High-temperature-resistant silicone sealant, preparation method and application thereof

Abstract

The application relates to the technical field of high-molecular sealing materials, and discloses a high-temperature-resistant silicone sealant as well as a preparation method and application thereof. The sealant is composed of hydroxyl-terminated polymethylphenylsiloxane, glass powder, fumed silica, phenyl silicone oil, ferrous oxide, a crosslinking agent, a silane coupling agent and a catalyst. In the preparation, the base glue, the glass powder and the ferrous oxide are vacuum-dewatered to prepare a base material, and then the crosslinking agent, the fumed silica and other components are sequentially added and mixed. The sealant is air-dried at room temperature for 6-12 minutes, has excellent extrusion performance, after high-temperature aging at 360 DEG C for 24 hours, the tensile strength retention rate reaches 97.8%, the elongation at break retention rate reaches 92.7%, the adhesive cohesive failure area is more than 95%, long-term high-temperature resistance of 300-360 DEG C is realized, the problems of high-temperature loss of elasticity and adhesive failure of conventional silicone glue are solved, and the process is suitable for industrial-scale application.

Description

Technical Field

[0001] This invention relates to the field of polymer sealing materials technology, and more specifically, to a high-temperature resistant silicone sealant, its preparation method, and its application. Background Technology

[0002] Silicone sealants, thanks to the superior properties imparted by their silicon-oxygen-silicon backbone, are widely used in various fields. However, conventional products, based on hydroxyl-terminated polydimethylsiloxane, have a temperature resistance of only -45 to 200°C, which is insufficient to meet the long-term temperature resistance requirements of industries such as new energy and high-end manufacturing, which require temperatures of 300 to 350°C, becoming a key bottleneck for industrial upgrading. Currently, high-temperature sealing materials are widely used in high-temperature pipelines, industrial furnaces, and other high-temperature operating environments, with increasingly stringent requirements for the high-temperature resistance and sealing reliability of these materials.

[0003] To overcome the temperature resistance limit, existing technologies have undergone targeted improvements. Patent CN109575872A uses hydroxyl-terminated polymethylphenylsiloxane combined with silane-modified graphene to improve temperature resistance. Although it achieves anti-mildew function, the actual temperature resistance does not exceed 300℃. Moreover, graphene is difficult to disperse and easily agglomerates at high temperatures, leading to embrittlement of the adhesive layer and a significant decrease in elongation at break, failing to guarantee the required sealing elasticity. At the same time, high-end fillers drive up production costs, making large-scale application difficult. Patent CN111019592A uses modified nano-silica combined with borate-type flame retardants, focusing on maintaining the integrity of components in fireproof sealing scenarios. The base material is still mainly polydimethylsiloxane, which inherently has limited temperature resistance. Above 300℃, the adhesive layer is prone to hardening and cracking, the cohesive failure area decreases, and the adhesion durability is insufficient, failing to meet the core requirements of high-temperature sealing.

[0004] In addition, existing technologies either cause compatibility issues leading to poor operability at room temperature due to base material modification and plasticizer compatibility with the system, or have limited effect on improving temperature resistance, and still cannot achieve long-term stable use above 300℃. Summary of the Invention

[0005] To overcome the shortcomings of the existing high-temperature silicone sealant, such as insufficient maximum temperature resistance, loss of elasticity at high temperatures, adhesion failure, and high cost, this invention provides a high-temperature silicone sealant. Another object of the present invention is to provide a method for preparing a high-temperature resistant silicone sealant; Another object of the present invention is to provide an application of a high-temperature resistant silicone sealant.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A high-temperature resistant silicone sealant comprises the following raw materials in parts by weight: 100 parts of hydroxyl-terminated polymethylphenylsiloxane, 20-40 parts of glass powder, 3-6 parts of fumed silica, 5-15 parts of phenyl silicone oil, 5-10 parts of ferric oxide, 6-10 parts of crosslinking agent, 1-3 parts of silane coupling agent, and 0.05-0.15 parts of catalyst.

[0007] Furthermore, the phenyl molar fraction of the hydroxyl-terminated polymethylphenylsiloxane is 8% to 12%; and the phenyl molar fraction of the phenyl silicone oil is 20% to 30%.

[0008] Preferably, the phenyl molar fraction of the hydroxyl-terminated polymethylphenylsiloxane is 10%.

