High wet / dry grip tire tread rubber and method of making same

Abstract

This invention belongs to the field of rubber material technology, specifically relating to a high-dry and wet grip tire tread compound and its preparation method. The tread compound comprises, by weight, 100 parts diene rubber, 5-15 parts modified diatomaceous earth, 40-70 parts silica, 0.5-3 parts multi-walled carbon nanotubes, 2-8 parts functionalized resin, 3-8 parts silane coupling agent, and conventional additives. The modified diatomaceous earth is prepared through a three-step process: acid washing and activation, high-temperature dynamic pre-modification in a Banbury mixer, and secondary coating with a titanate coupling agent. When modified diatomaceous earth, multi-walled carbon nanotubes, and functionalized resin coexist in a specific ratio, they form a synergistic effect, constructing micro-drainage channels, a three-dimensional thermally conductive network, and an adhesive reinforcement layer within the rubber compound. The resulting tread compound exhibits significantly improved dry grip, wet grip, and abrasion resistance, without deteriorating rolling resistance. The preparation process is simple and efficient, requires no solvents, and is suitable for the large-scale production of high-performance tire tread compounds.

Description

Technical Field

[0001] This invention belongs to the field of rubber material technology, specifically relating to a tire tread compound with high dry and wet grip and its preparation method. Background Technology

[0002] As the only component of a vehicle that directly contacts the road surface, the tire tread compound's grip performance directly affects driving safety. The balance of grip under different road conditions, particularly dry and wet, has long been a challenge for the tire industry. Traditional tread compound reinforcement systems primarily use carbon black or silica. While carbon black offers excellent dry grip and wear resistance, its wet grip performance is poor, and its reliance on petrochemical resources increases environmental pressure.

[0003] Silica, rich in silanol groups on its surface, can form strong filler-rubber interactions with the rubber matrix. Its aggregated structure also helps to break through surface water films, significantly improving wet grip. Therefore, it is widely used in high-performance tire tread compounds. However, silica's large specific surface area and strong surface polarity make it prone to agglomeration in non-polar rubber matrices, resulting in poor dispersibility. To improve silica dispersion, multi-stage mixing processes and the addition of large amounts of silane coupling agents for in-situ surface modification are typically required. This not only increases mixing energy consumption and process complexity but also prolongs the mixing cycle and raises production costs. Furthermore, even after modification, the dry grip of silica-filled rubber compounds often falls short of the level of carbon black-filled systems, making the synergistic improvement of dry and wet grip a technical bottleneck.

[0004] In recent years, researchers have begun to focus on the application potential of natural porous mineral materials in rubber. Among them, diatomaceous earth, due to its unique disc-shaped or porous microstructure, high specific surface area, good adsorption performance, and low cost, has been explored as a partial replacement for silica or carbon black. The main component of diatomaceous earth is amorphous silica, which retains a large number of naturally formed micron- and nano-sized pores. Theoretically, this structure can form micro-drainage channels on wet and slippery surfaces, thereby enhancing the ability of the rubber compound to break up the water film between the rubber and the wet surface, which is beneficial for improving wet grip. At the same time, the porous structure of diatomaceous earth can also adsorb rubber molecular chains, forming physical entanglement points, which may have a positive impact on the modulus and wear resistance of the rubber compound. However, the surface of diatomaceous earth is also rich in silanol groups, exhibiting strong hydrophilicity, while commonly used tire rubbers such as solution-polymerized styrene-butadiene rubber and cis-butadiene rubber are hydrophobic polymers, resulting in extremely poor thermodynamic compatibility between the two. Directly filling rubber with untreated diatomaceous earth will cause the filler to agglomerate severely in the matrix, forming a large number of stress concentration points, which will reduce the tensile strength, elongation at break and wear resistance of the rubber compound, and even worsen the dynamic fatigue performance.

[0005] To address the compatibility issue between diatomaceous earth and rubber, existing technologies have attempted surface modification of diatomaceous earth. Common modification methods include wet or dry treatment of diatomaceous earth using silane coupling agents, titanate coupling agents, or surfactants. Wet modification typically requires dispersing diatomaceous earth in a water or organic solvent system containing the coupling agent, involving multiple steps such as hydrolysis, stirring, filtration, and drying. This process is cumbersome, time-consuming, and the large-scale use of organic solvents does not meet environmental protection requirements. While dry modification is relatively simpler, it mostly employs simple mechanical mixing methods, making it difficult for the coupling agent to spread evenly and bond firmly on the diatomaceous earth surface, resulting in unstable modification effects. More importantly, in actual tire tread rubber compounding, if untreated diatomaceous earth is directly added to rubber along with silica and silane coupling agents, the silane coupling agents preferentially react with silica, which has a larger specific surface area and higher surface activity, leading to insufficient surface modification of the diatomaceous earth and failing to achieve good dispersion.

