A modified carbon nanotube rubber composition for tire tread with low heat build-up and high wear resistance

Abstract

The application belongs to the technical field of rubber materials, and particularly relates to a modified carbon tube rubber composition for tire tread with low heat generation and high wear resistance. The rubber composition comprises 100 parts of diene rubber, 40-80 parts of reinforcing filler composed of carbon black and polymer grafted modified white carbon black, 0.5-3 parts of modified carbon nanotube, and plasticizer, vulcanization activator, antioxidant, vulcanizing agent and accelerator. The modified carbon nanotube is prepared by acidification, grafting MPTMS and then grafting end-vinyl polybutadiene, and the polymer grafted modified white carbon black is prepared by grafting KH560 and then grafting end-hydroxyl polybutadiene. The rubber composition of the application can significantly improve wear resistance and fatigue life, while reducing dynamic heat generation and rolling resistance, and realizes the synergistic improvement of low heat generation, high wear resistance and high durability.

Description

Technical Field

[0001] This invention belongs to the field of rubber material technology, specifically relating to a modified carbon fiber rubber composition for tire treads that has low heat generation and high wear resistance. Background Technology

[0002] With increasingly stringent global automotive emission regulations, especially the upcoming implementation of the Euro 7 emission standard, not only are higher requirements placed on vehicle exhaust emissions, but also, for the first time, restrictions are imposed on tire particulate matter emissions. This means that the tire industry must significantly improve the wear resistance and durability of tread rubber while maintaining excellent wet grip performance and low rolling resistance to reduce the generation of fine particulate matter. However, tire tread rubber reinforcement systems have long faced the "magic triangle" dilemma of balancing wear resistance, rolling resistance, and wet grip performance.

[0003] Currently, the most commonly used reinforcing fillers in tire tread rubber are carbon black and silica. Carbon black exhibits high friction between fillers and between carbon black and the rubber matrix, resulting in significant hysteresis heat generation under dynamic conditions and consequently higher tire rolling resistance. Furthermore, carbon black-reinforced rubber has a low coefficient of friction with wet surfaces, limiting its anti-skid performance. Silica reduces friction and hysteresis heat generation between fillers, effectively lowering rolling resistance. However, silica itself is highly polar, resulting in weaker interfacial interaction with rubber and a less effective reinforcing effect compared to carbon black. Additionally, silica has poor electrical and thermal conductivity, making it difficult to meet the antistatic and heat dissipation requirements of tires during high-speed driving, which is detrimental to durability.

[0004] Carbon nanotubes, as a one-dimensional nanomaterial, possess extremely high modulus, aspect ratio, and specific surface area. Theoretically, they can form numerous physical connection points in a rubber matrix and synergistically construct a more complete stress transfer network with fillers such as carbon black, thereby significantly improving the mechanical properties, wear resistance, and fatigue resistance of rubber. Simultaneously, the excellent electrical and thermal conductivity of carbon nanotubes also promises to improve the antistatic properties and heat dissipation capabilities of tires. However, the application of carbon nanotubes in rubber has long faced two major bottlenecks. First, due to van der Waals forces, carbon nanotubes easily entangle with each other, forming dense aggregates that are difficult to disperse uniformly under conventional rubber compounding conditions. These aggregates become stress concentration points in the rubber, which can actually reduce mechanical properties and wear resistance. Second, the surface chemical inertness of carbon nanotubes is relatively high, resulting in weak interfacial interactions with rubber molecules. During dynamic strain, slippage easily occurs, leading to a significant increase in hysteresis heat generation, especially a sharp rise in compression heat generation under large strain conditions. Rubber materials have thermo-coupling properties. Increased temperature leads to a decrease in modulus and hardness, an increase in the contact area with the ground, and accelerated thermo-oxidative aging, ultimately resulting in a significant reduction in wear resistance and fatigue life.

