A high-performance EPDM rubber foam material and its preparation method

Abstract

This invention discloses a EPDM (ethylene propylene diene monomer) foam material based on modified red brick powder and its preparation method, belonging to the field of polymer composite materials technology. This invention improves the dispersibility, compatibility, and mechanical reinforcement effect of red brick powder in an EPDM matrix by surface modification, then uniformly disperses it in the EPDM matrix. Through optimized foaming process, high strength, low density, and excellent cell structure are achieved in the foam material. The EPDM foam material of this invention possesses excellent mechanical properties, flame retardancy, and cell structure, making it suitable for sealing, heat insulation, and vibration damping applications in the automotive, construction, and electronics industries.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, specifically relating to an ethylene propylene diene monomer (EPDM) foam material based on modified red brick powder and its preparation method. This invention improves the dispersibility, compatibility, and reinforcing effect of red brick powder in an EPDM matrix through multiple modifications, thereby optimizing the mechanical properties, flame retardancy, cell structure, and wear resistance of the EPDM foam material. This makes it widely applicable to high-performance rubber products such as automotive seals, rail transit gaskets, industrial cushioning materials, shoe soles, and shock-absorbing rubber. Background Technology

[0002] Ethylene propylene diene monomer (EPDM) rubber is widely used in automotive seals, rail transit gaskets, shock-absorbing materials, industrial cushioning materials, and shoe soles due to its excellent weather resistance, heat resistance, chemical corrosion resistance, and elasticity. However, traditional EPDM foam materials still have some problems: due to the molecular structure of EPDM itself, it is prone to uneven cell structure and reduced strength after foaming, resulting in reduced wear resistance, tear strength, and service life; at the same time, EPDM is mainly composed of hydrocarbon elements, and its oxygen index is low, making it flammable and difficult to meet the requirements of some high safety standards (such as rail transit and building sealing); in addition, traditional inorganic fillers (such as carbon black and calcium carbonate) are prone to agglomeration in the rubber matrix, resulting in uneven internal stress distribution and affecting the final mechanical properties and dimensional stability.

[0003] To address the aforementioned issues, researchers have recently explored the use of nanofillers, functionalized fillers, and optimized foaming processes to improve the overall performance of EPDM foam materials. Among these efforts, the high-value utilization of construction waste has become a research hotspot. Red brick powder (MBP) is a common construction waste, primarily composed of silicates, alumina, and iron oxide, possessing certain mechanical reinforcing and filling properties. However, unmodified red brick powder exhibits low surface activity and poor compatibility with EPDM; direct addition can degrade material performance. Therefore, effectively functionalizing red brick powder to achieve mechanical reinforcement, flame retardant modification, and cell control, while simultaneously optimizing the performance of EPDM foam materials, has become a crucial research direction in this field.

[0004] This invention employs multiple modification techniques—silane coupling agent modification, polydopamine (PDA) coating, and layered double hydroxide (LDH) composite modification—to impart higher compatibility and functionality to red brick powder. This allows it to disperse uniformly in EPDM foam materials and significantly improves the material's mechanical properties, flame retardant properties, and cell structure stability, thereby expanding its applications in high-performance seals, rail transportation, and industrial vibration damping materials. Summary of the Invention

[0005] This invention provides a high-performance ethylene propylene diene monomer (EPDM) foam material based on modified red brick powder and its preparation method, aiming to improve the mechanical properties, flame retardant properties, cell structure stability and wear resistance of EPDM foam material, and expand its application in high-performance rubber products such as automobiles, rail transportation, and industrial cushioning materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A high-performance EPDM rubber foam material based on modified red brick powder is prepared from the following raw materials in parts by weight:

[0008] 100 parts of EPDM rubber

[0009] carbon black 10-40 servings

[0010] 40 parts of modified red brick powder

[0011] 30-50 parts of light calcium carbonate

[0012] 10-20 parts paraffin oil

[0013] 5-15 parts zinc oxide

[0014] Vulcanizing agent 0.5-3 parts,

[0015] Accelerator 0.5-2 parts,

[0016] 1-5 parts stearic acid

[0017] Lubricant 0.5-3 parts,

[0018] 5-15 parts foaming agent.