[0006] Therefore, how to develop a simple, efficient modification method that can fully utilize the structural characteristics of diatomaceous earth and combine it with silica to form a synergistic reinforcing system, thereby preparing a tire tread compound with both excellent dry and wet grip, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a tire tread compound with high dry and wet grip and its preparation method, aiming to solve the problems in the prior art where poor compatibility between diatomaceous earth and rubber matrix leads to a decline in the mechanical properties of the compound and difficulty in achieving both dry and wet grip. This invention aims to obtain a tire tread compound that simultaneously possesses excellent dry grip, wet grip and good mechanical properties.

[0008] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides a high-dry-wet grip tire tread compound, comprising the following components by weight: 100 parts diene rubber, 5-15 parts modified diatomaceous earth, 40-70 parts silica, 0.5-3 parts multi-walled carbon nanotubes, 2-8 parts functionalized resin, 3-8 parts silane coupling agent, 3-6 parts zinc oxide, 1-3 parts stearic acid, 2-4 parts antioxidant, 1-3 parts accelerator, 1-2.5 parts vulcanizing agent, 5-12 parts processing oil, and 1-3 parts dispersant; The modified diatomaceous earth is prepared by the following method: (1) Place the diatomaceous earth in a hydrochloric acid solution, stir and wash, filter, wash and dry to obtain activated diatomaceous earth; (2) Add activated diatomaceous earth and the first silane coupling agent into a mixer, mix at an initial temperature of 80~100℃ for 2~3 min, then raise the temperature to 130~150℃ and keep it constant for 3~5 min, then discharge to obtain primary modified diatomaceous earth; (3) Mix the modified diatomaceous earth with the titanate coupling agent in a high-speed mixer for 5-10 min to obtain the modified diatomaceous earth.

[0009] Further, in step (2), the mass ratio of activated diatomaceous earth to the first silane coupling agent is 10:1 to 8:1; in step (3), the mass ratio of primary modified diatomaceous earth to titanate coupling agent is 20:1 to 15:1.

[0010] Furthermore, the diatomaceous earth has a silica content of ≥90% and a particle size of 1~20 μm.

[0011] After acid washing and activation, diatomaceous earth exposes more active silanol groups on its surface, providing ample reaction sites for subsequent coupling reactions. Subsequently, under the high-temperature dynamic shear conditions of an internal mixer, the silane coupling agent chemically bonds with these silanol groups, grafting hydrophobic organic segments onto the diatomaceous earth surface, transforming it from hydrophilic to hydrophobic, thus significantly reducing the interfacial tension with diene rubber. The secondary coating with titanate coupling agent further fills the residual polar sites on the surface, forming a denser hydrophobic interfacial layer. The modified diatomaceous earth is less prone to agglomeration during rubber compounding, and can be uniformly dispersed in the rubber matrix at a submicron scale, while its inherent micro- and nano-scale porous structure is fully preserved. These channels can act as micro-drainage channels on wet and slippery surfaces, quickly puncturing and dispersing the water film to allow the tire tread to make direct contact with the road surface. On the other hand, they can adsorb and anchor rubber molecular chains to form physical entanglement points. When under dynamic stress, energy is dissipated through the slippage of molecular chains, thereby simultaneously improving dry grip, wet grip, and wear resistance without sacrificing rolling resistance.

[0012] Furthermore, the silica is a highly dispersible precipitated silica with a specific surface area of ​​120~180 m². 2 / g.

[0013] Furthermore, the functionalized resin is a mixture of terpene phenolic resin and C5 petroleum resin, with a mass ratio of 1:2 to 2:1.

