Ethylene-propylene-diene monomer rubber sealing strip and preparation method thereof

Abstract

The invention discloses an ethylene propylene diene monomer rubber sealing strip and a preparation method thereof, and relates to the technical field of sealing materials. The EPDM rubber sealing strip provided by the invention at least comprises the following raw materials in parts by mass: 100 parts of EPDM rubber; 40 to 70 parts of a carbon black-white carbon black coated reinforcing agent; 5 to 20 parts of zinc methacrylate; 5 to 15 parts of double modified montmorillonite; 3 to 10 parts of modified lignocellulose; 1-3 parts of a silane coupling agent; 3-5 parts of zinc oxide; 1-2 parts of stearic acid; 10-25 parts of a plasticizer; 1-3 parts of a vulcanizing agent; and 1.5-4 parts of an accelerant. The obtained EPDM rubber sealing strip has the advantages of being excellent in mechanical property, high in size stability, low in compression permanent deformation rate and good in sound insulation and flame retardant effect.

Description

Technical Field

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

[0002] As people's living standards improve, the demand for comfort and safety in automobiles is also increasing. Vehicle sealing performance has become a key focus and a crucial factor in judging overall vehicle quality. Automotive sealing strips are one of the important components determining this indicator. They are widely used in various parts of the vehicle, including front and rear windshields, doors, windows, engine compartment, and trunk, filling gaps between body components. They provide functions such as shock absorption, waterproofing, dustproofing, sound insulation, and decoration, protecting drivers, passengers, and the entire vehicle. There are many types of automotive sealing strips. Classified by installation location (component), they include engine compartment sealing strips, front and rear windshield sealing strips, door frame sealing strips, door sealing strips, door glass guide channel sealing strips, lower door dustproof strips, inner and outer door sill sealing strips, side window sealing strips, sunroof sealing strips, roof sealing strips, and trunk (luggage) sealing strips.

[0003] Ethylene propylene diene monomer (EPDM) rubber, due to its saturated main chain structure, possesses excellent weather resistance, ozone resistance, and heat aging resistance, making it the preferred material for manufacturing automotive sealing strips. As the automotive industry moves towards high performance, lightweight design, and enhanced comfort, more stringent requirements are being placed on the comprehensive performance of sealing strips. Ideal automotive sealing strips not only need basic waterproof and dustproof functions but also need to maintain stable sealing pressure (i.e., low compression set) during long-term use, while also possessing good sound insulation and noise reduction properties and a certain degree of flame retardancy to improve the driving experience and overall vehicle safety. Therefore, how to develop a high-toughness, low-deformation, vibration-damping, sound-insulating, and flame-retardant EPDM automotive sealing strip has become an urgent problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a EPDM rubber sealing strip and its preparation method, thereby solving the following technical problems: Existing EPDM rubber sealing strips suffer from weak mechanical properties, poor sound insulation and flame retardant effects, and poor dimensional stability.

[0005] The objective of this invention can be achieved through the following technical solutions: A EPDM rubber sealing strip comprises at least the following parts by weight of raw materials: 100 parts of EPDM rubber; 40-70 parts of carbon black-silica coating reinforcing agent; 5-20 parts of zinc methacrylate; 5-15 parts of double-modified montmorillonite; 3-10 parts of modified lignocellulose; 1-3 parts of silane coupling agent; 3-5 parts of zinc oxide; 1-2 parts of stearic acid; 10-25 parts of plasticizer; 1-3 parts of vulcanizing agent; 1.5-4 parts of accelerator. The dual-modified montmorillonite is montmorillonite synergistically modified with hexadecyltrimethylammonium bromide and γ-methacryloyloxypropyltrimethoxysilane; The modified lignocellulose is a lignocellulose fiber that has been surface-grafted with γ-methacryloxypropyltrimethoxysilane.

