Addition type heat-resistant silicone rubber composite material, preparation method and application

Abstract

The application discloses an addition type heatproof silicone rubber composite material, a preparation method and application. The addition type heatproof silicone rubber composite material comprises the following components in parts by weight: 100 parts of vinyl silicone oil, 20-50 parts of branched vinyl phenyl polysiloxane, 30-50 parts of fumed white carbon black, 20-30 parts of fiber filler, 10-20 parts of flame-retardant filler, 10-30 parts of hydrogen-containing silicone oil and 1-5 parts of platinum catalyst. The branched vinyl phenyl polymer is introduced into the addition type silicone rubber system, the branched structure has a plurality of vinyl active sites and low viscosity characteristics, the addition type heatproof material system has good mechanical strength, flexibility and thermal stability, the reinforcing filler and the flame-retardant filler can be reduced, the mechanical properties of the material are improved, the density is further reduced, the research direction of high strength, low density and high ablation resistance of the heat protection material is met, and the application has a wide prospect in the field of solid rocket engine heat protection materials.

Description

Technical Field

[0001] This invention relates to the field of thermal protection materials for aerospace vehicles, and in particular to an addition-type heat-resistant silicone rubber composite material, its preparation method, and its application. Background Technology

[0002] Silicone rubber-based heat-resistant coatings belong to the category of silicon-based heat-resistant materials. They possess advantages such as low density, high heat-resistant efficiency, and simple construction, and are widely used in the aerospace field. Addition-cure silicone rubber cures rapidly, does not release small-molecule gases, and has advantages such as good shrinkage resistance and deep curing capability. Considering both material properties and curing efficiency, addition-cure silicone rubber systems are more preferred for silicon-based external heat-resistant materials. Addition-cure silicone-based external heat-resistant materials consist of components such as a base polymer, vulcanization crosslinking agent, reaction inhibitor, catalyst, and reinforcing filler.

[0003] With the development of aircraft, future hypersonic aircraft will place even more stringent demands on the performance of silicone rubber heat-resistant materials. The application environment requires silicone rubber to possess good mechanical strength, heat resistance, and erosion resistance, as well as a sufficiently low density. The overall performance of silicone rubber heat-resistant materials urgently needs improvement.

[0004] Currently, the polysiloxanes used in silicone rubber heat-resistant materials are mainly linear polysiloxanes, with other structures being used less frequently. However, in fact, many polysiloxanes with special structures have been synthesized, including (hyper)branched structures, trapezoidal structures, and POSS structures. Summary of the Invention

[0005] Addressing the problems of limited crosslinking points, high viscosity, poor mechanical properties after curing, and mediocre ablation resistance associated with the linear structure of traditional polysiloxanes, this invention aims to provide an addition-cured heat-resistant silicone rubber composite material, its preparation method, and its application. From a polymer chemistry perspective, a multi-branched, multi-functional organosilicon polymer is designed to increase the number of active functional groups and crosslinking points. Introducing this into an addition-cured heat-resistant material system can significantly improve mechanical properties and also enhance the material's ablation resistance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an addition-type heat-resistant silicone rubber composite material, comprising the following components in parts by weight: 100 parts of vinyl silicone oil, 20-50 parts of branched vinylphenyl polysiloxane, 30-50 parts of fumed silica, 20-30 parts of fiber filler, 10-20 parts of flame-retardant filler, 10-30 parts of hydrogen-containing silicone oil, and 1-5 parts of platinum catalyst.

[0007] In some possible embodiments, the branched vinylphenyl polysiloxane has the following structural formula: , The schematic diagram of the D linker structure is as follows: .

[0008] In some possible implementations, the fiber filler is one or more of carbon fiber, quartz fiber, aramid fiber, glass fiber, and silicate fiber.

[0009] In a second aspect, the present invention provides a method for preparing the addition-cured heat-resistant silicone rubber composite material according to any one of the first aspects, comprising the following steps: The vinyl silicone oil is mixed with reinforcing filler to obtain a base rubber; The branched vinylphenyl polysiloxane, fiber filler and flame retardant filler are mixed and premixed by internal mixing to obtain premixed filler; The base rubber and premixed filler are blended and mixed to prepare component A of the addition-type silicone rubber thermal protection material; The addition-type silicone rubber thermal protection material component A is mixed with hydrogen-containing silicone oil and platinum catalyst to form a three-component material, which is then vulcanized after being blended in a certain proportion to obtain the addition-type heat-resistant silicone rubber composite material.

