High temperature resistant mixing silicone rubber and preparation method thereof

Abstract

The application relates to the technical field of silicone rubber, and particularly discloses a high-temperature-resistant mixing silicone rubber and a preparation method thereof. Through the synergistic effect of rigid groups, a crosslinking network structure and lignin nano-modified silicon dioxide, the main chain degradation reaction of the mixing silicone rubber caused by high temperature can be sufficiently weakened, so that the mixing silicone rubber has better thermal stability, can maintain good mechanical properties after high-temperature treatment, and has a wide application range.

Description

Technical Field

[0001] This application relates to the field of silicone rubber technology, and more specifically, to a high-temperature resistant compounded silicone rubber and its preparation method. Background Technology

[0002] Silicone rubber is a type of polymeric elastomer material with repeating silicon-oxygen bonds as the main chain and organic groups (mainly methyl, vinyl, or phenyl) attached to the side chains. Its unique molecular structure endows it with excellent comprehensive properties. The advantages of silicone rubber include excellent flexibility and elasticity, a wide operating temperature range (typically -60℃ to +200℃), excellent weather resistance (UV and ozone resistance), good electrical insulation, physiological inertness, and low surface tension.

[0003] Thanks to its inherent superior properties, silicone rubber has become an indispensable key material in numerous industrial sectors and daily life. In the aerospace industry, silicone rubber is used in engine compartment seals, hot air ducts, and gaskets; in the automotive industry, it is used in engine peripheral seals (such as cylinder head gaskets), turbocharger hoses, and ignition cable sheaths; in the electronics and electrical industry, it is used in wire and cable insulation, connector seals, and thermally conductive gaskets. Furthermore, silicone rubber also plays an important role in household appliances and medical devices.

[0004] Regarding the aforementioned technologies, the inventors believe that although silicone rubber has a certain tolerance to high temperatures, when the temperature exceeds 300℃, thermal degradation will have a serious impact on the structure of silicone rubber, leading to a decrease in the mechanical properties of silicone rubber and limiting the application range of silicone rubber. Summary of the Invention

[0005] In related technologies, when the temperature exceeds 300℃, thermal degradation severely affects the structure of silicone rubber, leading to a decrease in its mechanical properties and limiting its application range. To improve this deficiency, this application provides a high-temperature resistant compounded silicone rubber and its preparation method.

[0006] In the first aspect, this application provides a high-temperature resistant compounded silicone rubber, which adopts the following technical solution:

[0007] A high-temperature resistant compounded silicone rubber comprises the following components in parts by weight: 40-45 parts modified methyl vinyl silicone rubber, 10-15 parts methyl phenyl silicone rubber, 10-15 parts vinyl MQ silicone resin, 3-5 parts structure control agent, 3.5-4.5 parts filler, and 2.0-2.5 parts vulcanizing agent; wherein the modified methyl vinyl silicone rubber contains polyimide groups and lignin groups; and wherein the filler comprises lignin-modified nano silica.

[0008] By adopting the above technical solution, this application uses modified methyl vinyl silicone rubber and methyl phenyl silicone rubber as the main components. The modified methyl phenyl silicone rubber contains rigid lignin groups and polyimide groups, and the methyl phenyl silicone rubber contains rigid benzene rings. These rigid groups can hinder the molecular chain movement of the compounded silicone rubber. Vinyl MQ silicone resin can be uniformly dispersed in the compounded silicone rubber and can participate in vulcanization during the vulcanization process, undergoing further crosslinking on the basis of the silicone rubber. The new crosslinked network structure can synergistically hinder the molecular chain movement of the compounded silicone rubber with the rigid groups introduced into the compounded silicone rubber. The lignin groups on the surface of the lignin-modified nano-silica in the filler can synergistically hinder the molecular chain movement of the compounded silicone rubber with the lignin groups in the modified methyl vinyl silicone rubber. Furthermore, the good thermal conductivity of silica itself also promotes the uniform distribution of heat, reducing the possibility of localized high-temperature accumulation. Through the synergistic effect of rigid groups, cross-linked network structure and lignin nano-modified silica, the main chain degradation reaction of the compounded silicone rubber under high temperature can be fully weakened, thus possessing better thermal stability and maintaining good mechanical properties after high temperature treatment, and having a wide range of applications.

