A rubber composition, a method for producing a rubber composition, and a rubber composition

Abstract

The application relates to the technical field of sealing materials, and particularly discloses a rubber compound composition, which comprises the following components in parts by weight: 80-120 parts of ethylene-propylene-diene rubber, 120-150 parts of fast-pressing carbon black, 5-8 parts of zinc oxide, 1-3 parts of stearic acid, 1-1.6 parts of sulfur, 0.8-3 parts of a delayed-action vulcanization accelerator, 1.6-2.1 parts of an ultra-speed vulcanization accelerator and 0.2-0.8 parts of a scorch retarder; the delayed-action vulcanization accelerator is diphenyl bithiazyl disulfide and N-cyclohexyl-2-benzothiazole sulfenamide in a weight ratio of 1:(0.5-3); and the ultra-speed vulcanization accelerator is tetrabenzyl thiuram disulfide, zinc dibutyl dithiocarbamate and tetramethyl thiuram disulfide in a weight ratio of 1:(1-2.5):(0.5-1.5). The rubber compound composition can be used to prepare a low-carbon and light-weight sealing strip with good processing stability and excellent mechanical properties.

Description

Technical Field

[0001] This application relates to the field of sealing materials technology, specifically to a compound rubber composition, an automotive sealing strip, and a method for preparing the same. Background Technology

[0002] Driven by the trends of lightweighting and electrification in the automotive industry, automotive sealing strips are gradually upgrading towards lower density, lower energy consumption, and higher stability. Ethylene propylene diene monomer (EPDM) rubber, due to its excellent weather resistance, aging resistance, and ozone resistance, has become the preferred matrix material for automotive sealing strips. In recent years, to achieve lightweighting, the industry has primarily added thermally expanding microsphere foaming agents to EPDM rubber compounds and prepared low-density sealing strips through in-situ vulcanization foaming. This effectively reduces overall vehicle energy consumption and carbon emissions, meeting the lightweighting requirements of sealing components for new energy vehicles.

[0003] The compounding process for EPDM rubber microsphere foam sealing strips is mainly divided into two-stage and one-stage methods. The two-stage method involves first mastering and then resting the rubber compound before adding the microsphere foaming agent in the final mixing stage. However, this process is lengthy, has a long processing cycle, and involves frequent equipment start-ups and shutdowns, resulting in high energy consumption and carbon emissions per unit product, making it difficult to meet the requirements of automotive companies for efficient and low-carbon production. Furthermore, due to the excessive fluidity and insufficient internal shear force of the rubber compound in the final mixing stage, the microspheres are difficult to disperse fully, leading to frequent microsphere agglomeration, localized enrichment, and uneven dispersion, among other quality issues. The one-stage method, on the other hand, is a continuous operation from feeding and mixing to cooling, completed in one step. It has the advantages of a short preparation cycle and small footprint. However, in actual production, due to the concentrated mixing process and the long heating time of the rubber compound, conventional vulcanization systems are prone to early cross-linking and scorching problems.

[0004] Therefore, developing a compound preparation process and compound with good anti-scorching properties, excellent mechanical properties, and short processing cycle is of great significance for the lightweight, low-cost, and low-carbon development of automobiles. Summary of the Invention

[0005] In order to overcome the problems of scorching, microsphere agglomeration, poor mechanical properties, and long processing cycle in the preparation process of existing rubber compounds, this application provides a rubber compound composition, an automotive sealing strip, and a method for preparing the same.

[0006] In a first aspect, this application provides a compound rubber composition, which adopts the following technical solution: A compound rubber composition comprising the following components in parts by weight: 80-120 parts of EPDM rubber, 120-150 parts of fast-extrusion carbon black, 5-8 parts of zinc oxide, 1-3 parts of stearic acid, 1-1.6 parts of sulfur, 0.8-3 parts of delayed vulcanization accelerator, 1.6-2.1 parts of ultra-fast vulcanization accelerator, and 0.2-0.8 parts of scorching inhibitor; The delayed vulcanization accelerator is dibenzothiazole disulfide and N-cyclohexyl-2-benzothiazole sulfenamide in a weight ratio of 1:(0.5-3). The ultra-fast vulcanization accelerator is tetrabenzylthiuram disulfide, zinc dibutyldithiocarbamate, and tetramethylthiuram disulfide in a weight ratio of 1:(1-2.5):(0.5-1.5).

