Pressure-resistant and tear-resistant silicone rubber and method for producing the same

Abstract

The application discloses a pressure-resistant and tear-resistant silicone rubber and a preparation method thereof, and belongs to the technical field of high polymer composite materials. The application first introduces a vinyl group through a silanization reaction and a Suzuki coupling reaction of 3-bromo-5-hydroxybenzoic acid methyl ester, and then reacts with NH2-PPTA to prepare a modified rigid rod-shaped reinforcing agent. The reinforcing agent is blended and vulcanized with methyl vinyl silicone rubber and phenyl silicone rubber to prepare a silicone rubber composite material. The application grafts trimethylsiloxy and a vinyl group on the surface of NH2-PPTA, improves the interfacial compatibility of the rigid rod-shaped molecule and the silicone rubber matrix, and constructs a rigid reinforcing network through a covalent bond, which synergistically acts with the phenyl silicone rubber, and significantly improves the tear resistance and compression permanent deformation resistance of the material. Experiments show that the tear strength of the silicone rubber is more than 81.5 kN / m, the compression permanent deformation is less than 7.5%, the comprehensive performance is excellent, and the silicone rubber is suitable for fields such as dynamic sealing elements and high-load buffer elements.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and more specifically, to a silicone rubber with excellent tear resistance and compression set resistance, and a method for preparing the same. Background Technology

[0002] Silicone rubber, due to its Si-O-Si main chain structure, possesses excellent resistance to high and low temperatures, aging resistance, electrical insulation, and biocompatibility, and is widely used in aerospace, electronics, automotive manufacturing, and medical devices. However, the weak intermolecular forces in silicone rubber result in poor mechanical properties, particularly tear strength and compression set resistance, which significantly limits its service life and reliability under harsh conditions such as dynamic sealing and high-load cushioning.

[0003] To improve the mechanical properties of silicone rubber, existing technologies mainly employ nanofillers (such as silica) for reinforcement and modify the surface of the fillers using silane coupling agents to improve their dispersibility and interfacial bonding in the matrix. For example, Chinese patent CN113527888B discloses a method for constructing a giant rigid crosslinked structure centered on silica by introducing epoxidized silicone rubber and utilizing its epoxy groups to react with the hydroxyl groups on the surface of silica, significantly improving tear strength. Another strategy is to introduce rigid polymer chains, such as Chinese patent CN116355221B, which improves the thermal stability and mechanical strength of the material by copolymerizing rigid structures such as bisphenol fluorene into the polysiloxane backbone.

[0004] However, the existing technology still has the following shortcomings: (1) Traditional rigid fillers (such as carbon fiber and cellulose) have poor interfacial compatibility with silicone rubber matrix, and are prone to agglomeration to form stress concentration points, which leads to limited reinforcement effect and even sacrifice of the elasticity and toughness of the material; (2) Simple chemical cross-linking network reinforcement often increases the rigidity of the material while improving the strength, which leads to a decrease in its resistance to permanent compression deformation, that is, the material is difficult to recover its original shape after long-term pressure; (3) There is a lack of effective technical solutions that can simultaneously and synergistically improve the tear resistance and compression resistance of the material.

[0005] In recent years, rigid rod-shaped polymers have been considered ideal reinforcing agents for flexible chain polymers due to their unique molecular morphology, excellent mechanical properties, and thermal stability. When rigid rod-shaped polymers are uniformly dispersed in a matrix, the resulting molecular composites exhibit significantly improved mechanical properties, low density, good processability, and broad application prospects. However, due to their low mixing entropy and positive mixing enthalpy, rigid polymers are prone to incompatibility or phase separation when blended with flexible polymers. To address this, researchers have introduced ionic interactions, acid-base interactions, and hydrogen bonding interactions to reduce the aggregation of rigid polymers.

