A rubber weather strip and a method of making the same

Abstract

This invention relates to the field of rubber technology, specifically to a rubber sealing strip and its preparation method. The rubber sealing strip, by weight, comprises the following components: 50-70 parts EPDM rubber, 30-50 parts nitrile rubber, 15-25 parts core-shell composite filler, 5-10 parts carbon black, 3-8 parts modified boron nitride nanosheets, 1.5-3 parts peroxide vulcanizing agent, 1-2 parts co-crosslinking agent, 1-2 parts antioxidant, and 1-3 parts lubricant; wherein the core-shell composite filler is a composite material with porous nano-silica as the core, an organosiloxane network, and embedded nano-tungsten disulfide as the shell. The rubber sealing strip provided by this invention solves the problems of insufficient mechanical properties, wear resistance, and thermal stability, as well as poor filler dispersion in traditional rubber sealing strips; it improves the tensile strength, wear resistance, and heat aging resistance of the rubber.

Description

Technical Field

[0001] This invention relates to the field of rubber technology, specifically to a rubber sealing strip and its preparation method. Background Technology

[0002] Rubber sealing strips, as a crucial sealing material, play an irreplaceable role in numerous fields such as automotive, construction, aerospace, and machinery manufacturing. Their core function is to prevent leakage of gases, liquids, and other media, while also providing auxiliary functions such as shock absorption and sound insulation. With the increasing demands for sealing performance across industries, rubber sealing strips not only need excellent mechanical properties to withstand complex external forces, but also good wear resistance to adapt to long-term friction environments, and outstanding thermal stability to maintain performance under high-temperature conditions.

[0003] While existing rubber sealing strips meet the needs of some application scenarios to a certain extent, they still have many shortcomings in terms of overall performance, specifically in the following aspects: Traditional rubber sealing strips suffer from weak interfacial bonding between the filler and the rubber matrix, resulting in poor filler dispersion within the rubber. This leads to the rubber's tensile strength, tear strength, and other mechanical properties failing to reach ideal levels. Under significant external forces, they are prone to cracking or deformation, affecting sealing performance and service life. Furthermore, existing rubber sealing strips often exhibit high wear rates under long-term friction environments. This is mainly due to the weak interaction force between the filler and the rubber matrix, making the filler prone to detachment during friction. Simultaneously, the rubber matrix itself has limited wear resistance and cannot effectively resist the effects of friction. Under high-temperature conditions, traditional rubber sealing strips are prone to softening, deformation, or a sharp decline in performance. This is because the rubber matrix is ​​susceptible to thermal aging reactions at high temperatures, leading to molecular chain breakage and reduced cross-linking density, thus affecting the rubber's mechanical and sealing properties. In addition, the difference in thermal expansion coefficients between the filler and the rubber matrix can also cause interfacial debonding, further exacerbating performance degradation. Based on these findings, this invention proposes a rubber sealing strip and its preparation method. Summary of the Invention

[0004] This invention proposes a rubber sealing strip and its preparation method, which solves the problems of insufficient mechanical properties, wear resistance, thermal stability and poor filler dispersion of traditional rubber sealing strips; it improves the tensile strength, wear resistance and heat aging resistance of rubber, improves the dispersion and interfacial bonding of fillers in the rubber matrix, effectively transfers stress, and endows the rubber sealing strip with excellent comprehensive properties of high strength, high wear resistance and heat aging resistance.

[0005] The technical solution of the present invention is as follows: In a first aspect, the present invention proposes a rubber sealing strip, comprising, by weight, the following components: 50-70 parts of EPDM rubber, 30-50 parts of nitrile rubber, 15-25 parts of core-shell composite filler, 5-10 parts of carbon black, 3-8 parts of modified boron nitride nanosheets, 1.5-3 parts of peroxide vulcanizing agent, 1-2 parts of crosslinking agent, 1-2 parts of antioxidant, and 1-3 parts of lubricant; wherein the core-shell composite filler is a composite material with porous nano-silica as the core, an organosiloxane network, and embedded nano-tungsten disulfide as the shell.

