A tear-resistant silicone rubber and its preparation method

Abstract

This application discloses a tear-resistant silicone rubber and its preparation method. The tear-resistant silicone rubber comprises: 100 parts of raw silicone rubber, 2-6 parts of hydrogen-containing silicone oil A, 3-8 parts of an interface modifier, 0.05-0.3 parts of a platinum catalyst, 5-10 parts of carbon nanotubes, 5-10 parts of carbon black, and 1-2 parts of a structure control agent. The carbon nanotubes have a metal phthalocyanine complex attached to their surface. The interface modifier molecule contains Si-H and bipyridine groups. The interface modifier is prepared by hydrosilylation of hydrogen-containing silicone oil B with vinyl bipyridine. This application, by introducing a metal phthalocyanine complex onto the surface of carbon nanotubes and using hydrogen-containing silicone oil with bipyridine groups as an interface modifier, enables the silicone rubber to form a dynamic network during crosslinking, thereby achieving good interfacial bonding and significantly improving the tear resistance of the silicone rubber while maintaining excellent toughness.

Description

Technical Field

[0001] This application relates to the field of silicone rubber materials, and in particular to a tear-resistant silicone rubber and a method for preparing the same. Background Technology

[0002] Silicone rubber is widely used in aerospace, electronics, construction, and medical fields due to its excellent heat resistance, cold resistance, electrical insulation, and chemical stability. However, conventional silicone rubber has shortcomings in tear resistance, especially in applications requiring high strength and high toughness. To improve the tear resistance of silicone rubber, reinforcing fillers (such as carbon black, silica, and carbon nanotubes) are typically used for reinforcement.

[0003] Carbon nanotubes (CNTs) possess extremely high aspect ratios and mechanical properties, making them ideal reinforcements. However, the inert surface of CNTs makes them prone to aggregation in silicone rubber matrices, resulting in weak interfacial bonding and low reinforcement efficiency. Existing technologies mainly employ the following methods for modification: Firstly, acidification and oxidation treatments, while improving the dispersibility and compatibility of CNTs, often lead to structural damage, affecting their intrinsic properties and weakening their reinforcing effect. Secondly, after acidification or oxidation, covalent bonding between CNTs and silicone rubber can be achieved through silane coupling agents or free radical copolymerization. This method can also effectively improve tear resistance, but it easily leads to increased brittleness, decreased toughness, and deterioration of deformation resistance. Thirdly, using surfactants or polymers to physically adsorb and encapsulate CNTs, while preserving the CNT structure, results in weak interfacial interactions, making slippage easy under stress and hindering effective stress transfer, thus limiting the reinforcing effect. Summary of the Invention

[0004] This invention proposes a tear-resistant silicone rubber and its preparation method. By introducing a metal phthalocyanine complex on the surface of carbon nanotubes and using a hydrogen-containing silicone oil with bipyridine coordinating groups as an interface modifier, the silicone rubber can form a dynamic network during the crosslinking process, thereby achieving good interfacial bonding and significantly improving the tear resistance of the silicone rubber while maintaining excellent toughness.

[0005] In a first aspect, this application provides a tear-resistant silicone rubber comprising the following raw materials in parts by weight: 100 parts of raw silicone rubber, 2-6 parts of hydrogen-containing silicone oil A, 3-8 parts of interface modifier, 0.05-0.3 parts of platinum catalyst, 5-10 parts of carbon nanotubes, 5-10 parts of carbon black, and 1-2 parts of structure control agent; wherein the surface of the carbon nanotubes is coated with a metal phthalocyanine complex, and the interface modifier molecule has Si-H and bipyridine groups, and the interface modifier is prepared by hydrosilylation of hydrogen-containing silicone oil B and vinyl bipyridine.

[0006] In any of the above technical solutions, the hydrogen-containing silicone oil B is a hydrogen-containing silicone oil with Si-H at both end side chains, and the molar ratio of Si-H to vinyl bipyridine in the hydrogen-containing silicone oil B is 3-5:1-2.

[0007] In any of the above technical solutions, the reaction temperature of the hydrosilylation is 80℃~120℃, and the reaction time is 2~5 hours.

[0008] In any of the above technical solutions, the vinyl bipyridine is 4-vinyl-2,2'-bipyridine.

[0009] The adhesion of the metal phthalocyanine complex to the surface of carbon nanotubes is obtained by mixing and modifying carbon nanotubes with the metal phthalocyanine complex in a solvent, wherein the mass ratio of the carbon nanotubes to the metal phthalocyanine complex is 100:3 to 6.

[0010] In any of the above technical solutions, the metal phthalocyanine complex does not reach its maximum coordination number or has available empty orbitals / axial sites to facilitate coordination with bipyridine; preferably, the metal phthalocyanine complex is zinc phthalocyanine and / or copper phthalocyanine. It is worth noting that the coordination bonds formed by the bipyridine group used in this application have higher environmental stability than groups such as imidazole, which is beneficial for maintaining its long-term effectiveness.