[0014] Further, the first silane coupling agent and the silane coupling agent are each independently selected from at least one of bis-(γ-triethoxysilylpropyl)tetrasulfide (Si69), bis-(γ-triethoxysilylpropyl)disulfide (Si75), γ-mercaptopropyltrimethoxysilane (KH590), or γ-aminopropyltriethoxysilane (KH550); the titanate coupling agent is selected from at least one of isopropyltriisostearoyl titanate (TTS) or isopropyltris(dioctylpyrophosphateoxy)titanate (KR-38S).

[0015] Further, the diene rubber is at least one of solution-polymerized styrene-butadiene rubber, cis-butadiene rubber, and natural rubber; the antioxidant is at least one of p-phenylenediamine antioxidants and quinoline antioxidants; the accelerator is at least one of sulfenamide accelerators and guanidine accelerators; the vulcanizing agent is insoluble sulfur; the processing oil is TDAE environmentally friendly processing oil; and the dispersant is a fatty acid ester dispersant or a polyethylene glycol dispersant.

[0016] Furthermore, the mass ratio of the modified diatomaceous earth, multi-walled carbon nanotubes, and functionalized resin is (8~12):1:(3~6).

[0017] In this invention, when modified diatomaceous earth, multi-walled carbon nanotubes, and functionalized resin coexist in a specific ratio, they can produce a synergistic effect. The porous structure of modified diatomaceous earth provides micron-sized channels, which can quickly pierce the water film to form drainage channels under wet road conditions. At the same time, the pore walls adsorb rubber molecular chains to form physical entanglements, improving the hysteresis loss required for grip on dry surfaces. Multi-walled carbon nanotubes have a high aspect ratio and excellent thermal and electrical conductivity. They can construct a three-dimensional network in the rubber matrix, dissipating energy through interfacial slip on the one hand, and rapidly dissipating heat generated under dynamic loads on the other hand, avoiding excessive local temperature rise that would lead to a decrease in grip. The functionalized resin is a mixture of terpene phenolic resin and C5 petroleum resin. The terpene phenolic resin contains polar groups such as phenolic hydroxyl groups and ester groups, forming a microphase separation structure with the non-polar rubber. This creates an adhesive layer effect on wet pavements, enhancing molecular-level contact. The C5 petroleum resin, as a non-polar tackifier, improves the compatibility between the resin and the rubber matrix and regulates the glass transition temperature of the system. The combination of these two components simultaneously addresses both wet pavement adhesion and dry pavement hysteresis. When these three components work synergistically, modified diatomaceous earth ensures uniform dispersion of the filler and prevents carbon nanotube aggregation. The carbon nanotubes penetrate the pores of the diatomaceous earth and form a connected network with the resin region. The functionalized resin fills interfacial voids and enhances overall cohesive strength, ultimately resulting in a simultaneous improvement in dry pavement grip, wet pavement grip, and abrasion resistance.

[0018] The second aspect of this invention provides a method for preparing the above-mentioned high dry and wet grip tire tread compound, comprising the following steps: (1) First stage of compounding: Add diene rubber to a mixer for plasticizing, then add silica, modified diatomaceous earth, multi-walled carbon nanotubes, functionalized resin, silane coupling agent, zinc oxide, stearic acid, antioxidant, processing oil and dispersant, mix, and discharge to obtain a first stage of compounded rubber. (2) Two-stage mixing: After cooling the first-stage compound to room temperature, it is put back into the internal mixer for mixing and then discharged to obtain the second-stage compound. (3) Final mixing: After cooling the two-stage compound to room temperature, add it to a two-roll mill or internal mixer, then add accelerator and vulcanizing agent, mix, discharge the rubber and sheet to obtain the tire tread rubber.

[0019] Further, the mixing temperature in step (1) is 140~160℃ and the mixing time is 2~5 min; the mixing temperature in step (2) is 100~130℃ and the mixing time is 1~3 min; the mixing temperature in step (3) is 80~110℃ and the mixing time is 1~3 min.

[0020] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. This invention employs a three-step process of acid washing and activation, high-temperature dynamic pre-modification in a mixer, and secondary coating with a titanate coupling agent to transform the surface of diatomaceous earth from hydrophilic to hydrophobic while fully preserving its internal micro-nano-scale porous structure. This solves the problems of easy agglomeration and weak interfacial bonding of diatomaceous earth in rubber matrices. The modification process requires no organic solvents, is time-efficient, and is suitable for industrial applications.