[0009] Preferably, the viscosity of hydroxyl-terminated polymethylphenylsiloxane at 25°C is 20,000–50,000 mPa·s.

[0010] Preferably, the viscosity of the phenyl silicone oil is 100–350 mPa·s.

[0011] Furthermore, the ratio of the phenyl molar fraction of the phenyl silicone oil to the phenyl molar fraction of the hydroxyl-terminated polymethylphenylsiloxane is 2 to 3:1.

[0012] Furthermore, the weight ratio of glass powder to ferric oxide is 2:1 to 8:1.

[0013] Furthermore, the median particle size D50 of the glass powder is 4–8 μm; the median particle size D50 of the ferric oxide is 3–5 μm.

[0014] Furthermore, the initial melting point of the glass powder is 300–340°C.

[0015] Furthermore, the fumed silica has a particle size of 30 nm to 40 nm and a specific surface area of ​​300 to 400 m². 2 / g.

[0016] Preferably, the crosslinking agent is one or a combination of methyltributanone oxime silane, vinyltributanone oxime silane, and phenyltributanone oxime silane; The silane coupling agent is one or a combination of γ-aminoethylaminopropyltrimethoxysilane, γ-aminoethylaminopropyltriethoxysilane, and hexamethyldisilazane. The catalyst is di-n-butyltin dilaurate and / or di-n-butyltin diacetate.

[0017] A method for preparing the high-temperature resistant silicone sealant includes the following steps: heating and dehydrating hydroxyl-terminated polymethylphenylsiloxane, glass powder, and ferric oxide under vacuum conditions to obtain a base material with a water content of less than 0.05% and cooling it; adding a crosslinking agent to the cooled base material under vacuum conditions and mixing it evenly; then adding fumed silica; and then adding phenyl silicone oil, silane coupling agent, and catalyst and stirring and mixing evenly to obtain the high-temperature resistant silicone sealant.

[0018] Preferably, hydroxyl-terminated polymethylphenylsiloxane, glass powder, and ferric oxide are stirred, kneaded, and dehydrated for 1-3 h under a vacuum of -0.09 to -0.1 MPa and a temperature of 120±2℃.

[0019] Preferably, the crosslinking agent is added to the cooled base material under the conditions of vacuum degree -0.08 to -0.1 MPa, stirring frequency 20 to 25 Hz, and dispersion frequency 30 to 35 Hz.

[0020] An application of the aforementioned high-temperature resistant silicone sealant in sealing and bonding at temperatures of 300–360°C. Further, the application is for sealing applications including new energy equipment, high-temperature pipelines, industrial furnaces, sensors, and high-temperature cooking appliances.

[0021] This invention achieves a long-term temperature resistance of 300℃ to 360℃ through the synergistic effect of its components, forming a high-temperature stable adhesive layer structure. Hydroxyl-terminated polymethylphenylsiloxane serves as the base material, constructing a colloidal molecular foundation with excellent temperature resistance. Low-melting-point glass powder melts and solidifies under high-temperature conditions to form a continuous film wall structure, creating a stable internal support framework. Ferric oxide works synergistically with the glass powder, providing both temperature resistance assistance and controlling the morphology of the melt-formed glass powder, thus enhancing the structural stability of the temperature-resistant framework. Phenyl silicone oil, while synergistically supporting the base material in terms of temperature resistance, precisely adjusts the sealant's consistency, balancing high-temperature resistance with room-temperature operability. A silane coupling agent achieves interfacial bonding between the organic base material and the inorganic filler, ensuring both the basic adhesive performance of the sealant and improving adhesive stability under high-temperature conditions, ensuring a reliable sealing structure. The mutual support of the components achieves a synergistic effect of heat resistance in the base material molecules, support from the inorganic framework, and stable interfacial bonding.

