Composite material and method for producing same, sealing strip

Abstract

The application relates to a composite material and a preparation method and a sealing strip thereof. The composite material is prepared from the following components by weight percentage: 25-40% of ethylene-propylene-diene rubber, 10-20% of polypropylene, 20-40% of filling oil, 5-12% of reinforcing filler, 5-15% of wear-resistant additive, 2-5% of compatilizer, 2-4% of crosslinking agent, and 0.5-1.5% of accelerator; the reinforcing filler comprises one or more of reinforcing carbon black and silica coupling agent modified white carbon black master batch; and the mass ratio of the ethylene-propylene-diene rubber to the reinforcing filler is (2-7):1. The composite material has low compression permanent deformation, heat resistance, aging resistance and high wear resistance, and has good process stability.

Description

Technical Field

[0001] This application relates to the field of materials technology, and in particular to composite materials and their preparation methods, and sealing strips. Background Technology

[0002] Thermoplastic vulcanizate (TPV) products refer to high-molecular-weight elastomer materials prepared using a dynamic vulcanization process with polypropylene (PP) and ethylene propylene diene monomer (EPDM) rubber as the dispersed phase and plastic as the continuous phase. It possesses both the excellent physical and mechanical properties of elastomers and the excellent processing characteristics of plastics, making it easy to mold and process, recyclable, and environmentally friendly. Furthermore, it exhibits excellent low-temperature resistance, heat resistance, weather resistance, and resilience, and is widely used in various fields such as automobiles, construction, and electronics. While the use of TPV in sealing strips has become a mature industry in the automotive sector, EPDM rubber is currently the primary material for container sealing strips, with TPV usage accounting for a relatively small proportion. The main reason is that, according to GB / T 15846-2006 Container Door Frame Sealing Strips, compared to the requirements for automotive TPV sealing strips, container sealing strips require lower compression set and higher tensile strength (ordinary 70A TPV has a tensile strength of 5MPa~6MPa and a compression set of 35%~45% at 70℃ for 22 hours). This makes it difficult for ordinary TPV to simultaneously meet the comprehensive requirements of mechanical performance, weather resistance, appearance, and other aspects, thus delaying its widespread adoption.

[0003] As a key component ensuring the airtightness, watertightness, and weather resistance of containers, container sealing strips must withstand harsh environments such as compression, friction, ultraviolet radiation, and high and low temperature cycles for extended periods. This requires both excellent elastic recovery (low compression set) and surface abrasion resistance. While traditional EPDM / PP-based TPV materials possess good elasticity and processability, they are prone to permanent deformation under long-term compression and lack sufficient surface abrasion resistance, thus affecting the seal's lifespan.

[0004] In traditional techniques, dynamic vulcanization using peroxide or sulfur systems is often employed to improve compression set. However, the former is prone to material scorching and has a narrow processing window, while the latter suffers from strong odor and poor environmental performance. Although phenolic resin crosslinking systems are used in some rubbers, their reactivity in TPV systems is difficult to control, making it hard to balance crosslinking efficiency and processing stability. Furthermore, conventional dynamic vulcanization struggles to achieve synergistic control of uniform filler dispersion and full crosslinking, limiting the improvement of overall performance.

[0005] Therefore, there is an urgent need to develop a new type of TPV material that combines high wear resistance and low compression set. Summary of the Invention

[0006] Therefore, it is necessary to provide a composite material and its preparation method, as well as a sealing strip, which has both low compression set and high wear resistance.

[0007] This application is achieved through the following technical solution:

[0008] One aspect of this application provides a composite material, wherein the raw materials for preparing the composite material, by weight percentage, comprise the following components:

[0009] 25%~40% EPDM rubber;

[0010] Polypropylene 10%~20%;

[0011] Filler oil 20%~40%;

[0012] Reinforcing filler 5%~12%;

[0013] Wear-resistant additives 5%~15%;

[0014] Compatibilizer 2%~5%;

[0015] Crosslinking agent 2%~4%;

[0016] Accelerator 0.5%~1.5%;

[0017] The reinforcing filler includes one or more of reinforcing carbon black and silane coupling agent modified silica masterbatch;

[0018] The mass ratio of the EPDM rubber to the reinforcing filler is (2~7):1.

[0019] In some embodiments, the raw materials for preparing the composite material, by weight percentage, include the following components:

[0020] 25%~35% EPDM rubber;

[0021] Polypropylene 10%~17%;

[0022] Filler oil 20%~40%;

[0023] Reinforcing filler 5%~10%;

[0024] Wear-resistant additives 10%~15%;

[0025] Compatibilizer 2%~5%;

[0026] Crosslinking agent 2%~4%;

[0027] Accelerator 0.5%~1.5%.

[0028] In some embodiments, the reinforcing carbon black has an oil absorption value of 102 cm⁻¹. 3 / 100g~115 cm 3 / 100g;

[0029] And / or, the average particle size of the reinforcing carbon black is 26 nm to 30 nm.