[0011] This application utilizes the large conjugated aromatic structure of metal phthalocyanine complexes and the π-π stacking effect on the surface of CNTs to ensure their firm attachment to CNTs. This process maximizes the preservation of the CNTs' structure and mechanical properties, providing a foundation for efficient reinforcement. Subsequently, an interface modifier prepared by the addition reaction of hydrogen-containing silicone oil and vinyl bipyridine acts as a bridge in the system. During platinum-catalyzed vulcanization, the Si-H bonds on the modifier molecule participate in the formation of a covalent cross-linked network of silicone rubber, while the bipyridine groups on the molecule coordinate with the metal phthalocyanine central ions pre-attached to the CNTs surface. The strength of this coordination bond is higher than that of simple physical adsorption, enabling effective stress transfer from the rubber matrix to the high-strength CNTs, thereby significantly improving tear resistance. At the same time, it possesses a certain degree of dynamic reversibility; under external impact, the coordination bonds can undergo reversible breakage and recombination, absorbing and dispersing impact energy, avoiding the stress concentration and brittle fracture problems easily caused by traditional rigid covalent interfaces. Therefore, compared with the strong oxidation treatment that easily damages the CNT structure or the direct covalent grafting method that easily leads to brittle and hard interfaces in the prior art, this application achieves an excellent balance between strong interfacial bonding and good toughness through the synergy of π-π adsorption and coordination bonding, and realizes the simultaneous improvement of toughness and tear resistance.

[0012] In any of the above technical solutions, the raw silicone rubber is selected from one or more of methyl vinyl silicone rubber, methyl vinyl phenyl silicone rubber, and methyl vinyl trifluoropropyl silicone rubber; preferably methyl vinyl silicone rubber, with a vinyl content of 0.03 to 0.2 mol.

[0013] In any of the above technical solutions, the hydrogen-containing silicone oil A is an end-side hydrogen-containing silicone oil having at least 3 Si-H groups.

[0014] In any of the above technical solutions, the structure control agent is vinyl silicone oil.

[0015] In any of the above technical solutions, the tear-resistant silicone rubber comprises 5 to 8 parts of alkoxy-modified fluorosilicone rubber.

[0016] In any of the above technical solutions, the alkoxy-modified fluorosilicone rubber is prepared by hydrosilylation of hydrogen-containing alkoxysilane and methyl vinyltrifluoropropyl silicone rubber.

[0017] In any of the above technical solutions, the hydrogen-containing alkoxysilane is selected from one or more of triethoxysilane, trimethoxysilane, methyldimethoxysilane, and ethyldimethoxysilane.

[0018] In any of the above technical solutions, the mass ratio of the methyl vinyl trifluoropropyl silicone rubber to the hydrogen-containing alkoxysilane is 100:1 to 3.

[0019] In any of the above technical solutions, the number-average molecular weight of the methyl vinyl trifluoropropyl silicone rubber is 500,000 to 1,000,000.

[0020] While the bipyridine-metal phthalocyanine coordination system can effectively improve the tear resistance of silicone rubber, it is sensitive to polar media. Prolonged exposure to polar solvents such as water and ethanol can easily damage the coordination network, leading to a significant decrease in tear resistance. This invention effectively solves this problem by introducing a small amount of alkoxy-modified fluorosilicone rubber.

[0021] Specifically, a strong π-π interaction exists between carbon nanotubes with attached metal phthalocyanine complexes and carbon black. This interaction allows some carbon black to distribute around the carbon nanotubes after shear dispersion, forming a stable filler network. Simultaneously, the alkoxy groups in the alkoxy-modified fluorosilicone rubber can undergo hydrolysis in the processing or usage environment, generating active silanol groups in situ. These silanol groups can chemically react with the active groups on the carbon black surface, forming a stable grafted structure. Utilizing the low surface energy of the side groups of the fluorosilicone rubber backbone in the grafted structure, the penetration of polar solvents into the metal-nitrogen coordination bond region can be effectively blocked.

[0022] Through the synergistic effect of carbon black and alkoxy-modified fluorosilicone rubber, a localized hydrophobic layer is formed around the metal-nitrogen coordination bonds, significantly improving the environmental stability of the coordination network. It is important to note that existing technologies typically add large amounts of fluorosilicone rubber (>15 wt%) to improve the solvent resistance of silicone rubber materials. However, there are compatibility issues between fluorosilicone rubber and non-fluorosilicone rubber; excessive addition leads to a significant increase in system viscosity, a sharp decline in processability, and a high coefficient of thermal expansion, which easily causes rough and wrinkled surfaces on extruded products. This invention uses only a small amount (5-8 parts) of alkoxy-modified fluorosilicone rubber, avoiding compatibility issues while maintaining good processability. Furthermore, the additional chemical bonds formed between the fluorosilicone rubber phase and the carbon black reinforcing network further enhance the tear strength of the silicone rubber material, achieving the goal of maintaining excellent tear resistance over a long period in polar solvent environments.