[0019] In this invention, the ethylene propylene diene monomer (EPDM) rubber can be selected from high-strength, high-resistance EPDM materials, including ExxonMobil Vistalon 7500, Dow Nordel IP4820, Lanxess Keltan 6950, and Kumho KEP270 from South Korea. These EPDM materials have a high ethylene content (50%–70%), providing higher crystallinity and mechanical strength, resulting in superior performance in applications requiring high loads, abrasion resistance, and tear resistance. Keltan 6950, in particular, has a high crosslinking density and good dynamic mechanical properties, making it suitable for applications such as gaskets, shock-absorbing components, and industrial cushioning materials.

[0020] In this invention, the BET specific surface area of ​​the carbon black is 60-120 m². 2 / g, with a particle size of 20-40nm, ensuring the stability of the material in high-load applications. The carbon black used is Cabot Vulcan N330 and Degussa Printex G, among which N330 has the characteristics of high structure and high reinforcement, which can effectively improve the wear resistance, tear strength and thermal conductivity of EPDM foam materials.

[0021] In this invention, the paraffin oil can be selected from Chevron Paralux 6001, Sunpar 150, or NYNASNytex 840. These high-viscosity mineral oils can improve the flowability of EPDM composite materials, optimize filler dispersibility, and enhance the anti-aging properties of the final product. The kinematic viscosity of the paraffin oil at 40°C is controlled at 20-60 cSt to ensure good plasticity during processing.

[0022] In this invention, zinc oxide (ZnO) is used as a vulcanization activator and anti-aging agent to optimize the crosslinking structure of EPDM and improve the weather resistance and fatigue resistance of the material.

[0023] In this invention, the vulcanizing agent is selected from at least one of sulfur and BIBP.

[0024] In this invention, the accelerator is selected from at least one of zinc dibenzyl dithiocarbamate (ZBEC), tetrabenzyl thiuramized disulfide (TBZTD), and zinc diethyl dithiocarbamate (ZDEC). TBZTD can increase the crosslinking density and improve the wear resistance and dynamic properties of the material, while ZDEC can optimize processing performance, enabling the material to maintain good flexibility during high-temperature vulcanization.

[0025] In this invention, the stearic acid is used to improve the processing properties of rubber and enhance the dispersibility of fillers.

[0026] In this invention, the lubricant is polyethylene glycol.

[0027] In this invention, the foaming agent is selected from at least one of 4,4'-oxobis(benzenesulfonyl hydrazine) (OBSH) and azodicarbonamide (AC). A combination of OBSH and AC is preferred to optimize the foaming rate, improve cell stability, and reduce cell collapse.

[0028] In this invention, the modified red brick powder is made by functionalizing waste red brick powder from construction to improve its dispersibility and compatibility in an EPDM matrix. The specific steps are as follows:

[0029] (a) Acid treatment and high-temperature calcination: Red brick powder (MBP) was added to a 3% hydrochloric acid solution and stirred for 30 minutes. After washing with water to remove impurities, it was calcined at 500-800℃ for 2 hours, then washed with water, filtered, and dried at 100℃ for 4 hours to obtain porous red brick powder (P-MBP) with a large specific surface area.

[0030] (b) Silane coupling modification: Take porous red brick powder, add it to anhydrous ethanol, add silane coupling agent Si-69, stir at 80°C for 1-2 hours, filter, and obtain silane-modified red brick powder (Si-MBP).

[0031] (c) Polydopamine (PDA) coating: The obtained silane-modified red brick powder was added to a Tris-HCl buffer solution at pH=8.5, and a dopamine (DA) solution of 2 mg / mL was added. The mixture was stirred for 12 hours to allow dopamine to self-polymerize and coat the surface of the red brick powder, thus obtaining red brick powder coated with polydopamine (PDA-Si-MBP).

[0032] (d) Layered double hydroxide (LDH) composite modification: Take red brick powder coated with polydopamine, add it to MgAI-LDH suspension with a mass concentration of 2-3%, disperse it ultrasonically for 20 minutes, filter it, and vacuum dry it at 80℃ for 4 hours to obtain the modified red brick powder (LDH-PDA-Si-MBP).

[0033] The red brick powder in step (a) has a BET specific surface area of ​​30-80 m² / g and a particle size controlled at 20-50 μm. It has a high reinforcing ability and can improve the wear resistance, tear strength and dimensional stability of the material.