[0022] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: The sealant of this invention exhibits good processability and basic performance at room temperature, with a surface drying time of 6-12 min and an extrusion rate of 22.5-33.8 g / min, meeting the operational requirements of industrial construction. It possesses excellent elasticity and mechanical properties, with a Shore hardness of 40-46, tensile strength of 0.92-1.12 MPa, and elongation at break of 303-352%. Furthermore, it exhibits excellent electrical properties such as volume resistivity and breakdown voltage, making it suitable for sealing needs in various scenarios. After aging at 360℃ for 24 hours, the retention rate of all properties is above 80%, with tensile strength retention of 88.3%-97.8%, elongation at break retention of 84.2%-92.7%, and the cohesive failure area of ​​the adhesive still exceeding 95%. There is no significant deterioration in hardness, indicating that the high-temperature resistant silicone sealant of this invention can maintain structural integrity, elasticity, and adhesive reliability under long-term high-temperature conditions of 300-360℃, fully meeting the core requirements of high-temperature sealing. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0024] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0025] The glass powder used in the examples had a median particle size D50 of 4–8 μm, ferric oxide had a median particle size D50 of 3–5 μm, and fumed silica had a particle size of 30 nm–40 nm, with a specific surface area of ​​300–400 m². 2 / g.

[0026] Example 1 Preparation of a high-temperature resistant silicone sealant: 1. The raw materials are composed of the following parts by weight: 100 parts of hydroxyl-terminated polymethylphenylsiloxane, 40 parts of low-melting-point glass powder, 6 parts of fumed silica, 15 parts of phenyl silicone oil, 5 parts of ferric oxide, 10 parts of crosslinking agent, 2 parts of silane coupling agent, and 0.05 parts of di-n-butyltin dilaurate. The hydroxyl-terminated polymethylphenylsiloxane has a viscosity of 20,000 mPa·s at 25°C and a phenyl molar fraction of 10%; the phenyl silicone oil has a viscosity of 350 mPa·s and a phenyl molar fraction of 25%. The crosslinking agent is 8 parts by weight of methyl tributanone oxime silane and 2 parts by weight of phenyl tributanone oxime silane.

[0027] The silane coupling agent is 1 part by weight of γ-aminoethylaminopropyltrimethoxysilane and 1 part by weight of hexamethyldisilazane.

[0028] 2. The preparation method is as follows: The hydroxyl-terminated polymethylphenylsiloxane, low-melting-point glass powder, and ferric oxide were stirred, kneaded, and dehydrated for 2 hours under a vacuum of -0.09 MPa and a temperature of 120±2℃ to prepare a base material with a water content of less than 0.05%, which was then cooled. The cooled base material and crosslinking agent were stirred and mixed for 20 minutes under a vacuum of -0.09 MPa, a stirring frequency of 20 Hz, and a dispersion frequency of 30 Hz. Fumed silica was added and stirred and mixed for 15 minutes under a stirring frequency of 20 Hz and a dispersion frequency of 30 Hz. Phenyl silicone oil, silane coupling agent, and catalyst were added and stirred and mixed for 20 minutes under a vacuum of -0.1 MPa, a stirring frequency of 20 Hz, and a dispersion frequency of 30 Hz. The mixture was then discharged and filled to obtain a high-temperature resistant silicone sealant product.

[0029] Example 2 Preparation of a high-temperature resistant silicone sealant: 1. The raw materials are composed of the following parts by weight: 100 parts of hydroxyl-terminated polymethylphenylsiloxane, 20 parts of low-melting-point glass powder, 4 parts of fumed silica, 10 parts of phenyl silicone oil, 10 parts of ferric oxide, 10 parts of crosslinking agent, 2 parts of silane coupling agent, and 0.1 parts of di-n-butyltin diacetate; The hydroxyl-terminated polymethylphenylsiloxane has a viscosity of 50,000 mPa·s at 25°C and a phenyl molar fraction of 10%; the phenyl silicone oil has a viscosity of 100 mPa·s and a phenyl molar fraction of 20%. The crosslinking agent is composed of 8 parts by weight of methyl tributanone oxime silane, 1 part of vinyl tributanone oxime silane, and 1 part of phenyl tributanone oxime silane.

[0030] The silane coupling agent is composed of 1.2 parts by weight of γ-aminoethylaminopropyltrimethoxysilane and 0.8 parts by weight of hexamethyldisilazane.