[0030] In some embodiments, the EPDM rubber has a Mooney viscosity of 60-120 at 125°C;

[0031] And / or, the ethylene content in the EPDM rubber is 60%~80% by mass;

[0032] And / or, the ethylene-propylene diene monomer (EPDM) rubber contains 4% to 5% by mass;

[0033] And / or, the wear-resistant additive includes one or more of polytetrafluoroethylene, modified silicone, and ultra-high molecular weight polyethylene;

[0034] And / or, the silane coupling agent includes one or more of Si69 and Si75.

[0035] In some embodiments, the filler oil includes one or more of white oil and paraffin oil;

[0036] And / or, the compatibilizer includes one or more of polypropylene grafted maleic anhydride and ethylene propylene diene rubber grafted maleic anhydride.

[0037] And / or, the crosslinking agent includes octylphenol resin;

[0038] And / or, the accelerator includes one or more of SnCl2·2H2O, stearic acid, and zinc oxide.

[0039] In some embodiments, the raw materials for preparing the composite material further include additives, which include one or more of lubricants, antioxidants, and light stabilizers;

[0040] Optionally, the lubricant includes one or more of stearates, polyethylene wax, silicone masterbatch, and fluorinated processing aids;

[0041] Optionally, the antioxidant includes one or more of antioxidant 1010, antioxidant 1076, and antioxidant 168;

[0042] Optionally, the light stabilizer includes one or more of benzotriazole UV absorbers, benzophenone UV absorbers, and hindered amine light stabilizers.

[0043] Another aspect of this application provides a method for preparing the above-mentioned composite material, comprising the following steps:

[0044] The EPDM rubber, the polypropylene, the reinforcing filler, the wear-resistant additive, the compatibilizer, and the additives are mixed evenly and then extruded to prepare the first intermediate.

[0045] The filler oil is added to the intermediate, and extrusion granulation is performed to prepare the second intermediate;

[0046] The crosslinking agent and the accelerator are added to the second intermediate using a two-sided feeding method to perform crosslinking treatment.

[0047] In some embodiments, the reinforcing filler comprises reinforcing carbon black and silane coupling agent modified silica masterbatch, wherein the mass ratio of the reinforcing carbon black to the silane coupling agent modified silica masterbatch is 1:(0.5~1).

[0048] In some embodiments, the wear-resistant additive includes polytetrafluoroethylene and modified silicone, wherein the mass ratio of polytetrafluoroethylene to modified silicone is 1:(0.5~1).

[0049] Another aspect of this application provides a sealing strip comprising the above-described composite material or a composite material prepared by the above-described method.

[0050] The composite material described in this application incorporates wear-resistant additives to reduce adhesive wear and abrasive wear. Simultaneously, the addition of specific reinforcing materials ensures "reinforcement without deteriorating elasticity," guaranteeing synergistic optimization of wear resistance and low compression set. Furthermore, the synergistic effect of filler oil, compatibilizer, crosslinking agent, and accelerator, achieved by controlling the specific proportions of each raw material and the types of specific reinforcing materials and the mass ratio of EPDM rubber to reinforcing filler, allows for the synergistic effect of all components. This results in a composite material with high hardness, low compression set, and low abrasion, overcoming the technical bottleneck of traditional TPV materials that struggle to balance low compression set and high wear resistance, thus meeting the application requirements of high-end container sealing strips.

[0051] Furthermore, in the preparation process of this application, a two-step extrusion granulation method is used, and dynamic vulcanization and double-sided feeding process are adopted to achieve precise control of crosslinking. This design realizes the spatiotemporal separation of physical mixing and chemical crosslinking, avoiding risks such as early crosslinking, scorching, and gelation. The melt pressure fluctuation is small, ensuring the stability and uniformity of material processing and significantly reducing the performance fluctuation between batches. Detailed Implementation

[0052] To facilitate understanding of this application, a more complete description is provided below, along with preferred embodiments. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0053] The implementation of this application will be described in detail below with reference to some implementation methods and embodiments. This embodiment is implemented based on the technical solution of this application, and provides detailed implementation methods and specific operation processes, but the protection scope of this application is not limited to the following embodiments.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0055] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0056] In this application, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0057] In this application, terms such as "further" and "especially" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0058] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0059] In this application, when numerical intervals (i.e., numerical ranges) are mentioned, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, including the two endpoint integers of the numerical range, as well as every integer between the two endpoints, is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include numerical interval types such as percentage intervals, ratio intervals, and proportion intervals.

[0060] In this application, the term "room temperature" generally refers to 4℃ to 35℃, and preferably 20℃ ± 5℃. In some embodiments of this application, room temperature refers to 20℃ to 30℃.