[0009] Preferably, the structuring control agent is one of hydroxyl silicone oil, dimethyldiethoxysilane, or hexamethyldisilazane.

[0010] By adopting the above technical solution, this application has selected the type of structure control agent. Compared with the other two structure control agents, the more rigid hexamethyldisilazane can produce a good synergistic effect with the rigid groups in the modified methyl vinyl silicone rubber, methyl phenyl silicone rubber and other components, thereby effectively improving the high temperature resistance of the compounded silicone rubber and enabling the compounded silicone rubber to maintain good mechanical properties after high temperature treatment.

[0011] Preferably, the vinyl MQ silicone resin has a vinyl molar fraction of 0.13-0.17%.

[0012] By adopting the above technical solution, this application has optimized the range of vinyl molar fraction of vinyl MQ silicone resin, which can fully promote the crosslinking of vinyl MQ silicone resin and silicone rubber molecules, effectively improve the high temperature resistance of the compounded silicone rubber, and enable the compounded silicone rubber to maintain good mechanical properties after high temperature treatment.

[0013] Preferably, the modified methyl vinyl silicone rubber is prepared according to the following method:

[0014] (1) Mix methyl vinyl silicone rubber with toluene until uniform, add dimethyl chlorosilane to the mixture, stir and heat under nitrogen protection, add platinum catalyst, continue to keep the reaction at the temperature, then cool down and discharge the material. After purification and post-treatment, silicone rubber intermediate material is obtained.

[0015] (2) Add the silicone rubber intermediate to tetrahydrofuran and stir to dissolve. Then add hydroxyethylated lignin, hydroxyl-containing polyimide and acid binder. Stir and heat at a constant temperature under nitrogen protection. After the reaction is completed, discharge the material and then wash and vacuum dry to obtain modified methyl vinyl silicone rubber.

[0016] By adopting the above technical solution, this application first uses dimethylchlorosilane and methyl vinyl silicone rubber as reactants, and a hydrosilylation reaction is carried out under the catalysis of a platinum catalyst to obtain a chlorine-containing silicone rubber intermediate. Then, in the presence of an acid binder, the silicone rubber intermediate undergoes a coupling grafting reaction with hydroxyethylated lignin and hydroxyl-containing polyimide. The silicone rubber intermediate loses chlorine atoms, and the lignin groups and polyimide groups are grafted onto the main chain of the silicone rubber, thereby obtaining modified methyl vinyl silicone rubber.

[0017] Preferably, the hydroxyl-containing polyimide is prepared according to the following method:

[0018] After mixing diamine monomer, dianhydride monomer and m-cresol, isoquinoline was added dropwise to the mixture, and then the mixture was heated under nitrogen protection to obtain a reaction solution. The reaction solution was cooled, and excess ethanol was added to precipitate the mixture. After vacuum filtration and washing, hydroxyl-containing polyimide was obtained; the diamine monomer contained phenolic hydroxyl groups.

[0019] By adopting the above technical solution, this application uses a diamine monomer containing phenolic hydroxyl groups to react with a dianhydride monomer to obtain a hydroxyl-containing polyimide.

[0020] Preferably, the diamine monomer is 3,3'-dihydroxybenzidine or 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane.

[0021] By adopting the above technical solutions, this application has selected two diamine monomers containing hydroxyl groups, which can be used to prepare hydroxyl-containing polyimides.

[0022] Preferably, the dianhydride monomer is selected from 4,4'-(4,4'-isopropyldiphenoxy) phthalic anhydride, 4,4'-(hexafluoroisopropene) phthalic anhydride, or 4,4'-oxophthalic anhydride.

[0023] By adopting the above technical solutions, this application has selected three dianhydride monomers that can be used to prepare hydroxyl-containing polyimides.

[0024] Preferably, the hydroxyethylated lignin is prepared according to the following method:

[0025] Enzymatically hydrolyzed lignin, ethylene carbonate, and tetrabutylammonium iodide were mixed and stirred to obtain a reaction mixture. Ethanol was added to the reaction mixture to obtain a diluted mixture. The diluted mixture was added to hydrochloric acid, and then the reaction was carried out under freezing conditions. After the reaction was completed, the mixture was filtered and the residue was collected. The residue was washed and freeze-dried to obtain hydroxyethylated lignin.