[0034] The mass ratio of porous red brick powder to silane coupling agent Si-69 used in step (b) is 10:1.

[0035] The amount of dopamine solution used in step (c) is calculated based on adding 10 mL per gram of silane-modified red brick powder.

[0036] In step (d), the amount of MgAl-LDH suspension used is calculated based on adding 3 mL of red brick powder coated with polydopamine per gram.

[0037] This invention enhances the filling capacity and load-bearing capacity of waste red brick powder through acid treatment and high-temperature calcination. It improves the interfacial bonding between P-MBP and EPDM by using a coupling agent, thereby enhancing the dispersibility and mechanical reinforcement of the filler in the rubber matrix. Utilizing the adhesive properties of PDA, a uniform functionalized coating is formed on the Si-MBP surface, improving the uniform dispersion and interfacial compatibility of the filler, thus enhancing the tensile strength, abrasion resistance, and tear strength of the material. Loading layered double hydroxide (LDH) nanosheets onto the PDA-coated filler surface optimizes the gas release rate, synchronizing the foaming process with vulcanization, improving cell uniformity, and reducing dimensional shrinkage, thus improving the flame retardancy, thermal stability, and oxidation resistance of the material.

[0038] The preparation method of the high-performance EPDM rubber foam material includes the following steps:

[0039] 1) First, vacuum dry the modified red brick powder at 80-120℃ for 2-4 hours to remove adsorbed moisture, which will help improve its dispersibility in the EPDM matrix;

[0040] 2) Place EPDM in a two-roll mill or internal mixer and plasticize it at 60-90℃ for 3-5 minutes to achieve a suitable plastic state;

[0041] 3) Add carbon black, light calcium carbonate, zinc oxide, stearic acid, paraffin oil, lubricant and dried modified red brick powder to the masticated EPDM in sequence, and mix at 80-100℃ for 8-12 minutes to make the filler evenly dispersed.

[0042] 4) After the materials are fully mixed, cool to 50-70℃, then add accelerator, vulcanizing agent and foaming agent, and continue to mix at 60-80℃ for 5-8 minutes to ensure uniform reaction;

[0043] 5) Place the compound obtained in step 4) into a two-roll mill for secondary plasticizing and perform multiple opening and closing operations to remove the gas generated during the mixing process and improve the foaming uniformity.

[0044] 6) Place the compound obtained in step 5) into a mold for vulcanization and foaming to obtain the high-performance EPDM rubber foam material.

[0045] Furthermore, in step 5), the temperature of the secondary plasticizing process is 40-60℃, and the time is 10-15 minutes.

[0046] Furthermore, the vulcanization foaming in step 6) is carried out by gradually increasing the temperature at a rate of 2-3 ℃ / min, raising the temperature to 155℃, and holding it at that temperature for 25 minutes to reduce the risk of cell structure collapse.

[0047] Furthermore, the vulcanization process can employ microwave-assisted vulcanization (MW-V) or conventional thermal vulcanization (CV) processes to optimize vulcanization crosslinking efficiency and improve the overall performance of the material.

[0048] The prepared high-performance EPDM rubber foam material can be used in high wear-resistant and antistatic rubber products, and is suitable for tires, shoe soles, conveyor belts, sealing rings and rail transportation.

[0049] The beneficial effects of this invention are as follows:

[0050] (1) Improve mechanical properties and extend the service life of materials: PDA functionalization modification of red brick powder can enhance the interfacial bonding force between it and EPDM, significantly improve the tensile strength, tear strength and elongation at break of the material, improve wear resistance and fatigue resistance, making it more suitable for high wear resistance and impact resistance applications (such as tires, conveyor belts and shoe soles); at the same time, its uniform dispersion in EPDM is also improved, which can make the material less prone to cracking under long-term stress and extend the service life of the product.

[0051] (2) Optimize flame retardant properties and improve material safety: The intercalation and synergistic flame retardant effect of LDH sheets introduced into the modified red brick powder in the EPDM matrix can effectively improve the oxygen index (LOI), reduce the burning rate of the material, and improve its fire resistance. In applications such as rail transit and building sealing, reducing the heat release rate (HRR) can effectively reduce heat accumulation during a fire and improve the flame retardant rating of the material.