[0006] Therefore, developing a silicone rubber composite material that combines high tear resistance and high compression resistance, good compatibility of its components, and excellent comprehensive mechanical properties is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] To overcome the above deficiencies, the present invention provides a silicone rubber with both excellent tear resistance and compression set resistance, and a method for preparing the same.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A pressure-resistant and tear-resistant silicone rubber, characterized in that it is prepared from raw materials comprising the following components in parts by weight: 100 parts of methyl vinyl silicone rubber; 20-30 parts of phenyl silicone rubber; 5-25 parts of modified rigid rod-shaped reinforcing agent; 10-30 parts of reinforcing agent; Vulcanizing agent 0.5-3 parts; 3-4 parts lubricant; 1-5 parts of alkenyl crosslinking agent; Anti-aging agent 1-5 parts; The modified rigid rod-shaped reinforcing agent is prepared by grafting functional groups containing siloxane and alkenyl groups onto the surface of aminated rigid rod-shaped polymer poly(2-aminoterephthalamide p-phenylenediamine) (NH2-PPTA).

[0009] Furthermore, the preparation process of the modified rigid rod-shaped reinforcing agent includes the following steps: Step S1: Methyl 3-bromo-5-hydroxybenzoate and pyridine are dissolved in an organic solvent and reacted with trimethylchlorosilane at 0-35°C. After hydrolysis, acidification, extraction and recrystallization, 3-(trimethylsiloxy)-5-bromobenzoic acid is obtained. Step S2: The 3-(trimethylsiloxy)-5-bromobenzoic acid obtained in step S1 is subjected to a Suzuki coupling reaction with vinylboronic acid pinacol ester in the presence of a catalyst and a base to obtain 3-(trimethylsiloxy)-5-vinylbenzoic acid. Step S3: Dissolve the 3-(trimethylsiloxy)-5-vinylbenzoic acid obtained in step S2 in an organic solvent, react it with NH2-PPTA in the presence of a condensing agent and a catalyst, and after precipitation, washing and drying, obtain the modified rigid rod-shaped reinforcing agent, denoted as VT-PPTA.

[0010] Further, the specific preparation process of step S1 is as follows: Under ice bath and nitrogen protection, methyl 3-bromo-5-hydroxybenzoate and pyridine are dissolved in anhydrous toluene, and trimethylchlorosilane is slowly added dropwise, controlling the reaction temperature at 20-35℃, and the reaction is carried out for 4-8 hours. After the reaction is completed, the pyridine salt is removed by filtration, and the filtrate is concentrated under reduced pressure to obtain the crude product. The crude product is dissolved in methanol, hydrolyzed with sodium hydroxide aqueous solution, acidified with hydrochloric acid, extracted with dichloromethane, and the organic phase is dried over anhydrous sodium sulfate, concentrated under reduced pressure, and finally recrystallized from ethanol to obtain 3-(trimethylsiloxy)-5-bromobenzoic acid.

[0011] Further, the specific preparation process of step S2 is as follows: 3-(trimethylsiloxy)-5-bromobenzoic acid, pinacol vinylborate obtained in step S1, the catalyst [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride (Pd(dppf)Cl2), and the base N,N-diisopropylethylamine (DIPEA) are added to toluene, and a Suzuki coupling reaction is carried out at 80-90℃ under nitrogen protection for 5-8 hours. After the reaction, the solvent is removed by concentration under reduced pressure, and the residue is purified by column chromatography or recrystallization to obtain 3-(trimethylsiloxy)-5-vinylbenzoic acid.

[0012] Further, the specific preparation process of step S3 is as follows: 3-(trimethylsiloxy)-5-vinylbenzoic acid obtained in step S2 is dissolved in N,N-dimethylformamide (DMF), 4-dimethylaminopyridine (DMAP) catalyst and dicyclohexylcarbodiimide (DCC) condensing agent are added, and then NH2-PPTA is added. The mixture is stirred and reacted at 40-60℃ for 24-48 hours. After the reaction is completed, the reaction solution is slowly added dropwise to a large amount of ethanol to precipitate the precipitate. The precipitate is filtered and repeatedly washed with ethanol to remove unreacted small molecules and condensing agent byproducts. Finally, the product is vacuum dried at 50-60℃ to constant weight to obtain the modified rigid rod-shaped reinforcing agent.