[0006] As a further technical solution, the preparation method of the core-shell structured composite filler includes: (1) Disperse porous nano-silica in an ethanol-water mixed solvent and sonicate to form a uniform suspension; (2) Add the silane coupling agent containing amino or epoxy groups and the nano tungsten disulfide sheet dispersion to the suspension in step (1), and stir and react for 4-8 hours under pH 4-5 and 60-80℃ conditions to hydrolyze and condense the silane coupling agent, forming an organosilicon hybrid network shell coating nano tungsten disulfide on the surface and in the pores of silica. (3) The product obtained in step (2) is separated, washed, and vacuum dried at 80-100℃. After grinding, the core-shell structure composite filler is obtained.

[0007] As a further technical solution, in step (1), the volume ratio of ethanol to water in the ethanol-water mixed solvent is 6-10:1; the concentration of the porous nano silica in the suspension is 20-60 g / L.

[0008] As a further technical solution, the silane coupling agent in step (2) is γ-aminopropyltriethoxysilane or γ-(2,3-epoxypropoxy)propyltrimethoxysilane, the thickness of the nano-tungsten disulfide sheets is 5-20 nm, and the sheet diameter is 50-200 nm; the pore size of the porous nano-silica is 5-15 nm, and the specific surface area is 300-600 m². 2 / g.

[0009] As a further technical solution, in step (2), the mass concentration of tungsten disulfide nanosheets in the dispersion is 1-5 g / L; the mass ratio of tungsten disulfide nanosheets to porous nano-silica is 1:5-20; the amount of silane coupling agent is 2%-8% of the total mass of porous nano-silica and tungsten disulfide nanosheets; and the reagent used to adjust the pH is an acetate-sodium acetate buffer solution or dilute nitric acid.

[0010] As a further technical solution, in step (3), the method for preparing the modified boron nitride nanosheets is as follows: disperse the boron nitride nanosheets in an ethanol solution containing silane coupling agent KH-570, reflux at 70-80℃ for 6-12h, centrifuge, wash and dry after reaction to obtain modified boron nitride nanosheets with vinyl groups grafted on the surface.

[0011] As a further technical solution, the mass concentration of KH-570 silane coupling agent in the ethanol solution is 5%-15%; the mass ratio of boron nitride nanosheets to KH-570 silane coupling agent is 5-10:1; and the dispersion concentration of boron nitride nanosheets in the ethanol solution is 10-30 g / L.

[0012] As a further technical solution, the peroxide vulcanizing agent is at least one of dicumyl peroxide and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; the co-crosslinking agent is triallyl isocyanurate or trimethylolpropane trimethacrylate.

[0013] Secondly, this invention proposes a method for preparing a rubber sealing strip, the steps of which include: S1. First stage of mixing: Put EPDM rubber and nitrile rubber into an internal mixer and plasticize at 70-90℃ for 1-2 minutes; add antioxidant and lubricant in sequence and mix for 3-5 minutes; then add core-shell structured composite filler and modified boron nitride nanosheets and mix for 2-4 minutes; discharge the rubber to obtain masterbatch and cool and stand; S2. Two-stage mixing: Put the masterbatch back into the internal mixer or open mill, add carbon black, peroxide vulcanizing agent and crosslinking agent, and mix evenly at 60-80℃ to obtain the final compound. S3. Extrusion and vulcanization: The final rubber compound is fed into an extruder and extruded through a die to form a sealing strip preform; the preform is then sent to a vulcanizing tank or a continuous vulcanization production line for vulcanization to obtain the rubber sealing strip.

[0014] As a further technical solution, the vulcanization is carried out at 160-180℃ and 8-15 MPa pressure for 10-20 minutes.

[0015] The working principle and beneficial effects of this invention are as follows: This invention prepares a composite filler with a porous nano-silica core and an organosilicon hybrid network coated with nano-tungsten disulfide as the shell, and combines it with modified boron nitride nanosheets grafted with vinyl groups. This combination provides a synergistic enhancement at the structural level. The porous nano-silica core provides basic skeletal support for the composite material, and its high specific surface area and specific pore size are conducive to loading other functional components. The organosilicon hybrid network shell coated with nano-tungsten disulfide not only utilizes the solid lubrication properties of nano-tungsten disulfide, but also achieves good interfacial bonding with the rubber matrix through the organosilicon network. At the same time, the organosilicon network can participate in the cross-linking reaction during rubber vulcanization, enhancing the interaction with the rubber matrix. The modified boron nitride nanosheets grafted with vinyl groups enable them to participate in the vulcanization cross-linking network, improving dispersibility and interfacial bonding in the rubber matrix. Together with the core-shell structure composite filler, they improve the overall performance of the rubber sealing strip.