[0007] This application selects and combines delayed-action vulcanization accelerators, ultra-fast vulcanization accelerators, and anti-scorching agents to synergistically improve the scorch safety, crosslinking uniformity, and product stability of the compound, meeting the requirements of the low-carbon, lightweight one-stage production process for automotive sealing strips. Specifically: First, the anti-scorching agent used in this application can effectively inhibit the formation of active intermediates in the early stage of the vulcanization reaction, prolonging the scorch time of the rubber compound and preventing early crosslinking and scorching during prolonged heating processes such as mixing and filtration. The delayed-action vulcanization accelerator is a compound of dibenzothiazole disulfide and N-cyclohexyl-2-benzothiazole sulfenamide in a specific ratio. This type of accelerator has weak catalytic activity in the low-temperature range of mixing, and will not damage the filler dispersion or prematurely trigger vulcanization; the crosslinking reaction is only started smoothly after the temperature is raised to the shaping vulcanization temperature range, matching the microsphere foaming rate to ensure that foaming and crosslinking occur simultaneously. The accelerated vulcanization accelerator is a compound of tetrabenzylthiuram disulfide, zinc dibutyldithiocarbamate, and tetramethylthiuram disulfide in a specific ratio. These components themselves exhibit extremely high low-temperature activity, and their use alone can easily cause scorching of the rubber compound. Therefore, this application relies on an anti-scorching agent to continuously suppress its inherent high activity during the low-temperature processing stage, fundamentally avoiding the risk of early vulcanization. When entering the high-temperature vulcanization stage, the anti-scorching agent's inhibitory effect becomes ineffective, and the strong catalytic activity of the accelerated accelerator is fully released, rapidly promoting the cross-linking reaction to fully construct a dense and complete rubber cross-linking network, significantly improving the tensile strength, abrasion resistance, and other mechanical properties of the sealing strip. In summary, this application, through the selection and compounding of raw materials in the rubber compound, can significantly improve the processing stability, product appearance uniformity, and mechanical properties of the sealing strip, providing reliable formulation support and an industrial implementation foundation for the preparation of low-carbon, lightweight automotive sealing strips.

[0008] In some embodiments, the weight ratio of dibenzothiazole disulfide to N-cyclohexyl-2-benzothiazole sulfenamide can be 1:(0.5-1.5), 1:(0.5-2), 1:(0.5-2.5), 1:(0.5-3), 1:(1.5-2), 1:(1.5-2.5), 1:(1.5-3), 1:(2-2.5), 1:(2-3), or 1:(2.5-3).

[0009] In one specific embodiment, the weight ratio of dibenzothiazole disulfide to N-cyclohexyl-2-benzothiazole sulfenamide can also be 1:0.5, 1:1.5, 1:2, 1:2.5 or 1:3.

[0010] In some embodiments, the weight ratio of tetrabenzylthiuram disulfide, zinc dibutyldithiocarbamate, and tetramethylthiuram disulfide can be 1:(1-1.5):0.5, 1:(1-2):0.5, 1:(1-2.5):0.5, 1:(1.5-2):0.5, 1:(1.5-2.5):0.5, 1:(2-2.5):0.5, 1:2:(0.5-1), or 1:2:(1-1.5).

[0011] In one specific implementation, the weight ratio of tetrabenzylthiuram disulfide, zinc dibutyldithiocarbamate, and tetramethylthiuram disulfide can also be 1:1:0.5, 1:1.5:0.5, 1:2:0.5, 1:2.5:0.5, 1:2:1, or 1:2:1.5.

[0012] Optionally, the weight ratio of dibenzothiazole disulfide to N-cyclohexyl-2-benzothiazole sulfenamide is 1:(1.5-2.5).

[0013] Optionally, the weight ratio of tetrabenzylthiuram disulfide, zinc dibutyldithiocarbamate, and tetramethylthiuram disulfide is 1:(1.5-2):(0.5-1).

