A sidewall rubber composition and a method for producing the same

Abstract

The application provides a kind of sidewall rubber composition and its preparation method, belong to rubber material technical field, sidewall rubber composition includes the following components by weight parts: base rubber 100 parts, the base rubber is composed of 72-88 parts functionalized polybutadiene rubber and 12-28 parts terminal mercapto liquid polyisoprene;4-vinylpyridine 0.5-2.0 parts;Resin containing ester group 10-16 parts;Reinforcing agent 35-50 parts;Vulcanization system 2.3-4.3 parts.The application of each raw material is mutually synergistic, significantly improves the fatigue resistance, effectively inhibits the expansion of microcracks, significantly prolongs the fatigue life of the material, and at the same time improves the ozone cracking resistance and durability.

Description

Technical Field

[0001] This invention relates to the field of rubber materials technology, and more specifically to a sidewall rubber composition and its preparation method. Background Technology

[0002] As a critical part directly exposed to the external environment, the tire sidewall is subjected to the combined effects of high temperature, ozone, ultraviolet rays and high torque dynamic loads for a long time, making it prone to cracking, fatigue failure and premature aging, which seriously affects tire service life and driving safety. Especially in the era of electric vehicles (EVs), their high torque and high load characteristics place more stringent requirements on the dynamic performance of the sidewall rubber.

[0003] Existing technologies typically rely on adding static antioxidants or anti-aging agents to the rubber matrix to achieve protection. For example, patent publication number CN120484352A mainly relies on the synergistic static antioxidant effect of 1-phenyl-3-methyl-5-pyrazolone and D-α-tocopherol. While some solutions can improve anti-aging performance to a certain extent, they still have the following prominent drawbacks: (1) It only provides static protection and cannot achieve dynamic self-repair. Under the instantaneous impact of high torque in electric vehicles, microcracks are prone to rapid expansion. (2) It has limited long-term protection against ozone cracking and is difficult to meet the durability requirements of electric vehicles under high speed and high load scenarios.

[0004] Existing technologies are mostly limited to traditional antioxidants or simple functional modifications, and no publicly available solution has yet emerged that simultaneously addresses tire sidewall dynamic fatigue, self-healing, and ozone cracking. Therefore, further improvements and development are still needed. Summary of the Invention

[0005] To address the shortcomings of existing technologies and solve the aforementioned problems, a sidewall rubber composition and its preparation method are proposed, and the following technical solution is provided: A sidewall rubber composition comprising, by weight, the following components: 100 parts of a matrix rubber, said matrix rubber being composed of 72-88 parts of functionalized polybutadiene rubber and 12-28 parts of mercapto-terminated liquid polyisoprene; 0.5-2.0 parts of 4-vinylpyridine; 10-16 parts of a resin containing ester groups; 35-50 parts of a reinforcing agent; and 2.3-4.3 parts of a vulcanization system.

[0006] Furthermore, the functionalized polybutadiene rubber is a polybutadiene rubber with sulfur-nitrogen bond functional groups introduced into the end groups.

[0007] Furthermore, the number-average molecular weight of the terminal thiol-terminated liquid polyisoprene is 900-2200.

[0008] The mass ratio of the functionalized polybutadiene rubber to the mercapto-terminated liquid polyisoprene is (4.5-7.0):1.

[0009] Furthermore, the reinforcing agent is silica, and the resin containing ester groups is selected from at least one of hydrogenated rosin esters and terpene phenolic resins.

[0010] Furthermore, the vulcanization system comprises: 1.5-2.5 parts sulfur and 0.8-1.8 parts accelerator.

[0011] Furthermore, the preparation method of the functionalized polybutadiene rubber is as follows: under nitrogen protection, 1,3-butadiene is dissolved in a non-polar solvent for anionic polymerization reaction, and then a thiourea compound is added to continue the reaction to obtain the functionalized polybutadiene rubber.

[0012] This application also provides a method for preparing the above-mentioned sidewall rubber composition, the method being as follows: (1) First stage of intensive mixing: Functionalized polybutadiene rubber, mercapto-terminated liquid polyisoprene, ester-containing resin and reinforcing agent are mixed to obtain a first stage of compound; (2) Two-stage mixing: 4-vinylpyridine and vulcanization system are added to the first-stage compound, and the compound is further mixed to obtain the second-stage compound; (3) Vulcanization: The two-stage compound rubber is vulcanized to obtain the sidewall rubber composition.

