterized in that, The mass ratio of dicumyl peroxide to triallyl isocyanurate is 2:

3.

5. A method for preparing a nanocomposite high-temperature resistant insulating rubber as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Pretreatment of nanocomposite fillers: Nano-silica and nano-boron nitride are mixed, then mixed with a modifier and dried for later use; (2) Plasticizing: Mix methyl vinyl silicone rubber and fluororubber in a certain proportion and heat and plasticize until the mixture is uniform; (3) Mixing: Add the pretreated nanocomposite filler, antioxidant and polyimide powder to the plasticized matrix, mix evenly and then add dicumyl peroxide and triallyl isocyanurate, and continue mixing until the rubber compound is uniform. (4) Vulcanization: The mixed rubber compound is placed in a mold, and vulcanized under pressure and heat to initially form a cross-linked structure; (5) Secondary vulcanization: The vulcanized rubber compound is heated and then cooled to room temperature to obtain the finished product.

6. The preparation method according to claim 5, characterized in that, The pretreatment temperature in step (1) is 80℃ and the treatment time is 2 hours.

7. The preparation method according to claim 5, characterized in that, In step (2), the plasticizing temperature is 65℃ and the plasticizing time is 8 minutes.

8. The preparation method according to claim 5, characterized in that, In step (3), the mixing temperature after adding nanocomposite filler, antioxidant and polyimide powder is 75°C and the mixing time is 18 minutes; after adding dicumyl peroxide and triallyl isocyanurate, the mixing temperature is 65°C and the mixing time is 6 minutes.

9. The preparation method according to claim 5, characterized in that, In step (4), the vulcanization pressure is 12 MPa, the vulcanization temperature is 160℃, and the vulcanization time is 15 minutes.

10. The preparation method according to claim 5, characterized in that, In step (5), the secondary vulcanization temperature is 200℃ and the secondary vulcanization time is 6 hours.

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