[0006] As a further aspect of the present invention, the preparation method of the dual-modified montmorillonite includes at least the following preparation steps: Montmorillonite was dispersed in deionized water, the pH was adjusted to neutral, an aqueous solution of hexadecyltrimethylammonium bromide was added, and the mixture was reacted at 60-80℃ for 2-4 hours. The mixture was then filtered, washed, and dried to obtain intercalated montmorillonite. The intercalated montmorillonite was dispersed in anhydrous ethanol, and a hydrolysate of γ-methacryloxypropyltrimethoxysilane was added. The pH was adjusted to 4-5, and the mixture was reacted at 60-80℃ for 2-3 hours. The mixture was then washed, dried, and ground to obtain the double-modified montmorillonite.

[0007] As a further aspect of the present invention: the mass ratio of the montmorillonite, the hexadecyltrimethylammonium bromide and the γ-methacryloyloxypropyltrimethoxysilane is 1:0.1-0.3:0.05-0.15.

[0008] As a further aspect of the present invention, the method for preparing the modified lignocellulose includes at least the following preparation steps: Ammonia, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane were added to anhydrous ethanol and stirred until homogeneous. Then, lignocellulose was added and the mixture was reacted at 30-50℃ for 2-6 hours under ultrasonic conditions. The mixture was then washed and dried to obtain modified lignocellulose.

[0009] As a further aspect of the present invention: the length of the lignocellulose is 50-200 μm and the aspect ratio is 10-30.

[0010] As a further aspect of the present invention: the mass ratio of the lignocellulose, the ammonia, the tetraethyl orthosilicate and the γ-methacryloyloxypropyltrimethoxysilane is 1:0.5-1.5:0.5-1.5:0.2-0.8, and the concentration of the ammonia is 25-28 wt%.

[0011] As a further aspect of the present invention, the preparation method of the carbon black-silica coated reinforcing agent includes at least the following preparation steps: The pH of the sodium silicate solution was adjusted to 7-8, and after standing and gelling, seed crystals were obtained. The seed crystals were added to a dilute sodium silicate solution, and the pH was adjusted to neutral under water bath heating. Hexadecyltrimethylammonium bromide was added, dissolved, and then carbon black was added and stirred. After reaction, the mixture was aged, filtered, washed with water and alcohol, filtered again, and dried to obtain a carbon black-silica coating reinforcing agent.

[0012] As a further aspect of the present invention: the mass percentage of silica in the carbon black-silica coating reinforcing agent is 20-40%.

[0013] As a further aspect of the present invention: the plasticizer is at least one of paraffin oil, naphthenic oil or dioctyl sebacate, the silane coupling agent is at least one of γ-methacryloyloxypropyltrimethoxysilane or vinyltriethoxysilane, the accelerator is at least one of accelerator CZ, accelerator M or accelerator DM, and the vulcanizing agent is at least one of dicumyl peroxide or sulfur.

[0014] A method for preparing an EPDM rubber sealing strip as described in any one of the above claims includes at least the following preparation steps: After plasticizing EPDM rubber in a mixer, zinc oxide, stearic acid, part of carbon black-silica coating reinforcing agent, double-modified montmorillonite and modified lignocellulose are added and mixed and discharged. Then, the remaining carbon black-silica coating reinforcing agent, zinc methacrylate, plasticizer and silane coupling agent are added and mixed and discharged to obtain masterbatch. The masterbatch is added to a two-roll mill, along with a vulcanizing agent and an accelerator. The mixture is then extruded and vulcanized to obtain an EPDM rubber sealing strip.