[0061] In this application, unless otherwise specified, the temperature parameters are permitted to be either constant temperature treatment or variations within a certain temperature range. It should be understood that the constant temperature treatment allows temperature fluctuations within the precision range controlled by the instrument. Fluctuations are permitted within ranges such as ±5℃, ±4℃, ±3℃, ±2℃, and ±1℃.

[0062] In this application, if the unit of a data range is only followed by the right endpoint, it indicates that the units of the left and right endpoints are the same. For example, 2~5h means that the units of the left endpoint "2" and the right endpoint "5" are both h (hours).

[0063] One embodiment of this application provides a composite material, wherein the raw materials for preparing the composite material, by weight percentage, include the following components:

[0064] 25%~40% EPDM rubber;

[0065] Polypropylene 10%~20%;

[0066] Filler oil 20%~40%;

[0067] Reinforcing filler 5%~12%;

[0068] Wear-resistant additives 5%~15%;

[0069] Compatibilizer 2%~5%;

[0070] Crosslinking agent 2%~4%;

[0071] Accelerator 0.5%~1.5%;

[0072] The aforementioned reinforcing fillers include one or more of reinforcing carbon black and silane coupling agent modified silica masterbatch;

[0073] The mass ratio of the above-mentioned EPDM rubber to the above-mentioned reinforcing filler is (2~7):1.

[0074] The composite material described in this application incorporates wear-resistant additives to reduce adhesive wear and abrasive wear. Simultaneously, the addition of specific reinforcing materials ensures "reinforcement without deteriorating elasticity," guaranteeing synergistic optimization of wear resistance and low compression set. Furthermore, the synergistic effect of filler oil, compatibilizer, crosslinking agent, and accelerator, achieved by controlling the specific proportions of each raw material and the types of specific reinforcing materials and the mass ratio of EPDM rubber to reinforcing filler, allows for the synergistic effect of all components. This results in a composite material with high hardness, low compression set, and low abrasion, overcoming the technical bottleneck of traditional TPV materials that struggle to balance low compression set and high wear resistance, thus meeting the application requirements of high-end container sealing strips.

[0075] It should be noted that the value range for EPDM rubber is "25%~40%", which means taking the minimum and maximum values ​​within the range of 25%~40%, as well as every value between these minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and the following point values: 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%; or any range consisting of any two of these values, as an example, including: 25%~35%.

[0076] The polypropylene value range is "10%~20%", which means the minimum and maximum value of the range of 10%~20%, as well as every value between the minimum and maximum value. Specific examples include, but are not limited to, the point values ​​in the examples and the following point values: 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%; or any range of any two of these values, for example, including: 15%~20%.

[0077] The filler oil's value range is "20%~40%", which means taking the minimum and maximum values ​​within this range, as well as every value between these values. Specific examples include, but are not limited to, the point values ​​in the embodiments and the following point values: 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%; or any range consisting of any two of these values, for example, including: 20%~35%.

[0078] The value range of the reinforcing filler is "5%~12%", which means taking the minimum and maximum values ​​within the range of 5%~12%, as well as every value between these minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and the following point values: 5%, 6%, 7%, 8%, 9%, 10%, 11%, or 12%; or any range consisting of any two of these values, for example, including: 5%~10%.

[0079] The wear-resistant additive's value range is "5%~15%", which means taking the minimum and maximum values ​​within the range of 5%~15%, as well as every value between these minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and the following point values: 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%; or any range consisting of any two of these values, for example, including: 5%~10%.

[0080] The compatibilizer value range is "2%~5%", which means the minimum and maximum value of the range of 2%~5%, as well as every value between the minimum and maximum value. Specific examples include, but are not limited to, the point values ​​in the embodiments and the following point values: 2%, 3%, 4% or 5%; or any range of any two of these values, for example, including: 3%~5%.

[0081] The crosslinking agent can be selected from the range of "2% to 4%", which includes the minimum and maximum values ​​of the range, as well as every value between these values. Specific examples include, but are not limited to, the point values ​​in the embodiments and the following point values: 2%, 3%, or 4%; or any range of any two of these values, for example, including: 3% to 4%.

[0082] The accelerator's value range is "0.5%~1.5%", which means it can take the minimum and maximum values ​​within the range of 0.5%~1.5%, as well as every value between these minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and the following point values: 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, or 1.5%; or a range consisting of any two of these values, for example, including: 0.5%~1%.

[0083] In some embodiments, the mass ratio of the EPDM rubber to the reinforcing filler is (2~7):1, for example, the mass ratio can be 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3.0:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, 4.0:1, 4.1: 1, 4.2:1, 4.3:1, 4.4:1, 4.5:1, 4.6:1, 4.7:1, 4.8:1, 4.9:1, 5.0:1, 5.1:1, 5.2:1, 5.3:1, 5.4:1, 5.5:1, 5.6:1, 5.7:1, 5.8:1, 5.9:1, 6.0:1, 6.1:1, 6.2:1, 6.3:1, 6.4:1, 6.5:1, 6.6:1, 6.7:1, 6.8:1, 6.9:1, or 7.0:1.