[0026] By adopting the above technical solution, this application uses ethylene carbonate as an alkylating agent and tetrabutylammonium iodide as an ionic liquid solvent and catalyst to hydroxyethylate enzymatically hydrolyzed lignin, obtaining hydroxyethylated lignin. In hydroxyethylated lignin, some phenolic hydroxyl groups are converted into alcoholic hydroxyl groups, which can more fully undergo coupling grafting reactions with silicone rubber intermediates, thus helping to improve the high-temperature resistance of the compounded silicone rubber.

[0027] Preferably, the lignin-modified nano-silica is prepared according to the following method:

[0028] Sodium silicate, alkali lignin, and deionized water were mixed and stirred to dissolve. Then, deionized water, ethanol, and polyethylene glycol were added and stirred. Sulfuric acid was added for acidification, and the mixture was stirred to obtain a nano-silica suspension. The nano-silica suspension was ultrasonically treated and preheated. Sulfuric acid was added again for acidification, followed by static treatment. The solid product was collected by vacuum filtration, and after acid washing and drying, lignin-modified nano-silica was obtained.

[0029] By adopting the above technical solution, this application uses sodium silicate as the silicon source and employs a two-step acid precipitation method to hybridize and modify lignin, thus preparing lignin-modified nano-silica. The lignin groups on the surface of the lignin-modified nano-silica can synergistically hinder the movement of the molecular chains of the compounded silicone rubber with the lignin groups in the modified methyl vinyl silicone rubber. Furthermore, the excellent thermal conductivity of silica itself promotes the uniform distribution of heat, reduces the possibility of localized high-temperature accumulation, and improves the high-temperature resistance of the compounded silicone rubber.

[0030] Secondly, this application provides a method for preparing high-temperature resistant compounded silicone rubber, using the following technical solution.

[0031] A method for preparing a high-temperature resistant compounded silicone rubber includes the following steps:

[0032] (1) Modified methyl vinyl silicone rubber, methyl phenyl silicone rubber, structural control agent and vinyl MQ silicone resin are placed in a two-roll mill for mixing. Fillers and vulcanizing agents are added during the mixing process. After mixing, the mixture is sheeted out to form a compound.

[0033] (2) Add the compounded rubber to a flat vulcanizing machine for vulcanization, and then wait for it to cool naturally to obtain high temperature resistant compounded silicone rubber.

[0034] By adopting the above technical solution, this application first mixes the components uniformly through compounding to obtain a compound rubber, and then further vulcanizes the compound rubber through a flat vulcanizing machine. During vulcanization, the vinyl MQ silicone resin undergoes further crosslinking on the basis of silicone rubber. The new crosslinking network structure can work synergistically with the rigid groups introduced into the compound silicone rubber to hinder the movement of the compound silicone rubber molecular chains, thus obtaining a compound silicone rubber with strong high temperature resistance.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. Through the synergistic effect of rigid groups, cross-linked network structure and lignin nano-modified silica, the main chain degradation reaction of the compounded silicone rubber under high temperature can be fully weakened, thus possessing better thermal stability and maintaining good mechanical properties after high temperature treatment, and having a wide range of applications.

[0037] 2. This application prefers the type of structure control agent, wherein hexamethyldisilazane can produce a good synergistic effect with the rigid groups in the modified methyl vinyl silicone rubber, methyl phenyl silicone rubber and other components, thereby effectively improving the high temperature resistance of the compounded silicone rubber, so that the compounded silicone rubber can maintain good mechanical properties after high temperature treatment. Detailed Implementation

[0038] The present application will be further described in detail below with reference to the embodiments, preparation examples and comparative examples. The raw materials involved in the present application can all be obtained commercially.

[0039] Preparation example of modified methyl vinyl silicone rubber

[0040] The following explanation uses Preparation Example 1 as an example.