[0023] Secondly, this application provides a method for preparing tear-resistant silicone rubber, comprising: According to the proportion of the tear-resistant silicone rubber described in any of the first aspects, the raw silicone rubber and fluorosilicone rubber are placed in a two-roll mill or internal mixer and mixed at 30-50°C until the mixture is stable around the rolls; then the structure control agent and carbon black are added, and the mixture is continued to be mixed for 10-20 minutes to obtain the masterbatch. Carbon nanotubes, an interface modifier, and hydrogen-containing silicone oil A are added to the masterbatch, and the mixture is further mixed at 30–50 °C for 5–15 minutes; then the mixture is allowed to stand at room temperature for 20–60 minutes to obtain a premixed rubber compound. The premixed rubber compound is cooled to ≤40℃, a platinum catalyst is added, and the mixture is rapidly passed through a thin tube 2-4 times at low temperature. After mixing evenly, the mixture is immediately sheeted to obtain a vulcanizable compound. The compound is then placed in a mold and placed in a flat vulcanizing machine. It is vulcanized for 5-30 minutes at a pressure of 1-15MPa and a temperature of 120-180℃ to complete the first stage of vulcanization. The vulcanized sample is then placed in a hot air circulating oven and baked at atmospheric pressure and 180-220℃ for 2-4 hours.

[0024] In the above preparation method, standing at room temperature for 20–60 minutes promotes coordination between bipyridine in the interface modifier molecule and the metal ions at the metal phthalocyanine center on the surface of the carbon nanotube. The second stage of vulcanization after the first stage is used to fully crosslink and remove low-molecular-weight byproducts (such as alcohols produced by alkoxy hydrolysis), thereby improving heat and solvent resistance.

[0025] In summary, this application has the following beneficial effects: The core of this application lies in utilizing the non-covalent modification of carbon nanotubes with metal phthalocyanines and their coordination bonding with silicone rubber containing bipyridine groups. This creates a strong interfacial bond between the carbon nanotubes and the silicone rubber matrix, significantly improving tear resistance while maintaining the material's toughness. Furthermore, by introducing alkoxy-modified fluorosilicone rubber, not only is the composite material's resistance to polar solvents effectively enhanced, but the hydrolysis-condensation reaction also strengthens the bond between the filler network and the rubber phase, thereby improving the overall structural stability and long-term reliability. Ultimately, the silicone rubber product solution of this application achieves the core material performance requirements of a tear strength greater than 35 kN / m and an elongation at break greater than 600%. Detailed Implementation

[0026] Preparation Example Preparation Example 1-1, Interface Modifier, was prepared according to the following steps: 500 g of end-side hydrogen-containing silicone oil (Ningbo Runhe RH-LHC-3, hydrogen content 0.8 wt%, total 4 mol Si-H) and 600 mL of anhydrous toluene were added to a reaction vessel under nitrogen protection. The temperature was raised to 110 °C, and 273 g (1.5 mol) of 4-vinyl-2,2'-bipyridine and 0.06 g of Karstedt catalyst (containing 2% Pt) were added. The reaction was stirred at 110 °C under a nitrogen atmosphere for 2 hours. After the reaction was completed, toluene was first recovered by atmospheric distillation, and then the temperature was raised to 130 °C and vacuum devolatilized at a vacuum degree of ≤5 mmHg for 2 hours. After cooling, the interface modifier was obtained.

[0027] Preparation Examples 1-2, interface modifiers, were prepared according to the following steps: 400 g of end-side hydrogen-containing silicone oil (Ningbo Runhe RH-LHC-3, hydrogen content 0.8 wt%, total 3.2 mol Si-H) and 500 mL of anhydrous toluene were added to a reaction vessel under nitrogen protection. The temperature was raised to 95 °C, and 182 g (1.5 mol) of 4-vinyl-2,2'-bipyridine and 0.05 g of Karstedt catalyst (containing 2% Pt) were added. The reaction was stirred at 95 °C under a nitrogen atmosphere for 5.0 hours. After the reaction was completed, toluene was first recovered by atmospheric distillation, and then the temperature was raised to 110 °C. Unreacted monomers were removed under reduced pressure at a vacuum degree of ≤10 mmHg for 1.5 hours. After cooling, the interface modifier was obtained.

[0028] Preparation Examples 1-3, interface modifiers, were prepared according to the following steps: 600 g of end-side hydrogen-containing silicone oil (Ningbo Runhe RH-LHC-3, hydrogen content 0.8 wt%, total 4.8 mol Si-H) and 700 mL of anhydrous toluene were added to a reaction vessel under nitrogen protection. The temperature was raised to 105 °C, and 365 g (2.0 mol) of 4-vinyl-2,2'-bipyridine and 0.08 g of Karstedt catalyst (containing 2% Pt) were added. The reaction was stirred at 105 °C under a nitrogen atmosphere for 3.5 hours. After the reaction was completed, toluene was first recovered by atmospheric distillation, and then the temperature was raised to 120 °C. Unreacted monomers were removed under reduced pressure at a vacuum degree of ≤5 mmHg for 1 hour. After cooling, the interface modifier was obtained.