[0052] (3) Optimize the cell structure and improve dimensional stability: The use of porous red brick powder can improve the foam structure, make the cell distribution uniform, avoid collapse, and improve the resilience and dimensional stability of the material, which is suitable for high-precision seals and cushioning materials. The exhaust optimization and secondary vulcanization process can further stabilize the cell structure, so that the material can maintain good elasticity and density stability after being under pressure and used for a long time. Detailed Implementation

[0053] A high-performance EPDM rubber foam material based on modified red brick powder is prepared from the following raw materials in parts by weight:

[0054] 100 parts of EPDM rubber

[0055] carbon black 10-40 servings

[0056] 40 parts of modified red brick powder

[0057] 30-50 parts of light calcium carbonate

[0058] 10-20 parts paraffin oil

[0059] 5-15 parts zinc oxide

[0060] Vulcanizing agent 0.5-3 parts,

[0061] Accelerator 0.5-2 parts,

[0062] 1-5 parts stearic acid

[0063] Lubricant 0.5-3 parts,

[0064] 5-15 parts foaming agent.

[0065] The vulcanizing agent is selected from at least one of sulfur and BIBP. The accelerator is selected from at least one of zinc dibenzyl dithiocarbamate (ZBEC), tetrabenzyl thiuramized disulfide (TBZTD), and zinc diethyl dithiocarbamate (ZDEC). The lubricant is polyethylene glycol. The foaming agent is selected from at least one of 4,4'-oxobis(benzenesulfonyl hydrazine) (OBSH) and azodicarbonamide (AC).

[0066] The preparation steps of the modified red brick powder are as follows:

[0067] (a) Add the red brick powder (MBP) from construction waste to a 3% hydrochloric acid solution and stir for 30 minutes. After washing with water to remove impurities, calcine at 500-800℃ for 2 hours, then wash with water, filter through an 80-mesh sieve, and dry in an oven at 100℃ for 4 hours to obtain porous red brick powder (P-MBP).

[0068] (b) Add the obtained porous red brick powder to anhydrous ethanol, and add silane coupling agent Si-69 at a mass ratio of 1:10 to the porous red brick powder. Then stir at 80°C for 1-2 hours, filter, and obtain silane-modified red brick powder (Si-MBP).

[0069] (c) Add silane-modified red brick powder to a Tris-HCl buffer solution with pH=8.5, and add a dopamine solution with a concentration of 2 mg / mL at a rate of 10 mL / g. Stir for 12 hours to ensure that dopamine self-polymerizes and coats the powder surface to obtain red brick powder coated with polydopamine (PDA-Si-MBP).

[0070] (d) Add 2-3% MgAl-LDH suspension to the red brick powder coated with polydopamine at a rate of 3 mL / g, disperse ultrasonically for 20 minutes, filter, and vacuum dry at 80℃ for 4 hours to obtain modified red brick powder (LDH-PDA-Si-MBP).

[0071] The preparation method of the high-performance EPDM rubber foam material includes the following steps:

[0072] 1) First, vacuum dry the modified red brick powder at 80-120℃ for 2-4 hours;

[0073] 2) Place the EPDM in a two-roll mill or internal mixer and plasticize it at 60-90℃ for 3-5 minutes;

[0074] 3) Add carbon black, light calcium carbonate, zinc oxide, stearic acid, paraffin oil, lubricant and dried modified red brick powder to the masticated EPDM in sequence, and mix at 80-100℃ for 8-12 minutes to make the filler evenly dispersed.

[0075] 4) After the materials are fully mixed, cool to 50-70℃, then add accelerator, vulcanizing agent and foaming agent, and continue to mix at 60-80℃ for 5-8 minutes;

[0076] 5) Place the compound obtained in step 4) into a two-roll mill and plasticize it for 10-15 minutes at 40-60℃, and perform multiple opening and closing operations to remove the gas generated during the mixing process and improve the foaming uniformity.

[0077] 6) Place the compound obtained in step 5) into a mold, heat it to 155℃ at a rate of 2-3℃ / min, and keep it at that temperature for 25 minutes to vulcanize and foam, thus obtaining a high-performance EPDM rubber foam material.