[0015] The beneficial effects of this invention are: This invention provides a EPDM rubber sealing strip and its preparation method. The EPDM rubber sealing strip comprises EPDM rubber, carbon black-silica coating reinforcing agent, zinc methacrylate, double-modified montmorillonite, modified lignocellulose, and other raw materials. EPDM rubber serves as the matrix to ensure basic weather resistance and insulation performance; the coating reinforcing agent achieves efficient reinforcement; zinc methacrylate optimizes crosslinking and mechanical properties; double-modified montmorillonite enhances barrier and deformation resistance; modified lignocellulose balances reinforcement and environmental friendliness; silane coupling agent, zinc oxide, stearic acid, and other additives optimize interfacial bonding and vulcanization molding effects; plasticizer improves processing fluidity; and vulcanizing agent and accelerator ensure vulcanization crosslinking efficiency. The prepared EPDM rubber sealing strip possesses excellent mechanical strength, weather resistance, creep resistance, wear resistance, and sealing stability, with comprehensive performance far exceeding that of traditional sealing strips. It can be widely used in automotive body sealing, energy-saving building doors and windows, rail transit carriages, and high-end machinery equipment sealing, among other fields.

[0016] The carbon black-silica coated reinforcing agent prepared in this invention achieves uniform coating of silica on the carbon black surface through sodium silicate gel coating and surface modification. This retains the high-strength reinforcing properties of carbon black while also possessing the aging resistance and low heat generation advantages of silica, significantly improving the dispersibility and interfacial compatibility of fillers in the rubber matrix and reducing filler agglomeration defects. This invention also incorporates zinc methacrylate for synergistic reinforcement. The nano-ionic clusters formed by the in-situ polymerization of zinc methacrylate during vulcanization not only constitute a high-strength ionic cross-linking network themselves but also interact with the active groups on the surface of the carbon black-silica reinforcing agent through the bridging effect of silane coupling agents. This tightly combines the rigid reinforcing network with the reversible ionic network, significantly improving the tensile strength, tear strength, and other mechanical properties of the sealing strip. It also optimizes the elastic recovery and compression set resistance of the sealing strip, while reducing the processing viscosity of the rubber compound and improving its processability. This avoids the performance shortcomings caused by single-filler reinforcement, achieving a dual improvement in both mechanical and processing properties.

[0017] This invention further optimizes the overall performance of the material by adding double-modified montmorillonite and modified lignocellulose. The prepared double-modified montmorillonite is first expanded by hexadecyltrimethylammonium bromide intercalation to increase the interlayer spacing, and then surface-grafted with γ-methacryloyloxypropyltrimethoxysilane. This significantly improves the compatibility and interlayer peelability of montmorillonite with the rubber matrix, ensuring uniform dispersion in the rubber compound and effectively enhancing the barrier properties, creep resistance, and aging resistance of the sealing strip. Furthermore, the selection of γ-methacryloyloxypropyltrimethoxysilane as the grafting modifier allows the unsaturated double bonds on the grafting modifier to participate in the vulcanization process. The cross-linking reaction produces grafting or cross-linking, improving interfacial bonding. Modified lignocellulose undergoes surface grafting modification with the same silane coupling agent, addressing the issues of strong surface polarity and poor compatibility with the rubber matrix in natural lignocellulose. This optimizes the interfacial bonding between the fiber and the matrix, leveraging the green reinforcing and carbon-reducing effects of lignocellulose while enhancing the wear resistance and dimensional stability of the sealing strip. The dual-modified montmorillonite and modified lignocellulose in the formulation create a multi-dimensional synergistic reinforcing effect. The interpenetrating and overlapping of the sheet-like dual-modified montmorillonite and the fibrous modified lignocellulose further enhance the material's stiffness and dimensional stability. During combustion, the modified lignocellulose, as a high-quality carbon source, preferentially carbonizes, working in conjunction with the migrating dual-modified montmorillonite sheets to form a dense organic-inorganic hybrid carbon layer, significantly improving the flame-retardant performance of the sealing strip. Simultaneously, the multi-scale filler distribution increases interfacial reflection and scattering loss during sound wave propagation within the material, endowing the sealing strip with excellent sound insulation properties. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: The preparation method of double-modified montmorillonite includes the following steps: 100g of sodium montmorillonite was dispersed in 2000mL of deionized water and stirred until homogeneous. The pH was adjusted to 7.0 with 0.1mol / L hydrochloric acid solution to obtain a montmorillonite suspension. 20g of hexadecyltrimethylammonium bromide was dissolved in 500mL of deionized water to obtain an aqueous solution of hexadecyltrimethylammonium bromide. The aqueous solution of hexadecyltrimethylammonium bromide was then added to the montmorillonite suspension. The mixture was heated and stirred in a water bath at 70℃ for 3 hours. After the reaction was completed, the mixture was filtered, washed, dried at 80℃ for 12 hours, and ground through a 200-mesh sieve to obtain intercalated montmorillonite. Add 5g of γ-methacryloxypropyltrimethoxysilane to 100mL of anhydrous ethanol and 5g of deionized water, adjust the pH to 5 with 1mol / L oxalic acid, and hydrolyze for 1h to obtain a hydrolysate of γ-methacryloxypropyltrimethoxysilane. Disperse 80g of the above-mentioned intercalated montmorillonite in 1000mL of anhydrous ethanol, add the above-mentioned hydrolysate of γ-methacryloxypropyltrimethoxysilane, heat and stir in a water bath at 70℃ for 2.5h. After the reaction is completed, filter, wash, dry at 80℃ for 12h, grind through a 200-mesh sieve to obtain double-modified montmorillonite.