[0013] Furthermore, in step (1), the temperature of the first stage of intensive mixing is 150-160℃, and the mixing time is 8-12 minutes.

[0014] Furthermore, the 4-vinylpyridine is added in step (2), and the mixture is continued for 1-3 minutes after addition.

[0015] Due to the adoption of the above technical solutions, the beneficial technical effects of the present invention are as follows: 1. This invention significantly improves fatigue resistance: The functionalized polybutadiene rubber forms reversible coordination bonds with the pyridine groups of 4-vinylpyridine, which can break and absorb impact energy under stress; the ester-containing resin guides the orderly rearrangement of the network through conformational adjustment, avoiding stress concentration; and the terminal thiol-containing liquid polyisoprene can rapidly repair the fractured interface after stress relief. This triple synergistic mechanism effectively inhibits the propagation of microcracks, significantly extending the fatigue life of the material. 2. This invention improves the resistance to ozone cracking and durability. The micro-damage to the surface of the material caused by ozone attack can be repaired to a certain extent, delaying the generation and development of cracks, thereby improving the service life and safety of tires in harsh environments. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application.

[0017] A sidewall rubber composition comprises, by weight, the following components: 100 parts of a matrix rubber, wherein the matrix rubber is composed of 72-88 parts of functionalized polybutadiene rubber and 12-28 parts of mercapto-terminated liquid polyisoprene; 0.5-2.0 parts of 4-vinylpyridine; 10-16 parts of an ester-containing resin; 35-50 parts of a reinforcing agent; and 2.3-4.3 parts of a vulcanization system. These four core components—functionalized polybutadiene rubber, mercapto-terminated liquid polyisoprene, 4-vinylpyridine, and ester-containing resin—and their specific proportions together constitute the basic framework for achieving dynamic self-healing functionality. Through the interaction of different components at the molecular level, a multi-layered dynamic reversible network is constructed. This basic combination solves the problem that traditional sidewall rubbers cannot inhibit the propagation of microcracks after their formation, thereby fundamentally improving the durability and safety of the material.

[0018] The functionalized polybutadiene rubber described is a polybutadiene rubber with sulfur-nitrogen bond functional groups introduced into its end groups. These sulfur-nitrogen bond functional groups can reversibly coordinate with the pyridine ring of the subsequently added 4-vinylpyridine. When the material is subjected to external impact, these lower-energy coordination bonds preferentially break, effectively absorbing and dissipating impact energy and preventing the breakage of the covalent backbone. After stress relief, these coordination bonds spontaneously reform, completing the first level of rapid repair. By introducing these reversible "sacrificial bonds," the problem of traditional rubber networks only being able to release energy through backbone breakage under stress, leading to permanent damage, is solved, significantly improving the material's impact resistance.

[0019] The number-average molecular weight of the terminal thiol-terminated liquid polyisoprene is 900-2200. If the molecular weight is below 900, its final performance may be affected due to excessive volatility or poor compatibility with the matrix; if the molecular weight is above 2200, its viscosity is too high, its fluidity decreases, and it will not be able to quickly migrate to the crack tip for repair after the network is damaged. Therefore, by controlling the molecular weight within the range of 900-2200, it can both act as a flexible chain segment inserted into the network and quickly fill the gaps when microcracks are generated due to its excellent fluidity. The terminal thiol functional groups can react with the broken chain ends or active sites to achieve chemical "stitching" of the interface, which solves the problem of slow repair speed and low efficiency of dynamic networks after fracture and realizes the second level of interface repair.

[0020] In the rubber composition, the reinforcing agent is silica; the resin containing ester groups is selected from at least one of hydrogenated rosin esters and terpene phenolic resins. Silica is chosen as the reinforcing agent because its surface silanol groups can form hydrogen bonds with functionalized polymers and other polar components, constructing a physical cross-linked network. This not only enhances the static mechanical properties of the material but also helps form an energy-dissipating interfacial layer. Hydrogenated rosin esters or terpene phenolic resins are chosen because the ester groups in these resins have moderate polarity and steric hindrance, enabling them to adjust their molecular conformation under stress, guiding the polymer chain segments to rearrange orderly along the stress direction, thereby uniformly dispersing stress and avoiding stress concentration. Through these preferred auxiliary components, the performance of the dynamic network is further optimized, achieving a synergistic effect of mechanical reinforcement and dynamic repair.