[0078] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0079] The red brick powder used in the examples had a BET specific surface area of ​​30-80 m² / g and a particle size controlled between 20-50 μm. The EPDM rubber used was Lanxess Keltan 6950. The carbon black used was Cabot Vulcan N330. The paraffin oil used was Chevron Paralux 6001. The vulcanizing agent used was sulfur. The accelerator used was TBZTD. The lubricant used was polyethylene glycol 2000. The foaming agent used was OBSH. Example

[0080] 1) Add MBP to a 3% hydrochloric acid solution and stir for 30 minutes. Wash with water to remove impurities. Then calcine at 600℃ for 2 hours. Wash with water again, filter through an 80-mesh sieve, and dry in an oven at 100℃ for 4 hours to obtain P-MBP.

[0081] 2) Take P-MBP, add it to anhydrous ethanol, and add a 5% silane coupling agent Si-69 solution at a mass ratio of P-MBP to Si-69 of 10:1. Stir at 80°C for 1 hour, filter, and obtain Si-MBP.

[0082] 3) Add Si-MBP to a Tris-HCl buffer solution at pH=8.5, and add 2 mg / mL DA solution at a rate of 10 mL / g. Stir for 12 hours to obtain PDA-Si-MBP.

[0083] 4) Take PDA-Si-MBP and add MgAI-LDH suspension with a mass concentration of 2% at a rate of 3 mL / g. After ultrasonic dispersion for 20 minutes, filter and vacuum dry at 80℃ for 4 hours to obtain LDH-PDA-Si-MBP composite filler.

[0084] 5) According to the weight parts, 40 parts of the obtained LDH-PDA-Si-MBP composite filler were vacuum dried at 80℃ for 2h;

[0085] 6) Place 100 parts of EPDM in a two-roll mill or internal mixer and plasticize at 60°C for 5 minutes;

[0086] 7) Add 6 parts carbon black, 38 parts light calcium carbonate, 10 parts zinc oxide, 2 parts stearic acid, 15 parts paraffin oil, 1.5 parts lubricant and dried LDH-PDA-Si-MBP composite filler to the plasticized EPDM in sequence, and mix at 80℃ for 10 minutes to make the filler evenly dispersed.

[0087] 8) After the materials are fully mixed, cool to 60°C, then add 1.5 parts of accelerator, 1.0 part of vulcanizing agent and 5 parts of foaming agent, and continue to mix at 80°C for 5 minutes.

[0088] 9) Place the compound obtained in step 8) into a two-roll mill and plasticize it for 10 minutes at 60°C, and perform multiple opening and closing operations to remove the gas generated during the mixing process.

[0089] 10) Place the compound obtained in step 9) into a mold, heat it to 155°C at a rate of 2°C / min, keep it at that temperature for 25 minutes, and vulcanize and foam it to obtain a high-performance EPDM rubber foam material.

[0090] Comparative Example 1

[0091] 1) By weight, place 100 parts of EPDM in a two-roll mill or internal mixer and plasticize at 60°C for 5 minutes;

[0092] 2) Add 6 parts carbon black, 38 parts light calcium carbonate, 10 parts zinc oxide, 2 parts stearic acid, 15 parts paraffin oil, and 1.5 parts lubricant to the plasticized EPDM in sequence, and mix at 80°C for 10 minutes to ensure uniform dispersion of the filler.

[0093] 3) After the materials are fully mixed, cool to 60°C, then add 1.5 parts of accelerator, 1.0 part of vulcanizing agent and 5 parts of foaming agent, and continue to mix at 80°C for 5 minutes;

[0094] 4) Place the compound obtained in step 3) into a two-roll mill and plasticize it for 10 minutes at 60°C. Perform multiple opening and closing operations to remove the gas generated during the mixing process.

[0095] 5) Place the compound obtained in step 4) into a mold, heat it to 155°C at a rate of 2°C / min, keep it at that temperature for 25 minutes, and vulcanize and foam it to obtain EPDM rubber foam material.

[0096] Comparative Example 2

[0097] 1) Add MBP to a 3% hydrochloric acid solution and stir for 30 minutes. Wash with water to remove impurities. Then calcine at 600℃ for 2 hours. Wash with water again, filter through an 80-mesh sieve, and dry in an oven at 100℃ for 4 hours to obtain P-MBP.