[0031] 2. The preparation method is as follows: The hydroxyl-terminated polymethylphenylsiloxane, low-melting-point glass powder, and ferric oxide were stirred, kneaded, and dehydrated for 2 hours under a vacuum of -0.09 MPa and a temperature of 120±2℃ to prepare a base material with a water content of less than 0.05%, which was then cooled. The cooled base material and crosslinking agent were stirred and mixed for 20 minutes under a vacuum of -0.1 MPa, a stirring frequency of 20 Hz, and a dispersion frequency of 35 Hz. Fumed silica was added and stirred and mixed for 20 minutes under a stirring frequency of 20 Hz and a dispersion frequency of 35 Hz. Phenyl silicone oil, silane coupling agent, and catalyst were added and stirred and mixed for 20 minutes under a vacuum of -0.1 MPa, a stirring frequency of 25 Hz, and a dispersion frequency of 30 Hz. The mixture was then discharged and filled to obtain a high-temperature resistant silicone sealant product.

[0032] Example 3 Preparation of a high-temperature resistant silicone sealant: 1. The raw materials are composed of the following parts by weight: 100 parts of hydroxyl-terminated polymethylphenylsiloxane, 30 parts of low-melting-point glass powder, 4 parts of fumed silica, 5 parts of phenyl silicone oil, 8 parts of ferric oxide, 8 parts of crosslinking agent, 2 parts of silane coupling agent, and 0.1 parts of di-n-butyltin diacetate. The hydroxyl-terminated polymethylphenylsiloxane has a viscosity of 30,000 mPa·s at 25°C and a phenyl molar fraction of 10%; the phenyl silicone oil has a viscosity of 350 mPa·s and a phenyl molar fraction of 25%. The crosslinking agent is composed of 5 parts by weight of methyl tributanone oxime silane, 1 part by weight of vinyl tributanone oxime silane, and 2 parts by weight of phenyl tributanone oxime silane.

[0033] The silane coupling agent is composed of 1.2 parts by weight of γ-aminoethylaminopropyltrimethoxysilane and 0.8 parts by weight of hexamethyldisilazane.

[0034] 2. The preparation method is as follows: The hydroxyl-terminated polymethylphenylsiloxane, low-melting-point glass powder, and ferric oxide described above were stirred, kneaded, and dehydrated for 2 hours under a vacuum of -0.1 MPa and a temperature of 120±2℃ to prepare a base material with a water content of less than 0.05%, which was then cooled. The cooled base material and crosslinking agent were then stirred and mixed for 20 minutes under a vacuum of -0.09 MPa, a stirring frequency of 25 Hz, and a dispersion frequency of 30 Hz. Fumed silica was then added and stirred and mixed for 20 minutes under a stirring frequency of 25 Hz and a dispersion frequency of 35 Hz. Phenyl silicone oil, silane coupling agent, and catalyst were then added and stirred and mixed for 20 minutes under a vacuum of -0.09 MPa, a stirring frequency of 25 Hz, and a dispersion frequency of 30 Hz. The mixture was then discharged and filled to obtain a high-temperature resistant silicone sealant product.

[0035] Example 4 Preparation of a high-temperature resistant silicone sealant: 1. The raw materials are composed of the following parts by weight: 100 parts of hydroxyl-terminated polymethylphenylsiloxane, 30 parts of low-melting-point glass powder, 6 parts of fumed silica, 10 parts of phenyl silicone oil, 10 parts of ferric oxide, 8 parts of crosslinking agent, 2 parts of silane coupling agent, and 0.15 parts of di-n-butyltin diacetate. The hydroxyl-terminated polymethylphenylsiloxane has a viscosity of 20,000 mPa·s at 25°C and a phenyl molar fraction of 10%; the phenyl silicone oil has a viscosity of 100 mPa·s and a phenyl molar fraction of 30%. The crosslinking agent is 6 parts by weight of methyl tributanone oxime silane and 2 parts by weight of phenyl tributanone oxime silane.

[0036] The silane coupling agent is 1 part by weight of γ-aminoethylaminopropyltrimethoxysilane and 1 part by weight of hexamethyldisilazane.

[0037] 2. The preparation method is as follows: The hydroxyl-terminated polymethylphenylsiloxane, low-melting-point glass powder, and ferric oxide were stirred, kneaded, and dehydrated for 2 hours under a vacuum of -0.1 MPa and a temperature of 120±2℃ to prepare a base material with a water content of less than 0.05%, which was then cooled. The cooled base material and crosslinking agent were then stirred and mixed for 15 minutes under a vacuum of -0.09 MPa, a stirring frequency of 25 Hz, and a dispersion frequency of 35 Hz. Fumed silica was then added and stirred and mixed for 20 minutes under a stirring frequency of 20 Hz and a dispersion frequency of 35 Hz. Phenyl silicone oil, silane coupling agent, and catalyst were then added and stirred and mixed for 20 minutes under a vacuum of -0.1 MPa, a stirring frequency of 20 Hz, and a dispersion frequency of 35 Hz. The mixture was then discharged and filled to obtain the high-temperature resistant silicone sealant product.