[0016] In this invention, the core-shell composite filler plays a multifaceted synergistic reinforcing role in the rubber matrix. The porous nano-silica core has a high specific surface area, enabling it to physically adsorb and mechanically interlock with the rubber molecular chains, enhancing the reinforcing effect and improving mechanical properties such as tensile strength. The organosilicon hybrid network shell coating the core surface has two main advantages: firstly, the organosilicon component has good compatibility with the rubber matrix, reducing interfacial energy and promoting uniform dispersion of the filler in the rubber; secondly, the organosilicon network participates in cross-linking reactions during vulcanization, forming chemical bonds that further enhance the interfacial bonding between the filler and the rubber, effectively transferring stress and improving the rubber's wear resistance and tear resistance. Nano-tungsten disulfide embedded in the organosilicon network shell acts as a solid lubricant. During rubber friction, it forms a lubricating film on the contact surface, reducing the coefficient of friction and wear. Simultaneously, its uniform dispersion within the shell avoids the problem of agglomeration that occurs with simple physical mixing, fully utilizing its lubricating effect and synergistically improving the wear resistance of the rubber with the organosilicon network.

[0017] In this invention, the vinyl groups grafted onto the surface of modified boron nitride nanosheets enable them to participate in the peroxide vulcanization system of rubber. During vulcanization, the vinyl groups react with free radicals generated by the peroxide vulcanizing agent, chemically bonding the boron nitride nanosheets into the rubber crosslinking network. This chemical bonding not only improves the dispersibility of boron nitride nanosheets in the rubber matrix, avoiding the problem of insufficient reinforcement and wear resistance potential caused by poor dispersibility and weak interfacial bonding in the unmodified form, but also enhances the interaction between the boron nitride nanosheets and the rubber molecular chains, effectively transferring stress and improving the tensile strength and wear resistance of the rubber. Simultaneously, the modified boron nitride nanosheets form a uniformly dispersed reinforcing phase in the rubber matrix, interpenetrating with the rubber crosslinking network, further improving the ultimate wear resistance and dimensional stability of the composite material at high temperatures. Synergistically working with the core-shell structured composite filler, it imparts excellent high strength, high wear resistance, and heat aging resistance to the rubber sealing strip.

[0018] In this invention, the core-shell composite filler and modified boron nitride nanosheets exhibit a synergistic effect in improving the thermal stability of rubber sealing strips. In the core-shell structure, the porous nano-silica core possesses high thermal stability, maintaining structural stability at high temperatures and providing thermal stability support for the rubber. The organosilicon hybrid network shell exhibits good heat resistance and chemical stability, resisting decomposition at high temperatures and protecting nano-tungsten disulfide from oxidation and failure. Simultaneously, the chemical bond between the organosilicon network and the rubber matrix remains stable at high temperatures, maintaining good interfacial bonding, preventing interfacial debonding due to thermal expansion differences, and reducing performance degradation during thermal aging. The modified boron nitride nanosheets themselves possess excellent thermal conductivity and thermal stability. After uniform dispersion in the rubber matrix, they can rapidly conduct heat, reducing the internal temperature gradient of the rubber and minimizing the damage to rubber performance caused by localized overheating. Furthermore, their chemical bond with the rubber crosslinking network remains stable at high temperatures, further enhancing the dimensional stability and mechanical properties of the rubber at high temperatures. The synergistic effect of the two effectively improves the heat aging resistance of rubber sealing strips, solving the problem of traditional rubber sealing strips being prone to aging and rapid performance degradation at high temperatures. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should also be noted that the nitrile rubber was purchased from Tianjin Tianxingjian Rubber Products Co., Ltd.; and the ethylene propylene diene monomer (EPDM) rubber was purchased from ExxonMobil, with the grade being 2504W.