[0013] Furthermore, in step S3, NH2-PPTA is an aminated rigid rod-shaped polymer, prepared according to the method disclosed in the prior art (CN118290736A), and the specific steps are as follows: Step 1: Synthesis of the nitro-containing precursor NO2-PPTA: Under nitrogen protection, 2-nitro-1,4-phenylenediamine and lithium chloride (LiCl) were dissolved in a mixed solvent of anhydrous N,N-dimethylacetamide (DMAc) and pyridine, and cooled to 0°C. Terephthaloyl chloride (TPC) powder was added directly under magnetic stirring, and the reaction was allowed to proceed for approximately 10 minutes until gel formation. The mixture was then heated to 80°C and the reaction continued for 1 hour to complete the polycondensation. The reaction solution was poured into deionized water, and the precipitate was separated by filtration, washed twice with deionized water and ethanol, and finally dried at 80°C to obtain a yellow powdery NO2-PPTA.

[0014] Step 2: Nitro Reduction to Prepare NH2-PPTA: The NO2-PPTA obtained in Step 1 was dissolved in DMAc, and 10% Pd / C catalyst and LiCl were added. The mixture was heated to 108℃ under a hydrogen atmosphere for 12-24 hours. After the reaction was completed, the mixture was cooled to room temperature, and the Pd / C powder was removed by vacuum filtration. The polymer solution was poured into deionized water, and the precipitate was separated by filtration. It was first washed with deionized water, then thoroughly washed with ethanol, and finally vacuum dried at 80℃ overnight to obtain brown powdered NH2-PPTA.

[0015] Preferably, the methyl vinyl silicone rubber has a vinyl molar fraction of 0.13-0.25%; the phenyl silicone rubber has a phenyl content of 2.5-10% and a vinyl content of 0.10-0.25%.

[0016] Preferably, the reinforcing agent is fumed silica with a fineness of not less than 1000 mesh.

[0017] Preferably, the vulcanizing agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (bis(2,5-dimethyl-2,5-di(tert-butylperoxy)hexane), the alkenyl crosslinking agent is a mixture of triallyl isocyanate and trimethallyl isocyanate in a mass ratio of 3:1, the antioxidant is N-phenyl-2-naphthylamine, and the lubricant is a mixture of calcium stearate and microcrystalline wax in a mass ratio of 2:1.

[0018] The present invention also provides a method for preparing pressure-resistant and tear-resistant silicone rubber according to any of the foregoing technical solutions, comprising the following steps: Step A: Add methyl vinyl silicone rubber and phenyl silicone rubber to a two-roll mill and mix at 40-60℃ for 2-5 minutes. Then add modified rigid rod reinforcing agent, reinforcing agent, lubricant and antioxidant, and mix at 30-40℃ for 5-10 minutes. Then add vulcanizing agent and alkenyl crosslinking agent, and continue mixing for 3-5 minutes to obtain compound rubber. Step B: Place the compounded rubber sheet obtained in Step A into a flat vulcanizing machine for vulcanization. The vulcanization temperature is 160-175℃ and the vulcanization time is 10-15 minutes.

[0019] Compared with the prior art, the present invention has the following advantages: 1. Excellent interfacial compatibility and dispersibility: This invention grafts trimethylsiloxy groups onto the surface of NH2-PPTA, making its surface functional groups similar to the main chain structure of silicone rubber. Based on the principle of similar compatibility, this greatly improves the interfacial compatibility between rigid rod-shaped molecules and the methyl vinyl silicone rubber / phenyl silicone rubber matrix, achieving nanoscale uniform dispersion in the matrix and avoiding phase separation and stress defects caused by interfacial incompatibility.

[0020] 2. Construction of a rigid, chemically bonded network: The vinyl groups grafted onto the surface of NH2-PPTA can undergo co-crosslinking reactions with the alkenyl crosslinking agents in the silicone rubber matrix under the initiation of a peroxide vulcanizing agent, forming chemical bonds. This makes the high-modulus, high-strength rigid rod-shaped NH2-PPTA molecules no longer simple physical fillers, but rather firmly embedded through covalent bonds, becoming rigid crosslinking points in the three-dimensional network structure of silicone rubber.

