A high flame-retardant insulating phenyl silicone rubber for power applications and its preparation method

Abstract

This invention discloses a high flame-retardant insulating phenyl silicone rubber for power applications and its preparation method, belonging to the field of silicone rubber technology. The phenyl silicone rubber, by weight, comprises the following raw material components: matrix material: 80-100 parts of vinyl-terminated polydimethylsiloxane and 20-30 parts of phenyl silicone rubber; reinforcing agent: 30-50 parts of fumed silica; flame retardant: 25-40 parts of modified magnesium hydroxide, 10-15 parts of ammonium polyphosphate, and 5-10 parts of melamine cyanurate; thermally conductive filler: 15-25 parts of nano-boron nitride; structure modifier: 2-4 parts of diphenylsilanediol and 3-6 parts of phenyl silicone oil; crosslinking agent: 8-12 parts of hydrogen-containing silicone oil; catalyst: 0.2-0.4 parts of platinum catalyst; inhibitor: 0.1-0.3 parts of ethynylcyclohexanol; functional additives: 1-3 parts of silane coupling agent and 0.5-1 parts of antioxidant.

Description

Technical Field

[0001] This invention relates to the field of silicone rubber technology, and in particular to a high flame-retardant insulating phenyl silicone rubber for power applications and its preparation method. Background Technology

[0002] With the rapid development of the power industry, the performance requirements for silicone rubber materials are increasing. Especially in critical power facilities such as transmission lines and substation equipment, silicone rubber not only needs excellent insulation properties but also good flame retardant characteristics to cope with potential short circuits, overloads, and other emergencies. Traditional silicone rubber materials often face the challenge of achieving a balance between flame retardancy, mechanical properties, and insulation performance.

[0003] In existing technologies, such as the patent with publication number CN119931347A, a high-performance silicone rubber is disclosed. This rubber uses nano-boron nitride and fumed silica as thermally conductive fillers, and nano-magnesium hydroxide, ammonium polyphosphate, and melamine cyanurate as flame retardants, achieving a comprehensive improvement in the silicone rubber's insulation, flame retardancy, thermal conductivity, and mechanical properties. However, its structural stability under extreme high-temperature conditions and its long-term reliability still have room for improvement.

[0004] In addition, patent CN120173416A proposes a ceramicizable silicone rubber insulating material, which improves fire resistance by forming a ceramic layer at high temperature through ceramic filler. However, the preparation process of this material is relatively complex, and its mechanical properties at room temperature are somewhat sacrificed.

[0005] Therefore, developing a silicone rubber material for power applications that combines high flame retardancy, excellent insulation properties, and good mechanical properties, and whose preparation process is relatively simple, has significant practical importance and application value. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a high flame-retardant insulating phenyl silicone rubber for power applications and its preparation method, so as to solve the problems mentioned in the background art.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: This invention discloses a high flame-retardant insulating phenyl silicone rubber for power applications, comprising the following raw material components by weight: Matrix material: including 80-100 parts of vinyl-terminated polydimethylsiloxane and 20-30 parts of phenyl silicone rubber; Reinforcing agent: 30-50 parts of fumed silica; Flame retardants include 25-40 parts modified magnesium hydroxide, 10-15 parts ammonium polyphosphate, and 5-10 parts melamine cyanurate. Thermally conductive filler: 15-25 parts of nano boron nitride; Structure modifiers: including 2-4 parts diphenylsilanediol and 3-6 parts phenyl silicone oil; Crosslinking agent: 8-12 parts of hydrogen-containing silicone oil; Catalyst: 0.2–0.4 parts platinum catalyst; Inhibitor: Ethynylcyclohexanol 0.1–0.3 parts; Functional additives: including 1-3 parts of silane coupling agent and 0.5-1 part of antioxidant.

[0008] Preferably, the viscosity of the vinyl-terminated polydimethylsiloxane is 5000-10000 cst.

[0009] Preferably, the phenyl silicone rubber has a phenyl content of 15-25% and a vinyl content of 0.2-0.5%.

[0010] Preferably, the specific surface area of ​​the fumed silica is 200–300 m². 2 / g, with a particle size of 7–16 nm.