[0021] Example 1 This embodiment provides a rubber sealing strip, which, by weight, comprises the following components: 60 parts ethylene propylene diene monomer (EPDM) rubber, 40 parts nitrile rubber (NBR), 20 parts core-shell composite filler, 8 parts carbon black (N330), 5 parts modified boron nitride nanosheets, 2.5 parts peroxide vulcanizing agent (dicumyl peroxide, DCP), 1.5 parts co-crosslinking agent (tracene propyl isocyanurate, TAIC), 1.5 parts antioxidant (2,2,4-trimethyl-1,2-dihydroquinoline polymer, RD), and 2 parts lubricant (zinc stearate). The preparation steps of the core-shell structured composite filler include: Porous nano-silica with a pore size of 10±2nm and a specific surface area of ​​450m² 2 / g, average particle size 80nm; nano tungsten disulfide sheet thickness 10±5nm, sheet diameter 100±50nm; 40g of porous nano-silica was dispersed in 800mL of ethanol-water mixed solvent (700mL ethanol, 100mL water) and ultrasonicated (500W power, 40kHz frequency) for 30min to form a uniform suspension (concentration 50g / L). 100mL of nano-tungsten disulfide sheet dispersion (concentration 3g / L, containing 0.3g nano-tungsten disulfide) was added to the suspension. 2.8g of KH-550 silane coupling agent (4% of the total mass of porous nano-silica and nano-tungsten disulfide) was added. The pH was adjusted to 4.5 with acetate-sodium acetate buffer solution. The reaction was carried out in a 75℃ constant temperature water bath with stirring at 300rpm for 6h. After the reaction was completed, the product was separated by high-speed centrifugation at 8000rpm for 10min, washed three times with anhydrous ethanol, and dried in a 90℃ vacuum drying oven for 12h to constant weight to obtain the core-shell structured composite filler, denoted as CS-1. The preparation steps of the modified boron nitride nanosheets include: Boron nitride nanosheets: 5 layers thick, lateral dimension 2μm; 15 g of boron nitride nanosheets were dispersed in 750 mL of anhydrous ethanol (concentration 20 g / L) and sonicated for 1 h. 2 g of KH-570 silane coupling agent (mass concentration approximately 2.6%) was added, with a boron nitride nanosheet to KH-570 mass ratio of 7.5:1. The reaction was refluxed at 75 °C for 9 h, followed by condensation and reflux. After the reaction was completed, the nanosheets were centrifuged at 6000 rpm for 15 min. The nanosheets were washed three times with ethanol and then vacuum dried at 80 °C for 8 h to obtain modified boron nitride nanosheets with vinyl groups grafted onto their surface, denoted as m-BN. The method for preparing the rubber sealing strip in this embodiment includes the following steps: The internal mixer was initially set at 75℃. EPDM and NBR were added and plasticized for 1.5 min. Antioxidant RD and lubricant were added and mixed for 4 min. Core-shell composite filler CS-1 and modified boron nitride nanosheets m-BN were added and mixed for 3 min. The discharge temperature was 110℃ to obtain the masterbatch. The masterbatch was cooled and left to stand at room temperature for 4 h. The open mill was set with a roller temperature of 65℃. The masterbatch was fed into the open mill and 8 parts of carbon black were added in three thin passes. The mixture was mixed until evenly dispersed and then dicumyl peroxide was added. (DCP), TAIC, cut 5 times on each side, and perform 3 triangular wrapping operations to ensure uniform mixing; cut into sheets with a thickness of about 4mm to obtain the final rubber compound; feed the final rubber compound into a cold feed extruder, with the first stage at 65°C, the second stage at 70°C, the third stage at 75°C, and the die head at 80°C, and extrude the preform through a special die for door and window sealing strips. The preform enters a continuous vulcanization production line, where it is vulcanized at 170°C and 12MPa for 15 minutes. After cooling and cutting, the finished rubber sealing strip is obtained.