[0041] Preparation Example 1

[0042] In this preparation example, the molecular weight of the methyl vinyl silicone rubber was 550,000, and the vinyl content was 0.17 mol%. The platinum catalyst was chloroplatinic acid. The diamine monomer was 3,3'-dihydroxybenzidine, and the dianhydride monomer was 4,4'-(4,4'-isopropyldiphenoxy)phthalic anhydride. The hydroxyl content of the enzymatically hydrolyzed lignin was 2.04 mmol / g, and the carboxyl content was 1.12 mmol / g.

[0043] In this preparation example, the hydroxyl-containing polyimide was prepared according to the following method:

[0044] 40 mmol of diamine monomer, 40 mmol of dianhydride monomer and 200 mL of m-cresol were mixed, and 2 mL of isoquinoline was added dropwise to the mixture. The mixture was then heated under nitrogen protection. During the reaction, the temperature was first maintained at room temperature for 2 h, then raised to 100 °C and held for 4 h, and then raised to 190 °C and held for 12 h to obtain the reaction solution. The reaction solution was cooled to 100 °C and then added to excess ethanol for precipitation. After vacuum filtration and washing, hydroxyl-containing polyimide was obtained.

[0045] In this preparation example, hydroxyethylated lignin was prepared according to the following method:

[0046] 20g of enzymatically hydrolyzed lignin, 12g of ethylene carbonate, and 48g of tetrabutylammonium iodide were mixed and stirred at 110℃ for 48h to obtain a reaction mixture. After cooling, 200mL of ethanol was added to the reaction mixture to obtain a diluted mixture. The diluted mixture was added to 700mL of hydrochloric acid with pH 2, and then the reaction was carried out under freezing conditions for 2h. After the reaction was completed, the mixture was filtered and the residue was collected. The residue was washed and freeze-dried to obtain hydroxyethylated lignin.

[0047] This preparation example provides a modified methyl vinyl silicone rubber, prepared according to the following method:

[0048] (1) Mix 80g of methyl vinyl silicone rubber with 150g of toluene evenly, add 3g of dimethyl chlorosilane to the mixture, stir and heat to 70°C under nitrogen protection, add 0.1g of platinum catalyst, continue to keep the reaction at the temperature for 9h, then cool down and discharge the material. Remove toluene by vacuum distillation under -95kPa and 65°C to obtain silicone rubber intermediate material.

[0049] (2) Add 80g of silicone rubber intermediate material to 300g of tetrahydrofuran and stir to dissolve. Then add 8g of hydroxyethylated lignin and 5g of hydroxyl-containing polyimide. Add triethylamine as an acid-binding agent. Stir and heat at 65°C for 6 hours under nitrogen protection. After the reaction is completed, discharge the material and then wash and vacuum dry to obtain modified methyl vinyl silicone rubber.

[0050] Preparation Example 2

[0051] The difference between this preparation example and Preparation Example 1 is that the diamine monomer used is 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane.

[0052] Preparation Example 3

[0053] The difference between this preparation example and Preparation Example 2 is that the dianhydride monomer used is 4,4'-(hexafluoroisopropene) phthalic anhydride.

[0054] Preparation Example 4

[0055] The difference between this preparation example and preparation example 3 is that the dianhydride monomer used is 4,4'-oxophthalic anhydride.

[0056] Preparation example of lignin-modified nano silica

[0057] The following explanation uses Preparation Example 5 as an example.

[0058] Preparation Example 5

[0059] In this preparation example, lignin-modified nano-silica was prepared according to the following method:

[0060] 59g sodium silicate nonahydrate, 12.5g alkali lignin, and 350mL deionized water were mixed and stirred to dissolve. Then, 200mL deionized water, 200mL ethanol, and 2.5g polyethylene glycol (PEG-2000) were added and stirred. Then, 1mol / L sulfuric acid was added for acidification. After stirring, a nano silica suspension with a pH of 9.5 was obtained. The nano silica suspension was ultrasonically treated for 20min, preheated at 70℃ for 20min, and then acidified again with 1mol / L sulfuric acid to adjust the pH to 2. After standing for 2h, the solid product was collected by vacuum filtration. After acid washing and drying, lignin-modified nano silica was obtained.

[0061] Example

[0062] Examples 1-3

[0063] The following description uses Example 1 as an example.