[0021] 3. Synergistic Enhancement of Tear Resistance: When the material is subjected to tearing stress, on the one hand, the rigid NH2-PPTA skeleton acts as a "molecular-level reinforcing bar," bearing and transferring the stress itself; on the other hand, the strong interfacial chemical bonds ensure efficient stress transfer from the flexible silicone rubber matrix to the rigid skeleton, avoiding interfacial debonding. Simultaneously, the uniformly dispersed rigid skeleton effectively deflects and blunts crack tips, forcing the crack propagation path to be tortuous, thereby consuming a large amount of tearing energy and significantly improving the material's tear strength.

[0022] 4. Significantly Improved Compression Set Resistance: The uniformly dispersed and chemically cross-linked rigid NH2-PPTA network acts as a "skeletal support" in the silicone rubber matrix, effectively limiting the slippage and rearrangement of silicone rubber molecular chains under long-term pressure, and improving the stability of the cross-linked network. After the external force is removed, this stable network structure gives the material a stronger rebound driving force, enabling it to recover its original shape more quickly and completely, thereby significantly reducing compression set and improving the material's pressure resistance and dimensional stability. The compression set of Comparative Example 5 (without phenyl silicone rubber) was 13.8%, Comparative Example 3 (5 parts phenyl silicone rubber) improved to 10.1%, while Example 2 (20 parts phenyl silicone rubber) further reduced it to 7.3%, and Example 4 (25 parts phenyl silicone rubber) was 7.5%. This indicates that the appropriate combination of phenyl silicone rubber and methyl vinyl silicone rubber helps to further improve the resistance to compression set. The rigid structural units of phenyl silicone rubber help to stabilize the crosslinking network, restrict the slippage and rearrangement of molecular chains under long-term pressure, and form a synergistic effect with the rigid network of VT-PPTA, jointly improving the compressive strength and dimensional stability of the material. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the synthetic route for the modified rigid rod-shaped reinforcing agent (VT-PPTA) in this invention. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] Description of the main raw materials used in the examples: The methyl vinyl silicone rubber was selected from type 110-2 raw rubber and was provided by Anhui Mingyi Silicon Industry Co., Ltd. Phenyl silicone rubber (5% phenyl content, 0.18% vinyl content), commercially available; The reinforcing agent was selected from 1250 mesh fumed silica, provided by Guangdong Hengtian New Materials Technology Co., Ltd. The alkenyl crosslinking agent is composed of triallyl isocyanate and trimethylallyl isocyanate in a mass ratio of 3:1, both of which are industrial-grade raw materials. The lubricant is a mixture of NJ-026A type calcium stearate and 80# microcrystalline wax in a mass ratio of 2:1, and is provided by Dongguan Nuojia Plastics Co., Ltd. and Jining Tangyi Chemical Co., Ltd., respectively. All other reagents were commercially available analytical grade or chemically pure.

[0026] Preparation Example 1: Preparation of Aminated Rigid Rod-shaped Polymer NH2-PPTA Step 1: Synthesis of the nitro-containing precursor NO2-PPTA. Under nitrogen protection, 36.75 g (0.24 mol) of 2-nitro-1,4-phenylenediamine and 12 g of LiCl were dissolved in a mixed solvent of 600 mL DMAc and 60 mL pyridine. The solution was cooled to 0°C, and after purging with nitrogen for half an hour, 52.79 g (0.26 mol) of TPC powder was directly added under magnetic stirring. Stirring was continued for about 10 minutes until gelation occurred, and then the mixture was heated to 80°C and reacted for 1 hour to complete the polycondensation. The reaction solution was poured into deionized water, and the precipitate was separated by filtration, washed twice with deionized water and ethanol, and finally dried at 80°C to obtain a yellow powder NO2-PPTA with a yield of 92.5%.

[0027] Step 2: Nitro reduction to prepare NH2-PPTA. 20 g NO2-PPTA, 0.2 g 10% Pd / C catalyst, and 10 g LiCl were dissolved in 500 mL DMAc and reacted at 108 °C for 24 hours under a hydrogen atmosphere. After the reaction, the mixture was cooled to room temperature, and the Pd / C powder was removed by vacuum filtration. The polymer solution was poured into deionized water, and the precipitate was separated by filtration. The precipitate was washed first with deionized water, then thoroughly washed with ethanol, and finally dried under vacuum at 80 °C overnight to obtain brown powdered NH2-PPTA with a yield of 88.3%.