[0022] Example 2 This embodiment provides a rubber sealing strip, which, by weight, comprises the following components: 70 parts of ethylene propylene diene monomer (EPDM) rubber, 30 parts of nitrile butadiene rubber (NBR), 15 parts of core-shell structured composite filler, 5 parts of carbon black (N330), 8 parts of modified boron nitride nanosheets, 1.5 parts of peroxide vulcanizing agent (dicumyl peroxide, DCP), 1 part of co-crosslinking agent (tracene propyl isocyanurate, TAIC), 1 part of antioxidant (2,2,4-trimethyl-1,2-dihydroquinoline polymer, RD), and 1 part of lubricant (zinc stearate). The preparation steps of the core-shell structured composite filler include: Porous nano-silica with a pore size of 5nm and a specific surface area of ​​600m² 2 / g, average particle size 50nm; nano tungsten disulfide sheet thickness 5nm, sheet diameter 50nm; 30 g of porous nano-silica was dispersed in 1000 mL of an ethanol-water mixture (857 mL ethanol, 143 mL water, volume ratio 6:1) and sonicated (500 W power, 40 kHz frequency) for 30 min to form a uniform suspension (concentration 30 g / L). 150 mL of a nano-tungsten disulfide sheet dispersion (concentration 1 g / L, containing 0.15 g nano-tungsten disulfide) was added to the suspension (nano-tungsten disulfide to porous nano-silica mass ratio 1:20). Add 0.37 g γ-aminopropyltriethoxysilane (accounting for 2% of the total mass of porous nano-silica and nano-tungsten disulfide); adjust the pH to 4.0 with acetate-sodium acetate buffer solution; stir at 300 rpm for 8 h in a 60℃ constant temperature water bath; after the reaction is completed, separate the product by high-speed centrifugation at 8000 rpm for 10 min, wash 3 times with anhydrous ethanol, and dry in a vacuum drying oven at 80℃ for 12 h to constant weight to obtain the core-shell structured composite filler, denoted as CS-2; The preparation steps of the modified boron nitride nanosheets include: Boron nitride nanosheets: 3 layers thick, 1 μm lateral dimension; 10 g of boron nitride nanosheets were dispersed in 1000 mL of anhydrous ethanol (concentration 10 g / L) and sonicated for 1 h. 2 g of KH-570 silane coupling agent (mass concentration 2%, boron nitride nanosheets to KH-570 mass ratio 5:1) was added. The mixture was refluxed at 70 °C for 12 h and then refluxed again. After the reaction was completed, the mixture was centrifuged at 6000 rpm for 15 min. The mixture was washed three times with ethanol and dried under vacuum at 80 °C for 8 h to obtain modified boron nitride nanosheets with vinyl groups grafted on the surface, denoted as m-BN-2. The method for preparing the rubber sealing strip in this embodiment includes the following steps: The internal mixer was initially set at 70℃. EPDM and NBR were added and plasticized for 1 minute. Antioxidant RD and lubricant were added and mixed for 3 minutes. Core-shell composite filler CS-2 and modified boron nitride nanosheets m-BN-2 were added and mixed for 2 minutes. The discharge temperature was 105℃ to obtain the masterbatch. The masterbatch was cooled and left to stand at room temperature for 4 hours. The open mill was set with a roller temperature of 60℃. The masterbatch was fed into the open mill, and carbon black was added in three thin passes, mixing until evenly dispersed. Dicumyl peroxide was added. The rubber is mixed thoroughly with DCP and TAIC cutters, 5 times each on the left and right sides, and 3 times with triangular wrapping to ensure uniform mixing. The rubber is then sheeted to a thickness of about 4mm to obtain the final rubber compound. The final rubber compound is fed into a cold feed extruder at 60°C for the first stage, 65°C for the second stage, 70°C for the third stage, and 75°C for the die head. The extruded preform is then extruded through a special die for door and window sealing strips. The preform enters a continuous vulcanization production line and is vulcanized at 160°C and 8MPa for 20 minutes. After cooling and cutting, the finished rubber sealing strip is obtained.