[0020] Example 2: The preparation method of modified lignocellulose includes the following steps: 6 mL of 26 wt% ammonia, 6 mL of tetraethyl orthosilicate, and 3 mL of γ-methacryloyloxypropyltrimethoxysilane were sequentially added to 300 mL of anhydrous ethanol and stirred until homogeneous. Then, 60 g of lignocellulose powder (average length 100 μm, aspect ratio 20) was added. The mixture was reacted under ultrasonic conditions in a water bath at 40 °C for 4 h. After the reaction was completed, the mixture was filtered, and the filter cake was washed three times with anhydrous ethanol. The cake was then vacuum dried at 105 °C for 12 h to obtain modified lignocellulose.

[0021] Example 3: The preparation method of carbon black-silica coated reinforcing agent includes the following steps: A 1 mol / L hydrochloric acid solution was slowly added dropwise to a 10 wt% sodium silicate solution, the pH was adjusted to 7.5, and the solution was allowed to stand until gelation occurred to obtain seed crystals. The seed crystals were added to a 5 wt% sodium silicate solution and heated to 80°C in a water bath. 1 mol / L hydrochloric acid solution was added dropwise to adjust the pH to 7.0. 5 g of hexadecyltrimethylammonium bromide was added and stirred until dissolved. Then, 50 g of carbon black (N330) was added, and the mixture was stirred for another 3 hours. After the reaction was complete, the mixture was aged at room temperature for 12 hours, filtered, washed successively with deionized water and anhydrous ethanol, and dried at 80°C. Before use, the mixture was dried at 140°C for 2 hours to remove bound water, yielding a carbon black-silica coated reinforcing agent.

[0022] Example 4: The preparation steps of the EPDM rubber sealing strip are as follows: Preheat the internal mixer to 60°C, add 100 parts by weight of EPDM rubber (Keltan 8550C), and plasticize for 1.5 min. Then add 4 parts by weight of zinc oxide, 1.5 parts by weight of stearic acid, 27.5 parts by weight of carbon black-silica coating reinforcing agent prepared in Example 3, 10 parts by weight of double-modified montmorillonite prepared in Example 1, and 6 parts by weight of modified lignocellulose prepared in Example 2. Mix for 4 min, then heat to 145°C and discharge the glue. Add the remaining 27.5 parts by weight of carbon black-silica coating reinforcing agent, 12 parts by weight of zinc methacrylate, 18 parts by weight of plasticizer paraffin oil, and 2 parts by weight of silane coupling agent γ-methacryloyloxypropyltrimethoxysilane. Mix for 3 min, then heat to 135°C and discharge the glue to obtain the masterbatch. The above-mentioned masterbatch was added to an open mill, along with 2 parts by weight of sulfur vulcanizing agent, 1.7 parts by weight of accelerator CZ, and 0.8 parts by weight of accelerator TMTD. The mixture was passed through a thin mill four times, and then sheeted out. The sheet was then extruded into an extruder. The temperatures of each section of the extruder were set as follows: 55°C for the feeding section, 65°C for the compression section, 75°C for the metering section, and 85°C for the die head. After extrusion, the sheet was first vulcanized in a microwave vulcanizing chamber with a microwave power of 5kW, a temperature of 200°C, and a time of 4 minutes. Then, it was vulcanized in a hot air vulcanizing channel for a second stage of vulcanization with a temperature of 220°C and a time of 8 minutes. Finally, the sheet was cooled, drawn, and cut to obtain an EPDM rubber sealing strip.