[0011] Preferably, the method for preparing the modified magnesium hydroxide includes: Magnesium hydroxide was dried at 100–120°C for 3–5 hours, then treated with an ethanol solution containing 2–5% silane coupling agent, stirred at high speed, and dried at 100–120°C for 4 hours. The average particle size of the magnesium hydroxide was 40–65 nm.

[0012] Preferably, the average lateral dimension of the boron nitride nanoparticles is 60–80 nm, and the thickness is 20–50 nm.

[0013] Another aspect of the present invention discloses a method for preparing the aforementioned high flame-retardant insulating phenyl silicone rubber for power applications, the preparation method comprising the following steps: Step S1: Packing material pretreatment Magnesium hydroxide was modified to obtain modified magnesium hydroxide. Step S2: Preparation of base adhesive Add vinyl-terminated polydimethylsiloxane and phenyl silicone rubber to a kneader and stir at 40-60°C for 10-15 minutes. Then add 1 / 3 of fumed silica, diphenylsilanediol and 1 / 2 of phenyl silicone oil and continue stirring for 20-30 minutes. Step S3: Adding filler Modified magnesium hydroxide, ammonium polyphosphate, melamine cyanurate, nano boron nitride, the remaining fumed silica and phenyl silicone oil are added in sequence, and stirred at 50-70°C for 40-60 minutes. Step S4: Addition of additives Add silane coupling agent and antioxidant, stir for 15-20 minutes, then cool to below 40°C, add hydrogen-containing silicone oil, platinum catalyst and inhibitor, and stir for 10-15 minutes; Step S5: Vacuum degassing The mixture is placed in a vacuum degassing vessel and degassed for 30 to 45 minutes under a vacuum of -0.09 to -0.098 MPa. Step S6: Vulcanization molding The degassed material is injected into a mold and vulcanized at 120–150°C and 10–15 MPa for 30–60 minutes. Then, it is vulcanized again at 200°C for 4–6 hours to obtain high flame-retardant insulating phenyl silicone rubber.

[0014] The above technical solution has the following beneficial effects: The invention utilizes a vinyl-terminated polydimethylsiloxane compounded with phenyl silicone rubber as the matrix material, combined with the reinforcing effect of fumed silica, to give the silicone rubber excellent mechanical properties. Simultaneously, the introduction of phenyl groups improves the material's high-temperature resistance and flame retardancy.

[0015] Modified magnesium hydroxide, ammonium polyphosphate, and melamine cyanurate were used as flame retardants. The synergistic effect of these three flame retardants greatly improved the flame retardant properties of silicone rubber. Among them, modified magnesium hydroxide not only played a flame retardant role but also improved compatibility with the matrix and enhanced the mechanical properties of the material.

[0016] Adding nano-boron nitride as a thermally conductive filler can form a thermally conductive path in the silicone rubber matrix, improve the thermal conductivity of the material, and help dissipate heat in a timely manner during use, thus avoiding excessive local temperature.

[0017] By optimizing the formulation and preparation process, the silicone rubber of the present invention has excellent insulation properties, with a volume resistivity of over 1.0×10¹⁵ Ω·cm and a dielectric strength greater than 30 kV / mm.

[0018] The silicone rubber of this invention has excellent comprehensive performance, with a flame retardant rating of UL-V0, a ​​tensile strength greater than 5 MPa, and an elongation at break of over 200%, which can meet the stringent material requirements of power equipment. Detailed Implementation

[0019] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Example 1

[0020] A high flame-retardant insulating silicone rubber for power applications, with the following raw material composition by weight: 90 parts of vinyl-terminated polydimethylsiloxane, with a viscosity of 8000 cSt and a vinyl content of 0.25%; 25 parts of phenyl silicone rubber, with a phenyl content of 20% and a vinyl content of 0.35%; 40 parts of fumed silica have a specific surface area of ​​250 m². 2 / g, with a particle size of 10nm; 30 parts of modified magnesium hydroxide have an average particle size of 50 nm; 12 parts of ammonium polyphosphate; 8 parts of melamine cyanurate; Twenty parts of nano-boron nitride, with a transverse dimension of 70 nm and a thickness of 35 nm; 3 parts of diphenylsilanediol; 5 parts phenyl silicone oil; 10 parts of hydrogen-containing silicone oil, of which the Si-H content is 1.2%; 0.3 parts platinum catalyst; 0.2 parts of ethynylcyclohexanol; 2 parts of γ-aminopropyltriethoxysilane; 0.8 parts of triphenyl phosphite.