[0010] In some possible implementations, the vinyl silicone oil and reinforcing filler are mixed to obtain the base rubber, specifically by: placing the vinyl silicone oil and reinforcing filler in a dynamic mixer, setting the temperature to 80-120℃, vacuuming at a negative pressure of 0.08~0.10MPa for 2-4 hours, and rotating at a speed of 30-80 r / min to obtain the base rubber.

[0011] In some possible implementations, the branched vinylphenyl polysiloxane, fiber filler, and flame retardant filler are mixed and premixed by internal mixing to obtain the premixed filler. Specifically, this involves placing the branched vinylphenyl polysiloxane, fiber filler, and flame retardant filler in a dynamic mixer, setting the temperature to 80-120℃, evacuating under a negative pressure of 0.08~0.10MPa for 1-3 hours, and rotating at a speed of 30-80r / min to obtain the premixed filler.

[0012] In some possible implementations, the preparation of component A of the addition-type silicone rubber thermal protection material by blending and mixing the base rubber and premixed filler specifically includes: stirring the base rubber and premixed filler in a dynamic mixer at room temperature for 0.5-2 hours at a speed of 30-50 r / min.

[0013] In some possible implementations, the addition-cure silicone rubber thermal protection material component A, hydrogen-containing silicone oil, and platinum catalyst form a three-component material. After blending in a certain proportion, the curing process specifically includes: mixing the addition-cure silicone rubber thermal protection material component A, hydrogen-containing silicone oil, and platinum catalyst at a vinyl:hydrogen molar ratio of 1:1-1.2, with the platinum catalyst accounting for 0.3-1.5% of the addition-cure silicone rubber thermal protection material component A, followed by vacuum degassing, curing, and setting the curing temperature to 60-120°C and the curing time to 2-24 hours.

[0014] Thirdly, the present invention also provides an application of the addition-cured heat-resistant silicone rubber composite material according to any one of the first aspects, wherein the addition-cured heat-resistant silicone rubber composite material can be used in thermal protection materials for spacecraft.

[0015] This invention provides an addition-cure heat-resistant silicone rubber composite material, its preparation method, and its application. It introduces a branched vinylphenyl polymer into the addition-cure silicone rubber system. Due to the multiple vinyl active sites and low viscosity characteristics obtained from its branched structure, it possesses excellent mechanical strength, flexibility, and thermal stability. This reduces the need for reinforcing fillers and flame-retardant fillers in addition-cure external heat-resistant material systems, thereby improving the material's mechanical properties and further reducing its density. This aligns with the current research trend of high-strength, low-density, and high ablation resistance in thermal protection materials, and has broad prospects in the field of solid rocket motor thermal protection materials. Attached Figure Description

[0016] Figure 1 A schematic diagram of the structure of branched vinylphenyl polysiloxane; Figure 2 A schematic diagram of the D-unit structure in the structure of branched vinylphenyl polysiloxane; Figure 3 This is the infrared spectrum of branched vinylphenyl polysiloxane. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. At the same time, in the description of the embodiments of this application, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0018] Example 1 This embodiment provides an addition-cured heat-resistant silicone rubber composite material, comprising the following components in parts by weight: 100 parts vinyl silicone oil, 20 parts branched vinylphenyl polysiloxane, 30 parts fumed silica, 30 parts carbon fiber, 10 parts magnesium silicate, 15 parts hydrogen-containing silicone oil, and 2 parts platinum catalyst, wherein the structure of the branched vinylphenyl polysiloxane is as follows: Figure 1 , 2 As shown, its infrared spectrum is as follows Figure 3 As shown.