[0084] In some embodiments, the raw materials for preparing the above composite material, by weight percentage, include the following components:

[0085] 25%~35% EPDM rubber;

[0086] Polypropylene 10%~17%;

[0087] Filler oil 20%~40%;

[0088] Reinforcing filler 5%~10%;

[0089] Wear-resistant additives 10%~15%;

[0090] Compatibilizer 2%~5%;

[0091] Crosslinking agent 2%~4%;

[0092] Accelerator 0.5%~1.5%.

[0093] It is understandable that controlling the proportions of raw materials in the preparation of composite materials within the above range results in better low compression set, heat resistance, aging resistance, and wear resistance.

[0094] In some embodiments, the oil absorption value of the aforementioned reinforcing carbon black is 102 cm⁻¹. 3 / 100g~115 cm 3 For example, the oil absorption value per 100g could be 102 cm³. 3 / 100g, 103 cm 3 / 100g, 104 cm 3 / 100g, 105 cm 3 / 100g, 106cm 3 / 100g, 107 cm 3 / 100g, 108 cm 3 / 100g, 109 cm 3 / 100g, 110 cm 3 / 100g, 111 cm 3 / 100g, 112cm 3 / 100g, 113 cm 3 / 100g, 114 cm 3 / 100g or 115 cm 3 / 100g.

[0095] In some embodiments, the average particle size of the above-mentioned reinforcing carbon black is 26 nm to 30 nm. For example, the average particle size can be 26 nm, 27 nm, 28 nm, 29 nm or 30 nm.

[0096] In a specific example, the aforementioned reinforcing carbon black includes high abrasion furnace black (HAF).

[0097] Understandably, the aforementioned reinforcing carbon black has the characteristics of high reinforcement, high wear resistance, and excellent comprehensive performance. While providing excellent wear resistance, it avoids the increase in compression set caused by excessive structure.

[0098] In some embodiments, the Mooney viscosity of the EPDM rubber at 125°C is 60~120. For example, the Mooney viscosity can be 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115 or 120.

[0099] In some embodiments, the ethylene content in the EPDM rubber is 60% to 80% by mass. For example, the ethylene content by mass can be 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, or 80%.

[0100] In some embodiments, the ethylene-propylene diene monomer (EPDM) rubber contains 4% to 5% by mass.

[0101] In some of these embodiments, the polypropylene used is a homopolymer polypropylene with a melt index of 230°C and a yield of ≤3g / 10min at 2.16kg.

[0102] In some embodiments, the wear-resistant additives mentioned above include one or more of polytetrafluoroethylene, modified silicone, and ultra-high molecular weight polyethylene.

[0103] In one specific example, the aforementioned wear-resistant additives include polytetrafluoroethylene micropowder and modified silicone powder.

[0104] It is understood that polytetrafluoroethylene (PTFE) micro powder has extremely low surface energy (approximately 18 mN / m to 25 mN / m) and self-lubricating properties, with a friction coefficient of only 0.04 to 0.10. It forms a micron-scale lubricating phase in the TPV matrix, which migrates to the material surface during friction to form a transfer film, effectively isolating the grinding surfaces and reducing adhesive wear and abrasive wear. Preferred parameters are: average particle size of 1 μm to 10 μm, more preferably 3 μm to 6 μm; specific surface area of ​​5 m² / g to 20 m² / g.

[0105] The modified silicone powder mentioned above is organosilicon-modified silica or polysiloxane microspheres, possessing both lubricity and reinforcing properties. Amino-functionalized modified polysiloxane microspheres are preferred, as they can form a certain interfacial bond with the EPDM / PP matrix. The silicone molecular chains are flexible and oriented under shear force, reducing surface friction; simultaneously, their rigid core structure can inhibit microcrack propagation. Compared to PTFE, it has less negative impact on mechanical properties and improves mold release and surface gloss. Preferred parameters: average particle size of 1μm~5μm.

[0106] The PTFE provides long-lasting lubrication, while the silicone improves dispersibility and interfacial bonding, which can synergistically reduce wear.

[0107] In some embodiments, the silane coupling agent described above includes one or more of Si69 and Si75.

[0108] In a specific example, AS70 silica can be selected, which has the characteristics of accelerating vulcanization, giving the product high elasticity, low pressure deformation, low heat generation and flexural strength, anti-yellowing and UV protection.

[0109] Understandably, silica is rich in silanol groups (-SiOH) on its surface. After modification with the silane coupling agent Si69, it can form a chemical / physical bond with the EPDM molecular chain, improving the modulus and tear strength of the vulcanized rubber network, especially enhancing cut resistance and edge durability, which is crucial for the sealing strips of container doors that are frequently opened and closed. In addition, the high hardness and rigidity of silica can resist abrasive indentation, and together with lubricating wear-resistant additives such as PTFE / silicone, it forms a "hard-soft" composite wear-resistant mechanism to synergistically improve wear resistance.