[0021] The components of this application form a synergistic reinforcing effect. The reversible coordination network composed of sulfur-nitrogen bonds and pyridine groups is responsible for absorbing transient impacts, while liquid polyisoprene of a specific molecular weight is responsible for repairing interfacial damage. Silica and a specific resin jointly optimize the network's mechanical response and stress dispersion. This combination significantly improves the material's overall performance, especially its fatigue resistance, solving the problem of limited effectiveness of single improvement measures.

[0022] Specifically, the amounts of each component are as follows: 80 parts functionalized polybutadiene rubber; 20 parts mercapto-terminated liquid polyisoprene; 1.2 parts 4-vinylpyridine; 13 parts hydrogenated rosin ester; 42 parts silica; 2.0 parts sulfur; and 1.3 parts accelerator. This is an optimized formulation that has been developed through extensive experimentation.

[0023] The preparation method of the functionalized polybutadiene rubber is as follows: under nitrogen protection, 1,3-butadiene is dissolved in a non-polar solvent for anionic polymerization reaction, and then a thiourea compound is added to continue the reaction to obtain the functionalized polybutadiene rubber.

[0024] This application also provides a method for preparing a sidewall rubber. The method includes a first-stage mixing step, a second-stage mixing step, and a vulcanization step. First, in the first-stage mixing step, functionalized polybutadiene rubber, mercapto-terminated liquid polyisoprene, an ester-containing resin, and a reinforcing agent are mixed to obtain a first-stage compound. Subsequently, in the second-stage mixing step, 4-vinylpyridine and a vulcanization system containing sulfur and an accelerator are added to the first-stage compound, and mixing continues to obtain a second-stage compound. Finally, in the vulcanization step, the second-stage compound is vulcanized to obtain the final sidewall rubber. This two-stage feeding sequence avoids premature reaction of the active components, ensuring the effective functioning of each component.

[0025] In step (1), the temperature of the first-stage mixing is 150-160℃, and the mixing time is 8-12 minutes. In step (2), after adding the 4-vinylpyridine, mixing continues for 1-3 minutes. Limiting the temperature and time of the first-stage mixing ensures the full dispersion and wetting of the raw materials at high temperatures, forming a uniform masterbatch, which is fundamental to guaranteeing the physical properties of the final product. In the second-stage mixing, 4-vinylpyridine is added at a lower temperature and mixed for a short time to ensure its uniform dispersion in the matrix without or with minimal coordination reactions, creating conditions for subsequent interaction with sulfur-nitrogen functional groups. Precise control of process parameters solves the technical problem of dynamic network construction failure due to uneven mixing or premature reaction, ensuring that the excellent performance in the laboratory can be stably reproduced in industrial production.

[0026] Functionalized polybutadiene rubber serves as the main framework of the network, providing fundamental mechanical strength and elasticity. Thiol-terminated liquid polyisoprene acts as a highly fluid restorative agent, interspersed within the main network. 4-Vinylpyridine is responsible for forming reversible connections with the functionalized polybutadiene rubber. Ester-containing resins guide the ordered slippage and rearrangement of polymer chains under stress, thereby effectively dispersing stress. Reinforcing agents enhance the overall macroscopic mechanical properties of the composite material, such as hardness and abrasion resistance.

[0027] First, the functionalized polybutadiene rubber was prepared. In a 5-liter, jacketed reactor equipped with a stirrer, 2000 mL of cyclohexane was added as a solvent under nitrogen protection, followed by 1000 g of 1,3-butadiene monomer. After cooling the reaction system to 30°C, 20 mmol of n-butyllithium initiator was added dropwise, and the polymerization reaction was carried out at a temperature below 50°C for 3 hours. Then, 22 mmol of N,N-dimethylthiourea was added as a capping agent, and the reaction was continued at 60°C for 2 hours to introduce sulfur-nitrogen functional groups at the ends of the polybutadiene chains. After the reaction, the polymer solution was poured into a large amount of methanol for precipitation. The polymer was collected by filtration and washed several times with methanol. Finally, the resulting white elastic solid was dried in a vacuum oven at 60°C for 24 hours to obtain the desired functionalized polybutadiene rubber.