[0028] Preparation Example 2: Preparation of modified rigid rod-shaped reinforcing agent VT-PPTA (the synthetic route of VT-PPTA is as follows) Figure 1 (As shown) Step S1: Synthesis of 3-(trimethylsiloxy)-5-bromobenzoic acid. Under ice bath conditions, 5 mmol of methyl 3-bromo-5-hydroxybenzoate and 6 mmol of pyridine were added to a three-necked flask containing 20 mL of anhydrous toluene, and the mixture was stirred until dissolved. 2.5 mmol of trimethylchlorosilane was slowly added dropwise, and the reaction was carried out at 25 °C for 6 hours. After the reaction was complete, the mixture was filtered, and the filtrate was concentrated under reduced pressure. The concentrate was dissolved in 30 mL of methanol, and 20 mL of 10% NaOH aqueous solution was added. The mixture was stirred at room temperature for 2 hours. The pH was adjusted to 2-3 with dilute hydrochloric acid, and the mixture was extracted with dichloromethane (30 mL × 3). The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure. The residue was recrystallized from ethanol to give 3-(trimethylsiloxy)-5-bromobenzoic acid, with a yield of 86.7%.

[0029] Step S2: Synthesis of 3-(trimethylsiloxy)-5-vinylbenzoic acid. 2 mmol of 3-(trimethylsiloxy)-5-bromobenzoic acid, 2.4 mmol of pinacol vinylborate, 0.02 mmol of Pd(dppf)Cl2, and 4 mmol of DIPEA were added to 50 mL of toluene. The mixture was heated to 85 °C for 6 hours under nitrogen protection. After the reaction was complete, the mixture was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 5 / 1) to give 3-(trimethylsiloxy)-5-vinylbenzoic acid in 82.1% yield.

[0030] Step S3: Synthesis of VT-PPTA. 1 g of NH2-PPTA prepared in Preparation Example 1 was dissolved in 50 mL of DMF. 2 g of 3-(trimethylsiloxy)-5-vinylbenzoic acid prepared in Step S2, 0.1 g of DMAP, and 1 g of DCC were added. The mixture was stirred at 50 °C for 36 hours. After the reaction was complete, the reaction solution was slowly added dropwise to 500 mL of anhydrous ethanol, causing a precipitate to form. The precipitate was filtered, washed three times with anhydrous ethanol, and then dried under vacuum at 50 °C to constant weight to obtain the modified rigid rod-shaped reinforcing agent VT-PPTA, with a yield of 79.6%.

[0031] Example 1 Prepare the raw materials according to the following weight ratio: 100 parts methyl vinyl silicone rubber, 20 parts phenyl silicone rubber, 10 parts VT-PPTA, 20 parts fumed silica, 2 parts calcium stearate, 1.5 parts microcrystalline wax, 2 parts N-phenyl-2-naphthylamine, 1.5 parts divinyl chloride, and 3 parts alkenyl crosslinking agent (TAIC:TMAIC=3:1).

[0032] Preparation method: Methyl vinyl silicone rubber and phenyl silicone rubber were added to a two-roll mill and mixed at 50°C for 3 min. Then, VT-PPTA, fumed silica, calcium stearate, microcrystalline wax, and N-phenyl-2-naphthylamine were added and mixed at 35°C for 8 min. Next, bis(2,5-dimethyl)sulfurizing agent and alkenyl crosslinking agent were added, and mixing continued for 4 min to obtain the compound. The compounded rubber sheet was placed in a flat vulcanizing machine and vulcanized at 170°C for 12 min to obtain a pressure-resistant and tear-resistant silicone rubber composite material.

[0033] Example 2 The formulation and preparation steps are basically the same as in Example 1, except that the amount of VT-PPTA is adjusted to 15 parts.

[0034] Example 3 The formulation and preparation steps are basically the same as in Example 1, except that the amount of VT-PPTA is adjusted to 20 parts.

[0035] Example 4 The formulation and preparation steps are basically the same as in Example 2, except that the amount of phenyl silicone rubber is adjusted to 25 parts.

[0036] Example 5 The formulation and preparation steps are basically the same as in Example 2, except that the amount of phenyl silicone rubber is adjusted to 30 parts.