[0019] Addition-cured heat-resistant silicone rubber composites can be used in thermal protection materials for spacecraft. Their preparation method includes the following steps: Vinyl silicone oil and reinforcing filler were mixed. The vinyl silicone oil and reinforcing filler were placed in a dynamic mixer, the temperature was set at 120℃, the vacuum was drawn for 2 hours under a negative pressure of 0.09MPa, and the rotation speed was 50r / min to obtain the base rubber. Branched vinylphenyl polysiloxane, fiber filler and flame retardant filler are mixed and premixed by internal mixing. The branched vinylphenyl polysiloxane, fiber filler and flame retardant filler are placed in a dynamic mixer, the temperature is set to 120℃, the vacuum is evacuated for 1h under a negative pressure of 0.09MPa and the rotation speed is 30 r / min to obtain the premixed filler. The base rubber and premixed filler were stirred at room temperature for 0.5 hours in a dynamic mixer at a speed of 50 r / min to prepare component A of the addition-type silicone rubber thermal protection material; The addition-cure silicone rubber thermal protection material component A was mixed with hydrogen-containing silicone oil and platinum catalyst at a vinyl:hydrogen molar ratio of 1:1.2, with the platinum catalyst accounting for 1.0% of the addition-cure silicone rubber thermal protection material component A. The mixture was degassed under vacuum, poured into a mold with dimensions of 100mm long × 100mm wide × 3mm high, leveled, and then vulcanized. The vulcanization temperature was set at 80℃ and the vulcanization time was 12h to obtain the addition-cure heat-resistant silicone rubber composite material.

[0020] Example 2 The only difference between this embodiment and Embodiment 1 is that an addition-type heat-resistant silicone rubber composite material, by weight, includes the following components in parts by weight: 100 parts vinyl silicone oil, 30 parts branched vinyl phenyl polysiloxane, 20 parts fumed silica, 10 parts aramid fiber, 10 parts carbon fiber, 15 parts aluminum hydroxide, 20 parts hydrogen-containing silicone oil, and 1.5 parts platinum catalyst.

[0021] Example 3 The only difference between this embodiment and Embodiment 1 is that an addition-type heat-resistant silicone rubber composite material, by weight, includes the following components in parts by weight: 100 parts vinyl silicone oil, 50 parts branched vinyl phenyl polysiloxane, 30 parts fumed silica, 30 parts quartz fiber, 10 parts magnesium silicate, 30 parts hydrogen-containing silicone oil, and 3 parts platinum catalyst.

[0022] Comparative Example 1 The only difference between this comparative example and Example 3 is that the addition-type heat-resistant silicone rubber composite material comprises the following components in parts by weight: 150 parts vinyl silicone oil, 30 parts fumed silica, 30 parts quartz fiber, 10 parts magnesium silicate, 30 parts hydrogen-containing silicone oil, and 3 parts platinum catalyst.

[0023] Comparative Example 2 The only difference between this comparative example and Example 2 is that the preparation method includes the following steps: 100 g of vinyl silicone oil, 30 g of branched vinylphenyl polysiloxane, 20 g of fumed silica, 10 g of aramid fiber, 10 g of carbon fiber, and 15 g of aluminum hydroxide are added to a dynamic mixer and mixed evenly. The temperature is set at 120°C, and a vacuum is drawn under a negative pressure of 0.09 MPa for 2 hours. Then, the pressure is released, 20 g of hydrogen-containing silicone oil and 1.5 g of platinum catalyst are added, and the mixture is stirred rapidly for 30 minutes to mix evenly. After vacuum degassing, a 3 mm thick sample is made and then vulcanized. The vulcanization temperature is set at 80°C and the vulcanization time is 12 hours to obtain an addition-cured heat-resistant silicone rubber composite material.

[0024] The tests conducted on Examples 1-3 and Comparative Examples 1-2 are shown in Table 1: Table 1 Comparing the properties of the materials obtained in Examples 1-3 with those in Comparative Examples 1-2, it is evident that branched vinylphenyl polysiloxane significantly enhances the mechanical properties of the addition-type silicone rubber heat-resistant material system. Example 2 and Comparative Example 2 used the same formulation but different preparation processes. Example 2, with a tensile strength of 3.8 MPa, showed a significant difference in mechanical properties compared to Comparative Example 2's 2.5 MPa. This difference may be due to the fact that premixing branched vinylphenyl polysiloxane with fiber fillers and flame-retardant fillers improves the compatibility between the fillers and the base rubber system, aiding in filler dispersion. Minor differences in density may be due to defects in the samples.

[0025] A comparison of the performance of addition-type silicone rubber heat-resistant materials with and without branched vinylphenyl polysiloxane in Example 3 and Comparative Example 1 revealed that, under the same filler system and preparation process, the group with branched vinylphenyl polysiloxane exhibited significantly higher mechanical properties and ablation resistance than Comparative Example 1. As mentioned earlier, branched vinylphenyl polysiloxane possesses functional groups with excellent vinyl and phenyl temperature resistance, which can improve the thermal stability of the silicone rubber system. Furthermore, its branched telechelicerae are all active vinyl groups, which can participate in crosslinking reactions, thereby enhancing the material's mechanical properties and comprehensively improving the application performance of addition-type heat-resistant materials.