[0098] 2) According to the weight parts, 40 parts of the obtained P-MBP were vacuum dried at 80℃ for 2h;

[0099] 3) Place 100 parts of EPDM in a two-roll mill or internal mixer and plasticize at 60°C for 5 minutes;

[0100] 4) Add 6 parts carbon black, 38 parts light calcium carbonate, 10 parts zinc oxide, 2 parts stearic acid, 15 parts paraffin oil, 1.5 parts lubricant and dried P-MBP to the masticated EPDM in sequence, and mix at 80℃ for 10 minutes to make the filler evenly dispersed.

[0101] 5) After the materials are fully mixed, cool to 60°C, then add 1.5 parts of accelerator, 1.0 part of vulcanizing agent and 5 parts of foaming agent, and continue to mix at 80°C for 5 minutes.

[0102] 6) Place the compound obtained in step 5) into a two-roll mill and plasticize it for 10 minutes at 60°C. Perform multiple opening and closing operations to remove the gas generated during the mixing process.

[0103] 7) Place the compound obtained in step 6) into a mold, heat it to 155°C at a rate of 2°C / min, keep it at that temperature for 25 minutes, and vulcanize and foam it to obtain EPDM rubber foam material.

[0104] Comparative Example 3

[0105] 1) Add MBP to a 3% hydrochloric acid solution and stir for 30 minutes. Wash with water to remove impurities. Then calcine at 600℃ for 2 hours. Wash with water again, filter through an 80-mesh sieve, and dry in an oven at 100℃ for 4 hours to obtain P-MBP.

[0106] 2) Take P-MBP, add it to anhydrous ethanol, and add a 5% silane coupling agent Si-69 solution at a mass ratio of P-MBP to Si-69 of 10:1. Stir at 80°C for 1 hour, filter, and obtain Si-MBP.

[0107] 3) According to the weight parts, 40 parts of the obtained Si-MBP were vacuum dried at 80℃ for 2h;

[0108] 4) Place 100 parts of EPDM in a two-roll mill or internal mixer and plasticize at 60°C for 5 minutes;

[0109] 5) Add 6 parts carbon black, 38 parts light calcium carbonate, 10 parts zinc oxide, 2 parts stearic acid, 15 parts paraffin oil, 1.5 parts lubricant and dried Si-MBP to the plasticized EPDM in sequence, and mix at 80℃ for 10 minutes to make the filler evenly dispersed.

[0110] 6) After the materials are fully mixed, cool to 60°C, then add 1.5 parts of accelerator, 1.0 part of vulcanizing agent and 5 parts of foaming agent, and continue mixing at 80°C for 5 minutes.

[0111] 7) Place the compound obtained in step 6) into a two-roll mill and plasticize it for 10 minutes at 60°C. Perform multiple opening and closing operations to remove the gas generated during the mixing process.

[0112] 8) Place the compound obtained in step 7) into a mold, heat it to 155°C at a rate of 2°C / min, keep it at that temperature for 25 minutes, and vulcanize and foam it to obtain EPDM rubber foam material.

[0113] Comparative Example 4

[0114] 1) Add MBP to a 3% hydrochloric acid solution and stir for 30 minutes. Wash with water to remove impurities. Then calcine at 600℃ for 2 hours. Wash with water again, filter through an 80-mesh sieve, and dry in an oven at 100℃ for 4 hours to obtain P-MBP.

[0115] 2) Take P-MBP, add it to anhydrous ethanol, and add a 5% silane coupling agent Si-69 solution at a mass ratio of P-MBP to Si-69 of 10:1. Stir at 80°C for 1 hour, filter, and obtain Si-MBP.

[0116] 3) Add Si-MBP to a Tris-HCl buffer solution at pH=8.5, and add 2 mg / mL DA solution at a rate of 10 mL / g. Stir for 12 hours, filter, and obtain PDA-Si-MBP.

[0117] 4) According to the weight parts, 40 parts of the obtained PDA-Si-MBP were vacuum dried at 80℃ for 2h;

[0118] 5) Place 100 parts of EPDM in a two-roll mill or internal mixer and plasticize at 60°C for 5 minutes;

[0119] 6) Add 6 parts carbon black, 38 parts light calcium carbonate, 10 parts zinc oxide, 2 parts stearic acid, 15 parts paraffin oil, 1.5 parts lubricant and dried PDA-Si-MBP to the plasticized EPDM in sequence, and mix at 80℃ for 10 minutes to make the filler evenly dispersed.