[0005] Therefore, how to effectively suppress the aggregation tendency and reduce dynamic heat generation of carbon nanotubes while making full use of their advantages of high modulus and high aspect ratio has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a modified carbon nanotube rubber composition for tire treads that has low heat generation and high wear resistance, in order to overcome the technical defects of existing carbon nanotubes that are prone to agglomeration in the rubber matrix and have weak interfacial bonding with the rubber, resulting in high dynamic heat generation. This invention enables the modified carbon nanotubes to be uniformly dispersed in the rubber and form a strong interfacial bond, thereby significantly improving the wear resistance and fatigue durability of the tread rubber while effectively reducing dynamic heat generation and rolling resistance.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A modified carbon nanotube rubber composition for tire treads with low heat generation and high wear resistance, comprising the following components by weight: 100 parts diene rubber; 40-80 parts reinforcing filler, wherein the reinforcing filler is composed of carbon black and polymer-grafted modified silica; 0.5-3 parts modified carbon nanotubes; 1-10 parts plasticizer; 2-8 parts vulcanization activator; 1-5 parts antioxidant; 0.5-3 parts vulcanizing agent; and 0.5-2.5 parts accelerator. The modified carbon nanotubes are prepared by the following method: (1) Acid treatment of carbon nanotubes; (2) Disperse the product obtained in step (1) in anhydrous ethanol, add 3-mercaptopropyltrimethoxysilane (MPTMS), react, and then filter, wash and dry; (3) Disperse the product obtained in step (2) in tetrahydrofuran, add terminal vinyl polybutadiene and photoinitiator, react, then filter, wash and dry to obtain modified carbon nanotubes.

[0008] Further, the acid treatment in step (1) specifically involves adding carbon nanotubes to a mixture of concentrated sulfuric acid and concentrated nitric acid, stirring and refluxing at 60-80°C for 2-6 hours, and then filtering, washing, and drying.

[0009] Furthermore, the reaction temperature in step (2) is 60-80℃, and the reaction time is 4-12 hours; the amount of 3-mercaptopropyltrimethoxysilane used is 15%-35% of the mass of carbon nanotubes.

[0010] Further, the reaction in step (3) is carried out under ultraviolet light irradiation for 2-8 hours; the number average molecular weight of the terminal vinyl polybutadiene is 1000-3000, and the amount used is 40%-80% of the mass of carbon nanotubes.

[0011] Furthermore, the photoinitiator is a free radical photoinitiator, such as 2-hydroxy-2-methyl-1-phenylpropanone (1173), 1-hydroxycyclohexylphenyl methyl ketone (184), or 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone (2959).

[0012] The modified carbon nanotubes of this invention employ a stepwise strategy of first grafting MPTMS and then grafting terminal vinyl polybutadiene. The two grafts form a composite structure on the carbon nanotube surface with clearly defined functions and synergistic effects. MPTMS has a short molecular chain, and its terminal thiol groups can react efficiently with the rubber molecular chain during rubber vulcanization, firmly anchoring the carbon nanotube to the rubber crosslinking network with high-density covalent bonds. Terminal vinyl polybutadiene has a long molecular chain, and its vinyl groups also participate in vulcanization, establishing a flexible long-chain buffer interface between the carbon nanotube and the rubber. If only MPTMS is grafted, although chemical anchoring is sufficient, its short chain length cannot effectively buffer stress concentration under dynamic strain, and the contact between the carbon nanotube and the rubber remains approximately rigid, making it difficult to reduce interfacial friction. If only terminal vinyl polybutadiene is grafted, although the flexible chain is long enough and the steric hindrance effect is significant, its grafting density and end-group reactivity are not as good as MPTMS, resulting in insufficient chemical anchoring and the inability to eliminate dynamic slippage. By combining the two, short-chain MPTMS provides high-density, highly active chemical anchoring, while long-chain polybutadiene provides flexible buffering and steric hindrance, together forming a synergistic interface structure of short-chain anchoring and long-chain buffering, thereby improving wear resistance and fatigue performance while reducing dynamic heat generation and rolling resistance.