[0021] The preparation method is as follows: Preparation of modified magnesium hydroxide: magnesium hydroxide was dried at 110℃ for 4 hours, then treated with an ethanol solution containing 3% γ-aminopropyltriethoxysilane, stirred at high speed, and then dried at 110℃ for 4 hours. Preparation of base compound: Add vinyl-terminated polydimethylsiloxane and phenyl silicone rubber to a kneader and stir at 50°C for 12 minutes. Then add 1 / 3 of fumed silica, diphenylsilanediol and 1 / 2 of phenyl silicone oil and continue stirring for 25 minutes. Filler addition: Modified magnesium hydroxide, ammonium polyphosphate, melamine cyanurate, nano boron nitride, the remaining fumed silica and phenyl silicone oil are added in sequence, and stirred at 60°C for 50 minutes; Additives: Add γ-aminopropyltriethoxysilane and triphenyl phosphite, stir for 18 minutes, then cool to below 40°C, add hydrogen-containing silicone oil, platinum catalyst and ethynylcyclohexanol, and stir for 12 minutes; Vacuum degassing: Place the mixture into a vacuum degassing vessel and degas for 40 minutes under a vacuum of -0.095 MPa; Vulcanization molding: The degassed material is injected into the mold and vulcanized at 135℃ and 12 MPa for 45 minutes, and then vulcanized again at 200℃ for 5 hours to obtain high flame retardant insulating phenyl silicone rubber. Example 2

[0022] A high flame-retardant insulating silicone rubber for power applications, with the following raw material composition by weight: 80 parts of vinyl-terminated polydimethylsiloxane, with a viscosity of 5000 cSt and a vinyl content of 0.15%; 20 parts of phenyl silicone rubber, with a phenyl content of 15% and a vinyl content of 0.2%; 30 parts of fumed silica, with a specific surface area of ​​200 m². 2 / g, with a particle size of 7nm; 25 parts of modified magnesium hydroxide have an average particle size of 40 nm; 10 parts of ammonium polyphosphate; 5 parts of melamine cyanurate; Fifteen portions of nano-boron nitride, each with a transverse dimension of 60 nm and a thickness of 20 nm; 2 parts diphenylsilanediol 3 parts phenyl silicone oil Eight parts of hydrogen-containing silicone oil, of which the Si-H content is 0.8%; 0.2 parts platinum catalyst; 0.1 parts of ethynylcyclohexanol; 1 part of γ-glycidyl etheroxypropyltrimethoxysilane; 0.5 parts of triphenyl phosphite.

[0023] The preparation method is as follows: Preparation of modified magnesium hydroxide: magnesium hydroxide was dried at 100℃ for 5 hours, then treated with an ethanol solution containing 2% γ-glycidoxypropyltrimethoxysilane, stirred at high speed, and dried at 100℃ for 4 hours. Preparation of base compound: Add vinyl-terminated polydimethylsiloxane and phenyl silicone rubber to a kneader and stir at 40°C for 15 minutes. Then add 1 / 3 of fumed silica, diphenylsilanediol and 1 / 2 of phenyl silicone oil and continue stirring for 30 minutes. Filler addition: Modified magnesium hydroxide, ammonium polyphosphate, melamine cyanurate, nano boron nitride, the remaining fumed silica and phenyl silicone oil are added in sequence, and stirred at 50°C for 60 minutes; Additives: Add γ-glycidoxypropyltrimethoxysilane and triphenyl phosphite, stir for 20 minutes, then cool to below 40°C, add hydrogen-containing silicone oil, platinum catalyst and ethynylcyclohexanol, and stir for 15 minutes; Vacuum degassing: Place the mixture into a vacuum degassing vessel and degas for 45 minutes under a vacuum of -0.09 MPa; Vulcanization molding: The degassed material is injected into the mold and vulcanized at 120℃ and 10 MPa for 60 minutes, and then vulcanized again at 200℃ for 6 hours to obtain high flame retardant insulating silicone rubber. Example 3