[0120] 7) After the materials are fully mixed, cool to 60°C, then add 1.5 parts of accelerator, 1.0 part of vulcanizing agent and 5 parts of foaming agent, and continue to mix at 80°C for 5 minutes.

[0121] 8) Place the compound obtained in step 7) into a two-roll mill and plasticize it for 10 minutes at 60°C. Perform multiple opening and closing operations to remove the gas generated during the mixing process.

[0122] 9) Place the compound obtained in step 8) into a mold, heat it to 155°C at a rate of 2°C / min, keep it at that temperature for 25 minutes, and vulcanize and foam it to obtain EPDM rubber foam material.

[0123] Comparative Example 5

[0124] 1) Add MBP to a 3% hydrochloric acid solution and stir for 30 minutes. Wash with water to remove impurities. Then calcine at 600℃ for 2 hours. Wash with water again, filter through an 80-mesh sieve, and dry in an oven at 100℃ for 4 hours to obtain P-MBP.

[0125] 2) Take P-MBP, add it to anhydrous ethanol, and add a 5% silane coupling agent Si-69 solution at a mass ratio of P-MBP to Si-69 of 10:1. Stir at 80°C for 1 hour, filter, and obtain Si-MBP.

[0126] 3) Add Si-MBP to a Tris-HCl buffer solution at pH=8.5, and add 2 mg / mL DA solution at a rate of 10 mL / g. Stir for 12 hours, filter, and obtain PDA-Si-MBP.

[0127] 4) According to the weight parts, 40 parts of the obtained PDA-Si-MBP were vacuum dried at 80℃ for 2h;

[0128] 5) Place 100 parts of EPDM in a two-roll mill or internal mixer and plasticize at 60°C for 5 minutes;

[0129] 6) Add 6 parts carbon black, 38 parts light calcium carbonate, 10 parts zinc oxide, 2 parts stearic acid, 15 parts paraffin oil, 1.5 parts lubricant, 4 parts MgAl-LDH and dried PDA-Si-MBP to the plasticized EPDM in sequence, and mix at 80℃ for 10 minutes to make the filler evenly dispersed.

[0130] 7) After the materials are fully mixed, cool to 60°C, then add 1.5 parts of accelerator, 1.0 part of vulcanizing agent and 5 parts of foaming agent, and continue to mix at 80°C for 5 minutes.

[0131] 8) Place the compound obtained in step 7) into a two-roll mill and plasticize it for 10 minutes at 60°C. Perform multiple opening and closing operations to remove the gas generated during the mixing process.

[0132] 9) Place the compound obtained in step 8) into a mold, heat it to 155°C at a rate of 2°C / min, keep it at that temperature for 25 minutes, and vulcanize and foam it to obtain EPDM rubber foam material.

[0133] Table 1. Performance comparison of EPDM rubber foam materials prepared in the examples and comparative examples.

[0134]

[0135] As shown in Table 1, the EPDM foam material prepared using LDH-PDA-Si-MBP composite filler in the examples exhibits significant improvements in mechanical properties, flame retardancy, thermal stability, and cell uniformity. Compared to the EPDM foam material prepared in the comparative example, the tensile strength of the EPDM foam material obtained in the examples increased by 19.4%~38.9% (reaching a maximum of 12.5 MPa), the tear strength increased by 13.3%~37.8% (reaching a maximum of 6.2 kN / m), and the elongation at break remained at around 450%, demonstrating excellent flexibility and durability. Simultaneously, the cell uniformity was improved to over 95%, effectively improving the uniformity of the foam structure and enhancing the dimensional stability of the material. The oxygen index (LOI) reached a maximum of 31.2%, an increase of 5.2%~9.5% compared to the comparative example, significantly enhancing the flame retardant properties. The heat release rate (HRR) was reduced by 9.1% to 38.6%, effectively reducing heat release during combustion and meeting the requirements of applications such as rail transit and automotive seals with high flame retardant performance. The thermal decomposition temperature (TGA) was increased by 14.3% to 21.4%, reaching a maximum of 340℃, significantly improving the material's heat resistance. Overall, the EPDM foam material in the examples demonstrated excellent performance across multiple performance indicators, fully proving the modification effect of the LDH-PDA-Si-MBP composite filler.