[0014] In this application, the delayed vulcanization accelerator ensures low activity during the mixing temperature rise stage, significantly reducing the risk of early crosslinking and effectively guaranteeing the processing flowability and dispersion stability of the rubber compound during mixing, thin-passing, and filtration processes. The ultra-fast vulcanization accelerator can rapidly increase the crosslinking rate and density during the vulcanization stage, synchronizing the vulcanization process with the microsphere foaming rhythm, avoiding problems such as cell collapse, coarseness, and unevenness due to delayed vulcanization, and failure to foam due to excessively fast vulcanization. This application, by adjusting the component ratios of the two accelerators and further controlling them within the aforementioned range, can significantly extend the scorch time of the rubber compound, improve the safety of continuous production in a single-stage process, and ensure uniform and stable foaming, sufficient vulcanization, and a uniform and dense crosslinking network in the product. This effectively improves the tensile strength and compression set of the sealing strip, giving the compound excellent processing stability, foaming uniformity, and surface appearance. The resulting sealing strip has a smooth surface, is free of particles, exudates, and bubble defects, and exhibits better mechanical and appearance properties, making it more suitable for the low-carbon, lightweight, and high-efficiency continuous production requirements of automotive sealing strips.

[0015] Optionally, the scorching inhibitor is selected from N-cyclohexylthiophthalimide and / or N-tricyclodecylselenophthalimide.

[0016] Optionally, the scorching inhibitor is N-tricyclodecylselenophthalimide.

[0017] This application further selects N-tricyclodecyl selenophthalimide as an anti-scorching agent. The sterically hindered tricyclodecyl group and selenium-nitrogen bond in its molecule can give the compound better scorch stability and vulcanization synergy, making the compound less prone to premature decomposition during internal mixing, thin-passing, filtration and extrusion processing, thereby significantly extending the scorch time, inhibiting early crosslinking and greatly improving processing safety.

[0018] Optionally, the compound rubber composition further comprises 30-50 parts of calcium carbonate, 50-80 parts of paraffin oil, 2-4 parts of polyethylene glycol, 1-3 parts of dispersant, 1-3 parts of microsphere foaming agent, and 5-10 parts of hygroscopic agent.

[0019] In this application, the microsphere foaming agent is a thermally expandable polymer microsphere with an expansion initiation temperature of 150-180℃.

[0020] Secondly, this application provides an automotive sealing strip, which is prepared using a compounded rubber composition.

[0021] Thirdly, this application provides a method for preparing an automotive sealing strip, comprising the following steps: mixing, thin-passing and filtering, extrusion, and vulcanization; The mixing process is as follows: First, all components except sulfur, ultra-fast vulcanization accelerator and microsphere foaming agent are mixed at 60-80℃ and mixed for 80-120s; then, microsphere foaming agent is added and mixed to 100-110℃; finally, sulfur and ultra-fast vulcanization accelerator are added and mixed to 115-120℃ for debinding.

[0022] The method for preparing automotive sealing strips provided in this application adopts a one-stage mixing process. The microsphere foaming agent is added after the main materials have been mixed for a period of time. This timing can utilize the moderate viscosity of the rubber compound and the strong shearing effect of intensive mixing to achieve uniform dispersion of microspheres, thereby eliminating the problem of microsphere agglomeration from the root, improving the homogeneity and stability of the rubber compound, and thus improving the mechanical properties of the sealing strip.

[0023] Optionally, the thin-passing and filtering steps are as follows: the primary rubber obtained from debinding is thin-passed 2-4 times at 40-60℃; then filtered at 80-95℃ using a 60-100 mesh filter.

[0024] Optionally, the extrusion temperature is 70-80°C.

[0025] Optionally, the vulcanization step includes: vulcanizing the extruded rubber strip with microwave hot air at 3-6KW and 250-270℃ to obtain a sealing strip.

[0026] In summary, this application has the following beneficial effects: 1. This application provides a compound rubber composition that uses dibenzothiazole disulfide and N-cyclohexyl-2-benzothiazole sulfenamide in a weight ratio of 1:(0.5-3) as delayed vulcanization accelerators, and tetrabenzylthiuram disulfide, zinc dibutyldithiocarbamate, and tetramethylthiuram disulfide in a weight ratio of 1:(1-2.5):(0.5-1.5) as ultra-fast vulcanization accelerators. This results in a synergistic improvement in scorch safety, foaming uniformity, crosslinking uniformity, and product stability of the compound rubber, meeting the requirements of the low-carbon and lightweight one-stage production process for automotive sealing strips.