[0024] A high flame-retardant insulating silicone rubber for power applications, with the following raw material composition by weight: 100 parts of vinyl-terminated polydimethylsiloxane, with a viscosity of 10,000 cSt and a vinyl content of 0.35%; 30 parts of phenyl silicone rubber, with a phenyl content of 25% and a vinyl content of 0.5%; 50 parts of fumed silica with a specific surface area of ​​300 m² 2 / g, with a particle size of 16 nm; 40 parts of modified magnesium hydroxide have an average particle size of 65 nm; 15 parts of ammonium polyphosphate; 10 parts of melamine cyanurate; 25 parts of boron nitride nanoparticles, with a transverse dimension of 80 nm and a thickness of 50 nm; 4 parts of diphenylsilanediol; 6 parts of phenyl silicone oil; 12 parts of hydrogen-containing silicone oil, of which the Si-H content is 1.6%; 0.4 parts platinum catalyst; 0.3 parts of ethynylcyclohexanol; 3 parts of γ-aminopropyltriethoxysilane; 1 part of triphenyl phosphite.

[0025] Preparation method: Preparation of modified magnesium hydroxide: magnesium hydroxide was dried at 120°C for 3 hours, then treated with an ethanol solution containing 5% γ-aminopropyltriethoxysilane, stirred at high speed, and then dried at 120°C for 4 hours. Preparation of base compound: Add vinyl-terminated polydimethylsiloxane and phenyl silicone rubber to a kneader and stir at 60°C for 10 minutes. Then add 1 / 3 of fumed silica, diphenylsilanediol and 1 / 2 of phenyl silicone oil and continue stirring for 20 minutes. Filler addition: Modified magnesium hydroxide, ammonium polyphosphate, melamine cyanurate, nano boron nitride, the remaining fumed silica and phenyl silicone oil are added in sequence, and stirred at 70°C for 40 minutes; Additives: Add γ-aminopropyltriethoxysilane and triphenyl phosphite, stir for 15 minutes, then cool to below 40°C, add hydrogen-containing silicone oil, platinum catalyst and ethynylcyclohexanol, and stir for 10 minutes; Vacuum degassing: Place the mixture into a vacuum degassing vessel and degas for 30 minutes under a vacuum of -0.098 MPa; Vulcanization molding: The degassed material is injected into the mold and vulcanized at 150℃ and 15 MPa for 30 minutes, and then vulcanized again at 200℃ for 4 hours to obtain high flame retardant insulating silicone rubber.

[0026] Comparative Example 1 The difference between this comparative example and Example 1 is that phenyl silicone rubber is not added, while the other raw materials and preparation methods are the same as in Example 1.

[0027] Comparative Example 2 The difference between this comparative example and Example 1 is that no nano-boron nitride is added, while the other raw materials and preparation methods are the same as in Example 1.

[0028] Comparative Example 3 The difference between this comparative example and Example 1 is that only modified magnesium hydroxide is used as the flame retardant, and ammonium polyphosphate and melamine cyanurate are not added. Other raw materials and preparation methods are the same as in Example 1.

[0029] The performance of silicone rubber prepared using the raw material components of Examples 1, 2, and 3, as well as Comparative Examples 1, 2, and 3, was tested. The test results are shown in Table 1 below.

[0030] Table 1:

[0031] As can be seen from the above test results, the high flame-retardant insulating silicone rubber for power prepared in Examples 1-3 of the present invention has excellent comprehensive performance, and exhibits good performance in terms of tensile strength, elongation at break, hardness, volume resistivity, dielectric strength, flame retardancy rating, thermal conductivity and aging resistance.

[0032] Compared with Comparative Example 1, Examples 1-3 with added phenyl silicone rubber showed significant improvements in high temperature resistance and flame retardancy, higher tensile strength retention after aging at 200°C, and an improved flame retardancy rating from UL-V1 to UL-V0.

[0033] Compared with Comparative Example 2, Examples 1-3 with added nano boron nitride showed a significant improvement in thermal conductivity, which helps the material dissipate heat during use.

[0034] Compared with Comparative Example 3, Examples 1-3, which use compound flame retardants, show a significant improvement in flame retardant performance, with the flame retardant rating increasing from UL-V1 to UL-V0.