[0021] 2. This invention combines modified diatomaceous earth with multi-walled carbon nanotubes and functionalized resin in a specific ratio, resulting in a synergistic effect: the porous structure of the modified diatomaceous earth forms micro-drainage channels on wet pavements and adsorbs rubber molecular chains; the multi-walled carbon nanotubes construct a heat-conducting network and dissipate the heat generated by dynamic loads; and the terpene phenolic resin in the functionalized resin, when combined with C5 petroleum resin, enhances the adhesion of wet pavements and optimizes the hysteresis loss on dry surfaces.

[0022] 3. The tread compound using the present invention significantly improves wear resistance, dry grip and wet grip while maintaining tensile strength and elongation at break comparable to the benchmark, while rolling resistance and compression heat generation remain basically unchanged. It truly achieves a synergistic improvement in dry and wet grip. At the same time, the process is simple and the cost is controllable, which has outstanding substantive features and significant progress. Detailed Implementation

[0023] 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.

[0024] Example 1 This embodiment provides a high dry and wet grip tire tread compound, which, by weight, comprises the following components: 100 parts solution-polymerized styrene-butadiene rubber, 12 parts modified diatomaceous earth, 55 parts silica, 1 part multi-walled carbon nanotubes, 4 parts functionalized resin, 5 parts silane coupling agent (Si69), 4.5 parts zinc oxide, 2 parts stearic acid, 3 parts antioxidant, 2 parts accelerator, 1.8 parts vulcanizing agent (insoluble sulfur), 8 parts TDAE environmentally friendly operating oil, and 2 parts fatty acid ester dispersant.

[0025] The antioxidant is a mixture of antioxidant 4020 and antioxidant RD in a mass ratio of 2:1; the accelerator is a mixture of accelerator CZ and accelerator DPG in a mass ratio of 4:1; the functionalized resin is a mixture of terpene phenolic resin and C5 petroleum resin in a mass ratio of 1:1; and the silica is highly dispersible precipitated silica with a specific surface area of ​​150 m². 2 / g; the multi-walled carbon nanotubes have an outer diameter of 15 nm and a length of 10 μm.

[0026] The modified diatomaceous earth is prepared by the following method: (1) Place diatomaceous earth (silica content ≥97%, particle size 10 μm) in an 8% hydrochloric acid solution, stir and acid wash at 70℃ for 45 min, filter, wash until neutral, and dry to obtain activated diatomaceous earth; (2) The activated diatomaceous earth and the first silane coupling agent (Si69) were added to the internal mixer at a mass ratio of 9:1. The mixture was stirred at 60 rpm for 2 min at an initial temperature of 90°C. Then the temperature was raised to 140°C and kept constant for 4 min. The mixture was then discharged to obtain the modified diatomaceous earth. (3) Add the modified diatomaceous earth and titanate coupling agent (TTS) at a mass ratio of 18:1 into a high-speed mixer and mix at room temperature for 8 min to obtain modified diatomaceous earth.

[0027] The preparation method of the high dry and wet grip tire tread compound includes the following steps: (1) First stage of mixing: The solution-polymerized styrene-butadiene rubber is added to the internal mixer and plasticized for 30 s. Then, silica, modified diatomaceous earth, multi-walled carbon nanotubes, functionalized resin, silane coupling agent (Si69), zinc oxide, stearic acid, antioxidant, TDAE environmentally friendly processing oil and dispersant are added. The mixture is mixed at 150°C for 3 min and discharged to obtain the first stage of compound. (2) Two-stage mixing: After cooling the first-stage compound to room temperature, put it back into the internal mixer and mix it at 115°C for 2 minutes. Then discharge it to obtain the second-stage compound. (3) Final mixing: After cooling the two-stage compound to room temperature, add it to the open mill, then add the accelerator and vulcanizing agent, mix at 95°C for 2 min, discharge the rubber and sheet it to obtain the tire tread rubber.