[0013] Furthermore, the polymer-grafted modified silica is prepared by the following method: (a) Silica is dispersed in an organic solvent, and γ-glycidoxypropyltrimethoxysilane (KH560) is added and reacted to obtain epoxy-oxidized silica; (b) Epoxylated silica is dispersed in an organic solvent, hydroxyl-terminated polybutadiene (HTPB) and triphenylphosphine are added, and the mixture is reacted under a nitrogen atmosphere. The mixture is then filtered, washed and dried to obtain the polymer-grafted modified silica.

[0014] Further, in step (a), the amount of γ-glycidyl etheroxypropyltrimethoxysilane used is 5%-20% of the mass of silica; the reaction temperature is 100-120℃, and the reaction time is 6-10 hours.

[0015] Furthermore, the number-average molecular weight of the hydroxyl-terminated polybutadiene is 1000-3000; the reaction temperature in step (b) is 80-120℃, and the reaction time is 8-16 hours.

[0016] The hydroxyl-terminated polybutadiene segments grafted onto the surface of polymer-grafted modified silica have a structure similar to the rubber matrix. During vulcanization, these flexible chains participate in the cross-linking reaction, forming a covalently linked flexible interface layer around the silica. Compared to the rigid monolayer formed by traditional small-molecule silane-modified silica, the flexible polymer segments effectively buffer stress concentration under dynamic strain, avoiding rigid friction and slippage at the filler-rubber interface, thereby reducing hysteretic heat generation. Simultaneously, the steric hindrance effect of this polymer layer is significantly better than that of small molecules, effectively preventing hydrogen bond aggregation between silica particles and resulting in more uniform dispersion within the rubber.

[0017] In this formulation, the terminal vinyl polybutadiene on the surface of modified carbon nanotubes and the terminal hydroxyl polybutadiene on the surface of modified silica can co-crosslink with the double bonds of the rubber matrix, connecting the carbon nanotubes and silica in a flexible crosslinked network rather than in isolation. This unified flexible interface network ensures chemical bonding between the filler and the rubber while avoiding stress concentration and heat generation caused by direct contact with rigid fillers. Carbon black acts as a physical reinforcing point, further enhancing the modulus and wear resistance of the network. When used in combination, under stress, the stress is first uniformly distributed to each filler through the flexible interface layer. The carbon nanotubes bear the long-range tensile force, while the silica and carbon black bear the local compression and filling force. Interfacial slip is suppressed by covalent crosslinking, thus significantly improving wear resistance and fatigue performance while reducing dynamic heat generation.

[0018] Further, the diene rubber comprises 20-100 parts of natural rubber, 0-40 parts of butadiene rubber, and 0-60 parts of styrene-butadiene rubber, totaling 100 parts.

[0019] Furthermore, the weight ratio of the carbon black to the polymer-grafted modified silica is 1:2-2:1.

[0020] Further, the carbon black is one or more of N134, N234, or N330; the vulcanizing agent is sulfur; the accelerator is N-tert-butyl-2-benzothiazole sulfenamide (NS); the vulcanization activator is zinc oxide and stearic acid; the antioxidant is a mixture of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (antioxidant 4020) and 2,2,4-trimethyl-1,2-dihydroquinoline polymer (antioxidant RD); and the plasticizer is environmentally friendly aromatic oil (TDAE).

[0021] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. The modified carbon nanotubes were simultaneously grafted with MPTMS and terminal vinyl polybutadiene. The thiol groups of MPTMS participated in vulcanization to covalently anchor the carbon nanotubes to the rubber network, while the long chains of terminal vinyl polybutadiene provided flexible buffering and steric hindrance. The two worked together to solve the bottlenecks of easy agglomeration and high dynamic heat generation of carbon nanotubes.

[0022] 2. The hydroxyl-terminated polybutadiene grafted onto the surface of silica forms a flexible interface layer, which is different from the rigid monolayer modified by traditional small molecule silanes, further reducing the hysteretic heat generation at the filler-rubber interface.