[0026] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. An addition-cured heat-resistant silicone rubber composite material, characterized in that, The product comprises the following components in parts by weight: 100 parts vinyl silicone oil, 20-50 parts branched vinyl phenyl polysiloxane, 30-50 parts fumed silica, 20-30 parts fiber filler, 10-20 parts flame retardant filler, 10-30 parts hydrogen-containing silicone oil, and 1-5 parts platinum catalyst. The branched vinylphenyl polysiloxane is prepared by hydrolysis copolymerization of a trifunctional silane monomer and a phenyl vinyl silicone oil under acidic or alkaline conditions, wherein the trifunctional silane monomer is a trimethoxysilane or a triethoxysilane, and the R group is one of C1-C8 alkyl, phenyl, vinyl, amino, and epoxy groups.

2. The addition-cured heat-resistant silicone rubber composite material according to claim 1, characterized in that: The structural formula of the branched vinylphenyl polysiloxane is shown below: ， The schematic diagram of the D linker structure is as follows: .

3. The addition-cured heat-resistant silicone rubber composite material according to claim 1, characterized in that, The fiber filler is one or more of carbon fiber, quartz fiber, aramid fiber, glass fiber, and silicate fiber.

4. A method for preparing an addition-cured heat-resistant silicone rubber composite material according to any one of claims 1-3, characterized in that, Includes the following steps: The vinyl silicone oil is mixed with reinforcing filler to obtain a base rubber; The branched vinylphenyl polysiloxane, fiber filler and flame retardant filler are mixed and premixed by internal mixing to obtain premixed filler; The base rubber and premixed filler are blended and mixed to prepare component A of the addition-type silicone rubber thermal protection material; The addition-type silicone rubber thermal protection material component A is mixed with hydrogen-containing silicone oil and platinum catalyst to form a three-component material, which is then vulcanized after being blended in a certain proportion to obtain the addition-type heat-resistant silicone rubber composite material.

5. The preparation method according to claim 4, characterized in that, The specific steps for obtaining the base rubber by mixing the vinyl silicone oil and reinforcing filler include: placing the vinyl silicone oil and reinforcing filler in a dynamic mixer, setting the temperature to 80-120℃, vacuuming under a negative pressure of 0.8-1.0MPa for 2-4 hours, and rotating at a speed of 30-80r / min to obtain the base rubber.

6. The preparation method according to claim 4, characterized in that, The branched vinylphenyl polysiloxane, fiber filler, and flame retardant filler are mixed and premixed in an internal mixer to obtain the premixed filler. Specifically, the branched vinylphenyl polysiloxane, fiber filler, and flame retardant filler are placed in a dynamic mixer, the temperature is set to 80-120℃, the vacuum is evacuated for 1-3 hours under a negative pressure of 0.8-1.0MPa, and the rotation speed is 30-80r / min to obtain the premixed filler.

7. The preparation method according to claim 4, characterized in that, The preparation of component A of the addition-type silicone rubber thermal protection material by blending and mixing the base rubber and premixed filler specifically includes: stirring the base rubber and premixed filler in a dynamic mixer at room temperature for 0.5-2 hours at a speed of 30-50 r / min.

8. The preparation method according to claim 4, characterized in that, The addition-cure silicone rubber thermal protection material component A, hydrogen-containing silicone oil, and platinum catalyst form a three-component material. After blending in a certain proportion, the curing process specifically includes: the addition-cure silicone rubber thermal protection material component A, hydrogen-containing silicone oil, and platinum catalyst are mixed at a vinyl:hydrogen molar ratio of 1:1-1.2, with the platinum catalyst accounting for 0.3-1.5% of the addition-cure silicone rubber thermal protection material component A. After mixing, vacuum degassing and curing are performed. The curing temperature is set at 60-120℃, and the curing time is 2-24 hours.

9. The application of the addition-cured heat-resistant silicone rubber composite material according to any one of claims 1-3, characterized in that, The addition-type heat-resistant silicone rubber composite material can be used in thermal protection materials for spacecraft.

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