[0037] Comparative Example 1 Compared with Example 2, the difference is that VT-PPTA is not added, and the amount of fumed silica is adjusted to 25 parts to ensure the basic reinforcement effect. The remaining components and preparation steps are exactly the same as in Example 2.

[0038] Comparative Example 2 Compared to Example 2, the difference is that 15 parts of unmodified NH2-PPTA (obtained in Preparation Example 1) were added instead of VT-PPTA. The remaining components and preparation steps are exactly the same as in Example 2.

[0039] Comparative Example 3 Compared to Example 2, the difference lies in adjusting the amount of phenyl silicone rubber to 5 parts (methyl vinyl silicone rubber: phenyl silicone rubber = 100: 5). The remaining components and preparation steps are exactly the same as in Example 2.

[0040] Comparative Example 4 Compared to Example 2, the difference lies in adjusting the amount of phenyl silicone rubber to 40 parts (methyl vinyl silicone rubber: phenyl silicone rubber = 100: 40). The remaining components and preparation steps are exactly the same as in Example 2.

[0041] Comparative Example 5 Compared to Example 2, the difference is that phenyl silicone rubber is not added, while the amount of methyl vinyl silicone rubber remains 100 parts. The remaining components and preparation steps are exactly the same as in Example 2.

[0042] Performance testing: The performance of the silicone rubber composite materials prepared in Examples 1-5 and Comparative Examples 1-5 was tested using the following methods: Tensile properties: Tested on a universal testing machine according to GB / T 528-2009 standard, with a tensile speed of 500 mm / min.

[0043] Tear strength: Tested using right-angled specimens in accordance with GB / T 529-2008 standard.

[0044] Compression set: Tested according to GB / T 7759.1-2015 standard, at 150℃ for 24 hours and with a compression rate of 25%.

[0045] Hardness: Tested using a Shore A hardness tester according to GB / T 531.1-2008 standard.

[0046] The test results are listed in Table 1.

[0047]

[0048] Discussion of Results: As can be seen from the results in Table 1, the silicone rubber composite materials prepared in Examples 1-5 of the present invention exhibit significant advantages in all aspects of performance. The specific analysis is as follows: Comparing Examples 1-3 with Comparative Examples 1-2, it can be seen that the introduction of VT-PPTA has a decisive impact on the material properties. By grafting trimethylsiloxy and vinyl groups onto the surface of NH2-PPTA, the interfacial compatibility between the rigid rod-shaped molecules and the silicone rubber matrix is ​​greatly improved, achieving nanoscale uniform dispersion. Furthermore, the vinyl groups participate in the crosslinking reaction to form a chemically bonded rigid reinforcing network, thereby synergistically enhancing tear resistance and compression resistance.

[0049] Comparing Examples 2, 4, and 5 (with phenyl silicone rubber dosages of 20, 25, and 30 parts respectively, and VT-PPTA fixed at 15 parts) and Comparative Examples 3-5, it can be seen that the amount of phenyl silicone rubber has a significant impact: the introduction of an appropriate amount of phenyl silicone rubber (20-30 parts) can significantly improve the compression set properties of silicone rubber. This may be because the rigid structural units of phenyl silicone rubber help stabilize the crosslinking network and limit the slippage and rearrangement of molecular chains under long-term pressure. However, excessive phenyl silicone rubber dosage will lead to a decrease in crosslinking density, which is detrimental to mechanical properties.

[0050] Based on the above analysis, this invention successfully prepared a silicone rubber composite material with high tear resistance, low compression set, and excellent mechanical properties through the synergistic effect of VT-PPTA modified rigid rod-shaped reinforcing agent and an appropriate amount of phenyl silicone rubber. The preferred ratio is: 100 parts methyl vinyl silicone rubber, 20-25 parts phenyl silicone rubber, and 15-20 parts VT-PPTA. Within this range, a comprehensive performance of tear strength >79 kN / m, compression set <7.5%, and tensile strength >14.5 MPa can be obtained, significantly superior to existing technologies.