[0027] 2. This application further controls the weight ratio of dibenzothiazole disulfide and N-cyclohexyl-2-benzothiazole sulfenamide in the delayed curing accelerator to be in the range of 1:(1.5-2.5), and the weight ratio of tetrabenzylthiuram disulfide, zinc dibutyldithiocarbamate and tetramethylthiuram disulfide to be in the range of 1:(1.5-2):(0.5-1). The resulting sealant has a smooth surface, is free of particles, exudation, and bubble defects, and has better mechanical and appearance properties. Its Mooney scorch t5 is ≥10min, tensile strength is ≥12MPa, compression set is <10% at (23±2)℃×72h, and compression set is <16% at (70±1)℃×24h, which is more suitable for the low-carbon, lightweight, and high-efficiency continuous production requirements of automotive sealing strips.

[0028] 3. This application further uses N-tricyclodecylselenophthalimide as an anti-scorching agent, which can significantly prolong the scorching time, inhibit early crosslinking, and greatly improve processing safety; and can also optimize and improve mechanical properties to a certain extent. The Mooney scorching t5 of the obtained automotive sealing strip can reach 15.2 min, the tensile strength is as high as 14.1 MPa, the compression set at (23±2)℃×72h is only 7.2%, and the compression set at (70±1)℃×24h is only 13.1%. Detailed Implementation

[0029] This application provides a compound rubber composition comprising the following components in parts by weight: 80-120 parts of EPDM rubber, 120-150 parts of fast-extrusion carbon black, 5-8 parts of zinc oxide, 1-3 parts of stearic acid, 1-1.6 parts of sulfur, 0.8-3 parts of delayed vulcanization accelerator, 1.6-2.1 parts of ultra-fast vulcanization accelerator, 0.2-0.8 parts of scorching inhibitor, 30-50 parts of calcium carbonate, 50-80 parts of paraffin oil, 2-4 parts of polyethylene glycol, 1-3 parts of dispersant, 1-3 parts of microsphere foaming agent, and 5-10 parts of hygroscopic agent. The delayed vulcanization accelerator is dibenzothiazole disulfide and N-cyclohexyl-2-benzothiazole sulfenamide in a weight ratio of 1:(0.5-3); the ultra-fast vulcanization accelerator is tetrabenzylthiuram disulfide, zinc dibutyldithiocarbamate and tetramethylthiuram disulfide in a weight ratio of 1:(1-2.5):(0.5-1.5); and the scorching inhibitor is N-cyclohexylthiophthalimide.

[0030] This application provides a method for preparing an automotive sealing strip, comprising the following steps: (1) Mixing: Weigh each component according to the weight parts of the compound rubber composition. Add the components other than sulfur, ultra-fast vulcanization accelerator and microsphere foaming agent to a mixer at 60-80℃ and mix for 80-120s. Then raise the top plug. Then add microsphere foaming agent to the mixer and mix to 100-110℃. Raise the top plug and clean it. Then add sulfur and ultra-fast vulcanization accelerator to the mixer and mix to 115-120℃ to discharge the rubber and obtain the primary rubber. (2) Thin pass and filtration: Transfer the primary rubber compound to a two-roll mill and pass it through a thin pass 2-4 times at 40-60℃. The distance between the two rolls of the two-roll mill is 0.5-1mm, and the roll speed is 15-25r / min. Then send it to a gear pump filter and filter it with a 60-100 mesh metal filter at 80-95℃. After cooling and packaging, the finished compound is obtained. The storage temperature of the finished compound is 20-25℃ and the relative humidity is 40-60%. (3) Extrusion: The finished compound rubber is fed into a single screw extruder and extruded at 70-80℃ to obtain rubber strips; (4) Curing: The rubber strip is put into a microwave hot air curing box online and cured by microwave hot air at 3-6KW and 250-270℃ to obtain the sealing strip.