[0110] In some embodiments, the filler oil includes one or more of white oil and paraffin oil.

[0111] In some embodiments, the paraffin oil described above has a kinematic viscosity of 60-150 mm. 2 / s, paraffin oil with an open flash point above 230℃.

[0112] In some embodiments, the compatibilizer includes one or more of polypropylene grafted maleic anhydride and ethylene propylene diene monomer (EPDM) grafted maleic anhydride.

[0113] Since composite materials are blends of various materials, the addition of compatibilizers allows the various components in the composite material to further form a whole and be tightly bound together, reducing the tendency of low molecular weight polymer components to separate from the melt. As a result, the composite material will not produce material residue during extrusion molding due to friction with the die, thus improving the phenomenon of material residue accumulation at the die.

[0114] In some embodiments, the crosslinking agent described above includes octylphenol aldehyde resin.

[0115] In some embodiments, the aforementioned promoters include one or more of SnCl2·2H2O, stearic acid, and zinc oxide.

[0116] In some embodiments, the raw materials for preparing the above-mentioned composite material also include 0.5% to 1.5% of additives, which include one or more of lubricants, antioxidants and light stabilizers.

[0117] Optionally, the above-mentioned lubricant includes one or more of stearates, polyethylene wax, silicone masterbatch, and fluorinated processing aids;

[0118] Optionally, the antioxidants mentioned above include one or more of antioxidants 1010, antioxidant 1076, and antioxidant 168;

[0119] Optionally, the light stabilizers mentioned above include one or more of benzotriazole UV absorbers, benzophenone UV absorbers, and hindered amine light stabilizers.

[0120] Another embodiment of this application provides a method for preparing the above-mentioned composite material, including steps S100 to S300.

[0121] Step S100: After uniformly mixing the above-mentioned EPDM rubber, polypropylene, reinforcing filler, wear-resistant additive, compatibilizer and additives, the mixture is extruded to prepare the first intermediate.

[0122] Step S200: Add the filler oil to the above intermediate, and perform extrusion granulation to prepare the second intermediate.

[0123] In some embodiments, the above-mentioned intermediate is added from the main feed port, and the filling oil is injected from the 3rd to 5th zones of the twin screw through a metering oil pump for oil-filled extrusion granulation. After drying, a second intermediate is obtained, wherein the rotation speed is 200 rpm to 300 rpm and the melting temperature is 160°C to 200°C.

[0124] Step S300: Using a two-sided feeding method, the crosslinking agent and the accelerator are added to the second intermediate to perform crosslinking treatment.

[0125] In some embodiments, the crosslinking agent is a phenolic resin, which is cryogenically pulverized or mechanically ground to 80-200 mesh and vacuum dehumidified and dried at 70-80°C for 2-4 hours before use to remove adsorbed water. During the second extrusion, it is premixed with stearic acid and / or zinc oxide and added as dry powder through the middle side feed port (zone 6) using a loss-in-weight feeder. SnCl2·2H2O is added by side feeding in zone 7.

[0126] Understandably, this method enables uniform contact between the crosslinking agent and the accelerator at the microscale, allowing them to melt, activate, and react synchronously after entering the high-temperature zone of the twin-screw extruder. This results in a highly uniform crosslinking network, reducing compression set and improving elastic recovery. Furthermore, the mid-section side-feeding strategy ensures that the crosslinking agent and accelerator only enter the melt in the designated high-temperature, high-shear zone (e.g., zone 6-8), maximizing the delay of the reaction initiation point and effectively avoiding process risks such as equipment blockage, melt pressure fluctuations, and coke particle formation. In addition, this not only improves the crosslinking conversion rate but also reduces unreacted phenolic residue, preventing later precipitation or aging problems.

[0127] Understandably, this dual-sided feeding method can minimize the premature cross-linking of the rubber phase, ensuring that EPDM / PP is fully melted and blended before triggering cross-linking. The two components are dispersed separately and mixed and reacted instantaneously in the high shear zone, resulting in a more uniform network.

[0128] In some embodiments, during the crosslinking process described above, the rotation speed is 300 rpm to 500 rpm, the temperature in zones one to four is 150°C to 180°C, and the temperature from zone five to the extruder outlet is 180°C to 220°C. The extruder has a length-to-diameter ratio (L / D) of 48 to 60, and multiple sets of kneading blocks are configured in the rear section to provide high shear force.

[0129] Under these conditions, the EPDM phase is fully broken down and undergoes a phenol-induced cross-linking reaction to form a stable "sea-island" structure. The melt is then extruded through a die and water-cooled to form pellets, thus obtaining the composite material.