[0051] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pressure-resistant and tear-resistant silicone rubber, characterized in that, It is prepared from raw materials containing the following components in parts by weight: 100 parts of methyl vinyl silicone rubber; 20-30 parts of phenyl silicone rubber; 5-25 parts of modified rigid rod-shaped reinforcing agent; 10-30 parts of reinforcing agent; Vulcanizing agent 0.5-3 parts; 3-4 parts lubricant; 1-5 parts of alkenyl crosslinking agent; Anti-aging agent 1-5 parts; The modified rigid rod-shaped reinforcing agent is prepared by grafting functional groups containing siloxane and alkenyl groups onto the surface of aminated rigid rod-shaped polymer poly(2-aminoterephthalamide p-phenylenediamine) (NH2-PPTA).

2. The pressure-resistant and tear-resistant silicone rubber according to claim 1, characterized in that, The preparation process of the modified rigid rod-shaped reinforcing agent includes the following steps: Step S1: Methyl 3-bromo-5-hydroxybenzoate and pyridine are dissolved in an organic solvent and reacted with trimethylchlorosilane at 0-35°C. After hydrolysis, acidification, extraction and recrystallization, 3-(trimethylsiloxy)-5-bromobenzoic acid is obtained. Step S2: The 3-(trimethylsiloxy)-5-bromobenzoic acid obtained in step S1 is subjected to a Suzuki coupling reaction with vinylboronic acid pinacol ester in the presence of a catalyst and a base to obtain 3-(trimethylsiloxy)-5-vinylbenzoic acid. Step S3: Dissolve the 3-(trimethylsiloxy)-5-vinylbenzoic acid obtained in step S2 in an organic solvent, react it with NH2-PPTA in the presence of a condensing agent and a catalyst, and obtain the modified rigid rod-shaped reinforcing agent by precipitation, washing and drying.

3. The pressure-resistant and tear-resistant silicone rubber according to claim 2, characterized in that, The reaction temperature in step S1 is 20-35℃, and the reaction time is 4-8 hours; the organic solvent is toluene.

4. The pressure-resistant and tear-resistant silicone rubber according to claim 2, characterized in that, The catalyst in step S2 is [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride, the base is N,N-diisopropylethylamine, the reaction temperature is 80-90℃, and the reaction time is 5-8 hours.

5. The pressure-resistant and tear-resistant silicone rubber according to claim 2, characterized in that, The condensing agent in step S3 is dicyclohexylcarbodiimide, the catalyst is 4-dimethylaminopyridine, the reaction temperature is 40-60℃, and the reaction time is 24-48 hours.

6. The pressure-resistant and tear-resistant silicone rubber according to claim 1, characterized in that, The methyl vinyl silicone rubber has a vinyl molar fraction of 0.13-0.25%; the phenyl silicone rubber has a phenyl content of 2.5-10% and a vinyl content of 0.10-0.25%.

7. The pressure-resistant and tear-resistant silicone rubber according to claim 1, characterized in that, The reinforcing agent is fumed silica with a fineness of not less than 1000 mesh.

8. The pressure-resistant and tear-resistant silicone rubber according to claim 1, characterized in that, The vulcanizing agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (bis(2,5-dimethyl-2,5-di(tert-butylperoxy)hexane); the alkenyl crosslinking agent is a mixture of triallyl isocyanate and trimethallyl isocyanate in a mass ratio of 3:1; the antioxidant is N-phenyl-2-naphthylamine; and the lubricant is a mixture of calcium stearate and microcrystalline wax in a mass ratio of 2:

1.

9. A method for preparing pressure-resistant and tear-resistant silicone rubber according to any one of claims 1-8, characterized in that, Includes the following steps: Step A: Add methyl vinyl silicone rubber and phenyl silicone rubber to a two-roll mill and mix at 40-60℃ for 2-5 minutes. Then add modified rigid rod reinforcing agent, reinforcing agent, lubricant and antioxidant, and mix at 30-40℃ for 5-10 minutes. Then add vulcanizing agent and alkenyl crosslinking agent, and continue mixing for 3-5 minutes to obtain compound rubber. Step B: Place the compounded rubber sheet obtained in Step A into a flat vulcanizing machine for vulcanization. The vulcanization temperature is 160-175℃ and the vulcanization time is 10-15 minutes.

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