[0028] In the following examples and comparative examples: The thiol-terminated liquid polyisoprene was sourced from Qingdao Ruida Chemical Co., Ltd.; 4-vinylpyridine was sourced from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0029] Example 1 Preparation of sidewall rubber composition.

[0030] The formula, by weight, is as follows: 80 parts functionalized polybutadiene rubber, 20 parts terminal thiol liquid polyisoprene with a number average molecular weight of 1500, 13 parts hydrogenated rosin ester, 42 parts silica, 1.2 parts 4-vinylpyridine, 2.0 parts sulfur, and 1.3 parts accelerator CZ (N-cyclohexyl-2-benzothiazole sulfenamide).

[0031] The preparation process strictly follows a two-stage mixing process. First, a single-stage internal mixing is performed: functionalized polybutadiene rubber, mercapto-terminated liquid polyisoprene, and hydrogenated rosin ester are added to a Hacker internal mixer and plasticized for 2 minutes at 60 rpm and an initial temperature of 100°C to soften the rubber. Then, silica is added in batches while the temperature of the mixing chamber is raised to 155°C, and the mixture is vigorously mixed for 10 minutes under these conditions to ensure complete dispersion of the silica. After completion, the mixture is discharged to obtain the first-stage compound. This compound is pressed into sheets on an open mill and thoroughly cooled to room temperature. A second-stage internal mixing is then performed: the cooled first-stage compound is returned to the internal mixer, and 4-vinylpyridine is added first at 60 rpm and a temperature of 80°C, and mixed for 2 minutes to achieve uniform dispersion. Next, sulfur and accelerator CZ are added, and mixing continues for 3 minutes. After completion, the mixture is discharged to obtain the final two-stage compound. Finally, the two-stage compound was placed on a flat vulcanizing machine at 160℃ and 15MPa and vulcanized in a mold for 20 minutes to obtain a vulcanized rubber sheet with a thickness of 2 mm, which was used for subsequent performance testing.

[0032] Example 2 Preparation of sidewall rubber composition.

[0033] Its formula, by weight, is as follows: 72 parts functionalized polybutadiene rubber, 28 parts terminal mercapto liquid polyisoprene (Mn=1000), 10 parts terpene phenolic resin, 35 parts fumed silica, 0.5 parts 4-vinylpyridine, 1.5 parts sulfur, and 0.8 parts accelerator D.

[0034] The preparation process is the same as in Example 1.

[0035] Example 3 Its formula, by weight, is as follows: 88 parts functionalized polybutadiene rubber, 12 parts terminal mercapto liquid polyisoprene (Mn=2200), 16 parts hydrogenated rosin ester, 50 parts silica, 2.0 parts 4-vinylpyridine, 2.5 parts sulfur, and 1.8 parts accelerator M (2-mercaptobenzothiazole).

[0036] The preparation process strictly follows a two-stage mixing process. First, a single-stage internal mixing is performed: functionalized polybutadiene rubber, mercapto-terminated liquid polyisoprene, and hydrogenated rosin ester are added to a Hacker internal mixer and plasticized for 2 minutes at 60 rpm and an initial temperature of 100°C to soften the rubber. Then, silica is added in batches while the temperature of the mixing chamber is raised to 150°C, and the mixture is vigorously mixed for 8 minutes under these conditions to ensure complete dispersion of the silica. After completion, the mixture is discharged to obtain the first-stage compound. This compound is pressed into sheets on an open mill and thoroughly cooled to room temperature. A second-stage internal mixing is then performed: the cooled first-stage compound is returned to the internal mixer, and 4-vinylpyridine is added first at 60 rpm and a temperature of 80°C, and mixed for 1 minute to ensure uniform dispersion. Next, sulfur and accelerator CZ are added, and mixing continues for 3 minutes. After completion, the mixture is discharged to obtain the final two-stage compound. Finally, the two-stage compound was placed on a flat vulcanizing machine at 160℃ and 15MPa and vulcanized in a mold for 20 minutes to obtain a vulcanized rubber sheet with a thickness of 2 mm, which was used for subsequent performance testing.

[0037] Comparative Example 1 Its formula, by weight, is as follows: 70 parts natural rubber, 30 parts butadiene rubber, 50 parts carbon black N550, 8 parts aromatic oil, 2.0 parts antioxidant 4010NA, 1.5 parts sulfur, and 1.0 part accelerator CZ.