[0031] In this embodiment, the EPDM rubber was purchased from Arlanx Newco High Performance Elastomers (Changzhou) Co., Ltd.; the fast-extrusion carbon black was purchased from Orion Engineering Carbon (Qingdao) Co., Ltd., model N550; the dispersant was purchased from Rhein Chemicals (Qingdao) Co., Ltd., model AFLUX-42M; the foaming agent was 4600FSS, purchased from Dongjin Semeken Co., Ltd. of South Korea; and the hygroscopic agent was calcium oxide. All raw materials, reagents, solvents, etc. used in this application can be obtained commercially.

[0032] The present application will be further described in detail below with reference to embodiments and performance testing. Examples 1-10

[0033] Examples 1-10 each provide a sealing strip.

[0034] The difference in the above embodiments is that the specific composition ratio of the delayed vulcanization accelerator and the ultra-fast vulcanization accelerator is shown in Table 1 below.

[0035] The method for preparing the sealing strip provided in Examples 1-10 includes the following steps: (1) Mixing: Weigh the following components according to their weight proportions in the compound: 100g EPDM rubber, 130g fast-extrusion carbon black, 7g zinc oxide, 2g stearic acid, 1.3g sulfur, 2g delayed vulcanization accelerator, 1.8g ultra-fast vulcanization accelerator, 0.5g scorch inhibitor (N-cyclohexylthiophthalimide), 40g calcium carbonate, 60g paraffin oil, 3g polyethylene glycol, 2g dispersant, and thermal expansion agent. 2g of thermally expandable polymer microspheres and 8g of hygroscopic agent were added to a 70°C internal mixer, except for sulfur, ultra-fast vulcanization accelerator and thermally expandable polymer microspheres. The mixture was mixed for 100s and the top plug was raised. Then, thermally expandable polymer microspheres were added to the internal mixer and mixed to 105°C. The top plug was raised and cleaned. Then, sulfur and ultra-fast vulcanization accelerator were added to the internal mixer and mixed to 118°C to discharge the rubber, thus obtaining the initial rubber. (2) Thin pass and filtration: The primary rubber compound is transferred to a two-roll mill and thinly passed 3 times at 50°C. The distance between the two rolls of the two-roll mill is 1 mm, and the roll speed is 20 r / min. Then it is sent to a gear pump filter and filtered at 90°C using a 100-mesh metal filter screen. After cooling and packaging, the finished rubber compound is obtained. The storage temperature of the finished rubber compound is 25°C and the relative humidity is 50%. (3) Extrusion: The finished compound rubber is fed into a single screw extruder and extruded at 75°C to obtain rubber strips; (4) Curing: The rubber strip is put into a microwave hot air curing box online and cured by microwave hot air at 4KW and 260℃ to obtain the sealing strip.

[0036] Table 1. Specific components and proportions of the delayed-release and ultra-fast vulcanization accelerators used in Examples 1-10. Example 11

[0037] Example 11 provides a sealing strip.

[0038] The difference between the above embodiments and Embodiment 3 is that the scorching inhibitor is replaced with N-tricyclodecylselenophthalimide; The preparation method of N-tricyclodecylselenophthalimide is as follows: (1) Preparation of tricyclic decylselenool: Under nitrogen protection, 0.10 mol of selenium powder and 100 mL of anhydrous toluene were added to a dry reaction flask and stirred to disperse. The temperature was slowly raised to 55 °C, and 0.10 mol of 1-adamanthiol (CAS No. 34301-54-7) was added dropwise. The reaction was maintained at this temperature for 1 h until the selenium powder was completely reacted to generate the tricyclic decylselenool intermediate. Subsequently, the system was cooled to 35 °C, and 0.10 mol of N-chlorosuccinimide was slowly added in batches. The temperature was kept below 40 °C and the reaction was maintained at this temperature for 1.5 h. The reaction generated stable tricyclic decylselenochloride. The reaction solution was used directly in the next step without separation.

[0039] (2) Add 0.105 mol phthalimide and 80 mL anhydrous DMF to another dry reaction flask, add 0.105 mol sodium methoxide under stirring, react at room temperature for 30 min to obtain a sodium phthalimide salt suspension; slowly drop the above sodium phthalimide salt into the tricyclic decyl selenide monochloride prepared in step (1), control the dropping temperature to about 5℃, raise the temperature to 25℃ after dropping to react for 3 h, and monitor the reaction to be complete by TLC; after the reaction is completed, filter to remove sodium chloride solid, wash the filtrate with saturated brine and deionized water in sequence, dry with anhydrous sodium sulfate, remove the solvent under reduced pressure, recrystallize with ethyl acetate / petroleum ether mixed solvent to obtain the pale yellow solid product N-tricyclic decyl selenide phthalimide. Comparative Example 1

[0040] Comparative Example 1 provides a sealing strip.