[0023] 3. Carbon black, polymer-grafted modified silica, and modified carbon nanotubes are combined. The carbon nanotubes construct a long-range framework network, while the carbon black and silica fill the gaps. Furthermore, the polymer graft chains of the two modified fillers participate in cross-linking during the vulcanization process, forming a unified flexible interface network.

[0024] 4. Based on the above formulation design, the modified carbon fiber rubber composition of the present invention significantly improves wear resistance and fatigue durability, while reducing dynamic heat generation and rolling resistance, achieving a breakthrough in comprehensive performance of low heat generation, high wear resistance, and high durability. Attached Figure Description

[0025] Figure 1 SEM images of unmodified carbon nanotubes and modified carbon nanotubes prepared in Example 1.

[0026] Figure 2 The image shows the AFM diagram of the modified carbon nanotube rubber composition prepared in Example 1. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the raw materials used in the embodiments are all commercially available products.

[0028] Example 1 This embodiment provides a modified carbon nanotube rubber composition for tire treads with low heat generation and high wear resistance, comprising the following components by weight: 70 parts natural rubber, 30 parts butadiene rubber, 30 parts N234 carbon black, 30 parts polymer-grafted modified silica, 1.0 part modified carbon nanotubes, 5 parts environmentally friendly aromatic oil (TDAE), 3 parts zinc oxide, 2 parts stearic acid, 2.0 parts N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (antioxidant 4020), 1.5 parts 2,2,4-trimethyl-1,2-dihydroquinoline polymer (antioxidant RD), 1.5 parts sulfur, and 1.2 parts N-tert-butyl-2-benzothiazole sulfenamide (NS).

[0029] The modified carbon nanotubes are prepared by the following method: (1) Add 10g of arrayed multi-walled carbon nanotubes to 200mL of a mixture of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1, stir and reflux at 70℃ for 4 hours, then filter, wash with deionized water until the filtrate is neutral, and vacuum dry at 80℃ for 12 hours to obtain acidified carbon nanotubes.

[0030] (2) Disperse the acidified carbon nanotubes obtained in step (1) in 200 mL of anhydrous ethanol, add 2.5 g of 3-mercaptopropyltrimethoxysilane (MPTMS), stir the reaction at 70 °C for 8 hours, then filter, wash 3 times with anhydrous ethanol, and vacuum dry at 60 °C for 10 hours to obtain MPTMS grafted carbon nanotubes.

[0031] (3) Disperse the MPTMS grafted carbon nanotubes obtained in step (2) in 200 mL of tetrahydrofuran, add 6.0 g of end vinyl polybutadiene (number average molecular weight 2000) and 0.06 g of photoinitiator 1173, stir and react for 5 hours under ultraviolet light irradiation, then filter, wash 3 times with tetrahydrofuran, and vacuum dry at 60 °C for 10 hours to obtain modified carbon nanotubes.

[0032] The polymer-grafted modified silica is prepared by the following method: (a) 50 g of silica was dispersed in 500 mL of toluene, 5.0 g of KH560 was added, and the mixture was stirred at 110 °C for 8 hours. After cooling, the mixture was filtered, washed three times with toluene, and dried under vacuum at 80 °C for 12 hours to obtain epoxy-oxidized silica.

[0033] (b) The epoxy-modified silica obtained in step (a) was dispersed in 500 mL of toluene, 10 g of hydroxyl-terminated polybutadiene (number average molecular weight 2000) and 0.1 g of triphenylphosphine were added, and the mixture was stirred at 100 °C for 12 hours under a nitrogen atmosphere. After cooling, the mixture was filtered, washed three times with toluene, and dried under vacuum at 80 °C for 12 hours to obtain polymer-grafted modified silica.