[0028] Example 2 This embodiment provides a high dry and wet grip tire tread compound, which, by weight, comprises the following components: 80 parts solution-polymerized styrene-butadiene rubber, 20 parts butadiene rubber, 10 parts modified diatomaceous earth, 60 parts silica, 1.2 parts multi-walled carbon nanotubes, 5 parts functionalized resin, 4.5 parts silane coupling agent (KH590), 5 parts zinc oxide, 2.5 parts stearic acid, 3.5 parts antioxidant, 2.2 parts accelerator, 2 parts vulcanizing agent (insoluble sulfur), 9 parts TDAE environmentally friendly operating oil, and 2.5 parts polyethylene glycol dispersant. The antioxidant is a mixture of antioxidant 4020 and antioxidant RD at a mass ratio of 2:1; the accelerator is a mixture of accelerator CZ and accelerator DPG at a mass ratio of 3:1; the functionalized resin is a mixture of terpene phenolic resin and C5 petroleum resin at a mass ratio of 1.5:1; and the silica is highly dispersible precipitated silica with a specific surface area of ​​160 m². 2 / g; the multi-walled carbon nanotubes have an outer diameter of 12 nm and a length of 8 μm.

[0029] The modified diatomaceous earth is prepared by the following method: (1) Place diatomaceous earth (silica content ≥95%, particle size 8 μm) in a 6% hydrochloric acid solution, stir and acid wash at 75℃ for 50 min, filter, wash until neutral, and dry to obtain activated diatomaceous earth; (2) Activated diatomaceous earth and the first silane coupling agent (KH590) were added to a mixer at a mass ratio of 8.5:1. The mixture was stirred at 50 rpm for 2.5 min at an initial temperature of 85°C. Then the temperature was raised to 135°C and held for 4.5 min. The mixture was then discharged to obtain primary modified diatomaceous earth. (3) Add the modified diatomaceous earth and titanate coupling agent (KR-38S) in a high-speed mixer at a mass ratio of 16:1 and mix at room temperature for 7 min to obtain modified diatomaceous earth.

[0030] The preparation method of the high dry and wet grip tire tread compound includes the following steps: (1) First stage of mixing: Solution-polymerized styrene-butadiene rubber and cis-butadiene rubber are added to a mixer and plasticized for 40 s. Then, silica, modified diatomaceous earth, multi-walled carbon nanotubes, functionalized resin, silane coupling agent (KH590), zinc oxide, stearic acid, antioxidant, TDAE environmentally friendly processing oil and dispersant are added. The mixture is mixed at 145°C for 4 min and discharged to obtain a first stage of compound. (2) Two-stage mixing: After cooling the first-stage compound to room temperature, put it back into the internal mixer and mix it at 120°C for 1.5 min. Then discharge it to obtain the second-stage compound. (3) Final mixing: After cooling the two-stage compound to room temperature, add it to the internal mixer, then add the accelerator and vulcanizing agent, mix at 100°C for 1.5 min, discharge the compound and sheet it to obtain the tire tread compound.

[0031] Comparative Example 1 The difference between this comparative example and Example 1 is that the modified diatomaceous earth is prepared using the following method: (1) Place diatomaceous earth (silica content ≥97%, particle size 10 μm) in an 8% hydrochloric acid solution, stir and acid wash at 70℃ for 45 min, filter, wash until neutral, and dry to obtain activated diatomaceous earth; (2) The first silane coupling agent (Si69) was added to an ethanol / water mixed solvent (volume ratio 4:1), the pH was adjusted to 4.5 with glacial acetic acid, and hydrolyzed at room temperature for 30 min to obtain the coupling agent hydrolysate; (3) The activated diatomaceous earth was added to the coupling agent hydrolysate and stirred at 70°C for 2 h. The mixture was then filtered, washed, and dried to obtain the modified diatomaceous earth. The mass ratio of the activated diatomaceous earth to the first silane coupling agent was 9:1.

[0032] Comparative Example 2 The difference between this comparative example and Example 1 is that the modified diatomaceous earth is prepared using the following method: (1) Place diatomaceous earth (silica content ≥97%, particle size 10 μm) in an 8% hydrochloric acid solution, stir and acid wash at 70℃ for 45 min, filter, wash until neutral, and dry to obtain activated diatomaceous earth; (2) Add activated diatomaceous earth and the first silane coupling agent (Si69) to a two-roll mill at a mass ratio of 9:1, and mix them repeatedly in a thin stream for 10 min at room temperature to mix the coupling agent with the diatomaceous earth and obtain primary modified diatomaceous earth. (3) Add the modified diatomaceous earth and titanate coupling agent (TTS) at a mass ratio of 18:1 into a high-speed mixer and mix at room temperature for 8 min to obtain modified diatomaceous earth.