[0023] Example 3 This embodiment provides a rubber sealing strip, which, by weight, comprises the following components: 50 parts of ethylene propylene diene monomer (EPDM) rubber, 50 parts of nitrile rubber (NBR), 25 parts of core-shell composite filler, 10 parts of carbon black (N330), 3 parts of modified boron nitride nanosheets, 3 parts of peroxide vulcanizing agent (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), 2 parts of co-crosslinking agent (trimethylolpropane trimethacrylate), 2 parts of antioxidant (2,2,4-trimethyl-1,2-dihydroquinoline polymer, RD), and 3 parts of lubricant (zinc stearate). The preparation steps of the core-shell structured composite filler include: Porous nano-silica with a pore size of 15nm and a specific surface area of ​​300m² 2 / g, average particle size 100nm; nano tungsten disulfide sheet thickness 20nm, sheet diameter 200nm; 60g of porous nano-silica was dispersed in 1000mL of an ethanol-water mixture (909mL ethanol, 91mL water, volume ratio 10:1) and sonicated (500W power, 40kHz frequency) for 30min to form a uniform suspension (concentration 60g / L). 120mL of a nano-tungsten disulfide sheet dispersion (concentration 5g / L, containing 0.6g nano-tungsten disulfide) was added to the suspension (nano-tungsten disulfide to porous nano-silica mass ratio 1:10). Add 4.75g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (8% of the total mass of porous nano-silica and nano-tungsten disulfide); adjust the pH to 5.0 with dilute nitric acid; stir at 300rpm for 4h in a constant temperature water bath at 80℃; after the reaction is complete, separate the product by high-speed centrifugation at 8000rpm for 10min, wash 3 times with anhydrous ethanol, and dry in a vacuum drying oven at 100℃ for 12h to constant weight to obtain the core-shell structured composite filler, denoted as CS-3; The preparation steps of the modified boron nitride nanosheets include: Boron nitride nanosheets: 10 layers thick, 3 μm lateral dimension; 30 g of boron nitride nanosheets were dispersed in 1000 mL of anhydrous ethanol (concentration 30 g / L) and sonicated for 1 h. 3 g of KH-570 silane coupling agent (mass concentration 3%, boron nitride nanosheets to KH-570 mass ratio 10:1) was added. The mixture was refluxed at 80 °C for 6 h and then refluxed again. After the reaction was completed, the mixture was centrifuged at 6000 rpm for 15 min. The mixture was washed three times with ethanol and dried under vacuum at 80 °C for 8 h to obtain modified boron nitride nanosheets with vinyl groups grafted on the surface, denoted as m-BN-3. The method for preparing the rubber sealing strip in this embodiment includes the following steps: The internal mixer is initially set at 90℃. EPDM and NBR are added and plasticized for 2 minutes. Antioxidant RD and lubricant are added and mixed for 5 minutes. Core-shell composite filler CS-3 and modified boron nitride nanosheets m-BN-3 are added and mixed for 4 minutes. The discharge temperature is 115℃ to obtain the masterbatch. The masterbatch is cooled and left to stand at room temperature for 4 hours. The internal mixer is set at 80℃, and the masterbatch is put back into the internal mixer. Carbon black, peroxide vulcanizing agent and crosslinking agent are added and mixed evenly before discharge. The masterbatch is sheeted to a thickness of about 4mm to obtain the final compound. The final compound is fed into a cold feed extruder at 70℃ for the first stage, 75℃ for the second stage, 80℃ for the third stage, and 85℃ for the die head. The preform is extruded through a special die for door and window sealing strips. The preform is sent to a vulcanizing tank for vulcanization at 180℃ and 15MPa for 10 minutes. After cooling and cutting, the finished rubber sealing strip is obtained.

[0024] Example 4 Based on Example 1, adjustments were made. Unlike Example 1, in Example 4, when preparing the core-shell composite filler, no nano-tungsten disulfide sheet dispersion was added; only the hydrolysis and condensation reaction of the silane coupling agent on the silica surface was carried out. The resulting product was designated CS-4, replacing CS-1 in Example 1, and otherwise remained the same as in Example 1.

[0025] Comparative Example 1 Based on Example 1, adjustments were made. The difference from Example 1 is that in Comparative Example 1, 20 parts of core-shell structured composite filler (CS-1) were replaced with 10 parts of porous nano-silica and 10 parts of nano-tungsten disulfide sheets, while the rest were the same as in Example 1.

[0026] Comparative Example 2 Based on Example 1, adjustments were made. Unlike Example 1, in Comparative Example 2, all 20 parts of core-shell composite filler (CS-1) and 5 parts of modified boron nitride nanosheets (m-BN) were replaced with an equal amount (25 parts) of material with a specific surface area of ​​200 m². 2 / g ordinary precipitated silica, the rest is the same as in Example 1.

[0027] Comparative Example 3 Based on Example 1, the following adjustments were made: In Comparative Example 3, the modified boron nitride nanosheets (m-BN) were replaced with an equal amount of unmodified boron nitride nanosheets, while the rest remained the same as in Example 1.

[0028] Comparative Example 4 Based on Example 1, adjustments were made. Unlike Example 1, no core-shell composite filler was added in Comparative Example 4. Otherwise, it was the same as Example 1.

[0029] Comparative Example 5 Based on Example 1, adjustments were made. The difference between Example 5 and Example 1 is that no modified boron nitride nanosheets were added. Otherwise, the same as Example 1 was used.