[0023] Example 5: The preparation steps of the EPDM rubber sealing strip are as follows: Preheat the internal mixer to 60°C, add 100 parts by weight of EPDM rubber (Keltan 8550C), and plasticize for 1.5 min. Then add 5 parts by weight of zinc oxide, 1.5 parts by weight of stearic acid, 25 parts by weight of carbon black-silica coating reinforcing agent prepared in Example 3, 14 parts by weight of double-modified montmorillonite prepared in Example 1, and 5 parts by weight of modified lignocellulose prepared in Example 2. Mix for 4 min, then heat to 148°C and discharge the glue. Add the remaining 25 parts by weight of carbon black-silica coating reinforcing agent, 18 parts by weight of zinc methacrylate, 15 parts by weight of plasticizer paraffin oil, and 2.5 parts by weight of silane coupling agent γ-methacryloyloxypropyltrimethoxysilane. Mix for 3 min, then heat to 138°C and discharge the glue to obtain the masterbatch. The above-mentioned masterbatch was added to an open mill, along with 2.2 parts by weight of sulfur vulcanizing agent, 1.8 parts by weight of accelerator CZ, and 0.9 parts by weight of accelerator TMTD. The mixture was passed through a thin mill four times, and then sheeted out. The sheet was then extruded into an extruder. The temperatures of each section of the extruder were set as follows: 55°C for the feeding section, 65°C for the compression section, 75°C for the metering section, and 85°C for the die head. After extrusion, the sheet was first vulcanized in a microwave vulcanizing chamber with a microwave power of 5kW, a temperature of 200°C, and a time of 4 minutes. Then, it was vulcanized in a hot air vulcanizing channel for a second stage of vulcanization with a temperature of 220°C and a time of 8 minutes. Finally, the sheet was cooled, drawn, and cut to obtain an EPDM rubber sealing strip.

[0024] Example 6: The preparation steps of the EPDM rubber sealing strip are as follows: Preheat the internal mixer to 60°C, add 100 parts by weight of EPDM rubber (Keltan 8550C), and masticate for 1.5 min. Then add 4 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 32.5 parts by weight of carbon black-silica coating reinforcing agent prepared in Example 3, 8 parts by weight of double-modified montmorillonite prepared in Example 1, and 9 parts by weight of modified lignocellulose prepared in Example 2. After mixing for 4 min, discharge the glue when the temperature is raised to 142°C. Then add the remaining 32.5 parts by weight of carbon black-silica coating reinforcing agent, 8 parts by weight of zinc methacrylate, 22 parts by weight of paraffin oil, and 1.5 parts by weight of silane coupling agent γ-methacryloyloxypropyltrimethoxysilane. Mix for 3 min, discharge the glue when the temperature is raised to 132°C, and obtain the masterbatch. The above-mentioned masterbatch was added to an open mill, along with 1.8 parts by weight of sulfur, 1.5 parts by weight of accelerator CZ, and 0.7 parts by weight of accelerator TMTD. The mixture was passed through a thin mill four times, and then sheeted out. The sheet was then extruded into an extruder. The temperatures of each section of the extruder were set as follows: 55°C for the feeding section, 65°C for the compression section, 75°C for the metering section, and 85°C for the die head. After extrusion, the sheet was first vulcanized in a microwave vulcanizing chamber with a microwave power of 5kW, a temperature of 200°C, and a time of 4 minutes. Then, it was vulcanized in a hot air vulcanizing channel for a second stage of vulcanization with a temperature of 220°C and a time of 8 minutes. Finally, the sheet was cooled, drawn, and cut to obtain an EPDM rubber sealing strip.