[0064] Example 1

[0065] In this embodiment, the modified methyl vinyl silicone rubber was prepared according to the method of Preparation Example 1. The molar ratio of phenyl to silicon atoms in the methyl phenyl silicone rubber was 0.18, the vinyl molar fraction of the vinyl MQ silicone resin was 0.10%, the structuring control agent was hydroxyl silicone oil, the filler was the lignin-modified nano silica of Preparation Example 5, and the vulcanizing agent was 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0066] This embodiment provides a high-temperature resistant compounded silicone rubber, comprising the following components in parts by weight: 40g modified methyl vinyl silicone rubber, 10g methyl phenyl silicone rubber, 10g vinyl MQ silicone resin, 3g structuring control agent, 3.5g filler, and 2.0g vulcanizing agent.

[0067] This embodiment provides a method for preparing high-temperature resistant compounded silicone rubber, including the following steps:

[0068] (1) The modified methyl vinyl silicone rubber, methyl phenyl silicone rubber, structural control agent and vinyl MQ silicone resin are placed in a two-roll mill and mixed at 40°C for 4 hours. The temperature is raised to 120°C and mixed for another 2 hours. The temperature is lowered to 40°C, filler and vulcanizing agent are added and plasticized for another 2 hours. After mixing, the mixture is sheeted out to form a compound.

[0069] (2) Add the compounded rubber to the flat vulcanizing machine, set the pressure to 25MPa and the temperature to 160℃, and then vulcanize. After vulcanizing for 10 minutes, take it out and wait for it to cool naturally to obtain high temperature resistant compounded silicone rubber.

[0070] As shown in Table 1, the main difference between Examples 1-3 lies in the different raw material ratios of the compounded silicone rubber.

[0071] Table 1 Raw material ratio of compounded silicone rubber

[0072]

[0073] Example 4

[0074] The difference between this embodiment and Embodiment 3 is that the structuring control agent is dimethyldiethoxysilane.

[0075] Example 5

[0076] The difference between this embodiment and Embodiment 4 is that the structuring control agent is hexamethyldisilazane.

[0077] Example 6

[0078] The difference between this embodiment and Embodiment 5 is that the vinyl molar fraction of the vinyl MQ silicone resin is 0.13%.

[0079] Example 7

[0080] The difference between this embodiment and Embodiment 5 is that the vinyl molar fraction of the vinyl MQ silicone resin is 0.15%.

[0081] Example 8

[0082] The difference between this embodiment and Embodiment 5 is that the vinyl molar fraction of the vinyl MQ silicone resin is 0.17%.

[0083] Example 9

[0084] The difference between this embodiment and Example 8 is that the modified methyl vinyl silicone resin is prepared according to the method of Preparation Example 2.

[0085] Example 10

[0086] The difference between this embodiment and Example 8 is that the modified methyl vinyl silicone resin is prepared according to the method of Preparation Example 3.

[0087] Example 11

[0088] The difference between this embodiment and Example 8 is that the modified methyl vinyl silicone resin is prepared according to the method of Preparation Example 4.

[0089] Comparative Example

[0090] Comparative Example 1

[0091] In this comparative example, the molecular weight of the methyl vinyl silicone rubber is 550,000, and the vinyl content is 0.17 mol%. The structuring control agent is hydroxyl silicone oil, the filler is nano silica, and the vulcanizing agent is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0092] This comparative example provides a compounded silicone rubber comprising the following components in parts by weight: 60g of methyl vinyl silicone rubber, 3g of structure control agent, 3.5g of filler, and 2.0g of vulcanizing agent.

[0093] This comparative example provides a method for preparing high-temperature resistant compounded silicone rubber, including the following steps:

[0094] (1) Place methyl vinyl silicone rubber and structure control agent in a two-roll mill, mix at 40°C for 4 hours, raise the temperature to 120°C and continue mixing for 2 hours, lower the temperature to 40°C, add filler and vulcanizing agent, continue plasticizing for 2 hours, and after mixing, pass through thin sheets to form compound rubber.