[0030] Test example: The rubber sealing strips prepared in Examples 1-4 and Comparative Examples 1-5 were tested as follows: tensile strength, elongation at break (according to GB / T 528-2009) and hardness (Shore A, according to GB / T531.1-2008); Abrasion resistance: Tested according to GB / T1689-2014 "Determination of abrasion resistance of vulcanized rubber"; the volume loss of the sample after a specified stroke (1.61km) was measured at 15° and 26.7N. Heat resistance to air aging: Tested according to GB / T3512-2014 "Accelerated aging and heat resistance test of vulcanized rubber or thermoplastic rubber in hot air", aged at 100℃ for 165h, and the change rate of tensile strength (%), change rate of elongation at break (%), and change of hardness (degrees) were measured.

[0031] The results are shown in Table 1 below: Table 1 Acid Resistance

[0032] Based on the above, it can be seen that the performance of Comparative Example 1 is inferior to that of Example 1 in all aspects. The wear resistance and tensile strength are significantly reduced, and the elongation loss after aging is even greater. Simple physical mixing cannot achieve uniform and firm loading of nano-tungsten disulfide on the silicon dioxide surface and the interfacial bridging effect of the organosilicon network, which proves the necessity of constructing a core-shell structure.

[0033] Comparative Example 2, where ordinary silica was used to completely replace the functional filler of this invention, exhibited the worst performance. It had the lowest tensile strength and elongation at break, the worst abrasion resistance, and the most severe performance degradation after thermal aging. Traditional fillers cannot provide the synergistic gains of high strength, high abrasion resistance, and excellent thermal stability brought about by the core-shell structure and modified nanosheets, highlighting the technological advancement and irreplaceability of the filler system of this invention.

[0034] Comparative Example 3 exhibited significantly worse abrasion resistance and tensile strength than Example 1; the unmodified boron nitride nanosheets showed poor dispersion and weak interfacial bonding in the rubber matrix, preventing them from fully realizing their reinforcing and abrasion resistance potential. This demonstrates the crucial role of surface-grafted vinyl modification of boron nitride to enable its participation in the vulcanization crosslinking network.

[0035] In Comparative Example 4, the tensile strength and wear resistance decreased significantly and the thermal aging performance deteriorated when only the core-shell filler was missing. The use of modified boron nitride nanosheets and carbon black alone could not compensate for the core contribution of high strength, high wear resistance and thermal stability brought by the core-shell filler, proving that the core-shell composite filler is the first key element of the present invention.

[0036] Comparative Example 5 serves as a control compared to Comparative Example 4. Although the core-shell filler was retained and the strength was acceptable, the wear resistance was still inferior to that of Example 1, and the strength increase after thermal aging was relatively low. The modified boron nitride nanosheets played a key synergistic role, especially in further improving the ultimate wear resistance and dimensional stability of the composite material at high temperatures, which demonstrates its value as the second key element.

[0037] Example 4 showed a significant decline in performance, but was still superior to traditional fillers. Compared to Example 1, its wear resistance was significantly worse, and its tensile strength decreased; however, it was still superior to Comparative Examples 2 and 4, demonstrating that even without WS2, the porous SiO2 core@organosiloxane shell structure itself still possesses superior reinforcing and thermal stabilizing effects compared to traditional fillers. This example directly and powerfully demonstrates the indispensability of nano-tungsten disulfide as a solid lubricant embedded in the shell layer for achieving the core wear-resistant advantage of this invention. Its wear mechanism shifts from pure abrasive wear to a gentler frictional wear.

[0038] This invention innovatively designs and prepares a composite filler with a porous nano-silica core and an organosilicon hybrid network coated with nano-tungsten disulfide as the shell. This filler is then combined with modified boron nitride nanosheets grafted with vinyl groups. Under a specific rubber matrix and peroxide vulcanization system, a significant synergistic enhancement effect is achieved. This technical solution successfully solves the technical challenge of balancing high strength, high wear resistance, low compression set, and excellent heat aging resistance in traditional rubber sealing strips. Examples 1-3 demonstrate the stable and excellent performance of this solution. Comparative Examples 1-5, on the other hand, systematically demonstrate from the opposite perspective that the absence of a core-shell structure and key components leads to significant performance degradation.