[0025] Comparative Example 1: The preparation method of the double-modified montmorillonite includes the following steps: 100g of sodium montmorillonite was dispersed in 2000mL of deionized water and stirred until homogeneous. The pH was adjusted to 7.0 with 0.1mol / L hydrochloric acid solution to obtain a montmorillonite suspension. 20g of hexadecyltrimethylammonium bromide was dissolved in 500mL of deionized water to obtain an aqueous solution of hexadecyltrimethylammonium bromide. The aqueous solution of hexadecyltrimethylammonium bromide was then added to the montmorillonite suspension. The mixture was heated and stirred in a water bath at 70℃ for 3 hours. After the reaction was completed, the mixture was filtered, washed, dried at 80℃ for 12 hours, and ground through a 200-mesh sieve to obtain intercalated montmorillonite. Add 5g of γ-aminopropyltriethoxysilane to 100mL of anhydrous ethanol and 5g of deionized water, adjust the pH to 5 with 1mol / L oxalic acid, and hydrolyze for 1h to obtain a hydrolysate of γ-aminopropyltriethoxysilane. Disperse 80g of the above-mentioned intercalated montmorillonite in 1000mL of anhydrous ethanol, add the above-mentioned hydrolysate of γ-aminopropyltriethoxysilane, and heat and stir the reaction in a water bath at 70℃ for 2.5h. After the reaction is completed, filter, wash, dry at 80℃ for 12h, grind through a 200-mesh sieve to obtain double-modified montmorillonite.

[0026] Compared with Example 4, Comparative Example 2 only replaced the double-modified montmorillonite prepared in Example 1 with the double-modified montmorillonite prepared in Comparative Example 1 in the same mass as that in Example 4. The other components and preparation methods were completely the same as those in Example 4.

[0027] Compared with Example 4, Comparative Example 3 only did not add the modified lignocellulose prepared in Example 2, while the other components and preparation methods were completely the same as in Example 4.

[0028] Compared with Example 4, Comparative Example 4 only replaced the carbon black-silica coating reinforcing agent prepared in Example 3 with the unmodified carbon black in Example 3. The other components and preparation methods were completely the same as those in Example 4.

[0029] Compared with Example 4, Comparative Example 5 only did not add zinc methacrylate; the other components and preparation methods were completely the same as those in Example 4.