[0038] The preparation process strictly follows a two-stage mixing process. First, a single-stage internal mixing is performed: butadiene rubber and natural rubber are added to a Hacker internal mixer and plasticized for 2 minutes at 60 rpm and an initial temperature of 100°C to soften the rubber. Then, carbon black, aromatic oil, and antioxidant 4010NA are added in batches, while the temperature of the mixing chamber is raised to 155°C. Under these conditions, the mixture is vigorously mixed for 10 minutes to ensure complete dispersion of the carbon black. After completion, the rubber is discharged, yielding the first-stage compound. This compound is pressed into sheets on an open mill and thoroughly cooled to room temperature. A second-stage internal mixing is then performed: the cooled first-stage compound is returned to the internal mixer, and sulfur and accelerator CZ are added at 60 rpm and a temperature of 80°C. The mixture is then further mixed for 3 minutes. After completion, the rubber is discharged, yielding the final two-stage compound. Finally, the two-stage compound was placed on a flat vulcanizing machine at 160℃ and 15MPa and vulcanized in a mold for 20 minutes to obtain a vulcanized rubber sheet with a thickness of 2 mm, which was used for subsequent performance testing.

[0039] Comparative Example 2 Its formula, by weight, is as follows: 80 parts functionalized polybutadiene rubber, 20 parts terminal mercapto liquid polyisoprene with a number average molecular weight of 1500, 13 parts hydrogenated rosin ester, 42 parts fumed silica, 2.0 parts sulfur, and 1.3 parts accelerator CZ (N-cyclohexyl-2-benzothiazole sulfenamide).

[0040] The preparation process strictly follows a two-stage mixing process. First, a single-stage internal mixing is performed: functionalized polybutadiene rubber, mercapto-terminated liquid polyisoprene, and hydrogenated rosin ester are added to a Hacker internal mixer and plasticized for 2 minutes at 60 rpm and an initial temperature of 100°C to soften the rubber. Then, silica is added in batches while the temperature of the mixing chamber is raised to 155°C, and the mixture is vigorously mixed for 10 minutes under these conditions to ensure complete dispersion of the silica. After completion, the mixture is discharged to obtain the first-stage compound. This compound is pressed into sheets on a two-roll mill and thoroughly cooled to room temperature. A second-stage internal mixing is then performed: the cooled first-stage compound is returned to the internal mixer, and sulfur and accelerator CZ are added at 60 rpm and a temperature of 80°C, and mixing continues for 3 minutes. After completion, the mixture is discharged to obtain the final two-stage compound. Finally, the two-stage compound was placed on a flat vulcanizing machine at 160℃ and 15MPa and vulcanized in a mold for 20 minutes to obtain a vulcanized rubber sheet with a thickness of 2 mm, which was used for subsequent performance testing.

[0041] Comparative Example 3 Its formula, by weight, is as follows: 100 parts functionalized polybutadiene rubber, 13 parts hydrogenated rosin ester, 42 parts silica, 1.2 parts 4-vinylpyridine, 2.0 parts sulfur, and 1.3 parts accelerator CZ (N-cyclohexyl-2-benzothiazole sulfenamide).

[0042] The preparation process strictly follows a two-stage mixing process. First, a single-stage internal mixing is performed: functionalized polybutadiene rubber and hydrogenated rosin ester are added to a Hacker internal mixer and plasticized for 2 minutes at 60 rpm and an initial temperature of 100°C to soften the rubber. Then, silica is added in batches while the temperature of the mixing chamber is raised to 155°C, and the mixture is vigorously mixed for 10 minutes under these conditions to ensure complete dispersion of the silica. After completion, the mixture is discharged to obtain the first-stage compound. This compound is pressed into sheets on an open mill and thoroughly cooled to room temperature. A second-stage internal mixing is then performed: the cooled first-stage compound is returned to the internal mixer, and 4-vinylpyridine is added first at 60 rpm and a temperature of 80°C, and mixed for 2 minutes to ensure uniform dispersion. Next, sulfur and accelerator CZ are added, and mixing continues for 3 minutes. After completion, the mixture is discharged to obtain the final two-stage compound. Finally, the two-stage compound was placed on a flat vulcanizing machine at 160℃ and 15MPa and vulcanized in a mold for 20 minutes to obtain a vulcanized rubber sheet with a thickness of 2 mm, which was used for subsequent performance testing.