[0029] Preparation Examples 1-4, interface modifiers, differ from Preparation Example 1-1 in that the end-side hydrogen-containing silicone oil (Ningbo Runhe RH-LHC-3, 0.8 wt% hydrogen content, 4 mol Si-H) is replaced with 11.4 mol of side-chain hydrogen-containing silicone oil (Ningbo Runhe RH-H536, 0.35 wt% hydrogen content, 4.0 mol Si-H).

[0030] Preparation Example 2-1: Modified carbon nanotubes were prepared according to the following procedure: 100 g of multi-walled carbon nanotubes (outer diameter 20–30 nm, length 10–30 μm, specific surface area ≥250 m²) were used. 2 Add 4.0 g of zinc phthalocyanine (average particle size 20 nm) to a three-necked flask, then add 1500 mL of N,N-dimethylformamide. Disperse ultrasonically at room temperature for 2 hours to form a uniform black suspension. Then add 4.0 g of zinc phthalocyanine (average particle size 20 nm), heat to 120 °C, and reflux mechanically under nitrogen protection for 6 hours to allow zinc phthalocyanine to adsorb onto the surface of multi-walled carbon nanotubes. After the reaction is complete, cool to room temperature, filter through a 0.22 μm polytetrafluoroethylene microporous membrane, and wash twice with 500 mL of hot N,N-dimethylformamide (60 °C) and twice with 300 mL of anhydrous ethanol to remove unadsorbed zinc phthalocyanine. Finally, dry the filter cake in an 80 °C vacuum drying oven for 12 hours to obtain modified carbon nanotubes.

[0031] Preparation Example 2-2: Modified carbon nanotubes were prepared according to the following procedure: 100g of multi-walled carbon nanotubes (outer diameter 10-20nm, length 5-15μm, specific surface area ≥300m²) were used. 2Add 3.2 g of copper phthalocyanine (average particle size 80 nm) to a reaction flask, and add 1200 mL of N,N-dimethylformamide. Disperse ultrasonically at room temperature for 2 hours to form a uniform black suspension. Add 3.2 g of copper phthalocyanine (average particle size 80 nm), heat to 110 °C, and reflux mechanically under nitrogen protection for 5 hours to allow copper phthalocyanine to adsorb onto the surface of multi-walled carbon nanotubes. After the reaction is complete, cool to room temperature, filter through a 0.22 μm polytetrafluoroethylene microporous membrane, and wash twice with hot N,N-dimethylformamide (60 °C) and twice with 300 mL of anhydrous ethanol to remove unadsorbed copper phthalocyanine. Finally, dry the filter cake in a vacuum drying oven at 60 °C for 16 hours to obtain modified carbon nanotubes.

[0032] Preparation Example 2-3: Modified carbon nanotubes were prepared according to the following procedure: 100 g of multi-walled carbon nanotubes (outer diameter 20–30 nm, length 10–30 μm, specific surface area ≥250 m²) were used. 2 5.5 g of zinc phthalocyanine (average particle size 20 nm) was added to a reaction flask, followed by 2000 mL of N,N-dimethylformamide. The mixture was ultrasonically dispersed at room temperature for 2 hours to form a uniform black suspension. Then, 5.5 g of zinc phthalocyanine (average particle size 20 nm) was added, and the mixture was heated to 120 °C and mechanically stirred under nitrogen protection for 6 hours to allow zinc phthalocyanine to adsorb onto the surface of multi-walled carbon nanotubes. After the reaction was complete, the mixture was cooled to room temperature and filtered through a 0.22 μm polytetrafluoroethylene microporous membrane. The filtered cake was then washed twice with 500 mL of hot N,N-dimethylformamide (60 °C) and twice with 300 mL of anhydrous ethanol to remove unadsorbed zinc phthalocyanine. Finally, the filter cake was dried in a vacuum drying oven at 80 °C for 12 hours to obtain modified carbon nanotubes.

[0033] Preparation Examples 2-4: Modified carbon nanotubes were prepared according to the following procedure: 100 g of multi-walled carbon nanotubes (outer diameter 20–30 nm, length 10–30 μm, specific surface area ≥250 m²) were used. 2 Add 1.5 L of deionized water to a mixture of sodium dodecyl sulfate (SLS) and 2.0 g of sodium dodecyl sulfate. Sonicate the mixture at room temperature for 3 hours to form a stable black suspension. Then, stir in a 60 °C water bath for 12 hours to allow the sodium dodecyl sulfate molecules to coat the carbon nanotube surface through hydrophobic interactions. After the reaction, centrifuge the suspension for 20 min, discard the supernatant, wash the precipitate five times with deionized water, and then vacuum dry at 80 °C for 12 hours to obtain the modified carbon nanotubes.