[0034] The preparation method of the above-mentioned modified carbon nanotube rubber composition is as follows: Preheat the internal mixer to 85°C, add natural rubber and butadiene rubber, and masticate for 40 seconds at a rotor speed of 80 rpm. Then add N234 carbon black, polymer-grafted modified silica, modified carbon nanotubes, environmentally friendly aromatic oil, zinc oxide, stearic acid, antioxidant 4020, and antioxidant RD. Reduce the rotor speed to 70 rpm and mix until the temperature reaches 125°C. Remove the impeller and continue mixing until 160°C to discharge the rubber, obtaining the masterbatch. After cooling the masterbatch to room temperature, add sulfur and accelerator NS at 60°C on a two-roll mill, mix evenly, and control the rubber compound temperature to not exceed 110°C. Sheet the final compound to obtain the final compound. Vulcanize the final compound at 150°C and 15 MPa for 20 minutes to obtain the low-heat-generating, high-wear-resistant modified carbon nanotube rubber composition for tire treads.

[0035] SEM (scanning electron microscope) images of unmodified carbon nanotubes and modified carbon nanotubes prepared in Example 1 are shown below. Figure 1 As shown. AFM (atomic force microscopy) of the modified carbon nanotube rubber composition prepared in Example 1 is shown below. Figure 2 As shown. By Figure 1 SEM characterization showed that the unmodified carbon nanotubes (A) exhibited significant agglomeration and severe entanglement; after modification by the method of the present invention (B), the carbon nanotubes showed significantly improved dispersibility, greatly reduced entanglement, and good individual dispersion. Figure 2 AFM characterization further confirmed that the modified carbon nanotubes can be uniformly dispersed in the rubber matrix, the composite material has a uniform surface morphology, uniform elastic modulus distribution, and excellent interfacial bonding state, providing microstructure guarantee for the material's low heat generation and high wear resistance.

[0036] Example 2 This embodiment provides a modified carbon nanotube rubber composition for tire treads with low heat generation and high wear resistance, comprising the following components by weight: 50 parts natural rubber, 20 parts butadiene rubber, 30 parts styrene-butadiene rubber, 20 parts N134 carbon black, 40 parts polymer-grafted modified silica, 2.5 parts modified carbon nanotubes, 3 parts environmentally friendly aromatic oil (TDAE), 5 parts zinc oxide, 1.5 parts stearic acid, 1.5 parts N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (antioxidant 4020), 1.0 part 2,2,4-trimethyl-1,2-dihydroquinoline polymer (antioxidant RD), 2.0 parts sulfur, and 1.8 parts N-tert-butyl-2-benzothiazole sulfenamide (NS).

[0037] The modified carbon nanotubes are prepared by the following method: (1) Add 10g of arrayed multi-walled carbon nanotubes to 200mL of a mixture of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1, stir and reflux at 65℃ for 5 hours, then filter, wash with deionized water until the filtrate is neutral, and vacuum dry at 80℃ for 12 hours to obtain acidified carbon nanotubes.

[0038] (2) Disperse the acidified carbon nanotubes obtained in step (1) in 200 mL of anhydrous ethanol, add 1.8 g of 3-mercaptopropyltrimethoxysilane (MPTMS), stir the reaction at 65 °C for 10 hours, then filter, wash three times with anhydrous ethanol, and vacuum dry at 60 °C for 10 hours to obtain MPTMS grafted carbon nanotubes.

[0039] (3) Disperse the MPTMS grafted carbon nanotubes obtained in step (2) in 200 mL of tetrahydrofuran, add 7.0 g of end vinyl polybutadiene (number average molecular weight 1500) and 0.07 g of photoinitiator 184, stir and react for 6 hours under ultraviolet light irradiation, then filter, wash 3 times with tetrahydrofuran, and vacuum dry at 60 °C for 10 hours to obtain modified carbon nanotubes.

[0040] The polymer-grafted modified silica is prepared by the following method: (a) 50g of silica was dispersed in 500mL of toluene, 7.5g of KH560 was added, and the mixture was stirred at 105℃ for 9 hours. After cooling, the mixture was filtered, washed three times with toluene, and dried under vacuum at 80℃ for 12 hours to obtain epoxy-oxidized silica.