[0043] Comparative Example 4 The formula, by weight, is as follows: 80 parts functionalized polybutadiene rubber, 20 parts terminal mercapto liquid polyisoprene with a number average molecular weight of 1500, 42 parts fumed silica, 1.2 parts 4-vinylpyridine, 2.0 parts sulfur, and 1.3 parts accelerator CZ (N-cyclohexyl-2-benzothiazole sulfenamide).

[0044] The preparation process strictly follows a two-stage mixing process. First, a single-stage internal mixing is performed: functionalized polybutadiene rubber and mercapto-terminated liquid polyisoprene are added to a Hacker internal mixer and plasticized for 2 minutes at 60 rpm and an initial temperature of 100°C to soften the rubber. Then, silica is added in batches while the temperature of the mixing chamber is raised to 155°C, and the mixture is vigorously mixed for 10 minutes under these conditions to ensure complete dispersion of the silica. After completion, the mixture is discharged to obtain the first-stage compound. This compound is pressed into sheets on an open mill and thoroughly cooled to room temperature. A second-stage internal mixing is then performed: the cooled first-stage compound is returned to the internal mixer, and 4-vinylpyridine is added first at 60 rpm and a temperature of 80°C, and mixed for 2 minutes to ensure uniform dispersion. Next, sulfur and accelerator CZ are added, and mixing continues for 3 minutes. After completion, the mixture is discharged to obtain the final two-stage compound. Finally, the two-stage compound was placed on a flat vulcanizing machine at 160℃ and 15MPa and vulcanized in a mold for 20 minutes to obtain a vulcanized rubber sheet with a thickness of 2 mm, which was used for subsequent performance testing.

[0045] Comparative Example 5 The formula, by weight, is as follows: 80 parts of cis-butadiene rubber, 20 parts of terminal thiol liquid polyisoprene with a number average molecular weight of 1500, 13 parts of hydrogenated rosin ester, 42 parts of silica, 1.2 parts of 4-vinylpyridine, 2.0 parts of sulfur, and 1.3 parts of accelerator CZ (N-cyclohexyl-2-benzothiazole sulfenamide).

[0046] The preparation process strictly follows a two-stage mixing process. First, a single-stage internal mixing is performed: cis-butadiene rubber, mercapto-terminated liquid polyisoprene, and hydrogenated rosin ester are added to a Hacker internal mixer and plasticized for 2 minutes at 60 rpm and an initial temperature of 100°C to soften the rubber. Then, silica is added in batches while the temperature of the mixing chamber is raised to 155°C, and the mixture is vigorously mixed for 10 minutes under these conditions to ensure complete dispersion of the silica. After completion, the mixture is discharged, yielding the first-stage compound. This compound is pressed into sheets on an open mill and thoroughly cooled to room temperature. A second-stage internal mixing is then performed: the cooled first-stage compound is returned to the internal mixer, and 4-vinylpyridine is added first, and mixed for 2 minutes at 60 rpm and 80°C to ensure uniform dispersion. Next, sulfur and accelerator CZ are added, and mixing continues for 3 minutes. After completion, the mixture is discharged, yielding the final two-stage compound. Finally, the two-stage compound was placed on a flat vulcanizing machine at 160℃ and 15MPa and vulcanized in a mold for 20 minutes to obtain a vulcanized rubber sheet with a thickness of 2 mm, which was used for subsequent performance testing.

[0047] The vulcanized rubber samples prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to a series of performance tests in accordance with relevant national standards. The test results are summarized in Table 1 below.

[0048] Testing standards: Tensile strength and elongation at break GB / T 528-2009; Wetland grip performance was measured using DMA (tanδ@0℃); rolling resistance performance was measured using DMA (tanδ@60℃); test conditions for tanδ@0℃ and tanδ@60℃: DMA temperature scan, frequency 10Hz, strain 0.1%; Dynamic flexural fatigue life: GB / T 1687.4-2021, recording the number of flexural cycles under a grade 6 crack; Ozone aging cracking: GB / T 7762-2014, ozone concentration 50 pphm, 20% strain; Self-healing rate: A standard puncture damage was created on a vulcanized rubber sample, and after 48 hours, the degree of recovery of tensile strength before and after repair was compared.