[0033] Comparative Example 3 The difference between this comparative example and Example 1 is that the formulation, by weight, includes the following components: 100 parts solution-polymerized styrene-butadiene rubber, 3 parts modified diatomaceous earth, 60.7 parts silica, 0.3 parts multi-walled carbon nanotubes, 8 parts functionalized resin, 5 parts silane coupling agent (Si69), 4.5 parts zinc oxide, 2 parts stearic acid, 3 parts antioxidant, 2 parts accelerator, 1.8 parts vulcanizing agent (insoluble sulfur), 8 parts TDAE environmentally friendly operating oil, and 2 parts fatty acid ester dispersant.

[0034] The antioxidant is a mixture of antioxidant 4020 and antioxidant RD in a mass ratio of 2:1; the accelerator is a mixture of accelerator CZ and accelerator DPG in a mass ratio of 4:1; the functionalized resin is a mixture of terpene phenolic resin and C5 petroleum resin in a mass ratio of 1:1; and the silica is highly dispersible precipitated silica with a specific surface area of ​​150 m². 2 / g; the multi-walled carbon nanotubes have an outer diameter of 15 nm and a length of 10 μm.

[0035] Comparative Example 4 The difference between this comparative example and Example 1 is that the multi-walled carbon nanotubes in the formulation are replaced with graphene microsheets of equal mass.

[0036] Comparative Example 5 The difference between this comparative example and Example 1 is that the terpene phenolic resin of the functionalized resin in the formulation is replaced with an equal mass of coumarone-indene resin.

[0037] Performance testing After the rubber compounds of Examples 1-2 and Comparative Examples 1-5 were mixed according to their respective preparation methods, they were vulcanized at 150°C for 30 minutes to prepare standard samples for the following performance tests.

[0038] (1) Tensile properties: Tensile strength, elongation at break and stress at 100% and 300% of constant elongation were determined in accordance with GB / T 528-2009.

[0039] (2) Wear resistance: The DIN wear amount was determined according to GB / T 9867-2008, and the wear index was calculated (normalized with Example 1 as 100).

[0040] (3) Compression heat generation: The temperature rise of the rubber compound under dynamic compression conditions was determined with reference to GB / T 1687.3-2016.

[0041] (4) Dynamic mechanical properties: Referring to GB / T 9870.1-2006, the loss factor tanδ was determined using a dynamic thermomechanical analyzer. The test conditions were tensile mode, frequency 10 Hz, and heating rate 3℃ / min. The tanδ values ​​at 0℃ (characterizing wet grip), 25℃ (characterizing dry grip), and 60℃ (characterizing rolling resistance) were recorded.

[0042] The test results are shown in Table 1.

[0043] Table 1 Performance Test Results

[0044] Note: The DIN abrasion index is calculated based on Example 1 with a value of 100. The higher the value, the better the abrasion resistance.

[0045] As can be seen from the above performance test results, the rubber compounds of Examples 1 and 2 both exhibit excellent comprehensive performance, indicating that the technical solution of the present invention can effectively solve the problem of poor compatibility between diatomaceous earth and rubber matrix, while achieving a synergistic improvement in dry grip and wet grip, and the rolling resistance does not deteriorate significantly.

[0046] Comparative Example 1 used a solution method to modify diatomaceous earth. Due to the low efficiency of the hydrolysis reaction and the cumbersome process, the surface hydrophobicity of the modified diatomaceous earth was insufficient, resulting in uneven dispersion in the rubber and a significant decrease in both mechanical properties and grip. Comparative Example 2 used a room-temperature dry mixing method on an open mill instead of a high-temperature dynamic pre-modification method on a Banbury mixer in the preparation of modified diatomaceous earth. The room-temperature open mill mixing could not provide sufficient shear force and reaction temperature, resulting in insufficient chemical bonding between the first silane coupling agent and the silanol groups on the surface of the diatomaceous earth. This led to poor hydrophobic modification of the diatomaceous earth, and even subsequent secondary coating could not completely compensate for the insufficient interfacial bonding in the early stage. Therefore, the mechanical properties and grip of the rubber compound were lower than those of Example 1. Comparative Example 3 adjusted the dosage of the formulation components, resulting in a significant deterioration in the mechanical properties, abrasion resistance, and dry and wet grip of the rubber compound, and a significant increase in compression heat generation. Comparative Example 4 replaced multi-walled carbon nanotubes with graphene microsheets of equal mass. Because graphene is a two-dimensional sheet structure, it is prone to interlayer stacking, making it difficult to form a connected network and effectively exert a synergistic reinforcing effect. Therefore, its wear resistance and grip were inferior to those of Example 1. Comparative Example 5 replaced the terpene phenolic resin in the functionalized resin with coumarone-indene resin. The latter lacks polar groups such as phenolic hydroxyl groups, making it difficult to form a microphase separation structure with the rubber matrix. This weakened adhesion to wet surfaces, resulting in lower dry and wet grip compared to Example 1.