[0041] (b) The epoxy-modified silica obtained in step (a) was dispersed in 500 mL of toluene, 12 g of hydroxyl-terminated polybutadiene (number average molecular weight 2500) and 0.12 g of triphenylphosphine were added, and the mixture was stirred at 90 °C for 14 hours under a nitrogen atmosphere. After cooling, the mixture was filtered, washed three times with toluene, and dried under vacuum at 80 °C for 12 hours to obtain polymer-grafted modified silica.

[0042] The preparation method of the above-mentioned modified carbon nanotube rubber composition is as follows: Preheat the internal mixer to 85°C, add natural rubber, butadiene rubber, and styrene-butadiene rubber, and masticate for 40 seconds at a rotor speed of 80 rpm. Then add N134 carbon black, polymer-grafted modified silica, modified carbon nanotubes, environmentally friendly aromatic oil, zinc oxide, stearic acid, antioxidant 4020, and antioxidant RD. Reduce the rotor speed to 70 rpm and mix until the temperature reaches 125°C. Remove the impeller and continue mixing until 160°C to discharge the rubber, obtaining the masterbatch. After cooling the masterbatch to room temperature, add sulfur and accelerator NS at 60°C on a two-roll mill, mix evenly, and control the rubber compound temperature to not exceed 110°C. Sheet the final compound to obtain the final compound. Vulcanize the final compound at 150°C and 15 MPa for 20 minutes to obtain the modified carbon nanotube rubber composition for tire treads with low heat generation and high wear resistance.

[0043] Comparative Example 1 The difference between this comparative example and Example 1 is that the modified carbon nanotubes were prepared using the following method: (1) Place 10g of arrayed multi-walled carbon nanotubes in a tube furnace and heat-treat at 400°C for 30 minutes in an air atmosphere, then purge with nitrogen to cool to room temperature.

[0044] (2) Add the heat-treated carbon nanotubes to 200 mL of 10% dilute hydrochloric acid, stir at room temperature for 30 minutes, filter, and wash with deionized water 3 times.

[0045] (3) The obtained filter cake was added to 200 mL of 3% polyvinylpyrrolidone (PVP) aqueous solution, stirred for 30 minutes, and ultrasonically dispersed for 10 minutes to obtain a carbon nanotube dispersion. 2 g of bis-(3-triethoxysilanepropyl)-tetrasulfide (Si69) was dispersed in 20 mL of ethanol and added dropwise to the above carbon nanotube dispersion. After the addition was complete, the temperature was raised to 80 °C and reacted for 3 hours. The mixture was filtered, washed three times with anhydrous ethanol, and vacuum dried at 60 °C for 10 hours to obtain modified carbon nanotubes.

[0046] Comparative Example 2 The difference between this comparative example and Example 1 is that the modified carbon nanotubes were prepared using the following method: (1) Add 10g of arrayed multi-walled carbon nanotubes to 200mL of a mixture of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1, stir and reflux at 70℃ for 4 hours, then filter, wash with deionized water until the filtrate is neutral, and vacuum dry at 80℃ for 12 hours to obtain acidified carbon nanotubes.

[0047] (2) Disperse the acidified carbon nanotubes in 200 mL of deionized water, add 5 g of cetyltrimethylammonium bromide (CTAB), stir the reaction at 60 °C for 4 hours, then filter, wash with deionized water 3 times, and vacuum dry at 60 °C for 10 hours to obtain modified carbon nanotubes.

[0048] Comparative Example 3 The difference between this comparative example and Example 1 is that the polymer-grafted modified silica is replaced with Si69 modified silica, and its preparation method is as follows: 50g of silica was dispersed in 500mL of ethanol / water mixed solvent (volume ratio 1:1), and 5g of bis-(3-triethoxysilanepropyl)-tetrasulfide (Si69) was added. The pH was adjusted to 4.5 with glacial acetic acid, and the mixture was stirred at 70℃ for 6 hours. After cooling, the mixture was filtered, washed three times with anhydrous ethanol, and dried under vacuum at 80℃ for 12 hours to obtain Si69 modified silica.