[0038] Example 5 Preparation of a high-temperature resistant silicone sealant: 1. The raw materials are composed of the following parts by weight: 100 parts of hydroxyl-terminated polymethylphenylsiloxane, 40 parts of low-melting-point glass powder, 3 parts of fumed silica, 15 parts of phenyl silicone oil, 10 parts of ferric oxide, 9 parts of crosslinking agent, 3 parts of silane coupling agent, and 0.1 parts of di-n-butyltin diacetate. The hydroxyl-terminated polymethylphenylsiloxane has a viscosity of 20,000 mPa·s at 25°C and a phenyl molar fraction of 10%; the phenyl silicone oil has a viscosity of 100 mPa·s and a phenyl molar fraction of 30%. The crosslinking agent is 6 parts by weight of methyl tributanone oxime silane and 3 parts by weight of phenyl tributanone oxime silane.

[0039] The silane coupling agent is composed of 1.5 parts by weight of γ-aminoethylaminopropyltrimethoxysilane and 1.5 parts by weight of hexamethyldisilazane.

[0040] 2. The preparation method is as follows: The hydroxyl-terminated polymethylphenylsiloxane, low-melting-point glass powder, and ferric oxide were stirred, kneaded, and dehydrated for 2 hours under a vacuum of -0.1 MPa and a temperature of 120±2℃ to prepare a base material with a water content of less than 0.05%, which was then cooled. The cooled base material and crosslinking agent were stirred and mixed for 15 minutes under a vacuum of -0.09 MPa, a stirring frequency of 25 Hz, and a dispersion frequency of 35 Hz. Fumed silica was added and stirred and mixed for 20 minutes under a stirring frequency of 25 Hz and a dispersion frequency of 35 Hz. Phenyl silicone oil, silane coupling agent, and catalyst were added and stirred and mixed for 20 minutes under a vacuum of -0.1 MPa, a stirring frequency of 25 Hz, and a dispersion frequency of 35 Hz. The mixture was then discharged and filled to obtain a high-temperature resistant silicone sealant product.

[0041] Comparative Example 1 The technical solution of this comparative example is similar to that of Example 1, except that the initial melting point of the glass powder is 350°C and the particle size is 10 μm.

[0042] Comparative Example 2 The technical solution of this comparative example is similar to that of Example 1, except that the mass ratio of ferric oxide to low melting point glass powder is 15:30.

[0043] Comparative Example 3 The technical solution of this comparative example is similar to that of Example 1, except that the phenyl molar fraction of the phenyl silicone oil is 10%.

[0044] Comparative Example 4 The technical solution of this comparative example is similar to that of Example 1, except that the hydroxyl-terminated polymethylphenylsiloxane phenyl molar fraction is 15%.

[0045] Comparative Example 5 The technical solution of this comparative example is similar to that of Example 1, except that the low melting point glass powder is replaced with 6 μm modified nano-silica.

[0046] Comparative Example 6 The technical solution of this comparative example is similar to that of Example 1, except that the low melting point glass powder and ferric oxide are replaced with silane-modified graphene.

[0047] Performance testing The Shore hardness of the colloid was tested according to GB / T531; the surface drying time was tested according to GB / T13477.5; the extrusion ratio was tested according to GB / T13477; the volume resistivity was tested according to GB / T1692; the breakdown voltage was tested according to GB / T1695; the elongation at break and tensile strength were tested according to GB / T528; and the adhesion was tested according to GB / T15254. For temperature resistance testing: Samples were prepared according to the above standards, placed in an oven at 360℃ for 24 hours, and then cooled at room temperature for 24 hours. The Shore hardness, volume resistivity, breakdown voltage, tensile strength, elongation at break, and adhesion were then measured according to the above methods. The results were compared with test data from samples that had not undergone high-temperature aging. The performance retention rate was required to be above 80%.