[0030] Performance testing Impact strength test: The single-sided notched impact strength of the samples was tested using the cantilever beam impact testing machine selected above. The sample size was set to 65.0mm × 13.5mm × 6.5mm. Before testing, the samples were placed in a 25℃ environment for 1 day. The unmodified and modified sample strips were tested in this environment, and the impact strength values ​​were calculated. The specific calculation formula is set as follows: W = Y / (b × c); In the formula, Y represents the impact energy consumption value in J; b represents the sample width in m; c represents the remaining sample thickness in m; the detection results are shown in Table 1. Tensile strength testing: A universal testing machine was used as the testing instrument, and the experimental operation was carried out according to the operating standard GB / T 1040-92. The tensile speed of the samples was set to 60 mm / min. Tensile strength tests were performed on the sample strips before and after modification in the same constant temperature environment of 25℃, and the tensile strength was calculated using the following formula: β=E MAX / (b×c; In the formula, E MAX denoted by , b represents the maximum tensile force (N); b represents the sample width (m); c represents the remaining sample thickness (m); the test results are shown in Table 1. Shrinkage deformation rate: Tested according to national standard GB / T3903.10. Draw two mutually perpendicular lines along the diagonal on a 20cm×20cm sample, mark a length of 15cm, and record it as L0. Place the sample in an oven at 70℃ for 40min, then let it stand at room temperature for 30min. Measure the length L1 of the two lines. The specific calculation formula is set as follows: S (heat shrinkage deformation rate) = (L1 - L0) / L0 × 100%; In the formula, S represents the thermal shrinkage deformation rate (%); L0 represents the sample length (m); L1 represents the remaining sample length (m); the test results are shown in Table 1. Compression set: The test was conducted according to the national standard HG / T2876-2009. The sample was cut into 25mm×25mm×10mm pieces, and the original thickness d0 was measured. The sample was clamped in a compression mold and placed in a 50℃ oven for 6 hours. After that, it was removed and allowed to cool at room temperature for 30 minutes. The thickness d1 was then measured. The specific calculation formula is set as follows: ε (compression permanent deformation rate) = (d1 - d0) / d0 × 100%; In the formula, ε represents the thermal shrinkage deformation rate (%); L0 represents the sample thickness (m); L1 represents the remaining sample thickness (m); the test results are shown in Table 1. Sound absorption coefficient: The sound absorption performance of the sample was tested using a four-channel digital signal acquisition system. The test was repeated three times and the average value was taken. The sound absorption coefficient in the frequency range of 1600-6300Hz reflects the strength of the sound absorption performance. The test results are shown in Table 1. Vertical flammability test (UL-94): The vertical flammability tester was used to test the test specimens according to GB / T 2408-2008 "Test of flammability of plastics - Horizontal and Vertical Methods". The specimen size was (125±0.5) mm × (13±0.5) mm × (3±0.5) mm. The test results are shown in Table 1. Table 1: Statistical Table of Performance Test Data for Specimens from Examples 4-6 and Comparative Examples 2-5

[0031] As shown in Table 1, the EPDM rubber sealing strip prepared by the present invention has the advantages of excellent mechanical properties, strong dimensional stability, low compression set, and good sound insulation and flame retardant effect. In Comparative Example 2, the added double-modified montmorillonite was hexadecyltrimethylammonium bromide and γ-aminopropyltriethoxysilane modified montmorillonite. The interfacial bonding force of the montmorillonite decreased, resulting in a significant reduction in the tensile strength and impact strength of the obtained sealing strip, an increase in the compression set, and a simultaneous decline in dimensional stability, sound insulation, and flame retardant performance. In Comparative Example 3, no modified lignocellulose was added, resulting in the absence of fiber reinforcing components. The obtained sealing strip had impaired toughness and sound absorption performance, and lacked an effective carbon source during combustion, leading to a decrease in flame retardancy. The thermal shrinkage deformation rate and compression set also increased significantly. In Comparative Example 4, the added carbon black was not modified, resulting in poor carbon black dispersion. The obtained sealing strip exhibited a significant decrease in mechanical properties and deformation resistance. The absence of silica also caused a simultaneous deterioration in the material's sound insulation, flame retardant, and aging resistance. In Comparative Example 5, no zinc methacrylate was added, resulting in the absence of an ionic crosslinking network. The obtained sealing strip exhibited decreased mechanical strength and elastic recovery, and an increased compression set.

[0032] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0033] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A EPDM rubber sealing strip, characterized in that, It shall include at least the following parts by weight of raw materials: 100 parts of EPDM rubber; 40-70 parts of carbon black-silica coating reinforcing agent; 5-20 parts of zinc methacrylate; 5-15 parts of double-modified montmorillonite; 3-10 parts of modified lignocellulose; 1-3 parts of silane coupling agent; 3-5 parts of zinc oxide; 1-2 parts of stearic acid; 10-25 parts of plasticizer; 1-3 parts of vulcanizing agent; 1.5-4 parts of accelerator. The dual-modified montmorillonite is montmorillonite synergistically modified with hexadecyltrimethylammonium bromide and γ-methacryloyloxypropyltrimethoxysilane; The modified lignocellulose is a lignocellulose fiber that has been surface-grafted with γ-methacryloxypropyltrimethoxysilane.