[0130] In some embodiments, the reinforcing filler includes reinforcing carbon black and silane coupling agent modified silica masterbatch, wherein the mass ratio of the reinforcing carbon black to the silane coupling agent modified silica masterbatch is 1:(0.5~1). For example, the mass ratio may be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9 or 1:1.

[0131] In some embodiments, the wear-resistant additive includes polytetrafluoroethylene and modified silicone, wherein the mass ratio of the polytetrafluoroethylene to the modified silicone is 1:(0.5~1). For example, the mass ratio may be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9 or 1:1.

[0132] In some embodiments, the preparation method of the above-mentioned silane coupling agent modified silica masterbatch includes the following steps A and B:

[0133] Step A: Mix silica with a silane coupling agent to prepare modified silica.

[0134] In some embodiments, the temperature of the above mixing process is 140°C to 150°C.

[0135] In some embodiments, the mixing process takes 3 to 8 minutes.

[0136] Step B: The modified silica is mixed with EPDM rubber, the mixture is discharged and pelletized to obtain silica masterbatch modified with silane coupling agent.

[0137] In some embodiments, the temperature of the above-mentioned mixing process is 140°C to 150°C.

[0138] In some embodiments, the mixing process takes 5 to 15 minutes.

[0139] In some embodiments, the mass ratio of the modified silica to EPDM rubber is (3~5):(5~7).

[0140] In a specific example, the mass ratio of the modified silica to EPDM rubber is 4:6.

[0141] In this process, pretreating precipitated silica with a silane coupling agent is a key step to improve its dispersibility and compatibility while avoiding damage to compression set. During masterbatch preparation, the silica is completely coated with EPDM and crosslinks with the rubber phase during dynamic vulcanization, forming an integrated "filler-crosslinking network" structure. This maximizes reinforcement efficiency and minimizes negative impacts on compression set. Preparing EPDM / silica masterbatch is the best practice to ensure stable performance and reliable processing. Through this process, while introducing silica, it is ensured that it plays a reinforcing role without deteriorating elasticity, ensuring synergistic optimization of abrasion resistance and low compression set.

[0142] The phenolic resin crosslinking system used in this application is free of sulfur, halogens, and peroxide residues, and has no irritating odor. It meets RoHS, REACH, and international environmental standards for marine container materials, and is suitable for special container scenarios such as food and pharmaceutical products that are sensitive to odor and volatile organic compounds (VOCs).

[0143] The TPV granules obtained in this application have high melt strength and good thermal stability. When extruding sealing strips, they are dimensionally stable and have a smooth surface without defects such as sharkskin or melt cracking. Furthermore, no subsequent vulcanization is required, which simplifies the end-manufacturing process and reduces energy consumption and costs.

[0144] In summary, this application, through material system innovation and process route reconstruction, simultaneously achieves breakthroughs in low compression set, high wear resistance, high process stability, and environmental friendliness without sacrificing processability. It solves the technical bottleneck of existing composite materials for container sealing strips being prone to failure during long-term service, demonstrating outstanding practicality and industrialization value. The resulting composite material exhibits excellent performance, is environmentally friendly, and has good aging resistance, making it suitable for replacing traditional EPDM materials in the preparation of container sealing strips.

[0145] Another embodiment of this application provides a sealing strip, which includes the above-described composite material or a composite material prepared by the above-described composite material preparation method.

[0146] The aforementioned composite material exhibits low compression set, excellent wear resistance, and good process stability. It can be directly used in the extrusion molding of high-performance container sealing strips, significantly improving sealing durability and service life. It can serve as a green and environmentally friendly material to replace existing traditional EPDM sealing strips in the field of container sealing strips.

[0147] To make the objectives, technical solutions, and advantages of this application clearer and more concise, the following specific embodiments are used for illustration, but this application is by no means limited to these embodiments. The embodiments described below are merely preferred embodiments of this application and can be used to describe this application, but should not be construed as limiting the scope of this application. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

[0148] To better illustrate this application, the following description, in conjunction with embodiments, further explains the content of this application.

[0149] Example 1

[0150] (1) The following raw materials are provided by mass percentage: EPDM 30%, polypropylene 11%, reinforcing filler 10%, wear-resistant additive 10%, compatibilizer 3%, additive 1%, filler oil 30%, accelerator 1%, and crosslinking agent 4%, as detailed in Table 1; among them, EPDM is from ExxonMobil's EPDM 5601, polypropylene is from Sinopec PPH-T03, high wear-resistant furnace black is from Cabot N330, white carbon black is from Evonik AS70, polytetrafluoroethylene micro powder is from Daikin MP-M, organosilicon modified silicone powder is from Silike TP series, compatibilizer is from Jia Yi Rong CMG-5001, crosslinking agent is SI SP1045, accelerator is Aladdin SnCl2·2H2O, Jinghuang ZnO, and among the additives, lubricant is Daikin DA-310ST, antioxidant is BASF B215, and light stabilizer is Lianlong UV-770D.