[0095] (2) Add the compounded rubber to the flat vulcanizing machine, set the pressure to 25MPa and the temperature to 160℃, and then vulcanize it. After vulcanizing for 10 minutes, take it out and wait for it to cool naturally to obtain the compounded silicone rubber.

[0096] Comparative Example 2

[0097] The difference between this comparative example and Example 1 is that the modified methyl vinyl silicone rubber was replaced with the same mass of methyl vinyl silicone rubber as in Comparative Example 1.

[0098] Comparative Example 3

[0099] The difference between this comparative example and Example 1 is that the same mass of methylphenyl silicone rubber was replaced with the same mass of methyl vinyl silicone rubber as in Comparative Example 1.

[0100] Comparative Example 4

[0101] The difference between this comparative example and Example 1 is that the same mass of vinyl MQ silicone resin was replaced with the same methyl vinyl silicone rubber as in Comparative Example 1.

[0102] Comparative Example 5

[0103] The difference between this comparative example and Example 1 is that the lignin-modified nano-silica is replaced with unmodified nano-silica.

[0104] Performance testing methods

[0105] Referring to the description in GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber", the compounded silicone rubber prepared in each example and comparative example was cut into test samples that met the test specifications. After being treated in room temperature and 350℃ oven for 6 hours, the tensile strength was tested respectively. The tensile rate was set to 500 mm / min during the test. The test results are shown in Table 2.

[0106] In addition to testing tensile strength, the weight loss rate of the specimen after high-temperature treatment was also weighed and calculated, and the results are shown in Table 2.

[0107] Table 2 Detection Results

[0108]

[0109]

[0110] Combining Examples 1-3 and Comparative Example 1 with Table 2, it can be seen that the silicone rubber compounds of Examples 1-3 still possess high tensile strength and minimal weight loss after high-temperature treatment. This is because the synergistic effect of rigid groups, cross-linked network structure, and lignin nano-modified silica in Examples 1-3 effectively weakens the main chain degradation reaction of the silicone rubber compounded under high temperature, resulting in better thermal stability and maintaining good mechanical properties after high-temperature treatment. Comparative Example 1, however, lacks this synergistic effect, and therefore loses most of its tensile strength and experiences significant weight loss after high-temperature treatment.

[0111] As can be seen from Example 1 and Comparative Examples 2-5 and Table 2, the silicone rubber compound of Example 1 still has high tensile strength and less weight loss after high temperature treatment. This is because the rigid groups of Comparative Examples 2-3 are missing, the cross-linking network structure of Comparative Example 4 cannot be fully improved, and the filler of Comparative Example 5 cannot cooperate with the rigid groups to hinder the movement of the silicone rubber molecular chains. As a result, the silicone rubber compound of Comparative Examples 2-5 generally showed more severe thermal degradation and lost more mechanical properties.

[0112] As can be seen from Examples 3-5 and Table 2, the compounded silicone rubber of Example 5 still has high tensile strength and less weight loss after high-temperature treatment. This is because the rigid hexamethyldisilazane in Example 5 can produce a good synergistic effect with the rigid groups in the modified methyl vinyl silicone rubber, methyl phenyl silicone rubber and other components, thereby effectively improving the high-temperature resistance of the compounded silicone rubber and enabling the compounded silicone rubber to maintain good mechanical properties after high-temperature treatment.

[0113] As can be seen from Examples 5-8 and Table 2, the compounded silicone rubbers of Examples 6-8 still have high tensile strength and low weight loss after high-temperature treatment. This is because when the vinyl molar fraction of vinyl MQ silicone resin is 0.13-0.17%, it can fully promote the cross-linking of vinyl MQ silicone resin and silicone rubber molecules, effectively improve the high-temperature resistance of the compounded silicone rubber, and enable the compounded silicone rubber to maintain good mechanical properties after high-temperature treatment.

[0114] As can be seen from Examples 8-11 and Table 2, the compounded silicone rubber can still maintain good heat resistance after the composition of the polyimide groups is changed.

[0115] The above embodiments are merely explanations of this application and are not intended to limit it. After reading this specification, those skilled in the art can make modifications to the embodiments of this application without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of this application.