[0034] Preparation Examples 2-5: Modified carbon nanotubes were prepared according to the following procedure: 100 g of pre-acidified multi-walled carbon nanotubes (outer diameter 20–30 nm, length 10–30 μm, specific surface area ≥250 m²) were used. 2The modified carbon nanotubes (g / g) were placed in a 500 mL round-bottom flask, and 300 mL of anhydrous toluene and 5 mL of γ-methacryloyloxypropyltrimethoxysilane were added. Nitrogen gas was first purged for 10 minutes, followed by the addition of 0.5 mL of dibutyltin dilaurate. The mixture was heated to 110 °C and refluxed for 8 hours to allow the silane to hydrolyze and condense, grafting onto the hydroxyl groups on the surface of the multi-walled carbon nanotubes. After the reaction was complete, the mixture was cooled, filtered, and washed twice successively with 200 mL each of toluene and ethanol. The nanotubes were then dried under vacuum at 100 °C for 10 hours to obtain the modified carbon nanotubes.

[0035] Preparation Example 3-1, alkoxy-modified fluorosilicone resin, was prepared by the following method: 1000 g of methyl vinyl trifluoropropyl silicone rubber (Mn≈600,000, vinyl content 0.15 mol%) was added to a stainless steel reactor, and the reactor was evacuated and purged with nitrogen three times. The temperature was raised to 80 °C, and 20 g of a toluene solution of triethoxysilane and Karstedt catalyst (containing 2% Pt and 0.02 g of Karstedt catalyst) was added. The reaction was stirred at 80 °C under nitrogen protection for 4 hours. After the reaction was completed, the rubber compound was discharged while hot and placed on a two-roll mill. It was passed through a thin mill five times at a roll temperature of about 30 °C to obtain alkoxy-modified fluorosilicone rubber.

[0036] Preparation Example 3-2, alkoxy-modified fluorosilicone resin, was prepared by the following method: 1000 g of methyl vinyl trifluoropropyl silicone rubber (Mn≈600,000, vinyl content 0.15 mol%) was added to a stainless steel reactor, and the reactor was evacuated and purged with nitrogen three times. The temperature was raised to 70 °C, and 10 g of a toluene solution of methyl dimethoxysilane and Karstedt catalyst (containing 2% Pt and 0.015 g Karstedt catalyst) was added. The mixture was stirred and reacted at 70 °C under nitrogen protection for 5 hours. After the reaction was completed, the rubber compound was discharged while hot and placed on a two-roll mill. It was passed through a thin mill five times at a roll temperature of about 30 °C to obtain alkoxy-modified fluorosilicone rubber.

[0037] Preparation Example 3-3: Alkoxy-modified fluorosilicone resin was prepared according to the following method: 1000 g of methyl vinyl trifluoropropyl silicone rubber (Mn≈600,000, vinyl content 0.15 mol%) was added to a stainless steel reactor, and the reactor was evacuated and purged with nitrogen three times. The temperature was raised to 90 °C, and 30 g of a toluene solution of ethyl dimethoxysilane and Karstedt catalyst (containing 2% Pt and 0.025 g of Karstedt catalyst) was added. The reaction was stirred at 90 °C under nitrogen protection for 3.5 hours. After the reaction was completed, the rubber compound was discharged while hot and placed on a two-roll mill. It was passed through a thin mill five times at a roll temperature of about 30 °C to obtain alkoxy-modified fluorosilicone rubber.

[0038] Preparation Example 3-4, alkoxy-modified silicone resin, differs from Preparation Example 3-1 in that an equal amount of methyl vinyl trifluoropropyl silicone rubber (Mn≈600,000, vinyl content 0.15 mol%) is used instead of methyl vinyl trifluoropropyl silicone rubber (grade MY 3110-2, vinyl content 0.13-0.18 mol%).

[0039] Example Example 1: A tear-resistant silicone rubber was prepared according to the following method: 1000 g of methyl vinyl silicone rubber (Mingyi Silicon Industry MY 3110-2, vinyl content 0.13-0.18 mol%) and 65 g of alkoxy-modified fluorosilicone rubber (prepared in Preparation Example 3-1) were added to a two-roll mill. The roll temperature was controlled at 40 ℃. After the roll wrapping was stable, 15 g of α,ω-divinyl silicone oil (Gelest DMS-V52) and 75 g of carbon black (average particle size 20-25 nm) were added. The mixture was passed through a thin mill 5 times and then rolled in a triangular shape 3 times. After mixing for 15 minutes, a masterbatch was obtained. Subsequently, 70 g of modified carbon nanotubes (prepared in Preparation Example 2-1), 50 g of interface modifier (prepared in Preparation Example 1-1), and 40 g of hydrogen-containing silicone oil A (RH-LHC-3, hydrogen content 0.8 wt%) were added. The mixture was continued to be mixed for 10 minutes until homogeneous. The mixture was then allowed to stand at room temperature for 30 minutes to allow the bipyridine to fully coordinate with the metal phthalocyanine complex on the surface of the modified carbon nanotubes. Finally, add 2 g of Karstedt platinum catalyst (Pt content 2%), pass through a thin tube 3 times at 30℃, and quickly sheet the product. Place the rubber compound in a mold and vulcanize it at 160℃ and 10 MPa for 15 minutes. After demolding, vulcanize it in a 200℃ hot air oven for 3 hours to obtain tear-resistant silicone rubber products.