[0136] In summary, this invention achieves comprehensive optimization of EPDM foam materials in terms of mechanical properties, flame retardancy, cell structure stability, and wear resistance through multiple modifications of fillers and optimized foaming and vulcanization processes, which has significant industrial application value and broad market prospects.

[0137] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A high-performance EPDM rubber foam material based on modified red brick powder, characterized in that, The material is prepared from the following raw materials in parts by weight: 100 parts of EPDM rubber 10-40 parts carbon black 40 parts of modified red brick powder 30-50 parts of light calcium carbonate 10-20 parts paraffin oil 5-15 parts zinc oxide Vulcanizing agent 0.5-3 parts, Accelerator 0.5-2 parts, 1-5 parts stearic acid Lubricant 0.5-3 parts, 5-15 parts of foaming agent; The preparation steps of the modified red brick powder are as follows: (a) Add red brick powder to a 3% hydrochloric acid solution and stir for 30 minutes. After washing with water to remove impurities, calcine at 500-800℃ for 2 hours. Then wash with water, filter, and dry to obtain porous red brick powder. (b) Add porous red brick powder to anhydrous ethanol and add silane coupling agent Si-69. Then stir at 80°C for 1-2 hours and filter to obtain silane-modified red brick powder. (c) The obtained silane-modified red brick powder was added to a Tris-HCl buffer solution with pH=8.5, and 2 mg / mL of dopamine solution was added and stirred for 12 hours to obtain red brick powder coated with polydopamine. (d) The obtained red brick powder coated with polydopamine was added to a MgAl-LDH suspension with a mass concentration of 2-3%, ultrasonically dispersed and filtered, and vacuum dried at 80°C for 4 hours to obtain the modified red brick powder.

2. The high-performance EPDM rubber foam material according to claim 1, characterized in that, The mass ratio of porous red brick powder to silane coupling agent Si-69 used in step (b) is 10:1; In step (c), the amount of dopamine solution used is 10 mL per gram of silane-modified red brick powder. In step (d), the amount of MgAl-LDH suspension used is 3 mL per gram of red brick powder coated with polydopamine.

3. The high-performance EPDM rubber foam material according to claim 1, characterized in that, The vulcanizing agent is selected from at least one of sulfur and BIBP.

4. The high-performance EPDM rubber foam material according to claim 1, characterized in that, The accelerator is selected from at least one of zinc dibenzyl dithiocarbamate, tetrabenzyl thiuramized disulfide, and zinc diethyl dithiocarbamate.

5. The high-performance EPDM rubber foam material according to claim 1, characterized in that, The lubricant is polyethylene glycol.

6. The high-performance EPDM rubber foam material according to claim 1, characterized in that, The foaming agent is selected from at least one of 4,4'-oxobisbenzenesulfonyl hydrazine and azodicarbonamide.

7. A method for preparing the high-performance EPDM rubber foam material as described in claim 1, characterized in that, Includes the following steps: 1) First, vacuum dry the modified red brick powder at 80-120℃ for 2-4 hours; 2) Plasticize the EPDM at 60-90℃ for 3-5 minutes; 3) Add carbon black, light calcium carbonate, zinc oxide, stearic acid, paraffin oil, lubricant and dried modified red brick powder to the masticated EPDM in sequence, and mix at 80-100℃ for 8-12 minutes. 4) After the materials are fully mixed, cool to 50-70℃, then add accelerator, vulcanizing agent and foaming agent, and continue to mix at 60-80℃ for 5-8 minutes; 5) The compound obtained in step 4) is subjected to secondary plasticizing and then vulcanized and foamed to obtain the high-performance EPDM rubber foam material.

8. The method for preparing high-performance EPDM rubber foam material according to claim 7, characterized in that, The secondary plasticizing temperature is 40-60℃, and the time is 10-15 minutes.

9. The method for preparing high-performance EPDM rubber foam material according to claim 7, characterized in that, The vulcanization foaming is carried out by gradually increasing the temperature at a rate of 2-3 ℃ / min, raising the temperature to 155 ℃, and holding it at that temperature for 25 min.

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