[0041] The difference between the above comparative example and Example 3 is that the delayed vulcanization accelerator is dibenzothiazole disulfide. Comparative Example 2

[0042] Comparative Example 2 provides a sealing strip.

[0043] The difference between the above comparative example and Example 3 is that the delayed vulcanization accelerator is N-cyclohexyl-2-benzothiazole sulfenamide. Comparative Example 3

[0044] Comparative Example 3 provides a sealing strip.

[0045] The difference between the above comparative example and Example 3 is that the ultra-fast vulcanization accelerator is tetrabenzylthiuram disulfide and tetramethylthiuram disulfide in a weight ratio of 1:2.5. Comparative Example 4

[0046] Comparative Example 4 provides a sealing strip.

[0047] The difference between the above comparative example and Example 3 is that the ultra-fast vulcanization accelerator is tetrabenzylthiuram disulfide and zinc dibutyldithiocarbamate in a weight ratio of 1:2.5. Comparative Example 5

[0048] Comparative Example 5 provides a sealing strip.

[0049] The difference between the above comparative example and Example 3 is that the ultra-fast vulcanization accelerator is zinc dibutyldithiocarbamate and tetramethylthiuram disulfide in a weight ratio of 2.5:1. Performance testing

[0050] Test strips were prepared according to the methods of Examples 1-11 and Comparative Examples 1-5, and various performance tests were performed. The results are shown in Table 2 below.

[0051] (1) Mooney scorch: The scorch time t5 of the test strip at 125℃ was detected by using an MV-3000AC Mooney viscometer scorch tester; (2) Tensile strength: The tensile strength of the rubber strip shall be tested in accordance with GB / T 528-2009; (3) Compression set: The compression set of the test strip under two specified conditions was tested in accordance with GB / T 7759 "Determination of compression set of vulcanized rubber or thermoplastic rubber".

[0052] Table 2 Performance test results of the test strips obtained in Examples 1-11 and Comparative Examples 1-5

[0053] According to the test results in Table 2, Examples 1-11 used dibenzothiazole disulfide and N-cyclohexyl-2-benzothiazole sulfenamide in a weight ratio of 1:(0.5-3) as delayed vulcanization accelerators, and tetrabenzylthiuram disulfide, zinc dibutyldithiocarbamate and tetramethylthiuram disulfide in a weight ratio of 1:(1-2.5):(0.5-1.5) as ultra-fast vulcanization accelerators. The obtained test strips had good mechanical and appearance properties, with Mooney scorch t5 ≥ 7 min, tensile strength ≥ 10 MPa, compression set < 13% at (23±2)℃×72h, and compression set < 19% at (70±1)℃×24h. This meets the requirements of low-carbon, lightweight, and high-efficiency continuous production of automotive sealing strips. Comparative Examples 1-2 used only dibenzothiazole disulfide or N-cyclohexyl-2-benzothiazole sulfenamide as delayed vulcanization accelerators, resulting in test rubber strips with a Mooney scorch t5 of only 5.4-5.9 min, tensile strength of only 9.5-10.1 MPa, and compression set at (23±2)℃×72h as high as 16.9-17.8%, and compression set at (70±1)℃×24h as high as 28.3-29.9%. Comparative Examples 3-5 used tetrabenzylthiuram disulfide and tetrabenzylthiuram disulfide in a weight ratio of 1:2.5. Using methyl thiuram, tetrabenzyl thiuram disulfide and zinc dibutyl dithiocarbamate in a weight ratio of 1:2.5 or zinc dibutyl dithiocarbamate and tetramethyl thiuram disulfide in a weight ratio of 2.5:1 as ultra-fast vulcanization accelerators, the Mooney scorch t5 of the test rubber strips was 12.4-13.2 min, the tensile strength was only 7.1-8.4 MPa, the compression set at (23±2)℃×72h was as high as 22.5-29.6%, and the compression set at (70±1)℃×24h was as high as 36.7-45.2%.