[0040] Example 2: A tear-resistant silicone rubber was prepared according to the following method: 1000 g of methyl vinyl silicone rubber (Wacker ELASTOSIL® R401 / 40, vinyl content 0.08 mol%) and 53 g of alkoxy-modified fluorosilicone rubber (prepared in Preparation Example 3-2) were added to a two-roll mill. The roll temperature was controlled at 40 °C. After the roll wrapping stabilized, 10 g of α,ω-divinyl silicone oil (Gelest DMS-V02) and 50 g of carbon black (average particle size 15-20 nm) were added. The mixture was passed through a thin mill 5 times, followed by three triangular wrapping cycles, and then mixed for 12 minutes to obtain the masterbatch. Subsequently, 50 g of modified carbon nanotubes (prepared in Preparation Example 2-2), 30 g of interface modifier (prepared in Preparation Example 1-2), and 20 g of hydrogen-containing silicone oil A (RH-H3, hydrogen content 0.28 wt%) were added, and the mixture was further mixed for 8 minutes until homogeneous. The mixture was then allowed to stand at room temperature for 20 minutes to allow the bipyridine to fully coordinate with the metal phthalocyanine complex on the surface of the modified carbon nanotubes. Finally, add 0.6 g of Karstedt platinum catalyst (Pt content 2%), pass through a thin tube three times at 30°C, and quickly sheet the product. Place the rubber compound in a mold and vulcanize it at 130°C and 5 MPa for 25 minutes. After demolding, vulcanize it in a 180°C hot air oven for 4 hours in a second stage to obtain the tear-resistant silicone rubber product.

[0041] Example 3: A tear-resistant silicone rubber was prepared according to the following method: 1000 g of methyl vinyl silicone rubber (Mingyi Silicon Industry MY 3112-3, vinyl content 0.19-0.24 mol%) and 78 g of alkoxy-modified fluorosilicone rubber (prepared in Preparation Example 3-3) were added to a two-roll mill. The roll temperature was controlled at 50 ℃. After the roll wrapping was stable, 20 g of α,ω-divinyl silicone oil (DMS-V1000) and 100 g of carbon black (average particle size 20-25 nm) were added. The mixture was passed through a thin mill 5 times and then rolled in a triangular shape 3 times. After 20 minutes of mixing, the masterbatch was obtained. Subsequently, 100 g of modified carbon nanotubes (prepared in Preparation Example 2-3), 80 g of interface modifier (prepared in Preparation Example 1-3), and 60 g of hydrogen-containing silicone oil A (RH-LHC-3, hydrogen content 0.8 wt%) were added. The mixture was continued to be mixed for 12 minutes until homogeneous. The mixture was then allowed to stand at room temperature for 40 minutes to allow the bipyridine to fully coordinate with the metal phthalocyanine complex on the surface of the modified carbon nanotubes. Finally, add 2.8 g of Karstedt platinum catalyst (Pt content 2%), pass through a thin tube three times at 35°C, and quickly sheet the product. Place the rubber compound in a mold and vulcanize it at 170°C and 13 MPa for 10 minutes. After demolding, vulcanize it in a 220°C hot air oven for 2 hours to obtain tear-resistant silicone rubber products.

[0042] Example 4, a tear-resistant silicone rubber, differs from Example 1 in that an equal amount of methyl vinyl trifluoropropyl silicone rubber (Mn≈600,000, vinyl content 0.15 mol%) is used to replace the alkoxy-modified fluorosilicone rubber of Preparation Example 3-1.

[0043] Example 5, a tear-resistant silicone rubber, differs from Example 1 in that an equal amount of alkoxy-modified silicone rubber prepared in Example 3-4 is used instead of the alkoxy-modified fluorosilicone rubber prepared in Example 3-1.

[0044] Example 6, a tear-resistant silicone rubber, differs from Example 1 in that an equal amount of methyl vinyl silicone rubber (Mingyi Silicon Industry MY 3110-2, vinyl content 0.13-0.18 mol%) is used to replace the alkoxy-modified fluorosilicone rubber of Preparation Example 3-1.

[0045] Example 7, a tear-resistant silicone rubber, differs from Example 1 in that an equal amount of fumed silica (average particle size 20-25 nm) is used instead of carbon black (average particle size 20-25 nm).

[0046] Example 8, a tear-resistant silicone rubber, differs from Example 1 in that the interface modifier of Preparation Example 1-1 is replaced with an equal amount of the interface modifier of Preparation Example 1-4.

[0047] Comparative Example Comparative Example 1, a tear-resistant silicone rubber, differs from Example 1 in that the modified carbon nanotubes of Preparation Example 2-1 are replaced with an equal amount of the modified carbon nanotubes of Preparation Example 2-4.

[0048] Comparative Example 2, a tear-resistant silicone rubber, differs from Example 1 in that the modified carbon nanotubes of Preparation Example 2-1 are replaced with an equal amount of the modified carbon nanotubes of Preparation Example 2-5.

[0049] Comparative Example 3, a tear-resistant silicone rubber, differs from Example 1 in that an equal amount of end-side hydrogen-containing silicone oil (Ningbo Runhe RH-LHC-3, hydrogen content 0.8 wt%) replaces the interface modifier of Preparation Example 1-1.