[0047] 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 tire tread compound with high dry and wet grip, characterized in that, By weight, it comprises the following components: 100 parts diene rubber, 5-15 parts modified diatomaceous earth, 40-70 parts silica, 0.5-3 parts multi-walled carbon nanotubes, 2-8 parts functionalized resin, 3-8 parts silane coupling agent, 3-6 parts zinc oxide, 1-3 parts stearic acid, 2-4 parts antioxidant, 1-3 parts accelerator, 1-2.5 parts vulcanizing agent, 5-12 parts processing oil, and 1-3 parts dispersant. The modified diatomaceous earth is prepared by the following method: (1) Place the diatomaceous earth in a hydrochloric acid solution, stir and wash, filter, wash and dry to obtain activated diatomaceous earth; (2) Add activated diatomaceous earth and the first silane coupling agent into a mixer and mix for 2-3 minutes at an initial temperature of 80-100℃. Then raise the temperature to 130-150℃ and keep it constant for 3-5 minutes. Discharge to obtain primary modified diatomaceous earth. (3) Mix the modified diatomaceous earth with the titanate coupling agent in a high-speed mixer for 5-10 min to obtain the modified diatomaceous earth.

2. The high dry and wet grip tire tread compound according to claim 1, characterized in that, The mass ratio of activated diatomaceous earth to the first silane coupling agent in step (2) is 10:1 to 8:1; the mass ratio of primary modified diatomaceous earth to titanate coupling agent in step (3) is 20:1 to 15:

1.

3. The high dry and wet grip tire tread compound according to claim 1, characterized in that, The diatomaceous earth has a silica content of ≥90% and a particle size of 1~20 μm.

4. The high dry and wet grip tire tread compound according to claim 1, characterized in that, The silica is a highly dispersible precipitated silica with a specific surface area of ​​120~180 m². 2 / g.

5. The high dry and wet grip tire tread compound according to claim 1, characterized in that, The functionalized resin is a mixture of terpene phenolic resin and C5 petroleum resin, with a mass ratio of 1:2 to 2:

1.

6. The high dry and wet grip tire tread compound according to claim 1, characterized in that, The first silane coupling agent and the silane coupling agent are each independently selected from at least one of Si69, Si75, KH590 or KH550; the titanate coupling agent is selected from at least one of TTS or KR-38S.

7. The high dry and wet grip tire tread compound according to claim 1, characterized in that, The diene-based rubber is at least one of solution-polymerized styrene-butadiene rubber, cis-butadiene rubber, and natural rubber.

8. The high dry and wet grip tire tread compound according to claim 1, characterized in that, The mass ratio of the modified diatomite, multi-walled carbon nanotubes and functionalized resin is (8~12):1:(3~6).

9. The method for preparing the high dry and wet grip tire tread compound according to any one of claims 1-8, characterized in that, Includes the following steps: (1) First stage of compounding: Add diene rubber to a mixer for plasticizing, then add silica, modified diatomaceous earth, multi-walled carbon nanotubes, functionalized resin, silane coupling agent, zinc oxide, stearic acid, antioxidant, processing oil and dispersant, mix, and discharge to obtain a first stage of compounded rubber. (2) Two-stage mixing: After cooling the first-stage compound to room temperature, it is put back into the internal mixer for mixing and then discharged to obtain the second-stage compound. (3) Final mixing: After cooling the two-stage compound to room temperature, add it to a two-roll mill or internal mixer, then add accelerator and vulcanizing agent, mix, discharge the rubber and sheet to obtain the tire tread rubber.

10. The preparation method according to claim 9, characterized in that, The mixing temperature in step (1) is 140~160℃ and the mixing time is 2~5 min; the mixing temperature in step (2) is 100~130℃ and the mixing time is 1~3 min; the mixing temperature in step (3) is 80~110℃ and the mixing time is 1~3 min.

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