2. The EPDM rubber sealing strip according to claim 1, characterized in that, The preparation method of the double-modified montmorillonite includes at least the following preparation steps: Montmorillonite was dispersed in deionized water, the pH was adjusted to neutral, an aqueous solution of hexadecyltrimethylammonium bromide was added, and the mixture was reacted at 60-80℃ for 2-4 hours. The mixture was then filtered, washed, and dried to obtain intercalated montmorillonite. The intercalated montmorillonite was dispersed in anhydrous ethanol, and a hydrolysate of γ-methacryloxypropyltrimethoxysilane was added. The pH was adjusted to 4-5, and the mixture was reacted at 60-80℃ for 2-3 hours. The mixture was then washed, dried, and ground to obtain the double-modified montmorillonite.

3. The EPDM rubber sealing strip according to claim 2, characterized in that, The mass ratio of the montmorillonite, the hexadecyltrimethylammonium bromide, and the γ-methacryloyloxypropyltrimethoxysilane is 1:0.1-0.3:0.05-0.

15.

4. The EPDM rubber sealing strip according to claim 1, characterized in that, The method for preparing the modified lignocellulose includes at least the following preparation steps: Ammonia, tetraethyl orthosilicate, and γ-methacryloyloxypropyltrimethoxysilane were added to anhydrous ethanol and stirred until homogeneous. Then, lignocellulose was added and the mixture was reacted at 30-50℃ for 2-6 hours under ultrasonic conditions. The mixture was then washed and dried to obtain modified lignocellulose.

5. The EPDM rubber sealing strip according to claim 4, characterized in that, The lignocellulose has a length of 50-200 μm and an aspect ratio of 10-30.

6. The EPDM rubber sealing strip according to claim 4, characterized in that, The mass ratio of the lignocellulose, the ammonia, the tetraethyl orthosilicate, and the γ-methacryloyloxypropyltrimethoxysilane is 1:0.5-1.5:0.5-1.5:0.2-0.8, and the concentration of the ammonia is 25-28 wt%.

7. The EPDM rubber sealing strip according to claim 1, characterized in that, The preparation method of the carbon black-silica coated reinforcing agent includes at least the following preparation steps: The pH of the sodium silicate solution was adjusted to 7-8, and after standing and gelling, seed crystals were obtained. The seed crystals were added to a dilute sodium silicate solution, and the pH was adjusted to neutral under water bath heating. Hexadecyltrimethylammonium bromide was added, dissolved, and then carbon black was added and stirred. After reaction, the mixture was aged, filtered, washed with water and alcohol, filtered again, and dried to obtain a carbon black-silica coating reinforcing agent.

8. The EPDM rubber sealing strip according to claim 7, characterized in that, The mass percentage of silica in the carbon black-silica coating reinforcing agent is 20-40%.

9. The EPDM rubber sealing strip according to claim 1, characterized in that, The plasticizer is at least one of paraffin oil, naphthenic oil, or dioctyl sebacate; the silane coupling agent is at least one of γ-methacryloxypropyltrimethoxysilane or vinyltriethoxysilane; the accelerator is at least one of accelerator CZ, accelerator M, or accelerator DM; and the vulcanizing agent is at least one of dicumyl peroxide or sulfur.

10. A method for preparing a EPDM rubber sealing strip according to any one of claims 1-9, characterized in that, It includes at least the following preparation steps: After plasticizing EPDM rubber in a mixer, zinc oxide, stearic acid, part of carbon black-silica coating reinforcing agent, double-modified montmorillonite and modified lignocellulose are added and mixed and discharged. Then, the remaining carbon black-silica coating reinforcing agent, zinc methacrylate, plasticizer and silane coupling agent are added and mixed and discharged to obtain masterbatch. The masterbatch is added to a two-roll mill, along with a vulcanizing agent and an accelerator. The mixture is then extruded and vulcanized to obtain an EPDM rubber sealing strip.

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