[0050] Comparative Example 4, a tear-resistant silicone rubber, differs from Example 1 in that the interface modifier of Preparation Example 1-1 was not added.

[0051] Performance testing Experiment 1: Tear Resistance Test Sample preparation: The vulcanized rubber sheets obtained from each example and comparative example were cut into right-angled samples (total length 100 mm, width 10 mm, thickness 2.0 ± 0.2 mm, cut depth 2 mm), and 5 parallel samples were prepared for each group.

[0052] Test Procedure: Following the specifications in GB / T 529–2008 "Determination of Tear Strength of Vulcanized Rubber or Thermoplastic Rubber", the test was conducted using a universal testing machine (Instron 5967) at a tensile speed of 500 mm / min. The maximum tear force (N) was recorded, and the tear strength was calculated using the formula: T = F / d (unit: kN / m); Where F is the maximum tear force (N), d is the sample thickness (mm), and the average value of 5 samples is taken as the tear strength of this group.

[0053] Experiment 2: Toughness Test Sample preparation: Five dumbbell-shaped samples (Type 1) with a thickness of 2.0 ± 0.2 mm were cut from the silicone rubber samples of each example and comparative example. The samples were conditioned for 24 hours under a standard environment of 23 ± 2 °C and 50 ± 5% relative humidity.

[0054] Test Procedure: Following the specifications in JISK 6251:2017 "Vulcanized or Thermoplastic Rubber—Determination of Tensile Stress-Strain Properties", a universal testing machine was used, with the tensile speed set to 500±50 mm / min. The maximum tensile force at fracture was recorded, and the tensile strength (unit: MPa) was calculated. Simultaneously, the elongation at fracture was recorded, and the elongation at break (unit: %) was calculated. The result was the arithmetic mean of five specimens.

[0055] Test 3: Solvent Resistance Test Sample preparation: The vulcanized rubber sheets obtained from each example and comparative example were cut into right-angled samples (total length 100 mm, width 10 mm, thickness 2.0 ± 0.2 mm, cut depth 2 mm), and 10 parallel samples were prepared for each group.

[0056] Test Procedure: Completely immerse the sample in a sealed container filled with anhydrous ethanol. Place the container in a constant temperature environment of 40±1℃ for 96 hours. After immersion, remove the sample, quickly blot the surface liquid with filter paper, and weigh it within 30 seconds. Then, allow it to stand for 30 minutes to recover as required by the standard. For the recovered samples, test their tear strength according to the method in Test 1, and calculate the performance retention rate (%) using the formula: Tear Strength Retention Rate = (Average Tear Strength After Immersion / Average Tear Strength Before Immersion) × 100%.

[0057] Table 1. Performance Test Results

[0058] Compared to Example 1, Example 4, which used unmodified fluorosilicone rubber instead of alkoxy-modified fluorosilicone rubber, showed a significant decrease in tear retention after solvent immersion. Alkoxy modification is crucial for constructing a hydrophobic barrier. This may be because, although unmodified fluorosilicone rubber has low surface energy, it cannot react with the carbon black distributed around the carbon nanotubes to form a hydrophobic barrier, allowing the solvent to easily penetrate along the phase interface and disrupt the metal-nitrogen coordination structure. Example 5 used alkyl-modified methyl vinyl silicone rubber. While its tear strength was maintained, the tear retention rate also decreased significantly, indicating that the crosslinking of alkoxy groups with carbon black plays an important role in improving tear strength and impermeability. However, the use of fluorosilicone rubber is also extremely critical for constructing a hydrophobic barrier in the coordination system. Example 6 did not use fluorosilicone rubber, and its tear retention rate also decreased significantly, with performance degradation similar to that of Example 4. This indicates that using conventional fluorosilicone rubber in Example 4 did not significantly improve the material's tear retention rate. Therefore, fluorosilicone rubber needs to synergistically with carbon black to construct a hydrophobic barrier to achieve the desired effect. Example 7 uses silica instead of carbon black, and its tear strength is maintained. However, the solvent resistance tear retention rate is the worst among all examples, indicating that the absence of carbon black and fluorosilicone cannot build a local hydrophobic barrier, causing polar solvents to directly contact the coordination interface, resulting in the failure of coordination bonds and the inability to maintain its tear strength.

[0059] Compared to Example 1, the interface modifier prepared using side-chain hydrogen-containing silicone oil in Example 8 showed a slight decrease in various properties, especially tear strength, indicating that the end-chain hydrogen-containing silicone oil, due to its higher reactivity and crosslinking efficiency, is more conducive to the formation of a dense network.

[0060] Compared to Example 1, Comparative Example 1, which used SDS to physically coat CNTs, showed a significant decrease in tear strength, indicating that physical adsorption cannot effectively transfer stress. This may be because SDS has no chemical or coordination interaction with the silicone rubber matrix, making it easy for CNTs to slip under stress, resulting in poor reinforcement. Comparative Example 2, which used a covalently grafted silane coupling agent, showed slightly higher tear strength and tensile strength, but a significantly deteriorated elongation at break, indicating that the rigid covalent interface caused material embrittlement. This may be because the acidification pretreatment destroyed the CNT structure, and the Si-OC bond is irreversible, failing to dissipate impact energy, which contrasts sharply with the "dynamic reversible coordination" of this invention.