[0151] The preparation method of silica masterbatch is as follows: 100 parts by weight of silica and 6 parts by weight of bis-[3-(ethoxysilane)propyl]tetrasulfide (Si69) are added to a high-speed mixer and mixed at room temperature for 5 minutes. Then, the temperature is raised to 150°C and held for 30 minutes. After cooling, hydrophobic modified silica is obtained. Then, the modified silica is mixed with EPDM (selected from proprietary formulas of the same type) at a ratio of 4:6 in an internal mixer at a mixing temperature of 140~150°C for 10 minutes. After mixing, the binder is discharged and pelletized to obtain a pretreated masterbatch with a silica content of 40%.

[0152] (2) Raw material mixing: Weigh EPDM, polypropylene, reinforcing filler, wear-resistant additive, compatibilizer and additives according to the formula, mix them evenly and add them from the main feed port of the twin-screw extruder.

[0153] (3) Semi-finished product processing: The above-mentioned mixed raw materials are added from the main feed port, and the filling oil is injected from the fourth zone of the twin screw through the quantitative oil pump. Oil-filled extrusion granulation is carried out, and after drying, soft, non-crosslinked semi-finished product granules are obtained.

[0154] (4) TPV dynamic vulcanization: The TPV semi-finished particles obtained in step (3) are added from the main feed port. Phenolic resin and 0.5% zinc oxide are premixed and added in dry powder form through the middle section side feed port in zone 6. The loss-in-weight feeder is used for precise addition. 0.5% SnCl2·2H2O is added in zone 7. The composite material is obtained by controlling the extruder process.

[0155] In step (3), the main motor speed of the twin-screw extruder for semi-finished product processing is 200 rpm, and the melt temperature is 160~200℃. In step (4), the main motor speed of the PV dynamic vulcanization extruder is 400 rpm, and the process parameters include: the temperature of zones one to four is 150~180℃, and the temperature of zone five to the extrusion outlet is 180~220℃. The length-to-diameter ratio (L / D) of the extruder is 52, and multiple sets of kneading blocks are configured in the rear section to provide high shear.

[0156] (5) Performance testing: The composite materials prepared above were subjected to Shore hardness, tensile strength, elongation at break, compression set and hot air aging performance tests, respectively. The hot air aging performance test was conducted using (test method or test standard GB / T 3512-2014). Other test methods and test results are shown in Tables 3 and 4 below.

[0157] Examples 2-9

[0158] The preparation methods of the composite materials in other Examples 2-9 are basically the same as those in Example 1, except that the raw materials in Table 1 are different. Please refer to Table 1 for details.

[0159] The other steps and conditions are the same as in Example 1.

[0160] Comparative Examples 1-3

[0161] The preparation methods of the composite materials in Comparative Examples 1-3 are basically the same as those in Example 1, except that the raw materials in Table 1 are different. Please see Table 2 for details.

[0162] The other steps and conditions are the same as in Example 1.

[0163] Comparative Example 4

[0164] Compared with Example 1, Comparative Example 4 differs in that the crosslinking system in step (4) is completely mixed and fed from the 6th zone by one side.

[0165] The other steps and conditions are the same as in Example 1.

[0166] Comparative Example 5

[0167] The preparation method of the composite material in Comparative Example 5 is basically the same as that in Example 1, except that the preparation steps of the composite material are as follows:

[0168] (1) Raw material mixing: Weigh EPDM, polypropylene, commercially available carbon black, white carbon black and bis-[3-(ethoxysilane)propyl]tetrasulfide (Si69), wear-resistant additives, compatibilizers and processing aids according to the formula amount, mix them evenly and add them from the main feed port of the twin-screw extruder.

[0169] (2) Semi-finished product processing: The above-mentioned mixed raw materials are added from the main feed port, and the filling oil is injected from the fourth zone of the twin screw through the quantitative oil pump. Oil-filled extrusion granulation is carried out, and after drying, soft, non-crosslinked semi-finished product granules are obtained.

[0170] (3) TPV dynamic vulcanization: The TPV semi-finished particles obtained in step (2) are added from the main feed port. The phenolic resin and zinc oxide in the crosslinking system are premixed and then added in dry powder form through the middle section side feed port in zone 6. The feed is precisely added using a loss-in-weight feeder. SnCl2·2H2O is added in zone 7. The composite material is obtained by controlling the extruder process.

[0171] In step (2), the main motor speed of the twin-screw extruder for semi-finished product processing is 200 rpm, and the melt temperature is 160~200℃. In step (3), the main motor speed of the TPV dynamic vulcanizing extruder is 400 rpm, and the process parameters include: the temperature of zones one to four is 150~180℃, and the temperature of zone five to the extrusion outlet is 180~220℃. The length-to-diameter ratio (L / D) of the extruder is 52, and multiple sets of kneading blocks are configured in the rear section to provide high shear force.