[0035] In summary, through reasonable formulation design and preparation process, this invention has successfully prepared a silicone rubber material for power applications that combines high flame retardancy, excellent insulation performance, and good mechanical properties, and has broad application prospects.

[0036] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A high flame-retardant insulating phenyl silicone rubber for power applications, characterized in that, By weight, it includes the following raw material components: Matrix material: including 80-100 parts of vinyl-terminated polydimethylsiloxane and 20-30 parts of phenyl silicone rubber; Reinforcing agent: 30-50 parts of fumed silica; Flame retardants include 25-40 parts modified magnesium hydroxide, 10-15 parts ammonium polyphosphate, and 5-10 parts melamine cyanurate. Thermally conductive filler: 15-25 parts of nano boron nitride; Structure modifiers: including 2-4 parts diphenylsilanediol and 3-6 parts phenyl silicone oil; Crosslinking agent: 8-12 parts of hydrogen-containing silicone oil; Catalyst: 0.2–0.4 parts platinum catalyst; Inhibitor: Ethynylcyclohexanol 0.1–0.3 parts; Functional additives: including 1-3 parts of silane coupling agent and 0.5-1 part of antioxidant.

2. The high flame-retardant insulating phenyl silicone rubber for power applications and its preparation method according to claim 1, characterized in that, The viscosity of the vinyl-terminated polydimethylsiloxane is 5000-10000 cst.

3. The high flame-retardant insulating phenyl silicone rubber for power applications and its preparation method according to claim 1, characterized in that, The phenyl silicone rubber has a phenyl content of 15-25% and a vinyl content of 0.2-0.5%.

4. The high flame-retardant insulating phenyl silicone rubber for power applications and its preparation method according to claim 1, characterized in that, The specific surface area of ​​the fumed silica is 200–300 m². 2 / g, with a particle size of 7–16 nm.

5. The high flame-retardant insulating phenyl silicone rubber for power applications and its preparation method according to claim 1, characterized in that, The method for preparing the modified magnesium hydroxide includes: Magnesium hydroxide was dried at 100–120°C for 3–5 hours, then treated with an ethanol solution containing 2–5% silane coupling agent, stirred at high speed, and dried at 100–120°C for 4 hours. The average particle size of the magnesium hydroxide was 40–65 nm.

6. The high flame-retardant insulating phenyl silicone rubber for power applications and its preparation method according to claim 1, characterized in that, The average lateral dimension of the boron nitride nanoparticles is 60–80 nm, and the thickness is 20–50 nm.

7. The high flame-retardant insulating phenyl silicone rubber for power applications and its preparation method according to claim 1, characterized in that, The silane coupling agent is selected from one or a mixture of two or more of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

8. A method for preparing a high flame-retardant insulating phenyl silicone rubber for electrical applications as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: Step S1: Packing material pretreatment Magnesium hydroxide was modified to obtain modified magnesium hydroxide. Step S2: Preparation of base adhesive Add vinyl-terminated polydimethylsiloxane and phenyl silicone rubber to a kneader and stir at 40-60°C for 10-15 minutes. Then add 1 / 3 of fumed silica, diphenylsilanediol and 1 / 2 of phenyl silicone oil and continue stirring for 20-30 minutes. Step S3: Adding filler Modified magnesium hydroxide, ammonium polyphosphate, melamine cyanurate, nano boron nitride, the remaining fumed silica and phenyl silicone oil are added in sequence, and stirred at 50-70°C for 40-60 minutes. Step S4: Addition of additives Add silane coupling agent and antioxidant, stir for 15-20 minutes, then cool to below 40°C, add hydrogen-containing silicone oil, platinum catalyst and inhibitor, and stir for 10-15 minutes; Step S5: Vacuum degassing The mixture is placed in a vacuum degassing vessel and degassed for 30 to 45 minutes under a vacuum of -0.09 to -0.098 MPa. Step S6: Vulcanization molding The degassed material is injected into a mold and vulcanized at 120–150°C and 10–15 MPa for 30–60 minutes. Then, it is vulcanized again at 200°C for 4–6 hours to obtain high flame-retardant insulating phenyl silicone rubber.

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