[0049] Comparative Example 4 The difference between this comparative example and Example 1 is that the polymer-grafted modified silica is replaced with KH570 modified silica, and its preparation method is as follows: 50g of silica was dispersed in 500mL of ethanol / water mixed solvent (volume ratio 1:1), and 5g of γ-methacryloxypropyltrimethoxysilane (KH570) was added. The pH was adjusted to 4.5 with glacial acetic acid, and the mixture was stirred at 70℃ for 6 hours. After cooling, the mixture was filtered, washed three times with anhydrous ethanol, and dried under vacuum at 80℃ for 12 hours to obtain KH570 modified silica.

[0050] Comparative Example 5 The difference between this comparative example and Example 1 is that the carbon nanotube rubber composition, by weight, includes the following components: 70 parts natural rubber, 30 parts butadiene rubber, 10 parts N234 carbon black, 20 parts polymer-grafted modified silica, 10 parts modified carbon nanotubes, 5 parts environmentally friendly aromatic oil (TDAE), 3 parts zinc oxide, 2 parts stearic acid, 2.0 parts N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (antioxidant 4020), 1.5 parts 2,2,4-trimethyl-1,2-dihydroquinoline polymer (antioxidant RD), 1.5 parts sulfur, and 1.2 parts N-tert-butyl-2-benzothiazole sulfenamide (NS).

[0051] Performance testing Tensile properties were tested according to GB / T 528-2009; tear strength according to GB / T 529-2008; hardness according to GB / T 531.1-2008; and high-temperature resilience according to GB / T 1681-2009. DIN abrasion resistance was tested according to GB / T 9867-2008. Compression heat generation was tested according to GB / T 1687.3-2016. Dynamic mechanical properties were tested on a DMA instrument under the following conditions: frequency 10Hz, strain 5%, and heating rate 2℃ / min. Flexural fatigue was tested according to GB / T 13934-2006; and tensile fatigue was tested according to GB / T 1688-2008.

[0052] The test results are shown in Table 1.

[0053] Table 1 Performance Test Results

[0054] The performance test results above show that the rubber compositions of Examples 1 and 2 have excellent comprehensive performance, achieving a synergistic improvement in low heat generation, high wear resistance, and high durability.

[0055] Comparative Example 1 uses an oxidation + Si69 grafting method to modify carbon nanotubes. Although this method can introduce some organic groups onto the surface of the carbon nanotubes, the grafted alkyl chain ends lack active functional groups that participate in vulcanization. The interaction between the carbon nanotubes and rubber is mainly physical, resulting in significant interfacial slip under dynamic strain. This leads to higher compression heat and tanδ values ​​than in Example 1, and a significant decrease in wear resistance and fatigue performance. Comparative Example 2 uses CTAB physical adsorption to modify carbon nanotubes. CTAB is non-covalently attached to the surface of the carbon nanotubes through electrostatic and hydrophobic interactions. It is easily desorbed during mixing and vulcanization, resulting in severe carbon nanotube agglomeration and the formation of numerous stress concentration points, significantly reducing all properties. Comparative Example 3 uses small-molecule Si69 to modify silica. Si69 can react with rubber during vulcanization, but its grafted layer is a monolayer with high rigidity. It cannot form a flexible buffer interface between the filler and rubber like polymer-grafted silica, resulting in higher compression heat and tanδ values ​​than in Example 1. Comparative Example 4 used small-molecule KH570 modified silica. KH570 mainly acts as a coupling agent in rubber, and it also lacks the stress buffering effect of flexible segments, resulting in overall performance degradation. Comparative Example 5 reduced the amount of carbon black to 10 parts, the amount of modified silica to 20 parts, and the amount of modified carbon nanotubes to 10 parts. The total amount of reinforcing filler was insufficient and the carbon nanotubes agglomerated excessively, resulting in more defects in the crosslinking network. All properties were far inferior to those of Example 1.