Claims

1. A high-temperature resistant compounded silicone rubber, characterized in that, The product comprises the following components in parts by weight: 40-45 parts modified methyl vinyl silicone rubber, 10-15 parts methyl phenyl silicone rubber, 10-15 parts vinyl MQ silicone resin, 3-5 parts structure control agent, 3.5-4.5 parts filler, and 2.0-2.5 parts vulcanizing agent; the modified methyl vinyl silicone rubber contains polyimide groups and lignin groups; the filler includes lignin-modified nano silica. The modified methyl vinyl silicone rubber is prepared according to the following method: (1) Mix methyl vinyl silicone rubber with toluene until uniform, add dimethyl chlorosilane to the mixture, stir and heat under nitrogen protection, add platinum catalyst, continue to keep the reaction at the temperature, then cool down and discharge the material. After purification and post-treatment, silicone rubber intermediate material is obtained. (2) Add the silicone rubber intermediate to tetrahydrofuran and stir to dissolve. Then add hydroxyethylated lignin, hydroxyl-containing polyimide and acid binder. Stir and heat at a constant temperature under nitrogen protection. After the reaction is completed, discharge the material and then wash and vacuum dry to obtain modified methyl vinyl silicone rubber. The lignin-modified nano-silica was prepared according to the following method: Sodium silicate, alkali lignin, and deionized water were mixed and stirred to dissolve. Then, deionized water, ethanol, and polyethylene glycol were added and stirred. Sulfuric acid was added for acidification, and the mixture was stirred to obtain a nano-silica suspension. The nano-silica suspension was ultrasonically treated and preheated. Sulfuric acid was added again for acidification, followed by static treatment. The solid product was collected by vacuum filtration, and after acid washing and drying, lignin-modified nano-silica was obtained.

2. The high-temperature resistant compounded silicone rubber according to claim 1, characterized in that, The structuring control agent is one of hydroxyl silicone oil, dimethyldiethoxysilane, or hexamethyldisilazane.

3. The high-temperature resistant compounded silicone rubber according to claim 1, characterized in that, The vinyl MQ silicone resin has a vinyl molar fraction of 0.13-0.17%.

4. The high-temperature resistant compounded silicone rubber according to claim 1, characterized in that, The hydroxyl-containing polyimide is prepared according to the following method: After mixing diamine monomer, dianhydride monomer and m-cresol, isoquinoline was added dropwise to the mixture, and then the mixture was heated under nitrogen protection to obtain a reaction solution. The reaction solution was cooled, and excess ethanol was added to precipitate the mixture. After vacuum filtration and washing, hydroxyl-containing polyimide was obtained; the diamine monomer contained phenolic hydroxyl groups.

5. The high-temperature resistant compounded silicone rubber according to claim 4, characterized in that, The diamine monomer is selected from 3,3'-dihydroxybenzidine or 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane.

6. The high-temperature resistant compounded silicone rubber according to claim 4, characterized in that, The dianhydride monomer is selected from 4,4'-(4,4'-isopropyldiphenoxy) phthalic anhydride, 4,4'-(hexafluoroisopropene) phthalic anhydride, or 4,4'-oxophthalic anhydride.

7. The high-temperature resistant compounded silicone rubber according to claim 1, characterized in that, The hydroxyethylated lignin was prepared according to the following method: Enzymatically hydrolyzed lignin, ethylene carbonate, and tetrabutylammonium iodide were mixed and stirred to obtain a reaction mixture. Ethanol was added to the reaction mixture to obtain a diluted mixture. The diluted mixture was added to hydrochloric acid, and then the reaction was carried out under freezing conditions. After the reaction was completed, the mixture was filtered and the residue was collected. The residue was washed and freeze-dried to obtain hydroxyethylated lignin.

8. The method for preparing high-temperature resistant compounded silicone rubber according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Modified methyl vinyl silicone rubber, methyl phenyl silicone rubber, structural control agent and vinyl MQ silicone resin are placed in a two-roll mill for mixing. Fillers and vulcanizing agents are added during the mixing process. After mixing, the mixture is sheeted out to form a compound. (2) Add the compounded rubber to a flat vulcanizing machine for vulcanization, and then wait for it to cool naturally to obtain high temperature resistant compounded silicone rubber.

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