[0061] Compared to Example 1, Comparative Example 3, which uses ordinary hydrogen-containing silicone oil instead of the interface modifier, showed a significant decrease in tear strength, indicating that the bipyridine group is key to achieving the coordination bridging of carbon nanotubes and rubber. This may be because ordinary hydrogen-containing silicone oil only participates in crosslinking and cannot form an interface with the carbon nanotubes with metal phthalocyanine complexes attached to their surface, rendering the carbon nanotubes inert fillers. Comparative Example 4 exhibited the lowest tear strength. This indicates that the complete absence of the interface modifier prevented the formation of the dynamic coordination interface required in this application. The modified carbon nanotubes were merely physical fillers in the matrix, and may even have become defect points due to aggregation. Their tear strength was close to that of the matrix itself, fully demonstrating the indispensable and crucial role of the interface modifier in this invention.

[0062] Furthermore, the solvent resistance of Comparative Examples 1 to 4 did not change significantly, and the tear strength retention rate after immersion in ethanol did not decrease significantly, indicating that polar solvents have little effect on silicone rubber systems without a coordination network.

[0063] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A tear-resistant silicone rubber, characterized in that, The raw materials include the following parts by weight: 100 parts of raw silicone rubber, 2-6 parts of hydrogen-containing silicone oil A, 3-8 parts of interface modifier, 0.05-0.3 parts of platinum catalyst, 5-10 parts of carbon nanotubes, 5-10 parts of carbon black, and 1-2 parts of structure control agent; the carbon nanotubes have metal phthalocyanine complexes attached to their surfaces, the interface modifier molecules have Si-H and bipyridine groups, and the interface modifier is prepared by hydrosilylation of hydrogen-containing silicone oil B and vinyl bipyridine.

2. The tear-resistant silicone rubber according to claim 1, characterized in that, The hydrogen-containing silicone oil B is a hydrogen-containing silicone oil with Si-H in both end side chains, and the molar ratio of Si-H to vinyl bipyridine in the hydrogen-containing silicone oil B is 3-5:1-2.

3. The tear-resistant silicone rubber according to claim 1, characterized in that, The hydrosilylation reaction temperature is 80℃~120℃, and the reaction time is 2~5 hours.

4. The tear-resistant silicone rubber according to claim 1, characterized in that, The raw silicone rubber is selected from one or more of methyl vinyl silicone rubber, methyl vinyl phenyl silicone rubber, and methyl vinyl trifluoropropyl silicone rubber.

5. The tear-resistant silicone rubber according to claim 1, characterized in that, The metal phthalocyanine complex is zinc phthalocyanine and / or copper phthalocyanine.

6. The tear-resistant silicone rubber according to claim 1, characterized in that, The tear-resistant silicone rubber contains 5 to 8 parts of alkoxy-modified fluorosilicone rubber.

7. The tear-resistant silicone rubber according to claim 6, characterized in that, The alkoxy-modified fluorosilicone rubber is prepared by hydrosilylation of hydrogen-containing alkoxysilane with methyl vinyltrifluoropropyl silicone rubber.

8. The tear-resistant silicone rubber according to claim 7, characterized in that, The hydrogen-containing alkoxysilane is selected from one or more of triethoxysilane, trimethoxysilane, methyldimethoxysilane, and ethyldimethoxysilane.

9. The tear-resistant silicone rubber according to claim 7, characterized in that, The mass ratio of the methyl vinyl trifluoropropyl silicone rubber to the hydrogen-containing alkoxysilane is 100:1 to 3.

10. A method for preparing tear-resistant silicone rubber, characterized in that, include: According to the raw material ratio of the tear-resistant silicone rubber according to any one of claims 1 to 9, the raw silicone rubber and fluorosilicone rubber are placed in a two-roll mill or internal mixer and mixed at 30 to 50°C until the mixture is stable under the rolls; then the structure control agent and carbon black are added and the mixture is continued to be mixed for 10 to 20 minutes to obtain the masterbatch. Carbon nanotubes, an interface modifier, and hydrogen-containing silicone oil A are added to the masterbatch, and the mixture is further mixed at 30–50 °C for 5–15 minutes; then the mixture is allowed to stand at room temperature for 20–60 minutes to obtain a premixed rubber compound. The premixed rubber compound is cooled to ≤40℃, a platinum catalyst is added, and the mixture is rapidly passed through a thin tube 2-4 times at low temperature. After mixing evenly, the mixture is immediately sheeted to obtain a vulcanizable compound. The compound is then placed in a mold and placed in a flat vulcanizing machine. It is vulcanized for 5-30 minutes at a pressure of 1-15MPa and a temperature of 120-180℃ to complete the first stage of vulcanization. The vulcanized sample is then placed in a hot air circulating oven and baked at atmospheric pressure and 180-220℃ for 2-4 hours.

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