[0049] Table 1 Performance test results of the rubber compounds prepared in Examples 1-3 and Comparative Examples 1-5 As can be seen from the data in the table above, the technical effects of the embodiments of the present invention are significant. The flexural cycles under level 6 cracks in Examples 1 and 3 both exceeded 450,000, and Example 2 reached 410,000, while the comparative example 1 of the prior art only reached 110,000, and the fatigue lives of the other comparative examples 2 to 5, which lacked key components, were only between 90,000 and 210,000. This indicates that the present invention, by constructing a complete dynamic self-healing network, significantly improves the fatigue resistance of the material.

[0050] Examples 1-3 all exhibited significant self-healing capabilities, while Comparative Examples 1, 3, and 5 showed repair efficiencies of <20%. It is noteworthy that Comparative Example 2 (lacking 4-vinylpyridine) and Comparative Example 4 (lacking ester-containing resin), although still possessing some repair efficiency, were primarily attributed to the "molecular glue" effect of the terminal thiol-containing liquid polyisoprene, and their effectiveness was far less than that of the examples demonstrating the synergistic effect of all three components. This fully demonstrates that the functionalized rubber, 4-vinylpyridine, ester-containing resin, and terminal thiol-containing liquid polyisoprene are all indispensable for achieving efficient self-healing, exhibiting a significant synergistic effect.

[0051] The loss factor (tanδ) at 60℃ characterizes rolling resistance; the lower the value, the more energy-efficient it is. At 0℃, tanδ characterizes wet grip; the higher the value, the safer it is. In Example 1, the tanδ value at 60℃ is much lower than that of Comparative Example 1, indicating a significant reduction in rolling resistance. However, at 0℃, the tanδ value of Example 1 is much higher than that of Comparative Example 1, indicating a substantial improvement in wet grip performance.

[0052] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A sidewall rubber composition, characterized in that, The product comprises the following components by weight: 100 parts of matrix rubber, which is composed of 72-88 parts of functionalized polybutadiene rubber and 12-28 parts of terminal thiol-terminated liquid polyisoprene; 0.5-2.0 parts of 4-vinylpyridine; 10-16 parts of resin containing ester groups; 35-50 parts of reinforcing agent; and 2.3-4.3 parts of vulcanization system; wherein the functionalized polybutadiene rubber is a polybutadiene rubber with sulfur-nitrogen bond functional groups introduced at the end groups.

2. The sidewall rubber composition according to claim 1, characterized in that, The number-average molecular weight of the terminal thiol-terminated liquid polyisoprene is 900-2200.

3. The sidewall rubber composition according to claim 1, characterized in that, The mass ratio of the functionalized polybutadiene rubber to the mercapto-terminated liquid polyisoprene is (4.5-7.0):

1.

4. The sidewall rubber composition according to claim 1, characterized in that, The reinforcing agent is silica, and the resin containing ester groups is selected from at least one of hydrogenated rosin esters and terpene phenolic resins.

5. The sidewall rubber composition according to claim 1, characterized in that, The vulcanization system comprises: 1.5-2.5 parts sulfur and 0.8-1.8 parts accelerator.

6. The sidewall rubber composition according to claim 1, characterized in that, The preparation method of the functionalized polybutadiene rubber is as follows: under nitrogen protection, 1,3-butadiene is dissolved in a non-polar solvent for anionic polymerization reaction, and then a thiourea compound is added to continue the reaction to obtain the functionalized polybutadiene rubber.

7. A method for preparing the sidewall rubber composition according to any one of claims 1-6, characterized in that, The method is as follows: (1) First stage of intensive mixing: Functionalized polybutadiene rubber, mercapto-terminated liquid polyisoprene, ester-containing resin and reinforcing agent are mixed to obtain a first stage of compound; (2) Two-stage mixing: 4-vinylpyridine and vulcanization system are added to the first-stage compound, and the compound is further mixed to obtain the second-stage compound; (3) Vulcanization: The two-stage compound rubber is vulcanized to obtain the sidewall rubber composition.

8. The method for preparing the sidewall rubber composition according to claim 7, characterized in that, In step (1), the temperature of the first stage of intensive mixing is 150-160℃, and the mixing time is 8-12 minutes.

9. The method for preparing the sidewall rubber composition according to claim 7, characterized in that, The 4-vinylpyridine is added in step (2), and the mixture is continued for 1-3 minutes after addition.

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