[0048] Analysis and Explanation Table 1 shows that the surface drying time and extrusion rate of the sealants prepared in Examples 1-5 all meet the requirements of industrial construction operations at room temperature. The mechanical properties such as Shore hardness, tensile strength, and elongation at break, as well as the electrical properties such as volume resistivity and breakdown voltage, are all well-balanced. After high-temperature aging at 360℃ for 24 hours, the mechanical and electrical properties of each example retain more than 80%, and the area of ​​adhesive cohesive failure still remains above 95%. There are no obvious phenomena of adhesive layer hardening, cracking, or adhesive failure. This indicates that the raw material ratio, component selection, and preparation process specified in this invention can enable the sealant to maintain the stability of its structure and performance under high-temperature conditions of 300~360℃, fully meeting the requirements for high-temperature sealing.

[0049] Table 1 Performance indicators of the obtained silicone sealant

[0050] In Table 2, all comparative examples showed significant performance degradation after aging at 300℃ for 24 hours. Comparative Example 1 suffered from discontinuous film structure due to incomplete melting at high temperatures caused by mismatched initial melting point and particle size of the glass powder, leading to a sharp drop in performance and adhesion. Comparative Example 2 experienced filler agglomeration and hindered film formation due to an unsuitable weight ratio of glass powder to ferric oxide, damaging the high-temperature resistant framework. Comparative Examples 3 and 4 exhibited decreased high-temperature compatibility due to deviations in the phenyl molar fraction of phenyl silicone oil and hydroxyl-terminated polymethylphenylsiloxane, resulting in phase separation and filler agglomeration. Comparative Examples 5 and 6, by replacing the glass powder-ferric oxide composite filler system of this invention, lacked the core function of melting and forming a heat-resistant layer, leading to barrier layer damage and filler agglomeration at high temperatures, which became the main causes of performance failure.

[0051] Table 2. Performance retention rate of samples after high-temperature aging

[0052] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A high-temperature resistant silicone sealant, characterized in that, The raw materials include the following parts by weight: 100 parts of hydroxyl-terminated polymethylphenylsiloxane, 20-40 parts of glass powder, 3-6 parts of fumed silica, 5-15 parts of phenyl silicone oil, 5-10 parts of ferric oxide, 6-10 parts of crosslinking agent, 1-3 parts of silane coupling agent, and 0.05-0.15 parts of catalyst.

2. The high-temperature resistant silicone sealant according to claim 1, characterized in that, The hydroxyl-terminated polymethylphenylsiloxane has a phenyl molar fraction of 8% to 12%; the phenyl silicone oil has a phenyl molar fraction of 20% to 30%.

3. The high-temperature resistant silicone sealant according to claim 1, characterized in that, The ratio of the phenyl molar fraction of the phenyl silicone oil to the phenyl molar fraction of the hydroxyl-terminated polymethylphenylsiloxane is 2 to 3:

1.

4. The high-temperature resistant silicone sealant according to claim 1, characterized in that, The weight ratio of glass powder to ferric oxide is 2:1 to 8:

1.

5. The high-temperature resistant silicone sealant according to claim 1, characterized in that, The median particle size D50 of the glass powder is 4–8 μm; the median particle size D50 of the ferric oxide is 3–5 μm.

6. The high-temperature resistant silicone sealant according to claim 1, characterized in that, The initial melting point of the glass powder is 300-340℃.

7. The high-temperature resistant silicone sealant according to claim 1, characterized in that, The fumed silica has a particle size of 30 nm to 40 nm and a specific surface area of ​​300 to 400 m². 2 / g.

8. A method for preparing the high-temperature resistant silicone sealant according to any one of claims 1 to 7, characterized in that, The process includes the following steps: heating and dehydrating hydroxyl-terminated polymethylphenylsiloxane, glass powder, and ferric oxide under vacuum to obtain a base material with a water content of less than 0.05% and then cooling it; adding a crosslinking agent to the cooled base material and mixing it evenly; then adding fumed silica; and then adding phenyl silicone oil, silane coupling agent, and catalyst and stirring and mixing evenly to obtain the high-temperature resistant silicone sealant.

9. The application of the high-temperature resistant silicone sealant according to any one of claims 1 to 7 in sealing and bonding at an environment of 300 to 360°C.

10. The application of the high-temperature resistant silicone sealant according to claim 9, characterized in that, The application is for sealing new energy equipment, high-temperature pipelines, industrial furnaces, sensors, and high-temperature cooking appliances.

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