[0054] Further comparison revealed that the test strips obtained in Examples 2-4, 7, and 9 exhibited Mooney scorch t5 ≥ 10 min, tensile strength ≥ 12 MPa, compression set < 10% at (23±2)℃ for 72 h, and compression set < 16% at (70±1)℃ for 24 h. Therefore, it is evident that this application further utilizes dibenzothiazole disulfide and N-cyclohexyl-2-benzothiazole sulfenamide in a weight ratio of 1:(1.5-2.5) as delayed-action vulcanization accelerators, and tetrabenzylthiuram disulfide, zinc dibutyldithiocarbamate, and tetramethylthiuram disulfide in a weight ratio of 1:(1.5-2):(0.5-1) as ultra-fast vulcanization accelerators, resulting in strips with superior overall performance.

[0055] In summary, this application employs specific anti-scorching agents and accelerators, which can achieve a synergistic improvement in ultra-long scorching time, excellent mechanical properties, and low compression set. This effectively solves the problem of balancing processing safety and vulcanization effect in traditional sealing strips, providing a brand-new solution for the low-carbon, efficient, and high-quality production of high-end automotive sealing strips.

[0056] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A compound rubber composition, characterized in that, The product comprises the following components in parts by weight: 80-120 parts EPDM rubber, 120-150 parts fast-extrusion carbon black, 5-8 parts zinc oxide, 1-3 parts stearic acid, 1-1.6 parts sulfur, 0.8-3 parts delayed vulcanization accelerator, 1.6-2.1 parts ultra-fast vulcanization accelerator, and 0.2-0.8 parts scorching inhibitor; The delayed vulcanization accelerator is dibenzothiazole disulfide and N-cyclohexyl-2-benzothiazole sulfenamide in a weight ratio of 1:(0.5-3). The ultra-fast vulcanization accelerator is tetrabenzylthiuram disulfide, zinc dibutyldithiocarbamate, and tetramethylthiuram disulfide in a weight ratio of 1:(1-2.5):(0.5-1.5).

2. The compound rubber composition according to claim 1, characterized in that, The weight ratio of dibenzothiazole disulfide to N-cyclohexyl-2-benzothiazole sulfenamide is 1:(1.5-2.5).

3. The compound rubber composition according to claim 1, characterized in that, The weight ratio of tetrabenzylthiuram disulfide, zinc dibutyldithiocarbamate, and tetramethylthiuram disulfide is 1:(1.5-2):(0.5-1).

4. The compound rubber composition according to claim 1, characterized in that, The scorching inhibitor is selected from N-cyclohexylthiophthalimide and / or N-tricyclodecylselenophthalimide.

5. The compound rubber composition according to any one of claims 1-4, characterized in that, The compound rubber composition also contains 30-50 parts of calcium carbonate, 50-80 parts of paraffin oil, 2-4 parts of polyethylene glycol, 1-3 parts of dispersant, 1-3 parts of microsphere foaming agent, and 5-10 parts of hygroscopic agent.

6. A car sealing strip, characterized in that, It is prepared using the compound rubber composition according to any one of claims 1-5.

7. The method for preparing an automotive sealing strip as described in claim 6, characterized in that, Includes the following steps: Mixing, thin-pass filtering, extrusion, vulcanization; The mixing process is as follows: First, all components except sulfur, ultra-fast vulcanization accelerator and microsphere foaming agent are mixed at 60-80℃ and mixed for 80-120s; then, microsphere foaming agent is added and mixed to 100-110℃; finally, sulfur and ultra-fast vulcanization accelerator are added and mixed to 115-120℃ for debinding.

8. The method for preparing an automotive sealing strip according to claim 7, characterized in that, The thin-passing and filtration steps are as follows: the primary rubber obtained from debinding is thin-passed 2-4 times at 40-60℃; then filtered at 80-95℃ using a 60-100 mesh filter.

9. The method for preparing an automotive sealing strip according to claim 7, characterized in that, The extrusion temperature is 70-80℃.

10. The method for preparing an automotive sealing strip according to claim 7, characterized in that, The vulcanization step includes: vulcanizing the extruded rubber strip with microwave hot air at 3-6KW and 250-270℃ to obtain a sealing strip.

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