[0056] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A modified carbon fiber rubber composition for tire treads with low heat generation and high wear resistance, characterized in that, By weight, it comprises the following components: 100 parts diene rubber; 40-80 parts reinforcing filler, wherein the reinforcing filler is composed of carbon black and polymer-grafted modified silica; Modified carbon nanotubes 0.5-3 parts; plasticizer 1-10 parts; vulcanization activator 2-8 parts; antioxidant 1-5 parts; vulcanizing agent 0.5-3 parts; accelerator 0.5-2.5 parts; The modified carbon nanotubes are prepared by the following method: (1) Acid treatment of carbon nanotubes; (2) Disperse the product obtained in step (1) in anhydrous ethanol, add 3-mercaptopropyltrimethoxysilane, react, and then filter, wash and dry; (3) Disperse the product obtained in step (2) in tetrahydrofuran, add terminal vinyl polybutadiene and photoinitiator, react, then filter, wash and dry to obtain modified carbon nanotubes.

2. The modified carbon fiber rubber composition for tire tread with low heat generation and high wear resistance according to claim 1, characterized in that, The acid treatment in step (1) specifically involves adding carbon nanotubes to a mixture of concentrated sulfuric acid and concentrated nitric acid, stirring and refluxing at 60-80°C for 2-6 hours, and then filtering, washing, and drying.

3. The modified carbon fiber rubber composition for tire tread with low heat generation and high wear resistance according to claim 1, characterized in that, The reaction temperature in step (2) is 60-80℃, and the reaction time is 4-12 hours; the amount of 3-mercaptopropyltrimethoxysilane used is 15%-35% of the mass of carbon nanotubes.

4. The modified carbon fiber rubber composition for tire tread with low heat generation and high wear resistance according to claim 1, characterized in that, The reaction in step (3) is carried out under ultraviolet light irradiation for 2-8 hours; the number average molecular weight of the terminal vinyl polybutadiene is 1000-3000, and the amount used is 40%-80% of the mass of carbon nanotubes.

5. The modified carbon fiber rubber composition for tire tread with low heat generation and high wear resistance according to claim 1, characterized in that, The polymer-grafted modified silica is prepared by the following method: (a) Silica is dispersed in an organic solvent, γ-glycidoxypropyltrimethoxysilane is added, and the reaction is carried out to obtain epoxy-modified silica; (b) Epoxylated silica is dispersed in an organic solvent, hydroxyl-terminated polybutadiene and triphenylphosphine are added, and the mixture is reacted under a nitrogen atmosphere. Then the mixture is filtered, washed and dried to obtain the polymer-grafted modified silica.

6. The modified carbon fiber rubber composition for tire tread with low heat generation and high wear resistance according to claim 5, characterized in that, The amount of γ-glycidyl etheroxypropyltrimethoxysilane used in step (a) is 5%-20% of the mass of silica; the reaction temperature is 100-120℃ and the reaction time is 6-10 hours.

7. The modified carbon fiber rubber composition for tire tread with low heat generation and high wear resistance according to claim 5, characterized in that, The number average molecular weight of the hydroxyl-terminated polybutadiene is 1000-3000; the reaction temperature in step (b) is 80-120℃ and the reaction time is 8-16 hours.

8. The modified carbon fiber rubber composition for tire tread with low heat generation and high wear resistance according to claim 1, characterized in that, The diene rubber comprises 20-100 parts of natural rubber, 0-40 parts of butadiene rubber, and 0-60 parts of styrene-butadiene rubber, totaling 100 parts.

9. The modified carbon fiber rubber composition for tire tread with low heat generation and high wear resistance according to claim 1, characterized in that, The weight ratio of carbon black to polymer-grafted modified silica is 1:2-2:

1.

10. The modified carbon fiber rubber composition for tire tread with low heat generation and high wear resistance according to claim 1, characterized in that, The carbon black is one or more of N134, N234, or N330; the vulcanizing agent is sulfur; the accelerator is N-tert-butyl-2-benzothiazole sulfenamide; the vulcanization activator is zinc oxide and stearic acid; the antioxidant is a mixture of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline polymer; and the plasticizer is environmentally friendly aromatic oil.

Images