[0172] Table 1

[0173]

[0174] Table 2

[0175]

[0176] Table 3

[0177]

[0178] Table 4

[0179]

[0180] As can be seen from Tables 3 and 4, the wear-resistant and low compression set container sealing strip provided in Examples 1-9 of this application has excellent comprehensive performance. In particular, by selecting the best reinforcing filler, wear-resistant additives, and crosslinking system, and by using a two-step process with a twin-screw extruder, dynamic vulcanization of phenolic resin and double-sided feeding, precise control of crosslinking is achieved, ensuring the stability and uniformity of material processing. This endows the composite material with high wear resistance, low compression set, high tensile strength, and good processing stability, providing good expansion space for the application of TPV in container sealing strips and making it suitable for replacing traditional EPDM materials.

[0181] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0182] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A composite material, characterized in that, The raw materials for preparing the composite material, by weight percentage, include the following components: 25%~40% EPDM rubber; Polypropylene 10%~20%; Filler oil 20%~40%; Reinforcing filler 5%~12%; Wear-resistant additives 5%~15%; Compatibilizer 2%~5%; Crosslinking agent 2%~4%; Accelerator 0.5%~1.5%; The reinforcing filler includes one or more of reinforcing carbon black and silane coupling agent modified silica masterbatch; The mass ratio of the EPDM rubber to the reinforcing filler is (2~7):

1.

2. The composite material as described in claim 1, characterized in that, The raw materials for preparing the composite material, by weight percentage, include the following components: 25%~35% EPDM rubber; Polypropylene 10%~17%; Filler oil 20%~40%; Reinforcing filler 5%~10%; Wear-resistant additives 10%~15%; Compatibilizer 2%~5%; Crosslinking agent 2%~4%; Accelerator 0.5%~1.5%.

3. The composite material as described in claim 1, characterized in that, The reinforcing carbon black has an oil absorption value of 102 cm⁻¹. 3 / 100g~115 cm 3 / 100g; And / or, the average particle size of the reinforcing carbon black is 26 nm to 30 nm.

4. The composite material according to any one of claims 1 to 3, characterized in that, The Mooney viscosity of the EPDM rubber at 125°C is 60~120; And / or, the ethylene content in the EPDM rubber is 60%~80% by mass; And / or, the ethylene-propylene diene monomer (EPDM) rubber contains 4% to 5% by mass; And / or, the wear-resistant additive includes one or more of polytetrafluoroethylene, modified silicone, and ultra-high molecular weight polyethylene; And / or, the silane coupling agent includes a sulfur-containing silane coupling agent; Optionally, the sulfur-containing silane coupling agent includes one or more of Si69 and Si75.

5. The composite material according to any one of claims 1 to 2, characterized in that, The filler oil includes one or more of white oil and paraffin oil; And / or, the compatibilizer includes one or more of polypropylene grafted maleic anhydride and ethylene propylene diene rubber grafted maleic anhydride. And / or, the crosslinking agent includes octylphenol resin; And / or, the accelerator includes one or more of SnCl2·2H2O, stearic acid, and zinc oxide.

6. The composite material according to any one of claims 1 to 2, characterized in that, The raw materials for preparing the composite material also include additives, which include one or more of lubricants, antioxidants, and light stabilizers; Optionally, the lubricant includes one or more of stearates, polyethylene wax, silicone masterbatch, and fluorinated processing aids; Optionally, the antioxidant includes one or more of antioxidant 1010, antioxidant 1076, and antioxidant 168; Optionally, the light stabilizer includes one or more of benzotriazole UV absorbers, benzophenone UV absorbers, and hindered amine light stabilizers.

7. A method for preparing the composite material according to any one of claims 1 to 6, characterized in that, Includes the following steps: The EPDM rubber, the polypropylene, the reinforcing filler, the wear-resistant additive, the compatibilizer, and the additives are mixed evenly and then extruded to prepare the first intermediate. The filler oil is added to the intermediate, and extrusion granulation is performed to prepare the second intermediate; The crosslinking agent and the accelerator are added to the second intermediate using a two-sided feeding method to perform crosslinking treatment.

8. The method for preparing the composite material as described in claim 7, characterized in that, The reinforcing filler includes reinforcing carbon black and silane coupling agent modified silica masterbatch, and the mass ratio of the reinforcing carbon black to the silane coupling agent modified silica masterbatch is 1:(0.5~1).

9. The method for preparing the composite material as described in claim 8, characterized in that, The wear-resistant additive includes polytetrafluoroethylene and modified silicone, wherein the mass ratio of polytetrafluoroethylene to modified silicone is 1:(0.5~1).

10. A sealing strip, characterized in that, The sealing strip comprises the composite material as described in any one of claims 1 to 6 or the composite material prepared by the method described in any one of claims 7 to 9.

Images