[0039] 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 rubber sealing strip, characterized in that, The product comprises, by weight, the following components: 50-70 parts of EPDM rubber, 30-50 parts of nitrile rubber, 15-25 parts of core-shell composite filler, 5-10 parts of carbon black, 3-8 parts of modified boron nitride nanosheets, 1.5-3 parts of peroxide vulcanizing agent, 1-2 parts of crosslinking agent, 1-2 parts of antioxidant, and 1-3 parts of lubricant; wherein the core-shell composite filler is a composite material with porous nano-silica as the core, an organosiloxane network, and embedded nano-tungsten disulfide as the shell.

2. The rubber sealing strip according to claim 1, characterized in that, The preparation method of the core-shell structured composite filler includes the following steps: (1) Disperse porous nano-silica in an ethanol-water mixed solvent and sonicate to form a uniform suspension; (2) Add the silane coupling agent containing amino or epoxy groups and the nano tungsten disulfide sheet dispersion to the suspension in step (1), and stir and react for 4-8 hours under pH 4-5 and 60-80℃ conditions to hydrolyze and condense the silane coupling agent, forming an organosilicon hybrid network shell coating nano tungsten disulfide on the surface and in the pores of silica. (3) The product obtained in step (2) is separated, washed, and vacuum dried at 80-100℃. After grinding, the core-shell structure composite filler is obtained.

3. A rubber sealing strip according to claim 2, characterized in that, In step (1), the volume ratio of ethanol to water in the ethanol-water mixed solvent is 6-10:1; the concentration of the porous nano silica in the suspension is 20-60 g / L.

4. A rubber sealing strip according to claim 2, characterized in that, The silane coupling agent in step (2) is γ-aminopropyltriethoxysilane or γ-(2,3-epoxypropoxy)propyltrimethoxysilane; the thickness of the nano-tungsten disulfide sheets is 5-20 nm, and the sheet diameter is 50-200 nm; the pore size of the porous nano-silica is 5-15 nm, and the specific surface area is 300-600 m². 2 / g.

5. A rubber sealing strip according to claim 2, characterized in that, In step (2), the mass concentration of tungsten disulfide nanosheets in the dispersion is 1-5 g / L; the mass ratio of tungsten disulfide nanosheets to porous nano-silica is 1:5-20; the amount of silane coupling agent is 2%-8% of the total mass of porous nano-silica and tungsten disulfide nanosheets; and the reagent used to adjust the pH is an acetate-sodium acetate buffer solution or dilute nitric acid.

6. A rubber sealing strip according to claim 1, characterized in that, In step (3), the modified boron nitride nanosheets are prepared by dispersing boron nitride nanosheets in an ethanol solution containing silane coupling agent KH-570, refluxing at 70-80℃ for 6-12 hours, centrifuging, washing and drying after reaction to obtain modified boron nitride nanosheets with vinyl groups grafted on the surface.

7. A rubber sealing strip according to claim 6, characterized in that, The mass concentration of KH-570 silane coupling agent in the ethanol solution is 5%-15%; the mass ratio of boron nitride nanosheets to KH-570 silane coupling agent is 5-10:1; and the dispersion concentration of boron nitride nanosheets in the ethanol solution is 10-30 g / L.

8. A rubber sealing strip according to claim 1, characterized in that, The peroxide vulcanizing agent is at least one of dicumyl peroxide and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; the co-crosslinking agent is triallyl isocyanurate or trimethylolpropane trimethacrylate.

9. A method for preparing a rubber sealing strip, used to prepare a rubber sealing strip according to any one of claims 1 to 8, characterized in that the step... include: S1. First stage of mixing: Put EPDM rubber and nitrile rubber into an internal mixer and plasticize at 70-90℃ for 1-2 minutes; add antioxidant and lubricant in sequence and mix for 3-5 minutes; then add core-shell structured composite filler and modified boron nitride nanosheets and mix for 2-4 minutes; discharge the rubber to obtain masterbatch and cool and stand; S2. Two-stage mixing: Put the masterbatch back into the internal mixer or open mill, add carbon black, peroxide vulcanizing agent and crosslinking agent, and mix evenly at 60-80℃ to obtain the final compound. S3. Extrusion and vulcanization: The final rubber compound is fed into an extruder and extruded through a die to form a sealing strip preform; the preform is then sent to a vulcanizing tank or a continuous vulcanization production line for vulcanization to obtain the rubber sealing strip.

10. A method for preparing a rubber sealing strip according to claim 9, characterized in that, The vulcanization is carried out at 160-180℃ and 8-15 MPa pressure for 10-20 minutes.

Images